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Sample records for ppc microfluidic chips

  1. Purification and preconcentration of genomic DNA from whole cell lysates using photoactivated polycarbonate (PPC) microfluidic chips.

    PubMed

    Witek, Malgorzata A; Llopis, Shawn D; Wheatley, Abigail; McCarley, Robin L; Soper, Steven A

    2006-06-06

    We discuss the use of a photoactivated polycarbonate (PPC) microfluidic chip for the solid-phase, reversible immobilization (SPRI) and purification of genomic DNA (gDNA) from whole cell lysates. The surface of polycarbonate was activated by UV radiation resulting in a photo-oxidation reaction, which produced a channel surface containing carboxylate groups. The gDNA was selectively captured on this photoactivated surface in an immobilization buffer, which consisted of 3% polyethylene glycol, 0.4 M NaCl and 70% ethanol. The methodology reported herein is similar to conventional SPRI in that surface-confined carboxylate groups are used for the selective immobilization of DNA; however, no magnetic beads or a magnetic field are required. As observed by UV spectroscopy, a load of approximately 7.6 +/- 1.6 microg/ml of gDNA was immobilized onto the PPC bed. The recovery of DNA following purification was estimated to be 85 +/- 5%. The immobilization and purification assay using this PPC microchip could be performed within approximately 25 min as follows: (i) DNA immobilization approximately 6 min, (ii) chip washout with ethanol 10 min, and (iii) drying and gDNA desorption approximately 6 min. The PPC microchip could also be used for subsequent assays with no substantial loss in recovery, no observable carryover and no need for 'reactivation' of the PC surface with UV light.

  2. Microfluidic Chips for Semen Analysis

    PubMed Central

    Segerink, L.I.; Sprenkels, A.J.; Oosterhuis, G.J.E.; Vermes, I.; van den Berg, A.

    2012-01-01

    The gold standard of semen analysis is still an manual method, which is time-consuming, labour intensive and needs thorough quality control. Microfluidics can also offer advantages for this application. Therefore a first step in the development of a microfluidic chip has been made, which enables the man the semen analysis at home. In this article recent efforts to determine the concentration and motility using a microfluidic chip are summarized. PMID:27683417

  3. Voltammetry on microfluidic chip platforms

    PubMed

    Wang; Polsky; Tian; Chatrathi

    2000-11-01

    Microfluidic chip devices are shown to be attractive platforms for performing microscale voltammetric analysis and for integrating voltammetric procedures with on-chip chemical reactions and fluid manipulations. Linear-sweep, square-wave, and adsorptive-stripping voltammograms are recorded while electrokinetically "pumping" the sample through the microchannels. The adaptation of voltammetric techniques to microfluidic chip operation requires an assessment of the effect of relevant experimental variables, particularly the high voltage used for driving the electroosmotic flow, upon the background current, potential window, and size or potential of the voltammetric signal. The exact potential window of the chip detector is dependent upon the driving voltage. Manipulation of the electroosmotic flow opens the door to hydrodynamic modulation (stopped-flow) and reversed-flow operations. The modulated analyte velocity permits compensation of the microchip voltammetric background. Reversal of the driving voltage polarity offers extended residence times in the detector compartment. Rapid square-wave voltammetry/flow injection operation allows a detection limit of 2 x 10(-12) mol (i.e., 2 pmol) of 2,4,6-trinitrotoluene (TNT) in connection with 47 nL of injected sample. The ability of integrating chemical reactions with voltammetric detection is demonstrated for adsorptive stripping measurements of trace nickel using the nickel-dimethylglyoxime model system. The voltammetric response is characterized using catechol, hydrazine, TNT, and nickel as test species. The ability to perform on-chip voltammertic protocols in advantageous over nanovial voltammetric operations that lack a liquid-handling capability. Coupling the versatility of microfluidic chips with the rich information content of voltammetry thus opens an array of future opportunities.

  4. Rapid prototyping of glass microfluidic chips

    NASA Astrophysics Data System (ADS)

    Kotz, Frederik; Plewa, Klaus; Bauer, Werner; Hanemann, Thomas; Waldbaur, Ansgar; Wilhelm, Elisabeth; Neumann, Christiane; Rapp, Bastian E.

    2015-03-01

    In academia the rapid and flexible creation of microfluidic chips is of great importance for microfluidic research. Besides polymers glass is a very important material especially when high chemical and temperature resistance are required. However, glass structuring is a very hazardous process which is not accessible to most members of the microfluidic community. We therefore sought a new method for the rapid and simple creation of transparent microfluidic glass chips by structuring and sintering amorphous silica suspensions. The whole process from a digital mask layout to a microstructured glass sheet can be done within two days. In this paper we show the applicability of this process to fabricate capillary driven microfluidic systems.

  5. Whole-Teflon microfluidic chips

    PubMed Central

    Ren, Kangning; Dai, Wen; Zhou, Jianhua; Su, Jing; Wu, Hongkai

    2011-01-01

    Although microfluidics has shown exciting potential, its broad applications are significantly limited by drawbacks of the materials used to make them. In this work, we present a convenient strategy for fabricating whole-Teflon microfluidic chips with integrated valves that show outstanding inertness to various chemicals and extreme resistance against all solvents. Compared with other microfluidic materials [e.g., poly(dimethylsiloxane) (PDMS)] the whole-Teflon chip has a few more advantages, such as no absorption of small molecules, little adsorption of biomolecules onto channel walls, and no leaching of residue molecules from the material bulk into the solution in the channel. Various biological cells have been cultured in the whole-Teflon channel. Adherent cells can attach to the channel bottom, spread, and proliferate well in the channels (with similar proliferation rate to the cells in PDMS channels with the same dimensions). The moderately good gas permeability of the Teflon materials makes it suitable to culture cells inside the microchannels for a long time. PMID:21536918

  6. Whole-Teflon microfluidic chips.

    PubMed

    Ren, Kangning; Dai, Wen; Zhou, Jianhua; Su, Jing; Wu, Hongkai

    2011-05-17

    Although microfluidics has shown exciting potential, its broad applications are significantly limited by drawbacks of the materials used to make them. In this work, we present a convenient strategy for fabricating whole-Teflon microfluidic chips with integrated valves that show outstanding inertness to various chemicals and extreme resistance against all solvents. Compared with other microfluidic materials [e.g., poly(dimethylsiloxane) (PDMS)] the whole-Teflon chip has a few more advantages, such as no absorption of small molecules, little adsorption of biomolecules onto channel walls, and no leaching of residue molecules from the material bulk into the solution in the channel. Various biological cells have been cultured in the whole-Teflon channel. Adherent cells can attach to the channel bottom, spread, and proliferate well in the channels (with similar proliferation rate to the cells in PDMS channels with the same dimensions). The moderately good gas permeability of the Teflon materials makes it suitable to culture cells inside the microchannels for a long time.

  7. Microfluidic on chip viscometers.

    PubMed

    Chevalier, J; Ayela, F

    2008-07-01

    We present the design and the process of fabrication of micromachined capillary on chip rheometers which have performed wall shear stress and shear rate measurements on silicon oil and ethanol-based nanofluids. The originality of these devices comes from the fact that local pressure drop measurements are performed inside the microchannels. Thus, the advantage over existing microviscometers is that they can be used with the fluid under test alone; no reference fluid nor posttreatment of the data are needed. Each on chip viscometer consists of anodically bonded silicon-Pyrex derivative microchannels equipped with local probes. The anodic bonding allows to reach relatively high pressure levels (up to approximately 10 bars) in the channels, and a broad range of shear stress and shear rate values is attainable. Dielectrophoretic and electrorheological effects can be highlighted by employing alternate microstripe electrodes patterned onto the inner side of the Pyrex wall.

  8. Materials for microfluidic chip fabrication.

    PubMed

    Ren, Kangning; Zhou, Jianhua; Wu, Hongkai

    2013-11-19

    Through manipulating fluids using microfabricated channel and chamber structures, microfluidics is a powerful tool to realize high sensitive, high speed, high throughput, and low cost analysis. In addition, the method can establish a well-controlled microenivroment for manipulating fluids and particles. It also has rapid growing implementations in both sophisticated chemical/biological analysis and low-cost point-of-care assays. Some unique phenomena emerge at the micrometer scale. For example, reactions are completed in a shorter amount of time as the travel distances of mass and heat are relatively small; the flows are usually laminar; and the capillary effect becomes dominant owing to large surface-to-volume ratios. In the meantime, the surface properties of the device material are greatly amplified, which can lead to either unique functions or problems that we would not encounter at the macroscale. Also, each material inherently corresponds with specific microfabrication strategies and certain native properties of the device. Therefore, the material for making the device plays a dominating role in microfluidic technologies. In this Account, we address the evolution of materials used for fabricating microfluidic chips, and discuss the application-oriented pros and cons of different materials. This Account generally follows the order of the materials introduced to microfluidics. Glass and silicon, the first generation microfluidic device materials, are perfect for capillary electrophoresis and solvent-involved applications but expensive for microfabriaction. Elastomers enable low-cost rapid prototyping and high density integration of valves on chip, allowing complicated and parallel fluid manipulation and in-channel cell culture. Plastics, as competitive alternatives to elastomers, are also rapid and inexpensive to microfabricate. Their broad variety provides flexible choices for different needs. For example, some thermosets support in-situ fabrication of

  9. Microfluidic organs-on-chips.

    PubMed

    Bhatia, Sangeeta N; Ingber, Donald E

    2014-08-01

    An organ-on-a-chip is a microfluidic cell culture device created with microchip manufacturing methods that contains continuously perfused chambers inhabited by living cells arranged to simulate tissue- and organ-level physiology. By recapitulating the multicellular architectures, tissue-tissue interfaces, physicochemical microenvironments and vascular perfusion of the body, these devices produce levels of tissue and organ functionality not possible with conventional 2D or 3D culture systems. They also enable high-resolution, real-time imaging and in vitro analysis of biochemical, genetic and metabolic activities of living cells in a functional tissue and organ context. This technology has great potential to advance the study of tissue development, organ physiology and disease etiology. In the context of drug discovery and development, it should be especially valuable for the study of molecular mechanisms of action, prioritization of lead candidates, toxicity testing and biomarker identification.

  10. Wax-bonding 3D microfluidic chips.

    PubMed

    Gong, Xiuqing; Yi, Xin; Xiao, Kang; Li, Shunbo; Kodzius, Rimantas; Qin, Jianhua; Wen, Weijia

    2010-10-07

    We report a simple, low-cost and detachable microfluidic chip incorporating easily accessible paper, glass slides or other polymer films as the chip materials along with adhesive wax as the recycling bonding material. We use a laser to cut through the paper or film to form patterns and then sandwich the paper and film between glass sheets or polymer membranes. The hot-melt adhesive wax can realize bridge bonding between various materials, for example, paper, polymethylmethacrylate (PMMA) film, glass sheets, or metal plate. The bonding process is reversible and the wax is reusable through a melting and cooling process. With this process, a three-dimensional (3D) microfluidic chip is achievable by vacuating and venting the chip in a hot-water bath. To study the biocompatibility and applicability of the wax-based microfluidic chip, we tested the PCR compatibility with the chip materials first. Then we applied the wax-paper based microfluidic chip to HeLa cell electroporation (EP). Subsequently, a prototype of a 5-layer 3D chip was fabricated by multilayer wax bonding. To check the sealing ability and the durability of the chip, green fluorescence protein (GFP) recombinant Escherichia coli (E. coli) bacteria were cultured, with which the chemotaxis of E. coli was studied in order to determine the influence of antibiotic ciprofloxacin concentration on the E. coli migration.

  11. A Microfluidic Chip for ICPMS Sample Introduction

    PubMed Central

    Verboket, Pascal E.; Borovinskaya, Olga; Meyer, Nicole; Günther, Detlef; Dittrich, Petra S.

    2015-01-01

    This protocol discusses the fabrication and usage of a disposable low cost microfluidic chip as sample introduction system for inductively coupled plasma mass spectrometry (ICPMS). The chip produces monodisperse aqueous sample droplets in perfluorohexane (PFH). Size and frequency of the aqueous droplets can be varied in the range of 40 to 60 µm and from 90 to 7,000 Hz, respectively. The droplets are ejected from the chip with a second flow of PFH and remain intact during the ejection. A custom-built desolvation system removes the PFH and transports the droplets into the ICPMS. Here, very stable signals with a narrow intensity distribution can be measured, showing the monodispersity of the droplets. We show that the introduction system can be used to quantitatively determine iron in single bovine red blood cells. In the future, the capabilities of the introduction device can easily be extended by the integration of additional microfluidic modules. PMID:25867751

  12. A microfluidic chip for ICPMS sample introduction.

    PubMed

    Verboket, Pascal E; Borovinskaya, Olga; Meyer, Nicole; Günther, Detlef; Dittrich, Petra S

    2015-03-05

    This protocol discusses the fabrication and usage of a disposable low cost microfluidic chip as sample introduction system for inductively coupled plasma mass spectrometry (ICPMS). The chip produces monodisperse aqueous sample droplets in perfluorohexane (PFH). Size and frequency of the aqueous droplets can be varied in the range of 40 to 60 µm and from 90 to 7,000 Hz, respectively. The droplets are ejected from the chip with a second flow of PFH and remain intact during the ejection. A custom-built desolvation system removes the PFH and transports the droplets into the ICPMS. Here, very stable signals with a narrow intensity distribution can be measured, showing the monodispersity of the droplets. We show that the introduction system can be used to quantitatively determine iron in single bovine red blood cells. In the future, the capabilities of the introduction device can easily be extended by the integration of additional microfluidic modules.

  13. The processing technology of PMMA micro-fluidic chip

    NASA Astrophysics Data System (ADS)

    Mu, Lili; Rong, Li; Guo, Shuheng; Liu, Qiong

    2016-01-01

    In order to enrich the production method of micro-fluidic chip and simplify its processing technology, the paper discussed the double-sided adhesive layer for channel layer, with PMMA (polymethyl methacrylate) for fabrication of microfluidic chip with the cover plate and the bottom plate. Taking 40 mm (long) x 20 mm (wide) x 2.2 mm (thick) liquid drop to separate the microfluidic chip as an example, details the design and machining process of the chip. Experiments show that surface quality is high and processing speed is fast when using this technology to process the chip. Thus, it can realize the mass production of micro fluidic chip.

  14. Microfluidics for miniaturized laboratories on a chip.

    PubMed

    Franke, Thomas A; Wixforth, Achim

    2008-10-24

    Microfluidic systems promise solutions for high throughput and highly specific analysis for biology, medicine and chemistry while consuming only tiny amounts of reactants and space. On these lab-on-a-chip platforms often multiple physical effects such as electrokinetic, acoustic or capillary phenomena from various disciplines are exploited to gain the optimal functionality. The fluidics on these small length scales differ significantly from our experience of the macroscopic world. In this Review we survey some of the approaches and techniques to handle minute amounts of fluid volumes in microfluidic systems with special focus on surface acoustic wave driven fluidics, a technique developed in our laboratory. Here, we outline the basics of this technique and demonstrate, for example, how acoustic mixing and fluid actuation is realized. Furthermore we discuss the interplay of different physical effects in microfluidic systems and illustrate their usefulness for several applications.

  15. Microfluidic distillation chip for methanol concentration detection.

    PubMed

    Wang, Yao-Nan; Liu, Chan-Chiung; Yang, Ruey-Jen; Ju, Wei-Jhong; Fu, Lung-Ming

    2016-03-17

    An integrated microfluidic distillation system is proposed for separating a mixed ethanol-methanol-water solution into its constituent components. The microfluidic chip is fabricated using a CO2 laser system and comprises a serpentine channel, a boiling zone, a heating zone, and a cooled collection chamber filled with de-ionized (DI) water. In the proposed device, the ethanol-methanol-water solution is injected into the microfluidic chip and driven through the serpentine channel and into the collection chamber by means of a nitrogen carrier gas. Following the distillation process, the ethanol-methanol vapor flows into the collection chamber and condenses into the DI water. The resulting solution is removed from the collection tank and reacted with a mixed indicator. Finally, the methanol concentration is inversely derived from the absorbance measurements obtained using a spectrophotometer. The experimental results show the proposed microfluidic system achieves an average methanol distillation efficiency of 97%. The practicality of the proposed device is demonstrated by detecting the methanol concentrations of two commercial fruit wines. It is shown that the measured concentration values deviate by no more than 3% from those obtained using a conventional bench top system.

  16. Reagent-loaded plastic microfluidic chips for detecting homocysteine

    NASA Astrophysics Data System (ADS)

    Suk, Ji Won; Jang, Jae-Young; Cho, Jun-Hyeong

    2008-05-01

    This report describes the preliminary study on plastic microfluidic chips with pre-loaded reagents for detecting homocysteine (Hcy). All reagents needed in an Hcy immunoassay were included in a microfluidic chip to remove tedious assay steps. A simple and cost-effective bonding method was developed to realize reagent-loaded microfluidic chips. This technique uses an intermediate layer between two plastic substrates by selectively patterning polydimethylsiloxane (PDMS) on the embossed surface of microchannels and fixing the substrates under pressure. Using this bonding method, the competitive immunoassay for SAH, a converted form of Hcy, was performed without any damage to reagents in chips, and the results showed that the fluorescent signal from antibody antigen binding decreased as the SAH concentration increased. Based on the SAH immunoassay, whole immunoassay steps for Hcy detection were carried out in plastic microfluidic chips with all necessary reagents. These experiments demonstrated the feasibility of the Hcy immunoassay in microfluidic devices.

  17. Hybrid IC / Microfluidic Chips for the Manipulation of Biological Cells

    NASA Astrophysics Data System (ADS)

    Lee, Hakho

    2005-03-01

    A hybrid IC / Microfluidic chip that can manipulate individual biological cells in a fluid with microscopic resolution has been demonstrated. The chip starts with a custom-designed silicon integrated circuit (IC) produced in a foundry using standard processing techniques. A microfluidic chamber is then fabricated on top of the IC to provide a biocompatible environment. The motion of biological cells in the chamber is controlled using a two-dimensional array of micro-scale electromagnets in the IC that generate spatially patterned magnetic fields. A local peak in the magnetic field amplitude will trap a magnetic bead and an attached cell; by moving the peak's location, the bead-bound cell can be moved to any position on the chip surface above the array. By generating multiple peaks, many cells can be moved independently along separate paths, allowing many different manipulations of individual cells. The hybrid IC / Microfluidic chip can be used, for example, to sort cells or to assemble tissue on micrometer length scales. To prove the concept, an IC / Microfluidic chip was fabricated, based on a custom-designed IC that contained a two-dimensional microcoil array with integrated current sources and control circuits. The chip was tested by trapping and moving biological cells tagged with magnetic beads inside the microfluidic chamber over the array. By combining the power of silicon technology with the biocompatibility of microfluidics, IC / Microfluidic chips will make new types of investigations possible in biological and biomedical studies.

  18. Microfluidic chips for protein differential expression profiling.

    PubMed

    Armenta, Jenny M; Dawoud, Abdulilah A; Lazar, Iulia M

    2009-04-01

    Biomarker discovery and screening using novel proteomic technologies is an area that is attracting increased attention in the biomedical community. Early detection of abnormal physiological conditions will be highly beneficial for diagnosing various diseases and increasing survivability rates. Clearly, progress in this area will depend on the development of fast, reliable, and highly sensitive and specific sample bioanalysis methods. Microfluidics has emerged as a technology that could become essential in proteomics research as it enables the integration of all sample preparation, separation, and detection steps, with the added benefit of enhanced sample throughput. The combination of these advantages with the sensitivity and capability of MS detection to deliver precise structural information makes microfluidics-MS a very competitive technology for biomarker discovery. The integration of LC microchip devices with MS detection, and specifically their applicability to biomarker screening applications in MCF-7 breast cancer cellular extracts is reported in this manuscript. Loading approximately 0.1-1 microg of crude protein extract tryptic digest on the chip has typically resulted in the reliable identification of approximately 40-100 proteins. The potential of an LC-ESI-MS chip for comparative proteomic analysis of isotopically labeled MCF-7 breast cancer cell extracts is explored for the first time.

  19. Research of bubble flow characteristics in microfluidic chip

    NASA Astrophysics Data System (ADS)

    Qiu, Chao; Cheng, Han; Chen, Shuxian

    2017-04-01

    Bubble is the heart of the microfluidic chip, which takes a significant role in drug release, biological detection and so on. In this case, bubble flow characteristics in microfluidic chip are the key to realize its function. In this paper, bubble flow characteristics in the microfluidic chip have been studied with high speed photography system by controlling the wettability and the heat flux of the microelectrode surface. The result shows that bubble flows faster on the electrode with hydrophobic surface. In addition, loading current to the electrode with hydrophilic surface could also speed up the movement of bubble, and the flow rate of bubble increases with the increasing heat flux of the electrode.

  20. Disposable world-to-chip interface for digital microfluidics

    DOEpatents

    Van Dam, R. Michael; Shah, Gaurav; Keng, Pei-Yuin

    2017-05-16

    The present disclosure sets forth incorporating microfluidic chips interfaces for use with digital microfluidic processes. Methods and devices according to the present disclosure utilize compact, integrated platforms that interface with a chip upstream and downstream of the reaction, as well as between intermediate reaction steps if needed. In some embodiments these interfaces are automated, including automation of a multiple reagent process. Various reagent delivery systems and methods are also disclosed.

  1. Droplet Microfluidics for Chip-Based Diagnostics

    PubMed Central

    Kaler, Karan V. I. S.; Prakash, Ravi

    2014-01-01

    Droplet microfluidics (DMF) is a fluidic handling technology that enables precision control over dispensing and subsequent manipulation of droplets in the volume range of microliters to picoliters, on a micro-fabricated device. There are several different droplet actuation methods, all of which can generate external stimuli, to either actively or passively control the shape and positioning of fluidic droplets over patterned substrates. In this review article, we focus on the operation and utility of electro-actuation-based DMF devices, which utilize one or more micro-/nano-patterned substrates to facilitate electric field-based handling of chemical and/or biological samples. The underlying theory of DMF actuations, device fabrication methods and integration of optical and opto-electronic detectors is discussed in this review. Example applications of such electro-actuation-based DMF devices have also been included, illustrating the various actuation methods and their utility in conducting chip-based laboratory and clinical diagnostic assays. PMID:25490590

  2. Packaging of microfluidic chips via interstitial bonding technique.

    PubMed

    Lu, Chunmeng; Lee, L James; Juang, Yi-Je

    2008-04-01

    In this paper, we describe an interstitial bonding technique for packaging of microfluidic chips. The cover plate is first placed on top of the microfluidic chip, followed by dispensing the UV-curable resin into the resin-loading reservoirs. With the interstitial space between the cover plate and the microfluidic chip connecting to the loading reservoirs, the UV-curable resin wicks through capillary force action and hydrostatic pressure generated by the liquid level in the resin-loading reservoirs. When reaching the microchannels, the UV-curable resin stops flowing into the microchannels due to the force balance between the surface tension and hydrostatic pressure. The assembly is then placed under the UV light, followed by further curing in the thermal oven. It is found that there is no leakage from the bonded microfluidic chips and a good DNA separation result was obtained by using the microfluidic chips as fabricated. This bonding technique is relatively simple and fast, which can be applied to the packaging of microfluidic chips made from hybrid materials with complicated designs as long as the interstitial space connects to the loading reservoirs.

  3. Integrated polymerase chain reaction chips utilizing digital microfluidics.

    PubMed

    Chang, Yi-Hsien; Lee, Gwo-Bin; Huang, Fu-Chun; Chen, Yi-Yu; Lin, Jr-Lung

    2006-09-01

    This study reports an integrated microfluidic chip for polymerase chain reaction (PCR) applications utilizing digital microfluidic chip (DMC) technology. Several crucial procedures including sample transportation, mixing, and DNA amplification were performed on the integrated chip using electro-wetting-on-dielectric (EWOD) effect. An innovative concept of hydrophobic/hydrophilic structure has been successfully demonstrated to integrate the DMC chip with the on-chip PCR device. Sample droplets were generated, transported and mixed by the EWOD-actuation. Then the mixture droplets were transported to a PCR chamber by utilizing the hydrophilic/hydrophobic interface to generate required surface tension gradient. A micro temperature sensor and two micro heaters inside the PCR chamber along with a controller were used to form a micro temperature control module, which could perform precise PCR thermal cycling for DNA amplification. In order to demonstrate the performance of the integrated DMC/PCR chips, a detection gene for Dengue II virus was successfully amplified and detected. The new integrated DMC/PCR chips only required an operation voltage of 12V(RMS) at a frequency of 3 KHz for digital microfluidic actuation and 9V(DC) for thermal cycling. When compared to its large-scale counterparts for DNA amplification, the developed system consumed less sample and reagent and could reduce the detection time. The developed chips successfully demonstrated the feasibility of Lab-On-a-Chip (LOC) by utilizing EWOD-based digital microfluidics.

  4. Microfluidic chip for high efficiency DNA extraction.

    PubMed

    Chung, Yung-Chiang; Jan, Ming-Shiung; Lin, Yu-Cheng; Lin, Ju-Hwa; Cheng, Wang-Chin; Fan, Chia-Yu

    2004-04-01

    A high efficiency DNA extraction microchip was designed to extract DNA from lysed cells using immobilized beads and the solution flowing back and forth. This chip was able to increase the extraction efficiency by 2-fold when there was no serum. When serum existed in the solution, the extraction efficiency of immobilized beads was 88-fold higher than that of free beads. The extraction efficiency of the microchip was tested under different conditions and numbers of E. coli cells. When the number of E. coli cells was between 10(6) and 10(8) in 25 microl of whole blood, the extraction efficiency using immobilized beads was only slightly higher than that using free beads (10(0) to 10(1) fold). When the number of E. coli cells was in the range 10(4) to 10(6) in 25 microl of whole blood, the extraction efficiency of immobilized beads was greater than that of the free beads (10(1) to 10(2) fold). When the number of E. coli cells was lower, in the range 10(3) to 10(4) in 25 microl of whole blood, the extraction efficiency of immobilized beads was much higher than that of the free beads (10(2) to 10(3) fold). This study indicated that DNA could be efficiently extracted even when the number of bacterial cells was smaller (10(5) to 10(3)). This microfluidic extraction chip could find potential applications in rare sample genomic study.

  5. USB-driven microfluidic chips on printed circuit boards.

    PubMed

    Li, Jiang; Wang, Yixuan; Dong, Enkai; Chen, Haosheng

    2014-03-07

    A technology is presented to fabricate a microfluidic chip in which the microchannels and the microelectrodes of sensors are integrated directly into the copper sheet on a printed circuit board. Then, we demonstrate an application of the generation of oil-in-water and water-in-oil emulsion droplets on this microfluidic chip driven by a USB interface, and the droplet size is detected by the microelectrodes on the downstream microchannel. The integration of the microfluidic chip is improved by the direct connection of the channels to the microelectrodes of the driving unit and of the sensors on the same substrate, and it is a promising way to integrate microfluidics into a more complex micro electrical-mechanical system (MEMS).

  6. DNA-enrichment microfluidic chip for chromatin immunoprecipitation.

    PubMed

    Oh, Hyun Jik; Park, Joong Yull; Park, Sung Eun; Lee, Bo Yun; Park, Jong Sung; Kim, Suel-Kee; Yoon, Tae Joong; Lee, Sang-Hoon

    2009-04-15

    Chromatin immunoprecipitation (ChIP) is a powerful and widely applied technique for detecting association of individual proteins with specific genomic regions; the technique requires several complex steps and is tedious. In this paper, we develop a microbead-packed microfluidic chip which eliminates most of the laborious, time-consuming, and skill-dependent processes of the ChIP procedure. A computational fluid dynamics model was established to analyze fluidic behavior in a microbead-packed microchannel. With the use of the new chip, a ChIP procedure was performed to purify the GAPDH (glyceraldehyde 3-phosphate dehydrogenase) gene from human embryonic kidney cells (cell line 293). The ChIP capability of the microfluidic chip was evaluated and compared with that of a commercial assay kit; the precipitation performance of both methods was almost identical as shown by quantitative measurement of DNA. However, our chip offers the advantage of low resin volume, and the experimental time is greatly reduced. In addition, our method is less dependent on individual technical skill. Therefore, we expect that our microfluidic chip-based ChIP method will be widely used in DNA-, gene-, and protein-related research and will improve experimental efficiency.

  7. Directed evolution of enzymes using microfluidic chips

    NASA Astrophysics Data System (ADS)

    Pilát, Zdeněk.; Ježek, Jan; Šmatlo, Filip; Kaůka, Jan; Zemánek, Pavel

    2016-12-01

    Enzymes are highly versatile and ubiquitous biological catalysts. They can greatly accelerate large variety of reactions, while ensuring appropriate catalytic activity and high selectivity. These properties make enzymes attractive biocatalysts for a wide range of industrial and biomedical applications. Over the last two decades, directed evolution of enzymes has transformed the field of protein engineering. We have devised microfluidic systems for directed evolution of haloalkane dehalogenases in emulsion droplets. In such a device, individual bacterial cells producing mutated variants of the same enzyme are encapsulated in microdroplets and supplied with a substrate. The conversion of a substrate by the enzyme produced by a single bacterium changes the pH in the droplet which is signalized by pH dependent fluorescence probe. The droplets with the highest enzymatic activity can be separated directly on the chip by dielectrophoresis and the resultant cell lineage can be used for enzyme production or for further rounds of directed evolution. This platform is applicable for fast screening of large libraries in directed evolution experiments requiring mutagenesis at multiple sites of a protein structure.

  8. Microfluidic cell chips for high-throughput drug screening.

    PubMed

    Chi, Chun-Wei; Ahmed, Ah Rezwanuddin; Dereli-Korkut, Zeynep; Wang, Sihong

    2016-05-01

    The current state of screening methods for drug discovery is still riddled with several inefficiencies. Although some widely used high-throughput screening platforms may enhance the drug screening process, their cost and oversimplification of cell-drug interactions pose a translational difficulty. Microfluidic cell-chips resolve many issues found in conventional HTS technology, providing benefits such as reduced sample quantity and integration of 3D cell culture physically more representative of the physiological/pathological microenvironment. In this review, we introduce the advantages of microfluidic devices in drug screening, and outline the critical factors which influence device design, highlighting recent innovations and advances in the field including a summary of commercialization efforts on microfluidic cell chips. Future perspectives of microfluidic cell devices are also provided based on considerations of present technological limitations and translational barriers.

  9. Various On-Chip Sensors with Microfluidics for Biological Applications

    PubMed Central

    Lee, Hun; Xu, Linfeng; Koh, Domin; Nyayapathi, Nikhila; Oh, Kwang W.

    2014-01-01

    In this paper, we review recent advances in on-chip sensors integrated with microfluidics for biological applications. Since the 1990s, much research has concentrated on developing a sensing system using optical phenomena such as surface plasmon resonance (SPR) and surface-enhanced Raman scattering (SERS) to improve the sensitivity of the device. The sensing performance can be significantly enhanced with the use of microfluidic chips to provide effective liquid manipulation and greater flexibility. We describe an optical image sensor with a simpler platform for better performance over a larger field of view (FOV) and greater depth of field (DOF). As a new trend, we review consumer electronics such as smart phones, tablets, Google glasses, etc. which are being incorporated in point-of-care (POC) testing systems. In addition, we discuss in detail the current optical sensing system integrated with a microfluidic chip. PMID:25222033

  10. Integrated microfluidic linking chip for scanning probe nanolithography

    NASA Astrophysics Data System (ADS)

    Ryu, Kee Suk; Wang, Xuefeng; Shaikh, Kashan; Bullen, David; Goluch, Edgar; Zou, Jun; Liu, Chang; Mirkin, Chad A.

    2004-07-01

    This letter reports an architecture for a microfluidic chip that dresses (inks) multiple nanolithography tips in a high-density array in a parallel and multiplexed fashion. The microfluidic chip consists of multiple precision patterned thin-film poly(dimethylsiloxane) (PDMS) patches serving as porous inking pads. Inking chemicals are supplied from loading reservoirs to the inking pads through microfluidic channels. The gas-permeable thin PDMS membranes allow ink molecules to diffuse through while preventing bulk liquid from overflowing or evaporating. The inking chip provides high-density inking, easy loading of inks, and reduced evaporation losses. We present the fabrication process and inking of scanning probe contact printing probes and commercial nitride probes.

  11. On-chip cell analysis platform: Implementation of contact fluorescence microscopy in microfluidic chips

    NASA Astrophysics Data System (ADS)

    Takehara, Hiroaki; Kazutaka, Osawa; Haruta, Makito; Noda, Toshihiko; Sasagawa, Kiyotaka; Tokuda, Takashi; Ohta, Jun

    2017-09-01

    Although fluorescence microscopy is the gold standard tool for biomedical research and clinical applications, their use beyond well-established laboratory infrastructures remains limited. The present study investigated a novel on-chip cell analysis platform based on contact fluorescence microscopy and microfluidics. Combined use of a contact fluorescence imager based on complementary metal-oxide semiconductor technology and an ultra-thin glass bottom microfluidic chip enabled both to observe living cells with minimal image distortion and to ease controlling and handling of biological samples (e.g. cells and biological molecules) in the imaged area. A proof-of-concept experiment of on-chip detection of cellular response to endothelial growth factor demonstrated promising use for the recently developed on-chip cell analysis platform. Contact fluorescence microscopy has numerous desirable features including compatibility with plastic microfluidic chips and compatibility with the electrical control system, and thus will fulfill the requirements of a fully automated cell analysis system.

  12. On-chip Microfluidic Multimodal Swimmer toward 3D Navigation

    PubMed Central

    Barbot, Antoine; Decanini, Dominique; Hwang, Gilgueng

    2016-01-01

    Mobile microrobots have a promising future in various applications. These include targeted drug delivery, local measurement, biopsy or microassembly. Studying mobile microrobots inside microfluidics is an essential step towards such applications. But in this environment that was not designed for the robot, integration process and propulsion robustness still pose technological challenges. In this paper, we present a helical microrobot with three different motions, designed to achieve these goals. These motions are rolling, spintop motion and swimming. Through these multiple motions, microrobots are able to selectively integrate a chip through a microfluidic channel. This enables them to perform propulsion characterizations, 3D (Three Dimensional) maneuverability, particle cargo transport manipulation and exit from the chip. The microrobot selective integration inside microfluidics could lead to various in-vitro biologic or in-vivo biomedical applications. PMID:26791433

  13. On-chip Microfluidic Multimodal Swimmer toward 3D Navigation

    NASA Astrophysics Data System (ADS)

    Barbot, Antoine; Decanini, Dominique; Hwang, Gilgueng

    2016-01-01

    Mobile microrobots have a promising future in various applications. These include targeted drug delivery, local measurement, biopsy or microassembly. Studying mobile microrobots inside microfluidics is an essential step towards such applications. But in this environment that was not designed for the robot, integration process and propulsion robustness still pose technological challenges. In this paper, we present a helical microrobot with three different motions, designed to achieve these goals. These motions are rolling, spintop motion and swimming. Through these multiple motions, microrobots are able to selectively integrate a chip through a microfluidic channel. This enables them to perform propulsion characterizations, 3D (Three Dimensional) maneuverability, particle cargo transport manipulation and exit from the chip. The microrobot selective integration inside microfluidics could lead to various in-vitro biologic or in-vivo biomedical applications.

  14. [Application of microfluidic-chip in biomedicine].

    PubMed

    Bi, Ying-Nan; Zhang, Hui-Jing

    2006-01-01

    As a novel analytical technology, the research of Micro total analysis systems (micro-TAS) has been spreading rapidly. micro-TAS has been widely used to perform chemical and biochemical analysis. Microfluidic-based analytical system as micro-TAS's manily direction develops very fast in terms of it's reaction speed, reagent consumption, miniaturization, cost, and automation. After having proven the value of microfluidics for genetic, proteomic and cytomics analysis, this article also anticipates the development tendency of this technology in the biology medicine domain. It has demonstrated that a truly, easy-to-handle Microfluidic-based analytical device will be emerged in the future.

  15. A microfluidic microprocessor: controlling biomimetic containers and cells using hybrid integrated circuit/microfluidic chips.

    PubMed

    Issadore, David; Franke, Thomas; Brown, Keith A; Westervelt, Robert M

    2010-11-07

    We present an integrated platform for performing biological and chemical experiments on a chip based on standard CMOS technology. We have developed a hybrid integrated circuit (IC)/microfluidic chip that can simultaneously control thousands of living cells and pL volumes of fluid, enabling a wide variety of chemical and biological tasks. Taking inspiration from cellular biology, phospholipid bilayer vesicles are used as robust picolitre containers for reagents on the chip. The hybrid chip can be programmed to trap, move, and porate individual living cells and vesicles and fuse and deform vesicles using electric fields. The IC spatially patterns electric fields in a microfluidic chamber using 128 × 256 (32,768) 11 × 11 μm(2) metal pixels, each of which can be individually driven with a radio frequency (RF) voltage. The chip's basic functions can be combined in series to perform complex biological and chemical tasks and can be performed in parallel on the chip's many pixels for high-throughput operations. The hybrid chip operates in two distinct modes, defined by the frequency of the RF voltage applied to the pixels: Voltages at MHz frequencies are used to trap, move, and deform objects using dielectrophoresis and voltages at frequencies below 1 kHz are used for electroporation and electrofusion. This work represents an important step towards miniaturizing the complex chemical and biological experiments used for diagnostics and research onto automated and inexpensive chips.

  16. Polymer microfluidic chip for online monitoring of microarray hybridizations.

    PubMed

    Noerholm, Mikkel; Bruus, Henrik; Jakobsen, Mogens H; Telleman, Pieter; Ramsing, Niels B

    2004-02-01

    A disposable single use polymer microfluidics chip has been developed and manufactured by micro injection molding. The chip has the same outer dimensions as a standard microscope slide (25 x 76 x 1.1 mm) and is designed to be compatible with existing microscope slide handling equipment like microarray scanners. The chip contains an inlet, a 10 microL hybridization chamber capable of holding a 1000 spot array, a waste chamber and a vent to allow air to escape when sample is injected. The hybridization chamber ensures highly homogeneous hybridization conditions across the microarray. We describe the use of this chip in a flexible setup with fluorescence based detection, temperature control and liquid handling by computer controlled syringe pumps. The chip and the setup presented in this article provide a powerful tool for highly parallel studies of kinetics and thermodynamics of duplex formation in DNA microarrays. The experimental setup presented in this article enables the on-chip microarray to be hybridized and monitored at several different stringency conditions during a single assay. The performance of the chip and the setup is demonstrated by on-line measurements of a hybridization of a DNA target solution to a microarray. A presented numerical model indicates that the hybridization process in microfluidic hybridization assays is diffusion limited, due to the low values of the diffusion coefficients D of the DNA and RNA molecules involved.

  17. Fluorescence calibration research of microspheres in a microfluidic chip

    NASA Astrophysics Data System (ADS)

    Wang, Lin; Lian, Kun; Goettert, Jost

    2005-01-01

    Fluorescence calibration is usually done by preparing bio-samples with a series of concentrations and measuring their corresponding fluorescence intensities. A simplified approach is studied by using a microfluidic chip and microspheres. The fluorescence calibration can be carried out on the chip with only one concentration of the microspheres. Microspheres with the diameter of 1~5μm are very useful in bio-detection research. These microspheres are manufactured using high-quality, ultraclean polystyrene microspheres and loaded with a variety of proprietary dyes. They can be labeled with biotin-, NeutrAvdin-, streptavidin- and protein, which can be used as tracers for bio-detections. A microfluidic chip was successfully fabricated for the experiment, and preliminary experimental results have proved the feasibility of the approach for fluorescence calibration.

  18. Detection and classification of ebola on microfluidic chips

    NASA Astrophysics Data System (ADS)

    Lin, Xue; Jin, Xiangyu; Fan, Yunqian; Huang, Qin; Kou, Yue; Zu, Guo; Huang, Shiguang; Liu, Xiaosheng; Huang, Guoliang

    2016-10-01

    Point-of-care testing (POCT) for an infectious diseases is the prerequisite to control of the disease and limitation of its spread. A microfluidic chip for detection and classification of four strains of Ebola virus was developed and evaluated. This assay was based on reverse transcription loop-mediated isothermal amplification (RT-LAMP) and specific primers for Ebola Zaire virus, Ebola Sudan virus, Ebola Tai Forest virus and Ebola Bundibugyo virus were designed. The sensitivity of the microfluidic chip was under 103 copies per milliliter, as determined by ten repeated tests. This assay is unique in its ability to enable diagnosis of the Ebola infections and simultaneous typing of Ebola virus on a single chip. It offers short reaction time, ease of use and high specificity. These features should enable POCT in remote area during outbreaks of Ebola virus.

  19. The Role of Microfluidics for Organ on Chip Simulations

    PubMed Central

    Aziz, Aziz Ur Rehman; Geng, Chunyang; Fu, Mengjie; Yu, Xiaohui; Qin, Kairong; Liu, Bo

    2017-01-01

    A multichannel three-dimensional chip of a microfluidic cell culture which enables the simulation of organs is called an “organ on a chip” (OC). With the integration of many other technologies, OCs have been mimicking organs, substituting animal models, and diminishing the time and cost of experiments which is better than the preceding conventional in vitro models, which make them imperative tools for finding functional properties, pathological states, and developmental studies of organs. In this review, recent progress regarding microfluidic devices and their applications in cell cultures is discussed to explain the advantages and limitations of these systems. Microfluidics is not a solution but only an approach to create a controlled environment, however, other supporting technologies are needed, depending upon what is intended to be achieved. Microfluidic platforms can be integrated with additional technologies to enhance the organ on chip simulations. Besides, new directions and areas are mentioned for interested researchers in this field, and future challenges regarding the simulation of OCs are also discussed, which will make microfluidics more accurate and beneficial for biological applications. PMID:28952518

  20. A microfluidic chip for highly efficient cell capturing and pairing.

    PubMed

    Cui, Shaoyan; Liu, Yaoping; Wang, Wei; Sun, Yan; Fan, Yubo

    2011-09-01

    This paper examined the feasibility of a microfluidics chip for cell capturing and pairing with a high efficiency. The chip was fabricated by the polydimethylsiloxane-based soft-lithography technique and contained two suction duct arrays set in parallel on both sides of a main microchannel. Cells were captured and paired by activating two sets of suction ducts one by one with the help of syringe pumps along with switching the cell suspensions inside the main microchannel correspondingly. The effects of suction flow rate and the dimensions of suction channels on the cell capturing and pairing efficiency were characterized. The present chip was capable of creating 1024 pairs of two different cell populations in parallel. The preliminary experimental results showed that the cell capturing efficiency was 100% and the pairing one was 88% with an optimal suction rate of 5 μl/min in the chip in the 2 μm-sized suction duct chip. The cell viability after capture inside the microfluidic device was 90.0 ± 5.3%. With this cell capturing and pairing chip, interaction between cells in a single pair mode can be studied. The ability to create cell pairs has a number of biological applications for cell fusion, cell-cell interaction studies, and cell toxicity screening.

  1. The microfluidic puzzle: chip-oriented rapid prototyping.

    PubMed

    Lim, Jiseok; Maes, Florine; Taly, Valérie; Baret, Jean-Christophe

    2014-05-21

    We demonstrate a new concept for reconfigurable microfluidic devices from elementary functional units. Our approach suppresses the need for patterning, soft molding and bonding when details on a chip have to be modified. Our system has two parts, a base-platform used as a scaffold and functional modules which are combined by 'plug-and-play'. To demonstrate that our system sustains typical pressures in microfluidic experiments, we produce droplets of different sizes using T-junction modules with three different designs assembled successively on a 3 × 3 modular scaffold.

  2. Seamless integration of CMOS and microfluidics using flip chip bonding

    NASA Astrophysics Data System (ADS)

    Welch, David; Blain Christen, Jennifer

    2013-03-01

    We demonstrate the microassembly of PDMS (polydimethylsiloxane) microfluidics with integrated circuits made in complementary metal-oxide-semiconductor (CMOS) processes. CMOS-sized chips are flip chip bonded to a flexible polyimide printed circuit board (PCB) with commercially available solder paste patterned using a SU-8 epoxy. The average resistance of each flip chip bond is negligible and all connections are electrically isolated. PDMS is attached to the flexible polyimide PCB using a combination of oxygen plasma treatment and chemical bonding with 3-aminopropyltriethoxysilane. The total device has a burst pressure of 175 kPA which is limited by the strength of the flip chip attachment. This technique allows the sensor area of the die to act as the bottom of the microfluidic channel. The SU-8 provides a barrier between the pad ring (electrical interface) and the fluids; post-processing is not required on the CMOS die. This assembly method shows great promise for developing analytic systems which combine the strengths of microelectronics and microfluidics into one device.

  3. The promise of macromolecular crystallization in microfluidic chips

    NASA Technical Reports Server (NTRS)

    van der Woerd, Mark; Ferree, Darren; Pusey, Marc

    2003-01-01

    Microfluidics, or lab-on-a-chip technology, is proving to be a powerful, rapid, and efficient approach to a wide variety of bioanalytical and microscale biopreparative needs. The low materials consumption, combined with the potential for packing a large number of experiments in a few cubic centimeters, makes it an attractive technique for both initial screening and subsequent optimization of macromolecular crystallization conditions. Screening operations, which require a macromolecule solution with a standard set of premixed solutions, are relatively straightforward and have been successfully demonstrated in a microfluidics platform. Optimization methods, in which crystallization solutions are independently formulated from a range of stock solutions, are considerably more complex and have yet to be demonstrated. To be competitive with either approach, a microfluidics system must offer ease of operation, be able to maintain a sealed environment over several weeks to months, and give ready access for the observation and harvesting of crystals as they are grown.

  4. The promise of macromolecular crystallization in microfluidic chips

    NASA Technical Reports Server (NTRS)

    van der Woerd, Mark; Ferree, Darren; Pusey, Marc

    2003-01-01

    Microfluidics, or lab-on-a-chip technology, is proving to be a powerful, rapid, and efficient approach to a wide variety of bioanalytical and microscale biopreparative needs. The low materials consumption, combined with the potential for packing a large number of experiments in a few cubic centimeters, makes it an attractive technique for both initial screening and subsequent optimization of macromolecular crystallization conditions. Screening operations, which require a macromolecule solution with a standard set of premixed solutions, are relatively straightforward and have been successfully demonstrated in a microfluidics platform. Optimization methods, in which crystallization solutions are independently formulated from a range of stock solutions, are considerably more complex and have yet to be demonstrated. To be competitive with either approach, a microfluidics system must offer ease of operation, be able to maintain a sealed environment over several weeks to months, and give ready access for the observation and harvesting of crystals as they are grown.

  5. High Voltage Dielectrophoretic and Magnetophoretic Hybrid Integrated Circuit / Microfluidic Chip.

    PubMed

    Issadore, David; Franke, Thomas; Brown, Keith A; Hunt, Thomas P; Westervelt, Robert M

    2009-12-01

    A hybrid integrated circuit (IC) / microfluidic chip is presented that independently and simultaneously traps and moves microscopic objects suspended in fluid using both electric and magnetic fields. This hybrid chip controls the location of dielectric objects, such as living cells and drops of fluid, on a 60 × 61 array of pixels that are 30 × 38 μm(2) in size, each of which can be individually addressed with a 50 V peak-to-peak, DC to 10 MHz radio frequency voltage. These high voltage pixels produce electric fields above the chip's surface with a magnitude , resulting in strong dielectrophoresis (DEP) forces . Underneath the array of DEP pixels there is a magnetic matrix that consists of two perpendicular sets of 60 metal wires running across the chip. Each wire can be sourced with 120 mA to trap and move magnetically susceptible objects using magnetophoresis (MP). The DEP pixel array and magnetic matrix can be used simultaneously to apply forces to microscopic objects, such as living cells or lipid vesicles, that are tagged with magnetic nanoparticles. The capabilities of the hybrid IC / microfluidic chip demonstrated in this paper provide important building blocks for a platform for biological and chemical applications.

  6. On-chip photonic tweezers for photonics, microfluidics, and biology

    NASA Astrophysics Data System (ADS)

    Pin, Christophe; Renaut, Claude; Tardif, Manon; Jager, Jean-Baptiste; Delamadeleine, Eric; Picard, Emmanuel; Peyrade, David; Hadji, Emmanuel; de Fornel, Frédérique; Cluzel, Benoît

    2017-04-01

    Near-field optical forces arise from evanescent electromagnetic fields and can be advantageously used for on-chip optical trapping. In this work, we investigate how evanescent fields at the surface of photonic cavities can efficiently trap micro-objects such as polystyrene particles and bacteria. We study first the influence of trapped particle's size on the trapping potential and introduce an original optofluidic near-field optical microscopy technique. Then we analyze the rotational motion of trapped clusters of microparticles and investigate their possible use as microfluidic micro-tools such as integrated micro-flow vane. Eventually, we demonstrate efficient on-chip optical trapping of various kinds of bacteria.

  7. Red blood cells flows in rectilinear microfluidic chip.

    PubMed

    Anandan, P; Ortiz, D; Intaglietta, M; Cabrales, P J; Bucolo, M

    2015-01-01

    The red blood cells flow in a controlled environment as a microfluidic chip with a rectilinear geometry was investigated. The optical monitoring performed by an automatic Particle Image Velocimetry procedure has allowed a quantitative analysis on flow features. Various parameters such as velocity, shear rate, strain rate, vorticity, divergence were extracted. The comparisons of the results obtained from the different experiments was used for the overall understanding of the RBC movements in different conditions and the establishment of the analysis procedure.

  8. Distillation and detection of SO2 using a microfluidic chip.

    PubMed

    Ju, Wei-Jhong; Fu, Lung-Ming; Yang, Ruey-Jen; Lee, Chia-Lun

    2012-02-07

    A miniaturized distillation system is presented for separating sulfurous acid (H(2)SO(3)) into sulfur dioxide (SO(2)) and water (H(2)O). The major components of the proposed system include a microfluidic distillation chip, a power control module, and a carrier gas pressure control module. The microfluidic chip is patterned using a commercial CO(2) laser and comprises a serpentine channel, a heating zone, a buffer zone, a cooling zone, and a collection tank. In the proposed device, the H(2)SO(3) solution is injected into the microfluidic chip and is separated into SO(2) and H(2)O via an appropriate control of the distillation time and temperature. The gaseous SO(2) is then transported into the collection chamber by the carrier gas and is mixed with DI water. Finally, the SO(2) concentration is deduced from the absorbance measurements obtained using a spectrophotometer. The experimental results show that a correlation coefficient of R(2) = 0.9981 and a distillation efficiency as high as 94.6% are obtained for H(2)SO(3) solutions with SO(2) concentrations in the range of 100-500 ppm. The SO(2) concentrations of two commercial red wines are successfully detected using the developed device. Overall, the results presented in this study show that the proposed system provides a compact and reliable tool for SO(2) concentration measurement purposes.

  9. Design and research for biosensing THz microfluidic chips

    NASA Astrophysics Data System (ADS)

    Fan, Ning; Su, Bo; Zhang, Cong; Zhang, Cunlin

    2016-11-01

    Many Biomolecules vibration frequencies are in terahertz (0.1THz-10THz) frequency range, so terahertz (THz) technology is an essential tool for detecting biological molecules. However, due to terahertz strongly absorbed by water, it is difficult to detect these molecules for biological and chemical liquid samples. Therefore, we present a novel detection method by combining terahertz technology with microfluidic technology. The strong absorption of water is effectively overcome by controlling the length that terahertz passes through liquid samples. What's more, a higher signal to noise ratio is obtained through using less samples. In this paper, we designed a THz microfluidic chip that is easy to be fabricated by using the materials of Zeonor and polydimethylsiloxane (PDMS). Using terahertz time-domainspectroscopy (THz-TDS) system, we find that the chip has a high transmittance above 80% in the range from 0.2 THz to 2.6 THz. Then the THz spectra of deionized water and different kinds of solutions with different concentrations in the microfluidic chip were measured, respectively. In our research, it is found that different kinds of solutions have different transmission coefficients for THz. In addition, the THz transmission and absorption spectrum changes with the concentration of the same kind of solution.

  10. Structural Characterization of a Capillary Microfluidic Chip Using Microreflectance.

    PubMed

    Lastras-Martínez, Luis F; Balderas-Navarro, Raul E; Castro-García, Ricardo; Hernández-Vidales, Karen; Almendarez-Rodríguez, Juan; Herrera-Jasso, Rafael; Prinz, Adrian; Bergmair, Iris

    2016-10-18

    The structural characterization of capillary microfluidic chips is important for reliable applications. In particular, nondestructive diagnostic tools to assess geometrical dimensions and their correlations with control processes are of much importance, preferably if they are implemented in situ. Several techniques to accomplish this task have been reported; namely, optical coherence tomography (OCT) jointly with confocal fluorescence microscopy (CFM) to investigate internal features of lab-on-a-chip technologies. In this paper, we report on the use of a simple optical technique, based on near-normal incidence microreflectance, which allows mapping internal features of a microfluidic chip in a straightforward way. Our setup is based on a charge-coupled device camera that allows a lateral resolution of ∼2.5 µm and allows us to measure in the wavelength range of 640-750 nm. The technique takes advantage of the Fabry-Perot interferences features in the reflectance spectra, which are further analyzed by a discrete Fourier transform. In this way, the amplitude of the Fourier coefficients is modulated by the presence of a microfluidic channel.

  11. Note: A microfluidic chip setup for capillarity-assisted particle assembly

    NASA Astrophysics Data System (ADS)

    Klein, M. J. K.; Kuemin, C.; Tamulevicius, T.; Manning, M.; Wolf, H.

    2012-08-01

    We developed a microfluidic chip setup for capillarity-assisted particle assembly (CAPA). A capillary bridge is formed between the aperture of a silicon chip and the assembly template. The bridge is fed with particle suspension through a microfluidic channel on the chip top side. With this setup, we can control the particle assembly location and tune the suspension composition during particle assembly. In this note, we describe the chip setup, the CAPA process using the microfluidic chip, and results of complex particle assemblies, such as composite particle arrays and particle gradients, that could not be obtained using a conventional CAPA setup.

  12. High Voltage Dielectrophoretic and Magnetophoretic Hybrid Integrated Circuit / Microfluidic Chip

    PubMed Central

    Issadore, David; Franke, Thomas; Brown, Keith A.; Hunt, Thomas P.; Westervelt, Robert M.

    2010-01-01

    A hybrid integrated circuit (IC) / microfluidic chip is presented that independently and simultaneously traps and moves microscopic objects suspended in fluid using both electric and magnetic fields. This hybrid chip controls the location of dielectric objects, such as living cells and drops of fluid, on a 60 × 61 array of pixels that are 30 × 38 μm2 in size, each of which can be individually addressed with a 50 V peak-to-peak, DC to 10 MHz radio frequency voltage. These high voltage pixels produce electric fields above the chip’s surface with a magnitude , resulting in strong dielectrophoresis (DEP) forces . Underneath the array of DEP pixels there is a magnetic matrix that consists of two perpendicular sets of 60 metal wires running across the chip. Each wire can be sourced with 120 mA to trap and move magnetically susceptible objects using magnetophoresis (MP). The DEP pixel array and magnetic matrix can be used simultaneously to apply forces to microscopic objects, such as living cells or lipid vesicles, that are tagged with magnetic nanoparticles. The capabilities of the hybrid IC / microfluidic chip demonstrated in this paper provide important building blocks for a platform for biological and chemical applications. PMID:20625468

  13. Microfluidic-Based sample chips for radioactive solutions

    SciTech Connect

    Tripp, J. L.; Law, J. D.; Smith, T. E.; Rutledge, V. J.; Bauer, W. F.; Ball, R. D.; Hahn, P. A.

    2015-01-01

    Historical nuclear fuel cycle process sampling techniques required sample volumes ranging in the tens of milliliters. The radiation levels experienced by analytical personnel and equipment, in addition to the waste volumes generated from analysis of these samples, have been significant. These sample volumes also impacted accountability inventories of required analytes during process operations. To mitigate radiation dose and other issues associated with the historically larger sample volumes, a microcapillary sample chip was chosen for further investigation. The ability to obtain microliter volume samples coupled with a remote automated means of sample loading, tracking, and transporting to the analytical instrument would greatly improve analytical efficiency while reducing both personnel exposure and radioactive waste volumes. Sample chip testing was completed to determine the accuracy, repeatability, and issues associated with the use of microfluidic sample chips used to supply µL sample volumes of lanthanide analytes dissolved in nitric acid for introduction to an analytical instrument for elemental analysis.

  14. Microfluidic-Based Sample Chips for Radioactive Solutions

    SciTech Connect

    Tripp, J. L.; Law, J. D.; Smith, T. E.; Rutledge, V. J.; Bauer, W. F.; Ball, R. D.; Hahn, P. A.

    2014-02-01

    Historical nuclear fuel cycle process sampling techniques required sample volumes ranging in the tens of milliliters. The radiation levels experienced by analytical personnel and equipment, in addition to the waste volumes generated from analysis of these samples, have been significant. These sample volumes also impacted accountability inventories of required analytes during process operations. To mitigate radiation dose and other issues associated with the historically larger sample volumes, a microcapillary sample chip was chosen for further investigation. The ability to obtain microliter volume samples coupled with a remote automated means of sample loading, tracking, and transporting to the analytical instrument would greatly improve analytical efficiency while reducing both personnel exposure and radioactive waste volumes. Sample chip testing was completed to determine the accuracy, repeatability, and issues associated with the use of microfluidic sample chips used to supply µL sample volumes of lanthanide analytes dissolved in nitric acid for introduction to an analytical instrument for elemental analysis.

  15. Microfluidic Chip Coupled with Thermal Desorption Atmospheric Pressure Ionization Mass Spectrometry

    PubMed Central

    Chang, Chia-Hsien; Chen, Tsung-Yi; Chen, Yu-Chie

    2014-01-01

    Microfluidic chips have been used as platforms for a diversity of research purposes such as for separation and micro-reaction. One of the suitable detectors for microfluidic chip is mass spectrometry. Because microfluidic chips are generally operated in an open air condition, mass spectrometry coupled with atmospheric pressure ion sources can suit the requirement with minimum compromise. In this study, we develop a new interface to couple a microfluidic chip with mass spectrometry. A capillary tip coated with a layer of graphite, capable of absorbing energy of near-infrared (NIR) light is used to interface microfluidic chip with mass spectrometry. An NIR laser diode (λ=808 nm) is used to irradiate the capillary tip for assisting the generation of spray from the eluent of the microfluidic chip. An electrospray is provided to fuse with the spray generated from the microfluidic chip for post-ionization. Transesterification is used as the example to demonstrate the feasibility of using this interface to couple microfluidic chip with mass spectrometry. PMID:26839753

  16. Integrated on-chip mass spectrometry reaction monitoring in microfluidic devices containing porous polymer monolithic columns.

    PubMed

    Dietze, C; Schulze, S; Ohla, S; Gilmore, K; Seeberger, P H; Belder, D

    2016-09-21

    Chip-based microfluidics enable the seamless integration of different functions into single devices. Here, we present microfluidic chips containing porous polymer monolithic columns as a means to facilitate chemical transformations as well as both downstream chromatographic separation and mass spectrometric analysis. Rapid liquid phase lithography prototyping creates the multifunctional device economically.

  17. Polydimethylsiloxane-based conducting composites and their applications in microfluidic chip fabrication

    PubMed Central

    Gong, Xiuqing; Wen, Weijia

    2009-01-01

    This paper reviews the design and fabrication of polydimethylsiloxane (PDMS)-based conducting composites and their applications in microfluidic chip fabrication. Owing to their good electrical conductivity and rubberlike elastic characteristics, these composites can be used variously in soft-touch electronic packaging, planar and three-dimensional electronic circuits, and in-chip electrodes. Several microfluidic components fabricated with PDMS-based composites have been introduced, including a microfluidic mixer, a microheater, a micropump, a microdroplet controller, as well as an all-in-one microfluidic chip. PMID:19693388

  18. Microfluidic-chip platform for cell sorting

    NASA Astrophysics Data System (ADS)

    Malik, Sarul; Balyan, Prerna; Akhtar, J.; Agarwal, Ajay

    2016-04-01

    Cell sorting and separation are considered to be very crucial preparatory steps for numerous clinical diagnostics and therapeutics applications in cell biology research arena. Label free cell separation techniques acceptance rate has been increased to multifold by various research groups. Size based cell separation method focuses on the intrinsic properties of the cell which not only avoids clogging issues associated with mechanical and centrifugation filtration methods but also reduces the overall cost for the process. Consequentially flow based cell separation method for continuous flow has attracted the attention of millions. Due to the realization of structures close to particle size in micro dimensions, the microfluidic devices offer precise and rapid particle manipulation which ultimately leads to an extraordinary cell separation results. The proposed microfluidic device is fabricated to separate polystyrene beads of size 1 µm, 5 µm, 10 µm and 20 µm. The actual dimensions of blood corpuscles were kept in mind while deciding the particle size of polystyrene beads which are used as a model particles for study.

  19. A novel monolithic fabrication method for a plastic microfluidic chip with liquid interconnecting ports

    NASA Astrophysics Data System (ADS)

    Lee, Bong-Kee; Kwon, Tai Hun

    2010-10-01

    In the present study, a novel monolithic fabrication method was developed for the manufacturing of a plastic microfluidic chip with liquid interconnecting ports. As the present method can realize both interconnecting ports and through holes, which are essential components for the delivery of working fluids, in the plastic microfluidic chip, no additional processes and external ports are required. Furthermore, the connection of external silicone tubing can be simply achieved by utilizing an elastic deformation of the used tubing. As one representative example, a microinjection molding of a prototype microfluidic chip having two types of interconnecting ports was demonstrated. After obtaining upper and lower plates by the microinjection molding process utilizing mold cores with pin structures, the thermal bonding of the molded plates was carried out, resulting in the prototype plastic microfluidic chip with interconnecting ports. From microfluidic experiments using the fabricated prototype, it was found that the present method could be quite useful in various microfluidic applications.

  20. Surface enhanced Raman spectroscopy for microfluidic pillar arrayed separation chips

    SciTech Connect

    Taylor, Lisa; Kirchner, Teresa B; Lavrik, Nickolay V; Sepaniak, Michael

    2012-01-01

    Numerous studies have addressed the challenges of implementing miniaturized microfluidic platforms for chemical and biological separation applications. However, the integration of real time detection schemes capable of providing valuable sample information under continuous, ultra low volume flow regimes has not fully been addressed. In this report we present a chip based chromatography system comprising of a pillar array separation column followed by a reagent channel for passive mixing of a silver colloidal solution into the eluent stream to enable surface enhanced Raman spectroscopy (SERS) detection. Our design is the first integrated chip based microfluidic device to combine pressure driven separation capability with real time SERS detection. With this approach we demonstrate the ability to collect distinctive SERS spectra with or without complete resolution of chromatographic bands. Computational fluidic dynamic (CFD) simulations are used to model the diffusive mixing behavior and velocity profiles of the two confluent streams in the microfluidic channels. We evaluate the SERS spectral band intensity and chromatographic efficiency of model analytes with respect to kinetic factors as well as signal acquisition rates. Additionally, we discuss the use of a pluronic modified silver colloidal solution as a means of eliminating contamination generally caused by nanoparticle adhesion to channel surfaces.

  1. Fabrication and multifunction integration of microfluidic chips by femtosecond laser direct writing.

    PubMed

    Xu, Bin-Bin; Zhang, Yong-Lai; Xia, Hong; Dong, Wen-Fei; Ding, Hong; Sun, Hong-Bo

    2013-05-07

    In the pursuit of modern microfluidic chips with multifunction integration, micronanofabrication techniques play an increasingly important role. Despite the fact that conventional fabrication approaches such as lithography, imprinting and soft lithography have been widely used for the preparation of microfluidic chips, it is still challenging to achieve complex microfluidic chips with multifunction integration. Therefore, novel micronanofabrication approaches that could be used to achieve this end are highly desired. As a powerful 3D processing tool, femtosecond laser fabrication shows great potential to endow general microfluidic chips with multifunctional units. In this review, we briefly introduce the fundamental principles of femtosecond laser micronanofabrication. With the help of laser techniques, both the preparation and functionalization of advanced microfluidic chips are summarized. Finally, the current challenges and future perspective of this dynamic field are discussed based on our own opinion.

  2. The RootChip: an integrated microfluidic chip for plant science.

    PubMed

    Grossmann, Guido; Guo, Woei-Jiun; Ehrhardt, David W; Frommer, Wolf B; Sit, Rene V; Quake, Stephen R; Meier, Matthias

    2011-12-01

    Studying development and physiology of growing roots is challenging due to limitations regarding cellular and subcellular analysis under controlled environmental conditions. We describe a microfluidic chip platform, called RootChip, that integrates live-cell imaging of growth and metabolism of Arabidopsis thaliana roots with rapid modulation of environmental conditions. The RootChip has separate chambers for individual regulation of the microenvironment of multiple roots from multiple seedlings in parallel. We demonstrate the utility of The RootChip by monitoring time-resolved growth and cytosolic sugar levels at subcellular resolution in plants by a genetically encoded fluorescence sensor for glucose and galactose. The RootChip can be modified for use with roots from other plant species by adapting the chamber geometry and facilitates the systematic analysis of root growth and metabolism from multiple seedlings, paving the way for large-scale phenotyping of root metabolism and signaling.

  3. Microfluidic plastic interconnects for multibioanalysis chip modules

    NASA Astrophysics Data System (ADS)

    Man, Piu Francis; Jones, Darren K.; Mastrangelo, Carlos H.

    1997-09-01

    This paper describes the fabrication and testing of plastic fluidic connectors suitable for the assembly of multichip microfluidic systems. The connectors basically consist of a series of 50-200 X 20 micrometers 2 capillaries embedded in a 70 micrometers -thick flexible polyimide substrate with large access holes ion both ends. The capillary walls and the connector exterior are coated with a thin layer of p- xylylene providing a high degree of chemical inertness and biocompatibility. These flexible connectors are inherently planar for ease of connection to flat substrates and are constructed using conventional batch lithographic techniques. The connector flow characteristics were tested in nitrogen gas and water. Multiple channel connectors with 3 and 5 capillaries 1.3-4.0 cm-long were constructed successfully.

  4. Microfluidic Chip for the Photocatalytic Production of Active Chlorine.

    PubMed

    Elmas, Sait; Ambroz, Filip; Chugh, Dipankar; Nann, Thomas

    2016-05-17

    Active chlorine is the most powerful microbicidal reagent in swimming pools, potable water, hospitals, and medical surgeries. Its production mainly relies on reactive inorganic intermediates and electrochemical methods that involve undesired waste products and high energy as well as material costs. In this study, we fabricated a low-cost chip based on sputter-coated thin films of silver (Ag) that acted as recyclable and effective photoelectrode for the photocatalytic production of active chlorine (HOCl) from aqueous media and artificial sunlight. The photoelectrode was electrochemically activated to AgCl at low overpotentials between 0.2 and 0.4 V vs Ag|AgCl (3 M KCl) and photocatalytically reduced to Ag(0) for 15 consecutive cycles, showing the electrode still being active. However, because of poor adhesion properties on the selected substrates, degradation effects were observed over time. Furthermore, the Ag@AgCl photoelectrode was integrated into a microfluidic chip, and we showed for the first time a light-driven microfluidic chip generating a constant stream of active chlorine.

  5. A microfluidic chip for studying the reproduction of Enteromorpha prolifera.

    PubMed

    Xu, Zhixuan; Liu, Qi; Zhang, Xinlian; Huang, Xuxiong; He, Peimin; Liu, Sixiu; Sui, Guodong

    2016-11-01

    In recent years, green tides caused by water eutrophication, has brought serious environmental problems. Enteromorpha prolifera (E. prolifera), an opportunistic macroalgae, is one of the main source contributing to the formation of green tides. It has been estimated that the excessive growth of E. prolifera is closely related to various reproductive ways of germ cells which are at the micrometer scale. Here we report a microfluidic device named Germ Cell Capture Chip (GCChip) to investigate the E. prolifera reproductive mechanism. GCChip integrates the functions of algal growing, and the release, capture and selective culture of germ cells. Automatic separation and capture of germ cells on the chip allows to study germ cells' response to different stimuli. The novel device greatly facilitates long-term live-cell imaging at cellular resolution and implements the rapid and accurate exchange of growth medium without manual intervention. Results showed that the starting time of germ cell releases were earlier on the chip than that of traditional experiments with more concentrated breakout. Moreover, GCChip can be widely applied on the study of other algae. The study of algae growth process, including the elongation of somatic cell, the generation, and the release of reproductive cells, can all be improved by using this microfluidic platform. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. A microwave resonator integrated on a polymer microfluidic chip

    NASA Astrophysics Data System (ADS)

    Kiss, S. Z.; Rostas, A. M.; Heidinger, L.; Spengler, N.; Meissner, M. V.; MacKinnon, N.; Schleicher, E.; Weber, S.; Korvink, J. G.

    2016-09-01

    We describe a novel stacked split-ring type microwave (MW) resonator that is integrated into a 10 mm by 10 mm sized microfluidic chip. A straightforward and scalable batch fabrication process renders the chip suitable for single-use applications. The resonator volume can be conveniently loaded with liquid sample via microfluidic channels patterned into the mid layer of the chip. The proposed MW resonator offers an alternative solution for compact in-field measurements, such as low-field magnetic resonance (MR) experiments requiring convenient sample exchange. A microstrip line was used to inductively couple MWs into the resonator. We characterised the proposed resonator topology by electromagnetic (EM) field simulations, a field perturbation method, as well as by return loss measurements. Electron paramagnetic resonance (EPR) spectra at X-band frequencies were recorded, revealing an electron-spin sensitivity of 3.7 ·1011spins ·Hz - 1 / 2G-1 for a single EPR transition. Preliminary time-resolved EPR experiments on light-induced triplet states in pentacene were performed to estimate the MW conversion efficiency of the resonator.

  7. A microwave resonator integrated on a polymer microfluidic chip.

    PubMed

    Kiss, S Z; Rostas, A M; Heidinger, L; Spengler, N; Meissner, M V; MacKinnon, N; Schleicher, E; Weber, S; Korvink, J G

    2016-09-01

    We describe a novel stacked split-ring type microwave (MW) resonator that is integrated into a 10mm by 10mm sized microfluidic chip. A straightforward and scalable batch fabrication process renders the chip suitable for single-use applications. The resonator volume can be conveniently loaded with liquid sample via microfluidic channels patterned into the mid layer of the chip. The proposed MW resonator offers an alternative solution for compact in-field measurements, such as low-field magnetic resonance (MR) experiments requiring convenient sample exchange. A microstrip line was used to inductively couple MWs into the resonator. We characterised the proposed resonator topology by electromagnetic (EM) field simulations, a field perturbation method, as well as by return loss measurements. Electron paramagnetic resonance (EPR) spectra at X-band frequencies were recorded, revealing an electron-spin sensitivity of 3.7·10(11)spins·Hz(-1/2)G(-1) for a single EPR transition. Preliminary time-resolved EPR experiments on light-induced triplet states in pentacene were performed to estimate the MW conversion efficiency of the resonator.

  8. Microfluidics on liquid handling stations (μF-on-LHS): an industry compatible chip interface between microfluidics and automated liquid handling stations.

    PubMed

    Waldbaur, Ansgar; Kittelmann, Jörg; Radtke, Carsten P; Hubbuch, Jürgen; Rapp, Bastian E

    2013-06-21

    We describe a generic microfluidic interface design that allows the connection of microfluidic chips to established industrial liquid handling stations (LHS). A molding tool has been designed that allows fabrication of low-cost disposable polydimethylsiloxane (PDMS) chips with interfaces that provide convenient and reversible connection of the microfluidic chip to industrial LHS. The concept allows complete freedom of design for the microfluidic chip itself. In this setup all peripheral fluidic components (such as valves and pumps) usually required for microfluidic experiments are provided by the LHS. Experiments (including readout) can be carried out fully automated using the hardware and software provided by LHS manufacturer. Our approach uses a chip interface that is compatible with widely used and industrially established LHS which is a significant advancement towards near-industrial experimental design in microfluidics and will greatly facilitate the acceptance and translation of microfluidics technology in industry.

  9. Flow lithography in ultraviolet-curable polydimethylsiloxane microfluidic chips.

    PubMed

    Kim, Junbeom; An, Heseong; Seo, Yoojin; Jung, Youngmee; Lee, Jong Suk; Choi, Nakwon; Bong, Ki Wan

    2017-03-01

    Flow Lithography (FL) is the technique used for the synthesis of hydrogel microparticles with various complex shapes and distinct chemical compositions by combining microfluidics with photolithography. Although polydimethylsiloxane (PDMS) has been used most widely as almost the sole material for FL, PDMS microfluidic chips have limitations: (1) undesired shrinkage due to the thermal expansion of masters used for replica molding and (2) interfacial delamination between two thermally cured PDMS layers. Here, we propose the utilization of ultraviolet (UV)-curable PDMS (X-34-4184) for FL as an excellent alternative material of the conventional PDMS. Our proposed utilization of the UV-curable PDMS offers three key advantages, observed in our study: (1) UV-curable PDMS exhibited almost the same oxygen permeability as the conventional PDMS. (2) The almost complete absence of shrinkage facilitated the fabrication of more precise reverse duplication of microstructures. (3) UV-cured PDMS microfluidic chips were capable of much stronger interfacial bonding so that the burst pressure increased to ∼0.9 MPa. Owing to these benefits, we demonstrated a substantial improvement of productivity in synthesizing polyethylene glycol diacrylate microparticles via stop flow lithography, by applying a flow time (40 ms) an order of magnitude shorter. Our results suggest that UV-cured PDMS chips can be used as a general platform for various types of flow lithography and also be employed readily in other applications where very precise replication of structures on micro- or sub-micrometer scales and/or strong interfacial bonding are desirable.

