A Combined Fabrication and Instrumentation Platform for Sample Preparation.

PubMed

Guckenberger, David J; Thomas, Peter C; Rothbauer, Jacob; LaVanway, Alex J; Anderson, Meghan; Gilson, Dan; Fawcett, Kevin; Berto, Tristan; Barrett, Kevin; Beebe, David J; Berry, Scott M

2014-06-01

While potentially powerful, access to molecular diagnostics is substantially limited in the developing world. Here we present an approach to reduced cost molecular diagnostic instrumentation that has the potential to empower developing world communities by reducing costs through streamlining the sample preparation process. In addition, this instrument is capable of producing its own consumable devices on demand, reducing reliance on assay suppliers. Furthermore, this instrument is designed with an "open" architecture, allowing users to visually observe the assay process and make modifications as necessary (as opposed to traditional "black box" systems). This open environment enables integration of microfluidic fabrication and viral RNA purification onto an easy-to-use modular system via the use of interchangeable trays. Here we employ this system to develop a protocol to fabricate microfluidic devices and then use these devices to isolate viral RNA from serum for the measurement of human immunodeficiency virus (HIV) viral load. Results obtained from this method show significantly reduced error compared with similar nonautomated sample preparation processes. © 2014 Society for Laboratory Automation and Screening.

Actuation of digital micro drops by electrowetting on open microfluidic chips fabricated in photolithography.

PubMed

Ko, Hyojin; Lee, Jeong Soo; Jung, Chan-Hee; Choi, Jae-Hak; Kwon, Oh-Sun; Shin, Kwanwoo

2014-08-01

Basic manipulations of discrete liquid drops on opened microfluidic chips based on electrowetting on dielectrics were described. While most developed microfluidic chips are closed systems equipped with a top plate to cover mechanically and to contact electrically to drop samples, our chips are opened systems with a single plate without any electric contact to drops directly. The chips consist of a linear array of patterned electrodes at 1.8 mm pitch was fabricated on a glass plate coated with thin hydrophobic and dielectric layers by using various methods including photolithography, spin coating and ion sputtering. Several actuations such as lateral oscillation, colliding mergence and translational motion for 3-10 μL water drops have been demonstrated satisfactory. All these kinetic performances of opened chips were similar to those of closed chip systems, indicating superiority of a none-contact method for the transport of drops on opened microfluidic chips actuated by using electrowetting technique.

Lab-on-CMOS Integration of Microfluidics and Electrochemical Sensors

PubMed Central

Huang, Yue; Mason, Andrew J.

2013-01-01

This paper introduces a CMOS-microfluidics integration scheme for electrochemical microsystems. A CMOS chip was embedded into a micro-machined silicon carrier. By leveling the CMOS chip and carrier surface to within 100 nm, an expanded obstacle-free surface suitable for photolithography was achieved. Thin film metal planar interconnects were microfabricated to bridge CMOS pads to the perimeter of the carrier, leaving a flat and smooth surface for integrating microfluidic structures. A model device containing SU-8 microfluidic mixers and detection channels crossing over microelectrodes on a CMOS integrated circuit was constructed using the chip-carrier assembly scheme. Functional integrity of microfluidic structures and on-CMOS electrodes was verified by a simultaneous sample dilution and electrochemical detection experiment within multi-channel microfluidics. This lab-on-CMOS integration process is capable of high packing density, is suitable for wafer-level batch production, and opens new opportunities to combine the performance benefits of on-CMOS sensors with lab-on-chip platforms. PMID:23939616

Lab-on-CMOS integration of microfluidics and electrochemical sensors.

PubMed

Huang, Yue; Mason, Andrew J

2013-10-07

This paper introduces a CMOS-microfluidics integration scheme for electrochemical microsystems. A CMOS chip was embedded into a micro-machined silicon carrier. By leveling the CMOS chip and carrier surface to within 100 nm, an expanded obstacle-free surface suitable for photolithography was achieved. Thin film metal planar interconnects were microfabricated to bridge CMOS pads to the perimeter of the carrier, leaving a flat and smooth surface for integrating microfluidic structures. A model device containing SU-8 microfluidic mixers and detection channels crossing over microelectrodes on a CMOS integrated circuit was constructed using the chip-carrier assembly scheme. Functional integrity of microfluidic structures and on-CMOS electrodes was verified by a simultaneous sample dilution and electrochemical detection experiment within multi-channel microfluidics. This lab-on-CMOS integration process is capable of high packing density, is suitable for wafer-level batch production, and opens new opportunities to combine the performance benefits of on-CMOS sensors with lab-on-chip platforms.

Transient deformation of a droplet near a microfluidic constriction: A quantitative analysis

NASA Astrophysics Data System (ADS)

Trégouët, Corentin; Salez, Thomas; Monteux, Cécile; Reyssat, Mathilde

2018-05-01

We report on experiments that consist of deforming a collection of monodisperse droplets produced by a microfluidic chip through a flow-focusing device. We show that a proper numerical modeling of the flow is necessary to access the stress applied by the latter on the droplet along its trajectory through the chip. This crucial step enables the full integration of the differential equation governing the dynamical deformation, and consequently the robust measurement of the interfacial tension by fitting the experiments with the calculated deformation. Our study thus demonstrates the feasibility of quantitative in situ rheology in microfluidic flows involving, e.g., droplets, capsules, or cells.

Simple and Versatile 3D Printed Microfluidics Using Fused Filament Fabrication.

PubMed

Morgan, Alex J L; Hidalgo San Jose, Lorena; Jamieson, William D; Wymant, Jennifer M; Song, Bing; Stephens, Phil; Barrow, David A; Castell, Oliver K

2016-01-01

The uptake of microfluidics by the wider scientific community has been limited by the fabrication barrier created by the skills and equipment required for the production of traditional microfluidic devices. Here we present simple 3D printed microfluidic devices using an inexpensive and readily accessible printer with commercially available printer materials. We demonstrate that previously reported limitations of transparency and fidelity have been overcome, whilst devices capable of operating at pressures in excess of 2000 kPa illustrate that leakage issues have also been resolved. The utility of the 3D printed microfluidic devices is illustrated by encapsulating dental pulp stem cells within alginate droplets; cell viability assays show the vast majority of cells remain live, and device transparency is sufficient for single cell imaging. The accessibility of these devices is further enhanced through fabrication of integrated ports and by the introduction of a Lego®-like modular system facilitating rapid prototyping whilst offering the potential for novices to build microfluidic systems from a database of microfluidic components.

Simple and Versatile 3D Printed Microfluidics Using Fused Filament Fabrication

PubMed Central

Morgan, Alex J. L.; Hidalgo San Jose, Lorena; Jamieson, William D.; Wymant, Jennifer M.; Song, Bing; Stephens, Phil

2016-01-01

The uptake of microfluidics by the wider scientific community has been limited by the fabrication barrier created by the skills and equipment required for the production of traditional microfluidic devices. Here we present simple 3D printed microfluidic devices using an inexpensive and readily accessible printer with commercially available printer materials. We demonstrate that previously reported limitations of transparency and fidelity have been overcome, whilst devices capable of operating at pressures in excess of 2000 kPa illustrate that leakage issues have also been resolved. The utility of the 3D printed microfluidic devices is illustrated by encapsulating dental pulp stem cells within alginate droplets; cell viability assays show the vast majority of cells remain live, and device transparency is sufficient for single cell imaging. The accessibility of these devices is further enhanced through fabrication of integrated ports and by the introduction of a Lego®-like modular system facilitating rapid prototyping whilst offering the potential for novices to build microfluidic systems from a database of microfluidic components. PMID:27050661

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

PubMed

Yang, Zhen; Maeda, Ryutaro

2002-10-01

We report a prototype for a standard connector between a microfluidic chip and the macroworld. 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 systems efficiently.

Soft Lithographic Procedure for Producing Plastic Microfluidic Devices with View-ports Transparent to Visible and Infrared Light.