  10. ITP of lanthanides in microfluidic PMMA chip.

    PubMed

    Cong, Yongzheng; Bottenus, Danny; Liu, Bingwen; Clark, Sue B; Ivory, Cornelius F

    2014-03-01

    An ITP separation of eight lanthanides on a serpentine PMMA microchip with a tee junction and a 230-mm-long serpentine channel is described. The cover of the PMMA chip is 175 μm thick so that a C(4) D in microchip mode can be used to detect the lanthanides as they migrate through the microchannel. Acetate and α-hydroxyisobutyric acid are used as complexing agents to increase the electrophoretic mobility difference between the lanthanides. Eight lanthanides are concentrated within ∼ 6 min by ITP in the microchip using 10 mM ammonium acetate at pH 4.5 as the leading electrolyte and 10 mM acetic acid at ∼ pH 3.0 as the terminating electrolyte. In addition, a 2D numerical simulation of the lanthanides undergoing ITP in the microchip is compared with experimental results using COMSOL Multiphysics v4.3a.

  11. Microfluidics without channels: highly-flexible synthesis on a digital-microfluidic chip for production of diverse PET tracers

    SciTech Connect

    Van Dam, Robert Michael

    2010-09-01

    Positron emission tomography (PET) imaging is used for fundamental studies of living biological organisms and microbial ecosystems in applications ranging from biofuel production to environmental remediation to the study, diagnosis, and treatment monitoring of human disease. Routine access to PET imaging, to monitor biochemical reactions in living organisms in real time, could accelerate a broad range of research programs of interest to DOE. Using PET requires access to short-lived radioactive-labeled compounds that specifically probe the desired living processes. The overall aims of this project were to develop a miniature liquid-handling technology platform (called “microfluidics”) that increases the availability of diverse PET probes by reducing the cost and complexity of their production. Based on preliminary experiments showing that microfluidic chips can synthesis such compounds, we aimed to advance this technology to improve its robustness, increase its flexibility for a broad range of probes, and increase its user-friendliness. Through the research activities of this project, numerous advances were made; Tools were developed to enable the visualization of radioactive materials within microfluidic chips; Fundamental advances were made in the microfluidic chip architecture and fabrication process to increase its robustness and reliability; The microfluidic chip technology was shown to produce useful quantities of an example PET probes, and methods to further increase the output were successfully pursued; A “universal” chip was developed that could produce multiple types of PET probes, enabling the possibility of “on demand” synthesis of different probes; and Operation of the chip was automated to ensure minimal radiation exposure to the operator Based on the demonstrations of promising technical feasibility and performance, the microfluidic chip technology is currently being commercialized. It is anticipated that costs of microfluidic chips can be

  12. Flexible packaging of solid-state integrated circuit chips with elastomeric microfluidics

    PubMed Central

    Zhang, Bowei; Dong, Quan; Korman, Can E.; Li, Zhenyu; Zaghloul, Mona E.

    2013-01-01

    A flexible technology is proposed to integrate smart electronics and microfluidics all embedded in an elastomer package. The microfluidic channels are used to deliver both liquid samples and liquid metals to the integrated circuits (ICs). The liquid metals are used to realize electrical interconnects to the IC chip. This avoids the traditional IC packaging challenges, such as wire-bonding and flip-chip bonding, which are not compatible with current microfluidic technologies. As a demonstration we integrated a CMOS magnetic sensor chip and associate microfluidic channels on a polydimethylsiloxane (PDMS) substrate that allows precise delivery of small liquid samples to the sensor. Furthermore, the packaged system is fully functional under bending curvature radius of one centimetre and uniaxial strain of 15%. The flexible integration of solid-state ICs with microfluidics enables compact flexible electronic and lab-on-a-chip systems, which hold great potential for wearable health monitoring, point-of-care diagnostics and environmental sensing among many other applications.

  13. Flexible packaging of solid-state integrated circuit chips with elastomeric microfluidics

    NASA Astrophysics Data System (ADS)

    Zhang, Bowei; Dong, Quan; Korman, Can E.; Li, Zhenyu; Zaghloul, Mona E.

    2013-01-01

    A flexible technology is proposed to integrate smart electronics and microfluidics all embedded in an elastomer package. The microfluidic channels are used to deliver both liquid samples and liquid metals to the integrated circuits (ICs). The liquid metals are used to realize electrical interconnects to the IC chip. This avoids the traditional IC packaging challenges, such as wire-bonding and flip-chip bonding, which are not compatible with current microfluidic technologies. As a demonstration we integrated a CMOS magnetic sensor chip and associate microfluidic channels on a polydimethylsiloxane (PDMS) substrate that allows precise delivery of small liquid samples to the sensor. Furthermore, the packaged system is fully functional under bending curvature radius of one centimetre and uniaxial strain of 15%. The flexible integration of solid-state ICs with microfluidics enables compact flexible electronic and lab-on-a-chip systems, which hold great potential for wearable health monitoring, point-of-care diagnostics and environmental sensing among many other applications.

  14. Microfluidic cytometers with integrated on-chip optical systems for red blood cell and platelet counting.

    PubMed

    Zhao, Yingying; Li, Qin; Hu, Xiaoming; Lo, Yuhwa

    2016-11-01

    A microfluidic cytometer with integrated on-chip optical systems was designed for red blood cell (RBC) and platelet (PLT) counting. The design, fabrication, and characterization of the microfluidic cytometer with on-chip optical signal detection were described. With process using only a single mask, the device that integrates optical fibers and on-chip microlens with microfluidic channels on a polydimethylsiloxane layer by standard soft photolithography. This compact structure increased the sensitivity of the device and eliminated time-consuming free-space optical alignments. The microfluidic cytometer was used to count red blood cells and platelets. Forward scatter and extinction were collected simultaneously for each cell. Experimental results indicated that the microfluidic cytometer exhibited comparable performance with a conventional cytometer and demonstrated superior capacity to detect on-chip optical signals in a highly compact, simple, truly portable, and low-cost format that is well suitable for point-of-care clinical diagnostics.

  15. Microfluidic chips with reversed-phase monoliths for solid phase extraction and on-chip labeling.

    PubMed

    Nge, Pamela N; Pagaduan, Jayson V; Yu, Ming; Woolley, Adam T

    2012-10-26

    The integration of sample preparation methods into microfluidic devices provides automation necessary for achieving complete micro total analysis systems. We have developed a technique that combines on-chip sample enrichment with fluorescence labeling and purification. Polymer monoliths made from butyl methacrylate were fabricated in cyclic olefin copolymer microdevices and used for solid phase extraction. We studied the retention of fluorophores, amino acids and proteins on these columns. The retained samples were subsequently labeled with both Alexa Fluor 488 and Chromeo P503, and unreacted dye was rinsed off the column before sample elution. Additional purification was obtained from the differential retention of proteins and fluorescent labels. A linear relation between the eluted peak areas and concentrations of on-chip labeled heat shock protein 90 samples demonstrated the utility of this method for on-chip quantitation. Our fast and simple method of simultaneously concentrating and labeling samples on-chip is compatible with miniaturization and desirable for automated analysis.

  16. Microfluidics and photonics for Bio-System-on-a-Chip: A review of advancements in technology towards a microfluidic flow cytometry chip

    PubMed Central

    Godin, Jessica; Chen, Chun-Hao; Cho, Sung Hwan; Qiao, Wen; Tsai, Frank; Lo, Yu-Hwa

    2009-01-01

    Microfluidics and photonics come together to form a field commonly referred to as ‘optofluidics’. Flow cytometry provides the field with a technology base from which both microfluidic and photonic components be developed and integrated into a useful device. This article reviews some of the more recent developments to familiarize a reader with the current state of the technologies and also highlights the requirements of the device and how researchers are working to meet these needs. A microfluidic flow cytometer protoype employing on-chip lenses for illumination and light collection in conjunction with a microfluidic sample flow system for device miniaturization. PMID:19343660

  17. Development of a microfluidic chip-based plasmid miniprep.

    PubMed

    Northrup, Victoria A; Backhouse, Christopher J; Glerum, D Moira

    2010-07-15

    Plasmids are the workhorse of contemporary molecular biology, serving as vectors in the multitude of molecular cloning approaches now available. Plasmid minipreps are a routine and essential means of extracting plasmid DNA from bacteria, such as Escherichia coli, for identification, characterization, and further manipulation. Although there have been many approaches described and miniprep kits are commercially available, traditional minipreps typically require more than 16h, including the time needed for bacterial cell culture. Here we describe the development of a microfluidic chip (MFC)-based miniprep that uses on-chip lysis and trapping of large DNA in agarose to differentially separate plasmid DNA from the bacterial chromosome. Our approach greatly decreases both the time required for the miniprep itself and the time required for growth of the bacterial cultures because our on-chip miniprep uses 10(5) times fewer E. coli cells. Because the quality of the isolated plasmid is comparable to that obtained using conventional miniprep protocols, this approach allows growth of E. coli and isolation of plasmid within hours, thereby making it ideal for rapid screening approaches. This MFC-based miniprep, coupled with recently demonstrated on-chip transfection capabilities, lays the groundwork for seamless manipulation of plasmids on MFC platforms.

  18. Polymeric nanofiber web-based artificial renal microfluidic chip.

    PubMed

    Lee, K H; Kim, D J; Min, B G; Lee, S H

    2007-08-01

    In this paper, we present a new method for the creation of a smaller dialyzer and do so by incorporating polymeric nanofiber web, which is known to have good filtration efficiency for broad particle sizes, into a poly (dimethylsiloxane)-based microplatform. We have developed a process that makes possible the efficient production of polyethersulfone and polyurethane nanofiber web and that, itself, incorporates an electrospinning method. We have combined the nanofiber web with the PDMS-based microfluidic platform to create a chip-based portable hemodialysis system. With the dialyzing chip, we evaluated the filtration capability of molecules in broad ranges of sizes and compared the filtration capability of nanofiber membranes with that of PES and polyvinylidene fluoride porous membranes (sheet type): we discovered that the nanofiber membranes have better filtration performance than the other membranes. Blood cells were not mechanically affected during their filtration and their transportation through the chip. In conclusion, we have demonstrated the feasibility of chip-based hemodialysis, and we expect that our method suggested in this paper will be applied to the development of small light-weight dialyzers for the realization of portable hemodialysis systems.

  19. Calibration of optical coherence tomography angiography with a microfluidic chip

    NASA Astrophysics Data System (ADS)

    Su, Johnny P.; Chandwani, Rahul; Gao, Simon S.; Pechauer, Alex D.; Zhang, Miao; Wang, Jie; Jia, Yali; Huang, David; Liu, Gangjun

    2016-08-01

    A microfluidic chip with microchannels ranging from 8 to 96 μm was used to mimic blood vessels down to the capillary level. Blood flow within the microfluidic channels was analyzed with split-spectrum amplitude-decorrelation angiography (SSADA)-based optical coherence tomography (OCT) angiography. It was found that the SSADA decorrelation value was related to both blood flow speed and channel width. SSADA could differentiate nonflowing blood inside the microfluidic channels from static paper. The SSADA decorrelation value was approximately linear with blood flow velocity up to a threshold Vsat of 5.83±1.33 mm/s (mean±standard deviation over the range of channel widths). Beyond this threshold, it approached a saturation value Dsat. Dsat was higher for wider channels, and approached a maximum value Dsm as the channel width became much larger than the beam focal spot diameter. These results indicate that decorrelation values (flow signal) in capillary networks would be proportional to both flow velocity and vessel caliber but would be capped at a saturation value in larger blood vessels. These findings are useful for interpretation and quantification of clinical OCT angiography results.

  20. The Promise of Macromolecular Crystallization in Micro-fluidic Chips

    NASA Technical Reports Server (NTRS)

    vanderWoerd, Mark; Ferree, Darren; Pusey, Marc

    2003-01-01

    Micro-fluidics, or lab on a chip technology, is proving to be a powerful, rapid, and efficient approach to a wide variety of bio-analytical and microscale bio-preparative needs. The low materials consumption, combined with the potential for packing a large number of experiments in a few cubic centimeters, makes it an attractive technique for both initial screening and subsequent optimization of macromolecular crystallization conditions. Screening operations, which require equilibrating macromolecule solution with a standard set of premixed solutions, are relatively straightforward and have been successfully demonstrated in a micro-fluidics platform. More complex optimization methods, where crystallization solutions are independently formulated from a range of stock solutions, are considerably more complex and have yet to be demonstrated. To be competitive with either approach, a micro-fluidics system must offer ease of operation, be able to maintain a sealed environment over several weeks to months, and give ready access for the observation of crystals as they are grown.

  1. The Promise of Macromolecular Crystallization in Micro-fluidic Chips

    NASA Technical Reports Server (NTRS)

    vanderWoerd, Mark; Ferree, Darren; Pusey, Marc

    2003-01-01

    Micro-fluidics, or lab on a chip technology, is proving to be a powerful, rapid, and efficient approach to a wide variety of bio-analytical and microscale bio-preparative needs. The low materials consumption, combined with the potential for packing a large number of experiments in a few cubic centimeters, makes it an attractive technique for both initial screening and subsequent optimization of macromolecular crystallization conditions. Screening operations, which require equilibrating macromolecule solution with a standard set of premixed solutions, are relatively straightforward and have been successfully demonstrated in a micro-fluidics platform. More complex optimization methods, where crystallization solutions are independently formulated from a range of stock solutions, are considerably more complex and have yet to be demonstrated. To be competitive with either approach, a micro-fluidics system must offer ease of operation, be able to maintain a sealed environment over several weeks to months, and give ready access for the observation of crystals as they are grown.

  2. Optical two-beam trap in a polymer microfluidic chip

    NASA Astrophysics Data System (ADS)

    Espina Palanco, Marta; Catak, Darmin; Marie, Rodolphe; Matteucci, Marco; Bilenberg, Brian; Kristensen, Anders; Berg-Sørensen, Kirstine

    2016-09-01

    An optical two-beam trap, composed from two counter propagating laser beams, is an interesting setup due to the ability of the system to trap, hold, and stretch soft biological objects like vesicles or single cells. Because of this functionality, the system was also named "the optical stretcher" by Jochen Guck, Josep Käs and co-workers some 15 years ago. In a favorable setup, the two opposing laser beams meet with equal intensities in the middle of a fluidic channel in which cells may flow past, be trapped, stretched, and allowed to move on, giving the promise of a high throughput device. Yet, single beam optical traps, aka optical tweezers, by far outnumber the existing optical stretchers in research labs throughout the world. The ability to easily construct an optical stretcher setup in a low-cost material would possibly imply more frequent use of the optical stretching technique. Here, we will outline the design, the production procedures, and results obtained in a fiber-based experimental setup built within an injection molded microfluidic polymer chip. The microfluidic chip is constructed with a three layer technology in which we ensure both horizontal and vertical focusing of the cells we wish to trap, thereby preventing too many cells to flow below the line of focus of the two counter propagating laser beams that are positioned perpendicular to the direction of flow of the cells. Results will be compared to that from other designs from previous work in the group.

  3. Polymethylhydrosiloxane (PMHS) as a functional material for microfluidic chips

    NASA Astrophysics Data System (ADS)

    Lee, S. J.; Goedert, M.; Matyska, M. T.; Ghandehari, E. M.; Vijay, M.; Pesek, J. J.

    2008-02-01

    Polymethylhydrosiloxane (PMHS) has been investigated as a candidate material for microfluidic chips. The ability to modify the surface of PMHS by hydrosilation is particularly advantageous for separation processes. The chemical modification of PMHS is verified by diffuse reflectance infrared Fourier transform (DRIFT) analysis, and the modified PMHS is shown to be stable when exposed to extreme pH conditions between 2 and 9. Spectrophotometer measurements show that PMHS exhibits over 40% transmittance for ultraviolet (UV) wavelength as low as 220 nm, indicating viability for sensor applications based on UV absorption. The UV transmittance is furthermore observed to be insensitive to thickness for specimens tested between 1.6 mm and 6.4 mm thick. Full curing of PMHS liquid resin occurs between 48 and 72 h at 110 °C with no secondary additives. Casting of microscale features is achieved by using soft lithography methods similar to established techniques for fabrication based on polydimethylsiloxane (PDMS). Microchannels approximately 100 µm wide and 50 µm deep are also demonstrated by carbon dioxide laser ablation, with uniform channels produced using an energy dose of 0.2 mJ mm-1 with respect to line length. Other basic functional requirements for microfluidic chips are discussed, including the ability to bond PMHS substrates by plasma treatment.

  4. Fast prototyping of injection molded polymer microfluidic chips

    NASA Astrophysics Data System (ADS)

    Steen Hansen, Thomas; Selmeczi, David; Larsen, Niels B.

    2010-01-01

    We present fast prototyping of injection molding tools by the definition of microfluidic structures in a light-curable epoxy (SU-8) directly on planar nickel mold inserts. Optimized prototype mold structures could withstand injection molding of more than 300 replicas in cyclic olefin copolymer (COC) without any signs of failure or release. The key parameters to avoid mold failure are maximum adhesion strength of the epoxy to the nickel insert and minimum interfacial energy of the epoxy pattern to the molded polymer. Optimal molding of microstructures with vertical sidewalls was found for nickel inserts pre-coated by silicon oxide before applying the structured epoxy, followed by coating of the epoxy by a fluorocarbon layer prior to injection molding. Further improvements in the mold stability were observed after homogeneous coating of the patterned epoxy by a second reflowed layer of epoxy, likely due to the resulting reduction in sidewall steepness. We employed the latter method for injection molding bondable polymer microfluidic chips with integrated conducting polymer electrode arrays that permitted the culture and on-chip analysis of cell spreading by impedance spectroscopy.

  5. An integrated microfluidic chip for the analysis of biochemical reactions by MALDI mass spectrometry.

    PubMed

    Lee, Sang-Ho; Lee, Chang-Soo; Kim, Byung-Gee; Kim, Yong-Kweon

    2008-02-01

    Using an integrated microfluidic chip combined with mass spectrometry is an attractive method for parallel and multiple analyses because of its inherent simplicity, low sample consumption, and high sensitivity. To realize an effective microfluidic chip for the rapid analysis of biochemical reactions by matrix assisted laser desorption/ionization (MALDI)-mass spectrometry (MS), the basic operations on microfluids, namely loading, metering, cutting, transporting, mixing, and injecting, must be integrated. This study describes an integrated microfluidic chip with MALDI-MS that performs the on-chip analysis of biochemical reactions, such as enzymatic reactions. For on-chip multiple reactions, we present sequential fluidic manipulations with nanoliter-sized droplets, based on the precise control of wettability and the capillary pressure of a microchannel. The microfluidic chip we have developed successfully performed biochemical reactions and can dispense a droplet of a few hundred nanoliters on the MALDI target plate according to the designed multiple reaction procedure. Finally, the MS spectrum showed accurate and clear characteristic peaks for reaction products. Our investigations into reaction efficiency showed that the microfluidic chip could reduce the reaction time to one third, and the volume to one hundredth, of off-chip methods using conventional labware such as the micropipette and Eppendorf tube.

  6. Multistep liquid-phase lithography for fast prototyping of microfluidic free-flow-electrophoresis chips.

    PubMed

    Jezierski, Stefan; Gitlin, Leonid; Nagl, Stefan; Belder, Detlev

    2011-11-01

    We present a fast and versatile method to produce functional micro free-flow electrophoresis chips. Microfluidic structures were generated between two glass slides applying multistep liquid-phase lithography, omitting troublesome bonding steps or cost-intensive master structures. Utilizing a novel spacer-less approach with the photodefinable polymer polyethyleneglycol dimethacrylate (PEG-DA), microfluidic devices with hydrophilic channels of only 25 μm in height were generated. The microfluidic chips feature ion-permeable segregation walls between the electrode channels and the separation bed and hydrophilic surfaces. The performance of the chip is demonstrated by free-flow electrophoretic separation of fluorescent xanthene dyes and fluorescently labeled amino acids.

  7. A microfluidic chip with hydrodynamic traps for in vitro microscopic investigations of single cells

    NASA Astrophysics Data System (ADS)

    Kukhtevich, I. V.; Belousov, K. I.; Bukatin, A. S.; Dubina, M. V.; Evstrapov, A. A.

    2015-03-01

    The results on making a microfluidic chip for in vitro microscopic investigations of single cells are presented. Numerical simulation of the motion trajectories of microparticles makes it possible to determine the geometry of hydrodynamic traps, their number, and the trap arrangement in a reaction chamber. According to the developed design, microfluidic chips were fabricated from a SU-8 photoresist by photolithography. The microfluidic chips have been tested to prove their operating capacity for isolating and holding K562 human myeloid leukemia cells from a sample flow and their subsequent investigation by confocal laser scanning microscopy.

  8. An integrated, multiparametric flow cytometry chip using "microfluidic drifting" based three-dimensional hydrodynamic focusing.

    PubMed

    Mao, Xiaole; Nawaz, Ahmad Ahsan; Lin, Sz-Chin Steven; Lapsley, Michael Ian; Zhao, Yanhui; McCoy, J Philip; El-Deiry, Wafik S; Huang, Tony Jun

    2012-06-01

    In this work, we demonstrate an integrated, single-layer, miniature flow cytometry device that is capable of multi-parametric particle analysis. The device integrates both particle focusing and detection components on-chip, including a "microfluidic drifting" based three-dimensional (3D) hydrodynamic focusing component and a series of optical fibers integrated into the microfluidic architecture to facilitate on-chip detection. With this design, multiple optical signals (i.e., forward scatter, side scatter, and fluorescence) from individual particles can be simultaneously detected. Experimental results indicate that the performance of our flow cytometry chip is comparable to its bulky, expensive desktop counterpart. The integration of on-chip 3D particle focusing with on-chip multi-parametric optical detection in a single-layer, mass-producible microfluidic device presents a major step towards low-cost flow cytometry chips for point-of-care clinical diagnostics.

  9. Microfluidic-Based sample chips for radioactive solutions

    DOE PAGES

    Tripp, J. L.; Law, J. D.; Smith, T. E.; ...

    2015-01-01

    Historical nuclear fuel cycle process sampling techniques required sample volumes ranging in the tens of milliliters. The radiation levels experienced by analytical personnel and equipment, in addition to the waste volumes generated from analysis of these samples, have been significant. These sample volumes also impacted accountability inventories of required analytes during process operations. To mitigate radiation dose and other issues associated with the historically larger sample volumes, a microcapillary sample chip was chosen for further investigation. The ability to obtain microliter volume samples coupled with a remote automated means of sample loading, tracking, and transporting to the analytical instrument wouldmore » greatly improve analytical efficiency while reducing both personnel exposure and radioactive waste volumes. Sample chip testing was completed to determine the accuracy, repeatability, and issues associated with the use of microfluidic sample chips used to supply µL sample volumes of lanthanide analytes dissolved in nitric acid for introduction to an analytical instrument for elemental analysis.« less

  10. Integrated circuit/microfluidic chip to programmably trap and move cells and droplets with dielectrophoresis.

    PubMed

    Hunt, Thomas P; Issadore, David; Westervelt, R M

    2008-01-01

    We present an integrated circuit/microfluidic chip that traps and moves individual living biological cells and chemical droplets along programmable paths using dielectrophoresis (DEP). Our chip combines the biocompatibility of microfluidics with the programmability and complexity of integrated circuits (ICs). The chip is capable of simultaneously and independently controlling the location of thousands of dielectric objects, such as cells and chemical droplets. The chip consists of an array of 128 x 256 pixels, 11 x 11 microm(2) in size, controlled by built-in SRAM memory; each pixel can be energized by a radio frequency (RF) voltage of up to 5 V(pp). The IC was built in a commercial foundry and the microfluidic chamber was fabricated on its top surface at Harvard. Using this hybrid chip, we have moved yeast and mammalian cells through a microfluidic chamber at speeds up to 30 microm sec(-1). Thousands of cells can be individually trapped and simultaneously positioned in controlled patterns. The chip can trap and move pL droplets of water in oil, split one droplet into two, and mix two droplets into one. Our IC/microfluidic chip provides a versatile platform to trap and move large numbers of cells and fluid droplets individually for lab-on-a-chip applications.

  11. Lab-chip HPLC with integrated droplet-based microfluidics for separation and high frequency compartmentalisation.

    PubMed

    Kim, Jin-Young; Cho, Soong-Won; Kang, Dong-Ku; Edel, Joshua B; Chang, Soo-Ik; deMello, Andrew J; O'Hare, Danny

    2012-09-21

    We demonstrate the integration of a droplet-based microfluidic device with high performance liquid chromatography (HPLC) in a monolithic format. Sequential operations of separation, compartmentalisation and concentration counter were conducted on a monolithic chip. This describes the use of droplet-based microfluidics for the preservation of chromatographic separations, and its potential application as a high frequency fraction collector.

  12. Micro-fluidic and lab-on-a-chip technology.

    PubMed

    Zhang, X; Haswell, S J

    2006-01-01

    By reducing the operational dimensions of a conventional macrofluidic-based system down to the micron scale, one can not only reduce the sample volume, but also access a range of unique characteristics, which are not achievable in conventional macro-scale systems. This chapter will discuss the unique properties of miniaturised systems based on micro-fluidic and Lab-on-a-Chip technology and consider how these may influence the overall performance associated with chemical and biological processing. Some consideration will also be given to the selection of materials and/or surface modifications that will be proactive in exploiting the high surface area and thermal and mass transfer properties, to enhance process performance.

  13. Isoelectric focusing in a poly(dimethylsiloxane) microfluidic chip.

    PubMed

    Cui, Huanchun; Horiuchi, Keisuke; Dutta, Prashanta; Ivory, Cornelius F

    2005-03-01

    This paper reports the application of ampholyte-based isoelectric focusing in poly(dimethylsiloxane) (PDMS) using methylcellulose (MC) to reduce electroosmosis and peak drift. Although the characteristics of PDMS make it possible to fabricate microfluidic chips using soft lithography, unstable electroosmotic flow (EOF) and cathodic drift are significant problems when this medium is used. This paper demonstrates that EOF is greatly reduced in PDMS by applying a dynamic coat of MC to the channel walls and that higher concentrations of MC can be used to increase the viscosity of the electrode solutions in order to suppress pH gradient drift and reduce "compression"of the pH gradient. To illustrate the effect of MC on performance, several fluorescent proteins were focused in microchip channels 5 microm deep by 300 microm wide by 2 cm long in 3-10 min using broad-range ampholytes at electric field strengths ranging from 25 to 100 V/cm.

  14. Polydimethylsiloxane-integratable micropressure sensor for microfluidic chips

    PubMed Central

    Wang, Limu; Zhang, Mengying; Yang, Min; Zhu, Weiming; Wu, Jinbo; Gong, Xiuqing; Wen, Weijia

    2009-01-01

    A novel microfluidic pressure sensor which can be fully integrated into polydimethylsiloxane (PDMS) is reported. The sensor produces electrical signals directly. We integrated PDMS-based conductive composites into a 30 μm thick membrane and bonded it to the microchannel side wall. The response time of the sensor is approximately 100 ms and can work within a pressure range as wide as 0–100 kPa. The resolution of this micropressure sensor is generally 0.1 kPa but can be increased to 0.01 kPa at high pressures as a result of the quadratic relationship between resistance and pressure. The PDMS-based nature of the sensor ensures its perfect bonding with PDMS chips, and the standard photolithographic process of the sensor allows one-time fabrication of three dimensional structures or even microsensor arrays. The theoretical calculations are in good agreement with experimental observations. PMID:20216961

  15. Fish-on-a-chip: microfluidics for zebrafish research.

    PubMed

    Yang, Fan; Gao, Chuan; Wang, Ping; Zhang, Guo-Jun; Chen, Zuanguang

    2016-04-07

    High-efficiency zebrafish (embryo) handling platforms are crucially needed to facilitate the deciphering of the increasingly expanding vertebrate-organism model values. However, the manipulation platforms for zebrafish are scarce and rely mainly on the conventional "static" microtiter plates or glass slides with rigid gel, which limits the dynamic, three-dimensional (3D), tissue/organ-oriented information acquisition from the intact larva with normal developmental dynamics. In addition, these routine platforms are not amenable to high-throughput handling of such swimming multicellular biological entities at the single-organism level and incapable of precisely controlling the growth microenvironment by delivering stimuli in a well-defined spatiotemporal fashion. Recently, microfluidics has been developed to address these technical challenges via tailor-engineered microscale structures or structured arrays, which integrate with or interface to functional components (e.g. imaging systems), allowing quantitative readouts of small objects (zebrafish larvae and embryos) under normal physiological conditions. Here, we critically review the recent progress on zebrafish manipulation, imaging and phenotype readouts of external stimuli using these microfluidic tools and discuss the challenges that confront these promising "fish-on-a-chip" technologies. We also provide an outlook on future potential trends in this field by combining with bionanoprobes and biosensors.

  16. A world-to-chip socket for microfluidic prototype development

    NASA Astrophysics Data System (ADS)

    Yang, Zhen; Maeda, Ryutaro

    2002-11-01

    This paper reports a prototype for a standard connector between a microfluidic chip and the macro world. This prototype is the first to demonstrate a fully functioning socket for a microchip to access the outside world by means of fluids, data and energy supply, as well as providing process visibility. It has 20 channels for the input and output of liquids or gases, as well as compressed air or vacuum lines for pneumatic power lines. It also contains 42 pins for electrical signals and power. All these connections were designed in a planar configuration with linear orthogonal arrays. The vertical space was opened for optical measurement and evaluation. The die (29.1 mm x 27.5 mm x 0.9 mm) can be easily mounted and dismounted from the socket. No adhesives or solders are used at any contact points. The pressure limit for the connection of working fluids was 0.2 MPa and the current limit for the electrical connections was 1 A. This socket supports both serial and parallel processing applications. It exhibits great potential for developing microfluidic system efficiently.

  17. Stem cell culture and differentiation in microfluidic devices toward organ-on-a-chip.

    PubMed

    Zhang, Jie; Wei, Xiaofeng; Zeng, Rui; Xu, Feng; Li, XiuJun

    2017-06-01

    Microfluidic lab-on-a-chip provides a new platform with unique advantages to mimic complex physiological microenvironments in vivo and has been increasingly exploited to stem cell research. In this review, we highlight recent advances of microfluidic devices for stem cell culture and differentiation toward the development of organ-on-a-chip, especially with an emphasis on vital innovations within the last 2 years. Various aspects for improving on-chip stem-cell culture and differentiation, particularly toward organ-on-a-chip, are discussed, along with microenvironment control, surface modification, extracellular scaffolds, high throughput and stimuli. The combination of microfluidic technologies and stem cells hold great potential toward versatile systems of 'organ-on-a-chip' as desired. Adapted with permission from [1-8].

  18. Studies on spectroscopy of glycerol in THz range using microfluidic chip-integrated micropump

    NASA Astrophysics Data System (ADS)

    Su, Bo; Han, Xue; Wu, Ying; Zhang, Cunlin

    2014-11-01

    Terahertz time-domain spectroscopy (THz-TDS) is a detection method of biological molecules with label-free, non-ionizing, non-intrusive, no pollution and real-time monitoring. But owing to the strong THz absorption by water, it is mainly used in the solid state detection of biological molecules. In this paper, we present a microfluidic chip technique for detecting biological liquid samples using the transmission type of THz-TDS system. The microfluidic channel of the microfluidic chip is fabricated in the quartz glass using Micro-Electro-Mechanical System (MEMS) technology and sealed with polydimethylsiloxane (PDMS) diaphragm. The length, width and depth of the microfluidic channel are 25mm, 100μm and 50μm, respectively. The diameter of THz detection zone in the microfluidic channel is 4mm. The thicknesses of quartz glass and PDMS diaphragm are 1mm and 250μm, individually. Another one of the same quartz glass is used to bond with the PDMS for the rigidity and air tightness of the microfluidic chip. In order to realize the automation of sampling and improve the control precise of fluid, a micropump, which comprises PDMS diaphragm, pump chamber, diffuser and nozzle and flat vibration motor, is integrated on the microfluidic chip. The diffuser and nozzle are fabricated on both sides of the pump chamber, which is covered with PDMS diaphragm. The flat vibration motor is stuck on the PDMS diaphragm as the actuator. We study the terahertz absorption spectroscopy characteristics of glycerol with the concentration of 98% in the microfluidic chip by the aid of the THz-TDS system, and the feasibility of the microfluidic chip for the detection of liquid samples is proved.

  19. Integration of microelectronic chips in microfluidic systems on printed circuit board

    NASA Astrophysics Data System (ADS)

    Burdallo, I.; Jimenez-Jorquera, C.; Fernández-Sánchez, C.; Baldi, A.

    2012-10-01

    A new scheme for the integration of small semiconductor transducer chips with microfluidic structures on printed circuit board (PCB) is presented. The proposed approach is based on a packaging technique that yields a large and flat area with small and shallow (˜44 µm deep) openings over the chips. The photocurable encapsulant material used, based on a diacrylate bisphenol A polymer, enables irreversible bonding of polydimethylsiloxane microfluidic structures at moderate temperatures (80 °C). This integration scheme enables the insertion of transducer chips in microfluidic systems with a lower added volume than previous schemes. Leakage tests have shown that the bonded structures withstand more than 360 kPa of pressure. A prototype microfluidic system with two detection chips, including one inter-digitated electrode (IDE) chip for conductivity and one ion selective field effect transistor (ISFET) chip for pH, has been implemented and characterized. Good electrical insulation of the chip contacts and silicon edge surfaces from the solution in the microchannels has been achieved. This integration procedure opens the door to the low-cost fabrication of complex analytical microsystems that combine the extraordinary potential of both the microfluidics and silicon microtechnology fields.

  20. PPC750 Performance Monitor

    NASA Technical Reports Server (NTRS)

    Meyer, Donald; Uchenik, Igor

    2007-01-01

    The PPC750 Performance Monitor (Perfmon) is a computer program that helps the user to assess the performance characteristics of application programs running under the Wind River VxWorks real-time operating system on a PPC750 computer. Perfmon generates a user-friendly interface and collects performance data by use of performance registers provided by the PPC750 architecture. It processes and presents run-time statistics on a per-task basis over a repeating time interval (typically, several seconds or minutes) specified by the user. When the Perfmon software module is loaded with the user s software modules, it is available for use through Perfmon commands, without any modification of the user s code and at negligible performance penalty. Per-task run-time performance data made available by Perfmon include percentage time, number of instructions executed per unit time, dispatch ratio, stack high water mark, and level-1 instruction and data cache miss rates. The performance data are written to a file specified by the user or to the serial port of the computer

  1. Automatic particle detection and sorting in an electrokinetic microfluidic chip.

    PubMed

    Song, Yongxin; Peng, Ran; Wang, Junsheng; Pan, Xinxiang; Sun, Yeqing; Li, Dongqing

    2013-03-01

    This paper reports a lab-on-a-chip device that can automatically detect and sort particles based on their size differences with a high resolution. The PDMS-glass microfluidic chip is made by soft-lithography technique. A differential resistive pulse sensor is employed to electrically detect the sizes of the particles in EOF generated by applying DC voltages across channels. The detected resistive pulse sensor signals, whose amplitudes are proportional to particles' sizes, will automatically trigger the sorting process that is controlled by applying a voltage pulse (36 V) whenever a target particle is detected. This method was applied to automatically detect and sort polystyrene particles and microalgae in aqueous solutions. Sorting 5 μm polymer particle from a mixture of 4- and 5-μm polystyrene particles in aqueous solution, i.e. 1 μm sorting resolution, was demonstrated. The device described in this paper is simple, automatic, and label-free with high sorting resolution. It has wide applications in sample pretreatment and target particles detection. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. A Rapidly Fabricated Microfluidic Chip for Cell Culture.

    PubMed

    Li, Rui; Lv, Xuefei; Hasan, Murtaza; Xu, Jiandong; Xu, Yuanqing; Zhang, Xingjian; Qin, Kuiwei; Wang, Jianshe; Zhou, Di; Deng, Yulin

    2016-04-01

    Microfluidic chips (μFC) are emerging as powerful tools in chemistry, biochemistry, nanotechnology and biotechnology. The microscale size, possibility of integration and high-throughput present huge technical potential to facilitate the research of cell behavior by creating in vivo-like microenvironments. Here, we have developed a new method for rapid fabrication of μFC with Norland Optical Adhesive 81 (NOA81) for multiple cell culture with high efficiency. The proposed method is more suitable for the early structure exploration stage of μFC than existing procedures since no templates are needed and fast fabrication methods are presented. Simple PDMS-NOA81-linked microvalves were embedded in the μFC to control or block the fluid flow effectively, which significantly broadened the applications of μFC. Various types of cells were integrated into the chip and normal viabilities were maintained up to 1 week. Besides, concentration gradient was generated to investigate the cells in the μFC responded to drug stimulation. The cells appeared different in terms of shape and proliferation that strongly demonstrated the potential application of our μFC in online drug delivery. The high biocompatibility of NOA81 and its facile fabrication (μFC) promise its use in various cell analyses, such as cell-cell interactions or tissue engineering.

  3. Terahertz microfluidic chips for detection of amino acids in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Su, Bo; Zhang, Cong; Fan, Ning; Zhang, Cunlin

    2016-11-01

    Microfluidic technology can control the fluidic thickness accurately in less than 100 micrometers. So the combination of terahertz (THz) and microfluidic technology becomes one of the most interesting directions towards biological detection. We designed microfluidic chips for terahertz spectroscopy of biological samples in aqueous solutions. Using the terahertz time-domain spectroscopy (THz-TDS) system, we experimentally measured the transmittance of the chips and the THz absorption spectra of L-threonine and L-arginine, respectively. The results indicated the feasibility of performing high sensitivity THz spectroscopy of amino acids solutions. Therefore, the microfluidic chips can realize real-time and label-free measurement for biochemistry samples in THz-TDS system.

  4. In situ ZnO-PVA nanocomposite coated microfluidic chips for biosensing

    NASA Astrophysics Data System (ADS)

    Habouti, Salah; Kunstmann-Olsen, Casper; Hoyland, James D.; Rubahn, Horst-Günter; Es-Souni, Mohammed

    2014-05-01

    Microfluidic chips with integrated fluid and optical connectors have been generated via a simple PDMS master-mould technique. In situ coating using a Zinc oxide polyvinylalcohol based sol-gel method results in ultrathin nanocomposite layers on the fluid channels, which makes them strongly hydrophilic and minimizes auto contamination of the chips by injected fluorescent biomarkers.

  5. PDMS based microfluidic chips and their application in material synthesis

    NASA Astrophysics Data System (ADS)

    Gong, Xiuqing

    reactions. Here, we report the microfluidic fabrication of magnetically responsive microsphere, macroporous polymer microspheres and hollow titania microspheres. To prepare magnetically responsive microsphere, we introduced magnetic particles into liquid shell and drug into liquid core. After cross-linking reaction of the shell, we studied the magnetic contraction and extention behavior which induced the drug release efficiency. To prepare porous polymer, the H 2O2 solution was encapsulated in polymer precursor, after which we investigated its decomposition under UV irradiation, which simultaneously induces the polymerization of the encapsulating shell. Because the H 2O2 decomposition leads to the release of oxygen, porous microspheres were obtained from a combined H2O2-decomposition/polymer precursor polymerization reaction. To prepare hollow titanium gel microspheres, water droplets were first formed by the flow focusing geometry in microfluidic chip and used as a soft template. Then hydrolysis and gelation of titanium alkoxide on the droplet's surface were induced in following serpentine channels, controlled by interface water diffusion. The water diffusion process can be controlled by the amount of the "dewetting" reagent butanol, by which the surface morphology of the titania microspheres can be tuned.

  6. Microfluidic chips for the study of cell migration under the effect of chemicals

    NASA Astrophysics Data System (ADS)

    Kukhtevich, I. V.; Belousov, K. I.; Bukatin, A. S.; Chubinskiy-Nadezhdin, V. I.; Vasileva, V. Yu.; Negulyaev, Yu. A.; Evstrapov, A. A.

    2016-05-01

    Numerical simulation of the formation of a chemoattractant gradient in reaction chambers of a chip having different geometries enabled the determination of a structure suitable for the study of cell migration, in accordance with which hybrid polymer-glass microfluidic devices were manufactured. Verification of the procedures of alignment of cells in the reaction chamber of the chip by centrifugal force and subsequent culturing of the cells showed that microfluidic chips can be used to study cell migration under the effect of the chemoattractant gradient in vitro.

  7. Cooperative suction by vertical capillary array pump for controlling flow profiles of microfluidic sensor chips.

    PubMed

    Horiuchi, Tsutomu; Hayashi, Katsuyoshi; Seyama, Michiko; Inoue, Suzuyo; Tamechika, Emi

    2012-10-18

    A passive pump consisting of integrated vertical capillaries has been developed for a microfluidic chip as an useful component with an excellent flow volume and flow rate. A fluidic chip built into a passive pump was used by connecting the bottoms of all the capillaries to a top surface consisting of a thin layer channel in the microfluidic chip where the thin layer channel depth was smaller than the capillary radius. As a result the vertical capillaries drew fluid cooperatively rather than independently, thus exerting the maximum suction efficiency at every instance. This meant that a flow rate was realized that exhibited little variation and without any external power or operation. A microfluidic chip built into this passive pump had the ability to achieve a quasi-steady rather than a rapidly decreasing flow rate, which is a universal flow characteristic in an ordinary capillary.

  8. Stem cell culture and differentiation in microfluidic devices toward organ-on-a-chip

    PubMed Central

    Zhang, Jie; Wei, Xiaofeng; Zeng, Rui; Xu, Feng; Li, XiuJun

    2017-01-01

    Microfluidic lab-on-a-chip provides a new platform with unique advantages to mimic complex physiological microenvironments in vivo and has been increasingly exploited to stem cell research. In this review, we highlight recent advances of microfluidic devices for stem cell culture and differentiation toward the development of organ-on-a-chip, especially with an emphasis on vital innovations within the last 2 years. Various aspects for improving on-chip stem-cell culture and differentiation, particularly toward organ-on-a-chip, are discussed, along with microenvironment control, surface modification, extracellular scaffolds, high throughput and stimuli. The combination of microfluidic technologies and stem cells hold great potential toward versatile systems of ‘organ-on-a-chip’ as desired. Adapted with permission from [1–8]. PMID:28670476

  9. Cooperative Suction by Vertical Capillary Array Pump for Controlling Flow Profiles of Microfluidic Sensor Chips

    PubMed Central

    Horiuchi, Tsutomu; Hayashi, Katsuyoshi; Seyama, Michiko; Inoue, Suzuyo; Tamechika, Emi

    2012-01-01

    A passive pump consisting of integrated vertical capillaries has been developed for a microfluidic chip as an useful component with an excellent flow volume and flow rate. A fluidic chip built into a passive pump was used by connecting the bottoms of all the capillaries to a top surface consisting of a thin layer channel in the microfluidic chip where the thin layer channel depth was smaller than the capillary radius. As a result the vertical capillaries drew fluid cooperatively rather than independently, thus exerting the maximum suction efficiency at every instance. This meant that a flow rate was realized that exhibited little variation and without any external power or operation. A microfluidic chip built into this passive pump had the ability to achieve a quasi-steady rather than a rapidly decreasing flow rate, which is a universal flow characteristic in an ordinary capillary. PMID:23202035

  10. Re-use of commercial microfluidics chips for DNA, RNA, and protein electrophoresis.

    PubMed

    Nguyen, Thi; Kwak, Sukyoung; Karpowicz, Steven J

    2014-11-01

    Microfluidics chip technology is a powerful and convenient alternative to agarose gels and PAGE, but costs can be high due to certain chips being non-reusable. Here we describe a method to regenerate, re-use, and store Agilent DNA, RNA, and protein electrophoresis chips designed for use in the Bioanalyzer 2100. By washing the sample wells and displacing the old gel matrix with new gel-dye mix, we have run samples on the same chip up to ten times with negligible loss of signal quality. Chips whose wells were loaded with buffer or water were stored successfully for one week before re-use.

  11. A chemically inert multichannel chip-to-world interface to connect microfluidic chips

    NASA Astrophysics Data System (ADS)

    Neumann, Christiane; Wilhelm, Elisabeth; Duttenhofer, Thomas; Pires, Leonardo; Rapp, Bastian E.

    2014-03-01

    Within the last decades more and more microfluidic systems for applications in chemistry, biology or medicine were developed. Most of them need a connection between the chip and its macroscopic environment e.g., pumps. Numerous concepts for such interconnections are known from literature but most of them allow only a small number of connections and are neither chemically inert nor contamination-free. We developed a chemically inert, reusable, multichannel Chipto- World-Interface (CWI) based on a force fit connection. This principle is comparable to hollow screws as used in highperformance liquid chromatography. The CWI can be used to connect chips, made of different materials, e.g., glass, polydimethylsiloxane (PDMS), or epoxy polymers, with up to 100 thermoplastic tubes. The dimensions of the CWI and the number of connections can be individually adapted depending on the chip dimensions but the pitch between the tubes is fixed. Due to the design of the CWI the fluid is only in contact with the chip and the tubing material, thus leading to a contamination free and zero dead volume interconnection. Using tubes of polytetrafluorethylene (PTFE, Teflon®) even enables probing with organic solvents like dimethylformamide, dichloromethane or tetrahydrofuran over several hours without leakage or corrosion of the CWI. During experiments the CWI with 100 connections resisted pressure up to 630 kPa (6.3 bar) and sustained flow rates higher than 4 ml/min.

  12. Microfluidic cytometers with integrated on-chip optical components for blood cell analysis

    NASA Astrophysics Data System (ADS)

    Zhao, Yingying; Li, Qin; Hu, Xiao-Ming

    2016-10-01

    In the last two decades, microfluidic technologies have shown the great potential in developing portable and point-of care testing blood cell analysis devices. It is challenging to integrate all free-space detecting components in a single microfluidic platform. In this paper, a microfluidic cytometer with integrated on-chip optical components was demonstrated. To facilitate on-chip detection, the device integrated optical fibers and on-chip microlens with microfluidic channels on one polydimethylsiloxane layer by standard soft photolithography. This compact design increased the sensitivity of the device and also eliminated time-consuming free-space optical alignments. Polystyrene particles, together with red blood cells and platelets, were measured in the microfluidic cytometer by small angle forward scatter. Experimental results indicated that the performance of the microfluidic device was comparable to a conventional cytometer. And it was also demonstrated its ability to detect on-chip optical signals in a highly compact, simple, truly portable and low cost format which was perfect suitable for point-of-care testing clinical hematology diagnostics.

  13. Microfluidic lab-on-a-chip platforms: requirements, characteristics and applications.

    PubMed

    Mark, Daniel; Haeberle, Stefan; Roth, Günter; von Stetten, Felix; Zengerle, Roland

    2010-03-01

    This critical review summarizes developments in microfluidic platforms that enable the miniaturization, integration, automation and parallelization of (bio-)chemical assays (see S. Haeberle and R. Zengerle, Lab Chip, 2007, 7, 1094-1110, for an earlier review). In contrast to isolated application-specific solutions, a microfluidic platform provides a set of fluidic unit operations, which are designed for easy combination within a well-defined fabrication technology. This allows the easy, fast, and cost-efficient implementation of different application-specific (bio-)chemical processes. In our review we focus on recent developments from the last decade (2000s). We start with a brief introduction into technical advances, major market segments and promising applications. We continue with a detailed characterization of different microfluidic platforms, comprising a short definition, the functional principle, microfluidic unit operations, application examples as well as strengths and limitations of every platform. The microfluidic platforms in focus are lateral flow tests, linear actuated devices, pressure driven laminar flow, microfluidic large scale integration, segmented flow microfluidics, centrifugal microfluidics, electrokinetics, electrowetting, surface acoustic waves, and dedicated systems for massively parallel analysis. This review concludes with the attempt to provide a selection scheme for microfluidic platforms which is based on their characteristics according to key requirements of different applications and market segments. Applied selection criteria comprise portability, costs of instrument and disposability, sample throughput, number of parameters per sample, reagent consumption, precision, diversity of microfluidic unit operations and the flexibility in programming different liquid handling protocols (295 references).

  14. Fabrication of 25 μm-filter microfluidic chip on silicon substrate

    NASA Astrophysics Data System (ADS)

    Ngan Le, Nguyen; Khanh Huynh, Kim; Cam Hue Phan, Thi; Dung Dang, Thi My; Chien Dang, Mau

    2017-03-01

    This paper presents the entire fabrication process including photolithography, sputtering, deep reactive ion etching (Bosch DRIE process) on silicon substrate and bonding process between the lid and silicon substrate to create a designed filtration microfluidic chip with dimension of 28 mm × 7 mm, one inlet port and one outlet port. A pattered silver thin film was deposited on a silicon sample by the lift-off method. Subsequently the newly fabricated sample was anisotropically etched by Bosch DRIE process. Some parameters of Bosch DRIE process such as bias power, duration of etching step and passivation step, oxygen presence were studied to explore the dependence of silicon channel depth and etched shape profile on these parameters. An optimized process was utilized to fabricate a featured silicon channel with vertical, smooth sidewalls and an overall good uniformity. The silicon channel has four arrays of microposts with various distances between microposts from 25 μm to 100 μm. The depth of the silicon channel was about 150 μm. After that, silicon substrate was bonded with mica lid by adhesive bonding method to form the completed filtration microfluidic chip. The samples were characterized by scanning electron microscopy (SEM), mechanical profilometer (DEKTAK 6 M), optical microscopy (Olympus MX51). In this paper a test was performed to demonstrate how the microfluidic chip works by pumping solution with many various sizes of particles through the inlet port of the microfluidic chip and obtaining a solution with desired particles sizes (smaller than 25 μm) through another port. Moreover, the chip could be pumped de-ionized water through outlet port for backwash in order to make this microfluidic chip reusable. Finally, a few applications of microfluidic chips are presented to illustrate the advantages of this technology and the potential for future development. Invited talk at 8th International Workshop on Advanced Materials Science and Nanotechnology

  15. On-chip microfluidic biosensor using superparamagnetic microparticles

    PubMed Central

    Kokkinis, G.; Keplinger, F.; Giouroudi, I.

    2013-01-01

    In this paper, an integrated solution towards an on-chip microfluidic biosensor using the magnetically induced motion of functionalized superparamagnetic microparticles (SMPs) is presented. The concept of the proposed method is that the induced velocity on SMPs in suspension, while imposed to a magnetic field gradient, is inversely proportional to their volume. Specifically, a velocity variation of suspended functionalized SMPs inside a detection microchannel with respect to a reference velocity, specified in a parallel reference microchannel, indicates an increase in their non-magnetic volume. This volumetric increase of the SMPs is caused by the binding of organic compounds (e.g., biomolecules) to their functionalized surface. The new compounds with the increased non-magnetic volume are called loaded SMPs (LSMPs). The magnetic force required for the manipulation of the SMPs and LSMPs is produced by current currying conducting microstructures, driven by a programmable microcontroller. Experiments were carried out as a proof of concept. A promising decrease in the velocity of the LSMPs in comparison to that of the SMPs was measured. Thus, it is the velocity variation which determines the presence of the organic compounds in the sample fluid. PMID:24396528

  16. Microfluidic on-chip fluorescence-activated interface control system.

    PubMed

    Haiwang, Li; Nguyen, N T; Wong, T N; Ng, S L

    2010-11-22

    A microfluidic dynamic fluorescence-activated interface control system was developed for lab-on-a-chip applications. The system consists of a straight rectangular microchannel, a fluorescence excitation source, a detection sensor, a signal conversion circuit, and a high-voltage feedback system. Aqueous NaCl as conducting fluid and aqueous glycerol as nonconducting fluid were introduced to flow side by side into the straight rectangular microchannel. Fluorescent dye was added to the aqueous NaCl to work as a signal representing the interface position. Automatic control of the liquid interface was achieved by controlling the electroosmotic effect that exists only in the conducting fluid using a high-voltage feedback system. A LABVIEW program was developed to control the output of high-voltage power supply according the actual interface position, and then the interface position is modified as the output of high-voltage power supply. At last, the interface can be moved to the desired position automatically using this feedback system. The results show that the system presented in this paper can control an arbitrary interface location in real time. The effects of viscosity ratio, flow rates, and polarity of electric field were discussed. This technique can be extended to switch the sample flow and droplets automatically.

  17. Rapid prototyping of microfluidic chips for dead-volume-free MS coupling.

    PubMed

    Dietze, Claudia; Scholl, Tobias; Ohla, Stefan; Appun, Johannes; Schneider, Christoph; Belder, Detlev

    2015-11-01

    A fast and straightforward method to prototype microfluidic chip systems for dead-volume-free hyphenation to electrospray-ionisation mass spectrometry is presented. The developed approach based on liquid-phase lithography provides an inexpensive and reliable access to microfluidic chips for MS coupling which can be manufactured in any laboratory with low technical demands. The rapid prototyping approach enables the seamless integration of capillaries serving as electrospray emitters with negligible dead volume. The high versatility of the presented prototyping method and the applicability of a variety of chip-based devices in different fields of lab-on-a-chip technology are established for analytical separations by means of chip-electrochromatography-MS and for continuous-flow synthesis using microreactor technology with MS detection.

  18. Direct optical patterning of poly(dimethylsiloxane) microstructures for microfluidic chips

    NASA Astrophysics Data System (ADS)

    Gao, Shaorui; Tung, Wing-Tai; Wong, Dexter S.; Bian, Liming; Zhang, A. Ping

    2016-10-01

    In this paper, we present an optical maskless exposure approach for direct patterning of large-area high resolution microfluidic chips using photosensitive poly(dimethylsiloxane) (PDMS) materials. Both positive- and negative-tone photosensitive PDMS (photoPDMS) were successfully patterned into various microfluidic devices with complex geometries by using an optical maskless lithography process. The positive-tone PDMS is used for patterning of largearea chips, while the negative-tone PDMS is demonstrated to fabricate high-resolution microstructures and on-chip devices. With the seamless pattern-stitching technique, a large-area microfluidic chip with size of 5.5 × 2.8 cm2 with complex three-dimensional (3D) staggered herringbone mixers (SHMs) for micro-flow gradient generation has been directly fabricated within 125 minutes by using the positive-tone PDMS. A small microfluidic chip with feature size as small as 5 μm is demonstrated by using the negative-tone PDMS. The experimental results reveal that the optical maskless lithography technology enables to rapidly pattern high-resolution microstructures and is very promising for development of lab-on-a-chip devices.

  19. Rapid fabrication of a four-layer PMMA-based microfluidic chip using CO2-laser micromachining and thermal bonding

    NASA Astrophysics Data System (ADS)

    Chen, Xueye; Shen, Jienan; Zhou, Mengde

    2016-10-01

    A smart design method to transform the original two-layer microfluidic chip into a four-layer 3D microfluidic chip is proposed. A novel fabrication method is established to rapidly and effectively produce a four-layer microfluidic chip device made entirely from polymethylmethacrylate (PMMA). Firstly, the CO2-laser cuts the PMMA sheets by melting and blowing away vaporized material from the parent material to obtain high-quality channels of the microfluidic chip. An orthogonal experimental method is used to study its processing stability. In addition, a simple, rapid thermal bonding technique is successfully applied in fabricating the four-layer microfluidic chip, which has a bond strength of 1.3 MPa. A wooden pole is used to improve the accuracy of the alignment. Finally, a mixing experiment with blue ink and water is carried out, which proves that this smart design method and rapid manufacturing technology are successful.

  20. Thin film metal sensors in fusion bonded glass chips for high-pressure microfluidics

    NASA Astrophysics Data System (ADS)

    Andersson, Martin; Ek, Johan; Hedman, Ludvig; Johansson, Fredrik; Sehlstedt, Viktor; Stocklassa, Jesper; Snögren, Pär; Pettersson, Victor; Larsson, Jonas; Vizuete, Olivier; Hjort, Klas; Klintberg, Lena

    2017-01-01

    High-pressure microfluidics offers fast analyses of thermodynamic parameters for compressed process solvents. However, microfluidic platforms handling highly compressible supercritical CO2 are difficult to control, and on-chip sensing would offer added control of the devices. Therefore, there is a need to integrate sensors into highly pressure tolerant glass chips. In this paper, thin film Pt sensors were embedded in shallow etched trenches in a glass wafer that was bonded with another glass wafer having microfluidic channels. The devices having sensors integrated into the flow channels sustained pressures up to 220 bar, typical for the operation of supercritical CO2. No leakage from the devices could be found. Integrated temperature sensors were capable of measuring local decompression cooling effects and integrated calorimetric sensors measured flow velocities over the range 0.5-13.8 mm s-1. By this, a better control of high-pressure microfluidic platforms has been achieved.

  1. IFSA: a microfluidic chip-platform for frit-based immunoassay protocols

    NASA Astrophysics Data System (ADS)

    Hlawatsch, Nadine; Bangert, Michael; Miethe, Peter; Becker, Holger; Gärtner, Claudia

    2013-03-01

    Point-of-care diagnostics (POC) is one of the key application fields for lab-on-a-chip devices. While in recent years much of the work has concentrated on integrating complex molecular diagnostic assays onto a microfluidic device, there is a need to also put comparatively simple immunoassay-type protocols on a microfluidic platform. In this paper, we present the development of a microfluidic cartridge using an immunofiltration approach. In this method, the sandwich immunoassay takes place in a porous frit on which the antibodies have immobilized. The device is designed to be able to handle three samples in parallel and up to four analytical targets per sample. In order to meet the critical cost targets for the diagnostic market, the microfluidic chip has been designed and manufactured using high-volume manufacturing technologies in mind. Validation experiments show comparable sensitivities in comparison with conventional immunofiltration kits.

  2. Development of a Plastic-Based Microfluidic Immunosensor Chip for Detection of H1N1 Influenza

    PubMed Central

    Lee, Kyoung G.; Lee, Tae Jae; Jeong, Soon Woo; Choi, Ho Woon; Heo, Nam Su; Park, Jung Youn; Park, Tae Jung; Lee, Seok Jae

    2012-01-01

    Lab-on-a-chip can provide convenient and accurate diagnosis tools. In this paper, a plastic-based microfluidic immunosensor chip for the diagnosis of swine flu (H1N1) was developed by immobilizing hemagglutinin antigen on a gold surface using a genetically engineered polypeptide. A fluorescent dye-labeled antibody (Ab) was used for quantifying the concentration of Ab in the immunosensor chip using a fluorescent technique. For increasing the detection efficiency and reducing the errors, three chambers and three microchannels were designed in one microfluidic chip. This protocol could be applied to the diagnosis of other infectious diseases in a microfluidic device. PMID:23112630

  3. Rapid fabrication of microfluidic chips based on the simplest LED lithography

    NASA Astrophysics Data System (ADS)

    Li, Yue; Wu, Ping; Luo, Zhaofeng; Ren, Yuxuan; Liao, Meixiang; Feng, Lili; Li, Yuting; He, Liqun

    2015-05-01

    Microfluidic chips are generally fabricated by a soft lithography method employing commercial lithography equipment. These heavy machines require a critical room environment and high lamp power, and the cost remains too high for most normal laboratories. Here we present a novel microfluidics fabrication method utilizing a portable ultraviolet (UV) LED as an alternative UV source for photolithography. With this approach, we can repeat several common microchannels as do these conventional commercial exposure machines, and both the verticality of the channel sidewall and lithography resolution are proved to be acceptable. Further microfluidics applications such as mixing, blood typing and microdroplet generation are implemented to validate the practicability of the chips. This simple but innovative method decreases the cost and requirement of chip fabrication dramatically and may be more popular with ordinary laboratories.

  4. Formation Characteristics of microbubble in a co-flowing liquid in microfluidic chip

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Qin, Hongwei; Jiang, Shengyuan; Li, Peng; Sun, Lixia; Ren, Yukun

    2017-08-01

    Microbubble formation under the surroundings of co-flowing liquid (CFL) in a specially designed microfluidic chip was investigated. A new microfluidic chip utilizing several capillary tubes was fabricated to provide the co-axial flowing conditions. An experiment platform based on high-speed microscopic camera system (HSMCS) was designed and set up. The influences of nitrogen pressure and liquid flow rate on detachment distance and volume variation of target microbubble were studied experimentally. Experimental data and analysis results indicated that the detachment distance of target microbubble decreases substantially as the rate of CFL increases while it is almost independent of nitrogen pressure. Additionally, the volume growth rate of target microbubble almost keeps constant under fixed nitrogen pressure. The present study provides empirical references for studies in microbubble formation in microfluidic chips which contributes to realize the accurate controllability in diameter and size distribution of microbubble.

  5. Integration of Curved D-Type Optical Fiber Sensor with Microfluidic Chip

    PubMed Central

    Sun, Yung-Shin; Li, Chang-Jyun; Hsu, Jin-Cherng

    2016-01-01

    A curved D-type optical fiber sensor (OFS) combined with a microfluidic chip is proposed. This OFS, based on surface plasmon resonance (SPR) of the Kretchmann’s configuration, is applied as a biosensor to measure the concentrations of different bio-liquids such as ethanol, methanol, and glucose solutions. The SPR phenomenon is attained by using the optical fiber to guide the light source to reach the side-polished, gold-coated region. Integrating this OFS with a polymethylmethacrylate (PMMA)-based microfluidic chip, the SPR spectra for liquids with different refractive indices are recorded. Experimentally, the sensitivity of the current biosensor was calculated to be in the order of 10−5 RIU. This microfluidic chip-integrated OFS could be valuable for monitoring subtle changes in biological samples such as blood sugar, allergen, and biomolecular interactions. PMID:28042821

  6. 3D-printed microfluidic chips with patterned, cell-laden hydrogel constructs.

    PubMed

    Knowlton, Stephanie; Yu, Chu Hsiang; Ersoy, Fulya; Emadi, Sharareh; Khademhosseini, Ali; Tasoglu, Savas

    2016-06-20

    Three-dimensional (3D) printing offers potential to fabricate high-throughput and low-cost fabrication of microfluidic devices as a promising alternative to traditional techniques which enables efficient design iterations in the development stage. In this study, we demonstrate a single-step fabrication of a 3D transparent microfluidic chip using two alternative techniques: a stereolithography-based desktop 3D printer and a two-step fabrication using an industrial 3D printer based on polyjet technology. This method, compared to conventional fabrication using relatively expensive materials and labor-intensive processes, presents a low-cost, rapid prototyping technique to print functional 3D microfluidic chips. We enhance the capabilities of 3D-printed microfluidic devices by coupling 3D cell encapsulation and spatial patterning within photocrosslinkable gelatin methacryloyl (GelMA). The platform presented here serves as a 3D culture environment for long-term cell culture and growth. Furthermore, we have demonstrated the ability to print complex 3D microfluidic channels to create predictable and controllable fluid flow regimes. Here, we demonstrate the novel use of 3D-printed microfluidic chips as controllable 3D cell culture environments, advancing the applicability of 3D printing to engineering physiological systems for future applications in bioengineering.

  7. Active pneumatic control of centrifugal microfluidic flows for lab-on-a-chip applications.

    PubMed

    Clime, Liviu; Brassard, Daniel; Geissler, Matthias; Veres, Teodor

    2015-06-07

    This paper reports a novel method of controlling liquid motion on a centrifugal microfluidic platform based on the integration of a regulated pressure pump and a programmable electromechanical valving system. We demonstrate accurate control over the displacement of liquids within the system by pressurizing simultaneously multiple ports of the microfluidic device while the platform is rotating at high speed. Compared to classical centrifugal microfluidic platforms where liquids are solely driven by centrifugal and capillary forces, the method presented herein adds a new degree of freedom for fluidic manipulation, which represents a paradigm change in centrifugal microfluidics. We first demonstrate how various core microfluidic functions such as valving, switching, and reverse pumping (i.e., against the centrifugal field) can be easily achieved by programming the pressures applied at dedicated access ports of the microfluidic device. We then show, for the first time, that the combination of centrifugal force and active pneumatic pumping offers the possibility of mixing fluids rapidly (~0.1 s) and efficiently based on the creation of air bubbles at the bottom of a microfluidic reservoir. Finally, the suitability of the developed platform for performing complex bioanalytical assays in an automated fashion is demonstrated in a DNA harvesting experiment where recovery rates of about 70% were systematically achieved. The proposed concept offers the interesting prospect to decouple basic microfluidic functions from specific material properties, channel dimensions and fabrication tolerances, surface treatments, or on-chip active components, thus promoting integration of complex assays on simple and low-cost microfluidic cartridges.

  8. Microfluidic-integrated laser-controlled microactuators with on-chip microscopy imaging functionality

    PubMed Central

    Jung, Jae Hee; Han, Chao; Lee, Seung Ah; Kim, Jinho; Yang, Changhuei

    2014-01-01

    The fabrication of a novel microfluidic system, integrated with a set of laser-controlled microactuators on an ePetri on-chip microscopy platform, is presented in this paper. In the fully integrated microfluidic system, a set of novel thermally actuated paraffin-based microactuators, precisely controlled by programmed laser optics, was developed to regulate flow and to provide pumping of liquid solutions without external connections. The microfluidic chip was fabricated on a complementary metal–oxide–semiconductor (CMOS)-imaging sensor chip on an ePetri platform; this configuration provided real-time, wide field-of-view, high-resolution imaging using a sub-pixel sweeping microscopy technique. The system of microactuators, which consisted of microvalves and a micropump, operated well in the microfluidic channel with a focused near-infrared laser beam providing the actuation control. As a demonstration, we used our prototype to assess cell–drug interactions, and monitored cell growth directly within an incubator in real time. The powerful combination of the laser-actuated microfluidics and chip-scale microscopy techniques represents a significant step forward in terms of a simple, robust, high-throughput, and highly compact analysis system for biomedical and bioscience applications. PMID:25099225

  9. Plug-and-play, infrared, laser-mediated PCR in a microfluidic chip.

    PubMed

    Pak, Nikita; Saunders, D Curtis; Phaneuf, Christopher R; Forest, Craig R

    2012-04-01

    Microfluidic polymerase chain reaction (PCR) systems have set milestones for small volume (100 nL-5 μL), amplification speed (100-400 s), and on-chip integration of upstream and downstream sample handling including purification and electrophoretic separation functionality. In practice, the microfluidic chips in these systems require either insertion of thermocouples or calibration prior to every amplification. These factors can offset the speed advantages of microfluidic PCR and have likely hindered commercialization. We present an infrared, laser-mediated, PCR system that features a single calibration, accurate and repeatable precision alignment, and systematic thermal modeling and management for reproducible, open-loop control of PCR in 1 μL chambers of a polymer microfluidic chip. Total cycle time is less than 12 min: 1 min to fill and seal, 10 min to amplify, and 1 min to recover the sample. We describe the design, basis for its operation, and the precision engineering in the system and microfluidic chip. From a single calibration, we demonstrate PCR amplification of a 500 bp amplicon from λ-phage DNA in multiple consecutive trials on the same instrument as well as multiple identical instruments. This simple, relatively low-cost plug-and-play design is thus accessible to persons who may not be skilled in assembly and engineering.

  10. Time-of-Flight Flow Imaging of Two-Component Flow inside a Microfluidic Chip

    NASA Astrophysics Data System (ADS)

    Harel, Elad; Hilty, Christian; Koen, Katherine; McDonnell, Erin E.; Pines, Alex

    2007-01-01

    Here we report on using NMR imaging and spectroscopy in conjunction with time-of-flight tracking to noninvasively tag and monitor nuclear spins as they flow through the channels of a microfluidic chip. Any species with resolvable chemical-shift signatures can be separately monitored in a single experiment, irrespective of the optical properties of the fluids, thereby eliminating the need for foreign tracers. This is demonstrated on a chip with a mixing geometry in which two fluids converge from separate channels, and is generally applicable to any microfluidic device through which fluid flows within the nuclear spin-lattice relaxation time.

  11. Multichannel microfluidic chip for rapid and reliable trapping and imaging plant-parasitic nematodes

    NASA Astrophysics Data System (ADS)

    Amrit, Ratthasart; Sripumkhai, Witsaroot; Porntheeraphat, Supanit; Jeamsaksiri, Wutthinan; Tangchitsomkid, Nuchanart; Sutapun, Boonsong

    2013-05-01

    Faster and reliable testing technique to count and identify nematode species resided in plant roots is therefore essential for export control and certification. This work proposes utilizing a multichannel microfluidic chip with an integrated flow-through microfilter to retain the nematodes in a trapping chamber. When trapped, it is rather simple and convenient to capture images of the nematodes and later identify their species by a trained technician. Multiple samples can be tested in parallel using the proposed microfluidic chip therefore increasing number of samples tested per day.

  12. Chip-olate’ and dry-film resists for efficient fabrication, singulation and sealing of microfluidic chips

    NASA Astrophysics Data System (ADS)

    Temiz, Yuksel; Delamarche, Emmanuel

    2014-09-01

    This paper describes a technique for high-throughput fabrication and efficient singulation of chips having closed microfluidic structures and takes advantage of dry-film resists (DFRs) for efficient sealing of capillary systems. The technique is illustrated using 4-inch Si/SiO2 wafers. Wafers carrying open microfluidic structures are partially diced to about half of their thickness. Treatments such as surface cleaning are done at wafer-level, then the structures are sealed using low-temperature (45 °C) lamination of a DFR that is pre-patterned using a craft cutter, and ready-to-use chips are finally separated manually like a chocolate bar by applying a small force (≤ 4 N). We further show that some DFRs have low auto-fluorescence at wavelengths typically used for common fluorescent dyes and that mechanical properties of some DFRs allow for the lamination of 200 μm wide microfluidic structures with negligible sagging (~1 μm). The hydrophilicity (advancing contact angle of ~60°) of the DFR supports autonomous capillary-driven flow without the need for additional surface treatment of the microfluidic chips. Flow rates from 1 to 5 µL min-1 are generated using different geometries of channels and capillary pumps. In addition, the ‘chip-olate’ technique is compatible with the patterning of capture antibodies on DFR for use in immunoassays. We believe this technique to be applicable to the fabrication of a wide range of microfluidic and lab-on-a-chip devices and to offer a viable alternative to many labor-intensive processes that are currently based on wafer bonding techniques or on the molding of poly(dimethylsiloxane) (PDMS) layers.

  13. X-ray Transparent Microfluidic Chip for Mesophase-Based Crystallization of Membrane Proteins and On-Chip Structure Determination

    SciTech Connect

    Khvostichenko, Daria S.; Schieferstein, Jeremy M.; Pawate, Ashtamurthy S.; Laible, Philip D.; Kenis, Paul J. A.

    2014-10-01

    ABSTRACT: Crystallization from lipidic mesophase matrices is a promising route to diffraction-quality crystals and structures of membrane proteins. The microfluidic approach reported here eliminates two bottlenecks of the standard mesophase-based crystallization protocols: (i) manual preparation of viscous mesophases and (ii) manual harvesting of often small and fragile protein crystals. In the approach reported here, protein-loaded mesophases are formulated in an X-ray transparent microfluidic chip using only 60 nL of the protein solution per crystallization trial. The X-ray transparency of the chip enables diffraction data collection from multiple crystals residing in microfluidic wells, eliminating the normally required manual harvesting and mounting of individual crystals. We validated our approach by on-chip crystallization of photosynthetic reaction center, a membrane protein from Rhodobacter sphaeroides, followed by solving its structure to a resolution of 2.5 Å using X-ray diffraction data collected on-chip under ambient conditions. A moderate conformational change in hydrophilic chains of the protein was observed when comparing the on-chip, room temperature structure with known structures for which data were acquired under cryogenic conditions.

  14. X-ray transparent microfluidic chip for mesophase-based crystallization of membrane proteins and on-chip structure determination

    DOE PAGES

    Khvostichenko, Daria S.; Schieferstein, Jeremy M.; Pawate, Ashtamurthy S.; ...

    2014-08-21

    Crystallization from lipidic mesophase matrices is a promising route to diffraction-quality crystals and structures of membrane proteins. The microfluidic approach reported here eliminates two bottlenecks of the standard mesophase-based crystallization protocols: (i) manual preparation of viscous mesophases and (ii) manual harvesting of often small and fragile protein crystals. In the approach reported here, protein-loaded mesophases are formulated in an X-ray transparent microfluidic chip using only 60 nL of the protein solution per crystallization trial. The X-ray transparency of the chip enables diffraction data collection from multiple crystals residing in microfluidic wells, eliminating the normally required manual harvesting and mounting ofmore » individual crystals. In addition, we validated our approach by on-chip crystallization of photosynthetic reaction center, a membrane protein from Rhodobacter sphaeroides, followed by solving its structure to a resolution of 2.5 Å using X-ray diffraction data collected on-chip under ambient conditions. A moderate conformational change in hydrophilic chains of the protein was observed when comparing the on-chip, room temperature structure with known structures for which data were acquired under cryogenic conditions.« less

  15. Design, fabrication and test of a microfluidic nebulizer chip for desorption electrospray ionization mass spectrometry

    PubMed Central

    Sen, A K; Darabi, J; Knapp, D R

    2009-01-01

    This paper presents design, microfabrication, and test of a microfluidic nebulizer chip for desorption electrospray ionization mass spectrometry (DESI-MS) in proteomic analysis. The microfluidic chip is fabricated using cyclic olefin copolymer (COC) substrates. The fluidic channels are thermally embossed onto a base substrate using a nickel master and then a top substrate is thermally bonded to seal the channels. Carbon ink embossed into the top COC substrate is used to established electrical connection between the external power supply and the liquid in the channel. The microfluidic chip to external capillary connection is fabricated using Nanoport™ interconnection system. Preliminary leakage test was performed to demonstrate the interconnection system is leak-free and pressure test was performed to evaluate the burst pressure. Finally, the nebulizer chip was used to perform DESI-MS for analyzing peptides (BSA and bradykinin) and reserpine on the nanoporous alumina surface. DESI-MS performance of the microfluidic nebulizer chip is compared with that obtained using a conventional DESI nebulizer. PMID:20161284

  16. Manually operatable on-chip bistable pneumatic microstructures for microfluidic manipulations.

    PubMed

    Chen, Arnold; Pan, Tingrui

    2014-09-07

    Bistable microvalves are of particular interest because of their distinct nature of requiring energy consumption only during the transition between the open and closed states. This characteristic can be highly advantageous in reducing the number of external inputs and the complexity of control circuitries since microfluidic devices as contemporary lab-on-a-chip platforms are transferring from research settings to low-resource environments with high integrability and a small form factor. In this paper, we first present manually operatable, on-chip bistable pneumatic microstructures (BPMs) for microfluidic manipulation. The structural design and operation of the BPM devices can be readily integrated into any pneumatically powered microfluidic network consisting of pneumatic and fluidic channels. It is mainly composed of a vacuum activation chamber (VAC) and a pressure release chamber (PRC), of which users have direct control through finger pressing to switch either to the bistable vacuum state (VS) or the atmospheric state (AS). We have integrated multiple BPM devices into a 4-to-1 microfluidic multiplexor to demonstrate on-chip digital flow switching from different sources. Furthermore, we have shown its clinical relevance in a point-of-care diagnostic chip that processes blood samples to identify the distinct blood types (A/B/O) on-chip.

  17. Fabrication of dielectrophoretic microfluidic chips using a facile screen-printing technique for microparticle trapping

    NASA Astrophysics Data System (ADS)

    Wee, Wei Hong; Li, Zedong; Hu, Jie; Adib Kadri, Nahrizul; Xu, Feng; Li, Fei; Pingguan-Murphy, Belinda

    2015-10-01

    Trapping of microparticles finds wide applications in numerous fields. Microfluidic chips based on a dielectrophoresis (DEP) technique hold several advantages for trapping microparticles, such as fast result processing, a small amount of sample required, high spatial resolution, and high accuracy of target selection. There is an unmet need to develop DEP microfluidic chips on different substrates for different applications in a low cost, facile, and rapid way. This study develops a new facile method based on a screen-printing technique for fabrication of electrodes of DEP chips on three types of substrates (i.e. polymethyl-methacrylate (PMMA), poly(ethylene terephthalate) and A4 paper). The fabricated PMMA-based DEP microfluidic chip was selected as an example and successfully used to trap and align polystyrene microparticles in a suspension and cardiac fibroblasts in a cell culture solution. The developed electrode fabrication method is compatible with different kinds of DEP substrates, which could expand the future application field of DEP microfluidic chips, including new forms of point-of care diagnostics and trapping circulating tumor cells.

  18. Manually Operatable On-Chip Bistable Pneumatic Microstructures for Microfluidic Manipulations

    PubMed Central

    Chen, A.; Pan, T.

    2014-01-01

    Bistable microvalves are of particular interest because of their distinct nature requiring energy consumption only during the transition between the open and closed states. This characteristic can be highly advantageous in reducing the number of external inputs and the complexity of control circuitries for microfluidic devices as contemporary lab-on-a-chip platforms are transferring from research settings to low-resource environments with high integratability and small form factor. In this paper, we first present manually operatable, on-chip bistable pneumatic microstructures (BPM) for microfluidic manipulation. The structural design and operation of the BPM devices can be readily integrated into any pneumatically powered microfluidic network consisting of pneumatic and fluidic channels. It is mainly comprised of a vacuum activation chamber (VAC) and a pressure release chamber (PRC), which users have direct control through finger pressing to switch between bistable vacuum state (VS) or atmospheric state (AS). We have integrated multiple BPM devices into a 4-to-1 microfluidic multiplexor to demonstrate on-chip digital flow switching from different sources. Furthermore, we have shown its clinical relevance in a point-of-care diagnostic chip that process blood samples to identify the distinct blood types (A/B/O) on chip. PMID:25007840

  19. Recent progress in preparation and application of microfluidic chip electrophoresis

    NASA Astrophysics Data System (ADS)

    Cong, Hailin; Xu, Xiaodan; Yu, Bing; Yuan, Hua; Peng, Qiaohong; Tian, Chao

    2015-05-01

    Since its discovery in 1990, microfluidic chip electrophoresis (MCE) has allowed the development of applications with small size, fast analysis, low cost, high integration density and automatic level, which are easy to carry and have made commercialization efficient. MCE has been widely used in the areas of environmental protection, biochemistry, medicine and health, clinical testing, judicial expertise, food sanitation, pharmaceutical checking, drug testing, agrochemistry, biomedical engineering and life science. As one of the foremost fields in the research of capillary electrophoresis, MCE is the ultimate frontier to develop the miniaturized, integrated, automated all-in-one instruments needed in modern analytical chemistry. By adopting the advanced technologies of micro-machining, lasers and microelectronics, and the latest research achievements in analytical chemistry and biochemistry, the sampling, separation and detection systems of commonly used capillary electrophoresis are integrated with high densities onto glass, quartz, silicon or polymer wafers to form the MCE, which can finish the analysis of multi-step operations such as injection, enrichment, reaction, derivatization, separation, and collection of samples in a portable, efficient and super high speed manner. With reference to the different technological achievements in this area, the latest developments in MCE are reviewed in this article. The preparation mechanisms, surface modifications, and properties of different materials in MCE are compared, and the different sampling, separation and detection systems in MCE are summarized. The performance of MCE in analysis of fluorescent substance, metallic ion, sugar, medicine, nucleic acid, DNA, amino acid, polypeptide and protein is discussed, and the future direction of development is forecast.

  20. Ex Situ Integration of Multifunctional Porous Polymer Monoliths into Thermoplastic Microfluidic Chips.

    PubMed

    Kendall, Eric L; Wienhold, Erik; Rahmanian, Omid D; DeVoe, Don L

    2014-10-31

    A unique method for incorporating functional porous polymer monolith elements into thermoplastic microfluidic chips is described. Monolith elements are formed in a microfabricated mold, rather than within the microchannels, and chemically functionalized off chip before insertion into solvent-softened thermoplastic microchannels during chip assembly. Because monoliths may be trimmed prior to final placement, control of their size, shape, and uniformity is greatly improved over in-situ photopolymerization methods. A characteristic trapezoidal profile facilitates rapid insertion and enables complete mechanical anchoring of the monolith periphery, eliminating the need for chemical attachment to the microchannel walls. Off-chip processing allows the parallel preparation of monoliths of differing compositions and surface chemistries in large batches. Multifunctional flow-through arrays of multiple monolith elements are demonstrated using this approach through the creation of a fluorescent immunosensor with integrated controls, and a microfluidic bubble separator comprising a combination of integrated hydrophobic and hydrophilic monolith elements.

  1. Ex Situ Integration of Multifunctional Porous Polymer Monoliths into Thermoplastic Microfluidic Chips

    PubMed Central

    Kendall, Eric L.; Wienhold, Erik; Rahmanian, Omid D.; DeVoe, Don L.

    2014-01-01

    A unique method for incorporating functional porous polymer monolith elements into thermoplastic microfluidic chips is described. Monolith elements are formed in a microfabricated mold, rather than within the microchannels, and chemically functionalized off chip before insertion into solvent-softened thermoplastic microchannels during chip assembly. Because monoliths may be trimmed prior to final placement, control of their size, shape, and uniformity is greatly improved over in-situ photopolymerization methods. A characteristic trapezoidal profile facilitates rapid insertion and enables complete mechanical anchoring of the monolith periphery, eliminating the need for chemical attachment to the microchannel walls. Off-chip processing allows the parallel preparation of monoliths of differing compositions and surface chemistries in large batches. Multifunctional flow-through arrays of multiple monolith elements are demonstrated using this approach through the creation of a fluorescent immunosensor with integrated controls, and a microfluidic bubble separator comprising a combination of integrated hydrophobic and hydrophilic monolith elements. PMID:25018587

  2. Error analysis for pesticide detection performed on paper-based microfluidic chip devices

    NASA Astrophysics Data System (ADS)

    Yang, Ning; Shen, Kai; Guo, Jianjiang; Tao, Xinyi; Xu, Peifeng; Mao, Hanping

    2017-07-01

    Paper chip is an efficient and inexpensive device for pesticide residues detection. However, the reasons of detection error are not clear, which is the main problem to hinder the development of pesticide residues detection. This paper focuses on error analysis for pesticide detection performed on paper-based microfluidic chip devices, which test every possible factor to build the mathematical models for detection error. In the result, double-channel structure is selected as the optimal chip structure to reduce detection error effectively. The wavelength of 599.753 nm is chosen since it is the most sensitive detection wavelength to the variation of pesticide concentration. At last, the mathematical models of detection error for detection temperature and prepared time are concluded. This research lays a theory foundation on accurate pesticide residues detection based on paper-based microfluidic chip devices.

  3. A microfluidic approach for protein structure determination at room temperature via on-chip anomalous diffraction.

    PubMed

    Perry, Sarah L; Guha, Sudipto; Pawate, Ashtamurthy S; Bhaskarla, Amrit; Agarwal, Vinayak; Nair, Satish K; Kenis, Paul J A

    2013-08-21

    We report a microfluidic approach for de novo protein structure determination via crystallization screening and optimization, as well as on-chip X-ray diffraction data collection. The structure of phosphonoacetate hydrolase (PhnA) has been solved to 2.11 Åvia on-chip collection of anomalous data that has an order of magnitude lower mosaicity than what is typical for traditional structure determination methods.

  4. Tough silk fibers prepared in air using a biomimetic microfluidic chip.

    PubMed

    Luo, Jie; Zhang, Lele; Peng, Qingfa; Sun, Mengjie; Zhang, Yaopeng; Shao, Huili; Hu, Xuechao

    2014-05-01

    Microfluidic chips with single channel were built to mimic the shear and elongation conditions in the spinning apparatus of spider and silkworm. Silk fibers dry-spun from regenerated silk fibroin (RSF) aqueous solution using the chip could be tougher than degummed natural silk. The artificial silk exhibited a breaking strength up to 614 MPa, a breaking elongation up to 27% and a breaking energy of 101 kJ/kg.

  5. Maskless fabrication of cell-laden microfluidic chips with localized surface functionalization for the co-culture of cancer cells.

    PubMed

    Hamid, Qudus; Wang, Chengyang; Snyder, Jessica; Williams, Shannon; Liu, Yigong; Sun, Wei

    2015-03-02

    The utilization of the microfabrication technique to fabricate advanced computing chips has exponentially increased in the last few decades. Needless to say, this fabrication technique offers some unique advantages to develop micro-systems. Though many conventional microfabrication techniques today uses very harsh chemicals, the authors believe that the manipulation of system components and fabrication methods may aid in the utilization of the microfabrication techniques used in fabricating computer chips to develop advanced biological microfluidic systems. Presented in this paper is a fabrication approach in which popular fabrication methods and techniques are coupled together to develop an integrated system that aids in the fabrication of cell-laden microfluidic systems. This system aims to reduce the uses of harsh chemicals and decreases the lengthy fabrication time. Additionally, this integrated system will enable the printing of cells as the microfluidic chip is being fabricated. To demonstrate the unique capabilities of the integrated system, an advanced microfluidic chip is being fabricated and investigated. The advanced chip will feature the investigation of cancer cells in a co-cultured microfluidic environment. The investigations presented demonstrate co-cultures in a microfluidic chip, advanced cell printing with localized surface enhancement, cell integration, and full additive fabrication of a microfluidic chip.

  6. Numerical design of microfluidic-microelectric hybrid chip for the separation of biological cells.

    PubMed

    Ye, Ting; Li, Hua; Lam, K Y

    2011-03-15

    A miniature microfluidic-microelectric hybrid chip is numerically designed for separation of biological cells, where the characteristic length of the chip is close to the cell radius. A mathematical model is developed to characterize the motion and deformation of a biological cell in the hydrodynamic and nonuniform electric coupled fields, in which the mechanical and dielectric behaviors of the cell are taken into consideration. Subsequently, the model is validated by comparing with the experimental results published previously. By taking a red blood cell (RBC) as the sample of biological cell, the chip structure is numerically designed from the viewpoints of the electrode width, fluid flow velocity, and electric potential, respectively. Using the designed microfluidic-microelectric hybrid chip, the effects of the shape and initial position of the RBC on the separation ability are then analyzed. After that, the separation of the RBCs with the different permittivities or conductivities using the designed chip is simulated, and the deformation behaviors of the RBCs are discussed as well. At the high frequency, the permittivities of the RBCs play a dominant role in the separation of the RBCs, which causes the RBCs moving toward or away from the electrode array. However, the conductivity of the RBC plays a significant role at the low frequency. With suitable suspending fluid therefore, the separation of cells with different permittivities or conductivities can be achieved using the microfluidic-microelectric hybrid chip designed by the present work.

  7. A Reduced Order Model for Whole-Chip Thermal Analysis of Microfluidic Lab-on-a-Chip Systems

    PubMed Central

    Wang, Yi; Song, Hongjun; Pant, Kapil

    2013-01-01

    This paper presents a Krylov subspace projection-based Reduced Order Model (ROM) for whole microfluidic chip thermal analysis, including conjugate heat transfer. Two key steps in the reduced order modeling procedure are described in detail, including (1) the acquisition of a 3D full-scale computational model in the state-space form to capture the dynamic thermal behavior of the entire microfluidic chip; and (2) the model order reduction using the Block Arnoldi algorithm to markedly lower the dimension of the full-scale model. Case studies using practically relevant thermal microfluidic chip are undertaken to establish the capability and to evaluate the computational performance of the reduced order modeling technique. The ROM is compared against the full-scale model and exhibits good agreement in spatiotemporal thermal profiles (<0.5% relative error in pertinent time scales) and over three orders-of-magnitude acceleration in computational speed. The salient model reusability and real-time simulation capability renders it amenable for operational optimization and in-line thermal control and management of microfluidic systems and devices. PMID:24443647

  8. An integrated digital microfluidic lab-on-a-chip for clinical diagnostics on human physiological fluids.

    PubMed

    Srinivasan, Vijay; Pamula, Vamsee K; Fair, Richard B

    2004-08-01

    Clinical diagnostics is one of the most promising applications for microfluidic lab-on-a-chip systems, especially in a point-of-care setting. Conventional microfluidic devices are usually based on continuous-flow in microchannels, and offer little flexibility in terms of reconfigurability and scalability. Handling of real physiological samples has also been a major challenge in these devices. We present an alternative paradigm--a fully integrated and reconfigurable droplet-based "digital" microfluidic lab-on-a-chip for clinical diagnostics on human physiological fluids. The microdroplets, which act as solution-phase reaction chambers, are manipulated using the electrowetting effect. Reliable and repeatable high-speed transport of microdroplets of human whole blood, serum, plasma, urine, saliva, sweat and tear, is demonstrated to establish the basic compatibility of these physiological fluids with the electrowetting platform. We further performed a colorimetric enzymatic glucose assay on serum, plasma, urine, and saliva, to show the feasibility of performing bioassays on real samples in our system. The concentrations obtained compare well with those obtained using a reference method, except for urine, where there is a significant difference due to interference by uric acid. A lab-on-a-chip architecture, integrating previously developed digital microfluidic components, is proposed for integrated and automated analysis of multiple analytes on a monolithic device. The lab-on-a-chip integrates sample injection, on-chip reservoirs, droplet formation structures, fluidic pathways, mixing areas and optical detection sites, on the same substrate. The pipelined operation of two glucose assays is shown on a prototype digital microfluidic lab-on-chip, as a proof-of-concept.

  9. Fuel cell-powered microfluidic platform for lab-on-a-chip applications.

    PubMed

    Esquivel, Juan Pablo; Castellarnau, Marc; Senn, Tobias; Löchel, Bernd; Samitier, Josep; Sabaté, Neus

    2012-01-07

    The achievement of a higher degree of integration of components--especially micropumps and power sources--is a challenge currently being pursued to obtain portable and totally autonomous microfluidic devices. This paper presents the integration of a micro direct methanol fuel cell (μDMFC) in a microfluidic platform as a smart solution to provide both electrical and pumping power to a Lab-on-a-Chip system. In this system the electric power produced by the fuel cell is available to enable most of the functionalites required by the microfluidic chip, while the generated CO(2) from the electrochemical reaction produces a pressure capable of pumping a liquid volume through a microchannel. The control of the fuel cell operating conditions allows regulation of the flow rate of a liquid sample through a microfluidic network. The relation between sample flow rate and the current generated by the fuel cell is practically linear, achieving values in the range of 4-18 μL min(-1) while having an available power between 1-4 mW. This permits adjusting the desired flow rate for a given application by controlling the fuel cell output conditions and foresees a fully autonomous analytical Lab-on-a-Chip in which the same device would provide the electrical power to a detection module and at the same time use the CO(2) pumping action to flow the required analytes through a particular microfluidic design.

  10. Microfluidic chips for point-of-care immunodiagnostics.

    PubMed

    Gervais, Luc; de Rooij, Nico; Delamarche, Emmanuel

    2011-06-24

    We might be at the turning point where research in microfluidics undertaken in academia and industrial research laboratories, and substantially sponsored by public grants, may provide a range of portable and networked diagnostic devices. In this Progress Report, an overview on microfluidic devices that may become the next generation of point-of-care (POC) diagnostics is provided. First, we describe gaps and opportunities in medical diagnostics and how microfluidics can address these gaps using the example of immunodiagnostics. Next, we conceptualize how different technologies are converging into working microfluidic POC diagnostics devices. Technologies are explained from the perspective of sample interaction with components of a device. Specifically, we detail materials, surface treatment, sample processing, microfluidic elements (such as valves, pumps, and mixers), receptors, and analytes in the light of various biosensing concepts. Finally, we discuss the integration of components into accurate and reliable devices.

  11. A single microfluidic chip with dual surface properties for protein drug delivery.

    PubMed

    Bokharaei, Mehrdad; Saatchi, Katayoun; Häfeli, Urs O

    2017-04-15

    Principles of double emulsion generation were incorporated in a glass microfluidic chip fabricated with two different surface properties in order to produce protein loaded polymer microspheres. The microspheres were produced by integrating two microfluidic flow focusing systems and a multi-step droplet splitting and mixing system into one chip. The chip consists of a hydrophobic and a hydrophilic section with two different heights, 12μm and 45μm, respectively. As a result, the protein is homogenously distributed throughout the polymer microsphere matrix, not just in its center (which has been studied before). In our work, the inner phase was bovine serum albumin (BSA) in phosphate buffered saline, the disperse phase was poly (lactic acid) in chloroform and the continuous phase was an aqueous solution of poly(vinyl alcohol). After solvent removal, BSA loaded microspheres with an encapsulation efficiency of up to 96% were obtained. Our results show the feasibility of producing microspheres loaded with a hydrophilic drug in a microfluidic system that integrates different microfluidic units into one chip. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Single-cell enzyme-free dissociation of neurospheres using a microfluidic chip.

    PubMed

    Lin, Ching-Hui; Lee, Don-Ching; Chang, Hao-Chen; Chiu, Ing-Ming; Hsu, Chia-Hsien

    2013-12-17

    Obtaining single dissociated cells from neurospheres is difficult using nonenzymatic methods. In this paper we report the development of a microfluidic-chip-based approach that utilizes flow and microstructures to dissociate neurospheres. We show that this microfluidic-chip-based neurosphere-dissociation method can generate high yields of single cells from dissociated neurospheres of mouse KT98 and DC115 cell models (passage number, 3-8; diameter range, 40-250 μm): 90% and 95%, respectively. The microfluidic-chip-dissociated cells had high viabilities (80-85%) and the ability to regrow into neurospheres, demonstrating the applicability of this device to neurosphere assay applications. In addition, the dissociated cells retained their normal differentiation potentials, as shown by their capabilities to differentiate into three neural lineages (neurons, astroglia, and oligodendrocytes) when cultured in differentiation culture conditions. Since this microfluidic-chip-based method does not require the use of enzymatic reagents, the risk of contamination from exogenous substances could be reduced, making it an attractive tool for a wide range of applications where neurosphere dissociation is needed.

  13. Chip in a lab: Microfluidics for next generation life science research

    PubMed Central

    Streets, Aaron M.; Huang, Yanyi

    2013-01-01

    Microfluidic circuits are characterized by fluidic channels and chambers with a linear dimension on the order of tens to hundreds of micrometers. Components of this size enable lab-on-a-chip technology that has much promise, for example, in the development of point-of-care diagnostics. Micro-scale fluidic circuits also yield practical, physical, and technological advantages for studying biological systems, enhancing the ability of researchers to make more precise quantitative measurements. Microfluidic technology has thus become a powerful tool in the life science research laboratory over the past decade. Here we focus on chip-in-a-lab applications of microfluidics and survey some examples of how small fluidic components have provided researchers with new tools for life science research. PMID:23460772

  14. Chip in a lab: Microfluidics for next generation life science research.

    PubMed

    Streets, Aaron M; Huang, Yanyi

    2013-01-01

    Microfluidic circuits are characterized by fluidic channels and chambers with a linear dimension on the order of tens to hundreds of micrometers. Components of this size enable lab-on-a-chip technology that has much promise, for example, in the development of point-of-care diagnostics. Micro-scale fluidic circuits also yield practical, physical, and technological advantages for studying biological systems, enhancing the ability of researchers to make more precise quantitative measurements. Microfluidic technology has thus become a powerful tool in the life science research laboratory over the past decade. Here we focus on chip-in-a-lab applications of microfluidics and survey some examples of how small fluidic components have provided researchers with new tools for life science research.

  15. A hybrid paper and microfluidic chip with electrowetting valves and colorimetric detection.

    PubMed

    He, Fei; Grimes, Jeff; Alcaine, Samuel D; Nugen, Sam R

    2014-06-21

    Sequential fluid delivery with minimized external equipment is vital towards a point-of-care diagnostic device. In this work, we have further developed the On-chip Electrowetting Valves concept for the sequential delivery of the reagents to the reaction site in a miniaturized capillary-driven microfluidic chip. Specifically, a disposable polymeric microfluidic device was developed containing capillary force driven microchannels. The device was fabricated using laser ablation and inkjet printing and required no external pumping equipment. The assay was conducted on the microchip containing microfluidic channels with embedded electrowetting valves and a porous membrane patterned with capture molecules and colloidal gold labels. To conduct the assay, the microchip was connected with a low voltage supply which was capable of sequentially opening the valves, delivering the sample and the rinsing reagent to generate visual results. Using T7 bacteriophage as a model, we have demonstrated the development of the device, operation of the valves and execution of the automated assay.

  16. Embellishment of microfluidic devices via femtosecond laser micronanofabrication for chip functionalization.

    PubMed

    Wang, Juan; He, Yan; Xia, Hong; Niu, Li-Gang; Zhang, Ran; Chen, Qi-Dai; Zhang, Yong-Lai; Li, Yan-Feng; Zeng, Shao-Jiang; Qin, Jian-Hua; Lin, Bing-Cheng; Sun, Hong-Bo

    2010-08-07

    This paper demonstrates the embellishment of existing microfluidic devices with integrated three dimensional (3D) micronanostructures via femtosecond laser micronanofabrication, which, for the first time, proves two-photon photopolymerization (TPP) to be a powerful technology for chip functionalization. As representative examples, microsieves with various pore shape and adjustable pore size were successfully fabricated inside a conventional glass-based microfluidic channel prepared by wet etching for microparticle separation. Moreover, a fish scale like microfilter was also fabricated and appointed as a one-way valve, which showed excellent performance as we expected. These results indicate that such embellishment of microfluidic devices is simple, low cost, flexible and easy to access. We believe that, combined with TPP, the application of lab-on-chip devices would be further extended.

  17. Science Issues Associated with the Use of a Microfluidic Chip Designed Specifically for Protein Crystallization

    NASA Technical Reports Server (NTRS)

    Holmes, Anna M.; Monaco, Lisa; Barnes, Cindy; Spearing, Scott; Jenkins, Andy; Johnson, Todd; Mayer, Derek; Cole, Helen

    2003-01-01

    The Iterative Biological Crystallization team in partnership with Caliper Technologies has produced a prototype microfluidic chip for batch crystallization that has been designed and tested. The chip is designed for the mixing and dispensing of up to five solutions with possible variation of the recipe being delivered to two growth wells. Developments that have led to the successful on-chip crystallization of a few model proteins have required investigative insight into many different areas, including fluid mixing dynamics, surface treatments, quantification and fidelity of reagent delivery. This presentation will encompass the ongoing studies and data accumulated toward these efforts.

  18. "Print-n-Shrink" technology for the rapid production of microfluidic chips and protein microarrays.

    PubMed

    Sollier, Kevin; Mandon, Céline A; Heyries, Kevin A; Blum, Loïc J; Marquette, Christophe A

    2009-12-21

    An innovative method for the production of microfluidic chips integrating protein spots is described. The technology, called "Print-n-Shrink", is based on the screen-printing of a microfluidic design (using a dielectric ink) onto Polyshrink polystyrene sheets. The initial print which has a minimum size of 15 microm (height) x 230 microm (width) is thermally treated (30 seconds, 163 degrees C) to shrink and generate features of 85 microm (height) x 100 microm (width). Concomitantly, proteins such as monoclonal antibodies or cellular adhesion proteins are spotted onto the Polyshrink sheets and shrunk together with the microfluidic design, creating a complete biochip integrating both complex microfluidic designs and protein spots for bioanalytical applications.

  19. Rapid detection of pathogens using antibody-coated microbeads with bioluminescence in microfluidic chips.

    PubMed

    Guan, Xiao; Zhang, Hui-jing; Bi, Yin-nan; Zhang, Li; Hao, Dun-ling

    2010-08-01

    Detection of pathogens was demonstrated in a polydimethylsiloxane (PDMS)/glass microfluidic chip with which microbead-based immunoseparation platform and the bioluminescence technology were integrated. Escherichia coli (E. coli) O157:H7 was used as the model bacteria. The microchamber in microfluidic chip was filled with glass beads coated with antibodies which could capture specific organism, and the capture efficiency of the chip for the bacteria was about 91.75% approximately 95.62%. Then the concentration of bacteria was determined by detecting adenosine triphosphate (ATP) employing bioluminescence reaction of firefly luciferin-lucifera-ATP on chip. The method allowed reliable detection of E. coli O157:H7 concentrations from 3.2 x 10(1) cfu/microL to 3.2 x 10(5) cfu/microL within 20 min. This research demonstrated excellent reproducibility, stability, and specificity, and could accurately detect the pathogenic bacteria in food samples. The microfluidic chip and the equipments used in this method are easy to miniaturize, thus the method has great potential to be developed to a portable device for rapid detection of pathogens.

  20. A PDMS-Based Microfluidic Hanging Drop Chip for Embryoid Body Formation.

    PubMed

    Wu, Huei-Wen; Hsiao, Yi-Hsing; Chen, Chih-Chen; Yet, Shaw-Fang; Hsu, Chia-Hsien

    2016-07-06

    The conventional hanging drop technique is the most widely used method for embryoid body (EB) formation. However, this method is labor intensive and limited by the difficulty in exchanging the medium. Here, we report a microfluidic chip-based approach for high-throughput formation of EBs. The device consists of microfluidic channels with 6 × 12 opening wells in PDMS supported by a glass substrate. The PDMS channels were fabricated by replicating polydimethyl-siloxane (PDMS) from SU-8 mold. The droplet formation in the chip was tested with different hydrostatic pressures to obtain optimal operation pressures for the wells with 1000 μm diameter openings. The droplets formed at the opening wells were used to culture mouse embryonic stem cells which could subsequently developed into EBs in the hanging droplets. This device also allows for medium exchange of the hanging droplets making it possible to perform immunochemistry staining and characterize EBs on chip.

  1. Microfluidic Gut-liver chip for reproducing the first pass metabolism.

    PubMed

    Choe, Aerim; Ha, Sang Keun; Choi, Inwook; Choi, Nakwon; Sung, Jong Hwan

    2017-03-01

    After oral intake of drugs, drugs go through the first pass metabolism in the gut and the liver, which greatly affects the final outcome of the drugs' efficacy and side effects. The first pass metabolism is a complex process involving the gut and the liver tissue, with transport and reaction occurring simultaneously at various locations, which makes it difficult to be reproduced in vitro with conventional cell culture systems. In an effort to tackle this challenge, here we have developed a microfluidic gut-liver chip that can reproduce the dynamics of the first pass metabolism. The microfluidic chip consists of two separate layers for gut epithelial cells (Caco-2) and the liver cells (HepG2), and is designed so that drugs go through a sequential absorption in the gut chamber and metabolic reaction in the liver chamber. We fabricated the chip and showed that the two different cell lines can be successfully co-cultured on chip. When the two cells are cultured on chip, changes in the physiological function of Caco-2 and HepG2 cells were noted. The cytochrome P450 metabolic activity of both cells were significantly enhanced, and the absorptive property of Caco-2 cells on chip also changed in response to the presence of flow. Finally, first pass metabolism of a flavonoid, apigenin, was evaluated as a model compound, and co-culture of gut and liver cells on chip resulted in a metabolic profile that is closer to the reported profile than a monoculture of gut cells. This microfluidic gut-liver chip can potentially be a useful platform to study the complex first pass metabolism of drugs in vitro.

  2. Direct-writing colloidal photonic crystal microfluidic chips by inkjet printing for label-free protein detection.

    PubMed

    Shen, Weizhi; Li, Mingzhu; Ye, Changqing; Jiang, Lei; Song, Yanlin

    2012-09-07

    Integrating photonic crystals (PC) into microfluidic systems has attracted immense interest for its novel functions. However, it is still a great challenge to fabricate PC microfluidic chips rapidly with complex functions. In this work, a direct-writing colloidal PC microchannel was firstly achieved by inkjet printing and was used for the surface-tension-confined microfluidic immune assay. PC channels with different structure colors have been successfully integrated on one chip. The fabricated chip has the advantages of rapid fabrication, quick fluidic transport and can monitor the fluidic fluxion using the naked eye. Utilizing this PC microfluidic chip, a colorimetric label-free immune assay was realized without nonspecific adsorption interference of the target.

  3. Digital Microfluidic Dynamic Culture of Mammalian Embryos on an Electrowetting on Dielectric (EWOD) Chip

    PubMed Central

    Huang, Hong-Yuan; Shen, Hsien-Hua; Tien, Chang-Hung; Li, Chin-Jung; Fan, Shih-Kang; Liu, Cheng-Hsien; Hsu, Wen-Syang; Yao, Da-Jeng

    2015-01-01

    Current human fertilization in vitro (IVF) bypasses the female oviduct and manually inseminates, fertilizes and cultivates embryos in a static microdrop containing appropriate chemical compounds. A microfluidic microchannel system for IVF is considered to provide an improved in-vivo-mimicking environment to enhance the development in a culture system for an embryo before implantation. We demonstrate a novel digitalized microfluidic device powered with electrowetting on a dielectric (EWOD) to culture an embryo in vitro in a single droplet in a microfluidic environment to mimic the environment in vivo for development of the embryo and to culture the embryos with good development and live births. Our results show that the dynamic culture powered with EWOD can manipulate a single droplet containing one mouse embryo and culture to the blastocyst stage. The rate of embryo cleavage to a hatching blastocyst with a dynamic culture is significantly greater than that with a traditional static culture (p<0.05). The EWOD chip enhances the culture of mouse embryos in a dynamic environment. To test the reproductive outcome of the embryos collected from an EWOD chip as a culture system, we transferred embryos to pseudo-pregnant female mice and produced live births. These results demonstrate that an EWOD-based microfluidic device is capable of culturing mammalian embryos in a microfluidic biological manner, presaging future clinical application. PMID:25933003

  4. Digital Microfluidic Dynamic Culture of Mammalian Embryos on an Electrowetting on Dielectric (EWOD) Chip.

    PubMed

    Huang, Hong-Yuan; Shen, Hsien-Hua; Tien, Chang-Hung; Li, Chin-Jung; Fan, Shih-Kang; Liu, Cheng-Hsien; Hsu, Wen-Syang; Yao, Da-Jeng

    2015-01-01

    Current human fertilization in vitro (IVF) bypasses the female oviduct and manually inseminates, fertilizes and cultivates embryos in a static microdrop containing appropriate chemical compounds. A microfluidic microchannel system for IVF is considered to provide an improved in-vivo-mimicking environment to enhance the development in a culture system for an embryo before implantation. We demonstrate a novel digitalized microfluidic device powered with electrowetting on a dielectric (EWOD) to culture an embryo in vitro in a single droplet in a microfluidic environment to mimic the environment in vivo for development of the embryo and to culture the embryos with good development and live births. Our results show that the dynamic culture powered with EWOD can manipulate a single droplet containing one mouse embryo and culture to the blastocyst stage. The rate of embryo cleavage to a hatching blastocyst with a dynamic culture is significantly greater than that with a traditional static culture (p<0.05). The EWOD chip enhances the culture of mouse embryos in a dynamic environment. To test the reproductive outcome of the embryos collected from an EWOD chip as a culture system, we transferred embryos to pseudo-pregnant female mice and produced live births. These results demonstrate that an EWOD-based microfluidic device is capable of culturing mammalian embryos in a microfluidic biological manner, presaging future clinical application.

  5. Electrochemical microfluidic chip based on molecular imprinting technique applied for therapeutic drug monitoring.

    PubMed

    Liu, Jiang; Zhang, Yu; Jiang, Min; Tian, Liping; Sun, Shiguo; Zhao, Na; Zhao, Feilang; Li, Yingchun

    2017-05-15

    In this work, a novel electrochemical detection platform was established by integrating molecularly imprinting technique with microfluidic chip and applied for trace measurement of three therapeutic drugs. The chip foundation is acrylic panel with designed grooves. In the detection cell of the chip, a Pt wire is used as the counter electrode and reference electrode, and a Au-Ag alloy microwire (NPAMW) with 3D nanoporous surface modified with electro-polymerized molecularly imprinted polymer (MIP) film as the working electrode. Detailed characterization of the chip and the working electrode was performed, and the properties were explored by cyclic voltammetry and electrochemical impedance spectroscopy. Two methods, respectively based on electrochemical catalysis and MIP/gate effect were employed for detecting warfarin sodium by using the prepared chip. The linearity of electrochemical catalysis method was in the range of 5×10(-6)-4×10(-4)M, which fails to meet clinical testing demand. By contrast, the linearity of gate effect was 2×10(-11)-4×10(-9)M with remarkably low detection limit of 8×10(-12)M (S/N=3), which is able to satisfy clinical assay. Then the system was applied for 24-h monitoring of drug concentration in plasma after administration of warfarin sodium in rabbit, and the corresponding pharmacokinetic parameters were obtained. In addition, the microfluidic chip was successfully adopted to analyze cyclophosphamide and carbamazepine, implying its good versatile ability. It is expected that this novel electrochemical microfluidic chip can act as a promising format for point-of-care testing via monitoring different analytes sensitively and conveniently. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Capillary-driven microfluidic chips with evaporation-induced flow control and dielectrophoretic microbead trapping

    NASA Astrophysics Data System (ADS)

    Temiz, Yuksel; Skorucak, Jelena; Delamarche, Emmanuel

    2014-07-01

    This work reports our efforts on developing simple-to-use microfluidic devices for point-of-care diagnostic applications with recent extensions that include the trapping of microbeads using dielectrophoresis (DEP) and the modulation of the liquid flow using integrated microheaters. DEP serves the purpose of trapping microbeads coated with receptors and analytes for detection of a fluorescent signal. The microheater is actuated once the chip is filled by capillarity, creating an evaporation-induced flow tuned according to assay conditions. The chips are composed of a glass substrate patterned with 50-nm-thick Pd electrodes and microfluidic structures made using a 20-μm-thick dry-film resist (DFR). Chips are covered/sealed by low temperature (50°C) lamination of a 50-μm-thick DFR layer having excellent optical and mechanical properties. To separate cleaned and sealed chips from the wafer, we used an effective chip singulation technique which we informally call the "chip-olate" process. In the experimental section, we first studied dielectrophoretic trapping of 10-μm beads for flow rates ranging from 80 pL s-1 to 2.5 nL s-1 that are generated by an external syringe pump. Then, we characterized the embedded microheater in DFR-covered chips. Flow rates as high as 8 nL s-1 were generated by evaporation-induced flow when the heater was biased by 10 V, corresponding to 270-mW power. Finally, DEP-based trapping and fluorescent detection of functionalized beads were demonstrated as the flow was generated by evaporation-induced flow after the microfluidic structures were filled by capillarity.

  7. Two-stage microfluidic chip for selective isolation of circulating tumor cells (CTCs).

    PubMed

    Hyun, Kyung-A; Lee, Tae Yoon; Lee, Su Hyun; Jung, Hyo-Il

    2015-05-15

    Over the past few decades, circulating tumor cells (CTCs) have been studied as a means of overcoming cancer. However, the rarity and heterogeneity of CTCs have been the most significant hurdles in CTC research. Many techniques for CTC isolation have been developed and can be classified into positive enrichment (i.e., specifically isolating target cells using cell size, surface protein expression, and so on) and negative enrichment (i.e., specifically eluting non-target cells). Positive enrichment methods lead to high purity, but could be biased by their selection criteria, while the negative enrichment methods have relatively low purity, but can isolate heterogeneous CTCs. To compensate for the known disadvantages of the positive and negative enrichments, in this study we introduced a two-stage microfluidic chip. The first stage involves a microfluidic magnetic activated cell sorting (μ-MACS) chip to elute white blood cells (WBCs). The second stage involves a geometrically activated surface interaction (GASI) chip for the selective isolation of CTCs. We observed up to 763-fold enrichment in cancer cells spiked into 5 mL of blood sample using the μ-MACS chip at 400 μL/min flow rate. Cancer cells were successfully separated with separation efficiencies ranging from 10.19% to 22.91% based on their EpCAM or HER2 surface protein expression using the GASI chip at a 100 μL/min flow rate. Our two-stage microfluidic chips not only isolated CTCs from blood cells, but also classified heterogeneous CTCs based on their characteristics. Therefore, our chips can contribute to research on CTC heterogeneity of CTCs, and, by extension, personalized cancer treatment.

  8. Construction of 3D multicellular microfluidic chip for an in vitro skin model.

    PubMed

    Lee, Sojin; Jin, Seon-Pil; Kim, Yeon Kyung; Sung, Gun Yong; Chung, Jin Ho; Sung, Jong Hwan

    2017-06-01

    Current in vitro skin models do not recapitulate the complex architecture and functions of the skin tissue. In particular, on-chip construction of an in vitro model comprising the epidermis and dermis layer with vascular structure for mass transport has not been reported yet. In this study, we aim to develop a microfluidic, three-dimensional (3D) skin chip with fluidic channels using PDMS and hydrogels. Mass transport within the collagen hydrogel matrix was verified with fluorescent model molecules, and a transport-reaction model of oxygen and glucose inside the skin chip was developed to aid the design of the microfluidic skin chip. Comparison of viabilities of dermal fibroblasts and HaCaT cultured in the chip with various culture conditions revealed that the presence of flow plays a crucial role in maintaining the viability, and both cells were viable after 10 days of air exposure culture. Our 3D skin chip with vascular structures can be a valuable in vitro model for reproducing the interaction between different components of the skin tissue, and thus work as a more physiologically realistic platform for testing skin reaction to cosmetic products and drugs.

  9. Easy-to-use microfluidic chip for long-term 3D-cell cultures

    NASA Astrophysics Data System (ADS)

    Bunge, Frank; van den Driesche, Sander; Vellekoop, Michael J.

    2017-05-01

    We present a microfluidic chip for an easy setup of a 3D-culture of mammalian cells. The chip contains feeding structures and gas supply for long-term cultivation of mammalian cells. The device is fabricated out of hard materials like silicon and glass that are all highly biocompatible. The chip uses the concept of surficial phaseguides that allows the partial filling of a microfluidic chip with liquids based on hydrophobic and hydrophilic surfaces. Here, a suspension of mammalian cells and melted agarose is filled into the chip and is pulled by the capillary pressure on the hydrophilic areas but not on the hydrophobic phaseguides. Consequently, only a part of the chip is filled with the agarose which gels by cooling a form the 3D-cell culture. The unfilled areas are used as supply structures for nutrition and gases. So the supply is based on diffusion and the supply of nutrition and gases is controlled independently. We cultured HaCaT-cells over 24 hours in our device and achieve a good viability.

  10. Identification of microfluidic two-phase flow patterns in lab-on-chip devices.

    PubMed

    Yang, Zhaochu; Dong, Tao; Halvorsen, Einar

    2014-01-01

    This work describes a capacitive sensor for identification of microfluidic two-phase flow in lab-on-chip devices. With interdigital electrodes and thin insulation layer utilized, this sensor is capable of being integrated with the microsystems easily. Transducing principle and design considerations are presented with respect to the microfluidic gas/liquid flow patterns. Numerical simulation results verify the operational principle. And the factors affecting the performance of the sensor are discussed. Besides, a feasible process flow for the fabrication is also proposed.

  11. Optical fiber LPG biosensor integrated microfluidic chip for ultrasensitive glucose detection

    PubMed Central

    Yin, Ming-jie; Huang, Bobo; Gao, Shaorui; Zhang, A. Ping; Ye, Xuesong

    2016-01-01

    An optical fiber sensor integrated microfluidic chip is presented for ultrasensitive detection of glucose. A long-period grating (LPG) inscribed in a small-diameter single-mode fiber (SDSMF) is employed as an optical refractive-index (RI) sensor. With the layer-by-layer (LbL) self-assembly technique, poly (ethylenimine) (PEI) and poly (acrylic acid) (PAA) multilayer film is deposited on the SDSMF-LPG sensor for both supporting and signal enhancement, and then a glucose oxidase (GOD) layer is immobilized on the outer layer for glucose sensing. A microfluidic chip for glucose detection is fabricated after embedding the SDSMF-LPG biosensor into the microchannel of the chip. Experimental results reveal that the SDSMF-LPG biosensor based on such a hybrid sensing film can ultrasensitively detect glucose concentration as low as 1 nM. After integration into the microfluidic chip, the detection range of the sensor is extended from 2 µM to 10 µM, and the response time is remarkablely shortened from 6 minutes to 70 seconds. PMID:27231643

  12. Design and implementation of a microfluidic half adder chip based on double-stranded DNA.

    PubMed

    Wang, Jing; Huang, Yourui

    2014-06-01

    In recent years, DNA computing has gained significant research interest. The design of a biochip with DNA computing as a carrier has become a key area in the development of a DNA molecular computer. The half adder, as the basic unit of various arithmetic units, has a complex structure that directly affects the overall complexity of a computer's structure. In this study, a half adder on a microfluidic chip is developed by means of bio-reaction. This technology is combined with a biochip and adopts glass and polydimethylsiloxane to fabricate a microscale hybrid chip. Using a DNA strand as an operand, realization of the half adder on a microfluidic chip is achieved by controlling the annealing and denaturation of double-stranded DNA. The computing results are rapidly and accurately obtained by detecting the presence of double-stranded DNA in a solution by agarose gel electrophoresis. The microfluidic half-adder chip accurately realizes half-adder computations and overcomes the shortcomings of traditional integrated circuit half adders, optical half adders, and chemical molecule half adders, such as complex structure, limited component size, and low accuracy.

  13. Microfluidic chip-based technologies: emerging platforms for cancer diagnosis

    PubMed Central

    2013-01-01

    The development of early and personalized diagnostic protocols is considered the most promising avenue to decrease mortality from cancer and improve outcome. The emerging microfluidic-based analyzing platforms hold high promises to fulfill high-throughput and high-precision screening with reduced equipment cost and low analysis time, as compared to traditional bulky counterparts in bench-top laboratories. This article overviewed the potential applications of microfluidic technologies for detection and monitoring of cancer through nucleic acid and protein biomarker analysis. The implications of the technologies in cancer cytology that can provide functional personalized diagnosis were highlighted. Finally, the future niches for using microfluidic-based systems in tumor screening were briefly discussed. PMID:24070124

  14. Parallel-plate lab-on-a-chip based on digital microfluidics for on-chip electrochemical analysis

    NASA Astrophysics Data System (ADS)

    Yu, Yuhua; Chen, Jianfeng; Zhou, Jia

    2014-01-01

    This paper describes an electrowetting on dielectric (EWOD) digital microfluidic-based lab-on-a-chip (LOC) integrated with on-chip electrochemical microsensor by IC compatible fabrication process, and its application for the entire online biosensing process capable of fully automatic analysis for ferrocenemethanol (FcM) and dopamine (DA). In this work, we made full use of the parallel-plate structure of the EWOD digital microfluidic device to fabricate the microfluidic module on the bottom plate and the three-microelectrode-system-integrated electrochemical cell together with patterned ground electrode on the top plate. The proposed LOC possesses the multifunction of: (1) creating, merging and transporting of microliter-level sample droplets, (2) online biosensing, and (3) droplets recycling. The three-electrode-integrated microsensor not only reveals a sensitive electrochemical detection for FcM in a wide concentration range (10 µM-1.0 mM), but also shows good stability, selectivity and reproducibility for surface-controlled detection of DA. The calibration of DA was linear for concentration from 1.0 to 50.0 µM with a high sensitivity of 2145 nA µM-1 cm-2 (R2 = 0.9933) and estimated detection limit of 0.42 µM (signal/noise ratio of 3). This work shows the promise of state-of-the-art digital microfluidic biosensors for fully automatic online bioanalysis in a future LOC to perform on-chip biomedical protocols in vitro diagnostic assays.

  15. Microfluidic organ-on-chip technology for blood-brain barrier research

    PubMed Central

    van der Helm, Marinke W; van der Meer, Andries D; Eijkel, Jan C T; van den Berg, Albert; Segerink, Loes I

    2016-01-01

    ABSTRACT Organs-on-chips are a new class of microengineered laboratory models that combine several of the advantages of current in vivo and in vitro models. In this review, we summarize the advances that have been made in the development of organ-on-chip models of the blood-brain barrier (BBBs-on-chips) and the challenges that are still ahead. The BBB is formed by specialized e3ndothelial cells and separates blood from brain tissue. It protects the brain from harmful compounds from the blood and provides homeostasis for optimal neuronal function. Studying BBB function and dysfunction is important for drug development and biomedical research. Microfluidic BBBs-on-chips enable real-time study of (human) cells in an engineered physiological microenvironment, for example incorporating small geometries and fluid flow as well as sensors. Examples of BBBs-on-chips in literature already show the potential of more realistic microenvironments and the study of organ-level functions. A key challenge in the field of BBB-on-chip development is the current lack of standardized quantification of parameters such as barrier permeability and shear stress. This limits the potential for direct comparison of the performance of different BBB-on-chip models to each other and existing models. We give recommendations for further standardization in model characterization and conclude that the rapidly emerging field of BBB-on-chip models holds great promise for further studies in BBB biology and drug development. PMID:27141422

  16. Microfluidic organ-on-chip technology for blood-brain barrier research.

    PubMed

    van der Helm, Marinke W; van der Meer, Andries D; Eijkel, Jan C T; van den Berg, Albert; Segerink, Loes I

    2016-01-01

    Organs-on-chips are a new class of microengineered laboratory models that combine several of the advantages of current in vivo and in vitro models. In this review, we summarize the advances that have been made in the development of organ-on-chip models of the blood-brain barrier (BBBs-on-chips) and the challenges that are still ahead. The BBB is formed by specialized endothelial cells and separates blood from brain tissue. It protects the brain from harmful compounds from the blood and provides homeostasis for optimal neuronal function [corrected]. Studying BBB function and dysfunction is important for drug development and biomedical research. Microfluidic BBBs-on-chips enable real-time study of (human) cells in an engineered physiological microenvironment, for example incorporating small geometries and fluid flow as well as sensors. Examples of BBBs-on-chips in literature already show the potential of more realistic microenvironments and the study of organ-level functions. A key challenge in the field of BBB-on-chip development is the current lack of standardized quantification of parameters such as barrier permeability and shear stress. This limits the potential for direct comparison of the performance of different BBB-on-chip models to each other and existing models. We give recommendations for further standardization in model characterization and conclude that the rapidly emerging field of BBB-on-chip models holds great promise for further studies in BBB biology and drug development.

  17. Macroporous microcarriers for introducing cells into a microfluidic chip.

    PubMed

    Bergström, G; Nilsson, K; Mandenius, C-F; Robinson, N D

    2014-09-21

    Macroporous gelatin beads (CultiSpher™ microcarriers) provide a convenient method for rapidly and reliably introducing cells cultured ex situ into a microfluidic device, where the spheres create a 3D environment for continued cell proliferation. We demonstrate the usefulness of this technique with a proof-of-concept viability analysis of cardiac cells after treatment with doxorubicin.

  18. Interfacial tension based on-chip extraction of microparticles confined in microfluidic Stokes flows

    NASA Astrophysics Data System (ADS)

    Huang, Haishui; He, Xiaoming

    2014-10-01

    Microfluidics involving two immiscible fluids (oil and water) has been increasingly used to produce hydrogel microparticles with wide applications. However, it is difficult to extract the microparticles out of the microfluidic Stokes flows of oil that have a Reynolds number (the ratio of inertia to viscous force) much less than one, where the dominant viscous force tends to drive the microparticles to move together with the surrounding oil. Here, we present a passive method for extracting hydrogel microparticles in microfluidic Stokes flow from oil into aqueous extracting solution on-chip by utilizing the intrinsic interfacial tension between oil and the microparticles. We further reveal that the thickness of an "extended confining layer" of oil next to the interface between oil and aqueous extracting solution must be smaller than the radius of microparticles for effective extraction. This method uses a simple planar merging microchannel design that can be readily fabricated and further integrated into a fluidic system to extract microparticles for wide applications.

  19. Single-use thermoplastic microfluidic burst valves enabling on-chip reagent storage.

    PubMed

    Rahmanian, Omid D; DeVoe, Don L

    2015-05-01

    A simple and reliable method for fabricating single-use normally closed burst valves in thermoplastic microfluidic devices is presented, using a process flow that is readily integrated into established workflows for the fabrication of thermoplastic microfluidics. An experimental study of valve performance reveals the relationships between valve geometry and burst pressure. The technology is demonstrated in a device employing multiple valves engineered to actuate at different inlet pressures that can be generated using integrated screw pumps. On-chip storage and reconstitution of fluorescein salt sealed within defined reagent chambers are demonstrated. By taking advantage of the low gas and water permeability of cyclic olefin copolymer, the robust burst valves allow on-chip hermetic storage of reagents, making the technology well suited for the development of integrated and disposable assays for use at the point of care.

  20. Validation of a fully autonomous phosphate analyser based on a microfluidic lab-on-a-chip.

    PubMed

    Slater, C; Cleary, J; Lau, K-T; Snakenborg, D; Corcoran, B; Kutter, J P; Diamond, D

    2010-01-01

    This work describes the design of a phosphate analyser that utilises a microfluidic lab-on-a-chip. The analyser contains all the required chemical storage, pumping and electronic components to carry out a complete phosphate assay. The system is self-calibrating and self-cleaning, thus capable of long-term operation. This was proven by a bench top calibration of the analyser using standard solutions and also by comparing the analyser's performance to a commercially available phosphate monitor installed at a waste water treatment plant. The output of the microfluidic lab-on-a-chip analyser was shown to have sensitivity and linear range equivalent to the commercially available monitor and also the ability to operate over an extended period of time.

  1. Droplet-based Biosensing for Lab-on-a-Chip, Open Microfluidics Platforms.

    PubMed

    Dak, Piyush; Ebrahimi, Aida; Swaminathan, Vikhram; Duarte-Guevara, Carlos; Bashir, Rashid; Alam, Muhammad A

    2016-04-14

    Low cost, portable sensors can transform health care by bringing easily available diagnostic devices to low and middle income population, particularly in developing countries. Sample preparation, analyte handling and labeling are primary cost concerns for traditional lab-based diagnostic systems. Lab-on-a-chip (LoC) platforms based on droplet-based microfluidics promise to integrate and automate these complex and expensive laboratory procedures onto a single chip; the cost will be further reduced if label-free biosensors could be integrated onto the LoC platforms. Here, we review some recent developments of label-free, droplet-based biosensors, compatible with "open" digital microfluidic systems. These low-cost droplet-based biosensors overcome some of the fundamental limitations of the classical sensors, enabling timely diagnosis. We identify the key challenges that must be addressed to make these sensors commercially viable and summarize a number of promising research directions.

  2. Microfluidic Organ/Body-on-a-Chip Devices at the Convergence of Biology and Microengineering.

    PubMed

    Perestrelo, Ana Rubina; Águas, Ana C P; Rainer, Alberto; Forte, Giancarlo

    2015-12-10

    Recent advances in biomedical technologies are mostly related to the convergence of biology with microengineering. For instance, microfluidic devices are now commonly found in most research centers, clinics and hospitals, contributing to more accurate studies and therapies as powerful tools for drug delivery, monitoring of specific analytes, and medical diagnostics. Most remarkably, integration of cellularized constructs within microengineered platforms has enabled the recapitulation of the physiological and pathological conditions of complex tissues and organs. The so-called "organ-on-a-chip" technology, which represents a new avenue in the field of advanced in vitro models, with the potential to revolutionize current approaches to drug screening and toxicology studies. This review aims to highlight recent advances of microfluidic-based devices towards a body-on-a-chip concept, exploring their technology and broad applications in the biomedical field.

  3. Rheology of conductive ink flow for printed electronics on a microfluidic chip

    NASA Astrophysics Data System (ADS)

    Jang, Young-Sik; Song, Simon

    2012-07-01

    Printed electronics have recently attracted extensive attention due to their superior productivity to conventional semiconductor fabrication methods. To develop printing devices optimized for printed electronics, numerical studies on ink flows are often necessary, and, therefore, it is critical to provide accurate ink properties for reliable numerical results. However, it is difficult to find such data in literature since inks for printed electronics contains conductive metallic nanoparticles and they are not only non-Newtonian but expensive. Thus, we propose utilizing a microfluidic chip to investigate rheological properties of conductive inks. By using micro particle image velocimeter along with an immersion oil technique, we examine the flow characteristics of two commercial conductive inks containing Ag nanoparticles on microfluidic chips. We found that the ink flows show a stronger shear-thinning behavior as the Ag content increases. Finally, suitable rheological models applicable to numerical simulations for those inks are suggested after comparing the experimental data to frequently used rheological models.

  4. Computationally Informed Design of a Multi-Axial Actuated Microfluidic Chip Device.

    PubMed

    Gizzi, Alessio; Giannitelli, Sara Maria; Trombetta, Marcella; Cherubini, Christian; Filippi, Simonetta; De Ninno, Adele; Businaro, Luca; Gerardino, Annamaria; Rainer, Alberto

    2017-07-14

    This paper describes the computationally informed design and experimental validation of a microfluidic chip device with multi-axial stretching capabilities. The device, based on PDMS soft-lithography, consisted of a thin porous membrane, mounted between two fluidic compartments, and tensioned via a set of vacuum-driven actuators. A finite element analysis solver implementing a set of different nonlinear elastic and hyperelastic material models was used to drive the design and optimization of chip geometry and to investigate the resulting deformation patterns under multi-axial loading. Computational results were cross-validated by experimental testing of prototypal devices featuring the in silico optimized geometry. The proposed methodology represents a suite of computationally handy simulation tools that might find application in the design and in silico mechanical characterization of a wide range of stretchable microfluidic devices.

  5. Droplet-based Biosensing for Lab-on-a-Chip, Open Microfluidics Platforms

    PubMed Central

    Dak, Piyush; Ebrahimi, Aida; Swaminathan, Vikhram; Duarte-Guevara, Carlos; Bashir, Rashid; Alam, Muhammad A.

    2016-01-01

    Low cost, portable sensors can transform health care by bringing easily available diagnostic devices to low and middle income population, particularly in developing countries. Sample preparation, analyte handling and labeling are primary cost concerns for traditional lab-based diagnostic systems. Lab-on-a-chip (LoC) platforms based on droplet-based microfluidics promise to integrate and automate these complex and expensive laboratory procedures onto a single chip; the cost will be further reduced if label-free biosensors could be integrated onto the LoC platforms. Here, we review some recent developments of label-free, droplet-based biosensors, compatible with “open” digital microfluidic systems. These low-cost droplet-based biosensors overcome some of the fundamental limitations of the classical sensors, enabling timely diagnosis. We identify the key challenges that must be addressed to make these sensors commercially viable and summarize a number of promising research directions. PMID:27089377

  6. Single-use thermoplastic microfluidic burst valves enabling on-chip reagent storage

    PubMed Central

    Rahmanian, Omid D.

    2014-01-01

    A simple and reliable method for fabricating single-use normally closed burst valves in thermoplastic microfluidic devices is presented, using a process flow that is readily integrated into established workflows for the fabrication of thermoplastic microfluidics. An experimental study of valve performance reveals the relationships between valve geometry and burst pressure. The technology is demonstrated in a device employing multiple valves engineered to actuate at different inlet pressures that can be generated using integrated screw pumps. On-chip storage and reconstitution of fluorescein salt sealed within defined reagent chambers are demonstrated. By taking advantage of the low gas and water permeability of cyclic olefin copolymer, the robust burst valves allow on-chip hermetic storage of reagents, making the technology well suited for the development of integrated and disposable assays for use at the point of care. PMID:25972774

  7. Microbubble movement during its formation in a co-flowing liquid in a microfluidic chip

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Qin, Hongwei; Jiang, Weikang; Jiang, Shengyuan; Sun, Lixia; Ren, Yukun; Li, Peng

    2017-08-01

    Microbubble formation surrounded by a co-flowing lqiud (CFL) in a new-designed microfluidic chip was investigated in the present study. The movement of microbubble and the effect of CFL and nitrogen pressure on it during its formation were mainly focused. A new microfluidic chip was fabricated to realize the co-axial flowing condition of liquid. Experimental works were conducted based on the professionally-constucted high-speed microscopic camera system (HSMCS). Two concerned parameters which represent the movement of target microbubble were introduced. Experimental data and analysis results indicated that microbubble moves along the formation direction as time with a quadratic law. Futhermore, both nitrogen presussure and CFL contribute to the formation process drastically but from different aspects. The present study provided empirical references for studies in the movement of microbubble during its formation in CFL which contributes to realize the accurate controllability in diameter and size distribution of microbubbles.

  8. Electrotaxis Studies of Lung Cancer Cells using a Multichannel Dual-electric-field Microfluidic Chip.

    PubMed

    Hou, Hsien-San; Chang, Hui-Fang; Cheng, Ji-Yen

    2015-12-29

    The behavior of directional cell migration under a direct current electric-field (dcEF) is referred to as electrotaxis. The significant role of physiological dcEF in guiding cell movement during embryo development, cell differentiation, and wound healing has been demonstrated in many studies. By applying microfluidic chips to an electrotaxis assay, the investigation process is shortened and experimental errors are minimized. In recent years, microfluidic devices made of polymeric substances (e.g., polymethylmethacrylate, PMMA, or acrylic) or polydimethylsiloxane (PDMS) have been widely used in studying the responses of cells to electrical stimulation. However, unlike the numerous steps required to fabricate a PDMS device, the simple and rapid construction of the acrylic microfluidic chip makes it suitable for both device prototyping and production. Yet none of the reported devices facilitate the efficient study of the simultaneous chemical and dcEF effects on cells. In this report, we describe our design and fabrication of an acrylic-based multichannel dual-electric-field (MDF) chip to investigate the concurrent effect of chemical and electrical stimulation on lung cancer cells. The MDF chip provides eight combinations of electrical/chemical stimulations in a single test. The chip not only greatly shortens the required experimental time but also increases accuracy in electrotaxis studies.

  9. Capillary-driven multiparametric microfluidic chips for one-step immunoassays.

    PubMed

    Gervais, Luc; Hitzbleck, Martina; Delamarche, Emmanuel

    2011-09-15

    Here we present a capillary-driven microfluidic chip for "one-step" immunoassays. The chip allows for easy modification of several assay parameters such as the flow rates of sample, the volumes of samples for tests, and the type of reagents and receptors for detecting analytes. We therefore term such a chip a multiparametric chip and illustrate this concept with the integration and release of anti-C-reactive protein (CRP) detection antibodies (dAbs) together with splitting flow of samples containing CRP across lines of anti-CRP capture antibodies (cAbs). The microfluidic chip is fabricated in Si and is sealed with polydimethylsiloxane (PDMS) patterned with cAbs. The microfluidic chip is ∼1.7×3.4 cm(2) and is capable of analyzing 20 μL of human serum in 6 parallel flow paths with a range of flow rates from 3.3 nL s(-1) to 0.46 nL s(-1). An inkjet spotter was used to deposit 10.6 nL of dAb solution in a structure vicinal to the main flow path of the chip. The consequent asymmetric release of dAbs in a stream of human serum is compensated by a Dean flow mixer having 9 mixing loops and a footprint of 2.8 mm × 0.78 mm. The quantity of dAb present in the half of the flow path close to the spotting region decreases from 83% at the entrance of the mixer to 52% in the region after the mixer. The sample is then equally split into 6 reaction chambers and proceeds via connecting channels to 2 μL capillary pumps. The hydraulic resistance of the connecting channels is designed to vary flow rates, and therefore the kinetics of capture of CRP-dAb complexes, from 10 min to 72 min. The increased incubation time leads to a fourfold increase in detection signal in the reaction chamber with the longer incubation time. The concept presented here is flexible and suited for implementing various surface fluorescence immunoassays on a capillary-driven microfluidic chip.

  10. Spatially resolved shear distribution in microfluidic chip for studying force transduction mechanisms in cells.

    PubMed

    Wang, Jianbin; Heo, Jinseok; Hua, Susan Z

    2010-01-21

    Fluid shear stress has profound effects on cell physiology. Here we present a versatile microfluidic method capable of generating variable magnitudes, gradients, and different modes of shear flow, to study sensory and force transduction mechanisms in cells. The chip allows cell culture under spatially resolved shear flow conditions as well as study of cell response to shear flow in real-time. Using this chip, we studied the effects of chronic shear stress on cellular functions of Madin-Darby Canine Kidney (MDCK), renal epithelial cells. We show that shear stress causes reorganization of actin cytoskeleton, which suppresses flow-induced Ca(2+) response.

  11. A disposable microfluidic biochip with on-chip molecularly imprinted biosensors for optical detection of anesthetic propofol.

    PubMed

    Hong, Chien-Chong; Chang, Po-Hsiang; Lin, Chih-Chung; Hong, Chian-Lang

    2010-05-15

    This paper presents a disposable microfluidic biochip with on-chip molecularly imprinted biosensors for optical detection of anesthetic propofol. So far, the methods to detect anesthetic propofol in hospitals are liquid chromatography (LC), high-performance liquid chromatography (HPLC), and gas chromatography-mass spectroscopy (GC-MS). These conventional instruments are bulky, expensive, and not ease of access. In this work, a novel plastic microfluidic biochip with on-chip anesthetic biosensor has been developed and characterized for rapid detection of anesthetic propofol. The template-molecule imprinted polymers were integrated into microfluidic biochips to be used for detecting anesthetic propofol optically at 655 nm wavelength after the reaction of propofol with color reagent. Experimental results show that the sensitivity of the microfluidic biochip with on-chip molecularly imprinted polymers (MIPs) biosensor is 6.47 mV/(ppm mm(2)). The specific binding of MIP to non-imprinted polymer (NIP) is up to 456%. And the detection limit of the microsystem is 0.25 ppm with a linear detection range from 0.25 to 10 ppm. The disposable microfluidic biochip with on-chip anesthetic biosensor using molecularly imprinted polymers presented in this work showed excellent performance in separation and sensing of anesthetic propofol molecules. While compared to large-scale conventional instruments, the developed microfluidic biochips with on-chip MIP biosensors have the advantages of compact size, high sensitivity, high selectivity, low cost, and fast response.

  12. Fabrication of Poly(methyl Methacrylate) microfluidic chips by redox-initiated polymerization

    SciTech Connect

    Chen, Jiang; Lin, Yuehe; Chen, Gang

    2007-08-16

    In this report, a method based on the redox-initiated polymerization of methyl methacrylate (MMA) has been developed for the rapid fabrication of PMMA microfluidic chips.The new fabrication approach obviates the need for special equipment and significantly simplifies the process of fabricating microdevices. The attractive performance of the novel PMMA microchips has been demonstrated in connection with contactless conductivity detection for the separation and detection of ionic species.

  13. Chemiluminescence generation and detection in a capillary-driven microfluidic chip

    NASA Astrophysics Data System (ADS)

    Ramon, Charlotte; Temiz, Yuksel; Delamarche, Emmanuel

    2017-02-01

    The use of microfluidic technology represents a strong opportunity for providing sensitive, low-cost and rapid diagnosis at the point-of-care and such a technology might therefore support better, faster and more efficient diagnosis and treatment of patients at home and in healthcare settings both in developed and developing countries. In this work, we consider luminescence-based assays as an alternative to well-established fluorescence-based systems because luminescence does not require a light source or expensive optical components and is therefore a promising detection method for point-of-care applications. Here, we show a proof-of-concept of chemiluminescence (CL) generation and detection in a capillary-driven microfluidic chip for potential immunoassay applications. We employed a commercial acridan-based reaction, which is catalyzed by horseradish peroxidase (HRP). We investigated CL generation under flow conditions using a simplified immunoassay model where HRP is used instead of the complete sandwich immunocomplex. First, CL signals were generated in a capillary microfluidic chip by immobilizing HRP on a polydimethylsiloxane (PDMS) sealing layer using stencil deposition and flowing CL substrate through the hydrophilic channels. CL signals were detected using a compact (only 5×5×2.5 cm3) and custom-designed scanner, which was assembled for less than $30 and comprised a 128×1 photodiode array, a mini stepper motor, an Arduino microcontroller, and a 3D-printed housing. In addition, microfluidic chips having specific 30-μm-deep structures were fabricated and used to immobilize ensembles of 4.50 μm beads functionalized with HRP so as to generate high CL signals from capillary-driven chips.

  14. Photonic crystal fiber integrated microfluidic chip for highly sensitive real-time chemical sensing

    NASA Astrophysics Data System (ADS)

    Yong, Derrick Z. Y.; Yu, Xia; Chan, Chi C.; Zhang, Ying; Shum, Ping

    2011-05-01

    Photonic crystal fibers (PCFs), although a highly effective platform for sensing, encounter difficulties with coupling as well as infiltration and evacuation. A PCF integrated microfluidic chip has therefore been fabricated to demonstrate improved coupling for real-time chemical sensing. Furthermore, an extremely sensitive dip-shifting analysis was employed for the detection regime. Results eventually demonstrated its notable sensitivity and a refractive index resolution of 10-7 RIU, rendering it suitable for utilization in highly sensitive sensing applications.

  15. Integrated optofluidic-microfluidic twin channels: toward diverse application of lab-on-a-chip systems

    PubMed Central

    Lv, Chao; Xia, Hong; Guan, Wei; Sun, Yun-Lu; Tian, Zhen-Nan; Jiang, Tong; Wang, Ying-Shuai; Zhang, Yong-Lai; Chen, Qi-Dai; Ariga, Katsuhiko; Yu, Yu-De; Sun, Hong-Bo

    2016-01-01

    Optofluidics, which integrates microfluidics and micro-optical components, is crucial for optical sensing, fluorescence analysis, and cell detection. However, the realization of an integrated system from optofluidic manipulation and a microfluidic channel is often hampered by the lack of a universal substrate for achieving monolithic integration. In this study, we report on an integrated optofluidic-microfluidic twin channels chip fabricated by one-time exposure photolithography, in which the twin microchannels on both surfaces of the substrate were exactly aligned in the vertical direction. The twin microchannels can be controlled independently, meaning that fluids could flow through both microchannels simultaneously without interfering with each other. As representative examples, a tunable hydrogel microlens was integrated into the optofluidic channel by femtosecond laser direct writing, which responds to the salt solution concentration and could be used to detect the microstructure at different depths. The integration of such optofluidic and microfluidic channels provides an opportunity to apply optofluidic detection practically and may lead to great promise for the integration and miniaturization of Lab-on-a-Chip systems. PMID:26823292

  16. Integrated optofluidic-microfluidic twin channels: toward diverse application of lab-on-a-chip systems

    NASA Astrophysics Data System (ADS)

    Lv, Chao; Xia, Hong; Guan, Wei; Sun, Yun-Lu; Tian, Zhen-Nan; Jiang, Tong; Wang, Ying-Shuai; Zhang, Yong-Lai; Chen, Qi-Dai; Ariga, Katsuhiko; Yu, Yu-De; Sun, Hong-Bo

    2016-01-01

    Optofluidics, which integrates microfluidics and micro-optical components, is crucial for optical sensing, fluorescence analysis, and cell detection. However, the realization of an integrated system from optofluidic manipulation and a microfluidic channel is often hampered by the lack of a universal substrate for achieving monolithic integration. In this study, we report on an integrated optofluidic-microfluidic twin channels chip fabricated by one-time exposure photolithography, in which the twin microchannels on both surfaces of the substrate were exactly aligned in the vertical direction. The twin microchannels can be controlled independently, meaning that fluids could flow through both microchannels simultaneously without interfering with each other. As representative examples, a tunable hydrogel microlens was integrated into the optofluidic channel by femtosecond laser direct writing, which responds to the salt solution concentration and could be used to detect the microstructure at different depths. The integration of such optofluidic and microfluidic channels provides an opportunity to apply optofluidic detection practically and may lead to great promise for the integration and miniaturization of Lab-on-a-Chip systems.

  17. Integrated optofluidic-microfluidic twin channels: toward diverse application of lab-on-a-chip systems.

    PubMed

    Lv, Chao; Xia, Hong; Guan, Wei; Sun, Yun-Lu; Tian, Zhen-Nan; Jiang, Tong; Wang, Ying-Shuai; Zhang, Yong-Lai; Chen, Qi-Dai; Ariga, Katsuhiko; Yu, Yu-De; Sun, Hong-Bo

    2016-01-29

    Optofluidics, which integrates microfluidics and micro-optical components, is crucial for optical sensing, fluorescence analysis, and cell detection. However, the realization of an integrated system from optofluidic manipulation and a microfluidic channel is often hampered by the lack of a universal substrate for achieving monolithic integration. In this study, we report on an integrated optofluidic-microfluidic twin channels chip fabricated by one-time exposure photolithography, in which the twin microchannels on both surfaces of the substrate were exactly aligned in the vertical direction. The twin microchannels can be controlled independently, meaning that fluids could flow through both microchannels simultaneously without interfering with each other. As representative examples, a tunable hydrogel microlens was integrated into the optofluidic channel by femtosecond laser direct writing, which responds to the salt solution concentration and could be used to detect the microstructure at different depths. The integration of such optofluidic and microfluidic channels provides an opportunity to apply optofluidic detection practically and may lead to great promise for the integration and miniaturization of Lab-on-a-Chip systems.

  18. Continuous isolation of monocytes using a magnetophoretic-based microfluidic Chip.

    PubMed

    Darabi, Jeff; Guo, Chuan

    2016-10-01

    Monocytes play an important role in the immune system and are responsible for phagocytizing and degrading foreign microorganisms in the body. The isolation of monocytes is important in various immunological applications such as in-vitro culture of dendritic cells. We present a magnetophoretic-based microfluidic chip for rapid isolation of highly purified, untouched monocytes from human blood by a negative selection method. This bioseparation platform integrates several unique features into a microfluidic device, including locally engineered magnetic field gradients and a continuous flow with a buffer switching scheme to improve the performance of the cell separation process. The results indicate high monocyte purity and recovery performances at a volumetric flow rate that is nearly an order of magnitude larger than comparable microfluidic devices reported in literature. In addition, a comprehensive 2-D computational modeling is performed to determine the cell trajectory and trapping length within the microfluidic chip. Furthermore, the effects of channel height, substrate thickness, cell size, number of beads per cell, and sample flow rate on the cell separation performance are studied.

  19. A novel microfluidic chip for assessing dynamic adhesion behavior of cell-targeting microbubbles.

    PubMed

    Yan, Fei; Li, Xiang; Jiang, Chunxiang; Jin, Qiaofeng; Zhang, Zidong; Shandas, Robin; Wu, Junru; Liu, Xin; Zheng, Hairong

    2014-01-01

    The primary aim of this study was to develop a microfluidic chip to study the dynamic adhesion behavior of cell-targeted microbubbles. The microfluidic device is composed of polydimethylsiloxane and is fabricated using the soft lithography technique. Each chamber of the microfluidic chip comprises eight U-shaped microsieves, by which various flow velocity distributions are generated. LyP-1-conjugated microbubbles were prepared by coating the surface of the phospholipid shell of microbubbles with LyP-1 peptides via biotin-avidin linkage. Under static conditions, the resulting targeted microbubbles are able to bind onto the surface of cells on incubation with breast cancer cells. Under dynamic fluid conditions, the cell targeting efficiency of the microbubbles was assessed at various flow velocity distributions in a chamber. Accumulation of targeted microbubbles was strongly influenced by flow velocity. Better retention of targeted microbubbles on cell surfaces was achieved at low mean flow velocities (<0.03 cm/s), in agreement with our computer simulation results. In conclusion, our results indicate that the microfluidic system is a useful platform for studying the microbubble-cell adhesive interaction. Copyright © 2014 World Federation for Ultrasound in Medicine & Biology. All rights reserved.

  20. A review of digital microfluidics as portable platforms for lab-on a-chip applications.

    PubMed

    Samiei, Ehsan; Tabrizian, Maryam; Hoorfar, Mina

    2016-07-07

    Following the development of microfluidic systems, there has been a high tendency towards developing lab-on-a-chip devices for biochemical applications. A great deal of effort has been devoted to improve and advance these devices with the goal of performing complete sets of biochemical assays on the device and possibly developing portable platforms for point of care applications. Among the different microfluidic systems used for such a purpose, digital microfluidics (DMF) shows high flexibility and capability of performing multiplex and parallel biochemical operations, and hence, has been considered as a suitable candidate for lab-on-a-chip applications. In this review, we discuss the most recent advances in the DMF platforms, and evaluate the feasibility of developing multifunctional packages for performing complete sets of processes of biochemical assays, particularly for point-of-care applications. The progress in the development of DMF systems is reviewed from eight different aspects, including device fabrication, basic fluidic operations, automation, manipulation of biological samples, advanced operations, detection, biological applications, and finally, packaging and portability of the DMF devices. Success in developing the lab-on-a-chip DMF devices will be concluded based on the advances achieved in each of these aspects.

  1. Refolding of difficult-to-fold proteins by a gradual decrease of denaturant using microfluidic chips.

    PubMed

    Yamaguchi, Hiroshi; Miyazaki, Masaya; Briones-Nagata, Maria Portia; Maeda, Hideaki

    2010-06-01

    Protein refolding is an important process to obtain active recombinant proteins from inclusion bodies (protein aggregates). However, the conventional refolding method of dialysis or dilution is a time consuming procedure and often, recovering yields of active proteins are low. In this study, we used controllable diffusion through laminar flow in microchannels to control the denaturant concentration. The performance of the designed microfluidic chips was evaluated by the refolding of difficult-to-fold proteins (citrate synthase and the zeta-associated protein 70-kDa protein kinase domain). We demonstrated this by varying the flow rates of the diluting buffer stream(s) and multi-junctions which could control the different flow rate ratios of the buffer stream(s) and the denatured protein stream. By this strategy, we were able to improve the efficiency of protein refolding. Our method achieved refolding within a short period of time at room temperature without the need of any small molecules or chaperone proteins. Moreover, the efficiency of protein refolding by microfluidic chip was found higher than that prepared by dialysis or dilution. These results suggest that microfluidic chips employing this strategy may provide miniaturized tools for rapid and efficient recovery of active proteins from inclusion bodies.