PubMed

Suryana, Mona; Shanmugarajah, Jegan V; Maniam, Sivakumar M; Grenci, Gianluca

2017-08-17

Infrared (IR) spectro-microscopy of living biological samples is hampered by the absorption of water in the mid-IR range and by the lack of suitable microfluidic devices. Here, a protocol for the fabrication of plastic microfluidic devices is demonstrated, where soft lithographic techniques are used to embed transparent Calcium Fluoride (CaF2) view-ports in connection with observation chamber(s). The method is based on a replica casting approach, where a polydimethylsiloxane (PDMS) mold is produced through standard lithographic procedures and then used as the template to produce a plastic device. The plastic device features ultraviolet/visible/infrared (UV/Vis/IR) -transparent windows made of CaF2 to allow for direct observation with visible and IR light. The advantages of the proposed method include: a reduced need for accessing a clean room micro-fabrication facility, multiple view-ports, an easy and versatile connection to an external pumping system through the plastic body, flexibility of the design, e.g., open/closed channels configuration, and the possibility to add sophisticated features such as nanoporous membranes.

Incorporation of prefabricated screw, pneumatic, and solenoid valves into microfluidic devices

PubMed Central

Hulme, S. Elizabeth; Shevkoplyas, Sergey S.

2011-01-01

This paper describes a method for prefabricating screw, pneumatic, and solenoid valves and embedding them in microfluidic devices. This method of prefabrication and embedding is simple, requires no advanced fabrication, and is compatible with soft lithography. Because prefabrication allows many identical valves to be made at one time, the performance across different valves made in the same manner is reproducible. In addition, the performance of a single valve is reproducible over many cycles of opening and closing: an embedded solenoid valve opened and closed a microfluidic channel more than 100,000 times with no apparent deterioration in its function. It was possible to combine all three types of prefabricated valves in a single microfluidic device to control chemical gradients in a microfluidic channel temporally and spatially. PMID:19209338

Incorporation of prefabricated screw, pneumatic, and solenoid valves into microfluidic devices.

PubMed

Hulme, S Elizabeth; Shevkoplyas, Sergey S; Whitesides, George M

2009-01-07

This paper describes a method for prefabricating screw, pneumatic, and solenoid valves and embedding them in microfluidic devices. This method of prefabrication and embedding is simple, requires no advanced fabrication, and is compatible with soft lithography. Because prefabrication allows many identical valves to be made at one time, the performance across different valves made in the same manner is reproducible. In addition, the performance of a single valve is reproducible over many cycles of opening and closing: an embedded solenoid valve opened and closed a microfluidic channel more than 100,000 times with no apparent deterioration in its function. It was possible to combine all three types of prefabricated valves in a single microfluidic device to control chemical gradients in a microfluidic channel temporally and spatially.

Droplet-based microfluidic analysis and screening of single plant cells.

PubMed

Yu, Ziyi; Boehm, Christian R; Hibberd, Julian M; Abell, Chris; Haseloff, Jim; Burgess, Steven J; Reyna-Llorens, Ivan

2018-01-01

Droplet-based microfluidics has been used to facilitate high-throughput analysis of individual prokaryote and mammalian cells. However, there is a scarcity of similar workflows applicable to rapid phenotyping of plant systems where phenotyping analyses typically are time-consuming and low-throughput. We report on-chip encapsulation and analysis of protoplasts isolated from the emergent plant model Marchantia polymorpha at processing rates of >100,000 cells per hour. We use our microfluidic system to quantify the stochastic properties of a heat-inducible promoter across a population of transgenic protoplasts to demonstrate its potential for assessing gene expression activity in response to environmental conditions. We further demonstrate on-chip sorting of droplets containing YFP-expressing protoplasts from wild type cells using dielectrophoresis force. This work opens the door to droplet-based microfluidic analysis of plant cells for applications ranging from high-throughput characterisation of DNA parts to single-cell genomics to selection of rare plant phenotypes.

Micro-fluidic interconnect

DOEpatents

Okandan, Murat [Albuquerque, NM; Galambos, Paul C [Albuquerque, NM; Benavides, Gilbert L [Los Ranchos, NM; Hetherington, Dale L [Albuquerque, NM

2006-02-28

An apparatus for simultaneously aligning and interconnecting microfluidic ports is presented. Such interconnections are required to utilize microfluidic devices fabricated in Micro-Electromechanical-Systems (MEMS) technologies, that have multiple fluidic access ports (e.g. 100 micron diameter) within a small footprint, (e.g. 3 mm.times.6 mm). Fanout of the small ports of a microfluidic device to a larger diameter (e.g. 500 microns) facilitates packaging and interconnection of the microfluidic device to printed wiring boards, electronics packages, fluidic manifolds etc.

Accessing microfluidics through feature-based design software for 3D printing.

PubMed

Shankles, Peter G; Millet, Larry J; Aufrecht, Jayde A; Retterer, Scott T

2018-01-01

Additive manufacturing has been a cornerstone of the product development pipeline for decades, playing an essential role in the creation of both functional and cosmetic prototypes. In recent years, the prospects for distributed and open source manufacturing have grown tremendously. This growth has been enabled by an expanding library of printable materials, low-cost printers, and communities dedicated to platform development. The microfluidics community has embraced this opportunity to integrate 3D printing into the suite of manufacturing strategies used to create novel fluidic architectures. The rapid turnaround time and low cost to implement these strategies in the lab makes 3D printing an attractive alternative to conventional micro- and nanofabrication techniques. In this work, the production of multiple microfluidic architectures using a hybrid 3D printing-soft lithography approach is demonstrated and shown to enable rapid device fabrication with channel dimensions that take advantage of laminar flow characteristics. The fabrication process outlined here is underpinned by the implementation of custom design software with an integrated slicer program that replaces less intuitive computer aided design and slicer software tools. Devices are designed in the program by assembling parameterized microfluidic building blocks. The fabrication process and flow control within 3D printed devices were demonstrated with a gradient generator and two droplet generator designs. Precise control over the printing process allowed 3D microfluidics to be printed in a single step by extruding bridge structures to 'jump-over' channels in the same plane. This strategy was shown to integrate with conventional nanofabrication strategies to simplify the operation of a platform that incorporates both nanoscale features and 3D printed microfluidics.

Accessing microfluidics through feature-based design software for 3D printing

PubMed Central

Shankles, Peter G.; Millet, Larry J.; Aufrecht, Jayde A.

2018-01-01

Additive manufacturing has been a cornerstone of the product development pipeline for decades, playing an essential role in the creation of both functional and cosmetic prototypes. In recent years, the prospects for distributed and open source manufacturing have grown tremendously. This growth has been enabled by an expanding library of printable materials, low-cost printers, and communities dedicated to platform development. The microfluidics community has embraced this opportunity to integrate 3D printing into the suite of manufacturing strategies used to create novel fluidic architectures. The rapid turnaround time and low cost to implement these strategies in the lab makes 3D printing an attractive alternative to conventional micro- and nanofabrication techniques. In this work, the production of multiple microfluidic architectures using a hybrid 3D printing-soft lithography approach is demonstrated and shown to enable rapid device fabrication with channel dimensions that take advantage of laminar flow characteristics. The fabrication process outlined here is underpinned by the implementation of custom design software with an integrated slicer program that replaces less intuitive computer aided design and slicer software tools. Devices are designed in the program by assembling parameterized microfluidic building blocks. The fabrication process and flow control within 3D printed devices were demonstrated with a gradient generator and two droplet generator designs. Precise control over the printing process allowed 3D microfluidics to be printed in a single step by extruding bridge structures to ‘jump-over’ channels in the same plane. This strategy was shown to integrate with conventional nanofabrication strategies to simplify the operation of a platform that incorporates both nanoscale features and 3D printed microfluidics. PMID:29596418

Direct integration of MEMS, dielectric pumping and cell manipulation with reversibly bonded gecko adhesive microfluidics

NASA Astrophysics Data System (ADS)

Warnat, S.; King, H.; Wasay, A.; Sameoto, D.; Hubbard, T.

2016-09-01

We present an approach to form a microfluidic environment on top of MEMS dies using reversibly bonded microfluidics. The reversible polymeric microfluidics moulds bond to the MEMS die using a gecko-inspired gasket architecture. In this study the formed microchannels are demonstrated in conjunction with a MEMS mechanical single cell testing environment for BioMEMS applications. A reversible microfluidics placement technique with an x-y and rotational accuracy of  ±2 µm and 1° respectively on a MEMS die was developed. No leaks were observed during pneumatic pumping of common cell media (PBS, sorbitol, water, seawater) through the fluidic channels. Thermal chevron actuators were successful operated inside this fluidic environment and a performance deviation of ~15% was measured compared to an open MEMS configuration. Latex micro-spheres were pumped using traveling wave di-electrophoresis and compared to an open (no-microfluidics) configuration with velocities of 24 µm s-1 and 20 µm s-1.

Fluorescence Time-lapse Imaging of the Complete S. venezuelae Life Cycle Using a Microfluidic Device.

PubMed

Schlimpert, Susan; Flärdh, Klas; Buttner, Mark

2016-02-28

Live-cell imaging of biological processes at the single cell level has been instrumental to our current understanding of the subcellular organization of bacterial cells. However, the application of time-lapse microscopy to study the cell biological processes underpinning development in the sporulating filamentous bacteria Streptomyces has been hampered by technical difficulties. Here we present a protocol to overcome these limitations by growing the new model species, Streptomyces venezuelae, in a commercially available microfluidic device which is connected to an inverted fluorescence widefield microscope. Unlike the classical model species, Streptomyces coelicolor, S. venezuelae sporulates in liquid, allowing the application of microfluidic growth chambers to cultivate and microscopically monitor the cellular development and differentiation of S. venezuelae over long time periods. In addition to monitoring morphological changes, the spatio-temporal distribution of fluorescently labeled target proteins can also be visualized by time-lapse microscopy. Moreover, the microfluidic platform offers the experimental flexibility to exchange the culture medium, which is used in the detailed protocol to stimulate sporulation of S. venezuelae in the microfluidic chamber. Images of the entire S. venezuelae life cycle are acquired at specific intervals and processed in the open-source software Fiji to produce movies of the recorded time-series.

Fluorescence Time-lapse Imaging of the Complete S. venezuelae Life Cycle Using a Microfluidic Device

PubMed Central

Schlimpert, Susan; Flärdh, Klas; Buttner, Mark

2016-01-01

Live-cell imaging of biological processes at the single cell level has been instrumental to our current understanding of the subcellular organization of bacterial cells. However, the application of time-lapse microscopy to study the cell biological processes underpinning development in the sporulating filamentous bacteria Streptomyces has been hampered by technical difficulties. Here we present a protocol to overcome these limitations by growing the new model species, Streptomyces venezuelae, in a commercially available microfluidic device which is connected to an inverted fluorescence widefield microscope. Unlike the classical model species, Streptomyces coelicolor, S. venezuelae sporulates in liquid, allowing the application of microfluidic growth chambers to cultivate and microscopically monitor the cellular development and differentiation of S. venezuelae over long time periods. In addition to monitoring morphological changes, the spatio-temporal distribution of fluorescently labeled target proteins can also be visualized by time-lapse microscopy. Moreover, the microfluidic platform offers the experimental flexibility to exchange the culture medium, which is used in the detailed protocol to stimulate sporulation of S. venezuelae in the microfluidic chamber. Images of the entire S. venezuelae life cycle are acquired at specific intervals and processed in the open-source software Fiji to produce movies of the recorded time-series. PMID:26967231

Microfluidics and Raman microscopy: current applications and future challenges.

PubMed

Chrimes, Adam F; Khoshmanesh, Khashayar; Stoddart, Paul R; Mitchell, Arnan; Kalantar-Zadeh, Kourosh

2013-07-07

Raman microscopy systems are becoming increasingly widespread and accessible for characterising chemical species. Microfluidic systems are also progressively finding their way into real world applications. Therefore, it is anticipated that the integration of Raman systems with microfluidics will become increasingly attractive and practical. This review aims to provide an overview of Raman microscopy-microfluidics integrated systems for researchers who are actively interested in utilising these tools. The fundamental principles and application strengths of Raman microscopy are discussed in the context of microfluidics. Various configurations of microfluidics that incorporate Raman microscopy methods are presented, with applications highlighted. Data analysis methods are discussed, with a focus on assisting the interpretation of Raman-microfluidics data from complex samples. Finally, possible future directions of Raman-microfluidic systems are presented.

Upgrading well plates using open microfluidic patterning.

PubMed

Berry, Samuel B; Zhang, Tianzi; Day, John H; Su, Xiaojing; Wilson, Ilham Z; Berthier, Erwin; Theberge, Ashleigh B

2017-12-05

Cellular communication between multiple cell types is a ubiquitous process that is responsible for vital physiological responses observed in vivo (e.g., immune response, organ function). Many in vitro coculture strategies have been developed, both in traditional culture and microscale systems, and have shown the potential to recreate some of the physiological behaviors of organs or groups of cells. A fundamental limitation of current systems is the difficulty of reconciling the additional engineering requirements for creating soluble factor signaling systems (e.g., segregated cell culture) with the use of well-characterized materials and platforms that have demonstrated successful results and biocompatibility in assays. We present a new open-microfluidic platform, the Monorail Device, that is placed in any existing well plate or Petri dish and enables patterning of segregated coculture regions, thereby allowing the direct upgrade of monoculture experiments into multiculture assays. Our platform patterns biocompatible hydrogel walls via microfluidic spontaneous capillary flow (SCF) along a rail insert set inside commercially available cultureware, creating customized pipette-accessible cell culture chambers that require fewer cells than standard macroscale culture. Importantly, the device allows the use of native surfaces without additional modification or treatments, while creating permeable dividers for the diffusion of soluble factors. Additionally, the ease of patterning afforded by our platform makes reconfiguration of the culture region as simple as changing the rail insert. We demonstrate the ability of the device to pattern flows on a variety of cell culture surfaces and create hydrogel walls in complex and precise shapes. We characterize the physical parameters that enable a reproducible SCF-driven flow and highlight specialized design features that increase the ease of use of the device and control of the open microfluidic flow. Further, we present the performance of our platform according to useful coculture criteria, including permeability and integrity of our hydrogel walls and surface-sensitive cell culture. Lastly, we show the potential of this type of platform to create modular multikingdom culture systems that can be used to study soluble factor signaling between mammalian cells, bacteria, and fungi, as well as the potential for adaptation of this technology by researchers across multiple fields.

Closed-loop feedback control for microfluidic systems through automated capacitive fluid height sensing.

PubMed

Soenksen, L R; Kassis, T; Noh, M; Griffith, L G; Trumper, D L

2018-03-13

Precise fluid height sensing in open-channel microfluidics has long been a desirable feature for a wide range of applications. However, performing accurate measurements of the fluid level in small-scale reservoirs (<1 mL) has proven to be an elusive goal, especially if direct fluid-sensor contact needs to be avoided. In particular, gravity-driven systems used in several microfluidic applications to establish pressure gradients and impose flow remain open-loop and largely unmonitored due to these sensing limitations. Here we present an optimized self-shielded coplanar capacitive sensor design and automated control system to provide submillimeter fluid-height resolution (∼250 μm) and control of small-scale open reservoirs without the need for direct fluid contact. Results from testing and validation of our optimized sensor and system also suggest that accurate fluid height information can be used to robustly characterize, calibrate and dynamically control a range of microfluidic systems with complex pumping mechanisms, even in cell culture conditions. Capacitive sensing technology provides a scalable and cost-effective way to enable continuous monitoring and closed-loop feedback control of fluid volumes in small-scale gravity-dominated wells in a variety of microfluidic applications.

Ice matrix in reconfigurable microfluidic systems

NASA Astrophysics Data System (ADS)

Bossi, A. M.; Vareijka, M.; Piletska, E. V.; Turner, A. P. F.; Meglinski, I.; Piletsky, S. A.

2013-07-01

Microfluidic devices find many applications in biotechnologies. Here, we introduce a flexible and biocompatible microfluidic ice-based platform with tunable parameters and configuration of microfluidic patterns that can be changed multiple times during experiments. Freezing and melting of cavities, channels and complex relief structures created and maintained in the bulk of ice by continuous scanning of an infrared laser beam are used as a valve action in microfluidic systems. We demonstrate that pre-concentration of samples and transport of ions and dyes through the open channels created can be achieved in ice microfluidic patterns by IR laser-assisted zone melting. The proposed approach can be useful for performing separation and sensing processes in flexible reconfigurable microfluidic devices.

Multiwell capillarity-based microfluidic device for the study of 3D tumour tissue-2D endothelium interactions and drug screening in co-culture models.