  2. Absolute quantification of DNA methylation using microfluidic chip-based digital PCR.

    PubMed

    Wu, Zhenhua; Bai, Yanan; Cheng, Zule; Liu, Fangming; Wang, Ping; Yang, Dawei; Li, Gang; Jin, Qinghui; Mao, Hongju; Zhao, Jianlong

    2017-10-15

    Hypermethylation of CpG islands in the promoter region of many tumor suppressor genes downregulates their expression and in a result promotes tumorigenesis. Therefore, detection of DNA methylation status is a convenient diagnostic tool for cancer detection. Here, we reported a novel method for the integrative detection of methylation by the microfluidic chip-based digital PCR. This method relies on methylation-sensitive restriction enzyme HpaII, which cleaves the unmethylated DNA strands while keeping the methylated ones intact. After HpaII treatment, the DNA methylation level is determined quantitatively by the microfluidic chip-based digital PCR with the lower limit of detection equal to 0.52%. To validate the applicability of this method, promoter methylation of two tumor suppressor genes (PCDHGB6 and HOXA9) was tested in 10 samples of early stage lung adenocarcinoma and their adjacent non-tumorous tissues. The consistency was observed in the analysis of these samples using our method and a conventional bisulfite pyrosequencing. Combining high sensitivity and low cost, the microfluidic chip-based digital PCR method might provide a promising alternative for the detection of DNA methylation and early diagnosis of epigenetics-related diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Capillary-driven surface-enhanced Raman scattering (SERS)-based microfluidic chip for abrin detection

    NASA Astrophysics Data System (ADS)

    Yang, Hao; Deng, Min; Ga, Shan; Chen, Shouhui; Kang, Lin; Wang, Junhong; Xin, Wenwen; Zhang, Tao; You, Zherong; An, Yuan; Wang, Jinglin; Cui, Daxiang

    2014-03-01

    Herein, we firstly demonstrate the design and the proof-of-concept use of a capillary-driven surface-enhanced Raman scattering (SERS)-based microfluidic chip for abrin detection. The micropillar array substrate was etched and coated with a gold film by microelectromechanical systems (MEMS) process to integrate into a lateral flow test strip. The detection of abrin solutions of various concentrations was performed by the as-prepared microfluidic chip. It was shown that the correlation between the abrin concentration and SERS signal was found to be linear within the range of 0.1 ng/mL to 1 μg/mL with a limit of detection of 0.1 ng/mL. Our microfluidic chip design enhanced the operability of SERS-based immunodiagnostic techniques, significantly reducing the complication and cost of preparation as compared to previous SERS-based works. Meanwhile, this design proved the superiority to conventional lateral flow test strips in respect of both sensitivity and quantitation and showed great potential in the diagnosis and treatment for abrin poisoning as well as on-site screening of abrin-spiked materials.

  4. Parallel temperature-dependent microrheological measurements in a microfluidic chip.

    PubMed

    Josephson, Lilian Lam; Galush, William J; Furst, Eric M

    2016-07-01

    Microfluidic stickers are used as a sample environment to measure the microrheology of monoclonal antibody (mAb) protein solutions. A Peltier-based microscope stage is implemented and validated, and is capable of controlling the sample temperature over the range 0.9-40 °C. The design accounts for heat transfer to and from the objective, controls the sample environment humidity to mitigate condensation, and provides adequate damping to reduce vibration from the cooling system. A concentrated sucrose solution is used as a standard sample to provide an in situ temperature measurement by the Stokes-Einstein-Sutherland relation. By combining microfluidic stickers and microrheology, 72 temperature-concentration viscosity measurements of mAb solutions can be made in 1 day, a significant increase in throughput over conventional rheometry.

  5. Scattering detection using a photonic-microfluidic integrated device with on-chip collection capabilities.

    PubMed

    Watts, Benjamin R; Zhang, Zhiyi; Xu, Chang Qing; Cao, Xudong; Lin, Min

    2014-02-01

    SU-8-based photonic-microfluidic integrated devices with on-chip beam shaping and collection capabilities were demonstrated in a scattering detection and counting application. Through the proper deployment of the tailored beam geometries via the on-chip excitation optics, excellent CV values were measured for 1, 2, and 5 μm blank beads, 16.4, 11.0, and 12.5%, respectively, coupled with a simple free-space optical detection scheme. The performance of these devices was found dependent on the combination of on-chip, lens-shaped beam geometry and bead size. While very low CVs were obtained when the combination was ideal, a nonideal combination could still result in acceptable CVs for flow cytometry; the reliability was confirmed via devices being able to resolve separate populations of 2.0 and 5.0 μm beads from their mixture with low CV values of 15.9 and 18.5%, respectively. On-chip collection using integrated on-chip optical waveguides was shown to be very reliable in comparison with a free-space collection scheme, yielding a coincident rate of 94.2%. A CV as low as 19.2% was obtained from the on-chip excitation and collection of 5 μm beads when the on-chip lens-shaped beam had a 6.0-μm beam waist.

  6. Microfluidic chip-based analytical system for rapid screening of photocatalysts.

    PubMed

    Zhang, Hao; Wang, Jing-Jing; Fan, Jie; Fang, Qun

    2013-11-15

    A simple and efficient microfluidic chip-based analytical system for rapid screening of photocatalysts was developed. The catalyst screening system consisted of a microchip with multiple channels for parallel reactions, a UV light source, and a CCD camera-based photometric detection system for monitoring the photocatalytic reaction. A novel microfluidic introduction method for loading particle samples into chip microchannels was established using dry sample powders and wedge-structure channel design. With this method, multiple different photocatalyst samples could be quickly introduced into the microchip with good reproducibility without the need of additional pumps or valves. We applied the present system in the rapid screening of doping TiO2 photocatalysts in terms of their activity for methylene blue (MB) degradation under UV light irradiation. Ten parallel photocatalyst screening reactions were achieved within 15 min in the multi-channel chip. We also examined nine element doped TiO2 materials to investigate the doping effects of different elements on TiO2. Compared with conventional systems, the photocatalyst consumption (0.1mg) in the present system was significantly reduced at least 100 times. High reaction rate in chip microreactors was obtained with an increase of two orders of magnitude over bulk reactors. The miniaturization of the photocatalytic reaction on the microchip significantly improves the reaction rates, reduces the sample and reagent consumptions, and increases the throughput of screening for multiple catalyst samples in parallel. The present work provides a novel application for microfluidic chip-based analytical systems, as well as a rapid, highly-efficient and low-consumption method for screening of photocatalysts.

  7. Recent Results of the Investigation of a Microfluidic Sampling Chip and Sampling System for Hot Cell Aqueous Processing Streams

    SciTech Connect

    Julia Tripp; Jack Law; Tara Smith

    2013-10-01

    A Fuel Cycle Research and Development project has investigated an innovative sampling method that could evolve into the next generation sampling and analysis system for metallic elements present in aqueous processing streams. Initially sampling technologies were evaluated and microfluidics sampling chip technology was selected and tested. A conceptual design for a fully automated microcapillary-based system was completed and a robotic automated sampling system was fabricated. The mechanical and sampling operation of the completed sampling system was investigated. In addition, the production of a less expensive, mass produced sampling chip was investigated to avoid chip reuse thus increasing sampling reproducibility/accuracy. The microfluidic-based robotic sampling system’s mechanical elements were tested to ensure analytical reproducibility and the optimum robotic handling of microfluidic sampling chips.

  8. Capillary-driven microfluidic chips with evaporation-induced flow control and dielectrophoretic microbead trapping

    NASA Astrophysics Data System (ADS)

    Temiz, Yuksel; Skorucak, Jelena; Delamarche, Emmanuel

    2014-03-01

    This work reports our efforts on developing simple-to-use microfluidic devices for point-of-care diagnostic applications with recent extensions that include the trapping of microbeads using dielectrophoresis (DEP) and the modulation of capillary-driven flow using integrated microheaters. DEP serves the purpose of trapping microbeads coated with receptors and analytes for detection of a fluorescent signal. The microheater is actuated once the chip is filled by capillarity, creating an evaporation-induced flow tuned according to assay conditions. The chips are composed of a glass substrate patterned with 50-nm-thick Pd electrodes and microfluidic structures made using a 20-μm-thick dry-film resist (DFR). Chips are covered/sealed by low-temperature (50 °C) lamination of a 50-μm-thick DFR layer having excellent optical and mechanical properties. To separate cleaned and sealed chips from the wafer, we used an effective chip singulation technique that we informally call the "chip-olate" process. In the experimental section, we first studied dielectrophoretic trapping of 10 μm beads for flow rates ranging from 80 pL s-1 to 2.5 nL s-1 and that are generated by an external syringe pump. Then, we characterized the embedded microheater in DFR-covered chips. Flow rates as high as 8 nL s-1 were generated by evaporation-induced flow when the heater was biased by 10 V, corresponding to 270 mW power. Finally, DEP-based trapping and fluorescent detection of functionalized beads were demonstrated as the flow was generated by the combination of capillary filling and evaporation-induced flow.

  9. Development of a microfluidic "click chip" incorporating an immobilized Cu(I) catalyst.

    PubMed

    Li, Hairong; Whittenberg, Joseph J; Zhou, Haiying; Ranganathan, David; Desai, Amit V; Koziol, Jan; Zeng, Dexing; Kenis, Paul J A; Reichert, David E

    2015-01-01

    We have developed a microfluidic "click chip" incorporating an immobilized Cu(I) catalyst for click reactions. The microfluidic device was fabricated from polydimethylsiloxane (PDMS) bonded to glass and featured ~14,400 posts on the surface to improve catalyst immobilization. This design increased the immobilization efficiency and reduces the reagents' diffusion time to active catalyst site. The device also incorporates five reservoirs to increase the reaction volume with minimal hydrodynamic pressure drop across the device. A novel water-soluble tris-(benzyltriazolylmethyl)amine (TBTA) derivative capable of stabilizing Cu(I), ligand 2, was synthesized and successfully immobilized on the chip surface. The catalyst immobilized chip surface was characterized by X-ray photoelectron spectroscopy (XPS). The immobilization efficiency was evaluated via radiotracer methods: the immobilized Cu(I) was measured as 1136±272 nmol and the surface immobilized Cu(I) density was 81±20 nmol cm(-2). The active Cu(I)-ligand 2 could be regenerated up to five times without losing any catalyst efficiency. The "click" reaction of Flu568-azide and propargylamine was studied on chip for proof-of-principle. The on-chip reaction yields were ca. 82% with a 50 min reaction time or ca. 55% with a 15 min period at 37 °C, which was higher than those obtained in the conventional reaction. The on-chip "click" reaction involving a biomolecule, cyclo(RGDfK) peptide was also studied and demonstrated a conversion yield of ca. 98%. These encouraging results show promise on the application of the Cu(I) catalyst immobilized "click chip" for the development of biomolecule based imaging agents.

  10. Single-layer planar on-chip flow cytometer using microfluidic drifting based three-dimensional (3D) hydrodynamic focusing.

    PubMed

    Mao, Xiaole; Lin, Sz-Chin Steven; Dong, Cheng; Huang, Tony Jun

    2009-06-07

    In this work, we demonstrate an on-chip microfluidic flow cytometry system based on a three-dimensional (3D) hydrodynamic focusing technique, microfluidic drifting. By inducing Dean flow in a curved microfluidic channel, microfluidic drifting can be used to hydrodynamically focus cells or particles in the vertical direction and enables the 3D hydrodynamic focusing in a single-layer planar microfluidic device. Through theoretical calculation, numerical simulation, and experimental characterization, we found that the microfluidic drifting technique can be effectively applied to three-dimensionally focus microparticles with density and size equivalent to those of human CD4+ T lymphocytes. In addition, we developed a flow cytometry platform by integrating the 3D focusing device with a laser-induced fluorescence (LIF) detection system. The system was shown to provide effective high-throughput flow cytometry measurements at a rate of greater than 1700 cells s(-1).

  11. Self-powered integrated microfluidic point-of-care low-cost enabling (SIMPLE) chip

    PubMed Central

    Yeh, Erh-Chia; Fu, Chi-Cheng; Hu, Lucy; Thakur, Rohan; Feng, Jeffrey; Lee, Luke P.

    2017-01-01

    Portable, low-cost, and quantitative nucleic acid detection is desirable for point-of-care diagnostics; however, current polymerase chain reaction testing often requires time-consuming multiple steps and costly equipment. We report an integrated microfluidic diagnostic device capable of on-site quantitative nucleic acid detection directly from the blood without separate sample preparation steps. First, we prepatterned the amplification initiator [magnesium acetate (MgOAc)] on the chip to enable digital nucleic acid amplification. Second, a simplified sample preparation step is demonstrated, where the plasma is separated autonomously into 224 microwells (100 nl per well) without any hemolysis. Furthermore, self-powered microfluidic pumping without any external pumps, controllers, or power sources is accomplished by an integrated vacuum battery on the chip. This simple chip allows rapid quantitative digital nucleic acid detection directly from human blood samples (10 to 105 copies of methicillin-resistant Staphylococcus aureus DNA per microliter, ~30 min, via isothermal recombinase polymerase amplification). These autonomous, portable, lab-on-chip technologies provide promising foundations for future low-cost molecular diagnostic assays. PMID:28345028

  12. Disposable on-chip microfluidic system for buccal cell lysis, DNA purification, and polymerase chain reaction.

    PubMed

    Cho, Woong; Maeng, Joon-Ho; Ahn, Yoomin; Hwang, Seung Yong

    2013-09-01

    This paper reports the development of a disposable, integrated biochip for DNA sample preparation and PCR. The hybrid biochip (25 × 45 mm) is composed of a disposable PDMS layer with a microchannel chamber and reusable glass substrate integrated with a microheater and thermal microsensor. Lysis, purification, and PCR can be performed sequentially on this microfluidic device. Cell lysis is achieved by heat and purification is performed by mechanical filtration. Passive check valves are integrated to enable sample preparation and PCR in a fixed sequence. Reactor temperature is needed to lysis and PCR reaction is controlled within ±1°C by PID controller of LabVIEW software. Buccal epithelial cell lysis, DNA purification, and SY158 gene PCR amplification were successfully performed on this novel chip. Our experiments confirm that the entire process, except the off-chip gel electrophoresis, requires only approximately 1 h for completion. This disposable microfluidic chip for sample preparation and PCR can be easily united with other technologies to realize a fully integrated DNA chip. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. An integrated microfluidic chip enabling control and spatially resolved monitoring of temperature in micro flow reactors.

    PubMed

    Hoera, Christian; Ohla, Stefan; Shu, Zhe; Beckert, Erik; Nagl, Stefan; Belder, Detlev

    2015-01-01

    A strength of microfluidic chip laboratories is the rapid heat transfer that, in principle, enables a very homogeneous temperature distribution in chemical processes. In order to exploit this potential, we present an integrated chip system where the temperature is precisely controlled and monitored at the microfluidic channel level. This is realized by integration of a luminescent temperature sensor layer into the fluidic structure together with inkjet-printed micro heating elements. This allows steering of the temperature at the microchannel level and monitoring of the reaction progress simultaneously. A fabrication procedure is presented that allows for straightforward integration of thin polymer layers with optical sensing functionality in microchannels of glass-polydimethylsiloxane (PDMS) chips of only 150 μm width and 29 μm height. Sensor layers consisting of polyacrylonitrile and a temperature-sensitive ruthenium tris-phenanthroline probe with film thicknesses of about 0.5 to 6 μm were generated by combining blade coating and abrasion techniques. Optimal coating procedures were developed and evaluated. The chip-integrated sensor layers were calibrated and investigated with respect to stability, reproducibility, and response times. These microchips allowed observation of temperature in a wide range with a signal change of around 1.6 % per K and a maximum resolution of around 0.07 K. The device is employed to study temperature-controlled continuous micro flow reactions. This is demonstrated exemplarily for the tryptic cleavage of coumarin-modified peptides via fluorescence detection.

  14. Integration of programmable microfluidics and on-chip fluorescence detection for biosensing applications

    PubMed Central

    Parks, J. W.; Olson, M. A.; Kim, J.; Ozcelik, D.; Cai, H.; Carrion, R.; Patterson, J. L.; Mathies, R. A.; Hawkins, A. R.; Schmidt, H.

    2014-01-01

    We describe the integration of an actively controlled programmable microfluidic sample processor with on-chip optical fluorescence detection to create a single, hybrid sensor system. An array of lifting gate microvalves (automaton) is fabricated with soft lithography, which is reconfigurably joined to a liquid-core, anti-resonant reflecting optical waveguide (ARROW) silicon chip fabricated with conventional microfabrication. In the automaton, various sample handling steps such as mixing, transporting, splitting, isolating, and storing are achieved rapidly and precisely to detect viral nucleic acid targets, while the optofluidic chip provides single particle detection sensitivity using integrated optics. Specifically, an assay for detection of viral nucleic acid targets is implemented. Labeled target nucleic acids are first captured and isolated on magnetic microbeads in the automaton, followed by optical detection of single beads on the ARROW chip. The combination of automated microfluidic sample preparation and highly sensitive optical detection opens possibilities for portable instruments for point-of-use analysis of minute, low concentration biological samples. PMID:25584111

  15. Integration of programmable microfluidics and on-chip fluorescence detection for biosensing applications.

    PubMed

    Parks, J W; Olson, M A; Kim, J; Ozcelik, D; Cai, H; Carrion, R; Patterson, J L; Mathies, R A; Hawkins, A R; Schmidt, H

    2014-09-01

    We describe the integration of an actively controlled programmable microfluidic sample processor with on-chip optical fluorescence detection to create a single, hybrid sensor system. An array of lifting gate microvalves (automaton) is fabricated with soft lithography, which is reconfigurably joined to a liquid-core, anti-resonant reflecting optical waveguide (ARROW) silicon chip fabricated with conventional microfabrication. In the automaton, various sample handling steps such as mixing, transporting, splitting, isolating, and storing are achieved rapidly and precisely to detect viral nucleic acid targets, while the optofluidic chip provides single particle detection sensitivity using integrated optics. Specifically, an assay for detection of viral nucleic acid targets is implemented. Labeled target nucleic acids are first captured and isolated on magnetic microbeads in the automaton, followed by optical detection of single beads on the ARROW chip. The combination of automated microfluidic sample preparation and highly sensitive optical detection opens possibilities for portable instruments for point-of-use analysis of minute, low concentration biological samples.

  16. Temperature regulation during ultrasonic manipulation for long-term cell handling in a microfluidic chip

    NASA Astrophysics Data System (ADS)

    Svennebring, J.; Manneberg, O.; Wiklund, M.

    2007-12-01

    We demonstrate simultaneous micromanipulation and temperature regulation by the use of ultrasonic standing wave technology in a microfluidic chip. The system is based on a microfabricated silicon structure sandwiched between two glass layers, and an external ultrasonic transducer using a refractive wedge placed on top of the chip for efficient coupling of ultrasound into the microchannel. The chip is fully transparent and compatible with any kind of high-resolution optical microscopy. The temperature regulation method uses calibration data of the temperature increase due to the ultrasonic actuation for determining the temperature of the surrounding air and microscope table, controlled by a warm-air heating unit and a heatable mounting frame. The heating methods are independent of each other, resulting in a flexible choice of ultrasonic actuation voltage and flow rate for different cell and particle manipulation purposes. Our results indicate that it is possible to perform stable temperature regulation with an accuracy of the order of ±0.1 °C around any physiologically relevant temperature (e.g., 37 °C) with high temporal stability and repeatability. The purpose is to use ultrasound for long-term cell and/or particle handling in a microfluidic chip while controlling and maintaining the biocompatibility of the system.

  17. A microfluidic chip for direct and rapid trapping of white blood cells from whole blood

    PubMed Central

    Chen, Jingdong; Chen, Di; Yuan, Tao; Xie, Yao; Chen, Xiang

    2013-01-01

    Blood analysis plays a major role in medical and science applications and white blood cells (WBCs) are an important target of analysis. We proposed an integrated microfluidic chip for direct and rapid trapping WBCs from whole blood. The microfluidic chip consists of two basic functional units: a winding channel to mix and arrays of two-layer trapping structures to trap WBCs. Red blood cells (RBCs) were eliminated through moving the winding channel and then WBCs were trapped by the arrays of trapping structures. We fabricated the PDMS (polydimethylsiloxane) chip using soft lithography and determined the critical flow velocities of tartrazine and brilliant blue water mixing and whole blood and red blood cell lysis buffer mixing in the winding channel. They are 0.25 μl/min and 0.05 μl/min, respectively. The critical flow velocity of the whole blood and red blood cell lysis buffer is lower due to larger volume of the RBCs and higher kinematic viscosity of the whole blood. The time taken for complete lysis of whole blood was about 85 s under the flow velocity 0.05 μl/min. The RBCs were lysed completely by mixing and the WBCs were trapped by the trapping structures. The chip trapped about 2.0 × 103 from 3.3 × 103 WBCs. PMID:24404026

  18. A microfluidic chip for direct and rapid trapping of white blood cells from whole blood.

    PubMed

    Chen, Jingdong; Chen, Di; Yuan, Tao; Xie, Yao; Chen, Xiang

    2013-01-01

    Blood analysis plays a major role in medical and science applications and white blood cells (WBCs) are an important target of analysis. We proposed an integrated microfluidic chip for direct and rapid trapping WBCs from whole blood. The microfluidic chip consists of two basic functional units: a winding channel to mix and arrays of two-layer trapping structures to trap WBCs. Red blood cells (RBCs) were eliminated through moving the winding channel and then WBCs were trapped by the arrays of trapping structures. We fabricated the PDMS (polydimethylsiloxane) chip using soft lithography and determined the critical flow velocities of tartrazine and brilliant blue water mixing and whole blood and red blood cell lysis buffer mixing in the winding channel. They are 0.25 μl/min and 0.05 μl/min, respectively. The critical flow velocity of the whole blood and red blood cell lysis buffer is lower due to larger volume of the RBCs and higher kinematic viscosity of the whole blood. The time taken for complete lysis of whole blood was about 85 s under the flow velocity 0.05 μl/min. The RBCs were lysed completely by mixing and the WBCs were trapped by the trapping structures. The chip trapped about 2.0 × 10(3) from 3.3 × 10(3) WBCs.

  19. Comparison of Chip Inlet Geometry in Microfluidic Devices for Cell Studies.

    PubMed

    Sun, Yung-Shin

    2016-06-15

    Micro-fabricated devices integrated with fluidic components provide an in vitro platform for cell studies best mimicking the in vivo micro-environment. These devices are capable of creating precise and controllable surroundings of pH value, temperature, salt concentration, and other physical or chemical stimuli. Various cell studies such as chemotaxis and electrotaxis can be performed by using such devices. Moreover, microfluidic chips are designed and fabricated for applications in cell separations such as circulating tumor cell (CTC) chips. Usually, there are two most commonly used inlets in connecting the microfluidic chip to sample/reagent loading tubes: the vertical (top-loading) inlet and the parallel (in-line) inlet. Designing this macro-to-micro interface is believed to play an important role in device performance. In this study, by using the commercial COMSOL Multiphysics software, we compared the cell capture behavior in microfluidic devices with different inlet types and sample flow velocities. Three different inlets were constructed: the vertical inlet, the parallel inlet, and the vertically parallel inlet. We investigated the velocity field, the flow streamline, the cell capture rate, and the laminar shear stress in these inlets. It was concluded that the inlet should be designed depending on the experimental purpose, i.e., one wants to maximize or minimize cell capture. Also, although increasing the flow velocity could reduce cell sedimentation, too high shear stresses are thought harmful to cells. Our findings indicate that the inlet design and flow velocity are crucial and should be well considered in fabricating microfluidic devices for cell studies.

  20. Rapid determination of cell mass and density using digitally controlled electric field in a microfluidic chip.

    PubMed

    Zhao, Yuliang; Lai, Hok Sum Sam; Zhang, Guanglie; Lee, Gwo-Bin; Li, Wen Jung

    2014-11-21

    The density of a single cell is a fundamental property of cells. Cells in the same cycle phase have similar volume, but the differences in their mass and density could elucidate each cell's physiological state. Here we report a novel technique to rapidly measure the density and mass of a single cell using an optically induced electrokinetics (OEK) microfluidic platform. Presently, single cellular mass and density measurement devices require a complicated fabrication process and their output is not scalable, i.e., it is extremely difficult to measure the mass and density of a large quantity of cells rapidly. The technique reported here operates on a principle combining sedimentation theory, computer vision, and microparticle manipulation techniques in an OEK microfluidic platform. We will show in this paper that this technique enables the measurement of single-cell volume, density, and mass rapidly and accurately in a repeatable manner. The technique is also scalable - it allows simultaneous measurement of volume, density, and mass of multiple cells. Essentially, a simple time-controlled projected light pattern is used to illuminate the selected area on the OEK microfluidic chip that contains cells to lift the cells to a particular height above the chip's surface. Then, the cells are allowed to "free fall" to the chip's surface, with competing buoyancy, gravitational, and fluidic drag forces acting on the cells. By using a computer vision algorithm to accurately track the motion of the cells and then relate the cells' motion trajectory to sedimentation theory, the volume, mass, and density of each cell can be rapidly determined. A theoretical model of micro-sized spheres settling towards an infinite plane in a microfluidic environment is first derived and validated experimentally using standard micropolystyrene beads to demonstrate the viability and accuracy of this new technique. Next, we show that the yeast cell volume, mass, and density could be rapidly

  1. Imaging through scattering microfluidic channels by digital holography for information recovery in lab on chip.

    PubMed

    Bianco, V; Paturzo, M; Gennari, O; Finizio, A; Ferraro, P

    2013-10-07

    We tackle the problem of information recovery and imaging through scattering microfluidic chips by means of digital holography (DH). In many cases the chip can become opalescent due to residual deposits settling down the inner channel faces, biofilm formation, scattering particle uptake by the channel cladding or its damaging by corrosive substances, or even by condensing effect on the exterior channels walls. In these cases white-light imaging is severely degraded and no information is obtainable at all about the flowing samples. Here we investigate the problem of counting and estimating velocity of cells flowing inside a scattering chip. Moreover we propose and test a method based on the recording of multiple digital holograms to retrieve improved phase-contrast images despite the strong scattering effect. This method helps, thanks to DH, to recover information which, otherwise, would be completely lost.

  2. Room-temperature bonding for plastic high-pressure microfluidic chips.

    PubMed

    Mair, Dieudonne A; Rolandi, Marco; Snauko, Marian; Noroski, Richard; Svec, Frantisek; Fréchet, Jean M J

    2007-07-01

    A generic method for the rapid, reproducible, and robust bonding of microfluidic chips fabricated from plastics has been developed and optimized. One of the bonding surfaces is exposed to solvent vapor prior to bringing the mating parts into contact and applying a load. Nanoindentation measurements performed by atomic force microscopy show that a reversible material softening occurs upon exposure to solvent vapor. Subsequent exposure of the bonded chip to UV light then strengthens the bond between mating parts and increases the burst pressure by 50% due to partial cross-linking and chain scission reactions as measured by size exclusion chromatography-multiangle light scattering (SEC-MALS). Performing all steps of this procedure at room temperature eliminates channel distortion observed during thermal bonding and affords channels with highly uniform cross-sectional dimensions. Our technique enables chips resistant to pressures as high as 34.6 MPa.

  3. Microfluidic chip for stacking, separation and extraction of multiple DNA fragments.

    PubMed

    Wu, Ruige; Seah, Y P; Wang, Zhiping

    2016-03-11

    A disposable integrated microfluidic device was developed for rapid sample stacking, separation and extraction of multiple DNA fragments from a relatively large amount of sample. Isotachophoresis hyphenated gel electrophoresis (ITP-GE) was used to pre-concentrate and separate DNA fragments, followed by extraction of pure DNA fragments with electroelution on-chip. DNA fragments of 200bp, 500bp and 1kbp were successfully separated and collected in the extraction chamber within 25min. The extraction efficiency obtained from the chip was 49.9%, 52.1% and 53.7% for 200bp, 500bp and 1kbp DNA fragments, respectively. The extracted DNA fragments exhibited compatibility with downstream enzymatic reactions, for example PCR. The chip was also used to extract DNA fragments with specific size range from sheared genomic DNA and demonstrated similar performance to that using traditional gel cutting method. The whole assay can finish in 32min, 6 times faster than traditional method.

  4. A chitosan coated monolith for nucleic acid capture in a thermoplastic microfluidic chip

    PubMed Central

    Kendall, Eric L.; Wienhold, Erik; DeVoe, Don L.

    2014-01-01

    A technique for microfluidic, pH modulated DNA capture and purification using chitosan functionalized glycidyl methacrylate monoliths is presented. Highly porous polymer monoliths are formed and subsequently functionalized off-chip in a batch process before insertion into thermoplastic microchannels prior to solvent bonding, simplifying the overall fabrication process by eliminating the need for on-chip surface modifications. The monolith anchoring method allows for the use of large cross-section monoliths enabling high flowrates and high DNA capture capacity with a minimum of added design complexity. Using monolith capture elements requiring less than 1 mm2 of chip surface area, loading levels above 100 ng are demonstrated, with DNA capture and elution efficiency of 54.2% ± 14.2% achieved. PMID:25379094

  5. Asymmetric cancer-cell filopodium growth induced by electric-fields in a microfluidic culture chip.

    PubMed

    Wang, Chun-Chieh; Kao, Yu-Chiu; Chi, Pei-Yin; Huang, Ching-Wen; Lin, Jiunn-Yuan; Chou, Chia-Fu; Cheng, Ji-Yen; Lee, Chau-Hwang

    2011-02-21

    We combine a micro-fluidic electric-field cell-culture (MEC) chip with structured-illumination nano-profilometry (SINAP) to quantitatively study the variations of cancer cell filopodia under external direct-current electric field (dcEF) stimulations. Because the lateral resolution of SINAP is better than 150 nm in bright-field image modality, filopodia with diameters smaller than 200 nm can be observed clearly without fluorescent labeling. In the MEC chip, a homogeneous EF is generated inside the culture area that simulates the endogenous EF environment. With this MEC chip-SINAP system, we directly observe and quantify the biased growth of filopodia of lung cancer cells toward the cathode. The epidermal growth factor receptors around the cell edges are also redistributed to the cathodal side. These results suggest that cancer-cell filopodia respond to the changes in EFs in the microenvironment.

  6. A mechanical cell disruption microfluidic platform based on an on-chip micropump.

    PubMed

    Cheng, Yinuo; Wang, Yue; Wang, Zhiyuan; Huang, Liang; Bi, Mingzhao; Xu, Wenxiao; Wang, Wenhui; Ye, Xiongying

    2017-03-01

    Cell disruption plays a vital role in detection of intracellular components which contain information about genetic and disease characteristics. In this paper, we demonstrate a novel microfluidic platform based on an on-chip micropump for mechanical cell disruption and sample transport. A 50 μl cell sample can be effectively lysed through on-chip multi-disruption in 36 s without introducing any chemical agent and suffering from clogging by cellular debris. After 30 cycles of circulating disruption, 80.6% and 90.5% cell disruption rates were achieved for the HEK293 cell sample and human natural killer cell sample, respectively. Profiting from the feature of pump-on-chip, the highly integrated platform enables more convenient and cost-effective cell disruption for the analysis of intracellular components.

  7. Rapid cell-patterning and microfluidic chip fabrication by crack-free CO2 laser ablation on glass

    NASA Astrophysics Data System (ADS)

    Yen, Meng-Hua; Cheng, Ji-Yen; Wei, Cheng-Wey; Chuang, Yung-Chuan; Young, Tai-Horng

    2006-07-01

    This paper uses a widely available CO2 laser scriber (λ = 10.6 µm) to perform the direct-writing ablation of quartz, borofloat and pyrex substrates for the development of microfluidic chips and cell chips. The surface quality of the ablated microchannels and the presence of debris and distortion are examined by scanning electron microscopy, atomic force microscopy and surface profile measurement techniques. The developed laser ablation system provides a versatile and economic approach for the fabrication of glass microfluidic chips with crack-free structures. In the laser writing process, the desired microfluidic patterns are designed using commercial computer software and are then transferred to the laser scriber to ablate the trenches. This process eliminates the requirement for corrosive chemicals and photomasks, and hence the overall microchip development time is limited to less than 24 h. Additionally, since the laser writing process is not limited by the dimensions of a photomask, the microchannels can be written over a large substrate area. The machining capability and versatility of the laser writing system are demonstrated through its application to the fabrication of a borofloat microfluidic chip and the writing of a series of asymmetric trenches in a microwell array. It is shown that the minimum attainable trench width is 95 µm and that the maximum trench depth is 225 µm. The system provides an economic and powerful means of rapid glass microfluidic chip development. A rapid cell-patterning method based on this method is also demonstrated.

  8. Microfluidic high performance liquid chromatography-chip hyphenation to inductively coupled plasma-mass spectrometry.

    PubMed

    Bishop, David P; Blanes, Lucas; Wilson, Alexander B; Wilbanks, Thor; Killeen, Kevin; Grimm, Rudolf; Wenzel, Ross; Major, Derek; Macka, Mirek; Clarke, David; Schmid, Robin; Cole, Nerida; Doble, Philip A

    2017-05-12

    The Agilent Chip Cube Interface is a microfluidic chip-based technology originally designed for nanospray molecular mass spectrometry in which the sample enrichment, nano-column, tubing, connectors and spray tip were integrated into a single biocompatible chip. Here we describe the hyphenation of the Chip Cube Interface to ICP-MS via modification of the standard HPLC chip design and a new total consumption nebuliser suitable for flow rates as low as 300nLmin(-1). The potential of the instrument to eliminate common nanoLC - ICP-MS shortcomings such as leaks, blockages and band-broadening was demonstrated via analysis of cyanocobalamin in equine plasma. The method was linear over three orders of magnitude with an r(2) of 0.9999, the peak area repeatability was 1.9% (n=7), and the detection limit was 14ngmL(-1). This novel configuration of the Chip Cube Interface coupled to ICP-MS is a suitable platform for the analysis of biomolecules associated with trace metals and speciation applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. A microfluidic chip for controlled release of drugs from microcapsules

    PubMed Central

    Cheng, Wen-Chuan; He, Yuan; Chang, An-Yi; Que, Long

    2013-01-01

    A new microfluidic device with liquid-droplet merging and droplet storage functions for the controlled release of drugs from microcapsules is reported. A switching channel is designed and integrated within the microfluidic device, facilitating the generation and capturing of uniform droplets by the storage chambers. The drug model is the MnCO3 microparticle, which is encapsulated by a microcapsule and fabricated using a simple layer-by-layer nanoassembly process. The merging function is used for dynamically adding the control solution into the droplets, which contain drugs within the microcapsules (DWμCs) and water. The storage chambers are used for collecting DWμCs-laden droplets so that the controlled-drug release in specific droplets can be monitored for an extended period of time, which has been experimentally implemented successfully. This technology could offer a promising technical platform for the long-term observation and studies of drug effects on specific cells in a controlled manner, which is especially useful for single cell analysis. PMID:24396536

  10. Microfluidic chip containing porous gradient for chemotaxis study

    NASA Astrophysics Data System (ADS)

    Al-Abboodi, Aswan; Tjeung, Ricky; Doran, Pauline; Yeo, Leslie; Friend, James; Chan, Peggy

    2011-12-01

    We have developed a new porous gradient microfluidic device based on in situ Gtn-HPA/CMC-Tyr hydrogel that comprises gelatin hydroxyphenylpropionic acid (Gtn-HPA) conjugate and carboxymethyl cellulose tyramine (CMC-Tyr) conjugate. The device is fabricated using a soft lithographic technique, in which microstructures were patterned on a thin layer of polydimethylsiloxane (PDMS) using a polymeric mold. Human fibrosarcoma cells (HT1080) were employed as invasive cancer cell model. Porosity gradients were generated by flowing pore etching fluid in the gradient generator network. Results suggested that spatial control of the porosity can be obtained, which mimics the 3-dimensional microenvironment in vivo for cell-based screening applications including real time chemotaxis, cytotoxicity, and continuous drug-response monitoring. A chemoattractant gradient is then generated and cell migration is monitored in real time using fluorescence microscopy. The viability of cells was evaluated using calcien AM stain. Herein, we successfully monitored the chemotactic responses of cancer cells, confirmed the validity of using in situ porous hydrogels as a construction material for a microchemotaxis device, and demonstrated the potential of the hydrogel with tunable porosity based microfluidic device in biological experiments. This device will also be practical in controlling the chemical and mechanical properties of the surroundings during the formation of tissue engineered constructs.

  11. Tape underlayment rotary-node (TURN) valves for simple on-chip microfluidic flow control.

    PubMed

    Markov, Dmitry A; Manuel, Steven; Shor, Leslie M; Opalenik, Susan R; Wikswo, John P; Samson, Philip C

    2010-02-01

    We describe a simple and reliable fabrication method for producing multiple, manually activated microfluidic control valves in polydimethylsiloxane (PDMS) devices. These screwdriver-actuated valves reside directly on the microfluidic chip and can provide both simple on/off operation as well as graded control of fluid flow. The fabrication procedure can be easily implemented in any soft lithography lab and requires only two specialized tools-a hot-glue gun and a machined brass mold. To facilitate use in multi-valve fluidic systems, the mold is designed to produce a linear tape that contains a series of plastic rotary nodes with small stainless steel machine screws that form individual valves which can be easily separated for applications when only single valves are required. The tape and its valves are placed on the surface of a partially cured thin PDMS microchannel device while the PDMS is still on the soft-lithographic master, with the master providing alignment marks for the tape. The tape is permanently affixed to the microchannel device by pouring an over-layer of PDMS, to form a full-thickness device with the tape as an enclosed underlayment. The advantages of these Tape Underlayment Rotary-Node (TURN) valves include parallel fabrication of multiple valves, low risk of damaging a microfluidic device during valve installation, high torque, elimination of stripped threads, the capabilities of TURN hydraulic actuators, and facile customization of TURN molds. We have utilized these valves to control microfluidic flow, to control the onset of molecular diffusion, and to manipulate channel connectivity. Practical applications of TURN valves include control of loading and chemokine release in chemotaxis assay devices, flow in microfluidic bioreactors, and channel connectivity in microfluidic devices intended to study competition and predator/prey relationships among microbes.

  12. Tape underlayment rotary-node (TURN) valves for simple on-chip microfluidic flow control

    PubMed Central

    Markov, Dmitry A.; Manuel, Steven; Shor, Leslie M.; Opalenik, Susan R.; Wikswo, John P.; Samson, Philip C.

    2013-01-01

    We describe a simple and reliable fabrication method for producing multiple, manually activated microfluidic control valves in polydimethylsiloxane (PDMS) devices. These screwdriver-actuated valves reside directly on the microfluidic chip and can provide both simple on/off operation as well as graded control of fluid flow. The fabrication procedure can be easily implemented in any soft lithography lab and requires only two specialized tools – a hot-glue gun and a machined brass mold. To facilitate use in multi-valve fluidic systems, the mold is designed to produce a linear tape that contains a series of plastic rotary nodes with small stainless steel machine screws that form individual valves which can be easily separated for applications when only single valves are required. The tape and its valves are placed on the surface of a partially cured thin PDMS microchannel device while the PDMS is still on the soft-lithographic master, with the master providing alignment marks for the tape. The tape is permanently affixed to the microchannel device by pouring an over-layer of PDMS, to form a full-thickness device with the tape as an enclosed underlayment. The advantages of these Tape Underlayment Rotary-Node (TURN) valves include parallel fabrication of multiple valves, low risk of damaging a microfluidic device during valve installation, high torque, elimination of stripped threads, the capabilities of TURN hydraulic actuators, and facile customization of TURN molds. We have utilized these valves to control microfluidic flow, to control the onset of molecular diffusion, and to manipulate channel connectivity. Practical applications of TURN valves include control of loading and chemokine release in chemotaxis assay devices, flow in microfluidic bioreactors, and channel connectivity in microfluidic devices intended to study competition and predator / prey relationships among microbes. PMID:19859812

  13. Algal fluorescence sensor integrated into a microfluidic chip for water pollutant detection.

    PubMed

    Lefèvre, Florent; Chalifour, Annie; Yu, Luping; Chodavarapu, Vamsy; Juneau, Philippe; Izquierdo, Ricardo

    2012-02-21

    We report the first miniaturized fluorescent sensor based on algae, with an organic light emitting diode (OLED) and an organic photodetector (OPD) integrated into a microfluidic chip. The blue emission OLED was used as the excitation source, while a blend of PTB3/PC(61)BM was used for the fabrication of the organic photodetector. Excitation and emission color filters based on acid/base dyes and a metal complex were developed and assembled with the organic optoelectronic components in order to complete the fluorescent detection system. The detection system was then integrated in a microfluidic chip made from (poly)dimethylsiloxane (PDMS). The complete sensor is designed to detect algal fluorescence in the microfluidic chamber. Algal chlorophyll fluorescence enables evaluation of the toxicity of pollutants like herbicides and metals-ions from agricultural run-offs. The entirely organic bioassay here presented allowed detection of the toxic effects of the herbicide Diuron on Chlamydomonas reinhardtii green algae that gave 50% inhibition of the algae photochemistry (EC(50)) with a concentration as low as 11 nM.

  14. Microfluidic chip system for the selection and enrichment of cell binding aptamers

    PubMed Central

    Stoll, Heidi; Kiessling, Heiko; Stelzle, Martin; Wendel, Hans Peter; Schütte, Julia; Hagmeyer, Britta; Avci-Adali, Meltem

    2015-01-01

    Aptamers are promising cell targeting ligands for several applications such as for the diagnosis, therapy, and drug delivery. Especially, in the field of regenerative medicine, stem cell specific aptamers have an enormous potential. Using the combinatorial chemistry process SELEX (Systematic Evolution of Ligands by Exponential enrichment), aptamers are selected from a huge oligonucleotide library consisting of approximately 1015 different oligonucleotides. Here, we developed a microfluidic chip system that can be used for the selection of cell specific aptamers. The major drawbacks of common cell-SELEX methods are the inefficient elimination of the unspecifically bound oligonucleotides from the cell surface and the unspecific binding/uptake of oligonucleotides by dead cells. To overcome these obstacles, a microfluidic device, which enables the simultaneous performance of dielectrophoresis and electrophoresis in the same device, was designed. Using this system, viable cells can be selectively assembled by dielectrophoresis between the electrodes and then incubated with the oligonucleotides. To reduce the rate of unspecifically bound sequences, electrophoretic fields can be applied in order to draw loosely bound oligonucleotides away from the cells. Furthermore, by increasing the flow rate in the chip during the iterative rounds of SELEX, the selection pressure can be improved and aptamers with higher affinities and specificities can be obtained. This new microfluidic device has a tremendous capability to improve the cell-SELEX procedure and to select highly specific aptamers. PMID:26180568

  15. Metabolomics-on-a-chip and predictive systems toxicology in microfluidic bioartificial organs.

    PubMed

    Shintu, Laetitia; Baudoin, Régis; Navratil, Vincent; Prot, Jean-Matthieu; Pontoizeau, Clément; Defernez, Marianne; Blaise, Benjamin J; Domange, Céline; Péry, Alexandre R; Toulhoat, Pierre; Legallais, Cécile; Brochot, Céline; Leclerc, Eric; Dumas, Marc-Emmanuel

    2012-02-21

    The world faces complex challenges for chemical hazard assessment. Microfluidic bioartificial organs enable the spatial and temporal control of cell growth and biochemistry, critical for organ-specific metabolic functions and particularly relevant to testing the metabolic dose-response signatures associated with both pharmaceutical and environmental toxicity. Here we present an approach combining a microfluidic system with (1)H NMR-based metabolomic footprinting, as a high-throughput small-molecule screening approach. We characterized the toxicity of several molecules: ammonia (NH(3)), an environmental pollutant leading to metabolic acidosis and liver and kidney toxicity; dimethylsulfoxide (DMSO), a free radical-scavenging solvent; and N-acetyl-para-aminophenol (APAP, or paracetamol), a hepatotoxic analgesic drug. We report organ-specific NH(3) dose-dependent metabolic responses in several microfluidic bioartificial organs (liver, kidney, and cocultures), as well as predictive (99% accuracy for NH(3) and 94% for APAP) compound-specific signatures. Our integration of microtechnology, cell culture in microfluidic biochips, and metabolic profiling opens the development of so-called "metabolomics-on-a-chip" assays in pharmaceutical and environmental toxicology.

  16. On-chip integration of droplet microfluidics and nanostructure-initiator mass spectrometry for enzyme screening.

    PubMed

    Heinemann, Joshua; Deng, Kai; Shih, Steve C C; Gao, Jian; Adams, Paul D; Singh, Anup K; Northen, Trent R

    2017-01-17

    Biological assays often require expensive reagents and tedious manipulations. These shortcomings can be overcome using digitally operated microfluidic devices that require reduced sample volumes to automate assays. One particular challenge is integrating bioassays with mass spectrometry based analysis. Towards this goal we have developed μNIMS, a highly sensitive and high throughput technique that integrates droplet microfluidics with nanostructure-initiator mass spectrometry (NIMS). Enzyme reactions are carried out in droplets that can be arrayed on discrete NIMS elements at defined time intervals for subsequent mass spectrometry analysis, enabling time resolved enzyme activity assay. We apply the μNIMS platform for kinetic characterization of a glycoside hydrolase enzyme (CelE-CMB3A), a chimeric enzyme capable of deconstructing plant hemicellulose into monosaccharides for subsequent conversion to biofuel. This study reveals NIMS nanostructures can be fabricated into arrays for microfluidic droplet deposition, NIMS is compatible with droplet and digital microfluidics, and can be used on-chip to assay glycoside hydrolase enzyme in vitro.

  17. Radiolabelling diverse positron emission tomography (PET) tracers using a single digital microfluidic reactor chip.

    PubMed

    Chen, Supin; Javed, Muhammad Rashed; Kim, Hee-Kwon; Lei, Jack; Lazari, Mark; Shah, Gaurav J; van Dam, R Michael; Keng, Pei-Yuin; Kim, Chang-Jin C J

    2014-03-07

    Radiotracer synthesis is an ideal application for microfluidics because only nanogram quantities are needed for positron emission tomography (PET) imaging. Thousands of radiotracers have been developed in research settings but only a few are readily available, severely limiting the biological problems that can be studied in vivo via PET. We report the development of an electrowetting-on-dielectric (EWOD) digital microfluidic chip that can synthesize a variety of (18)F-labeled tracers targeting a range of biological processes by confirming complete syntheses of four radiotracers: a sugar, a DNA nucleoside, a protein labelling compound, and a neurotransmitter. The chip employs concentric multifunctional electrodes that are used for heating, temperature sensing, and EWOD actuation. All of the key synthesis steps for each of the four (18)F-labeled tracers are demonstrated and characterized with the chip: concentration of fluoride ion, solvent exchange, and chemical reactions. The obtained fluorination efficiencies of 90-95% are comparable to, or greater than, those achieved by conventional approaches.

  18. Fabrication and validation of a multi-channel type microfluidic chip for electrokinetic streaming potential devices.

    PubMed

    Chun, Myung-Suk; Shim, Min Suk; Choi, Nak Won

    2006-02-01

    To elaborate on the applicability of the electrokinetic micro power generation, we designed and fabricated the silicon-glass as well as the PDMS-glass microfluidic chips with the unique features of a multi-channel. Besides miniaturizing the device, the key advantage of our microfluidic chip utilization lies in the reduction in water flow rate. Both a distributor and a collector taking the tapered duct geometry are positioned aiming the uniform distribution of water flow into all individual channels of the chip, in which several hundreds of single microchannels are assembled in parallel. A proper methodology is developed accompanying the deep reactive ion etching as well as the anodic bonding, and optimum process conditions necessary for hard and soft micromachining are presented. It has been shown experimentally and theoretically that the silicon-based microchannel leads to increasing streaming potential and higher external current compared to those of the PDMS-based one. A proper comparison between experimental results and theoretical computations allows justification of the validity of our novel devices. It is useful to recognize that a material inducing a higher magnitude of zeta potential has an advantage for obtaining higher power density under the same external resistance.

  19. Euler force actuation mechanism for siphon valving in compact disk-like microfluidic chips.

    PubMed

    Deng, Yongbo; Fan, Jianhua; Zhou, Song; Zhou, Teng; Wu, Junfeng; Li, Yin; Liu, Zhenyu; Xuan, Ming; Wu, Yihui

    2014-03-01

    Based on the Euler force induced by the acceleration of compact disk (CD)-like microfluidic chip, this paper presents a novel actuation mechanism for siphon valving. At the preliminary stage of acceleration, the Euler force in the tangential direction of CD-like chip takes the primary place compared with the centrifugal force to function as the actuation of the flow, which fills the siphon and actuates the siphon valving. The Euler force actuation mechanism is demonstrated by the numerical solution of the phase-field based mathematical model for the flow in siphon valve. In addition, experimental validation is implemented in the polymethylmethacrylate-based CD-like microfluidic chip manufactured using CO2 laser engraving technique. To prove the application of the proposed Euler force actuation mechanism, whole blood separation and plasma extraction has been conducted using the Euler force actuated siphon valving. The newly introduced actuation mechanism overcomes the dependence on hydrophilic capillary filling of siphon by avoiding external manipulation or surface treatments of polymeric material. The sacrifice for highly integrated processing in pneumatic pumping technique is also prevented by excluding the volume-occupied compressed air chamber.

  20. Microfluidic chip integrating high throughput continuous-flow PCR and DNA hybridization for bacteria analysis.

    PubMed

    Jiang, Xiran; Shao, Ning; Jing, Wenwen; Tao, Shengce; Liu, Sixiu; Sui, Guodong

    2014-05-01

    Rapid identification of clinical pathogens is the initial and essential step for antimicrobial therapy. Herein, we successfully developed a microfluidic device which combines high-throughput continuous-flow PCR and DNA hybridization for the detection of various bacterial pathogens. Universal primers were designed based on the conserved regions of bacterial 16S ribosomal DNA (16S rDNA), and specific probes were designed from a variable region of 16S rDNA within the amplicon sequences. In the chip operation, after the continuous flow PCR was achieved in the first microfluidic chip, the product was directly introduced into a hybridization chip integrated with microarray containing the immobilized DNA probes. The target-probe hybridization was completed within 1h at 55 °C, and fluorescence signals were obtained as the readout. The presented device is simple, versatile and with less sample consumption compared with traditional instruments. It can perform high-throughput bacteria detections continuously in a single assay, which makes it a promising platform for clinical bacteria identifications.

  1. High adhesion strength and hybrid irreversible/reversible full-PDMS microfluidic chips.

    PubMed

    Shiroma, Letícia S; Oliveira, Aline F; Lobo-Júnior, Eulicio O; Coltro, Wendell K T; Gobbi, Angelo L; de La Torre, Lucimara G; Lima, Renato S

    2017-01-25

    To the best of our knowledge, this paper outlines for the first time high adhesion and hybrid irreversible/reversible microfluidic devices fully composed of polydimethylsiloxane (PDMS). These chips were fabricated by the sandwich bonding (SWB), a method that was recently deployed by our group. SWB offers simple, fast, and low cost operation requiring only a laboratory oven. The devices showed burst pressures of up to 4.5 MPa. This value is more than tenfold the pressures withstood by the full-PDMS chips described in literature. In terms of the reversible behavior, the ability for disassembling the chip slides is crucial in research and development stages, especially when the device integrates high-cost components or harsh cleaning steps are needed. Following successive steps of detachment and bonding, the channels still withstood high pressures of approximately 1.8 MPa. Finally, the emulsification of corn oil 4.0% w/w to polyglycerol polyricinoleate with 10.0 μmol L(-1) rhodamine B aqueous solution was realized to show the relevance in enhancing the flow rate in microfluidics. Such experiment was conducted at total flow rates of 0.8-160.0 μL min(-1). The decrease in size and polydispersity of the droplets was observed at increasing flow rates. Monodisperse emulsions were achieved only at 160.0 μL min(-1).

  2. Fabrication of anti-protein-fouling poly(ethylene glycol) microfluidic chip electrophoresis by sandwich photolithography

    PubMed Central

    Cong, Hailin; Xu, Xiaodan; Yu, Bing; Liu, Huwei

    2016-01-01

    Microfluidic chip electrophoresis (MCE) is a powerful separation tool for biomacromolecule analysis. However, adsorption of biomacromolecules, particularly proteins onto microfluidic channels severely degrades the separation performance of MCE. In this paper, an anti-protein-fouling MCE was fabricated using a novel sandwich photolithography of poly(ethylene glycol) (PEG) prepolymers. Photopatterned microchannel with a minimum resolution of 10 μm was achieved. After equipped with a conventional online electrochemical detector, the device enabled baseline separation of bovine serum albumin, lysozyme (Lys), and cytochrome c (Cyt-c) in 53 s under a voltage of 200 V. Compared with a traditional polydimethylsiloxane MCE made by soft lithography, the PEG MCE made by the sandwich photolithography not only eliminated the need of a master mold and the additional modification process of the microchannel but also showed excellent anti-protein-fouling properties for protein separation. PMID:27493702

  3. Microfluidics-Based Lab-on-Chip Systems in DNA-Based Biosensing: An Overview

    PubMed Central

    Dutse, Sabo Wada; Yusof, Nor Azah

    2011-01-01

    Microfluidics-based lab-on-chip (LOC) systems are an active research area that is revolutionising high-throughput sequencing for the fast, sensitive and accurate detection of a variety of pathogens. LOCs also serve as portable diagnostic tools. The devices provide optimum control of nanolitre volumes of fluids and integrate various bioassay operations that allow the devices to rapidly sense pathogenic threat agents for environmental monitoring. LOC systems, such as microfluidic biochips, offer advantages compared to conventional identification procedures that are tedious, expensive and time consuming. This paper aims to provide a broad overview of the need for devices that are easy to operate, sensitive, fast, portable and sufficiently reliable to be used as complementary tools for the control of pathogenic agents that damage the environment. PMID:22163925

  4. Fabrication of anti-protein-fouling poly(ethylene glycol) microfluidic chip electrophoresis by sandwich photolithography.

    PubMed

    Cong, Hailin; Xu, Xiaodan; Yu, Bing; Liu, Huwei; Yuan, Hua

    2016-07-01

    Microfluidic chip electrophoresis (MCE) is a powerful separation tool for biomacromolecule analysis. However, adsorption of biomacromolecules, particularly proteins onto microfluidic channels severely degrades the separation performance of MCE. In this paper, an anti-protein-fouling MCE was fabricated using a novel sandwich photolithography of poly(ethylene glycol) (PEG) prepolymers. Photopatterned microchannel with a minimum resolution of 10 μm was achieved. After equipped with a conventional online electrochemical detector, the device enabled baseline separation of bovine serum albumin, lysozyme (Lys), and cytochrome c (Cyt-c) in 53 s under a voltage of 200 V. Compared with a traditional polydimethylsiloxane MCE made by soft lithography, the PEG MCE made by the sandwich photolithography not only eliminated the need of a master mold and the additional modification process of the microchannel but also showed excellent anti-protein-fouling properties for protein separation.

  5. Study of individual erythrocyte deformability susceptibility to INFeD and ethanol using a microfluidic chip

    PubMed Central

    Liu, Lihong; Huang, Sha; Xu, Xiaoying; Han, Jongyoon

    2016-01-01

    Human red blood cells (RBCs) deformability in vitro was assessed during iron dextran (INFeD) loading and/or ethanol co-administration using microfluidic deformability screening. The results showed donor-specific variations in dose dependent deformability shift were revealed below 500 μg/mL iron dextran. Two out of nine blood samples exhibited significant cell stiffening at 500 μg/mL iron dextran loading concentration (p < 0.05, Tukey test). More interestingly, co-administration of moderate amount of ethanol was identified to have significant protective effects on RBC deformability. We also noted that ethanol can reverse the deformability of impaired RBCs. Meanwhile obvious donor dependent response to ethanol administration on RBC deformability was noted using our biomimetic microfluidic chip. PMID:26964754

  6. Preparation of monodisperse PEG hydrogel composite microspheres via microfluidic chip with rounded channels

    NASA Astrophysics Data System (ADS)

    Yu, Bing; Cong, Hailin; Liu, Xuesong; Ren, Yumin; Wang, Jilei; Zhang, Lixin; Tang, Jianguo; Ma, Yurong; Akasaka, Takeshi

    2013-09-01

    An effective microfluidic method to fabricate monodisperse polyethylene glycol (PEG) hydrogel composite microspheres with tunable dimensions and properties is reported in this paper. A T-junction microfluidic chip equipped with rounded channels and online photopolymerization system is applied for the microsphere microfabrication. The shape and size of the microspheres are well controlled by the rounded channels and PEG prepolymer/silicon oil flow rate ratios. The obtained PEG/aspirin composite microspheres exhibit a sustained release of aspirin for a wide time range; the obtained PEG/Fe3O4 nanocomposite microspheres exhibit excellent magnetic properties; and the obtained binary PEG/dye composite microspheres show the ability to synchronously load two functional components in the same peanut-shaped or Janus hydrogel particles.

  7. Heteronanojunctions with atomic size control using a lab-on-chip electrochemical approach with integrated microfluidics

    NASA Astrophysics Data System (ADS)

    Lunca Popa, P.; Dalmas, G.; Faramarzi, V.; Dayen, J. F.; Majjad, H.; Kemp, N. T.; Doudin, B.

    2011-05-01

    A versatile tool for electrochemical fabrication of heteronanojunctions with nanocontacts made of a few atoms and nanogaps of molecular spacing is presented. By integrating microfluidic circuitry in a lab-on-chip approach, we keep control of the electrochemical environment in the vicinity of the nanojunction and add new versatility for exchanging and controlling the junction's medium. Nanocontacts made of various materials by successive local controlled depositions are demonstrated, with electrical properties revealing sizes reaching a few atoms only. Investigations on benchmark molecular electronics material, trapped between electrodes, reveal the possibility to create nanogaps of size matching those of molecules. We illustrate the interest of a microfluidic approach by showing that exposure of a fabricated molecular junction to controlled high solvent flows can be used as a reliability criterion for the presence of molecular entities in a gap.

  8. Microfluidic Organ/Body-on-a-Chip Devices at the Convergence of Biology and Microengineering

    PubMed Central

    Perestrelo, Ana Rubina; Águas, Ana C. P.; Rainer, Alberto; Forte, Giancarlo

    2015-01-01

    Recent advances in biomedical technologies are mostly related to the convergence of biology with microengineering. For instance, microfluidic devices are now commonly found in most research centers, clinics and hospitals, contributing to more accurate studies and therapies as powerful tools for drug delivery, monitoring of specific analytes, and medical diagnostics. Most remarkably, integration of cellularized constructs within microengineered platforms has enabled the recapitulation of the physiological and pathological conditions of complex tissues and organs. The so-called “organ-on-a-chip” technology, which represents a new avenue in the field of advanced in vitro models, with the potential to revolutionize current approaches to drug screening and toxicology studies. This review aims to highlight recent advances of microfluidic-based devices towards a body-on-a-chip concept, exploring their technology and broad applications in the biomedical field. PMID:26690442

  9. Microfluidics-based lab-on-chip systems in DNA-based biosensing: an overview.

    PubMed

    Dutse, Sabo Wada; Yusof, Nor Azah

    2011-01-01

    Microfluidics-based lab-on-chip (LOC) systems are an active research area that is revolutionising high-throughput sequencing for the fast, sensitive and accurate detection of a variety of pathogens. LOCs also serve as portable diagnostic tools. The devices provide optimum control of nanolitre volumes of fluids and integrate various bioassay operations that allow the devices to rapidly sense pathogenic threat agents for environmental monitoring. LOC systems, such as microfluidic biochips, offer advantages compared to conventional identification procedures that are tedious, expensive and time consuming. This paper aims to provide a broad overview of the need for devices that are easy to operate, sensitive, fast, portable and sufficiently reliable to be used as complementary tools for the control of pathogenic agents that damage the environment.

  10. Heteronanojunctions with atomic size control using a lab-on-chip electrochemical approach with integrated microfluidics.

    PubMed

    Lunca Popa, P; Dalmas, G; Faramarzi, V; Dayen, J F; Majjad, H; Kemp, N T; Doudin, B

    2011-05-27

    A versatile tool for electrochemical fabrication of heteronanojunctions with nanocontacts made of a few atoms and nanogaps of molecular spacing is presented. By integrating microfluidic circuitry in a lab-on-chip approach, we keep control of the electrochemical environment in the vicinity of the nanojunction and add new versatility for exchanging and controlling the junction's medium. Nanocontacts made of various materials by successive local controlled depositions are demonstrated, with electrical properties revealing sizes reaching a few atoms only. Investigations on benchmark molecular electronics material, trapped between electrodes, reveal the possibility to create nanogaps of size matching those of molecules. We illustrate the interest of a microfluidic approach by showing that exposure of a fabricated molecular junction to controlled high solvent flows can be used as a reliability criterion for the presence of molecular entities in a gap.

  11. Microfluidic channels with ultralow-loss waveguide crossings for various chip-integrated photonic sensors.

    PubMed

    Wang, Zheng; Yan, Hai; Chakravarty, Swapnajit; Subbaraman, Harish; Xu, Xiaochuan; Fan, D L; Wang, Alan X; Chen, Ray T

    2015-04-01

    Traditional silicon waveguides are defined by waveguide trenches on either side of the high-index silicon core that leads to fluid leakage orifices for over-layed microfluidic channels. Closing the orifices needs additional fabrication steps which may include oxide deposition and planarization. We experimentally demonstrated a new type of microfluidic channel design with ultralow-loss waveguide crossings (0.00248 dB per crossings). The waveguide crossings and all other on-chip passive-waveguide components are fabricated in one step with no additional planarization steps which eliminates any orifices and leads to leak-free fluid flow. Such designs are applicable in all optical-waveguide-based sensing applications where the analyte must be flowed over the sensor. The new channel design was demonstrated in a L55 photonic crystal sensor operating between 1540 and 1580 nm.

  12. Determination of adrenal steroids by microfluidic chip using micellar electrokinetic chromatography.

    PubMed

    Shen, Shuanglong; Li, Yan; Wakida, Shin-ichi; Takeda, Sahori

    2009-06-01

    This paper describes a sensitive and convenient method to separate progesterone, 17alpha-hydroxy progesterone, cortexolone, hydrocortisone and cortisone, all of which are steroids and have similar structures, using microfluidic chip-based technology with UV detection at 252 nm. We successfully obtained high-speed separation of the five steroids within 70 s in optimized microfluidic controls and micellar electrokinetic chromatography (MEKC) separation conditions. Fairly good linearity with correlation coefficient of over 0.98 from 10 or 20 to 100 mg/l steroid chemicals was obtained. The limits of detection obtained at a signal to noise ratio of 3 were from 3.89 to 7.80 mg/l. The values of the relative standard deviation (RSD) were 0.98-1.34% for repetitive injection (n = 12) and the intraday and interday RSDs were below 6%. The highly stable response reflected the feasibility of this method.

  13. Development of multistage distillation in a microfluidic chip.

    PubMed

    Lam, K F; Cao, E; Sorensen, E; Gavriilidis, A

    2011-04-07

    Although there has been a lot of work on the development of microchemical processing systems such as micro-reactors and micro-sensors, little attention has been paid to micro-separation units, and in particular, microscale distillation. In this paper, various silicon-glass microscale distillation chips with different channel configurations were fabricated and tested. A temperature gradient was setup across the chip by heating and cooling the two ends. The feed was located at the middle of the microchannel. Arrays of micropillars were incorporated in order to guide the liquid flow. It was found that the separation performance was promoted by increasing the length of the microchannel. However, this created an imbalance of the liquid flows at the two sides of the microchannel and caused flooding. This hydrodynamic limitation was addressed by incorporating micropillars on both sides of the channel. The most efficient microdistillation chip consisted of a microchannel with 600 microns width and 40 cm length. Experimental results showed high efficiency for the separation of a 50 mol% acetone-water mixture when the heating and cooling temperature were 95 °C and 42 °C respectively. The concentrations of acetone were 3 mol% in the bottom stream and 95 mol% in the distillate, which was equivalent to at least 4 equilibrium stages at total reflux conditions. Furthermore, a 50 mol% methanol-toluene mixture was separated into nearly pure toluene in the bottom stream and 75 mol% methanol in the distillate. The performance of the microdistillation unit was reproducible in repeated tests.

  14. Determination of Apparent Amylose Content in Rice by Using Paper-Based Microfluidic Chips.

    PubMed

    Hu, Xianqiao; Lu, Lin; Fang, Changyun; Duan, Binwu; Zhu, Zhiwei

    2015-11-11

    Determination of apparent amylose content in rice is a key function for rice research and the rice industry. In this paper, a novel approach with paper-based microfluidic chip is reported to determine apparent amylose content in rice. The conventional color reaction between amylose and iodine was employed. Blue color of amylose-iodine complex generated on-chip was converted to gray and measured with Photoshop after the colored chip was scanned. The method for preparation of the paper chip is described. In situ generation of iodine for on-chip color reaction was designed, and factors influencing color reaction were investigated in detail. Elimination of yellow color interference of excess iodine by exploiting color removal function of Photoshop was presented. Under the optimized conditions, apparent amylose content in rice ranging from 1.5 to 26.4% can be determined, and precision was 6.3%. The analytical results obtained with the developed approach were in good agreement with those with the continuous flow analyzer method.

  15. Immuno-capture and in situ detection of Salmonella typhimurium on a novel microfluidic chip.

    PubMed

    Wang, Renjie; Ni, Yanan; Xu, Yi; Jiang, Yan; Dong, Chunyan; Chuan, Na

    2015-01-01

    The new method presented in this article achieved the goal of capturing Salmonella typhimurium via immunoreaction and rapid in situ detection of the CdSe/ZnS quantum dots (QDs) labeled S. typhimurium by self-assembly light-emitting diode-induced fluorescence detection (LIF) microsystem on a specially designed multichannel microfluidic chip. CdSe/ZnS QDs were used as fluorescent markers improving detection sensitivity. The microfluidic chip developed in this study was composed of 12 sample channels, 3 mixing zones, and 6 immune reaction zones, which also acted as fluorescence detection zones. QDs-IgG-primary antibody complexes were generated by mixing CdSe/ZnS QDs conjugated secondary antibody (QDs-IgG) and S. typhimurium antibody (primary antibody) in mixing zones. Then, the complexes went into immune reaction zones to label previously captured S. typhimurium in the sandwich mode. The capture rate of S. typhimurium in each detection zone was up to 70%. The enriched QDs-labeled S. typhimurium was detected using a self-assembly LIF microsystem. A good linear relationship was obtained in the range from 3.7×10 to 3.7×10(5) cfu mL(-1) using the equation I=0.1739 log (C)-0.1889 with R(2)=0.9907, and the detection limit was down to 37 cfu mL(-1). The proposed method of online immunolabeling with QDs for in situ fluorescence detection on the designed multichannel microfluidic chip had been successfully used to detect S. typhimurium in pork sample, and it has shown potential advantages in practice.

  16. A Novel Electrochemical Microfluidic Chip Combined with Multiple Biomarkers for Early Diagnosis of Gastric Cancer

    NASA Astrophysics Data System (ADS)

    Xie, Yao; Zhi, Xiao; Su, Haichuan; Wang, Kan; Yan, Zhen; He, Nongyue; Zhang, Jingpu; Chen, Di; Cui, Daxiang

    2015-12-01

    Early diagnosis is very important to improve the survival rate of patients with gastric cancer and to understand the biology of cancer. In order to meet the clinical demands for early diagnosis of gastric cancer, we developed a disposable easy-to-use electrochemical microfluidic chip combined with multiple antibodies against six kinds of biomarkers (carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), Helicobacter pylori CagA protein (H.P.), P53oncoprotein (P53), pepsinogen I (PG I), and PG-II). The six kinds of biomarkers related to gastric cancer can be detected sensitively and synchronously in a short time. The specially designed three electrodes system enables cross-contamination to be avoided effectively. The linear ranges of detection of the electrochemical microfluidic chip were as follows: 0.37-90 ng mL-1 for CEA, 10.75-172 U mL-1 for CA19-9, 10-160 U L-1 for H.P., 35-560 ng mL-1 for P53, 37.5-600 ng mL-1 for PG I, and 2.5-80 ng mL-1for PG II. This method owns better sensitivity compared with enzyme-linked immunosorbent assay (ELISA) results of 394 specimens of gastric cancer sera. Furthermore, we established a multi-index prediction model based on the six kinds of biomarkers for predicting risk of gastric cancer. In conclusion, the electrochemical microfluidic chip for detecting multiple biomarkers has great potential in applications such as early screening of gastric cancer patients, and therapeutic evaluation, and real-time dynamic monitoring the progress of gastric cancer in near future.

  17. A Novel Electrochemical Microfluidic Chip Combined with Multiple Biomarkers for Early Diagnosis of Gastric Cancer.

    PubMed

    Xie, Yao; Zhi, Xiao; Su, Haichuan; Wang, Kan; Yan, Zhen; He, Nongyue; Zhang, Jingpu; Chen, Di; Cui, Daxiang

    2015-12-01

    Early diagnosis is very important to improve the survival rate of patients with gastric cancer and to understand the biology of cancer. In order to meet the clinical demands for early diagnosis of gastric cancer, we developed a disposable easy-to-use electrochemical microfluidic chip combined with multiple antibodies against six kinds of biomarkers (carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), Helicobacter pylori CagA protein (H.P.), P53oncoprotein (P53), pepsinogen I (PG I), and PG-II). The six kinds of biomarkers related to gastric cancer can be detected sensitively and synchronously in a short time. The specially designed three electrodes system enables cross-contamination to be avoided effectively. The linear ranges of detection of the electrochemical microfluidic chip were as follows: 0.37-90 ng mL(-1) for CEA, 10.75-172 U mL(-1) for CA19-9, 10-160 U L(-1) for H.P., 35-560 ng mL(-1) for P53, 37.5-600 ng mL(-1) for PG I, and 2.5-80 ng mL(-1)for PG II. This method owns better sensitivity compared with enzyme-linked immunosorbent assay (ELISA) results of 394 specimens of gastric cancer sera. Furthermore, we established a multi-index prediction model based on the six kinds of biomarkers for predicting risk of gastric cancer. In conclusion, the electrochemical microfluidic chip for detecting multiple biomarkers has great potential in applications such as early screening of gastric cancer patients, and therapeutic evaluation, and real-time dynamic monitoring the progress of gastric cancer in near future.

  18. Investigating Nonalcoholic Fatty Liver Disease in a Liver-on-a-Chip Microfluidic Device

    PubMed Central

    Simonelli, Maria Chiara; Giannitelli, Sara Maria; Businaro, Luca; Trombetta, Marcella; Rainer, Alberto

    2016-01-01

    Background and Aim Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease worldwide, ranging from simple steatosis to nonalcoholic steatohepatitis, which may progress to cirrhosis, eventually leading to hepatocellular carcinoma (HCC). HCC ranks as the third highest cause of cancer-related death globally, requiring an early diagnosis of NAFLD as a potential risk factor. However, the molecular mechanisms underlying NAFLD are still under investigation. So far, many in vitro studies on NAFLD have been hampered by the limitations of 2D culture systems, in which cells rapidly lose tissue-specific functions. The present liver-on-a-chip approach aims at filling the gap between conventional in vitro models, often scarcely predictive of in vivo conditions, and animal models, potentially biased by their xenogeneic nature. Methods HepG2 cells were cultured into a microfluidically perfused device under free fatty acid (FFA) supplementation, namely palmitic and oleic acid, for 24h and 48h. The device mimicked the endothelial-parenchymal interface of a liver sinusoid, allowing the diffusion of nutrients and removal of waste products similar to the hepatic microvasculature. Assessment of intracellular lipid accumulation, cell viability/cytotoxicity and oxidative stress due to the FFA overload, was performed by high-content analysis methodologies using fluorescence-based functional probes. Results The chip enables gradual and lower intracellular lipid accumulation, higher hepatic cell viability and minimal oxidative stress in microfluidic dynamic vs. 2D static cultures, thus mimicking the chronic condition of steatosis observed in vivo more closely. Conclusions Overall, the liver-on-a-chip system provides a suitable culture microenvironment, representing a more reliable model compared to 2D cultures for investigating NAFLD pathogenesis. Hence, our system is amongst the first in vitro models of human NAFLD developed within a microfluidic device in a sinusoid

  19. Microfluidic heart on a chip for higher throughput pharmacological studies.

    PubMed

    Agarwal, Ashutosh; Goss, Josue Adrian; Cho, Alexander; McCain, Megan Laura; Parker, Kevin Kit

    2013-09-21

    We present the design of a higher throughput "heart on a chip" which utilizes a semi-automated fabrication technique to process sub millimeter sized thin film cantilevers of soft elastomers. Anisotropic cardiac microtissues which recapitulate the laminar architecture of the heart ventricle are engineered on these cantilevers. Deflection of these cantilevers, termed Muscular Thin Films (MTFs), during muscle contraction allows calculation of diastolic and systolic stresses generated by the engineered tissues. We also present the design of a reusable one channel fluidic microdevice completely built out of autoclavable materials which incorporates various features required for an optical cardiac contractility assay: metallic base which fits on a heating element for temperature control, transparent top for recording cantilever deformation and embedded electrodes for electrical field stimulation of the tissue. We employ the microdevice to test the positive inotropic effect of isoproterenol on cardiac contractility at dosages ranging from 1 nM to 100 μM. The higher throughput fluidic heart on a chip has applications in testing of cardiac tissues built from rare or expensive cell sources and for integration with other organ mimics. These advances will help alleviate translational barriers for commercial adoption of these technologies by improving the throughput and reproducibility of readout, standardization of the platform and scalability of manufacture.