PubMed

Virumbrales-Muñoz, María; Ayuso, José María; Olave, Marta; Monge, Rosa; de Miguel, Diego; Martínez-Lostao, Luis; Le Gac, Séverine; Doblare, Manuel; Ochoa, Ignacio; Fernandez, Luis J

2017-09-20

The tumour microenvironment is very complex, and essential in tumour development and drug resistance. The endothelium is critical in the tumour microenvironment: it provides nutrients and oxygen to the tumour and is essential for systemic drug delivery. Therefore, we report a simple, user-friendly microfluidic device for co-culture of a 3D breast tumour model and a 2D endothelium model for cross-talk and drug delivery studies. First, we demonstrated the endothelium was functional, whereas the tumour model exhibited in vivo features, e.g., oxygen gradients and preferential proliferation of cells with better access to nutrients and oxygen. Next, we observed the endothelium structure lost its integrity in the co-culture. Following this, we evaluated two drug formulations of TRAIL (TNF-related apoptosis inducing ligand): soluble and anchored to a LUV (large unilamellar vesicle). Both diffused through the endothelium, LUV-TRAIL being more efficient in killing tumour cells, showing no effect on the integrity of endothelium. Overall, we have developed a simple capillary force-based microfluidic device for 2D and 3D cell co-cultures. Our device allows high-throughput approaches, patterning different cell types and generating gradients without specialised equipment. We anticipate this microfluidic device will facilitate drug screening in a relevant microenvironment thanks to its simple, effective and user-friendly operation.

Twisting microfluidics in a planetary centrifuge.

PubMed

Yasuda, Shoya; Hayakawa, Masayuki; Onoe, Hiroaki; Takinoue, Masahiro

2017-03-15

This paper reports a twisting microfluidic method utilising a centrifuge-based fluid extruding system in a planetary centrifuge which simultaneously generates an orbital rotation and an axial spin. In this method, fluid extrusion from a micro-scale capillary to an 'open-space' solution or air enables release of the fluid from the capillary-based microchannel, which physically means that there is a release of fluids from a confined low-Reynolds-number environment to an open non-low-Reynolds-number environment. As a result, the extruded fluids are separated from the axial spin of the capillary, and the difference in the angular rates of the axial spin between the capillary and the extruded fluids produces the 'twisting' of the fluid. In this study, we achieve control of the twist of highly viscous fluids, and we construct a simple physical model for the fluid twist. In addition, we demonstrate the formation of twisted hydrogel microstructures (stripe-patterned microbeads and multi-helical microfibres) with control over the stripe pattern and the helical pitch length. We believe that this method will enable the generation of more sophisticated microstructures which cannot easily be formed by usual channel-based microfluidic devices. This method can also provide advanced control of microfluids, as in the case of rapid mixing of highly viscous fluids. This method can contribute to a wide range of applications in materials science, biophysics, biomedical science, and microengineering in the future.

Fabrication and Operation of Microfluidic Hanging-Drop Networks.

PubMed

Misun, Patrick M; Birchler, Axel K; Lang, Moritz; Hierlemann, Andreas; Frey, Olivier

2018-01-01

The hanging-drop network (HDN) is a technology platform based on a completely open microfluidic network at the bottom of an inverted, surface-patterned substrate. The platform is predominantly used for the formation, culturing, and interaction of self-assembled spherical microtissues (spheroids) under precisely controlled flow conditions. Here, we describe design, fabrication, and operation of microfluidic hanging-drop networks.

Integrated microfluidic platforms for investigating neuronal networks

NASA Astrophysics Data System (ADS)

Kim, Hyung Joon

This dissertation describes the development and application of integrated microfluidics-based assay platforms to study neuronal activities in the nervous system in-vitro. The assay platforms were fabricated using soft lithography and micro/nano fabrication including microfluidics, surface patterning, and nanomaterial synthesis. The use of integrated microfluidics-based assay platform allows culturing and manipulating many types of neuronal tissues in precisely controlled microenvironment. Furthermore, they provide organized multi-cellular in-vitro model, long-term monitoring with live cell imaging, and compatibility with molecular biology techniques and electrophysiology experiment. In this dissertation, the integrated microfluidics-based assay platforms are developed for investigation of neuronal activities such as local protein synthesis, impairment of axonal transport by chemical/physical variants, growth cone path finding under chemical/physical cues, and synaptic transmission in neuronal circuit. Chapter 1 describes the motivation, objectives, and scope for developing in-vitro platform to study various neuronal activities. Chapter 2 introduces microfluidic culture platform for biochemical assay with large-scale neuronal tissues that are utilized as model system in neuroscience research. Chapter 3 focuses on the investigation of impaired axonal transport by beta-Amyloid and oxidative stress. The platform allows to control neuronal processes and to quantify mitochondrial movement in various regions of axons away from applied drugs. Chapter 4 demonstrates the development of microfluidics-based growth cone turning assay to elucidate the mechanism underlying axon guidance under soluble factors and shear flow. Using this platform, the behaviors of growth cone of mammalian neurons are verified under the gradient of inhibitory molecules and also shear flow in well-controlled manner. In Chapter 5, I combine in-vitro multicellular model with microfabricated MEA (multielectrode array) or nanowire electrode array to study electrophysiology in neuronal network. Also, "diode-like" microgrooves to control the number of neuronal processes is embedded in this platform. Chapter 6 concludes with a possible future direction of this work. Interfacing micro/nanotechnology with primary neuron culture would open many doors in fundamental neuroscience research and also biomedical innovation.

Questioning the efficacy of 'gold' open access to published articles.

PubMed

Fredericks, Suzanne

2015-07-01

To question the efficacy of 'gold' open access to published articles. Open access is unrestricted access to academic, theoretical and research literature that is scholarly and peer-reviewed. Two models of open access exist: 'gold' and 'green'. Gold open access provides everyone with access to articles during all stages of publication, with processing charges paid by the author(s). Green open access involves placing an already published article into a repository to provide unrestricted access, with processing charges incurred by the publisher. This is a discussion paper. An exploration of the relative benefits and drawbacks of the 'gold' and 'green' open access systems. Green open access is a more economic and efficient means of granting open access to scholarly literature but a large number of researchers select gold open access journals as their first choices for manuscript submissions. This paper questions the efficacy of gold open access models and presents an examination of green open access models to encourage nurse researchers to consider this approach. In the current academic environment, with increased pressures to publish and low funding success rates, it is difficult to understand why gold open access still exists. Green open access enhances the visibility of an academic's work, as increased downloads of articles tend to lead to increased citations. Green open access is the cheaper option, as well as the most beneficial choice, for universities that want to provide unrestricted access to all literature at minimal risk.

Low-cost feedback-controlled syringe pressure pumps for microfluidics applications.

PubMed

Lake, John R; Heyde, Keith C; Ruder, Warren C

2017-01-01

Microfluidics are widely used in research ranging from bioengineering and biomedical disciplines to chemistry and nanotechnology. As such, there are a large number of options for the devices used to drive and control flow through microfluidic channels. Commercially available syringe pumps are probably the most commonly used instruments for this purpose, but are relatively high-cost and have inherent limitations due to their flow profiles when they are run open-loop. Here, we present a low-cost ($110) syringe pressure pump that uses feedback control to regulate the pressure into microfluidic chips. Using an open-source microcontroller board (Arduino), we demonstrate an easily operated and programmable syringe pump that can be run using either a PID or bang-bang control method. Through feedback control of the pressure at the inlets of two microfluidic geometries, we have shown stability of our device to within ±1% of the set point using a PID control method and within ±5% of the set point using a bang-bang control method with response times of less than 1 second. This device offers a low-cost option to drive and control well-regulated pressure-driven flow through microfluidic chips.

Low-cost feedback-controlled syringe pressure pumps for microfluidics applications

PubMed Central

Lake, John R.; Heyde, Keith C.

2017-01-01

Microfluidics are widely used in research ranging from bioengineering and biomedical disciplines to chemistry and nanotechnology. As such, there are a large number of options for the devices used to drive and control flow through microfluidic channels. Commercially available syringe pumps are probably the most commonly used instruments for this purpose, but are relatively high-cost and have inherent limitations due to their flow profiles when they are run open-loop. Here, we present a low-cost ($110) syringe pressure pump that uses feedback control to regulate the pressure into microfluidic chips. Using an open-source microcontroller board (Arduino), we demonstrate an easily operated and programmable syringe pump that can be run using either a PID or bang-bang control method. Through feedback control of the pressure at the inlets of two microfluidic geometries, we have shown stability of our device to within ±1% of the set point using a PID control method and within ±5% of the set point using a bang-bang control method with response times of less than 1 second. This device offers a low-cost option to drive and control well-regulated pressure-driven flow through microfluidic chips. PMID:28369134

Anodically bonded submicron microfluidic chambers.