  20. A Simple Microfluidic Chip Design for Fundamental Bioseparation

    PubMed Central

    Chan, Alan S.; Danquah, Michael K.; Hartley, Patrick G.; Zhu, Yonggang

    2014-01-01

    A microchip pressure-driven liquid chromatographic system with a packed column has been designed and fabricated by using poly(dimethylsiloxane) (PDMS). The liquid chromatographic column was packed with mesoporous silica beads of Ia3d space group. Separation of dyes and biopolymers was carried out to verify the performance of the chip. A mixture of dyes (fluorescein and rhodamine B) and a biopolymer mixture (10 kDa Dextran and 66 kDa BSA) were separated and the fluorescence technique was employed to detect the movement of the molecules. Fluorescein molecule was a nonretained species and rhodamine B was attached onto silica surface when dye mixture in deionized water was injected into the microchannel. The retention times for dextran molecule and BSA molecule in biopolymer separation experiment were 45 s and 120 s, respectively. Retention factor was estimated to be 3.3 for dextran and 10.4 for BSA. The selectivity was 3.2 and resolution was 10.7. Good separation of dyes and biopolymers was achieved and the chip design was verified. PMID:24527255

  1. Effect of the gelation process on the production of alginate microbeads by microfluidic chip technology.

    PubMed

    Capretto, Lorenzo; Mazzitelli, Stefania; Balestra, Cosimo; Tosi, Azzura; Nastruzzi, Claudio

    2008-04-01

    The present paper reports the production of Ba-alginate microspheres by microfluidic chip technology. The general production strategy is based on the formation of an alginate multiphase flow by a 'Y' junction squeezing mechanism. Special emphasis is given to the relationship existing between the gelation process and the final morphological characteristics of the produced microbeads. A series of different gelation strategies, namely: 'external gelation', 'internal gelation' and 'partial gelation' were compared in terms of size, size distribution and morphology of the produced microbeads.

  2. On-chip multi-gas incubation for microfluidic cell cultures under hypoxia.

    PubMed

    Takano, Atsushi; Tanaka, Masato; Futai, Nobuyuki

    2014-11-01

    We developed a simple system that regulates CO2 and O2 levels within a microfluidic chip. This system enables long-term cell culture under hypoxic conditions without the need of a CO2 incubator or a multi-gas incubator. Hypoxic conditions were generated using a miniature water jacket containing dissolved ascorbate as an oxygen scavenger. Formulations of the water jacket were determined that enables both 5% pCO2 and desired pO2 levels ranging from 5 to 15%. We also cultured PC-12 cells and primary neuronal cells from chick embryos under hypoxia and observed hypoxia-induced cell death and inhibition of neurite outgrowth.

  3. Alternating Current Cloud Point Extraction on a Microfluidic Chip: the Use of Ferrocenyl Surfactants.

    PubMed

    Usui, Yuya; Sasaki, Naoki

    2016-01-01

    Alternating current cloud point extraction (ACPE) is a preconcentration technique that can be employed in the analysis of membrane proteins on a microfluidic chip. However, the selectivity of ACPE relies on the hydrophobicity of the analytes. In this study, 11-ferrocenyltrimethylundecylammonium bromide (FTMA) was utilized to introduce electrostatic interaction as part of the ACPE technique. The use of ACPE with oxidized FTMA resulted in efficient concentration of fluorescently labeled anionic membrane proteins. We expect the approach outlined in this report to be useful in the preconcentration technique of microchip electrophoresis.

  4. Gold nanorod-facilitated localized heating of droplets in microfluidic chips.

    PubMed

    Li, Zhiyong; Wang, Pan; Tong, Limin; Zhang, Lei

    2013-01-14

    A gold nanorod-facilitated optical heating method for droplets in microfluidic chips is reported. Individual and stream nanoliter level droplets containing gold nanorods are heated by a low power 808-nm-wavelength laser. Owing to the high photothermal conversion efficiency of gold nanorods, a droplet temperature of 95 °C is achieved by employing a 13.6 mW laser with good reproducibility. The heating and cooling times are 200 and 800 ms, respectively, which are attributed to the fast thermal-transfer rates of the droplets. By controlling the irradiation laser power, the temperature cycles for polymerase chain reaction are also demonstrated.

  5. On-chip gradient generation in 256 microfluidic cell cultures: simulation and experimental validation.

    PubMed

    Somaweera, Himali; Haputhanthri, Shehan O; Ibraguimov, Akif; Pappas, Dimitri

    2015-08-07

    A microfluidic diffusion diluter was used to create a stable concentration gradient for dose response studies. The microfluidic diffusion diluter used in this study consisted of 128 culture chambers on each side of the main fluidic channel. A calibration method was used to find unknown concentrations with 12% error. Flow rate dependent studies showed that changing the flow rates generated different gradient patterns. Mathematical simulations using COMSOL Multi-physics were performed to validate the experimental data. The experimental data obtained for the flow rate studies agreed with the simulation results. Cells could be loaded into culture chambers using vacuum actuation and cultured for long times under low shear stress. Decreasing the size of the culture chambers resulted in faster gradient formation (20 min). Mass transport into the side channels of the microfluidic diffusion diluter used in this study is an important factor in creating the gradient using diffusional mixing as a function of the distance. To demonstrate the device's utility, an H2O2 gradient was generated while culturing Ramos cells. Cell viability was assayed in the 256 culture chambers, each at a discrete H2O2 concentration. As expected, the cell viability for the high concentration side channels increased (by injecting H2O2) whereas the cell viability in the low concentration side channels decreased along the chip due to diffusional mixing as a function of distance. COMSOL simulations were used to identify the effective concentration of H2O2 for cell viability in each side chamber at 45 min. The gradient effects were confirmed using traditional H2O2 culture experiments. Viability of cells in the microfluidic device under gradient conditions showed a linear relationship with the viability of the traditional culture experiment. Development of the microfluidic device used in this study could be used to study hundreds of concentrations of a compound in a single experiment.

  6. Miniature interferometer for refractive index measurement in microfluidic chip

    NASA Astrophysics Data System (ADS)

    Chen, Minghui; Geiser, Martial; Truffer, Frederic; Song, Chengli

    2012-12-01

    The design and development of the miniaturized interferometer for measurement of the refractive index or concentration of sub-microliter volume aqueous solution in microfludic chip is presented. It is manifested by a successful measurement of the refractive index of sugar-water solution, by utilizing a laser diode for light source and the small robust instrumentation for practical implementation. Theoretically, the measurement principle and the feasibility of the system are analyzed. Experimental device is constructed with a diode laser, lens, two optical plate and a complementary metal oxide semiconductor (CMOS). Through measuring the positional changes of the interference fringes, the refractive index change are retrieved. A refractive index change of 10-4 is inferred from the measured image data. The entire system is approximately the size of half and a deck of cards and can operate on battery power for long time.

  7. Microfluidic chip-based synthesis of alginate microspheres for encapsulation of immortalized human cells

    PubMed Central

    Workman, V. L.; Dunnett, S. B.; Kille, P.; Palmer, D. D.

    2007-01-01

    Cellular transplantation is a promising technology with great clinical potential in regenerative medicine and disease management. However, effective control over patient immunological response is essential. The encapsulation of cells within hydrogel microspheres is an increasingly prevalent method for the protection of cellular grafts from immune rejection. Microfluidic “chip” reactors present elegant solutions to several capsule generation issues, including the requirement for intercapsule uniformity, high reproducibility, and sterile, good manufacturing practice compliance. This study presents a novel method for the on-chip production of stable, highly monodisperse alginate microspheres and demonstrates its utility in the encapsulation of an immortalized human-derived cell line. Four populations of immortalized human embryonic kidney cells (HEK293) were encapsulated on chip within monodisperse alginate capsules. Cell viability measurements were recorded for each of the four encapsulated populations for 90 days. PMID:19693354

  8. Microfluidic Devices for Terahertz Spectroscopy of Live Cells Toward Lab-on-a-Chip Applications.

    PubMed

    Tang, Qi; Liang, Min; Lu, Yi; Wong, Pak Kin; Wilmink, Gerald J; Zhang, Donna; Xin, Hao

    2016-04-04

    THz spectroscopy is an emerging technique for studying the dynamics and interactions of cells and biomolecules, but many practical challenges still remain in experimental studies. We present a prototype of simple and inexpensive cell-trapping microfluidic chip for THz spectroscopic study of live cells. Cells are transported, trapped and concentrated into the THz exposure region by applying an AC bias signal while the chip maintains a steady temperature at 37 °C by resistive heating. We conduct some preliminary experiments on E. coli and T-cell solution and compare the transmission spectra of empty channels, channels filled with aqueous media only, and channels filled with aqueous media with un-concentrated and concentrated cells.

  9. Acoustophoretic microfluidic chip for sequential elution of surface bound molecules from beads or cells

    PubMed Central

    Augustsson, Per; Malm, Johan; Ekström, Simon

    2012-01-01

    An acoustophoresis-based microfluidic flow-chip is presented as a novel platform to facilitate analysis of proteins and peptides loosely bound to the surface of beads or cells. The chip allows for direct removal of the background surrounding the beads or cells, followed by sequential treatment and collection of a sequence of up to five different buffer conditions. During this treatment, the beads/cells are retained in a single flow by acoustic radiation force. Eluted peptides are collected from the outlets and subsequently purified by miniaturized solid-phase extraction and analyzed with matrix assisted laser desorption mass spectrometry. Fundamental parameters such as the system fluidics and dispersion are presented. The device was successfully applied for wash and sequential elution of peptides bound to the surface of microbeads and human spermatozoa, respectively. PMID:24003343

  10. Microfluidic Devices for Terahertz Spectroscopy of Live Cells Toward Lab-on-a-Chip Applications

    PubMed Central

    Tang, Qi; Liang, Min; Lu, Yi; Wong, Pak Kin; Wilmink, Gerald J.; D. Zhang, Donna; Xin, Hao

    2016-01-01

    THz spectroscopy is an emerging technique for studying the dynamics and interactions of cells and biomolecules, but many practical challenges still remain in experimental studies. We present a prototype of simple and inexpensive cell-trapping microfluidic chip for THz spectroscopic study of live cells. Cells are transported, trapped and concentrated into the THz exposure region by applying an AC bias signal while the chip maintains a steady temperature at 37 °C by resistive heating. We conduct some preliminary experiments on E. coli and T-cell solution and compare the transmission spectra of empty channels, channels filled with aqueous media only, and channels filled with aqueous media with un-concentrated and concentrated cells. PMID:27049392

  11. Fabrication of microfluidic chips using lithographic patterning and adhesive bonding of the thick negative photoresist AZ 125 nXT

    NASA Astrophysics Data System (ADS)

    Knoll, Thorsten; Bergmann, Andreas; Nußbaum, Dominic

    2015-05-01

    In this work, for the first time the negative photoresist AZ 125 nXT was used for the fabrication of a microfluidic chip. Usually, fabrication of microfluidic devices on the basis of silicon or glass substrates is done by using the epoxy-based negative photoresist SU-8 or other thick film polymer materials. The suitability of SU-8 for various microfluidic applications has been shown in the fields of bioanalytic devices, lab-on-chip systems or microreaction technology. However, processing is always a very challenging task with regard to the adaptation of process parameters to the individual design and required functionality. Now, the AZ 125 nXT allows for the fabrication of structures in a wide thickness range with only one type of viscosity. In contrast to SU-8, the AZ 125 nXT is fully cross-linked during UV exposure and does not require a time-consuming post-exposure bake. 90 μm deep microfluidic channels were defined by lithographic patterning of AZ 125 nXT. Sealing of the open microfluidic channels was performed by a manual adhesive bonding process at a temperature of 100 °C. The fluidic function was successfully tested with flow rates up to 20 ml/min by means of a microfluidic edge connector. Long term stability and chemical resistance of the fabricated microfluidic channels will be investigated in the near future. The presented work shows the potential of AZ 125 nXT as a possible alternative to SU-8 for the fabrication of microfluidic chips.

  12. Novel microfluidic platform for automated lab-on-chip testing of hypercoagulability panel.

    PubMed

    Emani, Sirisha; Sista, Ramakrishna; Loyola, Hugo; Trenor, Cameron C; Pamula, Vamsee K; Emani, Sitaram M

    2012-12-01

    Current methods for hypercoagulability panel testing require large blood volumes and long turn-around testing times. A novel microfluidic platform has been designed to perform automated multiplexed hypercoagulability panel testing at near patient, utilizing only a single droplet of blood sample. We test the hypothesis that this novel platform could be utilized to perform specific multiplexed ELISA-based hypercoagulability panel testing for antithrombin III, protein C, protein S and factor VIII antigens, as well as anticardiolipin/human anti-β2-glycoprotein-1 IgG antibodies--on blood samples. Sandwich ELISA was modified by utilizing magnetic beads coated with specific antibodies as the solid phase using fluorescence readout. Percentage recovery was calculated using four-parameter logistic curves. On-chip ELISA with single factors was compared with multiplex factor ELISA for known concentrations of sample. Blood samples were analyzed on-chip and compared with traditional bench-top assays. Time for multiplexed performance of hypercoagulability panel ELISA on-chip with controls is 72 min. Recovery rates (range 80-120%) for known concentrations of specific factors was not significantly different when assays were performed using a single factor vs. multiplex factor analysis. Assay results were not significantly different between individual assays performed either on bench-top or on-chip with patient blood and/or plasma. Utilizing a novel digital microfluidic platform, we demonstrate the feasibility of automated hypercoagulability panel testing on small volume of plasma and whole blood patient samples with high fidelity. Further investigation is required to test the application of this novel technology at point-of-care clinical settings.

  13. Prototyping of thermoplastic microfluidic chips and their application in high-performance liquid chromatography separations of small molecules.

    PubMed

    Wouters, Sam; De Vos, Jelle; Dores-Sousa, José Luís; Wouters, Bert; Desmet, Gert; Eeltink, Sebastiaan

    2017-06-01

    The present paper discusses practical aspects of prototyping of microfluidic chips using cyclic olefin copolymer as substrate and the application in high-performance liquid chromatography. The developed chips feature a 60mm long straight separation channel with circular cross section (500μm i.d.) that was created using a micromilling robot. To irreversibly seal the top and bottom chip substrates, a solvent-vapor-assisted bonding approach was optimized, allowing to approximate the ideal circular channel geometry. Four different approaches to establish the micro-to-macro interface were pursued. The average burst pressure of the microfluidic chips in combination with an encasing holder was established at 38MPa and the maximum burst pressure was 47MPa, which is believed to be the highest ever report for these polymer-based microfluidic chips. Porous polymer monolithic frits were synthesized in-situ via UV-initiated polymerization and their locations were spatially controlled by the application of a photomask. Next, high-pressure slurry packing was performed to introduce 3μm silica reversed-phase particles as the stationary phase in the separation channel. Finally, the application of the chip technology is demonstrated for the separation of alkyl phenones in gradient mode yielding baseline peak widths of 6s by applying a steep gradient of 1.8min at a flow rate of 10μL/min. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. [An enzyme reactor based on aptamer modified microfluidic chip for protein analysis].

    PubMed

    Xiao, Peng; Li, Dalei; Man, Yan; Geng, Lina; Lü, Xuefei; Deng, Yulin

    2012-11-01

    As a kind of recognition molecule, aptamer has been studied and applied widely in numerous science fields in recent years. Immobilized enzymatic reactor has drawn much attention because of its striking advantages, such as high digestion efficiency and ease in coupling with the separation and detection systems. In this study, a novel microfluidic enzymatic chip, which immobilized trypsin based on aptamer, was prepared and proposed. An online analysis platform, which consisted of an aptamer-based chip and high performance liquid chromatography tandem mass spectrometry, was established by using a 6-port valve and applied to protein analysis. The enzymatic capacity and stability performance of chip reactor were characterized by using mixed protein sample, which consisted of bovine serum albumin (BSA), myoglobin (Mb) and cytochrome c (Cyt. c). The sample digestion time of the chip reactor was about 5.76 s while 1 microL/min of flow rate was adopted; and moreover, 5 ng of Mb was identified successfully with the sequence coverage of 37%. Furthermore, the sequence coverages and the relative standard deviations were 44.3% and 6.5% for BSA, 65.0% and 2.7% for Mb, 62.0% and 5.6% for Cyt. c respectively when 500 ng digest of mixed proteins were analyzed in three runs. According to experimental results, the online analysis platform possesses the ability of high sensitivity and good stability, which can provide a promising tool for rapid and high-throughput proteomics study in the near future.

  15. Tumour-on-a-chip: microfluidic models of tumour morphology, growth and microenvironment

    PubMed Central

    Trubelja, Alen

    2017-01-01

    Cancer remains one of the leading causes of death, albeit enormous efforts to cure the disease. To overcome the major challenges in cancer therapy, we need to have a better understanding of the tumour microenvironment (TME), as well as a more effective means to screen anti-cancer drug leads; both can be achieved using advanced technologies, including the emerging tumour-on-a-chip technology. Here, we review the recent development of the tumour-on-a-chip technology, which integrates microfluidics, microfabrication, tissue engineering and biomaterials research, and offers new opportunities for building and applying functional three-dimensional in vitro human tumour models for oncology research, immunotherapy studies and drug screening. In particular, tumour-on-a-chip microdevices allow well-controlled microscopic studies of the interaction among tumour cells, immune cells and cells in the TME, of which simple tissue cultures and animal models are not amenable to do. The challenges in developing the next-generation tumour-on-a-chip technology are also discussed. PMID:28637915

  16. All inkjet-printed electroactive polymer actuators for microfluidic lab-on-chip systems

    NASA Astrophysics Data System (ADS)

    Pabst, Oliver; Beckert, Erik; Perelaer, Jolke; Schubert, Ulrich S.; Eberhardt, Ramona; Tünnermann, Andreas

    2013-04-01

    Piezoelectric electroactive polymers (EAP) are promising materials for applications in microfluidic lab-on-chip systems. In such systems, fluids can be analyzed by different chemical or physical methods. During the analysis the fluids need to be distributed through the channels of the chip, which requires a pumping function. We present here all inkjet-printed EAP actuators that can be configured as a membrane-based micropump suitable for direct integration into lab-on-chip systems. Drop-on-demand inkjet printing is a versatile digital deposition technique that is capable of depositing various functional materials onto a wide variety of substrates in an additive way. Compared to conventional lithography-based processing it is cost-efficient and flexible, as no masking is required. The actuators consist of a polymer foil substrate with an inkjet-printed EAP layer sandwiched between a set of two electrodes. The actuators are printed using a commercially available EAP solution and silver nanoparticle inks. When a voltage is applied across the polymer layer, piezoelectric strain leads to a bending deflection of the beam or membrane. Circular membrane actuators with 20 mm diameter and EAP thicknesses of 10 to 15 μm exhibit deflections of several μm when driven at their resonance frequency with voltages of 110 V. From the behavior of membrane actuators a pumping rate of several 100 μL/min can be estimated, which is promising for applications in lab-on-chip devices.

  17. Fabrication of a polystyrene microfluidic chip coupled to electrospray ionization mass spectrometry for protein analysis.

    PubMed

    Hu, Xianqiao; Dong, Yuanyuan; He, Qiaohong; Chen, Hengwu; Zhu, Zhiwei

    2015-05-15

    A highly integrated polystyrene (PS) microfluidic chip coupled to electrospray ionization mass spectrometry for on-chip protein digestion and online analysis was developed. The immobilized enzymatic microreactor for on-chip protein digestion was integrated onto microchip via the novel method of region-selective UV-modification combined with glutaraldehyde-based immobilization. The micro film electric contact for applying high voltage was prepared on chips by using UV-directed electroless plating technique. A micro-tip was machined at the end of main channel, serving as the interface between microchip and mass spectrometric detector. On-chip digestion and online detection of protein was carried out by coupling the microchip with mass spectrometry (MS). The influences of methanol flow rate in side channel on the stability of spray and intensity of signals were investigated systematically. Also the influence of sample flow rate on the performance of immobilized enzymatic reactor were investigated. Stable spray was obtained at the spray voltage of 2.8-3.0kV and the methanol flow rate of 500-700nLmin(-1) with the relative standard deviation (RSD) of total ion current (TIC) less than 10%. The influence of sample flow rate on the performance of immobilized enzymatic reactor was also studied. The sequence coverage of protein identification decreased with the increase of flow rate of the sample solution. A sequence coverage of 96% was obtained with immobilized enzymatic reactor at the sample flow rate of 100nLmin(-1) with the reaction time of 8.4min. It could detect cytochrome c as low as 10μgmL(-1) with the developed system. No obvious decrease in protein digestion efficiency was observed after the chip continuously performed for 4h and stored for 15d. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Microfluidic Arrayed Lab-On-A-Chip for Electrochemical Capacitive Detection of DNA Hybridization Events.

    PubMed

    Ben-Yoav, Hadar; Dykstra, Peter H; Bentley, William E; Ghodssi, Reza

    2017-01-01

    A microfluidic electrochemical lab-on-a-chip (LOC) device for DNA hybridization detection has been developed. The device comprises a 3 × 3 array of microelectrodes integrated with a dual layer microfluidic valved manipulation system that provides controlled and automated capabilities for high throughput analysis of microliter volume samples. The surface of the microelectrodes is functionalized with single-stranded DNA (ssDNA) probes which enable specific detection of complementary ssDNA targets. These targets are detected by a capacitive technique which measures dielectric variation at the microelectrode-electrolyte interface due to DNA hybridization events. A quantitative analysis of the hybridization events is carried out based on a sensing modeling that includes detailed analysis of energy storage and dissipation components. By calculating these components during hybridization events the device is able to demonstrate specific and dose response sensing characteristics. The developed microfluidic LOC for DNA hybridization detection offers a technology for real-time and label-free assessment of genetic markers outside of laboratory settings, such as at the point-of-care or in-field environmental monitoring.

  19. Continuous Flow 1H and 13C NMR Spectroscopy in Microfluidic Stripline NMR Chips

    PubMed Central

    2017-01-01

    Microfluidic stripline NMR technology not only allows for NMR experiments to be performed on small sample volumes in the submicroliter range, but also experiments can easily be performed in continuous flow because of the stripline’s favorable geometry. In this study we demonstrate the possibility of dual-channel operation of a microfluidic stripline NMR setup showing one- and two-dimensional 1H, 13C and heteronuclear NMR experiments under continuous flow. We performed experiments on ethyl crotonate and menthol, using three different types of NMR chips aiming for straightforward microfluidic connectivity. The detection volumes are approximately 150 and 250 nL, while flow rates ranging from 0.5 μL/min to 15 μL/min have been employed. We show that in continuous flow the pulse delay is determined by the replenishment time of the detector volume, if the sample trajectory in the magnet toward NMR detector is long enough to polarize the spin systems. This can considerably speed up quantitative measurement of samples needing signal averaging. So it can be beneficial to perform continuous flow measurements in this setup for analysis of, e.g., reactive, unstable, or mass-limited compounds. PMID:28194934

  20. Continuous Flow (1)H and (13)C NMR Spectroscopy in Microfluidic Stripline NMR Chips.

    PubMed

    Oosthoek-de Vries, Anna Jo; Bart, Jacob; Tiggelaar, Roald M; Janssen, Johannes W G; van Bentum, P Jan M; Gardeniers, Han J G E; Kentgens, Arno P M

    2017-02-21

    Microfluidic stripline NMR technology not only allows for NMR experiments to be performed on small sample volumes in the submicroliter range, but also experiments can easily be performed in continuous flow because of the stripline's favorable geometry. In this study we demonstrate the possibility of dual-channel operation of a microfluidic stripline NMR setup showing one- and two-dimensional (1)H, (13)C and heteronuclear NMR experiments under continuous flow. We performed experiments on ethyl crotonate and menthol, using three different types of NMR chips aiming for straightforward microfluidic connectivity. The detection volumes are approximately 150 and 250 nL, while flow rates ranging from 0.5 μL/min to 15 μL/min have been employed. We show that in continuous flow the pulse delay is determined by the replenishment time of the detector volume, if the sample trajectory in the magnet toward NMR detector is long enough to polarize the spin systems. This can considerably speed up quantitative measurement of samples needing signal averaging. So it can be beneficial to perform continuous flow measurements in this setup for analysis of, e.g., reactive, unstable, or mass-limited compounds.

  1. Temperature-controlled MPa-pressure ultrasonic cell manipulation in a microfluidic chip.

    PubMed

    Ohlin, Mathias; Iranmanesh, Ida; Christakou, Athanasia E; Wiklund, Martin

    2015-08-21

    We study the temperature-independent impact on cell viability of relevant physical parameters during long-term, high-acoustic-pressure ultrasonic exposure in a microfluidic chip designed for ultrasonic-standing-wave trapping and aggregation of cells. We use a light-intensity method and 5 μm polymer beads for accurate acoustic pressure calibration before injecting cells into the device, and we monitor the viability of A549 lung cancer cells trapped during one hour in an ultrasonic standing wave with 1 MPa pressure amplitude. The microfluidic chip is actuated by a novel temperature-controlled ultrasonic transducer capable of keeping the temperature stable around 37 °C with an accuracy better than ±0.2 °C, independently on the ultrasonic power and heat produced by the system, thereby decoupling any temperature effect from other relevant effects on cells caused by the high-pressure acoustic field. We demonstrate that frequency-modulated ultrasonic actuation can produce acoustic pressures of equally high magnitudes as with single-frequency actuation, and we show that A549 lung cancer cells can be exposed to 1 MPa standing-wave acoustic pressure amplitudes for one hour without compromising cell viability. At this pressure level, we also measure the acoustic streaming induced around the trapped cell aggregate, and conclude that cell viability is not affected by streaming velocities of the order of 100 μm s(-1). Our results are important when implementing acoustophoresis methods in various clinical and biomedical applications.

  2. Surface Roughness Study on Microchannels of CO2 Laser Fabricating Pmma-Based Microfluidic Chip

    NASA Astrophysics Data System (ADS)

    Chen, Xueye; Li, Tiechuan; Fu, Baoding

    A novel method named soak sacrificial layer ultrasonic method (SSLUM) has been presented for optimizing the surface roughness of the microchannels of polymethyl methacrylate (PMMA)-based microfluidic chips. CO2 laser was used for ablative microchannels on the PMMA sheet, and the effects of key parameters including laser power, laser ablation speed and solution concentration on the surface roughness of microchannels were estimated and optimized by SSLUM. The experimental observation demonstrates that the surface roughness results mainly from the residues on the channel wall, which are produced by the bubbles movement and bursting. The research results show that the surface roughness can be improved effectively by using SSLUM. In our experiment, the best value was Ra = 110nm with laser power 12W, laser ablation speed 10mm/s, the solution concentration 75%, and the time of ultrasonic vibration 25min. SSLUM is proven to be an effective, simple and rapid method for optimizing the surface roughness of microchannels of microfluidic chips.

  3. Microfluidic integration of wirebonded microcoils for on-chip applications in nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Meier, Robert Ch; Höfflin, Jens; Badilita, Vlad; Wallrabe, Ulrike; Korvink, Jan G.

    2014-04-01

    We present an integrated microfluidic device for on-chip nuclear magnetic resonance (NMR) studies of microscopic samples. The devices are fabricated by means of a MEMS compatible process, which joins the automatic wirebond winding of solenoidal microcoils and the manufacturing of a complex microfluidic network using dry-photoresist lamination. The wafer-scale cleanroom process is potentially capable of mass fabrication. Since the non-invasive NMR analysis technique is rather insensitive, particularly when microscopic sample volumes are to be investigated, we also focus on the optimization of the wirebonded microcoil for this purpose. The on-chip measurement of NMR signals from a 20 nl sample are evaluated for imaging analysis of microparticles, as well as for spectroscopy. Whereas the latter revealed that the sensitivity of the MEMS microcoil is comparable with hand-wound devices and achieves a full-width-half-maximum linewidth of 8 Hz, the imaging experiment demonstrated 10 μm isotropic spatial resolution within an experiment time of 38 min for a 3D image with a field of view of 1 mm × 1 mm × 0.5 mm (500 000 voxels).

  4. A microfluidic device for on-chip agarose microbead generation with ultralow reagent consumption

    PubMed Central

    Desbois, Linda; Padirac, Adrien; Kaneda, Shohei; Genot, Anthony J.; Rondelez, Yannick; Hober, Didier; Collard, Dominique; Fujii, Teruo

    2012-01-01

    Water-in-oil microdroplets offer microreactors for compartmentalized biochemical reactions with high throughput. Recently, the combination with a sol-gel switch ability, using agarose-in-oil microdroplets, has increased the range of possible applications, allowing for example the capture of amplicons in the gel phase for the preservation of monoclonality during a PCR reaction. Here, we report a new method for generating such agarose-in-oil microdroplets on a microfluidic device, with minimized inlet dead volume, on-chip cooling, and in situ monitoring of biochemical reactions within the gelified microbeads. We used a flow-focusing microchannel network and successfully generated agarose microdroplets at room temperature using the “push-pull” method. This method consists in pushing the oil continuous phase only, while suction is applied to the device outlet. The agarose phase present at the inlet is thus aspirated in the device, and segmented in microdroplets. The cooling system consists of two copper wires embedded in the microfluidic device. The transition from agarose microdroplets to microbeads provides additional stability and facilitated manipulation. We demonstrate the potential of this method by performing on-chip a temperature-triggered DNA isothermal amplification in agarose microbeads. Our device thus provides a new way to generate microbeads with high throughput and no dead volume for biochemical applications. PMID:24106525

  5. Recent advancements in chemical luminescence-based lab-on-chip and microfluidic platforms for bioanalysis.

    PubMed

    Mirasoli, Mara; Guardigli, Massimo; Michelini, Elisa; Roda, Aldo

    2014-01-01

    Miniaturization of analytical procedures through microchips, lab-on-a-chip or micro total analysis systems is one of the most recent trends in chemical and biological analysis. These systems are designed to perform all the steps in an analytical procedure, with the advantages of low sample and reagent consumption, fast analysis, reduced costs, possibility of extra-laboratory application. A range of detection technologies have been employed in miniaturized analytical systems, but most applications relied on fluorescence and electrochemical detection. Chemical luminescence (which includes chemiluminescence, bioluminescence, and electrogenerated chemiluminescence) represents an alternative detection principle that offered comparable (or better) analytical performance and easier implementation in miniaturized analytical devices. Nevertheless, chemical luminescence-based ones represents only a small fraction of the microfluidic devices reported in the literature, and until now no review has been focused on these devices. Here we review the most relevant applications (since 2009) of miniaturized analytical devices based on chemical luminescence detection. After a brief overview of the main chemical luminescence systems and of the recent technological advancements regarding their implementation in miniaturized analytical devices, analytical applications are reviewed according to the nature of the device (microfluidic chips, microchip electrophoresis, lateral flow- and paper-based devices) and the type of application (micro-flow injection assays, enzyme assays, immunoassays, gene probe hybridization assays, cell assays, whole-cell biosensors). Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Microfluidic positioning of pollen grains in lab-on-a-chip for single cell analysis.

    PubMed

    Ghanbari, Mahmood; Nezhad, Amir Sanati; Agudelo, Carlos G; Packirisamy, Muthukumaran; Geitmann, Anja

    2014-04-01

    A lab-on-a-chip device with a knot shaped microfluidic network is presented to enable trapping of single pollen grains at the entrances of a series of microchannels. This set-up serves to create identical growth conditions for serially arranged tip growing plant cells such as pollen tubes. The design consists of an inlet to introduce the pollen suspension into the chip, three outlets to evacuate excess medium or cells, a distribution chamber to guide the pollen grains toward the growth microchannels and a serial arrangement of microchannels with different geometries connected to the distribution chamber. These microchannels are to harbor the individual pollen tubes. Two different criteria were established to assess the efficiency and optimize the device: trapping probability and uniformity of fluid flow conditions within the microchannels. The performance of different geometries of the microfluidic network was numerically analyzed and experimentally tested. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  7. A microfluidic device for on-chip agarose microbead generation with ultralow reagent consumption.

    PubMed

    Desbois, Linda; Padirac, Adrien; Kaneda, Shohei; Genot, Anthony J; Rondelez, Yannick; Hober, Didier; Collard, Dominique; Fujii, Teruo

    2012-01-01

    Water-in-oil microdroplets offer microreactors for compartmentalized biochemical reactions with high throughput. Recently, the combination with a sol-gel switch ability, using agarose-in-oil microdroplets, has increased the range of possible applications, allowing for example the capture of amplicons in the gel phase for the preservation of monoclonality during a PCR reaction. Here, we report a new method for generating such agarose-in-oil microdroplets on a microfluidic device, with minimized inlet dead volume, on-chip cooling, and in situ monitoring of biochemical reactions within the gelified microbeads. We used a flow-focusing microchannel network and successfully generated agarose microdroplets at room temperature using the "push-pull" method. This method consists in pushing the oil continuous phase only, while suction is applied to the device outlet. The agarose phase present at the inlet is thus aspirated in the device, and segmented in microdroplets. The cooling system consists of two copper wires embedded in the microfluidic device. The transition from agarose microdroplets to microbeads provides additional stability and facilitated manipulation. We demonstrate the potential of this method by performing on-chip a temperature-triggered DNA isothermal amplification in agarose microbeads. Our device thus provides a new way to generate microbeads with high throughput and no dead volume for biochemical applications.

  8. Ultrasmall volume molecular isothermal amplification in microfluidic chip with advanced surface processing

    NASA Astrophysics Data System (ADS)

    Huang, Guoliang; Ma, Li; Yang, Xiaoyong; Yang, Xu

    2011-01-01

    In this paper, we developed a metal micro-fluidic chip with advanced surface processing for ultra-small volume molecular isothermal amplification. This method takes advantages of the nucleic acid amplification with good stability and consistency, high sensitivity about 31 genomic DNA copies and bacteria specific gene identification. Based on the advanced surface processing, the bioreaction assays of nucleic acid amplification was dropped about 392nl in volume. A high numerical aperture confocal optical detection system was advanced to sensitively monitor the DNA amplification with low noise and high power collecting fluorescence near to the optical diffraction limit. A speedy nucleic acid isothermal amplification was performed in the ultra-small volume microfluidic chip, where the time at the inflexions of second derivative to DNA exponential amplified curves was brought forward and the sensitivity was improved about 65 folds to that of in current 25μl Ep-tube amplified reaction, which indicates a promising clinic molecular diagnostics in the droplet amplification.

  9. Optimization of a Thermal Lens Microscope for Detection in a Microfluidic Chip

    NASA Astrophysics Data System (ADS)

    Liu, Mingqiang; Novak, Uroš; Plazl, Igor; Franko, Mladen

    2014-11-01

    The optical configuration of a thermal lens microscope (TLM) was optimized for detection in a microfluidic chip with respect to the flow velocity, and the pump and probe beam parameters (beam waists, offsets, and mode mismatching degree). It was found that an appropriate pump-probe beam offset for a certain flow velocity would provide not only a higher sensitivity but also a better response linearity of TLM over three orders of magnitude of sample concentration. Diffraction-limited pump beam excitation is advantageous for space-resolved measurement, while a larger pump beam with 10 times lower power density is favorable for higher sensitivity at given experimental conditions. As an application, TLM was used to study the diffusion of azobenzene in a microfluidic chip. Diffusion profiles at different distances from the mixing point were recorded by scanning the TL signal along the cross section of the microchannel. By fitting the diffusion profiles to a theoretical model of mass transfer in a microchannel, diffusion coefficients of azobenzene in octane and methanol were determined to be and , respectively.

  10. Detection of DNAs by Using Dual Packed Polystyrene Bead-Quantum Dots in a Microfluidic Chip.

    PubMed

    Le, Ngoc Tam; Kim, Jong Sung

    2015-01-01

    The semiconductor nanocrystals (or quantum dots) have shown peculiar optical and electrical properties due to their exceptionally small size. In recent years, tremendous researches on quantum dots have been carried out. Among them, QDs as sensing media for biological assay have achieved a great progress. Recently we have reported the detection of DNAs by using fluorescence quenching of QDs after DNA hybridization. Several oligonucleotides and human genomic genes could be detected. In this report we used dual packing of polystyrene bead-quantum dots to detect different kinds of DNAs simultaneously. QDs with different emission peaks were used. Carboxylated-CdSe/ZnS QDs (emission: 525, 605 nm) could bind to microbeads of polystyrene/divinyl benzene via EDC/NHS cross-linking reaction. Polystyrene bead-QDs with different colors were packed in the channel of the microfluidic chip. The fluorescence quenching from the QDs by intercalating dye was observed after hybridization of exon 6 and 7 of p53 gene at the weir in the channel of microfluidic chip. The simultaneous fluorescence quenching of the QDs by PI and TOTO-3 were observed.

  11. A Butyl Methacrylate Monolithic Column Prepared In-Situ on a Microfluidic Chip and its Applications

    PubMed Central

    Xu, Yi; Zhang, Wenpin; Zeng, Ping; Cao, Qiang

    2009-01-01

    A butyl methacrylate (BMA) monolithic column was polymerized in-situ with UV irradiation in an ultraviolet transparent PDMS micro-channel on a homemade micro-fluidic chip. Under the optimized conditions and using a typical polymerization mixture consisting of 75% porogenic solvents and 25% monomers, the BMA monolithic column was obtained as expected. The BET surface area ratio of the BMA monolithic column was 366 m2·g-1. The corresponding SEM images showed that the monolithic column material polymerized in a glass channel was composed of uniform pores and spherical particles with diameters ranging from 3 to 5 μm. The promethazine–luminal–potassium ferricyanide chemiluminescence system was selected for testing the capability of the column. A flow injection analytical technique–chemiluminescence (FIA–CL) system on the microfluidic chip with a BMA monolithic column pretreatment unit was established to determine promethazine. Trace promethazine was enriched by the BMA monolithic column, with more than a 10-fold average enrichment ratio. The proposed method has a linear response concentration range of 1.0×10-8 - 1.0×10-6g·mL-1 and the detection limit was 1.6×10-9g·mL-1. PMID:22412320

  12. Soil-on-a-Chip: microfluidic platforms for environmental organismal studies.

    PubMed

    Stanley, Claire E; Grossmann, Guido; i Solvas, Xavier Casadevall; deMello, Andrew J

    2016-01-21

    Soil is the habitat of countless organisms and encompasses an enormous variety of dynamic environmental conditions. While it is evident that a thorough understanding of how organisms interact with the soil environment may have substantial ecological and economical impact, current laboratory-based methods depend on reductionist approaches that are incapable of simulating natural diversity. The application of Lab-on-a-Chip or microfluidic technologies to organismal studies is an emerging field, where the unique benefits afforded by system miniaturisation offer new opportunities for the experimentalist. Indeed, precise spatiotemporal control over the microenvironments of soil organisms in combination with high-resolution imaging has the potential to provide an unprecedented view of biological events at the single-organism or single-cell level, which in turn opens up new avenues for environmental and organismal studies. Herein we review some of the most recent and interesting developments in microfluidic technologies for the study of soil organisms and their interactions with the environment. We discuss how so-called "Soil-on-a-Chip" technology has already contributed significantly to the study of bacteria, nematodes, fungi and plants, as well as inter-organismal interactions, by advancing experimental access and environmental control. Most crucially, we highlight where distinct advantages over traditional approaches exist and where novel biological insights will ensue.

  13. The Evopopbot Chip: Ultra High-throughput Evolutionary Population Bottlenecking using Drop-Based Microfluidics

    NASA Astrophysics Data System (ADS)

    Chang, Connie; Rotem, Assaf; Serohijos, Adrian; Zhang, Huidan; Tao, Ye; Fischer Hesselbrock, Audrey; Thielen, Peter; Mehoke, Thomas; Wolfe, Joshua; Wobus, Christiane; Feldman, Andrew; Shakhnovich, Eugene; Weitz, David

    2014-03-01

    The study of how viruses propagate is important for curing disease and preventing viral outbreaks. In nature, viruses can compete with one another, and the most evolutionary fit virus usually takes over a population. Yet there exist variants in the population that can escape subjected evolutionary pressures and eventually dominate the population. Successful studies of viral epidemics hinges on the ability to access these variants. Here, we present the use of droplet-based microfluidics as a simple method to segregate and propagate a viral population as individual viral lineages, simultaneously performing millions of in vitroevolutionary bottlenecking experiments. We introduce a novel microfluidic device, called the ``Evopopbot Chip'', that allows for simultaneous passaging of millions of evolutionary bottlenecking events by splitting drops containing previous generations of viruses and merging with drops containing new host cells. After several generations of viral replication in the evolution chip, we discover hundreds of new viruses that are able to escape a neutralizing antibody selection pressure compared to bulk passaging.

  14. Hot embossed polyethylene through-hole chips for bead-based microfluidic devices

    PubMed Central

    Chou, Jie; Du, Nan; Ou, Tina; Floriano, Pierre N.; Christodoulides, Nicolaos; McDevitt, John T.

    2013-01-01

    Over the past decade, there has been a growth of interest in the translation of microfluidic systems into real-world clinical practice, especially for use in point-of-care or near patient settings. While initial fabrication advances in microfluidics involved mainly the etching of silicon and glass, the economics of scaling of these materials is not amendable for point-of-care usage where single-test applications forces cost considerations to be kept low and throughput high. As such, a materials base more consistent with point-of-care needs is required. In this manuscript, the fabrication of a hot embossed, through-hole low-density polyethylene ensembles derived from an anisotropically etched silicon wafer is discussed. This semi-opaque polymer that can be easily sterilized and recycled provides low background noise for fluorescence measurements and yields more affordable cost than other thermoplastics commonly used for microfluidic applications such as cyclic olefin copolymer (COC). To fabrication through-hole microchips from this alternative material for microfluidics, a fabrication technique that uses a high-temperature, high-pressure resistant mold is described. This aluminum-based epoxy mold, serving as the positive master mold for embossing, is casted over etched arrays of pyramidal pits in a silicon wafer. Methods of surface treatment of the wafer prior to casting and PDMS casting of the epoxy are discussed to preserve the silicon wafer for future use. Changes in the thickness of polyethylene are observed for varying embossing temperatures. The methodology described herein can quickly fabricate 20 disposable, single use chips in less than 30 minutes with the ability to scale up 4x by using multiple molds simultaneously. When coupled as a platform supporting porous bead sensors, as in the recently developed Programmable Bio-Nano-Chip, this bead chip system can achieve limits of detection, for the cardiac biomarker C-reactive protein, of 0.3 ng/mL, thereby

  15. Hot embossed polyethylene through-hole chips for bead-based microfluidic devices.

    PubMed

    Chou, Jie; Du, Nan; Ou, Tina; Floriano, Pierre N; Christodoulides, Nicolaos; McDevitt, John T

    2013-04-15

    Over the past decade, there has been a growth of interest in the translation of microfluidic systems into real-world clinical practice, especially for use in point-of-care or near patient settings. While initial fabrication advances in microfluidics involved mainly the etching of silicon and glass, the economics of scaling of these materials is not amendable for point-of-care usage where single-test applications force cost considerations to be kept low and throughput high. As such, materials base more consistent with point-of-care needs is required. In this manuscript, the fabrication of a hot embossed, through-hole low-density polyethylene ensembles derived from an anisotropically etched silicon wafer is discussed. This semi-opaque polymer that can be easily sterilized and recycled provides low background noise for fluorescence measurements and yields more affordable cost than other thermoplastics commonly used for microfluidic applications such as cyclic olefin copolymer (COC). To fabrication through-hole microchips from this alternative material for microfluidics, a fabrication technique that uses a high-temperature, high-pressure resistant mold is described. This aluminum-based epoxy mold, serving as the positive master mold for embossing, is casted over etched arrays of pyramidal pits in a silicon wafer. Methods of surface treatment of the wafer prior to casting and PDMS casting of the epoxy are discussed to preserve the silicon wafer for future use. Changes in the thickness of polyethylene are observed for varying embossing temperatures. The methodology described herein can quickly fabricate 20 disposable, single use chips in less than 30 min with the ability to scale up 4 times by using multiple molds simultaneously. When coupled as a platform supporting porous bead sensors, as in the recently developed Programmable Bio-Nano-Chip, this bead chip system can achieve limits of detection, for the cardiac biomarker C-reactive protein, of 0.3 ng/mL, thereby

  16. An integrated sample-in-answer-out microfluidic chip for rapid human identification by STR analysis.

    PubMed

    Le Roux, Delphine; Root, Brian E; Hickey, Jeffrey A; Scott, Orion N; Tsuei, Anchi; Li, Jingyi; Saul, David J; Chassagne, Luc; Landers, James P; de Mazancourt, Philippe

    2014-11-21

    A fully integrated microfluidic chip for human identification by short tandem repeat (STR) analysis that includes a unique enzymatic liquid preparation of the DNA, microliter non-contact PCR, and a polymer that allows a high-resolution separation within a compact microchip footprint has been developed. A heat-activated enzyme that digests biological materials is employed to generate the target yield of DNA from a buccal swab or FTA paper. The microfluidic architecture meters an aliquot of the liberated DNA and mixes it with the PCR reagents prior to non-contact IR-mediated PCR amplification. The products of PCR amplification are mixed with a sizing standard (ladder) and the 18-plex STR amplicons are separated in an effective length (Leff) of just 7 cm. The development, optimization and integration of each of these processes within the microfluidic chip are described. The device is able to generate genetic profiles in approximately 2 hours that match the profiles from the conventional processes performed using separate conventional instruments. Analysis is performed on a single plastic microchip with a size similar to that of a 96-well plate and only a few mm thick with no pretreatment of any of the functional domains. This is significant advancement in terms of ease of fabrication over glass microdevices or polymeric systems assembled from multiple components. Consequently, this fully integrated sample-in-answer-out microchip is an important step toward generation of a rapid micro-total analysis system for point-of-collection human identification based on genetic analysis.

  17. Self-digitization microfluidic chip for absolute quantification of mRNA in single cells.

    PubMed

    Thompson, Alison M; Gansen, Alexander; Paguirigan, Amy L; Kreutz, Jason E; Radich, Jerald P; Chiu, Daniel T

    2014-12-16

    Quantification of mRNA in single cells provides direct insight into how intercellular heterogeneity plays a role in disease progression and outcomes. Quantitative polymerase chain reaction (qPCR), the current gold standard for evaluating gene expression, is insufficient for providing absolute measurement of single-cell mRNA transcript abundance. Challenges include difficulties in handling small sample volumes and the high variability in measurements. Microfluidic digital PCR provides far better sensitivity for minute quantities of genetic material, but the typical format of this assay does not allow for counting of the absolute number of mRNA transcripts samples taken from single cells. Furthermore, a large fraction of the sample is often lost during sample handling in microfluidic digital PCR. Here, we report the absolute quantification of single-cell mRNA transcripts by digital, one-step reverse transcription PCR in a simple microfluidic array device called the self-digitization (SD) chip. By performing the reverse transcription step in digitized volumes, we find that the assay exhibits a linear signal across a wide range of total RNA concentrations and agrees well with standard curve qPCR. The SD chip is found to digitize a high percentage (86.7%) of the sample for single-cell experiments. Moreover, quantification of transferrin receptor mRNA in single cells agrees well with single-molecule fluorescence in situ hybridization experiments. The SD platform for absolute quantification of single-cell mRNA can be optimized for other genes and may be useful as an independent control method for the validation of mRNA quantification techniques.

  18. BBB on chip: microfluidic platform to mechanically and biochemically modulate blood-brain barrier function.

    PubMed

    Griep, L M; Wolbers, F; de Wagenaar, B; ter Braak, P M; Weksler, B B; Romero, I A; Couraud, P O; Vermes, I; van der Meer, A D; van den Berg, A

    2013-02-01

    The blood-brain barrier (BBB) is a unique feature of the human body, preserving brain homeostasis and preventing toxic substances to enter the brain. However, in various neurodegenerative diseases, the function of the BBB is disturbed. Mechanisms of the breakdown of the BBB are incompletely understood and therefore a realistic model of the BBB is essential. We present here the smallest model of the BBB yet, using a microfluidic chip, and the immortalized human brain endothelial cell line hCMEC/D3. Barrier function is modulated both mechanically, by exposure to fluid shear stress, and biochemically, by stimulation with tumor necrosis factor alpha (TNF-α), in one single device. The device has integrated electrodes to analyze barrier tightness by measuring the transendothelial electrical resistance (TEER). We demonstrate that hCMEC/D3 cells could be cultured in the microfluidic device up to 7 days, and that these cultures showed comparable TEER values with the well-established Transwell assay, with an average (± SEM) of 36.9 Ω.cm(2) (± 0.9 Ω.cm(2)) and 28.2 Ω.cm(2) (± 1.3 Ω.cm(2)) respectively. Moreover, hCMEC/D3 cells on chip expressed the tight junction protein Zonula Occludens-1 (ZO-1) at day 4. Furthermore, shear stress positively influenced barrier tightness and increased TEER values with a factor 3, up to 120 Ω.cm(2). Subsequent addition of TNF-α decreased the TEER with a factor of 10, down to 12 Ω.cm(2). This realistic microfluidic platform of the BBB is very well suited to study barrier function in detail and evaluate drug passage to finally gain more insight into the treatment of neurodegenerative diseases.

  19. Microfluidic Chip for Molecular Amplification of Influenza A RNA in Human Respiratory Specimens

    PubMed Central

    Chang, Jessie; Carey, Brendan; Hsieh, Christopher; Stanley, Ahjegannie; Odell, Christine A.; Mitchell, Patricia; Feldman, James; Pollock, Nira R.; Klapperich, Catherine M.

    2012-01-01

    A rapid, low cost, accurate point-of-care (POC) device to detect influenza virus is needed for effective treatment and control of both seasonal and pandemic strains. We developed a single-use microfluidic chip that integrates solid phase extraction (SPE) and molecular amplification via a reverse transcription polymerase chain reaction (RT-PCR) to amplify influenza virus type A RNA. We demonstrated the ability of the chip to amplify influenza A RNA in human nasopharyngeal aspirate (NPA) and nasopharyngeal swab (NPS) specimens collected at two clinical sites from 2008–2010. The microfluidic test was dramatically more sensitive than two currently used rapid immunoassays and had high specificity that was essentially equivalent to the rapid assays and direct fluorescent antigen (DFA) testing. We report 96% (CI 89%,99%) sensitivity and 100% (CI 95%,100%) specificity compared to conventional (bench top) RT-PCR based on the testing of n = 146 specimens (positive predictive value = 100%(CI 94%,100%) and negative predictive value = 96%(CI 88%,98%)). These results compare well with DFA performed on samples taken during the same time period (98% (CI 91%,100%) sensitivity and 96%(CI 86%,99%) specificity compared to our gold standard testing). Rapid immunoassay tests on samples taken during the enrollment period were less reliable (49%(CI 38%,61%) sensitivity and 98%(CI 98%,100%) specificity). The microfluidic test extracted and amplified influenza A RNA directly from clinical specimens with viral loads down to 103 copies/ml in 3 h or less. The new test represents a major improvement over viral culture in terms of turn around time, over rapid immunoassay tests in terms of sensitivity, and over bench top RT-PCR and DFA in terms of ease of use and portability. PMID:22457740

  20. Microfluidic lab-on-a-chip derivatization for gaseous carbonyl analysis.

    PubMed

    Pang, Xiaobing; Lewis, Alastair C; Ródenas-García, Milagros

    2013-06-28

    We present a microfluidic lab-on-a-chip derivatization technique for the analysis of gaseous carbonyl compounds using O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBHA) as the derivatizing reagent. The novel microfluidic lab-on-a-chip derivatization technique has been developed to measure nmol per mole (ppbv) mixing ratios of gaseous carbonyl compounds, which are of particular importance to atmospheric chemistry. The technique utilised a planar glass microreactor comprising three inlets and one outlet, gas and fluid splitting and combining channels, mixing junctions, and a 2.0m long, 620μm internal diameter reaction microchannel. The microreactor integrated three functions, providing: (1) a gas and liquid mixer and reactor, (2) reagent heating, and (3) sample pre-concentration. The concentration of derivatization solution, the volumetric flow rates of the incoming gas sample and PFBHA solution, and the temperature of the microreactor were optimised to achieve a near real-time measurement. The enhanced phase contact area-to-volume ratio and the high heat transfer rate in the microreactor resulted in a fast and high efficiency derivatization reaction, generating an effluent stream which was ready for direct introduction to GC-MS. Good linearity was observed for eight carbonyl compounds over the measurement ranges of 1-500ppbv when they were derivatized under optimal reaction conditions. The method detection limits (MDLs) were below 0.10nmolmol(-1) for most carbonyls in this study, which is below or close to their typical concentrations in clean ambient air. The performance of the technique was assessed by applying the methodology to the quantification of glyoxal (GLY) and methylglyoxal (MGLY) formed during isoprene photo-oxidation in an outdoor photoreactor chamber (EUPHORE). Good agreements between GLY and MGLY measurements were obtained comparing this new technique with Fourier Transform InfraRed (FTIR), which provides support for the potential effectiveness of

  1. Detection of influenza virus using a lateral flow immunoassay for amplified DNA by a microfluidic RT-PCR chip.

    PubMed

    Nagatani, Naoki; Yamanaka, Keiichiro; Ushijima, Hiromi; Koketsu, Ritsuko; Sasaki, Tadahiro; Ikuta, Kazuyoshi; Saito, Masato; Miyahara, Toshiro; Tamiya, Eiichi

    2012-08-07

    Influenza virus RNA was amplified by a continuous-flow polydimethylsiloxane microfluidic RT-PCR chip within 15-20 min. The amplified influenza virus RNA was observed with the naked eye, as the red color at the test line, using a lateral flow immunoassay within 1 min.

  2. On chip porous polymer membranes for integration of gastrointestinal tract epithelium with microfluidic 'body-on-a-chip' devices.

    PubMed

    Esch, Mandy Brigitte; Sung, Jong Hwan; Yang, Jennifer; Yu, Changhao; Yu, Jiajie; March, John C; Shuler, Michael Louis

    2012-10-01

    We describe a novel fabrication method that creates microporous, polymeric membranes that are either flat or contain controllable 3-dimensional shapes that, when populated with Caco-2 cells, mimic key aspects of the intestinal epithelium such as intestinal villi and tight junctions. The developed membranes can be integrated with microfluidic, multi-organ cell culture systems, providing access to both sides, apical and basolateral, of the 3D epithelial cell culture. Partial exposure of photoresist (SU-8) spun on silicon substrates creates flat membranes with micrometer-sized pores (0.5-4.0 μm) that--supported by posts--span across 50 μm deep microfluidic chambers that are 8 mm wide and 10 long. To create three-dimensional shapes the membranes were air dried over silicon pillars with aspect ratios of up to 4:1. Space that provides access to the underside of the shaped membranes can be created by isotropically etching the sacrificial silicon pillars with xenon difluoride. Depending on the size of the supporting posts and the pore sizes the overall porosity of the membranes ranged from 4.4 % to 25.3 %. The microfabricated membranes can be used for integrating barrier tissues such as the gastrointestinal tract epithelium, the lung epithelium, or other barrier tissues with multi-organ "body-on-a-chip" devices.

  3. Detecting and Trapping of a Single C. elegans Worm in a Microfluidic Chip for Automated Microplate Dispensing.

    PubMed

    Desta, Israel T; Al-Sharif, Abdelrazak; AlGharibeh, Nour; Mustafa, Nahal; Orozaliev, Ajymurat; Giakoumidis, Nikolaos; Gunsalus, Kristin C; Song, Yong-Ak

    2017-08-01

    Microfluidic devices offer new technical possibilities for a precise manipulation of Caenorhabditis elegans due to the comparable length scale. C. elegans is a small, free-living nematode worm that is a popular model system for genetic, genomic, and high-throughput experimental studies of animal development and neurobiology. In this paper, we demonstrate a microfluidic system in polydimethylsiloxane (PDMS) for dispensing of a single C. elegans worm into a 96-well plate. It consists of two PDMS layers, a flow and a control layer. Using five microfluidic pneumatic valves in the control layer, a single worm is trapped upon optical detection with a pair of optical fibers integrated perpendicular to the constriction channel and then dispensed into a microplate well with a dispensing tip attached to a robotic handling system. Due to its simple design and facile fabrication, we expect that our microfluidic chip can be expanded to a multiplexed dispensation system of C. elegans worms for high-throughput drug screening.

  4. Microfluidic Pneumatic Cages: A Novel Approach for In-chip Crystal Trapping, Manipulation and Controlled Chemical Treatment

    PubMed Central

    Abrishamkar, Afshin; Paradinas, Markos; Bailo, Elena; Rodriguez-Trujillo, Romen; Pfattner, Raphael; Rossi, René M.; Ocal, Carmen; deMello, Andrew J.; Amabilino, David B.; Puigmartí-Luis, Josep

    2016-01-01

    The precise localization and controlled chemical treatment of structures on a surface are significant challenges for common laboratory technologies. Herein, we introduce a microfluidic-based technology, employing a double-layer microfluidic device, which can trap and localize in situ and ex situ synthesized structures on microfluidic channel surfaces. Crucially, we show how such a device can be used to conduct controlled chemical reactions onto on-chip trapped structures and we demonstrate how the synthetic pathway of a crystalline molecular material and its positioning inside a microfluidic channel can be precisely modified with this technology. This approach provides new opportunities for the controlled assembly of structures on surface and for their subsequent treatment. PMID:27500740

  5. From bioseparation to artificial micro-organs: microfluidic chip based particle manipulation techniques

    NASA Astrophysics Data System (ADS)

    Stelzle, Martin

    2010-02-01

    Microfluidic device technology provides unique physical phenomena which are not available in the macroscopic world. These may be exploited towards a diverse array of applications in biotechnology and biomedicine ranging from bioseparation of particulate samples to the assembly of cells into structures that resemble the smallest functional unit of an organ. In this paper a general overview of chip-based particle manipulation and separation is given. In the state of the art electric, magnetic, optical and gravitational field effects are utilized. Also, mechanical obstacles often in combination with force fields and laminar flow are employed to achieve separation of particles or molecules. In addition, three applications based on dielectrophoretic forces for particle manipulation in microfluidic systems are discussed in more detail. Firstly, a virus assay is demonstrated. There, antibody-loaded microbeads are used to bind virus particles from a sample and subsequently are accumulated to form a pico-liter sized aggregate located at a predefined position in the chip thus enabling highly sensitive fluorescence detection. Secondly, subcellular fractionation of mitochondria from cell homogenate yields pure samples as was demonstrated by Western Blot and 2D PAGE analysis. Robust long-term operation with complex cell homogenate samples while avoiding electrode fouling is achieved by a set of dedicated technical means. Finally, a chip intended for the dielectrophoretic assembly of hepatocytes and endothelial cells into a structure resembling a liver sinusoid is presented. Such "artificial micro organs" are envisioned as substance screening test systems providing significantly higher predictability with respect to the in vivo response towards a substance under test.

  6. A Low-Cost Microfluidic Chip for Rapid Genotyping of Malaria-Transmitting Mosquitoes

    PubMed Central

    Liu, Changchun; Mauk, Michael G.; Hart, Robert; Bonizzoni, Mariangela; Yan, Guiyun; Bau, Haim H.

    2012-01-01

    Background Vector control is one of the most effective measures to prevent the transmission of malaria, a disease that causes over 600,000 deaths annually. Around 30–40 Anopheles mosquito species are natural vectors of malaria parasites. Some of these species cannot be morphologically distinguished, but have behavioral and ecological differences. Emblematic of this is the Anopheles gambiae species complex. The correct identification of vector species is fundamental to the development of control strategies and epidemiological studies of disease transmission. Methodology/Principal Findings An inexpensive, disposable, field-deployable, sample-to-answer, microfluidic chip was designed, constructed, and tested for rapid molecular identification of Anopheles gambiae and Anopheles arabiensis. The chip contains three isothermal amplification reactors. One test reactor operates with specific primers to amplify Anopheles gambiae DNA, another with specific primers for Anopheles arabiensis DNA, and the third serves as a negative control. A mosquito leg was crushed on an isolation membrane. Two discs, laden with mosquito tissue, were punched out of the membrane and inserted into the two test chambers. The isolated, disc-bound DNA served as a template in the amplification processes. The amplification products were detected with intercalating fluorescent dye that was excited with a blue light-emitting diode. The emitted light was observed by eye and recorded with a cell-phone camera. When the target consisted of Anopheles gambiae, the reactor containing primers specific to An. gambiae lit up while the other two reactors remained dark. When the target consisted of Anopheles arabiensis, the reactor containing primers specific to An. arabiensis lit up while the other two reactors remained dark. Conclusions/Significance The microfluidic chip provides a means to identify mosquito type through molecular analysis. It is suitable for field work, allowing one to track the geographical

  7. WAT-on-a-chip: a physiologically relevant microfluidic system incorporating white adipose tissue.

    PubMed

    Loskill, Peter; Sezhian, Thiagarajan; Tharp, Kevin M; Lee-Montiel, Felipe T; Jeeawoody, Shaheen; Reese, Willie Mae; Zushin, Peter-James H; Stahl, Andreas; Healy, Kevin E

    2017-05-02

    Organ-on-a-chip systems possess a promising future as drug screening assays and as testbeds for disease modeling in the context of both single-organ systems and multi-organ-chips. Although it comprises approximately one fourth of the body weight of a healthy human, an organ frequently overlooked in this context is white adipose tissue (WAT). WAT-on-a-chip systems are required to create safety profiles of a large number of drugs due to their interactions with adipose tissue and other organs via paracrine signals, fatty acid release, and drug levels through sequestration. We report a WAT-on-a-chip system with a footprint of less than 1 mm(2) consisting of a separate media channel and WAT chamber connected via small micropores. Analogous to the in vivo blood circulation, convective transport is thereby confined to the vasculature-like structures and the tissues protected from shear stresses. Numerical and analytical modeling revealed that the flow rates in the WAT chambers are less than 1/100 of the input flow rate. Using optimized injection parameters, we were able to inject pre-adipocytes, which subsequently formed adipose tissue featuring fully functional lipid metabolism. The physiologically relevant microfluidic environment of the WAT-chip supported long term culture of the functional adipose tissue for more than two weeks. Due to its physiological, highly controlled, and computationally predictable character, the system has the potential to be a powerful tool for the study of adipose tissue associated diseases such as obesity and type 2 diabetes.

  8. Nanophotonic lab-on-a-chip platforms including novel bimodal interferometers, microfluidics and grating couplers.

    PubMed

    Duval, Daphné; González-Guerrero, Ana Belén; Dante, Stefania; Osmond, Johann; Monge, Rosa; Fernández, Luis J; Zinoviev, Kirill E; Domínguez, Carlos; Lechuga, Laura M

    2012-05-08

    One of the main limitations for achieving truly lab-on-a-chip (LOC) devices for point-of-care diagnosis is the incorporation of the "on-chip" detection. Indeed, most of the state-of-the-art LOC devices usually require complex read-out instrumentation, losing the main advantages of portability and simplicity. In this context, we present our last advances towards the achievement of a portable and label-free LOC platform with highly sensitive "on-chip" detection by using nanophotonic biosensors. Bimodal waveguide interferometers fabricated by standard silicon processes have been integrated with sub-micronic grating couplers for efficient light in-coupling, showing a phase resolution of 6.6 × 10(-4)× 2π rad and a limit of detection of 3.3 × 10(-7) refractive index unit (RIU) in bulk. A 3D network of SU-8 polymer microfluidics monolithically assembled at the wafer-level was included, ensuring perfect sealing and compact packaging. To overcome some of the drawbacks inherent to interferometric read-outs, a novel all-optical wavelength modulation system has been implemented, providing a linear response and a direct read-out of the phase variation. Sensitivity, specificity and reproducibility of the wavelength modulated BiMW sensor has been demonstrated through the label-free immunodetection of the human hormone hTSH at picomolar level using a reliable biofunctionalization process.

  9. Biomolecule storage on non-modified thermoplastic microfluidic chip by ink-jet printing of ionogels

    PubMed Central

    Tijero, M.; Díez-Ahedo, R.; Benito-Lopez, F.; Basabe-Desmonts, L.; Castro-López, V.; Valero, A.

    2015-01-01

    This paper reports an innovative technique for reagents storage in microfluidic devices by means of a one-step UV-photoprintable ionogel-based microarray on non-modified polymeric substrates. Although the ionogel and the ink-jet printing technology are well published, this is the first study where both are used for long-term reagent storage in lab-on-a-chip devices. This technology for reagent storage is perfectly compatible with mass production fabrication processes since pre-treatment of the device substrate is not necessary and inkjet printing allows for an efficient reagent deposition process. The functionality of this microarray is demonstrated by testing the release of biotin-647 after being stored for 1 month at room temperature. Analysis of the fluorescence of the ionogel-based microarray that contains biotin-647 demonstrated that 90% of the biotin-647 present was released from the ionogel-based microarray after pumping PBS 0.1% Tween at 37 °C. Moreover, the activity of biotin-647 after being released from the ionogel-based microarray was investigated trough the binding capability of this biotin to a microcontact printed chip surface with avidin. These findings pave the way for a novel, one-step, cheap and mass production on-chip reagents storage method applicable to other reagents such as antibodies and proteins and enzymes. PMID:26339323

  10. On-chip quantitative detection of pathogen genes by autonomous microfluidic PCR platform.

    PubMed

    Tachibana, Hiroaki; Saito, Masato; Shibuya, Shogo; Tsuji, Koji; Miyagawa, Nobuyuki; Yamanaka, Keiichiro; Tamiya, Eiichi

    2015-12-15

    Polymerase chain reaction (PCR)-based genetic testing has become a routine part of clinical diagnoses and food testing. In these fields, rapid, easy-to-use, and cost-efficient PCR chips are expected to be appeared for providing such testing on-site. In this study, a new autonomous disposable plastic microfluidic PCR chip was created, and was utilized for quantitative detection of pathogenic microorganisms. To control the capillary flow of the following solution in the PCR microchannel, a driving microchannel was newly designed behind the PCR microchannel. This allowed the effective PCR by simply dropping the PCR solution onto the inlet without any external pumps. In order to achieve disposability, injection-molded cyclo-olefin polymer (COP) of a cost-competitive plastic was used for the PCR chip. We discovered that coating the microchannel walls with non-ionic surfactant produced a suitable hydrophilic surface for driving the capillary flow through the 1250-mm long microchannel. As a result, quantitative real-time PCR with the lowest initial concentration of human, Escherichia coli (E. coli), and pathogenic E. coli O157 genomic DNA of 4, 0.0019, 0.031 pg/μl, respectively, was successfully achieved in less than 18 min. Our results indicate that the platform presented in this study provided a rapid, easy-to-use, and low-cost real-time PCR system that could be potentially used for on-site gene testing.

  11. Microfluidic polymer chip with an embedded ion-selective electrode detector for nitrate-ion assay in environmental samples.

    PubMed

    Masadome, Takashi; Nakamura, Kazuki; Iijima, Daisuke; Horiuchi, Osamu; Tossanaitada, Benjaporn; Wakida, Shin-ichi; Imato, Toshihiko

    2010-01-01

    A nitrate ion-selective electrode (NO(3)(-)-ISE) has been developed based on tetradodecylammonium bromide as an anion exchanger and 2-nitrophenyl octyl ether as a plasticizer. The NO(3)(-)-ISE shows an almost Nernstian response to nitrate ion over a concentration range between 1.0 x 10(-6) and 1.0 x 10(-1) M, with an anionic slope of -57.7 +/- 0.7 mV/decade. The selectivity coefficients of the NO(3)(-)-ISE for nitrate ion against chloride and sulfate (log k(NO(3)(-)Cl(-))(pot) = -2.42 and log k(NO(3)(-)SO(4)(2-))(pot) = -4.33) were obtained. A microfluidic polymer chip was fabricated using polystyrene plates and stainless-steel wires as a template for the channel. The microfluidic polymer chip is composed of a mixing chip and a NO(3)(-)-ISE detector chip. The microfluidic polymer chip, integrated with a NO(3)(-)-ISE detector consisting of the NO(3)(-)-ISE and a Na(+)-ISE as a reference electrode, showed an almost Nernstian response to nitrate ion over a concentration range between 1.0 x 10(-5) and 1.0 x 10(-1) M, with an anionic slope of -54.3 +/- 1.3 mV/decade. The microfluidic polymer chip was then applied to the determination of nitrate ion in environmental water samples, such as a tap water, a well-water sample and water for agricultural use.

  12. A microfluidic chip for formation and collection of emulsion droplets utilizing active pneumatic micro-choppers and micro-switches.

    PubMed

    Lai, Chia-Wei; Lin, Yen-Heng; Lee, Gwo-Bin

    2008-10-01

    The formation of emulsification droplets is crucial for many industrial applications. This paper reports a new microfluidic chip capable of formation and collection of micro-droplets in liquids for emulsion applications. This microfluidic chip comprising microchannels, a micro-chopper and a micro-switch was fabricated by using micro-electro-mechanical-systems (MEMS) technology. The microfluidic chip can generate uniform droplets with tunable sizes by using combination of flow-focusing and liquid-chopping techniques. The droplet size can be actively fine-tuned by controlling either the relative sheath/sample flow velocity ratios or the chopping frequency. The generated droplets can be then sorted to a specific collection area utilizing an active pneumatic micro-switch formed with three micro-valves. Experimental data showed that the olive oil and sodium-alginate (Na-alginate) droplets with diameters ranging from 3 mum to 70 mum with a variation less than 14% is successfully generated and collected. The development of this microfluidic system can be promising for emulsion, drug delivery and nano-medicine applications.

  13. [Preparation of poly(methyl acrylate) microfluidic chips surface-modified by hyperbranched polyamide ester and their application in the separation of biomolecules].

    PubMed

    Liu, Bing; Lin, Donge; Xu, Lin; Lei, Yanhui; Bo, Qianglong; Shou, Chongqi

    2012-05-01

    The surface of poly (methyl acrylate) (PMMA) microfluidic chips were modified using hyperbranched polyamide ester via chemical bonding. The contact angles of the modified chips were measured. The surface morphology was observed by scanning electron microscope (SEM) and stereo microscope. The results showed that the surface of the modified chips was coated by a dense, uniform, continuous, hydrophilic layer of hyperbranched polyamide ester. The hydrophilic of the chip surface was markedly improved. The contact angle of the chips modified decreased from 89.9 degrees to 29.5 degrees. The electro osmotic flow (EOF) in the modified microchannel was lower than that in the unmodified microchannel. Adenosine and L-lysine were detected and separated via the modified PMMA microfluidic chips. Compared with unmodified chips, the modified chips successfully separated the two biomolecules. The detection peaks were clear and sharp. The separation efficiencies of adenosine and L-lysine were 8.44 x 10(4) plates/m and 9.82 x 10(4) plates/m respectively, and the resolutions (Rs) was 5.31. The column efficiencies and resolutions of the modified chips were much higher than those of the unmodified chips. It was also observed that the modified chips possessed good reproducibility of migration time. This research may provide a new and effective method to improve the hydrophilicity of the PMMA surface and the application of PMMA microfluidic chips in the determination of trace biomolecules.

  14. Single-bead arrays for fluorescence-based immunoassays on capillary-driven microfluidic chips

    NASA Astrophysics Data System (ADS)

    Temiz, Yuksel; Lim, Michel; Delamarche, Emmanuel

    2016-03-01

    We report a concept for the simple fabrication of easy-to-use chips for immunoassays in the context of point-of-care diagnostics. The chip concept comprises mainly three features: (1) the efficient integration of reagents using beads functionalized with receptors, (2) the generation of capillary-driven liquid flows without using external pumps, and (3) a high-sensitivity detection of analytes using fluorescence microscopy. We fabricated prototype chips using dry etching of Si wafers. 4.5-μm-diameter beads were integrated into hexagonal arrays by sedimentation and removing the excess using a stream of water. We studied the effect of different parameters and showed that array occupancies from 30% to 50% can be achieved by pipetting a 250 nL droplet of 1% bead solution and allowing the beads sediment for 3 min. Chips with integrated beads were sealed using a 50-μm-thick dry-film resist laminated at 45 °C. Liquids pipetted to loading pads were autonomously pulled by capillary pumps at a rate of 0.35 nL s-1 for about 30 min. We studied ligand-receptor interactions and binding kinetics using time-lapse fluorescence microscopy and demonstrated a 5 pM limit of detection (LOD) for an anti-biotin immunoassay. As a clinically-relevant example, we implemented an immunoassay to detect prostate specific antigen (PSA) and showed an LOD of 108 fM (i.e. 3.6 pg mL-1). While a specific implementation is provided here for the detection of PSA, we believe that combining capillary-driven microfluidics with arrays of single beads and fluorescence readout to be very flexible and sufficiently sensitive for the detection of other clinically-relevant analytes.

  15. A microfluidic chip for generating reactive plasma at gas-gas interface formed in laminar flow

    NASA Astrophysics Data System (ADS)

    Hashimoto, Masahiro; Tsukasaki, Katsuki; Kumagai, Shinya; Sasaki, Minoru

    2015-01-01

    A gas-gas interface is used for generating a localized reactive plasma flow at an atmospheric pressure. A microfluidic chip is fabricated as the reactor integrating a small plasma source located upstream. Within a Y-shaped microchannel, a discharging gas flows with a chemical gas. Owing to the small width of the microchannel, the gas flow is stabilized in a laminar flow. The resultant gas-gas interface is formed in the area where two gases flow facing each other activating the chemical gas through the energetic species in the discharging gas. A characteristic stream pattern is observed as the etching profile of a carbon film with a sub-µm sharp step change that can be explained by the spatial distribution of the reactive oxygen. This etching profile is different from that obtained when plasma discharging occurs near the channel exit being affected by the turbulent flow.

  16. A competitive luminol chemiluminescence immunosensor based on a microfluidic chip for the determination of ractopamine.

    PubMed

    Wang, Sai; Chen, Qilong; Wei, Xiao; Wu, Jian; Wang, Chunyan; Liu, Jiahui; Zhang, Liya; Dong, Yiyang

    2017-01-01

    Herein, a competitive luminol chemiluminescence immunosensor based on a microfluidic chip was developed to detect ractopamine (RCT) both in phosphate buffer and swine urine samples. The immunosensor can provide a liner range of 0.5-40 ng/mL and a high sensitivity with a limit of detection of 0.97 ng/mL for RCT detection in swine urine. Good rates of recovery in negative swine urine samples were achieved over the RCT concentration ranging from 0.5 to 40 ng/mL. The proposed method offered a promising analytical scheme for the on-site determination of RCT. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. On-chip multi-gas incubation for microfluidic cell cultures under hypoxia

    PubMed Central

    Tanaka, Masato

    2014-01-01

    We developed a simple system that regulates CO2 and O2 levels within a microfluidic chip. This system enables long-term cell culture under hypoxic conditions without the need of a CO2 incubator or a multi-gas incubator. Hypoxic conditions were generated using a miniature water jacket containing dissolved ascorbate as an oxygen scavenger. Formulations of the water jacket were determined that enables both 5% pCO2 and desired pO2 levels ranging from 5 to 15%. We also cultured PC-12 cells and primary neuronal cells from chick embryos under hypoxia and observed hypoxia-induced cell death and inhibition of neurite outgrowth. PMID:25553177

  18. Dynamic monitoring of membrane nanotubes formation induced by vaccinia virus on a high throughput microfluidic chip

    PubMed Central

    Xiao, Min; Xu, Na; Wang, Cheng; Pang, Dai-Wen; Zhang, Zhi-Ling

    2017-01-01

    Membrane nanotubes (MNTs) are physical connections for intercellular communication and induced by various viruses. However, the formation of vaccinia virus (VACV)-induced MNTs has never been studied. In this report, VACV-induced MNTs formation process was monitored on a microfluidic chip equipped with a series of side chambers, which protected MNTs from fluidic shear stress. MNTs were formed between susceptible cells and be facilitated by VACV infection through three patterns. The formed MNTs varied with cell migration and virus concentration. The length of MNTs was positively correlated with the distance of cell migration. With increasing virus titer, the peak value of the ratio of MNT-carried cell appeared earlier. The immunofluorescence assay indicated that the rearrangement of actin fibers induced by VACV infection may lead to the formation of MNTs. This study presents evidence for the formation of MNTs induced by virus and helps us to understand the relationship between pathogens and MNTs. PMID:28317863

  19. Microfluidic chips with multi-junctions: an advanced tool in recovering proteins from inclusion bodies

    PubMed Central

    Yamaguchi, Hiroshi; Miyazaki, Masaya

    2015-01-01

    Active recombinant proteins are used for studying the biological functions of genes and for the development of therapeutic drugs. Overexpression of recombinant proteins in bacteria often results in the formation of inclusion bodies, which are protein aggregates with non-native conformations. Protein refolding is an important process for obtaining active recombinant proteins from inclusion bodies. However, the conventional refolding method of dialysis or dilution is time-consuming and recovered active protein yields are often low, and a cumbersome trial-and-error process is required to achieve success. To circumvent these difficulties, we used controllable diffusion through laminar flow in microchannels to regulate the denaturant concentration. This method largely aims at reducing protein aggregation during the refolding procedure. This Commentary introduces the principles of the protein refolding method using microfluidic chips and the advantage of our results as a tool for rapid and efficient recovery of active recombinant proteins from inclusion bodies. PMID:25531187

  20. Microfluidic chips with multi-junctions: an advanced tool in recovering proteins from inclusion bodies.

    PubMed

    Yamaguchi, Hiroshi; Miyazaki, Masaya

    2015-01-01

    Active recombinant proteins are used for studying the biological functions of genes and for the development of therapeutic drugs. Overexpression of recombinant proteins in bacteria often results in the formation of inclusion bodies, which are protein aggregates with non-native conformations. Protein refolding is an important process for obtaining active recombinant proteins from inclusion bodies. However, the conventional refolding method of dialysis or dilution is time-consuming and recovered active protein yields are often low, and a cumbersome trial-and-error process is required to achieve success. To circumvent these difficulties, we used controllable diffusion through laminar flow in microchannels to regulate the denaturant concentration. This method largely aims at reducing protein aggregation during the refolding procedure. This Commentary introduces the principles of the protein refolding method using microfluidic chips and the advantage of our results as a tool for rapid and efficient recovery of active recombinant proteins from inclusion bodies.

  1. Dynamic monitoring of membrane nanotubes formation induced by vaccinia virus on a high throughput microfluidic chip

    NASA Astrophysics Data System (ADS)

    Xiao, Min; Xu, Na; Wang, Cheng; Pang, Dai-Wen; Zhang, Zhi-Ling

    2017-03-01

    Membrane nanotubes (MNTs) are physical connections for intercellular communication and induced by various viruses. However, the formation of vaccinia virus (VACV)-induced MNTs has never been studied. In this report, VACV-induced MNTs formation process was monitored on a microfluidic chip equipped with a series of side chambers, which protected MNTs from fluidic shear stress. MNTs were formed between susceptible cells and be facilitated by VACV infection through three patterns. The formed MNTs varied with cell migration and virus concentration. The length of MNTs was positively correlated with the distance of cell migration. With increasing virus titer, the peak value of the ratio of MNT-carried cell appeared earlier. The immunofluorescence assay indicated that the rearrangement of actin fibers induced by VACV infection may lead to the formation of MNTs. This study presents evidence for the formation of MNTs induced by virus and helps us to understand the relationship between pathogens and MNTs.

  2. An integrated microfluidic chip for immunocapture, preconcentration and separation of β-amyloid peptides

    PubMed Central

    Mohamadi, Reza M.; Svobodova, Zuzana; Bilkova, Zuzana; Otto, Markus; Taverna, Myriam; Descroix, Stephanie; Viovy, Jean-Louis

    2015-01-01

    We present an integrated microfluidic chip for detection of β-amyloid (Aβ) peptides. Aβ peptides are major biomarkers for the diagnosis of Alzheimer's disease (AD) in its early stages. This microfluidic device consists of three main parts: (1) An immunocapture microcolumn based on self-assembled magnetic beads coated with antibodies specific to Aβ peptides, (2) a nano-porous membrane made of photopolymerized hydrogel for preconcentration, and (3) a microchip electrophoresis (MCE) channel with fluorescent detection. Sub-milliliter sample volume is either mixed off-chip with antibody coated magnetic beads and injected into the device or is injected into an already self-assembled column of magnetic beads in the microchannel. The captured peptides on the beads are then electrokinetically eluted and re-concentrated onto the nano-membrane in a few nano-liters. By integrating the nano-membrane, total assay time was reduced and also off-chip re-concentration or buffer exchange steps were not needed. Finally, the concentrated peptides in the chip are separated by electrophoresis in a polymer-based matrix. The device was applied to the capture and MCE analysis of differently truncated peptides Aβ (1–37, 1–39, 1–40, and 1–42) and was able to detect as low as 25 ng of synthetic Aβ peptides spiked in undiluted cerebrospinal fluid (CSF). The device was also tested with CSF samples from healthy donors. CSF samples were fluorescently labelled and pre-mixed with the magnetic beads and injected into the device. The results indicated that Aβ1-40, an important biomarker for distinguishing patients with frontotemporal lobe dementia from controls and AD patients, was detectable. Although the sensitivity of this device is not yet enough to detect all Aβ subtypes in CSF, this is the first report on an integrated or semi-integrated device for capturing and analyzing of differently truncated Aβ peptides. The method is less demanding and faster than the conventional

  3. An RNA-DNA hybridization assay chip with electrokinetically controlled oil droplet valves for sequential microfluidic operations.

    PubMed

    Weng, Xuan; Jiang, Hai; Chon, Chan Hee; Chen, Shu; Cao, Honghe; Li, Dongqing

    2011-09-20

    A novel RNA-DNA hybridization microfluidic chip for detecting pathogens was developed. The on-chip sequential operations of reagent delivery and washing processes in the hybridization assay were performed by gravity-based pressure-driven flow controlled by a pair of electrokinetically controlled oil-droplet sequence valves (ECODSVs). Numerical method was used to simulate the fluidic processes of reagents in the complex microchannel network. Based on the parameters determined from the numerical simulations, a reasonable hybridization assay microfluidic chip was developed. The application of this on-chip assay to detect Salmonella was demonstrated. Significantly shortened assay time (25 min) and a 3-20-fold reduction in reagent/sample consumption were achieved. The detection limit was 10³ CFU/mL which is comparable to the conventional assay. With further development of automatic control and the improvement of the detection strategy, this microfluidic RNA-DNA hybridization assay technique has a potential for point-of-testing applications. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Combination of antibody-coated, physical-based microfluidic chip with wave-shaped arrays for isolating circulating tumor cells.

    PubMed

    Chen, Hongmei; Cao, Baoshan; Chen, Hongda; Lin, Yu-Sheng; Zhang, Jingjing

    2017-09-01

    Circulating tumor cells (CTCs) are found in the peripheral blood of patients with metastatic cancers, which have critical significance in cancer prognosis and diagnostics. Enumeration is significantly valuable since number of CTCs is strongly correlated to severity of disease. This article is proposed and demonstrated an antibody-coated, size-based microfluidic chip with wave-shaped arrays could efficiently capture CTCs combining two separation methods of both size- and deformability-based and affinity-based segregation. Utilizing immunocapture of capture chemistry of Epithelial Cell Adhension Molecule (EpCAM), tumor cells could be captured by narrow gaps or have a friction with microposts edges to realize both immune-affinity and size capture. This wave-shaped layout of microfluidic chip with varying gaps between adjacent circular microposts can generate perpendicular velocities to the fluidic direction. This oriented fluidic direction will carry cells to next smaller neighboring gap and then be captured gradually. The experiment results indicate capture efficiency is ~90% and viability is ~95% after extracted and cultured 3 days. Furthermore, this chip has been validated for whole blood with cancer cell lines and mimic patient blood. This study demonstrates feasibility using our microfluidic chip for CTCs research, monitoring cancer progress and evaluating therapeutic treatment.

  5. Smart portable electrophoresis instrument based on multipurpose microfluidic chips with electrochemical detection.

    PubMed

    Fernández-la-Villa, Ana; Sánchez-Barragán, Dámaso; Pozo-Ayuso, Diego F; Castaño-Álvarez, Mario

    2012-09-01

    A second generation of a battery-powered portable electrophoresis instrument for the use of ME with electrochemical detection was developed. As the first-generation, the main unit of the instrument (150 mm × 165 mm × 95 mm) consists of four-outputs high-voltage power supply (HVPS) with maximum voltage of 3 KV and acquisition system (bipotentiostat) containing 2-channels for dual electrochemical detection. A new reusable microfluidic platform was designed in order to incorporate the microchips with the portable instrument. In this case, the platform is integrated to the main unit of the instrument so that it is not necessary to have any external cable for the interconnection of both parts, making the use of the complete system easier. The new platform contains all the electrical connections for the HVPS and bipotentiostat, as well as fluidic ports for driving the solutions. The microfluidic electrophoresis instrument is controlled by means of a user-friendly interface from a computer. The possibility of wireless connection (Bluetooth®) allows the use of the instrument without any external cable improving the portability. Therefore, the second generation brings a more compact and integrated electrophoresis instrument for "in situ" applications using microfluidic chips in an easy way. The performance of the electrophoresis system was initially evaluated using single- and dual-channel SU-8/Pyrex microchips with different models of integrated electrodes including microelectrodes and interdigitated arrays. The method was tested in different analytical applications such as separation of neurotransmitters, chlorophenols, purine derivatives, vitamins, polyphenolic acids, and flavones.

  6. Isolation and amplification of mRNA within a simple microfluidic lab on a chip.

    PubMed

    Reinholt, Sarah J; Behrent, Arne; Greene, Cassandra; Kalfe, Ayten; Baeumner, Antje J

    2014-01-07

    The major modules for realizing molecular biological assays in a micro-total analysis system (μTAS) were developed for the detection of pathogenic organisms. The specific focus was the isolation and amplification of eukaryotic mRNA within a simple, single-channel device for very low RNA concentrations that could then be integrated with detection modules. The hsp70 mRNA from Cryptosporidium parvum was used as a model analyte. Important points of study were surface chemistries within poly(methyl methacrylate) (PMMA) microfluidic channels that enabled specific and sensitive mRNA isolation and amplification reactions for very low mRNA concentrations. Optimal conditions were achieved when the channel surface was carboxylated via UV/ozone treatment followed by the immobilization of polyamidoamine (PAMAM) dendrimers on the surface, thus increasing the immobilization efficiency of the thymidine oligonucleotide, oligo(dT)25, and providing a reliable surface for the amplification reaction, importantly, without the need for blocking agents. Additional chemical modifications of the remaining active surface groups were studied to avoid nonspecific capturing of nucleic acids and hindering of the mRNA amplification at low RNA concentrations. Amplification of the mRNA was accomplished using nucleic acid sequence-based amplification (NASBA), an isothermal, primer-dependent technique. Positive controls consisting of previously generated NASBA amplicons could be diluted 10(15) fold and still result in successful on-chip reamplification. Finally, the successful isolation and amplification of mRNA from as few as 30 C. parvum oocysts was demonstrated directly on-chip and compared to benchtop devices. This is the first proof of successful mRNA isolation and NASBA-based amplification of mRNA within a simple microfluidic device in relevant analytical volumes.

  7. Recombinant spider silk from aqueous solutions via a bio-inspired microfluidic chip

    NASA Astrophysics Data System (ADS)

    Peng, Qingfa; Zhang, Yaopeng; Lu, Li; Shao, Huili; Qin, Kankan; Hu, Xuechao; Xia, Xiaoxia

    2016-11-01

    Spiders achieve superior silk fibres by controlling the molecular assembly of silk proteins and the hierarchical structure of fibres. However, current wet-spinning process for recombinant spidroins oversimplifies the natural spinning process. Here, water-soluble recombinant spider dragline silk protein (with a low molecular weight of 47 kDa) was adopted to prepare aqueous spinning dope. Artificial spider silks were spun via microfluidic wet-spinning, using a continuous post-spin drawing process (WS-PSD). By mimicking the natural spinning apparatus, shearing and elongational sections were integrated in the microfluidic spinning chip to induce assembly, orientation of spidroins, and fibril structure formation. The additional post-spin drawing process following the wet-spinning section partially mimics the spinning process of natural spider silk and substantially contributes to the compact aggregation of microfibrils. Subsequent post-stretching further improves the hierarchical structure of the fibres, including the crystalline structure, orientation, and fibril melting. The tensile strength and elongation of post-treated fibres reached up to 510 MPa and 15%, respectively.

  8. Combined Dielectrophoresis and Impedance Systems for Bacteria Analysis in Microfluidic On-Chip Platforms

    PubMed Central

    Páez-Avilés, Cristina; Juanola-Feliu, Esteve; Punter-Villagrasa, Jaime; del Moral Zamora, Beatriz; Homs-Corbera, Antoni; Colomer-Farrarons, Jordi; Miribel-Català, Pere Lluís; Samitier, Josep

    2016-01-01

    Bacteria concentration and detection is time-consuming in regular microbiology procedures aimed to facilitate the detection and analysis of these cells at very low concentrations. Traditional methods are effective but often require several days to complete. This scenario results in low bioanalytical and diagnostic methodologies with associated increased costs and complexity. In recent years, the exploitation of the intrinsic electrical properties of cells has emerged as an appealing alternative approach for concentrating and detecting bacteria. The combination of dielectrophoresis (DEP) and impedance analysis (IA) in microfluidic on-chip platforms could be key to develop rapid, accurate, portable, simple-to-use and cost-effective microfluidic devices with a promising impact in medicine, public health, agricultural, food control and environmental areas. The present document reviews recent DEP and IA combined approaches and the latest relevant improvements focusing on bacteria concentration and detection, including selectivity, sensitivity, detection time, and conductivity variation enhancements. Furthermore, this review analyses future trends and challenges which need to be addressed in order to successfully commercialize these platforms resulting in an adequate social return of public-funded investments. PMID:27649201

  9. Single Cell Mass Measurement Using Drag Force Inside Lab-on-Chip Microfluidics System.

    PubMed

    Rahman, Md Habibur; Ahmad, Mohd Ridzuan; Takeuchi, Masaru; Nakajima, Masahiro; Hasegawa, Yasuhisa; Fukuda, Toshio

    2015-12-01

    Single cell mass (SCM) is an intrinsic property of single cell, it arouses a great interest among scientists as cell mass depends on the synthesis of proteins, DNA replication, cell wall stiffness, cell cytoplasm density, cell growth, ribosome, and other analogous of organisms. To date, several great strides have been taken to the advancements of SCM measurement techniques. Nevertheless, more works are required to enable the technology to push frontier in deep analysis of SCM measurement, hence to elucidate intracellular properties. In this paper, we present a lab-on-chip microfluidics system for SCM measurement, related with the force required to drag a single cell and Newton's law of motion inside microfluidics channel. Drag force on the cell was generated by a pressure driven syringe micropump and the motion of the cell was measured using optical observation under an inverted microscope. This approach of measuring SCM was calibrated using known mass (77.3 pg) of a polystyrene particle of 5.2 μm diameter. Furthermore, we used Saccharomyces cerevisiae baker's yeast cells of different sizes ([Formula: see text] diameter) for SCM measurement. Mass of 4.4 μm diameter of single yeast cell was measured as 2.12 pg which is in the range of previously reported single yeast cell mass (2-3 pg). In addition, we also studied the relation between SCM and single cell size. Results showed that single yeast cell mass increases exponentially with the increasing of single cell size.

  10. Single Cell Mass Measurement Using Drag ForceInside Lab-on-Chip Microfluidics System.

    PubMed

    Rahman, Md; Ahmad, Mohd; Takeuchi, Masaru; Nakajima, Masahiro; Hasegawa, Yasuhisa; Fukuda, Toshio

    2015-12-22

    Single Cell Mass (SCM) is an intrinsic property of single cell, it arouses a great interest among scientists as cell mass depends on the synthesis of proteins, DNA replication, cell wall stiffness, cell cytoplasm density, cell growth, ribosome and other analogous of organisms. To date, several great strides have been taken to the advancements of SCM measurement techniques. Nevertheless, more works are required to enable the technology to push frontier in deep analysis of SCM measurement, hence to elucidate intracellular properties. In this paper, we present a Lab-on-Chip microfluidics system for SCM measurement, related with the force required to drag a single cell and Newton's law of motion inside microfluidics channel. Drag force on the cell was generated by a pressure driven syringe micropump and the motion of the cell was measured using optical observation under an inverted microscope. This approach of measuring SCM was calibrated using known mass (77.3 pg) of a polystyrene particle of 5.2 μm diameter. Furthermore, we used Saccharomyces cerevisiae baker's yeast cells of different sizes (2-7 μm diameter) for SCM measurement. Mass of 4.4 μm diameter of single yeast cell was measured as 2.12 pg which is in the range of previously reported single yeast cell mass (2-3 pg). In addition, we also studied the relation between SCM and single cell size. Results showed that single yeast cell mass increases exponentially with the increasing of single cell size.

  11. Generation of Monodisperse Liquid Droplets in a Microfluidic Chip Using a High-Speed Gaseous Microflow

    NASA Astrophysics Data System (ADS)

    Tirandazi, Pooyan; Hidrovo, Carlos

    2015-11-01

    Over the last few years, microfluidic systems known as Lab-on-a-Chip (LOC) and micro total analysis systems (μTAS) have been increasingly developed as essential components for numerous biochemical applications. Droplet microfluidics, however, provides a distinctive attribute for delivering and processing discrete as well as ultrasmall volumes of fluid, which make droplet-based systems more beneficial over their continuous-phase counterparts. Droplet generation in its conventional scheme usually incorporates the injection of a liquid (water) into a continuous immiscible liquid (oil) medium. In this study we demonstrate a novel scheme for controlled generation of monodisperse droplets in confined gas-liquid microflows. We experimentally investigate the manipulation of water droplets in flow-focusing configurations using a high inertial air stream. Different flow regimes are observed by varying the gas and liquid flow rates, among which, the ``dripping regime'' where monodisperse droplets are generated is of great importance. The controlled size and generation rate of droplets in this region provide the capability for precise and contaminant-free delivery of microliter to nanoliter volumes of fluid. Furthermore, the high speed droplets generated in this method represent the basis for a new approach based on droplet pair collisions for fast efficient micromixing which provides a significant development in modern LOC and μTAS devices. This project is currently being supported by an NSF CAREER Award grant CBET-1151091.

  12. Measurement of platelet aggregation functions using whole blood migration ratio in a microfluidic chip.

    PubMed

    Seo, Hong Seog; Choi, Sung Hyuk; Han, Miran; Kim, Kyeong Ah; Cho, Chi Hyun; An, Seong Soo A; Lim, Chae Seung; Shin, Sehyun

    2016-01-01

    Platelets play a major role in maintaining endothelial integrity and hemostasis. Of the various soluble agonists, ADP is an important in vivo stimulus for inducing platelet aggregation. In this study, a simple, rapid, and affordable method was designed for testing bleeding time (BT) and platelet aggregation with a two-channel microfluidic chip. Whole blood migration ratio (MR) from a microchip system was evaluated in comparison to the closure time (CT) from PFA-100 assays (Siemens, Germany) and CD62P expression on platelets. To induce platelet aggregation, a combination of collagen (1.84 mg/ml) and ADP (37.5 mg/ml) were used as agonists. After adding the agonists to samples, whole blood MR from the microchip system was measured. The outcome of the assessment depended on reaction time and agonist concentration. MR of whole blood from the microchip system was significantly correlated with CT from PFA-100 (r = 0.61, p <  0.05, n = 60). In addition, MR was negatively correlated with CD62P expression (r =-0.95, p <  0.05, n = 60). These results suggest that the measurement of MR using agonists is an easy, simple and efficient method for monitoring platelet aggregation in normal and ADP-receptors defective samples, along with the BT test. Thus, usage of the current microfluidic method could expand to diverse applications, including efficacy assessments in platelet therapy.

  13. Recombinant spider silk from aqueous solutions via a bio-inspired microfluidic chip

    PubMed Central

    Peng, Qingfa; Zhang, Yaopeng; Lu, Li; Shao, Huili; Qin, Kankan; Hu, Xuechao; Xia, Xiaoxia

    2016-01-01

    Spiders achieve superior silk fibres by controlling the molecular assembly of silk proteins and the hierarchical structure of fibres. However, current wet-spinning process for recombinant spidroins oversimplifies the natural spinning process. Here, water-soluble recombinant spider dragline silk protein (with a low molecular weight of 47 kDa) was adopted to prepare aqueous spinning dope. Artificial spider silks were spun via microfluidic wet-spinning, using a continuous post-spin drawing process (WS-PSD). By mimicking the natural spinning apparatus, shearing and elongational sections were integrated in the microfluidic spinning chip to induce assembly, orientation of spidroins, and fibril structure formation. The additional post-spin drawing process following the wet-spinning section partially mimics the spinning process of natural spider silk and substantially contributes to the compact aggregation of microfibrils. Subsequent post-stretching further improves the hierarchical structure of the fibres, including the crystalline structure, orientation, and fibril melting. The tensile strength and elongation of post-treated fibres reached up to 510 MPa and 15%, respectively. PMID:27819339

  14. On chip droplet characterization: a practical, high-sensitivity measurement of droplet impedance in digital microfluidics.

    PubMed

    Sadeghi, Saman; Ding, Huijiang; Shah, Gaurav J; Chen, Supin; Keng, Pei Yuin; Kim, Chang-Jin; van Dam, R Michael

    2012-02-21

    We demonstrate a new approach to impedance measurement on digital microfluidics chips for the purpose of simple, sensitive, and accurate volume and liquid composition measurement. Adding only a single series resistor to existing AC droplet actuation circuits, the platform is simple to implement and has negligible effect on actuation voltage. To accurately measure the complex voltage across the resistor (and hence current through the device and droplet), the designed system is based on software-implemented lock-in amplification detection of the voltage drop across the resistor which filters out noise, enabling high-resolution and low-limit signal recovery. We observe picoliter sensitivity with linear correlation of voltage to volume extending to the microliter volumes that can be handled by digital microfluidic devices. Due to the minimal hardware, the system is robust and measurements are highly repeatable. The detection technique provides both phase and magnitude information of the real-time current flowing through the droplet for a full impedance measurement. The sensitivity and resolution of this platform enables it to distinguish between various liquids which, as demonstrated in this paper, could potentially be extended to quantify solute concentrations, liquid mixtures, and presence of analytes.

  15. A hybrid microfluidic chip with electrowetting functionality using ultraviolet (UV)-curable polymer.

    PubMed

    Gu, Hao; Duits, Michel H G; Mugele, Frieder

    2010-06-21

    Electrowetting (EW) is widely used in digital microfluidics for the manipulation of drops sandwiched between two parallel plates. In contrast, demonstrations of closed microfluidic channels enhanced with EW functionality are scarce. Here, we report a simple, low-cost method to construct such microchannels enclosed between two glass plates, each of which comprises electrodes and insulating layers. Our method uses soft imprint lithography with thiolene precursors to design the channel geometry. UV exposure is used to seal the chips permanently and a silanization treatment renders all inner channel surfaces hydrophobic. Compared to earlier polydimethylsiloxane-based designs, this method allows us to make microchannels with smaller dimensions (down to 10 microns), lower aspect ratios (down to height/length=1/10), and symmetric electrodes both on the top and the bottom of the channel. We demonstrate the new capabilities with two examples: (i) EW-enhanced drop generation in a flow focusing geometry allows precise and continuous control on drop diameter in the range approximately 1-15 microns while maintaining monodispersity; (ii) EW allows tuning of the excess water pressure needed to displace oil in a microchannel, leading to spontaneous imbibition at EW number eta>0.89.

  16. Microfluidic chip with optical sensor for rapid detection of nerve agent Sarin in water samples

    NASA Astrophysics Data System (ADS)

    Tan, Hsih Yin; Nguyen, Nam-Trung; Loke, Weng Keong; Tan, Yong Teng

    2007-12-01

    The chemical warfare agent Sarin is an organophosphate that is highly toxic to humans as they can act as cholinesterase inhibitors, that disrupts neuromuscular transmission. As these nerve agents are colorless, odorless and highly toxic, they can be introduced into drinking water as a means of terrorist sabotage. Hence, numerous innovative devices and methods have been developed for rapid detection of these organophosphates. Microfluidic technology allows the implementation of fast and sensitive detection of Sarin. In this paper, a micro-total analysis systems (TAS), also known as Lab-on-a-chip, fitted with an optical detection system has been developed to analyze the presence of the nerve agent sarin in water samples. In the present set-up, inhibition of co-introduced cholinesterase and water samples containing trace amounts of nerve agent sarin into the microfluidic device was used as the basis for selective detection of sarin. The device was fabricated using polymeric micromachining with PMMA (poly (methymethacrylate)) as the substrate material. A chromophore was utilized to measure the activity of remnant cholinesterase activity, which is inversely related to the amount of sarin present in the water samples. Comparisons were made between two different optical detection techniques and the findings will be presented in this paper. The presented measurement method is simple, fast and as sensitive as Gas Chromatography.

  17. High-throughput sorting of drops in microfluidic chips using electric capacitance

    PubMed Central

    Pit, Arjen M.; de Ruiter, Riëlle; Kumar, Anand; Wijnperlé, Daniel; Duits, Michèl H. G.; Mugele, Frieder

    2015-01-01

    We analyze a recently introduced approach for the sorting of aqueous drops with biological content immersed in oil, using a microfluidic chip that combines the functionality of electrowetting with the high throughput of two-phase flow microfluidics. In this electrostatic sorter, three co-planar electrodes covered by a thin dielectric layer are placed directly below the fluidic channel. Switching the potential of the central electrode creates an electrical guide that leads the drop to the desired outlet. The generated force, which deflects the drop, can be tuned via the voltage. The working principle is based on a contrast in conductivity between the drop and the continuous phase, which ensures successful operation even for drops of highly conductive biological media like phosphate buffered saline. Moreover, since the electric field does not penetrate the drop, its content is protected from electrical currents and Joule heating. A simple capacitive model allows quantitative prediction of the electrostatic forces exerted on drops. The maximum achievable sorting rate is determined by a competition between electrostatic and hydrodynamic forces. Sorting speeds up to 1200 per second are demonstrated for conductive drops of 160 pl in low viscosity oil. PMID:26339316

  18. Assessment of mitochondrial membrane potential using an on-chip microelectrode in a microfluidic device.

    PubMed

    Lim, Tae-Sun; Dávila, Antonio; Wallace, Douglas C; Burke, Peter

    2010-07-07

    The mitochondrial membrane potential is used to generate and regulate energy in living systems, driving the conversion of ADP to ATP, regulating ion homeostasis, and controlling apoptosis, all central to human health and disease. Therefore, there is a need for tools to study its regulation in a controlled environment for potential clinical and scientific applications. For this aim, an on-chip tetraphenylphosphonium (TPP(+)) selective microelectrode sensor was constructed in a microfluidic environment. The concentration of isolated mitochondria (Heb7A) used in a membrane potential measurement was 0.3 ng microL(-1), four orders of magnitude smaller than the concentration used in conventional assays (3 microg microL(-1)). In addition, the volume of the chamber (85 microL) is 2 orders of magnitude smaller than traditional experiments. As a demonstration, changes in the membrane potential are clearly measured in response to a barrage of well-known substrates and inhibitors of the electron transport chain. This general approach, which to date has not been demonstrated for study of mitochondrial function and bio-energetics in generally, can be instrumental in advancing the field of mitochondrial research and clinical applications by allowing high throughput studies of the regulation, dynamics, and statistical properties of the mitochondrial membrane potential in response to inhibitors and inducers of apoptosis in a controlled (microfluidic) chemical environment.

  19. Microfluidic devices for cell culture and handling in organ-on-a-chip applications

    NASA Astrophysics Data System (ADS)

    Becker, Holger; Schulz, Ingo; Mosig, Alexander; Jahn, Tobias; Gärtner, Claudia

    2014-03-01

    For many problems in system biology or pharmacology, in-vivo-like models of cell-cell interactions or organ functions are highly sought after. Conventional stationary cell culture in 2D plates quickly reaches its limitations with respect to an in-vivo like expression and function of individual cell types. Microfabrication technologies and microfluidics offer an attractive solution to these problems. The ability to generate flow as well as geometrical conditions for cell culture and manipulation close to the in-vivo situation allows for an improved design of experiments and the modeling of organ-like functionalities. Furthermore, reduced internal volumes lead to a reduction in reagent volumes necessary as well as an increased assay sensitivity. In this paper we present a range of microfluidic devices designed for the co-culturing of a variety of cells. The influence of substrate materials and surface chemistry on the cell morphology and viability for long-term cell culture has been investigated as well as strategies and medium supply for on-chip cell cultivation.

  20. Glucose microfluidic fuel cell based on silver bimetallic selective catalysts for on-chip applications

    NASA Astrophysics Data System (ADS)

    Cuevas-Muñiz, F. M.; Guerra-Balcázar, M.; Esquivel, J. P.; Sabaté, N.; Arriaga, L. G.; Ledesma-García, J.

    2012-10-01

    A glucose microfluidic fuel cell with outstanding performance at zero flow condition is presented. Polarization tests showed that bimetallic materials based in silver (AuAg/C as anode, PtAg/C as cathode) exhibit tolerance to byproducts and crossover effect. This allowed achieving one of the highest power densities reported for glucose fuel cells, up to a value of 630 μW cm-2 using two separated laminar flows of reactants. Furthermore, the tolerance to crossover effect caused by the selectivity of PtAg/C to oxygen reduction reaction in presence of glucose permitted using a single flow containing a mixture of glucose/oxygen, yielding a performance as high as 270 μW cm-2. Microfluidic fuel cell was further evaluated with a simulated body fluid solution that contained salts commonly present in the human blood plasma, reaching a power of 240 μW cm-2 at zero flow. These results envisage the incorporation of this fuel cell as a portable power source in Lab-on-a-Chip devices without the need of external pumps.

  1. A simple method for fabricating multi-layer PDMS structures for 3D microfluidic chips.

    PubMed

    Zhang, Mengying; Wu, Jinbo; Wang, Limu; Xiao, Kang; Wen, Weijia

    2010-05-07

    We report a simple methodology to fabricate PDMS multi-layer microfluidic chips. A PDMS slab was surface-treated by trichloro (1H,1H,2H,2H-perfluorooctyl) silane, and acts as a reusable transferring layer. Uniformity of the thickness of the patterned PDMS layer and the well-alignment could be achieved due to the transparency and proper flexibility of this transferring layer. Surface treatment results are confirmed by XPS and contact angle testing, while bonding forces between different layers were measured for better understanding of the transferring process. We have also designed and fabricated a few simple types of 3D PDMS chip, especially one consisting of 6 thin layers (each with thickness of 50 mum), to demonstrate the potential utilization of this technique. 3D fluorescence images were taken by a confocal microscope to illustrate the spatial characters of essential parts. This fabrication method is confirmed to be fast, simple, repeatable, low cost and possible to be mechanized for mass production.

  2. Continuous enrichment of circulating tumor cells using a microfluidic lateral flow filtration chip.

    PubMed

    Lee, Sung-Woo; Hyun, Kyung-A; Kim, Seung-Il; Kang, Ji-Yoon; Jung, Hyo-Il

    2015-01-16

    The isolation and characterization of circulating tumor cells (CTC) is of great importance in cancer diagnosis and prognosis. Highly sensitive detection of CTCs can be very difficult because they are extremely rare (i.e., 1-5 CTCs per 10(9) erythrocytes) in blood. Recently, various devices have been developed that exploit biochemical (affinity-based) and physical (size or density) methods. Antibody-based isolation has its own limitations, as the expression level of the epitopes for an antibody varies due to the heterogeneity of cancer cells. Harsh conditions associated with physical methods can cause the deformation and damage of CTCs during the isolation process. Here, we propose a microfluidic lateral flow filtration (μ-LaFF) chip in which lateral flow was combined with vertical flow into the filter to capture the CTCs gently. The CTCs experienced weak shear flow owing to the lateral flow and traveled alongside the filter channel until finally being captured. The vertical flow in the filter held the captured cells tightly and served as an exit for uncaptured hematological cells (white and red blood cells). From our μ-LaFF chip we obtained a high capture efficiency (95%) and purity (99%), minimizing any damage to the CTCs. Our μ-LaFF technology is expected to be useful in the diagnosis and prognosis of various cancers.

  3. Rapid and Low-Cost CRP Measurement by Integrating a Paper-Based Microfluidic Immunoassay with Smartphone (CRP-Chip).

    PubMed

    Dong, Meili; Wu, Jiandong; Ma, Zimin; Peretz-Soroka, Hagit; Zhang, Michael; Komenda, Paul; Tangri, Navdeep; Liu, Yong; Rigatto, Claudio; Lin, Francis

    2017-03-26

    Traditional diagnostic tests for chronic diseases are expensive and require a specialized laboratory, therefore limiting their use for point-of-care (PoC) testing. To address this gap, we developed a method for rapid and low-cost C-reactive protein (CRP) detection from blood by integrating a paper-based microfluidic immunoassay with a smartphone (CRP-Chip). We chose CRP for this initial development because it is a strong biomarker of prognosis in chronic heart and kidney disease. The microfluidic immunoassay is realized by lateral flow and gold nanoparticle-based colorimetric detection of the target protein. The test image signal is acquired and analyzed using a commercial smartphone with an attached microlens and a 3D-printed chip-phone interface. The CRP-Chip was validated for detecting CRP in blood samples from chronic kidney disease patients and healthy subjects. The linear detection range of the CRP-Chip is up to 2 μg/mL and the detection limit is 54 ng/mL. The CRP-Chip test result yields high reproducibility and is consistent with the standard ELISA kit. A single CRP-Chip can perform the test in triplicate on a single chip within 15 min for less than 50 US cents of material cost. This CRP-Chip with attractive features of low-cost, fast test speed, and integrated easy operation with smartphones has the potential to enable future clinical PoC chronic disease diagnosis and risk stratification by parallel measurements of a panel of protein biomarkers.

  4. Processing window for femtosecond laser microsurgery and fluorescence imaging of an arterial tissue hosted in a microfluidic chip

    NASA Astrophysics Data System (ADS)

    Karimelahi, Samira; Li, Jianzhao; Herman, Peter R.

    2016-02-01

    We study the exposure limitations of femtosecond laser microsurgery and multiphoton imaging in a microfluidic chip environment, assessing damage thresholds at various interfaces as well as interference from bubble formation in the hosting solution. Both heat accumulation and incubation effects from multipulse laser exposures at 1-MHz repetition rate were evaluated. For demonstration, three microsurgery approaches of laser scribing, percussion drilling and trepanning were applied to arterial walls loaded in vitro in a lab-on-a-chip device. We report that deleterious effects from interface damage and microbubble formation can be avoided to offer laser processing windows for damage-free fluorescence imaging and precise microsurgery of live tissue hosted inside small microfluidic chambers.

  5. A coral-on-a-chip microfluidic platform enabling live-imaging microscopy of reef-building corals.

    PubMed

    Shapiro, Orr H; Kramarsky-Winter, Esti; Gavish, Assaf R; Stocker, Roman; Vardi, Assaf

    2016-03-04

    Coral reefs, and the unique ecosystems they support, are facing severe threats by human activities and climate change. Our understanding of these threats is hampered by the lack of robust approaches for studying the micro-scale interactions between corals and their environment. Here we present an experimental platform, coral-on-a-chip, combining micropropagation and microfluidics to allow direct microscopic study of live coral polyps. The small and transparent coral micropropagates are ideally suited for live-imaging microscopy, while the microfluidic platform facilitates long-term visualization under controlled environmental conditions. We demonstrate the usefulness of this approach by imaging coral micropropagates at previously unattainable spatio-temporal resolutions, providing new insights into several micro-scale processes including coral calcification, coral-pathogen interaction and the loss of algal symbionts (coral bleaching). Coral-on-a-chip thus provides a powerful method for studying coral physiology in vivo at the micro-scale, opening new vistas in coral biology.

  6. Continuous transfer of liquid metal droplets across a fluid-fluid interface within an integrated microfluidic chip.

    PubMed

    Gol, Berrak; Tovar-Lopez, Francisco J; Kurdzinski, Michael E; Tang, Shi-Yang; Petersen, Phred; Mitchell, Arnan; Khoshmanesh, Khashayar

    2015-06-07

    Micro scale liquid metal droplets have been hailed as the potential key building blocks of future micro-electro-mechanical systems (MEMS). However, most of the current liquid metal enabled systems involve millimeter scale droplets, which are manually injected onto the desired locations of the microchip. Despite its simplicity, this method is impractical for patterning large arrays or complex systems based on micro scale droplets. Here, we present a microfluidic chip, which integrates continuous generation of micro scale galinstan droplets in glycerol, and the hydrodynamic transfer of these droplets into sodium hydroxide (NaOH) solution. Observation via high-speed imaging along with computational fluid dynamics (CFD) analysis are utilised to comprehend the lateral migration of droplets from the glycerol to NaOH fluid. This platform is simple, can be readily integrated into other microfluidic systems, and creates flexibility by separating the continuous phase for droplet generation from the eventual target carrier fluid within a monolithic chip.

  7. DNA-library assembly programmed by on-demand nano-liter droplets from a custom microfluidic chip

    PubMed Central

    Tangen, Uwe; Minero, Gabriel Antonio S.; Sharma, Abhishek; Wagler, Patrick F.; Cohen, Rafael; Raz, Ofir; Marx, Tzipy; Ben-Yehezkel, Tuval; McCaskill, John S.

    2015-01-01

    Nanoscale synthetic biology can benefit from programmable nanoliter-scale processing of DNA in microfluidic chips if they are interfaced effectively to biochemical arrays such as microwell plates. Whereas active microvalve chips require complex fabrication and operation, we show here how a passive and readily fabricated microchip can be employed for customizable nanoliter scale pipetting and reaction control involving DNA. This recently developed passive microfluidic device, supporting nanoliter scale combinatorial droplet generation and mixing, is here used to generate a DNA test library with one member per droplet exported to addressed locations on microwell plates. Standard DNA assembly techniques, such as Gibson assembly, compatible with isothermal on-chip operation, are employed and checked using off-chip PCR and assembly PCR. The control of output droplet sequences and mixing performance was verified using dyes and fluorescently labeled DNA solutions, both on-chip and in external capillary channels. Gel electrophoresis of products and DNA sequencing were employed to further verify controlled combination and functional enzymatic assembly. The scalability of the results to larger DNA libraries is also addressed by combinatorial input expansion using sequential injection plugs from a multiwell plate. Hence, the paper establishes a proof of principle of the production of functional combinatorial mixtures at the nanoliter scale for one sequence per well DNA libraries. PMID:26221198

  8. Microfluidic chip with integrated electrical cell-impedance sensing for monitoring single cancer cell migration in three-dimensional matrixes.

    PubMed

    Nguyen, Tien Anh; Yin, Tsung-I; Reyes, Diego; Urban, Gerald A

    2013-11-19

    Cell migration has been recognized as one hallmark of malignant tumor progression. By integrating the method of electrical cell-substrate impedance sensing (ECIS) with the Boyden chamber design, the state-of-the-art techniques provide kinetic information about cell migration and invasion processes in three-dimensional (3D) extracellular matrixes. However, the information related to the initial stage of cell migration with single-cell resolution, which plays a unique role in the metastasis-invasion cascade of cancer, is not yet available. In this paper, we present a microfluidic device integrated with ECIS for investigating single cancer cell migration in 3D matrixes. Using microfluidics techniques without the requirement of physical connections to off-chip pneumatics, the proposed sensor chip can efficiently capture single cells on microelectrode arrays for sequential on-chip 2D or 3D cell culture and impedance measurement. An on-chip single-cell migration assay was successfully demonstrated within several minutes. Migration of single metastatic MDA-MB-231 cells in their initial stage can be monitored in real time; it shows a rapid change in impedance magnitude of approximately 10 Ω/s, whereas no prominent impedance change is observed for less-metastasis MCF-7 cells. The proposed sensor chip, allowing for a rapid and selective detection of the migratory properties of cancer cells at the single-cell level, could be applied as a new tool for cancer research.

  9. Multiscale variation-aware techniques for high-performance digital microfluidic lab-on-a-chip component placement.

    PubMed

    Liao, Chen; Hu, Shiyan

    2011-03-01

    The invention of microfluidic lab-on-a-chip alleviates the burden of traditional biochemical laboratory procedures which are often very expensive. Device miniaturization and increasing design complexity have mandated a shift in digital microfluidic lab-on-a-chip design from traditional manual design to computer-aided design (CAD) methodologies. As an important procedure in the lab-on-a-chip layout CAD, the lab-on-a-chip component placement determines the physical location and the starting time of each operation such that the overall completion time is minimized while satisfying nonoverlapping constraint, resource constraint, and scheduling constraint. In this paper, a multiscale variation-aware optimization technique based on integer linear programming is proposed for the lab-on-a-chip component placement. The simulation results demonstrate that without considering variations, our technique always satisfies the design constraints and largely outperforms the state-of-the-art approach, with up to 65.9% reduction in completion time. When considering variations, the variation-unaware design has the average yield of 2%, while our variation-aware technique always satisfies the yield constraint with only 7.7% completion time increase.

  10. On-Chip Microfluidic Components for In Situ Analysis, Separation, and Detection of Amino Acids

    NASA Technical Reports Server (NTRS)

    Zheng, Yun; Getty, Stephanie; Dworkin, Jason; Balvin, Manuel; Kotecki, Carl

    2013-01-01

    The Astrobiology Analytical Laboratory at GSFC has identified amino acids in meteorites and returned cometary samples by using liquid chromatography-electrospray ionization time-of-flight mass spectrometry (LCMS). These organic species are key markers for life, having the property of chirality that can be used to distinguish biological from non-biological amino acids. One of the critical components in the benchtop instrument is liquid chromatography (LC) analytical column. The commercial LC analytical column is an over- 250-mm-long and 4.6-mm-diameter stainless steel tube filled with functionized microbeads as stationary phase to separate the molecular species based on their chemistry. Miniaturization of this technique for spaceflight is compelling for future payloads for landed missions targeting astrobiology objectives. A commercial liquid chromatography analytical column consists of an inert cylindrical tube filled with a stationary phase, i.e., microbeads, that has been functionalized with a targeted chemistry. When analyte is sent through the column by a pressurized carrier fluid (typically a methanol/ water mixture), compounds are separated in time due to differences in chemical interactions with the stationary phase. Different species of analyte molecules will interact more strongly with the column chemistry, and will therefore take longer to traverse the column. In this way, the column will separate molecular species based on their chemistry. A lab-on-chip liquid analysis tool was developed. The microfluidic analytical column is capable of chromatographically separating biologically relevant classes of molecules based on their chemistry. For this analytical column, fabrication, low leak rate, and stationary phase incorporation of a serpentine microchannel were demonstrated that mimic the dimensions of a commercial LC column within a 5 10 1 mm chip. The microchannel in the chip has a 75- micrometer-diameter oval-shaped cross section. The serpentine

  11. A three dimensional thermoplastic microfluidic chip for robust cell capture and high resolution imaging

    PubMed Central

    Mottet, Guillaume; Perez-Toralla, Karla; Tulukcuoglu, Ezgi; Bidard, Francois-Clement; Pierga, Jean-Yves; Draskovic, Irena; Londono-Vallejo, Arturo; Descroix, Stephanie; Malaquin, Laurent; Louis Viovy, Jean

    2014-01-01

    We present a low cost microfluidic chip integrating 3D micro-chambers for the capture and the analysis of cells. This device has a simple design and a small footprint. It allows the implementation of standard biological protocols in a chip format with low volume consumption. The manufacturing process relies on hot-embossing of cyclo olefin copolymer, allowing the development of a low cost and robust device. A 3D design of microchannels was used to induce high flow velocity contrasts in the device and provide a selective immobilization. In narrow distribution channels, the liquid velocity induces a shear stress that overcomes adhesion forces and prevents cell immobilization or clogging. In large 3D chambers, the liquid velocity drops down below the threshold for cell attachment. The devices can be operated in a large range of input pressures and can even be handled manually using simple syringe or micropipette. Even at high flow injection rates, the 3D structures protect the captured cell from shear stress. To validate the performances of our device, we implemented immuno-fluorescence labeling and Fluorescence in Situ Hybridization (FISH) analysis on cancer cell lines and on a patient pleural effusion sample. FISH is a Food and Drug Administration approved cancer diagnostic technique that provides quantitative information about gene and chromosome aberration at the single cell level. It is usually considered as a long and fastidious test in medical diagnosis. This process can be easily implanted in our platform, and high resolution fluorescence imaging can be performed with reduced time and computer intensiveness. These results demonstrate the potential of this chip as a low cost, robust, and versatile tool adapted to complex and demanding protocols for medical diagnosis. PMID:25352942

  12. Surface modification of PDMS microfluidic devices by controlled sulfuric acid treatment and the application in chip electrophoresis.

    PubMed

    Gitlin, Leonid; Schulze, Philipp; Ohla, Stefan; Bongard, Hans-Josef; Belder, Detlev

    2015-02-01

    Herein, we present a straightforward surface modification technique for PDMS-based microfluidic devices. The method takes advantage of the high reactivity of concentrated sulfuric acid to enhance the surface properties of PDMS bulk material. This results in alteration of the surface morphology and chemical composition that is in-depth characterized by ATR-FTIR, EDX, SEM, and XPS. In comparison to untreated PDMS, modified substrates exhibit a significantly reduced diffusive uptake of small organic molecules while retaining its low electroosmotic properties. This was demonstrated by exposing the channels of a microfluidic device to concentrated rhodamine B solution followed by fluorescence microscopy. The surface modification procedure was used to improve chip-based electrophoretic separations. Separation efficiencies of FITC-labeled amines/amino acids obtained in treated and untreated PDMS-devices as well as in glass chips were compared. We obtained higher efficiencies in H2 SO4 treated PDMS chips compared to untreated ones but lower efficiencies than those obtained in commercial microfluidic glass devices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. A portable pressure pump for microfluidic lab-on-a-chip systems using a porous polydimethylsiloxane (PDMS) sponge.

    PubMed

    Cha, Kyoung Je; Kim, Dong Sung

    2011-10-01

    In this paper, we propose a novel portable and disposable pressure pump using a porous polydimethylsiloxane (PDMS) sponge and demonstrate its application to a microfluidic lab-on-a-chip. The porous PDMS sponge was simply fabricated by a sugar leaching technique based on capillary suction of pre-cured PDMS into lumps of sugar, thereby enabling us to achieve the porous PDMS sponge composed of interconnected micropores. To indicate the characteristics of the porous PDMS sponge and pump, we measured the average porosities of them whose values were 0.64 and 0.34, respectively. A stress-strain relationship of the fabricated portable pressure pump represented a linear behavior in the compressive strain range of 0 to 20%. Within this range, a pumping volume of the pressure pump could be linearly controlled by the compressed strain. Finally, the fabricated porous PDMS pump was successfully demonstrated as a portable pressure pump for a disposable microfluidic lab-on-a-chip for efficient detection of agglutination. The proposed portable pressure pump can be potentially applicable to various disposable microfluidic lab-on-a-chip systems.

  14. Adsorption and isolation of nucleic acids on cellulose magnetic beads using a three-dimensional printed microfluidic chip.

    PubMed

    Zhang, Lei; Deraney, Rachel N; Tripathi, Anubhav

    2015-11-01

    While advances in genomics have enabled sensitive and highly parallel detection of nucleic acid targets, the isolation and extraction of the nucleic acids remain a critical bottleneck in the workflow. We present here a simple 3D printed microfluidic chip that allows for the vortex and centrifugation free extraction of nucleic acids. This novel microfluidic chip utilizes the presence of a water and oil interface to filter out the lysate contaminants. The pure nucleic acids, while bound on cellulose particles, are magnetically moved across the oil layer. We demonstrated efficient and rapid extraction of spiked Human Papillomavirus (HPV) 18 plasmids in specimen transport medium, in under 15 min. An overall extraction efficiency of 61% is observed across a range of HPV plasmid concentrations (5 × 10(1) to 5 × 10(6) copies/100 μl). The magnetic, interfacial, and viscous drag forces inside the microgeometries of the chip are modeled. We have also developed a kinetics model for the adsorption of nucleic acids on cellulose functionalized superparamagnetic beads. We also clarify here the role of carrier nucleic acids in the adsorption and isolation of nucleic acids. Based on the various mechanistic insights detailed here, customized microfluidic devices can be designed to meet the range of current and emerging point of care diagnostics needs.

  15. A programmable and configurable multi-port System-on-Chip for stimulating electrokinetically-driven microfluidic devices.

    PubMed

    Lopez, Martha Salome; Gerstlauer, Andreas; Avila, Alfonso; Martinez-Chapa, Sergio O

    2011-01-01

    Recent research has demonstrated the use of microfluidic devices and electro-kinetics in areas such as medicine, genetics, embryology, epidemiology and pollution analysis, where manipulation of particles suspended in liquid media is required. Micro-fabrication technology has made it possible to increase system complexity and functionality by allowing integration of different processing and analysis stages in a single chip. However, fully integrated and autonomous microfluidic systems supporting ad-hoc stimulation have yet to be developed. This paper presents a flexible, configurable and programmable stimulator for electro-kinetically driven microfluidic devices. The stimulator is a dedicated System-on-Chip (SoC) architecture that generates sine, triangle, and sawtooth signals within a frequency range of 1 Hz to 20 MHz, capable of delivering single, dual, and superimposed waveforms, in a user defined test sequence for a selected time period. The system is designed to be integrated into complete, autonomous Lab-on-Chip, portable or implantable devices. As such, it is expected to help significantly advance current and future research on particle manipulation.

  16. Adsorption and isolation of nucleic acids on cellulose magnetic beads using a three-dimensional printed microfluidic chip

    PubMed Central

    Zhang, Lei; Deraney, Rachel N.; Tripathi, Anubhav

    2015-01-01

    While advances in genomics have enabled sensitive and highly parallel detection of nucleic acid targets, the isolation and extraction of the nucleic acids remain a critical bottleneck in the workflow. We present here a simple 3D printed microfluidic chip that allows for the vortex and centrifugation free extraction of nucleic acids. This novel microfluidic chip utilizes the presence of a water and oil interface to filter out the lysate contaminants. The pure nucleic acids, while bound on cellulose particles, are magnetically moved across the oil layer. We demonstrated efficient and rapid extraction of spiked Human Papillomavirus (HPV) 18 plasmids in specimen transport medium, in under 15 min. An overall extraction efficiency of 61% is observed across a range of HPV plasmid concentrations (5 × 101 to 5 × 106 copies/100 μl). The magnetic, interfacial, and viscous drag forces inside the microgeometries of the chip are modeled. We have also developed a kinetics model for the adsorption of nucleic acids on cellulose functionalized superparamagnetic beads. We also clarify here the role of carrier nucleic acids in the adsorption and isolation of nucleic acids. Based on the various mechanistic insights detailed here, customized microfluidic devices can be designed to meet the range of current and emerging point of care diagnostics needs. PMID:26734116

  17. Microfluidic and lab-on-a-chip preparation routes for organic nanoparticles and vesicular systems for nanomedicine applications.

    PubMed

    Capretto, Lorenzo; Carugo, Dario; Mazzitelli, Stefania; Nastruzzi, Claudio; Zhang, Xunli

    2013-11-01

    In recent years, advancements in the fields of microfluidic and lab-on-a-chip technologies have provided unique opportunities for the implementation of nanomaterial production processes owing to the miniaturisation of the fluidic environment. It has been demonstrated that microfluidic reactors offer a range of advantages compared to conventional batch reactors, including improved controllability and uniformity of nanomaterial characteristics. In addition, the fast mixing achieved within microchannels, and the predictability of the laminar flow conditions, can be leveraged to investigate the nanomaterial formation dynamics. In this article recent developments in the field of microfluidic production of nanomaterials for drug delivery applications are reviewed. The features that make microfluidic reactors a suitable technological platform are discussed in terms of controllability of nanomaterials production. An overview of the various strategies developed for the production of organic nanoparticles and colloidal assemblies is presented, focusing on those nanomaterials that could have an impact on nanomedicine field such as drug nanoparticles, polymeric micelles, liposomes, polymersomes, polyplexes and hybrid nanoparticles. The effect of microfluidic environment on nanomaterials formation dynamics, as well as the use of microdevices as tools for nanomaterial investigation is also discussed. © 2013 Elsevier B.V. All rights reserved.

  18. A lab-on-a-chip system for the development of complex assays using modular microfluidic components

    NASA Astrophysics Data System (ADS)

    Hlawatsch, Nadine; Klemm, Richard; Carstens, Cornelia; Brandst"tter, Thomas; Becker, Holger; Elbracht, Rudi; Gärtner, Claudia

    2012-03-01

    For complex biological or diagnostic assays, the development of an integrated microfluidic device can be difficult and error-prone. For this reason, a modular approach, using individual microfluidic functional modules for the different process steps, can be advantageous. However often the interconnection of the modules proves to be tedious and the peripheral instrumentation to drive the various modules is cumbersome and of large size. For this reason, we have developed an integrated instrument platform which has generic functionalities such as valves and pumps, heating zones for continuous-flow PCR, moveable magnets for bead-based assays and an optical detection unit build into the instrument. The instrument holds a titerplate-sized carrier in which up to four microscopy-slide sized microfluidic modules can be clipped in. This allows for developing and optimizing individual assay steps without the need to modify the instrument or generate a completely new microfluidic cartridge. As a proof-of-concept, the automated sample processing of liquor or blood culture in microfluidic structures for detection of currently occuring Neisseria meningitidis strains was carried out. This assay involves the extraction of bacterial DNA, the fluorescent labeling, amplification using PCR as well as the hybridization of the DNA molecules in three-dimensional capture sites spotted into a microchannel. To define the assay sensitivity, chip modules were tested with bacteria spiked samples of different origins and results were controlled by conventional techniques. For liquor or blood culture, the presence of 200 bacteria was detected within 1 hour.

  19. Fabrication of Functionalized Double-Lamellar Multifunctional Envelope-Type Nanodevices Using a Microfluidic Chip with a Chaotic Mixer Array

    PubMed Central

    Kitazoe, Katsuma; Park, Yeon-Su; Kaji, Noritada; Okamoto, Yukihiro; Tokeshi, Manabu; Kogure, Kentaro; Harashima, Hideyoshi; Baba, Yoshinobu

    2012-01-01

    Multifunctional envelope-type nanodevices (MENDs) are very promising non-viral gene delivery vectors because they are biocompatible and enable programmed packaging of various functional elements into an individual nanostructured liposome. Conventionally MENDs have been fabricated by complicated, labor-intensive, time-consuming bulk batch methods. To avoid these problems in MEND fabrication, we adopted a microfluidic chip with a chaotic mixer array on the floor of its reaction channel. The array was composed of 69 cycles of the staggered chaotic mixer with bas-relief structures. Although the reaction channel had very large Péclet numbers (>105) favorable for laminar flows, its chaotic mixer array led to very small mixing lengths (<1.5 cm) and that allowed homogeneous mixing of MEND precursors in a short time. Using the microfluidic chip, we fabricated a double-lamellar MEND (D-MEND) composed of a condensed plasmid DNA core and a lipid bilayer membrane envelope as well as the D-MEND modified with trans-membrane peptide octaarginine. Our lab-on-a-chip approach was much simpler, faster, and more convenient for fabricating the MENDs, as compared with the conventional bulk batch approaches. Further, the physical properties of the on-chip-fabricated MENDs were comparable to or better than those of the bulk batch-fabricated MENDs. Our fabrication strategy using microfluidic chips with short mixing length reaction channels may provide practical ways for constructing more elegant liposome-based non-viral vectors that can effectively penetrate all membranes in cells and lead to high gene transfection efficiency. PMID:22723929

  20. Fabrication of functionalized double-lamellar multifunctional envelope-type nanodevices using a microfluidic chip with a chaotic mixer array.

    PubMed

    Kitazoe, Katsuma; Park, Yeon-Su; Kaji, Noritada; Okamoto, Yukihiro; Tokeshi, Manabu; Kogure, Kentaro; Harashima, Hideyoshi; Baba, Yoshinobu

    2012-01-01

    Multifunctional envelope-type nanodevices (MENDs) are very promising non-viral gene delivery vectors because they are biocompatible and enable programmed packaging of various functional elements into an individual nanostructured liposome. Conventionally MENDs have been fabricated by complicated, labor-intensive, time-consuming bulk batch methods. To avoid these problems in MEND fabrication, we adopted a microfluidic chip with a chaotic mixer array on the floor of its reaction channel. The array was composed of 69 cycles of the staggered chaotic mixer with bas-relief structures. Although the reaction channel had very large Péclet numbers (>10(5)) favorable for laminar flows, its chaotic mixer array led to very small mixing lengths (<1.5 cm) and that allowed homogeneous mixing of MEND precursors in a short time. Using the microfluidic chip, we fabricated a double-lamellar MEND (D-MEND) composed of a condensed plasmid DNA core and a lipid bilayer membrane envelope as well as the D-MEND modified with trans-membrane peptide octaarginine. Our lab-on-a-chip approach was much simpler, faster, and more convenient for fabricating the MENDs, as compared with the conventional bulk batch approaches. Further, the physical properties of the on-chip-fabricated MENDs were comparable to or better than those of the bulk batch-fabricated MENDs. Our fabrication strategy using microfluidic chips with short mixing length reaction channels may provide practical ways for constructing more elegant liposome-based non-viral vectors that can effectively penetrate all membranes in cells and lead to high gene transfection efficiency.

  1. Rapid and Low-Cost CRP Measurement by Integrating a Paper-Based Microfluidic Immunoassay with Smartphone (CRP-Chip)

    PubMed Central

    Dong, Meili; Wu, Jiandong; Ma, Zimin; Peretz-Soroka, Hagit; Zhang, Michael; Komenda, Paul; Tangri, Navdeep; Liu, Yong; Rigatto, Claudio; Lin, Francis

    2017-01-01

    Traditional diagnostic tests for chronic diseases are expensive and require a specialized laboratory, therefore limiting their use for point-of-care (PoC) testing. To address this gap, we developed a method for rapid and low-cost C-reactive protein (CRP) detection from blood by integrating a paper-based microfluidic immunoassay with a smartphone (CRP-Chip). We chose CRP for this initial development because it is a strong biomarker of prognosis in chronic heart and kidney disease. The microfluidic immunoassay is realized by lateral flow and gold nanoparticle-based colorimetric detection of the target protein. The test image signal is acquired and analyzed using a commercial smartphone with an attached microlens and a 3D-printed chip–phone interface. The CRP-Chip was validated for detecting CRP in blood samples from chronic kidney disease patients and healthy subjects. The linear detection range of the CRP-Chip is up to 2 μg/mL and the detection limit is 54 ng/mL. The CRP-Chip test result yields high reproducibility and is consistent with the standard ELISA kit. A single CRP-Chip can perform the test in triplicate on a single chip within 15 min for less than 50 US cents of material cost. This CRP-Chip with attractive features of low-cost, fast test speed, and integrated easy operation with smartphones has the potential to enable future clinical PoC chronic disease diagnosis and risk stratification by parallel measurements of a panel of protein biomarkers. PMID:28346363

  2. Can we get a better knowledge on dissolution processes in chalk by using microfluidic chips?

    NASA Astrophysics Data System (ADS)

    Neuville, Amélie; Minde, Mona; Renaud, Louis; Vinningland, Jan Ludvig; Dysthe, Dag Kristian; Hiorth, Aksel

    2017-04-01

    mostly occurs at the surface of the sample. The reacting chalk surface is observed in situ by stereomicroscopy and by interferometry. The dissolution velocities are highly heterogeneous. To identify the mineral change of the surface, a posteriori measurements using field emission scanning electron microscopy (FE-SEM), and energy dispersive X-ray spectroscopy (EDS). [1] Neuville et al, 2016, Xurography for microfluidics on a reactive solid, Lab on Chip, DOI: 10.1039/c6lc01253a

  3. Enantioselective reaction monitoring utilizing two-dimensional heart-cut liquid chromatography on an integrated microfluidic chip.

    PubMed

    Lotter, Carsten; Poehler, Elisabeth; Heiland, Josef J; Mauritz, Laura; Belder, Detlev

    2016-11-29

    Chip-integrated, two-dimensional high performance liquid chromatography is introduced to monitor enantioselective continuous micro-flow synthesis. The herein described development of the first two-dimensional HPLC-chip was realized by the integration of two different columns packed with reversed-phase and chiral stationary phase material on a microfluidic glass chip, coupled to mass spectrometry. Directed steering of the micro-flows at the joining transfer cross enabled a heart-cut operation mode to transfer the chiral compound of interest from the first to the second chromatographic dimension. This allows for an interference-free determination of the enantiomeric excess by seamless hyphenation to electrospray mass spectrometry. The application for rapid reaction optimization at micro-flow conditions is exemplarily shown for the asymmetric organocatalytic continuous micro-flow synthesis of warfarin.

  4. Beating heart on a chip: a novel microfluidic platform to generate functional 3D cardiac microtissues.

    PubMed

    Marsano, Anna; Conficconi, Chiara; Lemme, Marta; Occhetta, Paola; Gaudiello, Emanuele; Votta, Emiliano; Cerino, Giulia; Redaelli, Alberto; Rasponi, Marco

    2016-02-07

    In the past few years, microfluidic-based technology has developed microscale models recapitulating key physical and biological cues typical of the native myocardium. However, the application of controlled physiological uniaxial cyclic strains on a defined three-dimension cellular environment is not yet possible. Two-dimension mechanical stimulation was particularly investigated, neglecting the complex three-dimensional cell-cell and cell-matrix interactions. For this purpose, we developed a heart-on-a-chip platform, which recapitulates the physiologic mechanical environment experienced by cells in the native myocardium. The device includes an array of hanging posts to confine cell-laden gels, and a pneumatic actuation system to induce homogeneous uniaxial cyclic strains to the 3D cell constructs during culture. The device was used to generate mature and highly functional micro-engineered cardiac tissues (μECTs), from both neonatal rat and human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM), strongly suggesting the robustness of our engineered cardiac micro-niche. Our results demonstrated that the cyclic strain was effectively highly uniaxial and uniformly transferred to cells in culture. As compared to control, stimulated μECTs showed superior cardiac differentiation, as well as electrical and mechanical coupling, owing to a remarkable increase in junction complexes. Mechanical stimulation also promoted early spontaneous synchronous beating and better contractile capability in response to electric pacing. Pacing analyses of hiPSC-CM constructs upon controlled administration of isoprenaline showed further promising applications of our platform in drug discovery, delivery and toxicology fields. The proposed heart-on-a-chip device represents a relevant step forward in the field, providing a standard functional three-dimensional cardiac model to possibly predict signs of hypertrophic changes in cardiac phenotype by mechanical and biochemical co-stimulation.

  5. Chemical stimulation of the Arabidopsis thaliana root using multi-laminar flow on a microfluidic chip.

    PubMed

    Meier, Matthias; Lucchetta, Elena M; Ismagilov, Rustem F

    2010-08-21

    In this article, we developed a "plant on a chip" microfluidic platform that can control the local chemical environment around live roots of Arabidopsis thaliana with high spatial resolution using multi-laminar flow. We characterized the flow profile around the Arabidopsis root, and verified that the shear forces within the device ( approximately 10 dyne cm(-2)) did not impede growth of the roots. Our platform was able to deliver stimuli to the root at a spatial resolution of 10-800 microm. Further, the platform was validated by exposing desired regions of the root with a synthetic auxin derivative, 2,4-dichlorophenoxyacetic acid (2,4-D), and its inhibitor N-1-naphthylphthalamic acid (NPA). The response to the stimuli was observed using a DR5::GFP Arabidopsis line, where GFP expression is coupled to the auxin response regulator DR5. GFP expression in the root matched the position of the flow-focused stream containing 2,4-D. When the regions around the 2,4-D stimulus were exposed to the auxin transport inhibitor NPA, the active and passive transport mechanisms of auxin could be differentiated, as NPA blocks active cell-to-cell transport of auxin. Finally, we demonstrated that local 2,4-D stimulation in a approximately 10 microm root segment enhanced morphological changes such as epidermal hair growth. These experiments were proof-of-concept and agreed with the results expected based on known root biology, demonstrating that this "root on a chip" platform can be used to test how root development is affected by any chemical component of interest, including nitrogen, phosphate, salts, and other plant hormones.

  6. Biomimetic postcapillary expansions for enhancing rare blood cell separation on a microfluidic chip.

    PubMed

    Jain, Abhishek; Munn, Lance L

    2011-09-07

    Blood cells naturally auto-segregate in postcapillary venules, with the erythrocytes (red blood cells, RBCs) aggregating near the axis of flow and the nucleated cells (NCs)--which include leukocytes, progenitor cells and, in cancer patients, circulating tumor cells--marginating toward the vessel wall. We have used this principle to design a microfluidic device that extracts nucleated cells (NCs) from whole blood. Fabricated using polydimethylsiloxane (PDMS) soft lithography, the biomimetic cell extraction device consists of rectangular microchannels that are 20-400 μm wide, 11 μm deep and up to 2 cm long. The key design feature is the use of repeated expansions/contractions of triangular geometry mimicking postcapillary venules, which enhance margination and optimize the extraction. The device operates on unprocessed whole blood and is able to extract 94 ± 4.5% of NCs with 45.75 ± 2.5-fold enrichment in concentration at a rate of 5 nl s(-1). The device eliminates the need to preprocess blood via centrifugation or RBC lysis, and is ready to be implemented as the initial stage of lab-on-a-chip devices that require enriched nucleated cells. The potential downstream applications are numerous, encompassing all preclinical and clinical assays that operate on enriched NC populations and include on-chip flow cytometry (A. Y. Fu et al., Anal. Chem., 2002, 74, 2451-2457; A. Y. Fu et al., Nat. Biotechnol., 1999, 17, 1109-1111), genetic analyses (M. M. Wang et al., Nat. Biotechnol., 2005, 23, 83-87; L. C. Waters et al., Anal. Chem., 1998, 70, 5172-5176) and circulating tumor cell extraction (S. Nagrath et al., Nature, 2007, 450, 1235-1241; S. L. Stott et al., Proc. Natl. Acad. Sci. U. S. A., 2010, 18392-18397; H. K. Lin et al., Clin. Cancer Res., 2010, 16, 5011-5018).

  7. Gradient Static-Strain Stimulation in a Microfluidic Chip for 3D Cellular Alignment

    PubMed Central

    Hsieh, Hsin-Yi; Camci-Unal, Gulden; Huang, Tsu-Wei; Liao, Ronglih; Chen, Tsung-Ju; Paul, Arghya; Tseng, Fan-Gang; Khademhosseini, Ali

    2014-01-01

    Cell alignment is a critical factor to govern cellular behavior and function for various tissue engineering applications ranging from cardiac to neural regeneration. In addition to physical geometry, strain is a crucial parameter to manipulate cellular alignment for functional tissue formation. In this paper, we introduce a simple approach to generate a range of gradient static strains without external mechanical control for the stimulation of cellular behavior within 3D biomimetic hydrogel microenvironments. A glass-supported microfluidic chip with a convex flexible polydimethylsiloxane (PDMS) membrane on the top was employed for loading the cells suspended in a prepolymer solution. Following UV crosslinking through a photomask with a concentric circular pattern, the cell-laden hydrogels were formed in a height gradient from the center (maximum) to the boundary (minimum). When the convex PDMS membrane retracted back to a flat surface, it applied compressive gradient forces on the cell-laden hydrogels. The concentric circular hydrogel patterns confined the direction of hydrogel elongation, and the compressive strain on the hydrogel therefore resulted in elongation stretch in the radial direction to guide cell alignment. NIH3T3 cells were cultured in the chip for 3 days with compressive strains that varied from ~65% (center) to ~15% (boundary) on hydrogels. We found that the hydrogel geometry dominated the cell alignment near the outside boundary, where cells aligned along the circular direction, and the compressive strain dominated the cell alignment near the center, where cells aligned radially. This study developed a new and simple approach to facilitate cellular alignment based on hydrogel geometry and strain stimulation for tissue engineering applications. This platform offers unique advantages and is significantly different than the existing approaches owing to the fact that gradient generation was accomplished in a miniature device without using an external

  8. A rapid and sensitive method for hydroxyl radical detection on a microfluidic chip using an N-doped porous carbon nanofiber modified pencil graphite electrode.

    PubMed

    Ouyang, Jun; Li, Zhong-Qiu; Zhang, Jing; Wang, Chen; Wang, Jiong; Xia, Xing-Hua; Zhou, Guo-Jun

    2014-07-07

    Hydroxyl radicals (˙OH) play an important role in human diseases. Traditional detection methods are time consuming and require expensive instruments. Here, we present a simple and sensitive method for the detection of hydroxyl radicals on a microfluidic chip using an electrochemical technique. Aniline monomer is electrochemically polymerized on the surface of a pencil graphite electrode and carbonized at 800 °C. The resulting N-doped porous carbon nanofiber-modified pencil graphite electrode is embedded into a microfluidic chip directly as a working electrode. 4-Hydroxybenzoic acid (4-HBA) is selected as the trapping agent owing to its unique 3,4-DHBA product and high trapping efficiency. A low detection limit of 1.0 × 10(-6) M is achieved on the microfluidic chip. As a demonstration, the microfluidic chip is successfully utilized for the detection of ˙OH in cigarette smoke. The strong π-π stacking and hydrophobic interactions between the nitrogen-doped carbon materials and the pencil graphite make the modified electrode well-suited for the microfluidic chip.

  9. NeuroChip: A Microfluidic Electrophysiological Device for Genetic and Chemical Biology Screening of Caenorhabditis elegans Adult and Larvae

    PubMed Central

    Hu, Chunxiao; Dillon, James; Kearn, James; Murray, Caitriona; O’Connor, Vincent; Holden-Dye, Lindy; Morgan, Hywel

    2013-01-01

    Genetic and chemical biology screens of C. elegans have been of enormous benefit in providing fundamental insight into neural function and neuroactive drugs. Recently the exploitation of microfluidic devices has added greater power to this experimental approach providing more discrete and higher throughput phenotypic analysis of neural systems. Here we make a significant addition to this repertoire through the design of a semi-automated microfluidic device, NeuroChip, which has been optimised for selecting worms based on the electrophysiological features of the pharyngeal neural network. We demonstrate this device has the capability to sort mutant from wild-type worms based on high definition extracellular electrophysiological recordings. NeuroChip resolves discrete differences in excitatory, inhibitory and neuromodulatory components of the neural network from individual animals. Worms may be fed into the device consecutively from a reservoir and recovered unharmed. It combines microfluidics with integrated electrode recording for sequential trapping, restraining, recording, releasing and recovering of C. elegans. Thus mutant worms may be selected, recovered and propagated enabling mutagenesis screens based on an electrophysiological phenotype. Drugs may be rapidly applied during the recording thus permitting compound screening. For toxicology, this analysis can provide a precise description of sub-lethal effects on neural function. The chamber has been modified to accommodate L2 larval stages showing applicability for small size nematodes including parasitic species which otherwise are not tractable to this experimental approach. We also combine NeuroChip with optogenetics for targeted interrogation of the function of the neural circuit. NeuroChip thus adds a new tool for exploitation of C. elegans and has applications in neurogenetics, drug discovery and neurotoxicology. PMID:23717588

  10. Real-time machine vision FPGA implementation for microfluidic monitoring on Lab-on-Chips.

    PubMed

    Sotiropoulou, Calliope-Louisa; Voudouris, Liberis; Gentsos, Christos; Demiris, Athanasios M; Vassiliadis, Nikolaos; Nikolaidis, Spyridon

    2014-04-01

    A machine vision implementation on a field-programmable gate array (FPGA) device for real-time microfluidic monitoring on Lab-On-Chips is presented in this paper. The machine vision system is designed to follow continuous or plug flows, for which the menisci of the fluids are always visible. The system discriminates between the front or "head" of the flow and the back or "tail" and is able to follow flows with a maximum speed of 20 mm/sec in circular channels of a diameter of 200 μm (corresponding to approx. 60 μl/sec ). It is designed to be part of a complete Point-of-Care system, which will be portable and operate in non-ideal laboratory conditions. Thus, it is able to cope with noise due to lighting conditions and small LoC displacements during the experiment execution. The machine vision system can be used for a variety of LoC devices, without the need for fiducial markers (such as redundancy patterns) for its operation. The underlying application requirements called for a complete hardware implementation. The architecture uses a variety of techniques to improve performance and minimize memory access requirements. The system input is 8 bit grayscale uncompressed video of up to 1 Mpixel resolution. The system uses an operating frequency of 170 Mhz and achieves a computational time of 13.97 ms (worst case), which leads to a throughput of 71.6 fps for 1 Mpixel video resolution.