PubMed

Dimov, S; Bennett, R G; Córcoles, A; Levitin, L V; Ilic, B; Verbridge, S S; Saunders, J; Casey, A; Parpia, J M

2010-01-01

We demonstrate the use of anodic bonding to fabricate cells with characteristic size as large as 7 x 10 mm(2), with height of approximately 640 nm, and without any internal support structure. The cells were fabricated from Hoya SD-2 glass and silicon wafers, each with 3 mm thickness to maintain dimensional stability under internal pressure. Bonding was carried out at 350 degrees C and 450 V with an electrode structure that excluded the electric field from the open region. We detail fabrication and characterization steps and also discuss the design of the fill line for access to the cavity.

A microfluidic device to study neuronal and motor responses to acute chemical stimuli in zebrafish.

PubMed

Candelier, Raphaël; Murmu, Meena Sriti; Romano, Sebastián Alejo; Jouary, Adrien; Debrégeas, Georges; Sumbre, Germán

2015-07-21

Zebrafish larva is a unique model for whole-brain functional imaging and to study sensory-motor integration in the vertebrate brain. To take full advantage of this system, one needs to design sensory environments that can mimic the complex spatiotemporal stimulus patterns experienced by the animal in natural conditions. We report on a novel open-ended microfluidic device that delivers pulses of chemical stimuli to agarose-restrained larvae with near-millisecond switching rate and unprecedented spatial and concentration accuracy and reproducibility. In combination with two-photon calcium imaging and recordings of tail movements, we found that stimuli of opposite hedonic values induced different circuit activity patterns. Moreover, by precisely controlling the duration of the stimulus (50-500 ms), we found that the probability of generating a gustatory-induced behavior is encoded by the number of neurons activated. This device may open new ways to dissect the neural-circuit principles underlying chemosensory perception.

Cost-effective rapid prototyping and assembly of poly(methyl methacrylate) microfluidic devices.

PubMed

Matellan, Carlos; Del Río Hernández, Armando E

2018-05-03

The difficulty in translating conventional microfluidics from laboratory prototypes to commercial products has shifted research efforts towards thermoplastic materials for their higher translational potential and amenability to industrial manufacturing. Here, we present an accessible method to fabricate and assemble polymethyl methacrylate (PMMA) microfluidic devices in a "mask-less" and cost-effective manner that can be applied to manufacture a wide range of designs due to its versatility. Laser micromachining offers high flexibility in channel dimensions and morphology by controlling the laser properties, while our two-step surface treatment based on exposure to acetone vapour and low-temperature annealing enables improvement of the surface quality without deformation of the device. Finally, we demonstrate a capillarity-driven adhesive delivery bonding method that can produce an effective seal between PMMA devices and a variety of substrates, including glass, silicon and LiNbO 3 . We illustrate the potential of this technique with two microfluidic devices, an H-filter and a droplet generator. The technique proposed here offers a low entry barrier for the rapid prototyping of thermoplastic microfluidics, enabling iterative design for laboratories without access to conventional microfabrication equipment.

Analyzing threshold pressure limitations in microfluidic transistors for self-regulated microfluidic circuits.

PubMed

Kim, Sung-Jin; Yokokawa, Ryuji; Takayama, Shuichi

2012-12-03

This paper reveals a critical limitation in the electro-hydraulic analogy between a microfluidic membrane-valve (μMV) and an electronic transistor. Unlike typical transistors that have similar on and off threshold voltages, in hydraulic μMVs, the threshold pressures for opening and closing are significantly different and can change, even for the same μMVs depending on overall circuit design and operation conditions. We explain, in particular, how the negative values of the closing threshold pressures significantly constrain operation of even simple hydraulic μMV circuits such as autonomously switching two-valve microfluidic oscillators. These understandings have significant implications in designing self-regulated microfluidic devices.

Methods and Devices for Micro-Isolation, Extraction, and/or Analysis of Microscale Components

NASA Technical Reports Server (NTRS)

Wade, Lawrence A. (Inventor); Kartalov, Emil P. (Inventor); Taylor, Clive (Inventor); Shibata, Darryl (Inventor)

2014-01-01

Provided herein are devices and methods for the micro-isolation of biological cellular material. A micro-isolation apparatus described can comprise a photomask that protects regions of interest against DNA-destroying illumination. The micro-isolation apparatus can further comprise photosensitive material defining access wells following illumination and subsequent developing of the photosensitive material. The micro-isolation apparatus can further comprise a chambered microfluidic device comprising channels providing access to wells defined in photosensitive material. The micro-isolation apparatus can comprise a chambered microfluidic device without access wells defined in photosensitive material where valves control the flow of gases or liquids through the channels of the microfluidic device. Also included are methods for selectively isolating cellular material using the apparatuses described herein, as are methods for biochemical analysis of individual regions of interest of cellular material using the devices described herein. Further included are methods of making masking arrays useful for the methods described herein.

In-plane cost-effective magnetically actuated valve for microfluidic applications

NASA Astrophysics Data System (ADS)

Pugliese, Marco; Ferrara, Francesco; Bramanti, Alessandro Paolo; Gigli, Giuseppe; Maiorano, Vincenzo

2017-04-01

We present a new in-plane magnetically actuated microfluidic valve. Its simple design includes a circular area joining two channels lying on the same plane. The area is parted by a septum lying on and adhering to a magneto-active polymeric ‘floor’ membrane, keeping the channels normally separated (valve closed). Under the action of a magnetic field, the membrane collapses, letting the liquid flow below the septum (valve open). The valve was extensively characterized experimentally, and modeled and optimized theoretically. The growing interest in lab on chips, especially for diagnostics and precision medicine, is driving researchers towards smart, efficient and low cost solutions to the management of biological samples. In this context, the valve developed in this work represents a useful building-block for microfluidic applications requiring precise flow control, its main features being easy and rapid manufacturing, biocompatibility and low cost.

The continued movement for open access to peer-reviewed literature.

PubMed

Liesegang, Thomas J

2013-09-01

To provide a current overview of the movement for open access to the peer review literature. Perspective. Literature review of recent advances in the open access movement with a personal viewpoint of the nuances of the movement. The open access movement is complex, with many different constituents. The idealists for the open access movement are seeking open access to the literature but also to the data that constitute the research within the manuscript. The business model of the traditional subscription journal is being scrutinized in relation to the surge in the number of open access journals. Within this environment authors should beware predatory practices. More government and funding agencies are mandating open access to their funded research. This open access movement will continue to be disruptive until a business model ensures continuity of the scientific record. A flood of open access articles that might enrich, but also might pollute or confuse, the medical literature has altered the filtering mechanism provided by the traditional peer review system. At some point there may be a shake-out, with some literature being lost in cyberspace. The open access movement is maturing and must be embraced in some format. The challenge is to establish a sustainable financial business model that will permit the use of digital technology but yet not endanger the decades-old traditional publication model and peer review system. Authors seem to be slower in adopting open access than the idealists in the movement. Copyright © 2013 Elsevier Inc. All rights reserved.

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.

A reversibly sealed, easy access, modular (SEAM) microfluidic architecture to establish in vitro tissue interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abhyankar, Vinay V.; Wu, Meiye; Koh, Chung -Yan

Microfluidic barrier tissue models have emerged as advanced in vitro tools to explore interactions with external stimuli such as drug candidates, pathogens, or toxins. However, the procedures required to establish and maintain these systems can be challenging to implement for end users, particularly those without significant in-house engineering expertise. Here we present a module-based approach that provides an easy-to-use workflow to establish, maintain, and analyze microscale tissue constructs. Our approach begins with a removable culture insert that is magnetically coupled, decoupled, and transferred between standalone, prefabricated microfluidic modules for simplified cell seeding, culture, and downstream analysis. The modular approach allowsmore » several options for perfusion including standard syringe pumps or integration with a self-contained gravity-fed module for simple cell maintenance. As proof of concept, we establish a culture of primary human microvascular endothelial cells (HMVEC) and report combined surface protein imaging and gene expression after controlled apical stimulation with the bacterial endotoxin lipopolysaccharide (LPS). We also demonstrate the feasibility of incorporating hydrated biomaterial interfaces into the microfluidic architecture by integrating an ultra-thin (< 1 μm), self-assembled hyaluronic acid/peptide amphiphile culture membrane with brain-specific Young’s modulus (~ 1kPa). To highlight the importance of including biomimetic interfaces into microscale models we report multi-tiered readouts from primary rat cortical cells cultured on the self-assembled membrane and compare a panel of mRNA targets with primary brain tissue signatures. As a result, we anticipate that the modular approach and simplified operational workflows presented here will enable a wide range of research groups to incorporate microfluidic barrier tissue models into their work.« less

A reversibly sealed, easy access, modular (SEAM) microfluidic architecture to establish in vitro tissue interfaces

DOE PAGES

Abhyankar, Vinay V.; Wu, Meiye; Koh, Chung -Yan; ...