  11. An integrated microfluidic chip system for single-cell secretion profiling of rare circulating tumor cells.

    PubMed

    Deng, Yuliang; Zhang, Yu; Sun, Shuai; Wang, Zhihua; Wang, Minjiao; Yu, Beiqin; Czajkowsky, Daniel M; Liu, Bingya; Li, Yan; Wei, Wei; Shi, Qihui

    2014-12-16

    Genetic and transcriptional profiling, as well as surface marker identification of single circulating tumor cells (CTCs) have been demonstrated. However, quantitatively profiling of functional proteins at single CTC resolution has not yet been achieved, owing to the limited purity of the isolated CTC populations and a lack of single-cell proteomic approaches to handle and analyze rare CTCs. Here, we develop an integrated microfluidic system specifically designed for streamlining isolation, purification and single-cell secretomic profiling of CTCs from whole blood. Key to this platform is the use of photocleavable ssDNA-encoded antibody conjugates to enable a highly purified CTC population with <75 'contaminated' blood cells. An enhanced poly-L-lysine barcode pattern is created on the single-cell barcode chip for efficient capture rare CTC cells in microchambers for subsequent secreted protein profiling. This system was extensively evaluated and optimized with EpCAM-positive HCT116 cells seeded into whole blood. Patient blood samples were employed to assess the utility of the system for isolation, purification and single-cell secretion profiling of CTCs. The CTCs present in patient blood samples exhibit highly heterogeneous secretion profile of IL-8 and VEGF. The numbers of secreting CTCs are found not in accordance with CTC enumeration based on immunostaining in the parallel experiments.

  12. Construction and operation of a microrobot based on magnetotactic bacteria in a microfluidic chip

    PubMed Central

    Ma, Qiufeng; Chen, Changyou; Wei, Shufeng; Chen, Chuanfang; Wu, Long-Fei; Song, Tao

    2012-01-01

    Magnetotactic bacteria (MTB) are capable of swimming along magnetic field lines. This unique feature renders them suitable in the development of magnetic-guided, auto-propelled microrobots to serve in target molecule separation and detection, drug delivery, or target cell screening in a microfluidic chip. The biotechnology to couple these bacteria with functional loads to form microrobots is the critical point in its application. Although an immunoreaction approach to attach functional loads to intact MTB was suggested, details on its realization were hardly mentioned. In the current paper, MTB-microrobots were constructed by attaching 2 μm diameter microbeads to marine magnetotactic ovoid MO-1 cells through immunoreactions. These microrobots were controlled using a special control and tracking system. Experimental results prove that the attachment efficiency can be improved to ∼30% via an immunoreaction. The motility of the bacteria attached with different number of loads was also assessed. The results show that MTB can transport one load at a velocity of ∼21 μm/s and still move and survive for over 30 min. The control and tracking system is fully capable of directing and monitoring the movement of the MTB-microrobots. The rotating magnetic fields can stop the microrobots by trapping them as they swim within a circular field with a controllable size. The system has potential use in chemical analyses and medical diagnoses using biochips as well as in nano/microscale transport. PMID:22655018

  13. Urinary micro-RNA biomarker detection using capped gold nanoslit SPR in a microfluidic chip.

    PubMed

    Mousavi, Mansoureh Z; Chen, Huai-Yi; Lee, Kuang-Li; Lin, Heng; Chen, Hsi-Hsien; Lin, Yuh-Feng; Wong, Chung-Shun; Li, Hsiao Fen; Wei, Pei-Kuen; Cheng, Ji-Yen

    2015-06-21

    Successful diagnosis and treatment of many diseases depends on the availability of sensitive, reliable and low cost tools for the detection of the biomarkers associated with the diseases. Simple methods that use non-invasive biological samples are especially suitable for the deployment in the clinical environment. In this paper we demonstrate the application of a method that employs a capped gold nanoslit surface plasmon resonance (SPR) sensor and a microfluidic chip for the detection of a urinary nucleic acid biomarker in clinical samples. This method detects low concentrations of the biomarker in a relatively large volume (∼1 mL) of the sample. The method utilizes magnetic nanoparticles (MNPs) for the isolation of target molecules and signal enhancement in conjunction with surface plasmon resonance (SPR) on capped gold nanoslits. The ability of the method to detect urinary miRNA-16-5p in AKI patients was tested and the result was compared with the data obtained with the polymerase chain reaction (PCR). miRNA-16-5p has been found to be a specific and noninvasive biomarker for acute kidney injury (AKI). Our method allows the detection of the biomarker in the urine of AKI patients without amplification and labeling of the target molecules.

  14. [New technique for nanoparticle capillary electrophoresis/microfluidic chip and its uses in enantioselective separation].

    PubMed

    Chen, Jie; Ding, Guosheng; Yue, Chunyue; Tang, Anna

    2012-01-01

    Nanoparticles have been widely used in separation science due to their large specific surface area and good biocompatibility. Nanoparticle capillary electrophoresis (CE)/microfluidic chip (MC) technique is the hybrid of nanomaterial and the CE/MC technique. By being adsorbed or bonded onto the inner surface of the capillary, the nanoparticles can interact with the analytes as stationary phase. As a kind of separation medium, the nanoparticles can also participate in the separation process acting as a pseudostationary phase (PSP) to improve the separation efficiency and selectivity. Chirality is one of the intrinsic characters of the nature. It is important to develop the novel, fast, highly efficient and sensitive chiral separation technique in many research areas, such as stereoselective synthesis of enantiomers, pharmacology, chiral compounds purity check and environment monitoring. Herein, the recent applications of different types of nanoparticles such as polymer nanoparticles, magnetic nanoparticles, gold nanoparticles and carbon nanotubes in enantioseparation by CE/MC are reviewed, and the future developments in this area are also prospected.

  15. A microfluidic reactor for rapid, low-pressure proteolysis with on-chip electrospray ionization.

    PubMed

    Liuni, Peter; Rob, Tamanna; Wilson, Derek J

    2010-02-01

    A microfluidic reactor that enables rapid digestion of proteins prior to on-line analysis by electrospray ionization mass spectrometry (ESI-MS) is introduced. The device incorporates a wide (1.5 cm), shallow (10 microm) reactor 'well' that is functionalized with pepsin-agarose, a design that facilitates low-pressure operation and high clogging resistance. Electrospray ionization is carried out directly from a short metal capillary integrated into the chip outlet. Fabrication, involving laser ablation of polymethyl methacrylate (PMMA), is exceedingly straightforward and inexpensive. High sequence coverage spectra of myoglobin (Mb), ubiquitin (Ub) and bovine serum albumin (BSA) digests were obtained after <4 s of residence time in the reactor. Stress testing showed little loss of performance over approximately 2 h continuous use at high flow rates (30 microL/min). The device provides a convenient platform for a range of applications in proteomics and structural biology, i.e. to enable high-throughput workflows or to limit back-exchange in spatially resolved hydrogen/deuterium exchange (HDX) experiments. Copyright 2010 John Wiley & Sons, Ltd.

  16. Phenotype Transformation of Aortic Valve Interstitial Cells Due to Applied Shear Stresses Within a Microfluidic Chip.

    PubMed

    Wang, Xinmei; Lee, Joohyung; Ali, Mir; Kim, Jungkyu; Lacerda, Carla M R

    2017-06-15

    Despite valvular heart diseases constituting a significant medical problem, the acquisition of information describing their pathophysiology remains difficult. Due to valvular size, role and location within the body, there is a need for in vitro systems that can recapitulate disease onset and progression. This study combines the development of an in vitro model and its application in the mechanical stimulation of valvular cell transformation. Specifically, porcine aortic valvular interstitial cells (PAVIC) were cultured on polydimethylsiloxane microfluidic devices with or without exposure to shear stresses. Mechanobiological responses of valvular interstitial cells were evaluated at shear stresses ranging from 0 to 4.26 dyn/cm(2). When flow rates were higher than 0.78 dyn/cm(2), cells elongated and aligned with the flow direction. In addition, we found that shear stress enhanced the formation of focal adhesions and up-regulated PAVIC transformation, assessed by increased expression of α-smooth muscle actin and transforming growth factor β. This study reveals a link between the action of shear forces, cell phenotype transformation and focal adhesion formation. This constitutes the first step towards the development of co-cultures (interstitial-endothelial cells) on organ-on-a-chip devices, which will enable studies of the signaling pathways regulating force-induced valvular degeneration in microtissues and potential discovery of valvular degeneration therapies.

  17. Isolation of motile spermatozoa with a microfluidic chip having a surface-modified microchannel.

    PubMed

    Huang, Hong-Yuan; Wu, Tsung-Lin; Huang, Hung-Ru; Li, Chin-Jung; Fu, Hui-Ting; Soong, Yung-Kuei; Lee, Ming-Yih; Yao, Da-Jeng

    2014-02-01

    Conventional methods to prepare sperm have been amenable to the investigation of outcomes such as rates of recovery and conventional semen parameters. The standard preparation of sperm for assisted reproduction is criticized for its centrifugation steps, which might either recover motile sperm in variable proportions or increase the probability of damage to sperm DNA. An microfluidic system was designed to separate motile sperm according to a design whereby nonmotile spermatozoa and debris flow along their initial streamlines and exit through one outlet-up, whereas motile spermatozoa have an opportunity to swim into a parallel stream and to exit through a separate outlet-down. This chip was fabricated by microelectromechanical systems technology with polydimethylsiloxane molding. The hydrophilic surface, coated with poly (ethanediol) methyl ether methacrylate, exhibits enduring stability maintained for the microchannel. Microscopic examination and fluorescent images showed that the motility of sperm varied with the laminar streams. To confirm the sorting, we identified and quantified the proportions of live and dead sperm before and after sorting with flow cytometric analysis. The results on the viability of a sample demonstrated the increased quality of sperm after sorting and collection in the outlet reservoir. The counted ratio of live sperm revealed the quantity and efficiency of the sorted sperm.

  18. Construction and operation of a microrobot based on magnetotactic bacteria in a microfluidic chip.

    PubMed

    Ma, Qiufeng; Chen, Changyou; Wei, Shufeng; Chen, Chuanfang; Wu, Long-Fei; Song, Tao

    2012-06-01

    Magnetotactic bacteria (MTB) are capable of swimming along magnetic field lines. This unique feature renders them suitable in the development of magnetic-guided, auto-propelled microrobots to serve in target molecule separation and detection, drug delivery, or target cell screening in a microfluidic chip. The biotechnology to couple these bacteria with functional loads to form microrobots is the critical point in its application. Although an immunoreaction approach to attach functional loads to intact MTB was suggested, details on its realization were hardly mentioned. In the current paper, MTB-microrobots were constructed by attaching 2 μm diameter microbeads to marine magnetotactic ovoid MO-1 cells through immunoreactions. These microrobots were controlled using a special control and tracking system. Experimental results prove that the attachment efficiency can be improved to ∼30% via an immunoreaction. The motility of the bacteria attached with different number of loads was also assessed. The results show that MTB can transport one load at a velocity of ∼21 μm/s and still move and survive for over 30 min. The control and tracking system is fully capable of directing and monitoring the movement of the MTB-microrobots. The rotating magnetic fields can stop the microrobots by trapping them as they swim within a circular field with a controllable size. The system has potential use in chemical analyses and medical diagnoses using biochips as well as in nano/microscale transport.

  19. Chitosan microgels obtained by on-chip crosslinking reaction employing a microfluidic device

    NASA Astrophysics Data System (ADS)

    Zamora-Mora, Vanessa; Velasco, Diego; Hernández, Rebeca; Mijangos, Carmen

    2014-12-01

    In the present work, we report on the preparation of microgels of chitosan crosslinked with sodium tripolyphosphate (TPP) employing the microfluidics technique (MF). To achieve this, several flow focusing geometries were designed and tested. As a first step, a two-inlet flow focusing geometry was employed to emulsify chitosan and the crosslinking reaction was carried out offchip. This procedure did not allow separating the resulting chitosan microgels due to an incomplete crosslinking reaction. A crosslinking reaction on-chip was studied as an alternative. A four-inlet flow focusing geometrywas designed in which three dispersed phases, chitosan 0.25% (w/v), TPP 0.05% (w/v) and acetic acid 1% (v/v) and an continuous phase mineral oil + Span 80 (3% w/v) were employed. The flow rates for the continuous phase were varied from 6.7 to 11.7 μL/min and chitosan microgels were successfully obtained with average diameters from 68 to 42 μm. The average size of the microgels outside the MF device decreased up to ~21% with respect to their size inside the MF device due to partial expulsion of water from the microgels when complete gelation occurred.

  20. High-performance fluorescence-encoded magnetic microbeads as microfluidic protein chip supports for AFP detection.

    PubMed

    Gong, Xiaoqun; Yan, Huan; Yang, Jiumin; Wu, Yudong; Zhang, Jian; Yao, Yingyi; Liu, Ping; Wang, Huiquan; Hu, Zhidong; Chang, Jin

    2016-10-05

    Fluorescence-encoded magnetic microbeads (FEMMs), with the fluorescence encoding ability of quantum dots (QDs) and magnetic enrichment and separation functions of Fe3O4 nanoparticles, have been widely used for multiple biomolecular detection as microfluidic protein chip supports. However, the preparation of FEMMs with long-term fluorescent encoding and immunodetection stability is still a challenge. In this work, we designed a novel high-temperature chemical swelling strategy. The QDs and Fe3O4 nanoparticles were effectively packaged into microbeads via the thermal motion of the polymer chains and the hydrophobic interaction between the nanoparticles and microbeads. The FEMMs obtained a highly uniform fluorescent property and long-term encoding and immunodetection stability and could be quickly magnetically separated and enriched. Then, the QD-encoded magnetic microbeads were applied to alpha fetoprotein (AFP) detection via sandwich immunoreaction. The properties of the encoded microspheres were characterized using a self-designed detecting apparatus, and the target molecular concentration in the sample was also quantified. The results suggested that the high-performance FEMMs have great potential in the field of biomolecular detection. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Convenient quantification of methanol concentration detection utilizing an integrated microfluidic chip

    PubMed Central

    Wang, Yao-Nan; Yang, Ruey-Jen; Ju, Wei-Jhong; Wu, Ming-Chang; Fu, Lung-Ming

    2012-01-01

    A rapid and simple technique is proposed for methanol concentration detection using a PMMA (Polymethyl-Methacrylate) microfluidic chip patterned using a commercially available CO2 laser scriber. In the proposed device, methanol and methanol oxidase (MOX) are injected into a three-dimensional circular chamber and are mixed via a vortex stirring effect. The mixture is heated to prompt the formation of formaldehyde and is flowed into a rectangular chamber, to which fuchsin-sulphurous acid is then added. Finally, the microchip is transferred to a UV spectrophotometer for methanol detection purposes. The experimental results show that a correlation coefficient of R2 = 0.9940 is obtained when plotting the optical density against the methanol concentration for samples and an accuracy as high as 93.1% are compared with the determined by the high quality gas chromatography with concentrations in the range of 2 ∼ 100 ppm. The methanol concentrations of four commercial red wines are successfully detected using the developed device. Overall, the results show that the proposed device provides a rapid and accurate means of detecting the methanol concentration for a variety of applications in the alcoholic beverage inspection and control field. PMID:23940501

  2. Convenient quantification of methanol concentration detection utilizing an integrated microfluidic chip.

    PubMed

    Wang, Yao-Nan; Yang, Ruey-Jen; Ju, Wei-Jhong; Wu, Ming-Chang; Fu, Lung-Ming

    2012-09-01

    A rapid and simple technique is proposed for methanol concentration detection using a PMMA (Polymethyl-Methacrylate) microfluidic chip patterned using a commercially available CO2 laser scriber. In the proposed device, methanol and methanol oxidase (MOX) are injected into a three-dimensional circular chamber and are mixed via a vortex stirring effect. The mixture is heated to prompt the formation of formaldehyde and is flowed into a rectangular chamber, to which fuchsin-sulphurous acid is then added. Finally, the microchip is transferred to a UV spectrophotometer for methanol detection purposes. The experimental results show that a correlation coefficient of R(2) = 0.9940 is obtained when plotting the optical density against the methanol concentration for samples and an accuracy as high as 93.1% are compared with the determined by the high quality gas chromatography with concentrations in the range of 2 ∼ 100 ppm. The methanol concentrations of four commercial red wines are successfully detected using the developed device. Overall, the results show that the proposed device provides a rapid and accurate means of detecting the methanol concentration for a variety of applications in the alcoholic beverage inspection and control field.

  3. Development of micropump-actuated negative pressure pinched injection for parallel electrophoresis on array microfluidic chip.

    PubMed

    Li, Bowei; Jiang, Lei; Xie, Hua; Gao, Yan; Qin, Jianhua; Lin, Bingcheng

    2009-09-01

    A micropump-actuated negative pressure pinched injection method is developed for parallel electrophoresis on a multi-channel LIF detection system. The system has a home-made device that could individually control 16-port solenoid valves and a high-voltage power supply. The laser beam is excitated and distributes to the array separation channels for detection. The hybrid Glass-PDMS microfluidic chip comprises two common reservoirs, four separation channels coupled to their respective pneumatic micropumps and two reference channels. Due to use of pressure as a driving force, the proposed method has no sample bias effect for separation. There is only one high-voltage supply needed for separation without relying on the number of channels, which is significant for high-throughput analysis, and the time for sample loading is shortened to 1 s. In addition, the integrated micropumps can provide the versatile interface for coupling with other function units to satisfy the complicated demands. The performance is verified by separation of DNA marker and Hepatitis B virus DNA samples. And this method is also expected to show the potential throughput for the DNA analysis in the field of disease diagnosis.

  4. On-chip characterization of cryoprotective agent mixtures using an EWOD-based digital microfluidic device

    PubMed Central

    Park, Sinwook; Wijethunga, Pavithra A. L.; Moon, Hyejin; Han, Bumsoo

    2011-01-01

    For tissue engineering and regenerative medicine, cryopreservation, a technique for preserving biomaterials in the frozen state with cryoprotective agents (CPAs), is critically important for preserving engineered tissues (ETs) as well as cells necessary to create ETs. As more diverse ETs are produced using various cell types, CPAs and corresponding freeze/thaw (F/T) protocols need to be developed cell/tissue-type specifically. This is because CPAs and F/T protocols that have been successful for one cell/tissue type have proven to be difficult to adapt to other cell/tissue types. The most critical barrier to address this challenge is the inability to screen and identify CPA or CPA mixtures efficiently. In this paper, we developed an "electro-wetting-on-dielectic" (EWOD) based digital microfluidic platform to characterize and screen CPA mixtures cell-type specifically. The feasibility of the EWOD platform was demonstrated by characterizing and optimizing a mixture of dimethlysulfoxide (DMSO) and PBS for human breast cancer cell line as model CPA mixture and cell line. The developed platform multiplexed droplets of DMSO and PBS to create an array of DMSO-PBS mixtures, and mapped the phase change diagram of the mixture. After loading cell suspensions on the platform, the mixture was further screened on-chip for toxicity and cryoproection. The results were discussed to illustrate the capabilities and limitations of the EWOD platform for cell and tissue-type specific optimization of CPA mixtures and F/T protocols. PMID:21603697

  5. The Optimization of Electrophoresis on a Glass Microfluidic Chip and its Application in Forensic Science.

    PubMed

    Han, Jun P; Sun, Jing; Wang, Le; Liu, Peng; Zhuang, Bin; Zhao, Lei; Liu, Yao; Li, Cai X

    2017-02-07

    Microfluidic chips offer significant speed, cost, and sensitivity advantages, but numerous parameters must be optimized to provide microchip electrophoresis detection. Experiments were conducted to study the factors, including sieving matrices (the concentration and type), surface modification, analysis temperature, and electric field strengths, which all impact the effectiveness of microchip electrophoresis detection of DNA samples. Our results showed that the best resolution for ssDNA was observed using 4.5% w/v (7 M urea) lab-fabricated LPA gel, dynamic wall coating of the microchannel, electrophoresis temperatures between 55 and 60°C, and electrical fields between 350 and 450 V/cm on the microchip-based capillary electrophoresis (μCE) system. One base-pair resolution could be achieved in the 19-cm-length microchannel. Furthermore, both 9947A standard genomic DNA and DNA extracted from blood spots were demonstrated to be successfully separated with well-resolved DNA peaks in 8 min. Therefore, the microchip electrophoresis system demonstrated good potential for rapid forensic DNA analysis.

  6. Microfluidics and photonics for Bio-System-on-a-Chip: a review of advancements in technology towards a microfluidic flow cytometry chip.

    PubMed

    Godin, Jessica; Chen, Chun-Hao; Cho, Sung Hwan; Qiao, Wen; Tsai, Frank; Lo, Yu-Hwa

    2008-10-01

    Microfluidics and photonics come together to form a field commonly referred to as 'optofluidics'. Flow cytometry provides the field with a technology base from which both microfluidic and photonic components be developed and integrated into a useful device. This article reviews some of the more recent developments to familiarize a reader with the current state of the technologies and also highlights the requirements of the device and how researchers are working to meet these needs.

  7. An Aluminum Microfluidic Chip Fabrication Using a Convenient Micromilling Process for Fluorescent Poly(dl-lactide-co-glycolide) Microparticle Generation

    PubMed Central

    Lin, Yung-Sheng; Yang, Chih-Hui; Wang, Chih-Yu; Chang, Fang-Rong; Huang, Keng-Shiang; Hsieh, Wan-Chen

    2012-01-01

    This study presents the development of a robust aluminum-based microfluidic chip fabricated by conventional mechanical micromachining (computer numerical control-based micro-milling process). It applied the aluminum-based microfluidic chip to form poly(lactic-co-glycolic acid) (PLGA) microparticles encapsulating CdSe/ZnS quantum dots (QDs). A cross-flow design and flow-focusing system were employed to control the oil-in-water (o/w) emulsification to ensure the generation of uniformly-sized droplets. The size of the droplets could be tuned by adjusting the flow rates of the water and oil phases. The proposed microfluidic platform is easy to fabricate, set up, organize as well as program, and is valuable for further applications under harsh reaction conditions (high temperature and/or strong organic solvent systems). The proposed method has the advantages of actively controlling the droplet diameter, with a narrow size distribution, good sphericity, as well as being a simple process with a high throughput. In addition to the fluorescent PLGA microparticles in this study, this approach can also be applied to many applications in the pharmaceutical and biomedical area. PMID:22438719

  8. Hot embossing and thermal bonding of poly(methyl methacrylate) microfluidic chips using positive temperature coefficient ceramic heater.

    PubMed

    Wang, Xia; Zhang, Luyan; Chen, Gang

    2011-11-01

    As a self-regulating heating device, positive temperature coefficient ceramic heater was employed for hot embossing and thermal bonding of poly(methyl methacrylate) microfluidic chip because it supplied constant-temperature heating without electrical control circuits. To emboss a channel plate, a piece of poly(methyl methacrylate) plate was sandwiched between a template and a microscopic glass slide on a positive temperature coefficient ceramic heater. All the assembled components were pressed between two elastic press heads of a spring-driven press while a voltage was applied to the heater for 10 min. Subsequently, the embossed poly(methyl methacrylate) plate bearing negative relief of channel networks was bonded with a piece of poly(methyl methacrylate) cover sheet to obtain a complete microchip using a positive temperature coefficient ceramic heater and a spring-driven press. High quality microfluidic chips fabricated by using the novel embossing/bonding device were successfully applied in the electrophoretic separation of three cations. Positive temperature coefficient ceramic heater indicates great promise for the low-cost production of poly(methyl methacrylate) microchips and should find wide applications in the fabrication of other thermoplastic polymer microfluidic devices.

  9. A controlled microfluidic electrochemical lab-on-a-chip for label-free diffusion-restricted DNA hybridization analysis.

    PubMed

    Ben-Yoav, Hadar; Dykstra, Peter H; Bentley, William E; Ghodssi, Reza

    2015-02-15

    Lab-on-a-chip (LOC) devices for electrochemical analysis of DNA hybridization events offer a technology for real-time and label-free assessment of biomarkers at the point-of-care. Here, we present a microfluidic LOC, with 3 × 3 arrayed electrochemical sensors for the analysis of DNA hybridization events. A new dual layer microfluidic valved manipulation system is integrated providing controlled and automated capabilities for high throughput analysis. This feature improves the repeatability, accuracy, and overall sensing performance (Fig. 1). The electrochemical activity of the fabricated microfluidic device is validated and demonstrated repeatable and reversible Nernstian characteristics. System design required detailed analysis of energy storage and dissipation as our sensing modeling involves diffusion-related electrochemical impedance spectroscopy. The effect of DNA hybridization on the calculated charge transfer resistance and the diffusional resistance components is evaluated. We demonstrate a specific device with an average cross-reactivity value of 27.5%. The device yields semilogarithmic dose response and enables a theoretical detection limit of 1 nM of complementary ssDNA target. This limit is lower than our previously reported non-valved device by 74% due to on-chip valve integration providing controlled and accurate assay capabilities.

  10. Microfluidic system for on-chip high-throughput whole-animal sorting and screening at subcellular resolution

    PubMed Central

    Rohde, Christopher B.; Zeng, Fei; Gonzalez-Rubio, Ricardo; Angel, Matthew; Yanik, Mehmet Fatih

    2007-01-01

    We report a suite of key microfluidic devices for complex high-throughput whole-animal genetic and drug screens. We demonstrate a high-speed microfluidic sorter that can isolate and immobilize Caenorhabditis elegans in a well defined geometry for screening phenotypic features at subcellular resolution in physiologically active animals. We show an integrated chip containing individually addressable screening-chamber devices for incubation and exposure of individual animals to biochemical compounds and high-resolution time-lapse imaging of many animals on a single chip without the need for anesthesia. We describe a design for delivery of compound libraries in standard multiwell plates to microfluidic devices and also for rapid dispensing of screened animals into multiwell plates. When used in various combinations, these devices will facilitate a variety of high-throughput assays using whole animals, including mutagenesis and RNAi and drug screens at subcellular resolution, as well as high-throughput high-precision manipulations such as femtosecond laser microsurgery for large-scale in vivo neural degeneration and regeneration studies. PMID:17715055

  11. Epithelial cell adhesion molecule independent capture of non-small lung carcinoma cells with peptide modified microfluidic chip.

    PubMed

    Pu, Kefeng; Li, Chunlin; Zhang, Nengpan; Wang, Hui; Shen, Wenjiang; Zhu, Yimin

    2017-03-15

    Circulating tumor cells (CTCs) present in the blood of patients with non-hematological cancers are accessible sources for diagnosis and monitoring of cancers. By the aid of the ability of the anti-EpCAM antibody to recognize the epithelial cells, microsystem-based technologies provide robust means for effectively detecting CTCs in vitro. Considering the EpCAM expression is down-regulated during epithelial-mesenchymal transition (EMT) process, the amount of CTCs detected based on anti-EpCAM antibody is underestimated. In our study, the A549 cells targeting peptide (A-1 peptide), as the substitute of anti-EpCAM antibody, was introduced to microfluidic chip to capture A549 cells. Our results showed that both epithelial-like and mesenchymal-like A549 cells could efficiently be captured by the A-1 peptide modified microfluidic chip, and the capture efficiency for epithelial-like cells is comparable to that captured by the EpCAM antibody. Thus, we concluded that the peptide could be a better supplement to the EpCAM antibody for capturing CTCs in microfluidic system with broader spectrum.

  12. Bioprinting cell-laden matrigel for radioprotection study of liver by pro-drug conversion in a dual-tissue microfluidic chip.

    PubMed

    Snyder, J E; Hamid, Q; Wang, C; Chang, R; Emami, K; Wu, H; Sun, W

    2011-09-01

    The objective of this paper is to introduce a novel cell printing and microfluidic system to serve as a portable ground model for the study of drug conversion and radiation protection of living liver tissue analogs. The system is applied to study behavior in ground models of space stress, particularly radiation. A microfluidic environment is engineered by two cell types to prepare an improved higher fidelity in vitro micro-liver tissue analog. Cell-laden Matrigel printing and microfluidic chips were used to test radiation shielding to liver cells by the pro-drug amifostine. In this work, the sealed microfluidic chip regulates three variables of interest: radiation exposure, anti-radiation drug treatment and single- or dual-tissue culture environments. This application is intended to obtain a scientific understanding of the response of the multi-cellular biological system for long-term manned space exploration, disease models and biosensors.

  13. Integration of gold nanoparticles in PDMS microfluidics for lab-on-a-chip plasmonic biosensing of growth hormones.

    PubMed

    SadAbadi, Hamid; Badilescu, Simona; Packirisamy, Muthukumaran; Wüthrich, Rolf

    2013-06-15

    Gold nanoparticles were synthesized in a poly(dimethylsiloxane) (PDMS) microfluidic chip by using an in-situ method, on the basis of reductive properties of the cross-linking agent of PDMS. The proposed integrated device was further used as a sensitive and low-cost LSPR-based biosensor for the detection of polypeptides. Synthesis of nanoparticles in the microfluidic environment resulted in improvement of size distribution with only 8% variation, compared with the macro-environment that yields about 67% variation in size. The chemical kinetics of the in-situ reaction in the microfluidic environment was studied in detail and compared with the reaction carried out at the macro-scale. The effect of temperature and gold precursor concentration on the kinetics of the reaction was investigated and the apparent activation energy was estimated to be Ea*=30 kJ/mol. The sensitivity test revealed that the proposed sensor has a high sensitivity of 74 nm/RIU to the surrounding medium. The sensing of bovine growth hormone also known as bovine somatotropin (bST) shows that the proposed biosensor can reach a detection limit of as low as 3.7 ng/ml (185 pM). The results demonstrate the successful integration of microfluidics and nanoparticles which provides a potential alternative for protein detection in clinical diagnostics. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Rapid and reproducible analysis of thiocyanate in real human serum and saliva using a droplet SERS-microfluidic chip.

    PubMed

    Wu, Lei; Wang, Zhuyuan; Zong, Shenfei; Cui, Yiping

    2014-12-15

    As thiocyanate (SCN(-)) acts as an important biomarker in human health assessment, there remains an urgent need to realize rapid and reproducible analysis of SCN(-) in body fluids. Here, a droplet microfluidic device has been designed and fabricated for SCN(-) detection in real human serum and saliva using the surface enhanced Raman scattering (SERS) technique. Only a few minutes are needed for the whole detection process which simply cost a few microliters of real sample. Gold@silver core-shell nanorods (Au@Ag NRs) with a large SERS enhancement factor were selected to capture SCN(-) ions in body fluids. The intensity of SERS peak at around 2100 cm(-1), which originates from the -C≡N stretching mode, was used to indicate the concentrations of SCN(-) ions. Importantly, by generating a droplet environment for mixing reagents and acquiring signals, this microfluidic platform possesses the advantages of an improved reproducibility and reduced time consumption. For practical applications, the SERS-microfluidic system is capable to achieve rapid analysis of SCN(-) in the presence of human serum, which is very important for realizing the detection in real biological samples. Additionally, SCN(-) in saliva samples was detected in the SERS-microfluidic chip and the results provide useful information for distinguishing between smokers and nonsmokers. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Microfluidics meets thin-film electronics: a new approach towards an integrated intelligent lab-on-a-chip

    NASA Astrophysics Data System (ADS)

    Schafer, Heiko; Chemnitz, Steffen; Schumacher, Stephanie; Koziy, Volodymyr; Fischer, Alexander; Meixner, Alfred J.; Ehrhardt, Dietmar; Bohm, Markus

    2003-04-01

    A novel architecture for a lab-on-a-chip is presented. The architecture consists of a microfluidic system including integrated optical sensors and thin film transistors. The concept is based on the TFA (Thin Film on ASIC) technology that was developed at University of Siegen. The device consists of two substrate plates that are sandwiched together using oxygen plasma bonding. The thicker bottom plate contains the contacts to the microfluidic channels, while the thinner top plate contains the microfluidic system. The top plate is bonded face down onto the bottom substrate, and, on its reverse side, hydrogenated amorphous silicon (a-Si:H) based pin-diodes and thin film transistors (TFTs) are deposited for optical detection and data transfer. The pin-diodes and the TFTs are manufactured by PECVD (Plasma Enhanced Chemical Vapor Deposition) from silane, ammonia and dopant gases at temperatures around 200°C. Sputtered ZnO:Al is used as semitransparent front contact for the diodes, while Al and Cr are used as contacts to the transistors. The TFTs are used as switches to read out an array of pin-diodes. Experimental results for an electrokinetic microfluidic pump and the a-Si:H devices are reported. Further developments and potential applications for microanalysis are outlined.

  16. Flow control using audio tones in resonant microfluidic networks: towards cell-phone controlled lab-on-a-chip devices.

    PubMed

    Phillips, Reid H; Jain, Rahil; Browning, Yoni; Shah, Rachana; Kauffman, Peter; Dinh, Doan; Lutz, Barry R

    2016-08-16

    Fluid control remains a challenge in development of portable lab-on-a-chip devices. Here, we show that microfluidic networks driven by single-frequency audio tones create resonant oscillating flow that is predicted by equivalent electrical circuit models. We fabricated microfluidic devices with fluidic resistors (R), inductors (L), and capacitors (C) to create RLC networks with band-pass resonance in the audible frequency range available on portable audio devices. Microfluidic devices were fabricated from laser-cut adhesive plastic, and a "buzzer" was glued to a diaphragm (capacitor) to integrate the actuator on the device. The AC flowrate magnitude was measured by imaging oscillation of bead tracers to allow direct comparison to the RLC circuit model across the frequency range. We present a systematic build-up from single-channel systems to multi-channel (3-channel) networks, and show that RLC circuit models predict complex frequency-dependent interactions within multi-channel networks. Finally, we show that adding flow rectifying valves to the network creates pumps that can be driven by amplified and non-amplified audio tones from common audio devices (iPod and iPhone). This work shows that RLC circuit models predict resonant flow responses in multi-channel fluidic networks as a step towards microfluidic devices controlled by audio tones.

  17. Selecting and designing with the right thermoplastic polymer for your microfluidic chip: a close look into cyclo-olefin polymer

    NASA Astrophysics Data System (ADS)

    Nevitt, Mark

    2013-03-01

    Engineers who are developing microfluidic devices and bioMEMs for life science applications have many aspects to consider when selecting the proper base materials for constructing a device. While glass and polydimethylsiloxane (PDMS) are the staple materials for proof-of-concept and prototype chip fabrication, they are not a feasible solution for commercial production due to their slow, labor-intensive production rate. Alternatively, a molded or extruded thermoplastic solution can deliver the precision, consistency, and high volume capability required for commercial scale production. Traditional thermoplastics, such as polymethylmethacrylate (PMMA), polycarbonate (PC), and polystyrene (PS), are well known by development engineers in the bioscience community; however, cyclo-olefin polymer (COP), a relative newcomer in the world of plastics, is gaining increasing attention for use in microfluidic devices due to its unique balance of key properties compared to conventional thermoplastics. In this paper, we provide a comprehensive look at the properties which make COP an excellent candidate for providing the flow cell support and reagent storage functions in microfluidic assays. We also explore the processing attributes and capabilities of COP resin and film which are crucial for manufacturing high-performance microfluidic devices.

  18. Dopamine-functionalized InP/ZnS quantum dots as fluorescence probes for the detection of adenosine in microfluidic chip

    PubMed Central

    Ankireddy, Seshadri Reddy; Kim, Jongsung

    2015-01-01

    Microbeads are frequently used as solid supports for biomolecules such as proteins and nucleic acids in heterogeneous microfluidic assays. Chip-based, quantum dot (QD)-bead-biomolecule probes have been used for the detection of various types of DNA. In this study, we developed dopamine (DA)-functionalized InP/ZnS QDs (QDs-DA) as fluorescence probes for the detection of adenosine in microfluidic chips. The photoluminescence (PL) intensity of the QDs-DA is quenched by Zn2+ because of the strong coordination interactions. In the presence of adenosine, Zn2+ cations preferentially bind to adenosine, and the PL intensity of the QDs-DA is recovered. A polydimethylsiloxane-based microfluidic chip was fabricated, and adenosine detection was confirmed using QDs-DA probes. PMID:26347351

  19. A β-Camera Integrated with a Microfluidic Chip for Radioassays Based on Real-Time Imaging of Glycolysis in Small Cell Populations

    PubMed Central

    Vu, Nam T.; Yu, Zeta T.F.; Comin-Anduix, Begonya; Søndergaard, Jonas N.; Silverman, Robert W.; Chang, Canny Y.N.; Ribas, Antoni; Tseng, Hsian-Rong; Chatziioannou, Arion F.

    2012-01-01

    An integrated β-camera and microfluidic chip was developed that is capable of quantitative imaging of glycolysis radioassays using 18F-FDG in small cell populations down to a single cell. This paper demonstrates that the integrated system enables digital control and quantitative measurements of glycolysis in B-RafV600E–mutated melanoma cell lines in response to specific B-Raf inhibition. Methods The β-camera uses a position-sensitive avalanche photodiode to detect charged particle–emitting probes within a microfluidic chip. The integrated β-camera and microfluidic chip system was calibrated, and the linearity was measured using 4 different melanoma cell lines (M257, M202, M233, and M229). Microfluidic radioassays were performed with cell populations ranging from hundreds of cells down to a single cell. The M229 cell line has a homozygous B-RafV600E mutation and is highly sensitive to a B-Raf inhibitor, PLX4032. A microfluidic radioassay was performed over the course of 3 days to assess the cytotoxicity of PLX4032 on cellular 18F-FDG uptake. Results The β-camera is capable of imaging radioactive uptake of 18F-FDG in microfluidic chips. 18F-FDG uptake for a single cell was measured using a radioactivity concentration of 37 MBq/mL during the radiotracer incubation period. For in vitro cytotoxicity monitoring, the β-camera showed that exposure to 1 µM PLX4032 for 3 days decreased the 18F-FDG uptake per cell in highly sensitive M229 cells, compared with vehicle controls. Conclusion The integrated β-camera and microfluidic chip can provide digital control of live cell cultures and allow in vitro quantitative radioassays for multiple samples simultaneously. PMID:21536929

  20. Microfluidic Lab-on-a-Chip Platforms: Requirements, Characteristics and Applications

    NASA Astrophysics Data System (ADS)

    Mark, D.; Haeberle, S.; Roth, G.; Von Stetten, F.; Zengerle, R.

    This review summarizes recent developments in microfluidic platform approaches. In contrast to isolated application-specific solutions, a microfluidic platform provides a set of fluidic unit operations, which are designed for easy combination within a well-defined fabrication technology. This allows the implementation of different application-specific (bio-) chemical processes, automated by microfluidic process integration [1]. A brief introduction into technical advances, major market segments and promising applications is followed by a detailed characterization of different microfluidic platforms, comprising a short definition, the functional principle, microfluidic unit operations, application examples as well as strengths and limitations. The microfluidic platforms in focus are lateral flow tests, linear actuated devices, pressure driven laminar flow, microfluidic large scale integration, segmented flow microfluidics, centrifugal microfluidics, electro-kinetics, electrowetting, surface acoustic waves, and systems for massively parallel analysis. The review concludes with the attempt to provide a selection scheme for microfluidic platforms which is based on their characteristics according to key requirements of different applications and market segments. Applied selection criteria comprise portability, costs of instrument and disposable, sample throughput, number of parameters per sample, reagent consumption, precision, diversity of microfluidic unit operations and the flexibility in programming different liquid handling protocols.

  1. Real-time electrical impedimetric monitoring of blood coagulation process under temperature and hematocrit variations conducted in a microfluidic chip.

    PubMed

    Lei, Kin Fong; Chen, Kuan-Hao; Tsui, Po-Hsiang; Tsang, Ngan-Ming

    2013-01-01

    Blood coagulation is an extremely complicated and dynamic physiological process. Monitoring of blood coagulation is essential to predict the risk of hemorrhage and thrombosis during cardiac surgical procedures. In this study, a high throughput microfluidic chip has been developed for the investigation of the blood coagulation process under temperature and hematocrit variations. Electrical impedance of the whole blood was continuously recorded by on-chip electrodes in contact with the blood sample during coagulation. Analysis of the impedance change of the blood was conducted to investigate the characteristics of blood coagulation process and the starting time of blood coagulation was defined. The study of blood coagulation time under temperature and hematocrit variations was shown a good agreement with results in the previous clinical reports. The electrical impedance measurement for the definition of blood coagulation process provides a fast and easy measurement technique. The microfluidic chip was shown to be a sensitive and promising device for monitoring blood coagulation process even in a variety of conditions. It is found valuable for the development of point-of-care coagulation testing devices that utilizes whole blood sample in microliter quantity.

  2. Rhipsalis (Cactaceae)-like Hierarchical Structure Based Microfluidic Chip for Highly Efficient Isolation of Rare Cancer Cells.

    PubMed

    Yan, Shuangqian; Zhang, Xian; Dai, Xiaofang; Feng, Xiaojun; Du, Wei; Liu, Bi-Feng

    2016-12-14

    The circulating tumor cells (CTCs), originating from the primary tumor, play a vital role in cancer diagnosis, prognosis, disease monitoring, and precise therapy. However, the CTCs are extremely rare in the peripheral bloodstream and hard to be isolated. To overcome current limitations associated with CTC capture and analysis, the strategy incorporating nanostructures with microfluidic devices receives wide attention. Here, we demonstrated a three-dimensional microfluidic device (Rm-chip) for capturing cancer cells with high efficiency by integrating a novel hierarchical structure, the "Rhipsalis (Cactaceae)"-like micropillar array, into the Rm-chip. The PDMS micropillar array was fabricated by soft-lithography and rapid prototyping method, which was then conformally plated with a thin gold layer through electroless plating. EpCAM antibody was modified onto the surface of the micropillars through the thiol-oligonucleotide linkers in order to release captured cancer cells by DNase I treatment. The antibody-functionalized device achieved an average capture efficiency of 88% in PBS and 83.7% in whole blood samples. We believe the Rm-chip provided a convenient, economical, and versatile approach for cell analysis with wide potential applications.

  3. Real-Time Electrical Impedimetric Monitoring of Blood Coagulation Process under Temperature and Hematocrit Variations Conducted in a Microfluidic Chip

    PubMed Central

    Lei, Kin Fong; Chen, Kuan-Hao; Tsui, Po-Hsiang; Tsang, Ngan-Ming

    2013-01-01

    Blood coagulation is an extremely complicated and dynamic physiological process. Monitoring of blood coagulation is essential to predict the risk of hemorrhage and thrombosis during cardiac surgical procedures. In this study, a high throughput microfluidic chip has been developed for the investigation of the blood coagulation process under temperature and hematocrit variations. Electrical impedance of the whole blood was continuously recorded by on-chip electrodes in contact with the blood sample during coagulation. Analysis of the impedance change of the blood was conducted to investigate the characteristics of blood coagulation process and the starting time of blood coagulation was defined. The study of blood coagulation time under temperature and hematocrit variations was shown a good agreement with results in the previous clinical reports. The electrical impedance measurement for the definition of blood coagulation process provides a fast and easy measurement technique. The microfluidic chip was shown to be a sensitive and promising device for monitoring blood coagulation process even in a variety of conditions. It is found valuable for the development of point-of-care coagulation testing devices that utilizes whole blood sample in microliter quantity. PMID:24116099

  4. Fabrication of high-aspect-ratio microstructures in polymer microfluid chips for in vitro single-cell analysis

    NASA Astrophysics Data System (ADS)

    Bukatin, A. S.; Mukhin, I. S.; Malyshev, E. I.; Kukhtevich, I. V.; Evstrapov, A. A.; Dubina, M. V.

    2016-10-01

    Technologies and methods of prototyping microfluidic devices are widely used in solving many biological problems and testing of operability of new microanalytic systems. This study is devoted to analyzing the features of the formation of microstructures in SU-8 photoresist and the preparation of replicas in polydimethyl siloxane by the soft lithography method. It has been shown that the aspect ratio of the resultant microstructures is determined by their shape, size, and the force of resist adhesion to the silicon substrate and the efficiency of the circulation of the developer around microstructures. In the replication of complex microstructures, an aspect ratio of 25 is attained. The technology considered here is used to prepare microfluidic chips with mechanical traps for fixation and the in vitro analysis of living cells.

  5. Imaging new transient nanostructures using a microfluidic chip integrated with a controlled environment vitrification system for cryogenic transmission electron microscopy.

    PubMed

    Lee, Jinkee; Jha, Ashish K; Bose, Arijit; Tripathi, Anubhav

    2008-11-18

    Nanostructures (vesicles, micelles, bilayers) are important in nanomedicine and biochemical processes. They are agents for encapsulation and eventual release of drugs, flavors, and fragrances. The structural transition from micelles to vesicles through disk-like intermediate states has been demonstrated previously. Here, we disclose a new route for the micelle-vesicle transition, where micelles aggregate to first form long tubules that become unstable, and break up into vesicles. A simple theory, based on energy principles, is presented to explain the tubule-vesicle transition. Observation of this new tubular intermediate state has been facilitated by the development of an integrated microfluidic chip/cryogenic transmission electron microscopy (cryo-TEM) unit. Although this transition has been observed in a specific amphiphilic system where micellar solutions of cetyltrimethylammonium bromide (CTAB) and dodecylbenzene sulfonic acid (HDBS) are mixed to form vesicles, this new tool can be applied broadly to study transient structures in nanoscale systems under the very controlled conditions provided by microfluidics.

  6. Separation of carboxylic acids in human serum by isotachophoresis using a commercial field-deployable analytical platform combined with in-house glass microfluidic chips.

    PubMed

    Smejkal, Petr; Breadmore, Michael C; Guijt, Rosanne M; Grym, Jakub; Foret, František; Bek, Fritz; Macka, Mirek

    2012-11-28

    Portable and field deployable analytical instruments are attractive in many fields including medical diagnostics, where point of care and on-site diagnostics systems capable of providing rapid quantitative results have the potential to vastly improve the productivity and the quality of medical care. Isotachophoresis (ITP) is a well known electrophoretic separation technique previously demonstrated as suitable for miniaturization in microfluidic chip format (chip-ITP). In this work, a purpose-designed ITP chip compatible with a commercial end-used targeted microfluidic system was used to study different injection protocols and to evaluate the effect of the length of the separation channel on the analytical performance. The in-house ITP chips were made from Corning glass and compared to the commercial DNA chip for the ITP separation of anions from the hydrodynamic injection of human serum. Using the in-house ITP chip the isotachophoretic step of lactate from human serum was approximately two times longer. The results of this research suggested that microfluidic ITP with indirect fluorescence detection is a viable technique for separation of organic acids in human serum samples, especially when a chip with suitable design is used.

  7. Study of endothelial cell apoptosis using fluorescence resonance energy transfer (FRET) biosensor cell line with hemodynamic microfluidic chip system.

    PubMed

    Yu, J Q; Liu, X F; Chin, L K; Liu, A Q; Luo, K Q

    2013-07-21

    To better understand how hyperglycemia induces endothelial cell dysfunction under the diabetic conditions, a hemodynamic microfluidic chip system was developed. The system combines a caspase-3-based fluorescence resonance energy transfer (FRET) biosensor cell line which can detect endothelial cell apoptosis in real-time, post-treatment effect and with a limited cell sample, by using a microfluidic chip which can mimic the physiological pulsatile flow profile in the blood vessel. The caspase-3-based FRET biosensor endothelial cell line (HUVEC-C3) can produce a FRET-based sensor protein capable of probing caspase-3 activation. When the endothelial cells undergo apoptosis, the color of the sensor cells changes from green to blue, thus sensing apoptosis. A double-labeling fluorescent technique (yo pro-1 and propidium iodide) was used to validate the findings revealed by the FRET-based caspase sensor. The results show high rates of apoptosis and necrosis of endothelial cells when high glucose concentration was applied in our hemodynamic microfluidic chip combined with an exhaustive pulsatile flow profile. The two apoptosis detection techniques (fluorescent method and FRET biosensor) are comparable; but FRET biosensor offers more advantages such as real-time observation and a convenient operating process to generate more accurate and reliable data. Furthermore, the activation of the FRET biosensor also confirms the endothelial cell apoptosis induced by the abnormal pulsatile shear stress and high glucose concentration is through caspase-3 pathway. A 12% apoptotic rate (nearly a 4-fold increase compared to the static condition) was observed when the endothelial cells were exposed to a high glucose concentration of 20 mM under 2 h exhaustive pulsatile shear stress of 30 dyne cm(-2) and followed with another 10 h normal pulsatile shear stress of 15 dyne cm(-2). Therefore, the most important finding of this study is to develop a novel endothelial cell apoptosis detection

  8. High-volume production of single and compound emulsions in a microfluidic parallelization arrangement coupled with coaxial annular world-to-chip interfaces.

    PubMed

    Nisisako, Takasi; Ando, Takuya; Hatsuzawa, Takeshi

    2012-09-21

    This study describes a microfluidic platform with coaxial annular world-to-chip interfaces for high-throughput production of single and compound emulsion droplets, having controlled sizes and internal compositions. The production module consists of two distinct elements: a planar square chip on which many copies of a microfluidic droplet generator (MFDG) are arranged circularly, and a cubic supporting module with coaxial annular channels for supplying fluids evenly to the inlets of the mounted chip, assembled from blocks with cylinders and holes. Three-dimensional flow was simulated to evaluate the distribution of flow velocity in the coaxial multiple annular channels. By coupling a 1.5 cm × 1.5 cm microfluidic chip with parallelized 144 MFDGs and a supporting module with two annular channels, for example, we could produce simple oil-in-water (O/W) emulsion droplets having a mean diameter of 90.7 μm and a coefficient of variation (CV) of 2.2% at a throughput of 180.0 mL h(-1). Furthermore, we successfully demonstrated high-throughput production of Janus droplets, double emulsions and triple emulsions, by coupling 1.5 cm × 1.5 cm - 4.5 cm × 4.5 cm microfluidic chips with parallelized 32-128 MFDGs of various geometries and supporting modules with 3-4 annular channels.

  9. Active metamaterial: Gain and stability, and microfluidic chip for THz cell spectroscopy

    NASA Astrophysics Data System (ADS)

    Tang, Qi

    . THz spectroscopy becomes an emerging technique for studying the dynamics and interactions of cells and biomolecules, but many practical challenges still remain in experimental studies. We present a prototype of simple and inexpensive cell-trapping microfluidic chip for THz spectroscopic study of live cells. Cells are transported, trapped and concentrated into the THz exposure region by applying an AC bias signal while the chip maintains a steady temperature at 37 ?C by resistive heating. We conduct some preliminary experiments on E. coli and T cell solution and compare the transmission spectra of empty channels, channels filled with aqueous media only, and channels filled with aqueous medium with un-concentrated and concentrated cells.

  10. Automation of daphtoxkit-F biotest using a microfluidic lab-on-a-chip technology

    NASA Astrophysics Data System (ADS)

    Huang, Yushi; Nugegoda, Dayanthi; Wlodkowic, Donald

    2015-12-01

    An increased rigor in water quality monitoring is not only a legal requirement, but is also critical to ensure timely chemical hazard emergency responses and protection of human and animal health. Bioindication is a method that applies very sensitive living organisms to detect environmental changes using their natural responses. Although bioindicators do not deliver information on an exact type or intensity of toxicants present in water samples, they do provide an overall snapshot and early-warning information about presence of harmful and dangerous parameters. Despite the advantages of biotests performed on sentinel organisms, their wider application is limited by the nonexistence of high-throughput laboratory automation systems. As a result majority of biotests used in ecotoxicology require time-consuming and laborious manual procedures. In this work, we present development of a miniaturized Lab-on-a-Chip (LOC) platform for automation and enhancement of acute ecotoxicity test based on immobilization of a freshwater crustacean Daphnia magna (Daphtoxkit-FTM). Daphnids' immobilization in response to sudden changes in environment parameters is fast, unambiguous, and easy to record optically. We also for the first time demonstrate that LOC system enables studies of sub-lethal ecotoxic effects using behavioral responses of Daphnia magna as sentinels of water pollution. The system working principle incorporated a high definition (HD) time-resolved video data analysis to dynamically assess impact of the reference toxicant on swimming behavior of D. magna. Our system design combined: (i) microfluidic device for caging of Daphnia sp.; (ii) mechatronic interface for fluidic actuation; (iii) video data acquisition; and (iv) algorithms for animal movement tracking and analysis.

  11. A large format membrane-based x-ray mask for microfluidic chip fabrication

    NASA Astrophysics Data System (ADS)

    Wang, Lin; Zhang, Min; Desta, Yohannes; Melzak, J.; Wu, C. H.; Peng, Zhengchun

    2006-02-01

    X-ray lithography is a very good option for the fabrication of micro-devices especially when high aspect ratio patterns are required. Membrane-based x-ray masks are commonly used for high-resolution x-ray lithography. A thin layer of silicon nitride (Si3N4) or silicon carbide (SiC) film (1-2 µm) is normally used as the membrane material for x-ray mask fabrication (Wells G M, Reilly M, Nachman R, Cerrina F, El-Khakani M A and Chaker M 1993 Mater. Res. Soc. Conf. Proc. 306 81-9 Shoki T, Nagasawa H, Kosuga H, Yamaguchi Y, Annaka N, Amemiya I and Nagarekawa O 1993 SPIE Proc. 1924 450-6). The freestanding membrane window of an x-ray mask, which defines the exposing area of the x-ray mask, can be obtained by etching a pre-defined area on a silicon wafer from the backside (Wang L, Desta Y, Fettig R K, Goettert J, Hein H, Jakobs P and Chulz J 2004 J. Micromech. Microeng. 14 722-6). Usually, the window size of an x-ray mask is around 20 × 20 mm because of the low tensile stress of the membrane (10-100 MPa), and the larger window dimension of an x-ray mask may cause the deformation of membranes and lower the mask quality. However, x-ray masks with larger windows are preferred for micro-device fabrication in order to increase the productivity. We analyzed the factors which influence the flatness of large format x-ray masks and fabricated x-ray masks with a window size of 55 × 55 mm and 46 × 65 mm on 1 µm thick membranes by increasing the tensile stress of the membranes (>300 MPa) and optimizing the stress of the absorber layer. The large format x-ray mask was successfully applied for the fabrication of microfluidic chips.

  12. Flow-orthogonal bead oscillation in a microfluidic chip with a magnetic anisotropic flux-guide array.

    PubMed

    van Pelt, Stijn; Derks, Roy; Matteucci, Marco; Hansen, Mikkel Fougt; Dietzel, Andreas

    2011-04-01

    A new concept for the manipulation of superparamagnetic beads inside a microfluidic chip is presented in this paper. The concept allows for bead actuation orthogonal to the flow direction inside a microchannel. Basic manipulation functionalities were studied by means of finite element simulations and results were oval-shaped steady state oscillations with bead velocities up to 500 μm/s. The width of the trajectory could be controlled by prescribing external field rotation. Successful verification experiments were performed on a prototype chip fabricated with excimer laser ablation in polycarbonate and electroforming of nickel flux-guides. Bead velocities up to 450 μm/s were measured in a 75 μm wide channel. By prescribing the currents in the external quadrupole magnet, the shape of the bead trajectory could be controlled.

  13. StyletChip: a microfluidic device for recording host invasion behaviour and feeding of plant parasitic nematodes.

    PubMed

    Hu, Chunxiao; Kearn, James; Urwin, Peter; Lilley, Catherine; O' Connor, Vincent; Holden-Dye, Lindy; Morgan, Hywel

    2014-07-21

    Plant parasitic nematodes (PPNs) infest the roots of crops and cause global losses with a severe economic impact on food production. Current chemical control agents are being removed from use due to environmental and toxicity concerns and there is a need for new approaches to crop protection. A key feature of parasitic behaviour for the majority of PPNs is a hollow stomastyle or odontostyle required for interaction with the host plant and feeding. This lance-like microscopic structure, often called a stylet, protrudes from the mouth of the worm and thrusts in a rhythmic manner to stab the host root. Studying stylet activity presents technical challenges and as a consequence the underlying biology is poorly understood. We have addressed this by designing a microfluidic chip which traps the PPN Globodera pallida and permits the recording of an electrophysiological signal concomitant with stylet thrusting. The PDMS chip incorporates a precisely designed aperture to trap the nematode securely around a mid-point of its body. It is fabricated using a novel combination of conventional photolithography and two photon polymerization. The chip incorporates valves for rapid application of test compounds and integral electrodes to facilitate acquisition of electrical signals. We show that stylet thrusting can be induced by controlled application of 5-HT (serotonin) to the worm. Each thrust and retraction produces an electrical waveform that characterises the physiological activity associated with the worm's behaviour. The ability to reproducibly record the stylet activity of PPNs provides a new platform for nematicide screening that specifically focuses on a behaviour that is integral to the parasite host interaction. This is the first report of a microfluidic chip capable of electrophysiological recording from nematodes other than Caenorhabditis elegans. The unique approach is optimised for trapping and recording from smaller worms or worms with distinct anterior body shapes

  14. Microfluidic Chip-Based Detection and Intraspecies Strain Discrimination of Salmonella Serovars Derived from Whole Blood of Septic Mice

    PubMed Central

    Patterson, Adriana S.; Heithoff, Douglas M.; Ferguson, Brian S.; Soh, H. Tom; Mahan, Michael J.

    2013-01-01

    Salmonella is a zoonotic pathogen that poses a considerable public health and economic burden in the United States and worldwide. Resultant human diseases range from enterocolitis to bacteremia to sepsis and are acutely dependent on the particular serovar of Salmonella enterica subsp. enterica, which comprises over 99% of human-pathogenic S. enterica isolates. Point-of-care methods for detection and strain discrimination of Salmonella serovars would thus have considerable benefit to medical, veterinary, and field applications that safeguard public health and reduce industry-associated losses. Here we describe a single, disposable microfluidic chip that supports isothermal amplification and sequence-specific detection and discrimination of Salmonella serovars derived from whole blood of septic mice. The integrated microfluidic electrochemical DNA (IMED) chip consists of an amplification chamber that supports loop-mediated isothermal amplification (LAMP), a rapid, single-temperature amplification method as an alternative to PCR that offers advantages in terms of sensitivity, reaction speed, and amplicon yield. The amplification chamber is connected via a microchannel to a detection chamber containing a reagentless, multiplexed (here biplex) sensing array for sequence-specific electrochemical DNA (E-DNA) detection of the LAMP products. Validation of the IMED device was assessed by the detection and discrimination of S. enterica subsp. enterica serovars Typhimurium and Choleraesuis, the causative agents of enterocolitis and sepsis in humans, respectively. IMED chips conferred rapid (under 2 h) detection and discrimination of these strains at clinically relevant levels (<1,000 CFU/ml) from whole, unprocessed blood collected from septic animals. The IMED-based chip assay shows considerable promise as a rapid, inexpensive, and portable point-of-care diagnostic platform for the detection and strain-specific discrimination of microbial pathogens. PMID:23354710

  15. A 3D microfluidic chip for electrochemical detection of hydrolysed nucleic bases by a modified glassy carbon electrode.

    PubMed

    Vlachova, Jana; Tmejova, Katerina; Kopel, Pavel; Korabik, Maria; Zitka, Jan; Hynek, David; Kynicky, Jindrich; Adam, Vojtech; Kizek, Rene

    2015-01-22

    Modification of carbon materials, especially graphene-based materials, has wide applications in electrochemical detection such as electrochemical lab-on-chip devices. A glassy carbon electrode (GCE) modified with chemically alternated graphene oxide was used as a working electrode (glassy carbon modified by graphene oxide with sulphur containing compounds and Nafion) for detection of nucleobases in hydrolysed samples (HCl pH = 2.9, 100 °C, 1 h, neutralization by NaOH). It was found out that modification, especially with trithiocyanuric acid, increased the sensitivity of detection in comparison with pure GCE. All processes were finally implemented in a microfluidic chip formed with a 3D printer by fused deposition modelling technology. As a material for chip fabrication, acrylonitrile butadiene styrene was chosen because of its mechanical and chemical stability. The chip contained the one chamber for the hydrolysis of the nucleic acid and another for the electrochemical detection by the modified GCE. This chamber was fabricated to allow for replacement of the GCE.

  16. A 3D Microfluidic Chip for Electrochemical Detection of Hydrolysed Nucleic Bases by a Modified Glassy Carbon Electrode

    PubMed Central

    Vlachova, Jana; Tmejova, Katerina; Kopel, Pavel; Korabik, Maria; Zitka, Jan; Hynek, David; Kynicky, Jindrich; Adam, Vojtech; Kizek, Rene

    2015-01-01

    Modification of carbon materials, especially graphene-based materials, has wide applications in electrochemical detection such as electrochemical lab-on-chip devices. A glassy carbon electrode (GCE) modified with chemically alternated graphene oxide was used as a working electrode (glassy carbon modified by graphene oxide with sulphur containing compounds and Nafion) for detection of nucleobases in hydrolysed samples (HCl pH = 2.9, 100 °C, 1 h, neutralization by NaOH). It was found out that modification, especially with trithiocyanuric acid, increased the sensitivity of detection in comparison with pure GCE. All processes were finally implemented in a microfluidic chip formed with a 3D printer by fused deposition modelling technology. As a material for chip fabrication, acrylonitrile butadiene styrene was chosen because of its mechanical and chemical stability. The chip contained the one chamber for the hydrolysis of the nucleic acid and another for the electrochemical detection by the modified GCE. This chamber was fabricated to allow for replacement of the GCE. PMID:25621613

  17. A microfluidic chip integrating DNA extraction and real-time PCR for the detection of bacteria in saliva.

    PubMed

    Oblath, Emily A; Henley, W Hampton; Alarie, Jean Pierre; Ramsey, J Michael

    2013-04-07

    A microfluidic chip integrating DNA extraction, amplification, and detection for the identification of bacteria in saliva is described. The chip design integrated a monolithic aluminum oxide membrane (AOM) for DNA extraction with seven parallel reaction wells for real-time polymerase chain reaction (rtPCR) amplification of the extracted DNA. Samples were first heated to lyse target organisms and then added to the chip and filtered through the nanoporous AOM to extract the DNA. PCR reagents were added to each of the wells and the chip was thermocycled. Identification of Streptococcus mutans in a saliva sample is demonstrated along with the detection of 300 fg (100-125 copies) of both methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) genomic DNA (gDNA) spiked into a saliva sample. Multiple target species and strains of bacteria can be simultaneously identified in the same sample by varying the primers and probes used in each of the seven reaction wells. In initial tests, as little as 30 fg (8-12 copies) of MSSA gDNA in buffer has been successfully amplified and detected with this device.

  18. Creating Sub-50 Nm Nanofluidic Junctions in PDMS Microfluidic Chip via Self-Assembly Process of Colloidal Particles.

    PubMed

    Wei, Xi; Syed, Abeer; Mao, Pan; Han, Jongyoon; Song, Yong-Ak

    2016-03-13

    Polydimethylsiloxane (PDMS) is the prevailing building material to make microfluidic devices due to its ease of molding and bonding as well as its transparency. Due to the softness of the PDMS material, however, it is challenging to use PDMS for building nanochannels. The channels tend to collapse easily during plasma bonding. In this paper, we present an evaporation-driven self-assembly method of silica colloidal nanoparticles to create nanofluidic junctions with sub-50 nm pores between two microchannels. The pore size as well as the surface charge of the nanofluidic junction is tunable simply by changing the colloidal silica bead size and surface functionalization outside of the assembled microfluidic device in a vial before the self-assembly process. Using the self-assembly of nanoparticles with a bead size of 300 nm, 500 nm, and 900 nm, it was possible to fabricate a porous membrane with a pore size of ~45 nm, ~75 nm and ~135 nm, respectively. Under electrical potential, this nanoporous membrane initiated ion concentration polarization (ICP) acting as a cation-selective membrane to concentrate DNA by ~1,700 times within 15 min. This non-lithographic nanofabrication process opens up a new opportunity to build a tunable nanofluidic junction for the study of nanoscale transport processes of ions and molecules inside a PDMS microfluidic chip.

  19. Application of a multi-channel microfluidic chip on the simultaneous detection of DNAs by using microbead-quantum dots.

    PubMed

    Le, Ngoc Tam; Kim, Jong Sung

    2014-12-01

    Several researches have shown that cancer is caused by genetic mutations especially in genes involved in cell growth and regulation. Ras family members are frequently found in their mutated, oncogenic forms in human tumors. Mutant RAS proteins are constitutively active, owing to reduce intrinsic GTPase activity and insensitivity to GTPase-activating protein (GAPs). In total, activating mutations in the RAS genes occur in approximately 20% of all human cancers, mainly in codon 12, 13 or 61. Activating mutations in the NRAS gene not only result in the reduction of intrinsic GTPase activity but also in the induction of resistance against molecules inducing such activity. In this paper, we reported a rapid, simple and portable method for detecting the mutant types of NRAS genes codon 12 and 61 simultaneously by using bead-quantum dots (QDs) based multi-channel microfluidic chip. Probe DNAs are conjugated to bead-QDs and packed in the pillars of channels in the microfluidic chip. After injection of target DNAs and intercalating dyes, the fluorescence quenching of QDs by intercalating dye was observed due to FRET phenomena. The platform can be effortlessly applied in other biological and clinical areas.

  20. Comprehensive analysis of alternating current electrokinetics induced motion of colloidal particles in a three-dimensional microfluidic chip

    NASA Astrophysics Data System (ADS)

    Honegger, Thibault; Peyrade, David

    2013-05-01

    AC electrokinetics is becoming a strategic tool for lab-on-a-chip systems due to its versatility and its high level of integration. The ability to foreseen the behaviour of fluids and particles under non-uniform AC electric fields is important to allow new generations of devices. Though most of studies predicted motion of particles in co-planar electrodes configurations, we explore a pure 3-D AC electrokinetic effect that can open the way to enhance contact-less handling throughout the microchannel. By fabricating 3D microfluidic chips with a bi-layer electrodes configuration where electrodes are patterned on both sides of the microfluidic channel, we present a detailed study of the AC electrokinetic regimes that govern particles motion suspended in different host media subjected to a non-uniform AC electric field that spreads through the cross-section of the microchannel. We simulate and observe the motion of 1, 5, and 10 μm polystyrene particles relative to the electrodes and provide an insight on the competition between electro-hydrodynamical forces and dielectrophoresis. We demonstrate that using relevant electrode designs combined with the appropriate applied AC potential, particles can be handled in 3-D in the micro-channel at a single or a collective level in several medium conductivities. Both numerical simulations and experimental results provide a useful basis for future biological applications.

  1. High-throughput and clogging-free microfluidic filtration platform for on-chip cell separation from undiluted whole blood.

    PubMed

    Cheng, Yinuo; Ye, Xiongying; Ma, Zengshuai; Xie, Shuai; Wang, Wenhui

    2016-01-01

    Rapid separation of white blood cells from whole blood sample is often required for their subsequent analyses of functions and phenotypes, and many advances have been made in this field. However, most current microfiltration-based cell separation microfluidic chips still suffer from low-throughput and membrane clogging. This paper reports on a high-throughput and clogging-free microfluidic filtration platform, which features with an integrated bidirectional micropump and commercially available polycarbonate microporous membranes. The integrated bidirectional micropump enables the fluid to flush micropores back and forth, effectively avoiding membrane clogging. The microporous membrane allows red blood cells passing through high-density pores in a cross-flow mixed with dead-end filtration mode. All the separation processes, including blood and buffer loading, separation, and sample collection, are automatically controlled for easy operation and high throughput. Both microbead mixture and undiluted whole blood sample are separated by the platform effectively. In particular, for white blood cell separation, the chip recovered 72.1% white blood cells with an over 232-fold enrichment ratio at a throughput as high as 37.5 μl/min. This high-throughput, clogging-free, and highly integrated platform holds great promise for point-of-care blood pretreatment, analysis, and diagnosis applications.

  2. High-throughput and clogging-free microfluidic filtration platform for on-chip cell separation from undiluted whole blood

    PubMed Central

    Cheng, Yinuo; Ye, Xiongying; Ma, Zengshuai; Xie, Shuai; Wang, Wenhui

    2016-01-01

    Rapid separation of white blood cells from whole blood sample is often required for their subsequent analyses of functions and phenotypes, and many advances have been made in this field. However, most current microfiltration-based cell separation microfluidic chips still suffer from low-throughput and membrane clogging. This paper reports on a high-throughput and clogging-free microfluidic filtration platform, which features with an integrated bidirectional micropump and commercially available polycarbonate microporous membranes. The integrated bidirectional micropump enables the fluid to flush micropores back and forth, effectively avoiding membrane clogging. The microporous membrane allows red blood cells passing through high-density pores in a cross-flow mixed with dead-end filtration mode. All the separation processes, including blood and buffer loading, separation, and sample collection, are automatically controlled for easy operation and high throughput. Both microbead mixture and undiluted whole blood sample are separated by the platform effectively. In particular, for white blood cell separation, the chip recovered 72.1% white blood cells with an over 232-fold enrichment ratio at a throughput as high as 37.5 μl/min. This high-throughput, clogging-free, and highly integrated platform holds great promise for point-of-care blood pretreatment, analysis, and diagnosis applications. PMID:26909124

  3. A coral-on-a-chip microfluidic platform enabling live-imaging microscopy of reef-building corals

    PubMed Central

    Shapiro, Orr H.; Kramarsky-Winter, Esti; Gavish, Assaf R.; Stocker, Roman; Vardi, Assaf

    2016-01-01

    Coral reefs, and the unique ecosystems they support, are facing severe threats by human activities and climate change. Our understanding of these threats is hampered by the lack of robust approaches for studying the micro-scale interactions between corals and their environment. Here we present an experimental platform, coral-on-a-chip, combining micropropagation and microfluidics to allow direct microscopic study of live coral polyps. The small and transparent coral micropropagates are ideally suited for live-imaging microscopy, while the microfluidic platform facilitates long-term visualization under controlled environmental conditions. We demonstrate the usefulness of this approach by imaging coral micropropagates at previously unattainable spatio-temporal resolutions, providing new insights into several micro-scale processes including coral calcification, coral–pathogen interaction and the loss of algal symbionts (coral bleaching). Coral-on-a-chip thus provides a powerful method for studying coral physiology in vivo at the micro-scale, opening new vistas in coral biology. PMID:26940983

  4. A compound magnetic field generating system for targeted killing of Staphylococcus aureus by magnetotactic bacteria in a microfluidic chip

    NASA Astrophysics Data System (ADS)

    Chen, Linjie; Chen, Changyou; Wang, Pingping; Chen, Chuanfang; Wu, Long-Fei; Song, Tao

    2017-04-01

    A compound magnetic field generating system was built to kill Staphylococcus aureus (S. aureus) by magnetotactic bacteria (MTB) in a microfluidic chip in this paper. The system was consisted of coil pairs, a switch circuit, a control program and controllable electrical sources. It could produce a guiding magnetic field (gMF) of ±1 mT along arbitrary direction in the horizontal plane, a rotating magnetic field (rMF) and a swing magnetic field (sMF, 2 Hz, 10 mT) by controlling the currents. The gMF was used to guide MTB swimming to the S. aureus pool in the microfluidic chip, and then the rMF enhanced the mixture of S. aureus and MTB cells, therefore beneficial to the attachments of them. Finally, the sMF was used to induce the death of S. aureus via MTB. The results showed that MTB could be navigated by the gMF and that 47.1% of S. aureus were killed when exposed to the sMF. It provides a new solution for the targeted treatment of infected diseases and even cancers.

  5. Simultaneous analysis of seven oligopeptides in microbial fuel cell by micro-fluidic chip with reflux injection mode.

    PubMed

    Wang, Wei; Wang, Zijian; Lin, Xiuli; Wang, ZongWen; Fu, FengFu

    2012-10-15

    In this work, a reflux injection mode for the cross form micro-fluidic chip was studied. This injection mode could flexibly control the length of sample plug from less than one channel width (<83 μm) to tens of channel widths (millimeter-sized) by adjusting the injection time. Namely, the separation resolution or sample detection sensitivity could be selectively improved by changing injection time. Composed of four steps, the reflux injection mode alleviated the electrophoretic sampling bias and prevented sample leakage successfully. On a micro-fluidic chip coupled with laser induced fluorescence (LIF) detector, the injection mode was applied to separate seven oligopeptides, namely GG, GL, RPP, KPV, VKK, WYD and YWS. All analytes were completely separated and detected within 12 min with detection limits of 25-625 nmol/L. At last, the proposed method had been successfully applied to detect oligopeptides consumed by bacillus licheniformis in anode chamber of microbial fuel cell (MFC) to study the effect of oligopeptides on the MFC running.

  6. High efficiency integration of three-dimensional functional microdevices inside a microfluidic chip by using femtosecond laser multifoci parallel microfabrication

    NASA Astrophysics Data System (ADS)

    Xu, Bing; Du, Wen-Qiang; Li, Jia-Wen; Hu, Yan-Lei; Yang, Liang; Zhang, Chen-Chu; Li, Guo-Qiang; Lao, Zhao-Xin; Ni, Jin-Cheng; Chu, Jia-Ru; Wu, Dong; Liu, Su-Ling; Sugioka, Koji

    2016-01-01

    High efficiency fabrication and integration of three-dimension (3D) functional devices in Lab-on-a-chip systems are crucial for microfluidic applications. Here, a spatial light modulator (SLM)-based multifoci parallel femtosecond laser scanning technology was proposed to integrate microstructures inside a given ‘Y’ shape microchannel. The key novelty of our approach lies on rapidly integrating 3D microdevices inside a microchip for the first time, which significantly reduces the fabrication time. The high quality integration of various 2D-3D microstructures was ensured by quantitatively optimizing the experimental conditions including prebaking time, laser power and developing time. To verify the designable and versatile capability of this method for integrating functional 3D microdevices in microchannel, a series of microfilters with adjustable pore sizes from 12.2 μm to 6.7 μm were fabricated to demonstrate selective filtering of the polystyrene (PS) particles and cancer cells with different sizes. The filter can be cleaned by reversing the flow and reused for many times. This technology will advance the fabrication technique of 3D integrated microfluidic and optofluidic chips.

  7. Separation and determination of β-casomorphins by using glass microfluidic chip electrophoresis together with laser-induced fluorescence detection.