2016-05-26

Microfluidic barrier tissue models have emerged as advanced in vitro tools to explore interactions with external stimuli such as drug candidates, pathogens, or toxins. However, the procedures required to establish and maintain these systems can be challenging to implement for end users, particularly those without significant in-house engineering expertise. Here we present a module-based approach that provides an easy-to-use workflow to establish, maintain, and analyze microscale tissue constructs. Our approach begins with a removable culture insert that is magnetically coupled, decoupled, and transferred between standalone, prefabricated microfluidic modules for simplified cell seeding, culture, and downstream analysis. The modular approach allowsmore » several options for perfusion including standard syringe pumps or integration with a self-contained gravity-fed module for simple cell maintenance. As proof of concept, we establish a culture of primary human microvascular endothelial cells (HMVEC) and report combined surface protein imaging and gene expression after controlled apical stimulation with the bacterial endotoxin lipopolysaccharide (LPS). We also demonstrate the feasibility of incorporating hydrated biomaterial interfaces into the microfluidic architecture by integrating an ultra-thin (< 1 μm), self-assembled hyaluronic acid/peptide amphiphile culture membrane with brain-specific Young’s modulus (~ 1kPa). To highlight the importance of including biomimetic interfaces into microscale models we report multi-tiered readouts from primary rat cortical cells cultured on the self-assembled membrane and compare a panel of mRNA targets with primary brain tissue signatures. As a result, we anticipate that the modular approach and simplified operational workflows presented here will enable a wide range of research groups to incorporate microfluidic barrier tissue models into their work.« less

Analyzing threshold pressure limitations in microfluidic transistors for self-regulated microfluidic circuits

PubMed Central

Kim, Sung-Jin; Yokokawa, Ryuji; Takayama, Shuichi

2012-01-01

This paper reveals a critical limitation in the electro-hydraulic analogy between a microfluidic membrane-valve (μMV) and an electronic transistor. Unlike typical transistors that have similar on and off threshold voltages, in hydraulic μMVs, the threshold pressures for opening and closing are significantly different and can change, even for the same μMVs depending on overall circuit design and operation conditions. We explain, in particular, how the negative values of the closing threshold pressures significantly constrain operation of even simple hydraulic μMV circuits such as autonomously switching two-valve microfluidic oscillators. These understandings have significant implications in designing self-regulated microfluidic devices. PMID:23284181

Microfluidic resonant waveguide grating biosensor system for whole cell sensing

NASA Astrophysics Data System (ADS)

Zaytseva, Natalya; Miller, William; Goral, Vasily; Hepburn, Jerry; Fang, Ye

2011-04-01

We report on a fluidic resonant waveguide grating (RWG) biosensor system that enables medium throughput measurements of cellular responses under microfluidics in a 32-well format. Dynamic mass redistribution assays under microfluidics differentiate the cross-desensitization process between the β2-adrenoceptor agonist epinephrine and the adenylate cyclase activator forskolin mediated signaling. This system opens new possibility to study cellular processes that are otherwise difficult to achieve using conventional RWG configurations.

Open Access Publishing - Strengths and Strategies

NASA Astrophysics Data System (ADS)

Rasmussen, Martin

2010-05-01

The journal crisis and the demand for free accessibility to the results of publicly funded research were the main drivers of the Open Access movement since the late 1990's. Besides many academic institutions that support the different ways of Open Access publishing, there is a growing number of publishing houses that are specialized on this new access and business model of scholarly literature. The lecture provides an overview of the different kinds of Open Access publishing, discusses the variety of underlying business models, names the advantages and potentials for researches and the public, and overcomes some objections against Open Access. Besides the increased visibility and information supply, the topic of copyrights and exploitation rights will be discussed. Furthermore, it is a central aim of the presentation to show that Open Access does not only support full peer-review, but also provides the potential for even enhanced quality assurance. The financing of business models based on open accessible literature is another important part to be outlined in the lecture.

Reasons to temper enthusiasm about open access nursing journals.

PubMed

de Jong, Gideon

2017-04-01

Open access is a relatively new phenomenon within nursing science. Several papers from various nursing journals have been published recently on the disadvantages of the traditional model of purchasing proprietary fee-based databases to access scholarly information. Just few nursing scholars are less optimistic about the possible benefits of open access nursing journals. A critical reflection on the merits and pitfalls of open access journals along insights from the literature and personal opinion. Two arguments are discussed, providing justification for tempering enthusiasm about open access journals. First, only research groups with sufficient financial resources can publish in open access journals. Second, open access has conflicting incentives, where the aim is to expand production at the expense of publishing quality articles; a business model that fits well into a neoliberal discourse. There are valid reasons to criticise the traditional publishers for the excessive costs of a single article, therefore preventing the dissemination of scholarly nursing information. On the contrary, the business model of open access publishers is no less imbued with the neoliberal tendency of lining the pockets.

Surface acoustic wave microfluidics

PubMed Central

Ding, Xiaoyun; Li, Peng; Lin, Sz-Chin Steven; Stratton, Zackary S.; Nama, Nitesh; Guo, Feng; Slotcavage, Daniel; Mao, Xiaole; Shi, Jinjie; Costanzo, Francesco; Huang, Tony Jun

2014-01-01

The recent introduction of surface acoustic wave (SAW) technology onto lab-on-a-chip platforms has opened a new frontier in microfluidics. The advantages provided by such SAW microfluidics are numerous: simple fabrication, high biocompatibility, fast fluid actuation, versatility, compact and inexpensive devices and accessories, contact-free particle manipulation, and compatibility with other microfluidic components. We believe that these advantages enable SAW microfluidics to play a significant role in a variety of applications in biology, chemistry, engineering, and medicine. In this review article, we discuss the theory underpinning SAWs and their interactions with particles and the contacting fluids in which they are suspended. We then review the SAW-enabled microfluidic devices demonstrated to date, starting with devices that accomplish fluid mixing and transport through the use of travelling SAW; we follow that by reviewing the more recent innovations achieved with standing SAW that enable such actions as particle/cell focusing, sorting, and patterning. Finally, we look forward and appraise where the discipline of SAW microfluidics could go next. PMID:23900527

Microfluidic CODES: a scalable multiplexed electronic sensor for orthogonal detection of particles in microfluidic channels.

PubMed

Liu, Ruxiu; Wang, Ningquan; Kamili, Farhan; Sarioglu, A Fatih

2016-04-21

Numerous biophysical and biochemical assays rely on spatial manipulation of particles/cells as they are processed on lab-on-a-chip devices. Analysis of spatially distributed particles on these devices typically requires microscopy negating the cost and size advantages of microfluidic assays. In this paper, we introduce a scalable electronic sensor technology, called microfluidic CODES, that utilizes resistive pulse sensing to orthogonally detect particles in multiple microfluidic channels from a single electrical output. Combining the techniques from telecommunications and microfluidics, we route three coplanar electrodes on a glass substrate to create multiple Coulter counters producing distinct orthogonal digital codes when they detect particles. We specifically design a digital code set using the mathematical principles of Code Division Multiple Access (CDMA) telecommunication networks and can decode signals from different microfluidic channels with >90% accuracy through computation even if these signals overlap. As a proof of principle, we use this technology to detect human ovarian cancer cells in four different microfluidic channels fabricated using soft lithography. Microfluidic CODES offers a simple, all-electronic interface that is well suited to create integrated, low-cost lab-on-a-chip devices for cell- or particle-based assays in resource-limited settings.

Advances in microfluidic devices made from thermoplastics used in cell biology and analyses.

PubMed

Gencturk, Elif; Mutlu, Senol; Ulgen, Kutlu O

2017-09-01

Silicon and glass were the main fabrication materials of microfluidic devices, however, plastics are on the rise in the past few years. Thermoplastic materials have recently been used to fabricate microfluidic platforms to perform experiments on cellular studies or environmental monitoring, with low cost disposable devices. This review describes the present state of the development and applications of microfluidic systems used in cell biology and analyses since the year 2000. Cultivation, separation/isolation, detection and analysis, and reaction studies are extensively discussed, considering only microorganisms (bacteria, yeast, fungi, zebra fish, etc.) and mammalian cell related studies in the microfluidic platforms. The advantages/disadvantages, fabrication methods, dimensions, and the purpose of creating the desired system are explained in detail. An important conclusion of this review is that these microfluidic platforms are still open for research and development, and solutions need to be found for each case separately.