    PubMed

    Wang, ZongWen; Wang, WenJian; Wang, Wei; Xu, LiangJun; Chen, GuoNan; Fu, FengFu

    2011-01-01

    A simple, reliable and reproducible method for the separation and determination of five β-casomorphins (β-CMs, namely TPGN, PGPI, TPGI, TPGP and TPPG) based on glass microfluidic chip electrophoresis and laser-induced fluorescence detection is first described in here. The microfluidic chip electrophoresis and laser-induced fluorescence detection system consisted of a home-made glass "double-T" microchip and a simple LIF detector with excitation and emission wavelengths of 473 and 525 nm, respectively. Fluorescein isothiocyanate (FITC) was used as the precolumn derivatization reagent to label fluorophore on five β-CMs, and the optimum conditions of FITC-derivatization reaction and MCE separation were investigated in detail. Under optimum conditions, five β-CMs were completely separated and detected within 30 min with a detection limit of 18.7-75.1 nmol/L and an RSD (n=5) of 3.0-5.9%, respectively. The proposed method has been successfully used to detect β-CMs in real cheese sample with a recovery of 89-109%, suggesting that our method is sensitive and reliable. These features, as well as its low cost, operation convenience, stability and reusability, make it a promising alternative to β-CMs detection methods. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. High efficiency integration of three-dimensional functional microdevices inside a microfluidic chip by using femtosecond laser multifoci parallel microfabrication

    PubMed Central

    Xu, Bing; Du, Wen-Qiang; Li, Jia-Wen; Hu, Yan-Lei; Yang, Liang; Zhang, Chen-Chu; Li, Guo-Qiang; Lao, Zhao-Xin; Ni, Jin-Cheng; Chu, Jia-Ru; Wu, Dong; Liu, Su-Ling; Sugioka, Koji

    2016-01-01

    High efficiency fabrication and integration of three-dimension (3D) functional devices in Lab-on-a-chip systems are crucial for microfluidic applications. Here, a spatial light modulator (SLM)-based multifoci parallel femtosecond laser scanning technology was proposed to integrate microstructures inside a given ‘Y’ shape microchannel. The key novelty of our approach lies on rapidly integrating 3D microdevices inside a microchip for the first time, which significantly reduces the fabrication time. The high quality integration of various 2D-3D microstructures was ensured by quantitatively optimizing the experimental conditions including prebaking time, laser power and developing time. To verify the designable and versatile capability of this method for integrating functional 3D microdevices in microchannel, a series of microfilters with adjustable pore sizes from 12.2 μm to 6.7 μm were fabricated to demonstrate selective filtering of the polystyrene (PS) particles and cancer cells with different sizes. The filter can be cleaned by reversing the flow and reused for many times. This technology will advance the fabrication technique of 3D integrated microfluidic and optofluidic chips. PMID:26818119

  9. Chemiluminescence determination of moxifloxacin in pharmaceutical and biological samples based on its enhancing effect of the luminol-ferricyanide system using a microfluidic chip.

    PubMed

    Suh, Yeoun Suk; Kamruzzaman, Mohammad; Alam, Al-Mahmnur; Lee, Sang Hak; Kim, Young Ho; Kim, Gyu-Man; Dang, Trung Dung

    2014-05-01

    A sensitive determination of a synthetic fluoroquinolone antibacterial agent, moxifloxacin (MOX), by an enhanced chemiluminescence (CL) method using a microfluidic chip is described. The microfluidic chip was fabricated by a soft-lithographic procedure using polydimethyl siloxane (PDMS). The fabricated PDMS microfluidic chip had three-inlet microchannels for introducing the sample, chemiluminescent reagent and oxidant, and a 500 µm wide, 250 µm deep and 82 mm long microchannel. An enhanced CL system, luminol-ferricyanide, was adopted to analyze the MOX concentration in a sample solution. CL light was emitted continuously after mixing luminol and ferricyanide in the presence of MOX on the PDMS microfluidic chip. The amount of MOX in the luminol-ferricyanide system influenced the intensity of the CL light. The linear range of MOX concentration was 0.14-55.0 ng/mL with a correlation coefficient of 0.9992. The limit of detection (LOD) and limit of quantification (LOQ) were 0.06 and 0.2 ng/mL respectively. The presented method afforded good reproducibility, with a relative standard deviation (RSD) of 1.05% for 10 ng/mL of MOX, and has been successfully applied for the determination of MOX in pharmaceutical and biological samples.

  10. 10,000-fold concentration increase of the biomarker cardiac troponin I in a reducing union microfluidic chip using cationic isotachophoresis.

    PubMed

    Bottenus, Danny; Jubery, Talukder Zaki; Ouyang, Yexin; Dong, Wen-Ji; Dutta, Prashanta; Ivory, Cornelius F

    2011-03-07

    This paper describes the preconcentration of the biomarker cardiac troponin I (cTnI) and a fluorescent protein (R-phycoerythrin) using cationic isotachophoresis (ITP) in a 3.9 cm long poly(methyl methacrylate) (PMMA) microfluidic chip. The microfluidic chip includes a channel with a 5× reduction in depth and a 10× reduction in width. Thus, the overall cross-sectional area decreases by 50× from inlet (anode) to outlet (cathode). The concentration is inversely proportional to the cross-sectional area so that as proteins migrate through the reductions, the concentrations increase proportionally. In addition, the proteins gain additional concentration by ITP. We observe that by performing ITP in a cross-sectional area reducing microfluidic chip we can attain concentration factors greater than 10,000. The starting concentration of cTnI was 2.3 μg mL⁻¹ and the final concentration after ITP concentration in the microfluidic chip was 25.52 ± 1.25 mg mL⁻¹. To the author's knowledge this is the first attempt at concentrating the cardiac biomarker cTnI by ITP. This experimental approach could be coupled to an immunoassay based technique and has the potential to lower limits of detection, increase sensitivity, and quantify different isolated cTnI phosphorylation states.

  11. Microfluidic on-chip biomimicry for 3D cell culture: a fit-for-purpose investigation from the end user standpoint.

    PubMed

    Liu, Ye; Gill, Elisabeth; Shery Huang, Yan Yan

    2017-06-01

    A plethora of 3D and microfluidics-based culture models have been demonstrated in the recent years with the ultimate aim to facilitate predictive in vitro models for pharmaceutical development. This article summarizes to date the progress in the microfluidics-based tissue culture models, including organ-on-a-chip and vasculature-on-a-chip. Specific focus is placed on addressing the question of what kinds of 3D culture and system complexities are deemed desirable by the biological and biomedical community. This question is addressed through analysis of a research survey to evaluate the potential use of microfluidic cell culture models among the end users. Our results showed a willingness to adopt 3D culture technology among biomedical researchers, although a significant gap still exists between the desired systems and existing 3D culture options. With these results, key challenges and future directions are highlighted.

  12. Microfluidic on-chip biomimicry for 3D cell culture: a fit-for-purpose investigation from the end user standpoint

    PubMed Central

    Liu, Ye; Gill, Elisabeth; Shery Huang, Yan Yan

    2017-01-01

    A plethora of 3D and microfluidics-based culture models have been demonstrated in the recent years with the ultimate aim to facilitate predictive in vitro models for pharmaceutical development. This article summarizes to date the progress in the microfluidics-based tissue culture models, including organ-on-a-chip and vasculature-on-a-chip. Specific focus is placed on addressing the question of what kinds of 3D culture and system complexities are deemed desirable by the biological and biomedical community. This question is addressed through analysis of a research survey to evaluate the potential use of microfluidic cell culture models among the end users. Our results showed a willingness to adopt 3D culture technology among biomedical researchers, although a significant gap still exists between the desired systems and existing 3D culture options. With these results, key challenges and future directions are highlighted. PMID:28670465

  13. Hybrid microfluidic systems: combining a polymer microfluidic toolbox with biosensors

    NASA Astrophysics Data System (ADS)

    Gärtner, Claudia; Kirsch, Stefanie; Anton, Birgit; Becker, Holger

    2007-01-01

    In this paper we present polymer based microfluidic chips which contain functional elements (electrodes, biosensors) made out of a different material (metals, silicon, organic semiconductors). These hybrid microfluidic devices allow the integration of additional functionality other than the simple manipulation of liquids in the chip and have been developed as a reaction to the increasing requirement for functional integration in microfluidics.

  14. Fabrication and assembling of a microfluidic optical stretcher polymeric chip combining femtosecond laser and micro injection molding technologies

    NASA Astrophysics Data System (ADS)

    Volpe, Annalisa; Ancona, Antonio; Trotta, Gianluca; Martínez Vázquez, Rebeca; Fassi, Irene; Osellame, Roberto

    2017-02-01

    Microfluidic optical stretchers are valuable optofluidic devices for studying single cell mechanical properties. These usually consist of a single microfluidic channel where cells, with dimensions ranging from 5 to 20 μm are trapped and manipulated through optical forces induced by two counter-propagating laser beams. Recently, monolithic optical stretchers have been directly fabricated in fused silica by femtosecond laser micromachining (FLM). Such a technology allows writing in a single step in the substrate volume both the microfluidic channel and the optical waveguides with a high degree of precision and flexibility. However, this method is very slow and cannot be applied to cheaper materials like polymers. Therefore, novel technological platforms are needed to boost the production of such devices on a mass scale. In this work, we propose integration of FLM with micro-injection moulding (μIM) as a novel route towards the cost-effective and flexible manufacturing of polymeric Lab-on-a-Chip (LOC) devices. In particular, we have fabricated and assembled a polymethylmethacrylate (PMMA) microfluidic optical stretcher by exploiting firstly FLM to manufacture a metallic mould prototype with reconfigurable inserts. Afterwards, such mould was employed for the production, through μIM, of the two PMMA thin plates composing the device. The microchannel with reservoirs and lodgings for the optical fibers delivering the laser radiation for cell trapping were reproduced on one plate, while the other included access holes to the channel. The device was assembled by direct fs-laser welding, ensuring sealing of the channel and avoiding thermal deformation and/or contamination.

  15. In-Depth Characterization of N-Linked Oligosaccharides Using Fluoride-Mediated Negative Ion Microfluidic Chip LC-MS

    PubMed Central

    Ni, Wenqin; Bones, Jonathan; Karger, Barry L.

    2013-01-01

    Characterization of N-glycans by liquid chromatography-positive electrospray ionization (ESI) tandem mass spectrometry (LC-MS/MS) using a microfluidic chip packed with porous graphitized carbon (PGC) represents a rapidly developing area in oligosaccharide analysis. Positive ion ESI-MS generates B/Y-type glycosidic fragment ions under collisional induced dissociation (CID). Although these ions facilitate glycan sequencing, they provide little information on linkage and positional isomers. Isomer identification in these cases is by retention on the PGC stationary phase where the specific structural isomers can, in principle, be separated. In this paper, we broaden the applicability of the PGC microfluidic chip/MS platform by implementing fluoride-mediated negative ESI-MS. Ammonium fluoride, added to the mobile phase, aids in the formation of pseudomolecular oligosaccharide anions due to the ability of fluoride to abstract a proton from the glycan structure. The negative charge results in the generation of C-type glycosidic fragments, highly informative A-type cross ring fragment ions and additional gas phase ion reaction products (e.g., D- and E-type ions), which, when combined, lead to in-depth oligosaccharide characterization, including linkage and positional isomers. Due to the separation of anomers by the PGC phase, comparison of oligosaccharides with an intact reducing terminus to their corresponding alditols was performed, revealing a more sensitive MS and, especially, MS/MS response from the glycans with a free reducing end. Fluoride also ensured recovery of charged oligosaccharides from the PGC stationary phase. Application to the characterization of N-glycans released from polyclonal human and murine serum IgG is presented to demonstrate the effectiveness of the chip/negative ESI approach. PMID:23398125

  16. Research to Improve the Efficiency of Double Stereo PCR Microfluidic Chip by Passivating the Inner Surface of Steel Capillary with NOA61.

    PubMed

    Wu, Jian; Guo, Wei; Wang, Chunyan; Yu, Kuanxin; Ma, Ying; Chen, Tao; Li, Yinghui

    2015-06-01

    In this paper, we report the improvement of PCR microfluidic chip efficiency achieved by coating the inner surface of steel capillary microchannel with a 22-µm film of the ultraviolet-solidified NOA61 using a device invented by us. Our results indicate that with this treatment, the roughness of the inside wall of steel capillary was improved from Ra = 0.921 to Ra = 0.254. The contact angle was decreased from about 95° to 56°, and the surface hydrophobicity was also increased. The flow pressure for performing the real-time PCR in the microfluidic chip with modified surface was reduced by twofold (2.11/1) and that resulted in a substantially increased efficiency of PCR. A modification of the microchannel interior surface improved the quality of the on-chip integrated PCR procedure.

  17. Rapid on-chip recalcification and drug dosing of citrated whole blood using microfluidic buffer sheath flow.

    PubMed

    Muthard, Ryan W; Diamond, Scott L

    2014-01-01

    Millions of clotting tests each year require recalcification of blood treated with sodium citrate, a calcium chelator that prevents prothrombinase assembly. We validated a converging trifurcated microfluidic device to measure platelet and fibrin accumulation following on-chip recalcification of citrated whole blood. Recalcification was accomplished by sheathing the blood with Ca2+ buffer. Fluorescein rapidly diffused across the buffer-blood interface (achieving 62.5% of maximum centerline concentration within ~4 cm of flow), while albumin remained relatively unchanged in blood due to its lower diffusivity (<20% decrease). Since Ca2+ diffuses faster than fluorescein, full recalcification of whole blood was achieved within ~1 cm of flow prior to encountering a collagen/tissue surface. Platelet and fibrin were reduced by 87.3% and 99.0%, respectively, when the sheath buffer was Ca2+-free. A 30-min preincubation of citrated whole blood prior to on-chip recalcification increased platelet (159%) and fibrin (86.6%) deposition, compared to 5-min preincubation, likely due to factor XIIa generation in citrated blood. The P2Y1 inhibitor, MRS-2179, was delivered by diffusion into flowing blood and inhibited platelet deposition on collagen with a calculated IC50 of 0.155 μM. On-chip recalcification and drug dosing of citrated blood allows for assays of platelet function in a whole blood milieu under flow.

  18. Nanoelectromechanical Chip (NELMEC) Combination of Nanoelectronics and Microfluidics to Diagnose Epithelial and Mesenchymal Circulating Tumor Cells from Leukocytes.

    PubMed

    Hosseini, Seied Ali; Abdolahad, Mohammad; Zanganeh, Somayeh; Dahmardeh, Mahyar; Gharooni, Milad; Abiri, Hamed; Alikhani, Alireza; Mohajerzadeh, Shams; Mashinchian, Omid

    2016-02-17

    An integrated nano-electromechanical chip (NELMEC) has been developed for the label-free distinguishing of both epithelial and mesenchymal circulating tumor cells (ECTCs and MCTCs, respectively) from white blood cells (WBCs). This nanoelectronic microfluidic chip fabricated by silicon micromachining can trap large single cells (>12 µm) at the opening of the analysis microchannel arrays. The nature of the captured cells is detected using silicon nanograss (SiNG) electrodes patterned at the entrance of the channels. There is an observable difference between the membrane capacitance of the ECTCs and MCTCs and that of WBCs (measured using SiNG electrodes), which is the key indication for our diagnosis. The NELMEC chip not only solves the problem of the size overlap between CTCs and WBCs but also detects MCTCs without the need for any markers or tagging processes, which has been an important problem in previously reported CTC detection systems. The great conductivity of the gold-coated SiNG nanocontacts as well as their safe penetration into the membrane of captured cells, facilitate a precise and direct signal extraction to distinguish the type of captured cell. The results achieved from epithelial (MCF-7) and mesenchymal (MDA-MB231) breast cancer cells circulated in unprocessed blood suggest the significant applications for these diagnostic abilities of NELMEC. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Coupling paper-based microfluidics and lab on a chip technologies for confirmatory analysis of trinitro aromatic explosives.

    PubMed

    Pesenti, Alessandra; Taudte, Regina Verena; McCord, Bruce; Doble, Philip; Roux, Claude; Blanes, Lucas

    2014-05-20

    A new microfluidic paper-based analytical device (μPAD) in conjunction with confirmation by a lab on chip analysis was developed for detection of three trinitro aromatic explosives. Potassium hydroxide was deposited on the μPADs (0.5 μL, 1.5 M), creating a color change reaction when explosives are present, with detection limits of approximately 7.5 ± 1.0 ng for TNB, 12.5 ± 2.0 ng for TNT and 15.0 ± 2.0 ng for tetryl. For confirmatory analysis, positive μPADs were sampled using a 5 mm hole-punch, followed by extraction of explosives from the punched chad in 30 s using 20 μL borate/SDS buffer. The extractions had efficiencies of 96.5 ± 1.7%. The extracted explosives were then analyzed with the Agilent 2100 Bioanalyzer lab on a chip device with minimum detectable amounts of 3.8 ± 0.1 ng for TNB, 7.0 ± 0.9 ng for TNT, and 4.7 ± 0.2 ng for tetryl. A simulated in-field scenario demonstrated the feasibility of coupling the μPAD technique with the lab on a chip device to detect and identify 1 μg of explosives distributed on a surface of 100 cm(2).

  20. A dual-docking microfluidic cell migration assay (D(2)-Chip) for testing neutrophil chemotaxis and the memory effect.

    PubMed

    Yang, Ke; Wu, Jiandong; Xu, Guoqing; Xie, Dongxue; Peretz-Soroka, Hagit; Santos, Susy; Alexander, Murray; Zhu, Ling; Zhang, Michael; Liu, Yong; Lin, Francis

    2017-04-18

    Chemotaxis is a classic mechanism for guiding cell migration and an important topic in both fundamental cell biology and health sciences. Neutrophils are a widely used model to study eukaryotic cell migration and neutrophil chemotaxis itself can lead to protective or harmful immune actions to the body. While much has been learnt from past research about how neutrophils effectively navigate through a chemoattractant gradient, many interesting questions remain unclear. For example, while it is tempting to model neutrophil chemotaxis using the well-established biased random walk theory, the experimental proof was challenged by the cell's highly persistent migrating nature. A special experimental design is required to test the key predictions from the random walk model. Another question that has interested the cell migration community for decades concerns the existence of chemotactic memory and its underlying mechanism. Although chemotactic memory has been suggested in various studies, a clear quantitative experimental demonstration will improve our understanding of the migratory memory effect. Motivated by these questions, we developed a microfluidic cell migration assay (so-called dual-docking chip or D(2)-Chip) that can test both the biased random walk model and the memory effect for neutrophil chemotaxis on a single chip enabled by multi-region gradient generation and dual-region cell alignment. Our results provide experimental support for the biased random walk model and chemotactic memory for neutrophil chemotaxis. Quantitative data analyses provide new insights into neutrophil chemotaxis and memory by making connections to entropic disorder, cell morphology and oscillating migratory response.

  1. Using inexpensive Jell-O chips for hands-on microfluidics education.

    PubMed

    Yang, Cheng Wei T; Ouellet, Eric; Lagally, Eric T

    2010-07-01

    As the field of microfluidics continues to grow, there is an increasing demand for public education about this technology. This article presents a quick, simple, safe, and inexpensive method for teaching microfluidics to younger students and the general public. (To listen to a podcast about this article, please go to the Analytical Chemistry multimedia page at pubs.acs.org/page/ancham/audio/index.html .).

  2. Brain slice on a chip: opportunities and challenges of applying microfluidic technology to intact tissues.

    PubMed

    Huang, Yu; Williams, Justin C; Johnson, Stephen M

    2012-06-21

    Isolated brain tissue, especially brain slices, are valuable experimental tools for studying neuronal function at the network, cellular, synaptic, and single channel levels. Neuroscientists have refined the methods for preserving brain slice viability and function and converged on principles that strongly resemble the approach taken by engineers in developing microfluidic devices. With respect to brain slices, microfluidic technology may 1) overcome the traditional limitations of conventional interface and submerged slice chambers and improve oxygen/nutrient penetration into slices, 2) provide better spatiotemporal control over solution flow/drug delivery to specific slice regions, and 3) permit successful integration with modern optical and electrophysiological techniques. In this review, we highlight the unique advantages of microfluidic devices for in vitro brain slice research, describe recent advances in the integration of microfluidic devices with optical and electrophysiological instrumentation, and discuss clinical applications of microfluidic technology as applied to brain slices and other non-neuronal tissues. We hope that this review will serve as an interdisciplinary guide for both neuroscientists studying brain tissue in vitro and engineers as they further develop microfluidic chamber technology for neuroscience research.

  3. Microfluidic chip-based nano-liquid chromatography tandem mass spectrometry for quantification of aflatoxins in peanut products.

    PubMed

    Liu, Hsiang-Yu; Lin, Shu-Ling; Chan, Shan-An; Lin, Tzuen-Yeuan; Fuh, Ming-Ren

    2013-09-15

    Aflatoxins (AFs), a group of mycotoxins, are generally produced by fungi Aspergillus species. The naturally occurring AFs including AFB1, AFB2, AFG1, and AFG2 have been clarified as group 1 human carcinogen by International Agency for Research on Cancer. Developing a sensitive analytical method has become an important issue to accurately quantify trace amount of AFs in foodstuffs. In this study, we employed a microfluidic chip-based nano LC (chip-nanoLC) coupled to triple quadrupole mass spectrometer (QqQ-MS) system for the quantitative determination of AFs in peanuts and related products. Gradient elution and multiple reaction monitoring were utilized for chromatographic separation and MS measurements. Solvent extraction followed by immunoaffinity solid-phase extraction was employed to isolate analytes and reduce matrix effect from sample prior to chip-nanoLC/QqQ-MS analysis. Good recoveries were found to be in the range of 90.8%-100.4%. The linear range was 0.048-16 ng g(-1) for AFB1, AFB2, AFG1, AFG2 and AFM1. Limits of detection were estimated as 0.004-0.008 ng g(-1). Good intra-day/inter-day precision (2.3%-9.5%/2.3%-6.6%) and accuracy (96.1%-105.7%/95.5%-104.9%) were obtained. The applicability of this newly developed chip-nanoLC/QqQ-MS method was demonstrated by determining the AFs in various peanut products purchased from local markets. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Fabrication of universal serial bus flash disk type microfluidic chip electrophoresis and application for protein analysis under ultra low voltage

    PubMed Central

    Cong, Hailin; Xu, Xiaodan; Yu, Bing; Liu, Huwei

    2016-01-01

    A simple and effective universal serial bus (USB) flash disk type microfluidic chip electrophoresis (MCE) was developed by using poly(dimethylsiloxane) based soft lithography and dry film based printed circuit board etching techniques in this paper. The MCE had a microchannel diameter of 375 μm and an effective length of 25 mm. Equipped with a conventional online electrochemical detector, the device enabled effectively separation of bovine serum albumin, lysozyme, and cytochrome c in 80 s under the ultra low voltage from a computer USB interface. Compared with traditional capillary electrophoresis, the USB flash disk type MCE is not only portable and inexpensive but also fast with high separation efficiency. PMID:27042249

  5. Capacitance variation induced by microfluidic two-phase flow across insulated interdigital electrodes in lab-on-chip devices.

    PubMed

    Dong, Tao; Barbosa, Cátia

    2015-01-26

    Microfluidic two-phase flow detection has attracted plenty of interest in various areas of biology, medicine and chemistry. This work presents a capacitive sensor using insulated interdigital electrodes (IDEs) to detect the presence of droplets in a microchannel. This droplet sensor is composed of a glass substrate, patterned gold electrodes and an insulation layer. A polydimethylsiloxane (PDMS) cover bonded to the multilayered structure forms a microchannel. Capacitance variation induced by the droplet passage was thoroughly investigated with both simulation and experimental work. Olive oil and deionized water were employed as the working fluids in the experiments to demonstrate the droplet sensor. The results show a good sensitivity of the droplet with the appropriate measurement connection. This capacitive droplet sensor is promising to be integrated into a lab-on-chip device for in situ monitoring/counting of droplets or bubbles.

  6. Fabrication of universal serial bus flash disk type microfluidic chip electrophoresis and application for protein analysis under ultra low voltage.

    PubMed

    Cong, Hailin; Xu, Xiaodan; Yu, Bing; Liu, Huwei; Yuan, Hua

    2016-03-01

    A simple and effective universal serial bus (USB) flash disk type microfluidic chip electrophoresis (MCE) was developed by using poly(dimethylsiloxane) based soft lithography and dry film based printed circuit board etching techniques in this paper. The MCE had a microchannel diameter of 375 μm and an effective length of 25 mm. Equipped with a conventional online electrochemical detector, the device enabled effectively separation of bovine serum albumin, lysozyme, and cytochrome c in 80 s under the ultra low voltage from a computer USB interface. Compared with traditional capillary electrophoresis, the USB flash disk type MCE is not only portable and inexpensive but also fast with high separation efficiency.

  7. Lab-on-chip microfluidic impedance measurement for laminar flow ratio sensing and differential conductivity difference detection

    NASA Astrophysics Data System (ADS)

    Kong, Tian Fook; Shen, Xinhui; Marcos, Yang, Chun

    2017-06-01

    We present a microfluidic impedance device for achieving both the flow ratio sensing and the conductivity difference detection between sample stream and reference buffer. By using a flow focusing configuration, with the core flow having a higher conductivity sample than the sheath flow streams, the conductance of the device varies linearly with the flow ratio, with R2 > 0.999. On the other hand, by using deionized (DI)-water sheath flow as a reference, we can detect the difference in conductivity between the buffer of core flow and sheath DI-water with a high detection sensitivity of up to 1 nM of sodium chloride solution. Our study provides a promising approach for on-chip flow mixing characterization and bacteria detection.

  8. A portable instrument for continuous glucose monitoring by the integration of microfluidic chip and micro-glucose sensor

    NASA Astrophysics Data System (ADS)

    Li, Dachao; Ji, Yongjie; Liang, Wenshuai; Zhang, Xiaoli; Yu, Haixia; Xu, Kexin

    2013-03-01

    Interstitial fluid (ISF) can be transdermally extracted using low-frequency ultrasound and continuous vacuum pressure on skin surface. But the tiny volume of transdermally extracted ISF makes the transdermal extraction, collection, transport, volumetric detection and glucose concentration measurement of the ISF very difficult. Based on a microfluidic chip for transdermally extraction of interstitial fluid and a micro glucose sensor for glucose concentration measurement, a continuous glucose monitoring instrumentby ISF transdermal extraction with minimally invasive way is developed. In the paper, various parts of the device and their interface circuits are designed; the hardware and software of the instrument are built; the simulating experiments of transdermal ISF extraction, collection and volume measurement with full-thickness pig skin are performed using this integrated system; and the functionalities of this device is verified for future clinical application.

  9. Design of a Microfluidic Chip for Magnetic-Activated Sorting of One-Bead-One-Compound Libraries.

    PubMed

    Cho, Choi-Fong; Lee, Kyungheon; Speranza, Maria-Carmela; Bononi, Fernanda C; Viapiano, Mariano S; Luyt, Leonard G; Weissleder, Ralph; Chiocca, E Antonio; Lee, Hakho; Lawler, Sean E

    2016-06-13

    Molecular targeting using ligands specific to disease markers has shown great promise for early detection and directed therapy. Bead-based combinatorial libraries have served as powerful tools for the discovery of novel targeting agents. Screening platforms employing magnetic capture have been used to achieve rapid and efficient identification of high-affinity ligands from one-bead-one-compound (OBOC) libraries. Traditional manual methodologies to isolate magnetized "hit" beads are tedious and lack accuracy, and existing instruments to expedite bead sorting tend to be costly and complex. Here, we describe the design and construction of a simple and inexpensive microfluidic magnetic sorting device using standard photolithography and soft lithography approaches to facilitate high-throughput isolation of magnetized positive hit beads from combinatorial libraries. We have demonstrated that the device is able to sort magnetized beads with superior accuracy compared to conventional manual sorting approaches. This chip offers a very convenient yet inexpensive alternative for screening OBOC libraries.

  10. Fast single run of vanilla fingerprint markers on microfluidic-electrochemistry chip for confirmation of common frauds.

    PubMed

    Avila, Mónica; Zougagh, Mohammed; Escarpa, Alberto; Ríos, Angel

    2009-10-01

    A new strategy based on the fast separation of the fingerprint markers of Vanilla planifolia extracts and vanilla-related samples on microfluidic-electrochemistry chip is proposed. This methodology allowed the detection of all required markers for confirmation of common frauds in this field. The elution order was strategically connected with sequential sample screening and analyte confirmation steps, where first ethyl vanillin was detected to distinguish natural from adultered samples; second, vanillin as prominent marker in V. planifolia, but frequently added in its synthetic form; and third, the final detection of the fingerprint markers (p-hydroxybenzaldehyde, vanillic acid, and p-hydroxybenzoic acid) of V. planifolia with confirmation purposes. The reliability of the proposed methodology was demonstrated in the confirmation the natural or non-natural origin of vanilla in samples using V. planifolia extracts and other selected food samples containing this flavor.

  11. Microfluidic chip based micro RNA detection through the combination of fluorescence and surface enhanced Raman scattering techniques.

    PubMed

    Wang, Zhile; Zong, Shenfei; Wang, Zhuyuan; Wu, Lei; Chen, Peng; Yun, Binfeng; Cui, Yiping

    2017-03-10

    We present a novel microfluidic chip based method for the detection of micro RNA (miRNA) via the combination of fluorescence and surface enhanced Raman scattering (SERS) spectroscopies. First, silver nanoparticles (Ag NPs) are immobilized onto a glass slide, forming a SERS enhancing substrate. Then a specificially designed molecular beacon (MB) is attached to the SERS substrate. The 3' end of the MB is decorated with a thiol group to facilitate the attachment of the MB, while the 5' end of the MB is labeled with an organic dye 6-FAM, which is used both as the fluorophore and SERS reporter. In the absence of target miRNA, the MB will form a hairpin structure, making 6-FAM close to the Ag NPs. Hence, the fluorescence of 6-FAM will be quenched and the Raman signal of 6-FAM will be enhanced. On the contrary, with target miRNA present, hybridization between the miRNA and MB will unfold the MB and increase the distance between 6-FAM and the Ag NPs. Thus the fluorescence of 6-FAM will recover and the SERS signal of 6-FAM will decrease. So the target miRNA will simultaneously introduce opposite changing trends in the intensities of the fluorescence and SERS signals. By combining the opposite changes in the two optical spectra, an improved sensitivity and linearity toward the target miRNA is achieved as compared with using solely fluorescence or SERS. Moreover, introducing the microfluidic chip can reduce the reaction time, reagent dosage and complexity of detection. With the improved sensitivity and simplicity, we anticipate that the presented method can have great potential in the investigation of miRNA related diseases.

  12. Microfluidic chip based micro RNA detection through the combination of fluorescence and surface enhanced Raman scattering techniques

    NASA Astrophysics Data System (ADS)

    Wang, Zhile; Zong, Shenfei; Wang, Zhuyuan; Wu, Lei; Chen, Peng; Yun, Binfeng; Cui, Yiping

    2017-03-01

    We present a novel microfluidic chip based method for the detection of micro RNA (miRNA) via the combination of fluorescence and surface enhanced Raman scattering (SERS) spectroscopies. First, silver nanoparticles (Ag NPs) are immobilized onto a glass slide, forming a SERS enhancing substrate. Then a specificially designed molecular beacon (MB) is attached to the SERS substrate. The 3‧ end of the MB is decorated with a thiol group to facilitate the attachment of the MB, while the 5‧ end of the MB is labeled with an organic dye 6-FAM, which is used both as the fluorophore and SERS reporter. In the absence of target miRNA, the MB will form a hairpin structure, making 6-FAM close to the Ag NPs. Hence, the fluorescence of 6-FAM will be quenched and the Raman signal of 6-FAM will be enhanced. On the contrary, with target miRNA present, hybridization between the miRNA and MB will unfold the MB and increase the distance between 6-FAM and the Ag NPs. Thus the fluorescence of 6-FAM will recover and the SERS signal of 6-FAM will decrease. So the target miRNA will simultaneously introduce opposite changing trends in the intensities of the fluorescence and SERS signals. By combining the opposite changes in the two optical spectra, an improved sensitivity and linearity toward the target miRNA is achieved as compared with using solely fluorescence or SERS. Moreover, introducing the microfluidic chip can reduce the reaction time, reagent dosage and complexity of detection. With the improved sensitivity and simplicity, we anticipate that the presented method can have great potential in the investigation of miRNA related diseases.

  13. Evaluation of the effect of the structure of bacterial cellulose on full thickness skin wound repair on a microfluidic chip.

    PubMed

    Li, Ying; Wang, Shiwen; Huang, Rong; Huang, Zhuo; Hu, Binfeng; Zheng, Wenfu; Yang, Guang; Jiang, Xingyu

    2015-03-09

    Bacterial cellulose (BC) is a kind of nanobiomaterial for tissue engineering. How the nanoscale structure of BC affects skin wound repair is unexplored. Here, the hierarchical structure of BC films and their different effects on skin wound healing were studied both in vitro and in vivo. The bottom side of the BC film had a larger pore size, and a looser and rougher structure than that of the top side. By using a microfluidics-based in vitro wound healing model, we revealed that the bottom side of the BC film can better promote the migration of cells to facilitate wound healing. Furthermore, the full-thickness skin wounds on Wistar rats demonstrated that, compared with gauze and the top side of the BC film, the wound covered by the bottom side of the BC film showed faster recovery rate and less inflammatory response. The results indicate that the platform based on the microfluidic chip provide a rapid, reliable, and repeatable method for wound dressing screening. As an excellent biomaterial for wound healing, the BC film displays different properties on different sides, which not only provides a method to optimize the biocompatibility of wound dressings but also paves a new way to building heterogeneous BC-based biomaterials for complex tissue engineering.

  14. Low-temperature bonded glass-membrane microfluidic device for in vitro organ-on-a-chip cell culture models

    NASA Astrophysics Data System (ADS)

    Pocock, Kyall J.; Gao, Xiaofang; Wang, Chenxi; Priest, Craig; Prestidge, Clive A.; Mawatari, Kazuma; Kitamori, Takehiko; Thierry, Benjamin

    2015-12-01

    The integration of microfluidics with living biological systems has paved the way to the exciting concept of "organson- a-chip", which aims at the development of advanced in vitro models that replicate the key features of human organs. Glass based devices have long been utilised in the field of microfluidics but the integration of alternative functional elements within multi-layered glass microdevices, such as polymeric membranes, remains a challenge. To this end, we have extended a previously reported approach for the low-temperature bonding of glass devices that enables the integration of a functional polycarbonate porous membrane. The process was initially developed and optimised on specialty low-temperature bonding equipment (μTAS2001, Bondtech, Japan) and subsequently adapted to more widely accessible hot embosser units (EVG520HE Hot Embosser, EVG, Austria). The key aspect of this method is the use of low temperatures compatible with polymeric membranes. Compared to borosilicate glass bonding (650 °C) and quartz/fused silica bonding (1050 °C) processes, this method maintains the integrity and functionality of the membrane (Tg 150 °C for polycarbonate). Leak tests performed showed no damage or loss of integrity of the membrane for up to 150 hours, indicating sufficient bond strength for long term cell culture. A feasibility study confirmed the growth of dense and functional monolayers of Caco-2 cells within 5 days.

  15. Stable, Free-space Optical Trapping and Manipulation of Sub-micron Particles in an Integrated Microfluidic Chip.

    PubMed

    Kim, Jisu; Shin, Jung H

    2016-09-22

    We demonstrate stable, free-space optical trapping and manipulation in an integrated microfluidic chip using counter-propagating beams. An inverted ridge-type waveguide made of SU8 is cut across by an open trench. The design of the waveguide provides low propagation losses and small divergence of the trapping beam upon emergence from the facet, and the trench designed to be deeper and wider than the optical mode enables full utilization of the optical power with an automatic alignment for counter-propagating beams in a trap volume away from all surfaces. After integration with polydimethylsiloxane (PDMS) microfluidic channel for particle delivery, 0.65 μm and 1 μm diameter polystyrene beads were trapped in free space in the trench, and manipulated to an arbitrary position between the waveguides with a resolution of < 100 nm. Comparison with numerical simulations confirm stable trapping of sub-micron particles, with a 10 kBT threshold power of less than 1 mW and a stiffness that can be 1 order of magnitude larger than that of comparable fiber-based trapping methods.

  16. Microfluidic Chip-Based Online Screening Coupled to Mass Spectrometry: Identification of Inhibitors of Thrombin and Factor Xa.

    PubMed

    Iyer, Janaki Krishnamoorthy; Otvos, Reka A; Kool, Jeroen; Kini, R Manjunatha

    2016-02-01

    Thrombin and factor Xa (FXa) are critical enzymes of the blood coagulation cascade and are excellent targets of anticoagulant agents. Natural sources present an array of anticoagulants that can be developed as antithrombotic drugs. High-resolution, online screening techniques have been developed for the identification of drug leads from complex mixtures. In this study, we have developed and optimized a microfluidic online screening technique coupled to nano-liquid chromatography (LC) and in parallel with a mass spectrometer for the identification of thrombin and FXa inhibitors in mixtures. Inhibitors eluting from the nano-LC were split postcolumn in a 1:1 ratio; half was fed into a mass spectrometer (where its mass is detected), and the other half was fed into a microfluidic chip (which acts as a microreactor for the online assays). With our platform, thrombin and FXa inhibitors were detected in the assay in parallel with their mass identification. These methods are suitable for the identification of inhibitors from sample amounts as low as sub-microliter volumes.

  17. Stable, Free-space Optical Trapping and Manipulation of Sub-micron Particles in an Integrated Microfluidic Chip

    PubMed Central

    Kim, Jisu; Shin, Jung H.

    2016-01-01

    We demonstrate stable, free-space optical trapping and manipulation in an integrated microfluidic chip using counter-propagating beams. An inverted ridge-type waveguide made of SU8 is cut across by an open trench. The design of the waveguide provides low propagation losses and small divergence of the trapping beam upon emergence from the facet, and the trench designed to be deeper and wider than the optical mode enables full utilization of the optical power with an automatic alignment for counter-propagating beams in a trap volume away from all surfaces. After integration with polydimethylsiloxane (PDMS) microfluidic channel for particle delivery, 0.65 μm and 1 μm diameter polystyrene beads were trapped in free space in the trench, and manipulated to an arbitrary position between the waveguides with a resolution of < 100 nm. Comparison with numerical simulations confirm stable trapping of sub-micron particles, with a 10 kBT threshold power of less than 1 mW and a stiffness that can be 1 order of magnitude larger than that of comparable fiber-based trapping methods. PMID:27653191

  18. Stable, Free-space Optical Trapping and Manipulation of Sub-micron Particles in an Integrated Microfluidic Chip

    NASA Astrophysics Data System (ADS)

    Kim, Jisu; Shin, Jung H.

    2016-09-01

    We demonstrate stable, free-space optical trapping and manipulation in an integrated microfluidic chip using counter-propagating beams. An inverted ridge-type waveguide made of SU8 is cut across by an open trench. The design of the waveguide provides low propagation losses and small divergence of the trapping beam upon emergence from the facet, and the trench designed to be deeper and wider than the optical mode enables full utilization of the optical power with an automatic alignment for counter-propagating beams in a trap volume away from all surfaces. After integration with polydimethylsiloxane (PDMS) microfluidic channel for particle delivery, 0.65 μm and 1 μm diameter polystyrene beads were trapped in free space in the trench, and manipulated to an arbitrary position between the waveguides with a resolution of < 100 nm. Comparison with numerical simulations confirm stable trapping of sub-micron particles, with a 10 kBT threshold power of less than 1 mW and a stiffness that can be 1 order of magnitude larger than that of comparable fiber-based trapping methods.

  19. Fabrication of microfluidic architectures for optimal flow rate and concentration measurement for lab on chip application

    NASA Astrophysics Data System (ADS)

    Adam, Tijjani; Hashim, U.

    2017-03-01

    Optimum flow in micro channel for sensing purpose is challenging. In this study, The optimizations of the fluid sample flows are made through the design and characterization of the novel microfluidics' architectures to achieve the optimal flow rate in the micro channels. The biocompatibility of the Polydimetylsiloxane (Sylgard 184 silicon elastomer) polymer used to fabricate the device offers avenue for the device to be implemented as the universal fluidic delivery system for bio-molecules sensing in various bio-medical applications. The study uses the following methodological approaches, designing a novel microfluidics' architectures by integrating the devices on a single 4 inches silicon substrate, fabricating the designed microfluidic devices using low-cost solution soft lithography technique, characterizing and validating the flow throughput of urine samples in the micro channels by generating pressure gradients through the devices' inlets. The characterization on the urine samples flow in the micro channels have witnessed the constant flow throughout the devices.

  20. An integrated microfluidic chip with 40 MHz lead-free transducer for fluid analysis.

    PubMed

    Lee, S T F; Lam, K H; Lei, L; Zhang, X M; Chan, H L W

    2011-02-01

    The design, fabrication, and evaluation of a high-frequency transducer made from lead-free piezoceramic for the application of microfluidic analysis is described. Barium strontium zirconate titanate [(Ba(0.95)Sr(0.05))(Zr(0.05)Ti(0.95))O(3), abbreviated as BSZT] ceramic has been chosen to be the active element of the transducer. The center frequency and bandwidth of this high-frequency ultrasound transducer have been measured to be 43 MHz and 56.1%, respectively. The transducer was integrated into a microfluidic channel and used to measure the sound velocity and attenuation of the liquid flowing in the channel. Results suggest that lead-free high-frequency transducers could be used for in situ analysis of property of the fluid flowing through the microfluidic system.

  1. Enhanced surface acoustic wave cell sorting by 3D microfluidic-chip design.

    PubMed

    Ung, W L; Mutafopulos, K; Spink, P; Rambach, R W; Franke, T; Weitz, D A

    2017-10-10

    We demonstrate an acoustic wave driven microfluidic cell sorter that combines advantages of multilayer device fabrication with planar surface acoustic wave excitation. We harness the strong vertical component of the refracted acoustic wave to enhance cell actuation by using an asymmetric flow field to increase cell deflection. Precise control of the 3-dimensional flow is realized by topographical structures implemented on the top of the microchannel. We experimentally quantify the effect of the structure dimensions and acoustic parameter. The design attains cell sorting rates and purities approaching those of state of the art fluorescence-activated cell sorters with all the advantages of microfluidic cell sorting.

  2. Protein crystallization using microfluidic technologies based on valves, droplets, and SlipChip.

    PubMed

    Li, Liang; Ismagilov, Rustem F

    2010-01-01

    To obtain protein crystals, researchers must search for conditions in multidimensional chemical space. Empirically, thousands of crystallization experiments are carried out to screen various precipitants at multiple concentrations. Microfluidics can manipulate fluids on a nanoliter scale, and it affects crystallization twofold. First, it miniaturizes the experiments that can currently be done on a larger scale and enables crystallization of proteins that are available only in small amounts. Second, it offers unique experimental approaches that are difficult or impossible to implement on a larger scale. Ongoing development of microfluidic techniques and their integration with protein production, characterization, and in situ diffraction promises to accelerate the progress of structural biology.

  3. Microfluidic chip-based liquid-liquid extraction and preconcentration using a subnanoliter-droplet trapping technique.

    PubMed

    Chen, Hong; Fang, Qun; Yin, Xue-Feng; Fang, Zhao-Lun

    2005-07-01

    A robust and simple approach for microfluidic liquid-liquid (L-L) extraction at the subnanoliter-scale was developed for on-chip sample pretreatment. Organic solvent droplets of a few hundred pL were trapped within micro recesses fabricated in the channel walls of a microfabricated glass chip. L-L extraction was performed by delivering aqueous samples through the channel, with the sample stream continuously flowing adjacent to the droplets. The analytes in aqueous streams were enriched within the droplet with high preconcentration factors owing to both phase transfer and dissolution of organic solvent into the bypassing aqueous sample. An aqueous solution of butyl rhodamine B (BRB) and 1-hexanol were used, respectively, as sample and extractant to demonstrate the performance of the system. The fluorescence intensity of the dye extracted into the droplet was monitored in situ by LIF. The system proved to be an efficient means for achieving high enrichment factors of over 1000, with sample consumption of a few microL. Quantitative measurement of the extracted analyte was achieved with a linear response in the range 1 x 10(-9)-8 x 10(-7) M BRB. The precision of the measured fluorescence values for a 10(-7) M BRB standard with a 12.5 min preconcentration period was 6.6% RSD (n = 5).

  4. A biomimetic microfluidic chip to study the circulation and mechanical retention of red blood cells in the spleen.

    PubMed

    Picot, Julien; Ndour, Papa Alioune; Lefevre, Sophie D; El Nemer, Wassim; Tawfik, Harvey; Galimand, Julie; Da Costa, Lydie; Ribeil, Jean-Antoine; de Montalembert, Mariane; Brousse, Valentine; Le Pioufle, Bruno; Buffet, Pierre; Le Van Kim, Caroline; Français, Olivier

    2015-04-01

    Red blood cells (RBCs) are deformable and flow through vessels narrower than their own size. Their deformability is most stringently challenged when they cross micrometer-wide slits in the spleen. In several inherited or acquired RBC disorders, blockade of small vessels by stiff RBCs can trigger organ damage, but a functional spleen is expected to clear these abnormal RBCs from the circulation before they induce such complications. We analyzed flow behavior of RBCs in a microfluidic chip that replicates the mechanical constraints imposed on RBCs as they cross the human spleen. Polymer microchannels obtained by soft lithography with a hydraulic diameter of 25 μm drove flow into mechanical filtering units where RBCs flew either slowly through 5- to 2-μm-wide slits or rapidly along 10-μm-wide channels, these parallel paths mimicking the splenic microcirculation. Stiff heated RBCs accumulated in narrow slits seven times more frequently than normal RBCs infused simultaneously. Stage-dependent retention of Plasmodium falciparum-infected RBCs was also observed in these slits. We also analyzed RBCs from patients with hereditary spherocytosis and observed retention for those having the most altered mechanical properties as determined by ektacytometry. Thus, in keeping with previous observations in vivo and ex vivo, the chip successfully discriminated poorly deformable RBCs based on their distinct mechanical properties and on the intensity of the cell alteration. Applications to the exploration of the pathogenesis of malaria, hereditary spherocytosis, sickle cell disease and other RBC disorders are envisioned.

  5. ALL-ELECTRONIC DROPLET GENERATION ON-CHIP WITH REAL-TIME FEEDBACK CONTROL FOR EWOD DIGITIAL MICROFLUIDICS

    PubMed Central

    Gong, Jian; Kim, Chang-Jin “CJ”

    2009-01-01

    Electrowetting-on-dielectric (EWOD) actuation enables digital (or droplet) microfluidics where small packets of liquids are manipulated on a two-dimensional surface. Due to its mechanical simplicity and low energy consumption, EWOD holds particular promise for portable systems. To improve volume precision of the droplets, which is desired for quantitative applications such as biochemical assays, existing practices would require near-perfect device fabricaion and operation conditions unless the droplets are generated under feedback control by an extra pump setup off of the chip. In this paper, we develop an all-electronic (i.e., no ancillary pumping) real-time feedback control of on-chip droplet generation. A fast voltage modulation, capacitance sensing, and discrete-time PID feedback controller are integrated on the operating electronic board. A significant improvement is obtained in the droplet volume uniformity, compared with an open loop control as well as the previous feedback control employing an external pump. Furthermore, this new capability empowers users to prescribe the droplet volume even below the previously considered minimum, allowing, for example, 1:x (x < 1) mixing, in comparison to the previously considered n:m mixing (i.e., n and m unit droplets). PMID:18497909

  6. All-electronic droplet generation on-chip with real-time feedback control for EWOD digital microfluidics.

    PubMed

    Gong, Jian; Kim, Chang-Jin C J

    2008-06-01

    Electrowetting-on-dielectric (EWOD) actuation enables digital (or droplet) microfluidics where small packets of liquids are manipulated on a two-dimensional surface. Due to its mechanical simplicity and low energy consumption, EWOD holds particular promise for portable systems. To improve volume precision of the droplets, which is desired for quantitative applications such as biochemical assays, existing practices would require near-perfect device fabrication and operation conditions unless the droplets are generated under feedback control by an extra pump setup off of the chip. In this paper, we develop an all-electronic (i.e., no ancillary pumping) real-time feedback control of on-chip droplet generation. A fast voltage modulation, capacitance sensing, and discrete-time PID feedback controller are integrated on the operating electronic board. A significant improvement is obtained in the droplet volume uniformity, compared with an open loop control as well as the previous feedback control employing an external pump. Furthermore, this new capability empowers users to prescribe the droplet volume even below the previously considered minimum, allowing, for example, 1 : x (x < 1) mixing, in comparison to the previously considered n : m mixing (i.e., n and m unit droplets).

  7. A Microfluidic ExoSearch Chip for Multiplexed Exosome Detection Towards Blood-based Ovarian Cancer Diagnosis†

    PubMed Central

    Zhao, Zheng; Yang, Yang; Zeng, Yong; He, Mei

    2015-01-01

    Tumor-derived circulating exosomes, enriched with a group of tumor antigens, have been recognized as a promising biomarker source for cancer diagnosis via less invasive procedure. Quantitatively pinpointing exosome tumor markers is appealing, yet challenging. In this study, we developed a simple microfluidic approach (ExoSearch) which provides enriched preparation of blood plasma exosomes for in-situ, multiplexed detection using immunomagnetic beads. The ExosSearch chip offers robust, continuous-flow design for quantitative isolation and release of blood plasma exosomes in a wide range of preparation volumes (10 μL to 10 mL). We employed the ExoSearch chip for blood-based diagnosis of ovarian cancer by multiplexed measurement of three exosomal tumor markers (CA-125, EpCAM, CD24) using a training set of ovarian cancer patient plasma, which showed significant diagnostic power (a.u.c. = 1.0, p = 0.001) and was comparable with standard Bradford assay. This work provides an essentially needed platform for utilization of exosomes in clinical cancer diagnosis, as well as fundamental exosome research. PMID:26645590

  8. Cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode as electrochemical sensor on microfluidic chip.

    PubMed

    Li, Xinchun; Chen, Zuanguang; Zhong, Yuwen; Yang, Fan; Pan, Jianbin; Liang, Yajing

    2012-01-13

    Nanomaterial-based electrochemical sensor has received significant interest. In this work, cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode was electrochemically prepared and exploited as an amperometric detector for microchip electrophoresis. The prepared sensor displayed rapid and sensitive response towards hydrazine and isoniazid oxidation, which was attributed to synergetic electrocatalytic effect of cobalt hexacyanoferrate and multi-walled carbon nanotubes. The sensitivity enhancement with nearly two orders of magnitude was gained, compared with the bare carbon paste electrode, with the detection limit of 0.91 μM (S/N=3) for hydrazine. Acceptable repeatability of the microanalysis system was verified by consecutive eleven injections of hydrazine without chip and electrode treatments, the RSDs for peak current and migration time were 3.4% and 2.1%, respectively. Meanwhile, well-shaped electrophoretic peaks were observed, mainly due to fast electron transfer of electroactive species on the modified electrode. The developed microchip-electrochemistry setup was successfully applied to the determination of hydrazine and isoniazid in river water and pharmaceutical preparation, respectively. Several merits of the novel electrochemical sensor coupled with microfluidic platform, such as comparative stability, easy fabrication and high sensitivity, hold great potential for hydrazine compounds assay in the lab-on-a-chip system. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Hands-off preparation of monodisperse emulsion droplets using a poly(dimethylsiloxane) microfluidic chip for droplet digital PCR.

    PubMed

    Tanaka, Hironari; Yamamoto, Shunsuke; Nakamura, Arichika; Nakashoji, Yuta; Okura, Naoaki; Nakamoto, Norimitsu; Tsukagoshi, Kazuhiko; Hashimoto, Masahiko

    2015-04-21

    A fully autonomous method of creating highly monodispersed emulsion droplets with a low sample dead volume was realized using a degassed poly(dimethylsiloxane) (PDMS) microfluidic chip possessing a simple T-junction channel geometry with two inlet reservoirs for oil and water to be loaded and one outlet reservoir for the collection of generated droplets. Autonomous transport of oil and water phases in the channel was executed by permeation of air confined inside the outlet reservoir into the degassed PDMS. The only operation required for droplet creation was simple pipetting of oil and aqueous solutions into the inlet reservoirs. Long-lasting fluid transport in the current system enabled us to create ca. 51,000 monodispersed droplets (with a coefficient of variation of <3% for the droplet diameter) in 80 min with a maximum droplet generation rate of ca. 12 Hz using a PDMS chip that had been degassed overnight. With multiple time-course measurements, the reproducibility in the current method of droplet preparation was confirmed, with tunable droplet sizes achieved simply by changing the cross-sectional dimensions of the microchannel. Furthermore, it was verified that the resultant droplets could serve as microreactors for digital polymerase chain reactions. This hands-free technique for preparing monodispersed droplets in a very facile and inexpensive fashion is intended for, but not limited to, bioanalytical applications and is also applicable to material syntheses.

  10. Microfluidics Integrated Biosensors: A Leading Technology towards Lab-on-a-Chip and Sensing Applications

    PubMed Central

    Luka, George; Ahmadi, Ali; Najjaran, Homayoun; Alocilja, Evangelyn; DeRosa, Maria; Wolthers, Kirsten; Malki, Ahmed; Aziz, Hassan; Althani, Asmaa; Hoorfar, Mina

    2015-01-01

    A biosensor can be defined as a compact analytical device or unit incorporating a biological or biologically derived sensitive recognition element immobilized on a physicochemical transducer to measure one or more analytes. Microfluidic systems, on the other hand, provide throughput processing, enhance transport for controlling the flow conditions, increase the mixing rate of different reagents, reduce sample and reagents volume (down to nanoliter), increase sensitivity of detection, and utilize the same platform for both sample preparation and detection. In view of these advantages, the integration of microfluidic and biosensor technologies provides the ability to merge chemical and biological components into a single platform and offers new opportunities for future biosensing applications including portability, disposability, real-time detection, unprecedented accuracies, and simultaneous analysis of different analytes in a single device. This review aims at representing advances and achievements in the field of microfluidic-based biosensing. The review also presents examples extracted from the literature to demonstrate the advantages of merging microfluidic and biosensing technologies and illustrate the versatility that such integration promises in the future biosensing for emerging areas of biological engineering, biomedical studies, point-of-care diagnostics, environmental monitoring, and precision agriculture. PMID:26633409

  11. Artificial photosynthesis on a chip: microfluidic cofactor regeneration and photoenzymatic synthesis under visible light.

    PubMed

    Lee, Joon Seok; Lee, Sahng Ha; Kim, Jae Hong; Park, Chan Beum

    2011-07-21

    We present a microfluidic artificial photosynthetic platform that incorporates quantum dots and redox enzymes for photoenzymatic synthesis of fine chemicals under visible light. Similar to natural photosynthesis, photochemical cofactor regeneration takes place in the light-dependent reaction zone, which is then coupled with the light-independent, enzymatic synthesis in the downstream of the microchannel.

  12. Application of microfluidic chip with integrated optics for electrophoretic separations of proteins.

    PubMed

    Vieillard, Julien; Mazurczyk, Radoslaw; Morin, Christophe; Hannes, Benjamin; Chevolot, Yann; Desbène, Paul-Louis; Krawczyk, Stanislas

    2007-01-15

    This paper describes the fabrication, the characterization and the applications of a capillary electrophoresis microchip. This hybrid device (glass/PDMS) features channels and optical waveguides integrated in one common substrate. It can be used for electrophoretic separation and fluorimetric detection of molecules. The microfluidic performance of the device is demonstrated by capillary zone and gel electrophoresis of proteins.

  13. Development and Fabrication of Nanoporous Silicon-based Bioreactors within a Microfluidic Chip

    SciTech Connect

    Siuti, Piro; Choi, Chang Kyoung; Doktycz, Mitchel John; Retterer, Scott T

    2010-01-01

    Multi-scale lithography and cryogenic deep reactive ion etching techniques were used to create ensembles of nanoporous, picoliter volume, reaction vessels within a microfluidic system. The fabrication of these vessels is described and how this process can be used to tailor vessel porosity by controlling the width of slits that constitute the vessel pores is demonstrated. Control of pore size allows the containment of nucleic acids and enzymes that are the foundation of biochemical reaction systems, while allowing smaller reaction constituents to traverse the container membrane and continuously supply the reaction. In this work, a 5.4kB DNA plasmid was retained within the reaction vessels and labeled under microfluidic control with ethidium bromide as an initial proof-of-principle. Subsequently, a coupled enzyme reaction, in which glucose oxidase and horseradish peroxidase were contained and fed with a substrate solution of glucose and Amplex Red to produce fluorescent Resorufin, was carried out under microfluidic control and monitored using fluorescent microscopy. The fabrication techniques presented are broadly applicable and can be adapted to produce devices in which a variety of high aspect ratio, nanoporous silicon structures can be integrated within a microfluidic network. The devices shown here are amenable to being scaled in number and organized to implement more complex reaction systems for applications in sensing and production of biologically based therapeutics as well as fundamental studies of biological reaction systems.

  14. Development and fabrication of nanoporous silicon-based bioreactors within a microfluidic chip.

    PubMed

    Retterer, Scott T; Siuti, Piro; Choi, Chang-Kyoung; Thomas, Darrell K; Doktycz, Mitchel J

    2010-05-07

    Multi-scale lithography and cryogenic deep reactive ion etching techniques were used to create ensembles of nanoporous, picolitre volume, reaction vessels within a microfluidic system. The fabrication of these vessels is described and how this process can be used to tailor vessel porosity by controlling the width of slits that constitute the vessel pores is demonstrated. Control of pore size allows the containment of nucleic acids and enzymes that are the foundation of biochemical reaction systems, while allowing smaller reaction constituents to traverse the container membrane and continuously supply the reaction. In this work, a 5.4 kb DNA plasmid was retained within the reaction vessels and labeled under microfluidic control with ethidium bromide as an initial proof-of-principle. Subsequently, a coupled enzyme reaction, in which glucose oxidase (GOX) and horseradish peroxidase (HRP) were contained and fed with a substrate solution of glucose and Amplex Red to produce fluorescent resorufin, was carried out under microfluidic control and monitored using fluorescent microscopy. The fabrication techniques presented are broadly applicable and can be adapted to produce devices in which a variety of high aspect ratio, nanoporous silicon structures can be integrated within a microfluidic network. The devices shown here are amenable to being scaled in number and organized to implement more complex reaction systems for applications in sensing and actuation as well as fundamental studies of biological reaction systems.

  15. Microfluidics Integrated Biosensors: A Leading Technology towards Lab-on-a-Chip and Sensing Applications.

    PubMed

    Luka, George; Ahmadi, Ali; Najjaran, Homayoun; Alocilja, Evangelyn; DeRosa, Maria; Wolthers, Kirsten; Malki, Ahmed; Aziz, Hassan; Althani, Asmaa; Hoorfar, Mina

    2015-12-01

    A biosensor can be defined as a compact analytical device or unit incorporating a biological or biologically derived sensitive recognition element immobilized on a physicochemical transducer to measure one or more analytes. Microfluidic systems, on the other hand, provide throughput processing, enhance transport for controlling the flow conditions, increase the mixing rate of different reagents, reduce sample and reagents volume (down to nanoliter), increase sensitivity of detection, and utilize the same platform for both sample preparation and detection. In view of these advantages, the integration of microfluidic and biosensor technologies provides the ability to merge chemical and biological components into a single platform and offers new opportunities for future biosensing applications including portability, disposability, real-time detection, unprecedented accuracies, and simultaneous analysis of different analytes in a single device. This review aims at representing advances and achievements in the field of microfluidic-based biosensing. The review also presents examples extracted from the literature to demonstrate the advantages of merging microfluidic and biosensing technologies and illustrate the versatility that such integration promises in the future biosensing for emerging areas of biological engineering, biomedical studies, point-of-care diagnostics, environmental monitoring, and precision agriculture.

  16. Microfluidic selection and retention of a single cardiac myocyte, on-chip dye loading, cell contraction by chemical stimulation, and quantitative fluorescent analysis of intracellular calcium.

    PubMed

    Li, Xiujun; Li, Paul C H

    2005-07-15

    A microfluidic method to study the contraction of a single cardiac myocyte (heart muscle cell) has been developed. This method integrates various single-cell operations as well as on-chip dye loading, and quantitative analysis of intracellular calcium concentration, [Ca2+]i. After the channel enlargement by on-chip etching to accommodate large-sized cardiac myocytes, a single cell is selected and retained at a V-shaped cell retention structure within the microchip. Owing to the fragile property of the cardiac myocytes that could easily be damaged by centrifugation, the calcium-sensitive fluorescent dye was loaded in the cell by on-chip dye loading. This on-chip method minimized the damage to the cells from the use of a centrifuge in the conventional method and provided a way of cellular analysis of fragile cells. Subsequently, quantitative analysis of [Ca2+]i of a single cardiac myocyte by fluorescence measurement was achieved for the first time in a microfluidic chip, thanks to the intracellular calcium stimulant of ionomycin. The resting [Ca2+]i of the cardiomyocyte determined was consistent with the literature value. From the spontaneous contraction study, it was found that fluorescence intensity cannot represent the [Ca2+]i variation accurately, which implied the importance of the quantitative analysis of [Ca2+]i.

  17. Real-time monitoring of intracellular calcium dynamic mobilization of a single cardiomyocyte in a microfluidic chip pertaining to drug discovery.

    PubMed

    Li, Xiujun; Huang, Jingbo; Tibbits, Glen F; Li, Paul C H

    2007-12-01

    A microfluidic method for real-time quantitative measurement of cellular response pertaining to drug discovery is reported. This method is capable of multiple-step liquid delivery for measuring the drug response of a single cardiomyocyte, due to the improved cell retention by a newly designed chip. The chip, which consists of a cell-retention chamber with a weir structure, was fabricated just by a one-photomask microfabrication procedure followed by on-chip etching. This method differs from the conventional method, which uses two-mask photolithography to fabricate the microchannel (deep etch) and the weir structure (shallow etch). The dimensions of the weir structure have been predicted by a mathematical model, and confirmed by confocal microscopy. Using this microfluidic method, the dynamic [Ca2+]i mobilization in a single cardiomyocyte during its spontaneous contraction was quantified. Furthermore, we measured the cellular response of a cardiomyocyte on (i) a known cardiotonic agent (caffeine), (ii) a cardiotoxic chemotherapeutic drug (daunorubicin), and (iii) an herbal anticancer drug candidate - isoliquiritigenin (IQ) based on the fluorescent calcium measurement. It was found that IQ had produced a less pronounced effect on calcium mobilization( )of the cardiomyocytes whereas caffeine and daunorubicin had much stronger effects on the cells. These three experiments on cardiomyocytes pertaining to drug discovery were only possible after the improved cell retention provided by the new chip design (MV2) required for multiple-step real-time cellular analysis on a microchip, as compared with our old chip design (MV1).

  18. Design and Construction of a Multi-Organ Microfluidic Chip Mimicking the in vivo Microenvironment of Lung Cancer Metastasis.

    PubMed

    Xu, Zhiyun; Li, Encheng; Guo, Zhe; Yu, Ruofei; Hao, Hualong; Xu, Yitong; Sun, Zhao; Li, Xiancheng; Lyu, Jianxin; Wang, Qi

    2016-10-05

    Metastasis is a complex pathophysiological process. As the main cause of cancer mortality in humans it represents a serious challenge to both basic researchers and clinicians. Here we report the design and construction of a multi-organ microfluidic chip that closely mimics the in vivo microenvironment of lung cancer metastasis. This multi-organs-on-a-chip includes an upstream "lung" and three downstream "distant organs", with three polydimethylsiloxane (PDMS) layers and two thin PDMS microporous membranes bonded to form three parallel microchannels. Bronchial epithelial, lung cancer, microvascular endothelial, mononuclear, and fibroblast cells were grown separated by the biomembrane in upstream "lung", while astrocytes, osteocytes, and hepatocytes were grown in distant chambers, to mimic lung cancer cell metastasis to the brain, bone, and liver. After culture in this system, lung cancer cells formed a "tumor mass", showed epithelial-mesenchymal transition (with altered expression of E-cadherin, N-cadherin, Snail1, and Snail2) and invasive capacity. A549 cells co-cultured with astrocytes overexpressed CXCR4 protein, indicating damage of astrocytes after cancer cell metastasis to the brain. Osteocytes overexpressed RANKL protein indicates damage of osteocytes after cancer cell metastasis to the bone, and hepatocytes overexpressed AFP protein indicates damage to hepatocytes after cancer cell metastasis to the liver. Finally, in vivo imaging of cancer growth and metastasis in a nude mice model validated the performance of metastasis in the organs-on-chip system. This system provides a useful tool to mimic the in vivo microenvironment of cancer metastasis and to investigate cell-cell interactions during metastasis.

  19. Evaluation of a microfluidic chip system for preparation of bacterial DNA from swabs, air, and surface water samples.

    PubMed

    Julich, Sandra; Hotzel, Helmut; Gärtner, Claudia; Trouchet, Daniel; Fawzy El Metwaly Ahmed, Marwa; Kemper, Nicole; Tomaso, Herbert

    2016-11-01

    The detection of bacterial pathogens from complex sample matrices by PCR requires efficient DNA extraction. In this study, a protocol for extraction and purification of DNA from swabs, air, and water samples using a microfluidic chip system was established. The optimized protocol includes a combination of thermal, chemical and enzymatic lysis followed by chip-based DNA purification using magnetic particles. The procedure was tested using Gram-positive Bacillus thuringiensis Berliner var. kurstaki as a model organism for Bacillus anthracis and the attenuated live vaccine strain of Francisella tularensis subsp. holarctica as Gram-negative bacterium. The detection limits corresponded to 10(3) genome equivalents per milliliter (GE/ml) for surface water samples spiked with F. tularensis and 10(2) GE/ml for B. thuringiensis. In air, 10 GE of F. tularensis per 10 L and 1 GE of B. thuringiensis per 10 L were detectable. For swab samples obtained from artificially contaminated surfaces the detection limits were 4 × 10(3) GE/cm(2) for F. tularensis and 4 × 10(2) GE/cm(2) for B. thuringiensis. Suitability of the chip-assisted procedure for DNA preparation of real samples was demonstrated using livestock samples. The presence of thermophilic Campylobacter spp. DNA could be confirmed in air samples collected on pig and broiler farms. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  20. High-throughput nanoliter sample introduction microfluidic chip-based flow injection analysis system with gravity-driven flows.

    PubMed

    Du, Wen-Bin; Fang, Qun; He, Qiao-Hong; Fang, Zhao-Lun

    2005-03-01

    In this work, a simple, robust, and automated microfluidic chip-based FIA system with gravity-driven flows and liquid-core waveguide (LCW) spectrometric detection was developed. The high-throughput sample introduction system was composed of a capillary sampling probe and an array of horizontally positioned microsample vials with a slot fabricated on the bottom of each vial. FI sample loading and injection were performed by linearly moving the array of vials filled alternately with 50-microL samples and carrier, allowing the probe inlet to enter the solutions in the vials through the slots sequentially and the sample and carrier solution to be introduced into the chip driven by gravity. The performance of the system was demonstrated using the complexation of o-phenanthroline with Fe(II) as a model reaction. A 20-mm-long Teflon AF 2400 capillary (50-microm i.d., 375-microm o.d.) was connected to the chip to function as a LCW detection flow cell with a cell volume of 40 nL and effective path length of 1.7 cm. Linear absorbance response was obtained in the range of 1.0-100 microM Fe(II) (r2=0.9967), and a good reproducibility of 0.6% RSD (n=18) was achieved. The sensitivity was comparable with that obtained using conventional FIA systems, which typically consume 10,000-fold more sample. The highest sampling throughput of 1000 h-1 was obtained by using injection times of 0.08 and 3.4 s for sample and carrier solution, respectively, with a sample consumption of only 0.6 nL for each cycle.

  1. Continual exposure to cigarette smoke extracts induces tumor-like transformation of human nontumor bronchial epithelial cells in a microfluidic chip.

    PubMed

    Li, Encheng; Xu, Zhiyun; Liu, Fen; Wang, Huiling; Wen, Jiabin; Shao, Shujuan; Zhang, Lichuan; Wang, Lei; Liu, Chong; Lu, Jianxin; Wang, Wenxin; Gao, Zhancheng; Wang, Qi

    2014-08-01

    Heavy cigarette smoking-related chronic obstructive pulmonary disease is an independent risk factor for lung squamous carcinoma. However, the mechanisms underlying the malignant transformation of bronchial epithelial cells are unclear. In our study, human tumor-adjacent bronchial epithelial cells were obtained from 10 cases with smoking-related chronic obstructive pulmonary disease and lung squamous carcinoma and cultured in an established microfluidic chip for continual exposure to cigarette smoke extracts (CSE) to investigate the potential tumor-like transformation and mechanisms. The integrated microfluidic chip included upstream concentration gradient generator and downstream cell culture chambers supplied by flowing medium containing different concentrations of CSE. Our results showed that continual exposure to low doses of CSE promoted cell proliferation whereas to high doses of CSE triggered cell apoptosis. Continual exposure to CSE promoted reactive oxygen species production in human epithelial cells in a dose-dependent manner. More importantly, continual exposure to low dose of CSE promoted the epithelial-to-mesenchymal transition process and anchorage-independent growth, and increased chromosome instability in bronchial epithelial cells, accompanied by activating the GRP78, NF-κB, and PI3K pathways. The established microfluidic chip is suitable for primary culture of human tumor-adjacent bronchial epithelial cells to investigate the malignant transformation. Continual exposure to low doses of CSE promoted tumor-like transformation of human nontumor bronchial epithelial cells by inducing reactive oxygen species production and activating the relevant signaling.

  2. Crack-free direct-writing on glass using a low-power UV laser in the manufacture of a microfluidic chip

    NASA Astrophysics Data System (ADS)

    Cheng, Ji-Yen; Yen, Meng-Hua; Wei, Cheng-Wey; Chuang, Yung-Chuan; Young, Tai-Horng

    2005-06-01

    Glass is an excellent material for use as a microfluidic chip substrate because it has great chemical and thermal stability. This work describes a flexible platform for the rapid prototyping of microfluidic chips fabricated from glass. A debris-free laser direct-writing technology that requires no photomask generation is developed. A 266 nm laser with a high repetition rate is employed in laser-induced backside wet etching (LIBWE) for glass machining. A microfluidic pattern is designed using computer drawing software and then automatically translated into computer numerical control motion so that the microtrench is directly fabricated on the glass chip. The overall machining speed can be increased by increasing the repetition rate to ~6 kHz. Without a clean room facility or the highly corrosive acid, HF, the overall development time is within hours. Trenches with complex structures that are hard to fabricate by photolithography were easily produced by laser direct-writing. An integrated microreactor/concentrator is demonstrated. The crack-free and debris-free surface was characterized by SEM and a surface profiler. Various effective etching chemicals for the LIBWE process were investigated to understand the etching mechanism. The minimal laser power used for glass etching was approximately 20 mW for a 6 µm wide microtrench. Several new compounds have been demonstrated to be effective in ablation. The etch threshold is minimum and does not decrease further as the unit length absorbance increases above 8000 in acetone solution.

  3. Detection of K-ras oncogene from the human genomic DNA using ultrasonication and a quantum dots-based microfluidic chip.

    PubMed

    Noh, Han Na; Kim, Jong Sung

    2013-09-01

    In clinical diagnostics, single-stranded DNAs (ssDNA) have been prepared from the human genomic DNA for the detection of a specific gene. In this study, the human genomic DNA was degraded via ultrasonication in solution, and K-ras oncogene was detected from the DNA fragments via the fluorescence quenching of quantum dots (QDs) by intercalating dyes after hybridization of the target, to probe DNAs in a microfluidic chip. K-ras is one of the most activated common oncogenes, and many human tumors are known to be due to the mutation of this gene. QDs are nano-sized semiconductors with a wide selection of emission wavelengths and exceptional stability against photo bleaching. In this study, probe DNA-conjugated QDs were immobilized to polystyrene microbeads, and the DNA-microbead-QDs complexes were packed through a microchannel by pillars that trap the beads in the microfluidic chip. The fluorescence of the QDs could be quenched by intercalating dye (TOTO-3) after hybridization of K-ras oncogene to the probe DNA in the channel. The fluorescence intensity decrease of the QDs can be used as an indication of the K-ras oncogene. By introducing an alkaline buffer solution, the DNAs were denatured, and the fluorescence intensity of the QDs again increased, which shows the possibility of reuse of the microfluidic chip for the detection of the K-ras gene.

  4. Retina-on-a-chip: a microfluidic platform for point access signaling studies

    PubMed Central

    Dodson, Kirsten H.; Echevarria, Franklin D.; Li, Deyu; Sappington, Rebecca M.; Edd, Jon F.

    2016-01-01

    We report on a microfluidic platform for culture of whole organs or tissue slices with the capability of point access reagent delivery to probe the transport of signaling events. Whole mice retina were maintained for multiple days with negative pressure applied to tightly but gently bind the bottom of the retina to a thin poly-(dimethylsiloxane) membrane, through which twelve 100 μm diameter through-holes served as fluidic access points. Staining with toluidine blue, transport of locally applied cholera toxin beta, and transient response to lipopolysaccharide in the retina demonstrated the capability of the microfluidic platform. The point access fluidic delivery capability could enable new assays in the study of various kinds of excised tissues, including retina. PMID:26559199

  5. Diode laser bonding of planar microfluidic devices, MOEMS, bioMEMS, diagnostic chips, and microarrays

    NASA Astrophysics Data System (ADS)

    Chen, Jie-Wei; Zybko, Jerry M.

    2005-01-01

    The assembly of plastic microfluidic devices, MOEMS and microarrays requiring high positioning and welding accuracy in the micrometer range, has been successfully achieved using a new technology based on laser transmission welding combined with a photolithographic mask technique. This paper reviews a laser assembly platform for the joining of microfluidic plastic parts with its main related process characteristics and its potential for low-cost and high volume manufacturing. The system consists of a of diode laser with a mask and an automated alignment function to generate micro welding seams with freely definable geometries. A fully automated mask alignment system with a resolution of < 2 &mum and a precise, noncontact energy input allows a fast welding of micro structured plastic parts with high reproducibility and excellent welding quality.

  6. World-to-chip interconnects for efficient loading of genomic DNA into microfluidic channels

    NASA Astrophysics Data System (ADS)

    Humphreys, Tim; Andersson, Johan; Södervall, Ulf;