The microfluidics of the eccrine sweat gland, including biomarker partitioning, transport, and biosensing implications

PubMed Central

Sonner, Z.; Wilder, E.; Heikenfeld, J.; Kasting, G.; Beyette, F.; Swaile, D.; Sherman, F.; Joyce, J.; Hagen, J.; Kelley-Loughnane, N.; Naik, R.

2015-01-01

Non-invasive and accurate access of biomarkers remains a holy grail of the biomedical community. Human eccrine sweat is a surprisingly biomarker-rich fluid which is gaining increasing attention. This is especially true in applications of continuous bio-monitoring where other biofluids prove more challenging, if not impossible. However, much confusion on the topic exists as the microfluidics of the eccrine sweat gland has never been comprehensively presented and models of biomarker partitioning into sweat are either underdeveloped and/or highly scattered across literature. Reported here are microfluidic models for eccrine sweat generation and flow which are coupled with review of blood-to-sweat biomarker partition pathways, therefore providing insights such as how biomarker concentration changes with sweat flow rate. Additionally, it is shown that both flow rate and biomarker diffusion determine the effective sampling rate of biomarkers at the skin surface (chronological resolution). The discussion covers a broad class of biomarkers including ions (Na+, Cl−, K+, NH4+), small molecules (ethanol, cortisol, urea, and lactate), and even peptides or small proteins (neuropeptides and cytokines). The models are not meant to be exhaustive for all biomarkers, yet collectively serve as a foundational guide for further development of sweat-based diagnostics and for those beginning exploration of new biomarker opportunities in sweat. PMID:26045728

A novel microfluidic model can mimic organ-specific metastasis of circulating tumor cells.

PubMed

Kong, Jing; Luo, Yong; Jin, Dong; An, Fan; Zhang, Wenyuan; Liu, Lilu; Li, Jiao; Fang, Shimeng; Li, Xiaojie; Yang, Xuesong; Lin, Bingcheng; Liu, Tingjiao

2016-11-29

A biomimetic microsystem might compensate costly and time-consuming animal metastatic models. Herein we developed a biomimetic microfluidic model to study cancer metastasis. Primary cells isolated from different organs were cultured on the microlfuidic model to represent individual organs. Breast and salivary gland cancer cells were driven to flow over primary cell culture chambers, mimicking dynamic adhesion of circulating tumor cells (CTCs) to endothelium in vivo. These flowing artificial CTCs showed different metastatic potentials to lung on the microfluidic model. The traditional nude mouse model of lung metastasis was performed to investigate the physiological similarity of the microfluidic model to animal models. It was found that the metastatic potential of different cancer cells assessed by the microfluidic model was in agreement with that assessed by the nude mouse model. Furthermore, it was demonstrated that the metastatic inhibitor AMD3100 inhibited lung metastasis effectively in both the microfluidic model and the nude mouse model. Then the microfluidic model was used to mimick liver and bone metastasis of CTCs and confirm the potential for research of multiple-organ metastasis. Thus, the metastasis of CTCs to different organs was reconstituted on the microfluidic model. It may expand the capabilities of traditional cell culture models, providing a low-cost, time-saving, and rapid alternative to animal models.

On demand nanoliter-scale microfluidic droplet generation, injection, and mixing using a passive microfluidic device

PubMed Central

Tangen, Uwe; Sharma, Abhishek

2015-01-01

We here present and characterize a programmable nanoliter scale droplet-on-demand device that can be used separately or readily integrated into low cost single layer rapid prototyping microfluidic systems for a wide range of user applications. The passive microfluidic device allows external (off-the-shelf) electronically controlled pinch valves to program the delivery of nanoliter scale aqueous droplets from up to 9 different inputs to a central outlet channel. The inputs can be either continuous aqueous fluid streams or microliter scale aqueous plugs embedded in a carrier fluid, in which case the number of effective input solutions that can be employed in an experiment is no longer strongly constrained (100 s–1000 s). Both nanoliter droplet sequencing output and nanoliter-scale droplet mixing are reported with this device. Optimization of the geometry and pressure relationships in the device was achieved in several hardware iterations with the support of open source microfluidic simulation software and equivalent circuit models. The requisite modular control of pressure relationships within the device is accomplished using hydrodynamic barriers and matched resistance channels with three different channel heights, custom parallel reversible microfluidic I/O connections, low dead-volume pinch valves, and a simply adjustable array of external screw valves. Programmable sequences of droplet mixes or chains of droplets can be achieved with the device at low Hz frequencies, limited by device elasticity, and could be further enhanced by valve integration. The chip has already found use in the characterization of droplet bunching during export and the synthesis of a DNA library. PMID:25759752

On demand nanoliter-scale microfluidic droplet generation, injection, and mixing using a passive microfluidic device.

PubMed

Tangen, Uwe; Sharma, Abhishek; Wagler, Patrick; McCaskill, John S

2015-01-01

We here present and characterize a programmable nanoliter scale droplet-on-demand device that can be used separately or readily integrated into low cost single layer rapid prototyping microfluidic systems for a wide range of user applications. The passive microfluidic device allows external (off-the-shelf) electronically controlled pinch valves to program the delivery of nanoliter scale aqueous droplets from up to 9 different inputs to a central outlet channel. The inputs can be either continuous aqueous fluid streams or microliter scale aqueous plugs embedded in a carrier fluid, in which case the number of effective input solutions that can be employed in an experiment is no longer strongly constrained (100 s-1000 s). Both nanoliter droplet sequencing output and nanoliter-scale droplet mixing are reported with this device. Optimization of the geometry and pressure relationships in the device was achieved in several hardware iterations with the support of open source microfluidic simulation software and equivalent circuit models. The requisite modular control of pressure relationships within the device is accomplished using hydrodynamic barriers and matched resistance channels with three different channel heights, custom parallel reversible microfluidic I/O connections, low dead-volume pinch valves, and a simply adjustable array of external screw valves. Programmable sequences of droplet mixes or chains of droplets can be achieved with the device at low Hz frequencies, limited by device elasticity, and could be further enhanced by valve integration. The chip has already found use in the characterization of droplet bunching during export and the synthesis of a DNA library.

Open-top selective plane illumination microscope for conventionally mounted specimens.

PubMed

McGorty, Ryan; Liu, Harrison; Kamiyama, Daichi; Dong, Zhiqiang; Guo, Su; Huang, Bo

2015-06-15

We have developed a new open-top selective plane illumination microscope (SPIM) compatible with microfluidic devices, multi-well plates, and other sample formats used in conventional inverted microscopy. Its key element is a water prism that compensates for the aberrations introduced when imaging at 45 degrees through a coverglass. We have demonstrated its unique high-content imaging capability by recording Drosophila embryo development in environmentally-controlled microfluidic channels and imaging zebrafish embryos in 96-well plates. We have also shown the imaging of C. elegans and moving Drosophila larvae on coverslips.

PNNL: Climate Modelling

Science.gov Websites

Runs [ Open Access : Password Protected ] CESM Development CESM Runs [ Open Access : Password Protected ] WRF Development WRF Runs [ Open Access : Password Protected ] Climate Modeling Home Projects Links Literature Manuscripts Publications Polar Group Meeting (2012) ASGC Home ASGC Jobs Web Calendar Wiki Internal

Publishing in open access era: focus on respiratory journals

PubMed Central

Xu, Dingyao; Zhong, Xiyao; Li, Li; Ling, Qibo; Bu, Zhaode

2014-01-01

We have entered an open access publishing era. The impact and significance of open access is still under debate after two decades of evolution. Open access journals benefit researchers and the general public by promoting visibility, sharing and communicating. Non-mainstream journals should turn the challenge of open access into opportunity of presenting best research articles to the global readership. Open access journals need to optimize their business models to promote the healthy and continuous development. PMID:24822120

Publishing in open access era: focus on respiratory journals.

PubMed

Dai, Ni; Xu, Dingyao; Zhong, Xiyao; Li, Li; Ling, Qibo; Bu, Zhaode

2014-05-01

We have entered an open access publishing era. The impact and significance of open access is still under debate after two decades of evolution. Open access journals benefit researchers and the general public by promoting visibility, sharing and communicating. Non-mainstream journals should turn the challenge of open access into opportunity of presenting best research articles to the global readership. Open access journals need to optimize their business models to promote the healthy and continuous development.

Open Access in the Natural and Social Sciences: The Correspondence of Innovative Moves to Enhance Access, Inclusion and Impact in Scholarly Communication

ERIC Educational Resources Information Center

Armbruster, Chris

2008-01-01

Online, open access is the superior model for scholarly communication. A variety of scientific communities in physics, the life sciences and economics have gone furthest in innovating their scholarly communication through open access, enhancing accessibility for scientists, students and the interested public. Open access enjoys a comparative…

Global review of open access risk assessment software packages valid for global or continental scale analysis

NASA Astrophysics Data System (ADS)

Daniell, James; Simpson, Alanna; Gunasekara, Rashmin; Baca, Abigail; Schaefer, Andreas; Ishizawa, Oscar; Murnane, Rick; Tijssen, Annegien; Deparday, Vivien; Forni, Marc; Himmelfarb, Anne; Leder, Jan

2015-04-01

Over the past few decades, a plethora of open access software packages for the calculation of earthquake, volcanic, tsunami, storm surge, wind and flood have been produced globally. As part of the World Bank GFDRR Review released at the Understanding Risk 2014 Conference, over 80 such open access risk assessment software packages were examined. Commercial software was not considered in the evaluation. A preliminary analysis was used to determine whether the 80 models were currently supported and if they were open access. This process was used to select a subset of 31 models that include 8 earthquake models, 4 cyclone models, 11 flood models, and 8 storm surge/tsunami models for more detailed analysis. By using multi-criteria analysis (MCDA) and simple descriptions of the software uses, the review allows users to select a few relevant software packages for their own testing and development. The detailed analysis evaluated the models on the basis of over 100 criteria and provides a synopsis of available open access natural hazard risk modelling tools. In addition, volcano software packages have since been added making the compendium of risk software tools in excess of 100. There has been a huge increase in the quality and availability of open access/source software over the past few years. For example, private entities such as Deltares now have an open source policy regarding some flood models (NGHS). In addition, leaders in developing risk models in the public sector, such as Geoscience Australia (EQRM, TCRM, TsuDAT, AnuGA) or CAPRA (ERN-Flood, Hurricane, CRISIS2007 etc.), are launching and/or helping many other initiatives. As we achieve greater interoperability between modelling tools, we will also achieve a future wherein different open source and open access modelling tools will be increasingly connected and adapted towards unified multi-risk model platforms and highly customised solutions. It was seen that many software tools could be improved by enabling user-defined exposure and vulnerability. Without this function, many tools can only be used regionally and not at global or continental scale. It is becoming increasingly easy to use multiple packages for a single region and/or hazard to characterize the uncertainty in the risk, or use as checks for the sensitivities in the analysis. There is a potential for valuable synergy between existing software. A number of open source software packages could be combined to generate a multi-risk model with multiple views of a hazard. This extensive review has simply attempted to provide a platform for dialogue between all open source and open access software packages and to hopefully inspire collaboration between developers, given the great work done by all open access and open source developers.

Soft tubular microfluidics for 2D and 3D applications

PubMed Central

Xi, Wang; Kong, Fang; Yeo, Joo Chuan; Yu, Longteng; Sonam, Surabhi; Dao, Ming; Gong, Xiaobo; Lim, Chwee Teck

2017-01-01

Microfluidics has been the key component for many applications, including biomedical devices, chemical processors, microactuators, and even wearable devices. This technology relies on soft lithography fabrication which requires cleanroom facilities. Although popular, this method is expensive and labor-intensive. Furthermore, current conventional microfluidic chips precludes reconfiguration, making reiterations in design very time-consuming and costly. To address these intrinsic drawbacks of microfabrication, we present an alternative solution for the rapid prototyping of microfluidic elements such as microtubes, valves, and pumps. In addition, we demonstrate how microtubes with channels of various lengths and cross-sections can be attached modularly into 2D and 3D microfluidic systems for functional applications. We introduce a facile method of fabricating elastomeric microtubes as the basic building blocks for microfluidic devices. These microtubes are transparent, biocompatible, highly deformable, and customizable to various sizes and cross-sectional geometries. By configuring the microtubes into deterministic geometry, we enable rapid, low-cost formation of microfluidic assemblies without compromising their precision and functionality. We demonstrate configurable 2D and 3D microfluidic systems for applications in different domains. These include microparticle sorting, microdroplet generation, biocatalytic micromotor, triboelectric sensor, and even wearable sensing. Our approach, termed soft tubular microfluidics, provides a simple, cheaper, and faster solution for users lacking proficiency and access to cleanroom facilities to design and rapidly construct microfluidic devices for their various applications and needs. PMID:28923968

Soft tubular microfluidics for 2D and 3D applications

NASA Astrophysics Data System (ADS)

Xi, Wang; Kong, Fang; Yeo, Joo Chuan; Yu, Longteng; Sonam, Surabhi; Dao, Ming; Gong, Xiaobo; Teck Lim, Chwee

2017-10-01

Microfluidics has been the key component for many applications, including biomedical devices, chemical processors, microactuators, and even wearable devices. This technology relies on soft lithography fabrication which requires cleanroom facilities. Although popular, this method is expensive and labor-intensive. Furthermore, current conventional microfluidic chips precludes reconfiguration, making reiterations in design very time-consuming and costly. To address these intrinsic drawbacks of microfabrication, we present an alternative solution for the rapid prototyping of microfluidic elements such as microtubes, valves, and pumps. In addition, we demonstrate how microtubes with channels of various lengths and cross-sections can be attached modularly into 2D and 3D microfluidic systems for functional applications. We introduce a facile method of fabricating elastomeric microtubes as the basic building blocks for microfluidic devices. These microtubes are transparent, biocompatible, highly deformable, and customizable to various sizes and cross-sectional geometries. By configuring the microtubes into deterministic geometry, we enable rapid, low-cost formation of microfluidic assemblies without compromising their precision and functionality. We demonstrate configurable 2D and 3D microfluidic systems for applications in different domains. These include microparticle sorting, microdroplet generation, biocatalytic micromotor, triboelectric sensor, and even wearable sensing. Our approach, termed soft tubular microfluidics, provides a simple, cheaper, and faster solution for users lacking proficiency and access to cleanroom facilities to design and rapidly construct microfluidic devices for their various applications and needs.

Enhanced biocompatibility of neural probes by integrating microstructures and delivering anti-inflammatory agents via microfluidic channels

NASA Astrophysics Data System (ADS)

Liu, Bin; Kim, Eric; Meggo, Anika; Gandhi, Sachin; Luo, Hao; Kallakuri, Srinivas; Xu, Yong; Zhang, Jinsheng

2017-04-01

Objective. Biocompatibility is a major issue for chronic neural implants, involving inflammatory and wound healing responses of neurons and glial cells. To enhance biocompatibility, we developed silicon-parylene hybrid neural probes with open architecture electrodes, microfluidic channels and a reservoir for drug delivery to suppress tissue responses. Approach. We chronically implanted our neural probes in the rat auditory cortex and investigated (1) whether open architecture electrode reduces inflammatory reaction by measuring glial responses; and (2) whether delivery of antibiotic minocycline reduces inflammatory and tissue reaction. Four weeks after implantation, immunostaining for glial fibrillary acid protein (astrocyte marker) and ionizing calcium-binding adaptor molecule 1 (macrophages/microglia cell marker) were conducted to identify immunoreactive astrocyte and microglial cells, and to determine the extent of astrocytes and microglial cell reaction/activation. A comparison was made between using traditional solid-surface electrodes and newly-designed electrodes with open architecture, as well as between deliveries of minocycline and artificial cerebral-spinal fluid diffused through microfluidic channels. Main results. The new probes with integrated micro-structures induced minimal tissue reaction compared to traditional electrodes at 4 weeks after implantation. Microcycline delivered through integrated microfluidic channels reduced tissue response as indicated by decreased microglial reaction around the neural probes implanted. Significance. The new design will help enhance the long-term stability of the implantable devices.

Microfluidics and microbial engineering.

PubMed

Kou, Songzi; Cheng, Danhui; Sun, Fei; Hsing, I-Ming

2016-02-07

The combination of microbial engineering and microfluidics is synergistic in nature. For example, microfluidics is benefiting from the outcome of microbial engineering and many reported point-of-care microfluidic devices employ engineered microbes as functional parts for the microsystems. In addition, microbial engineering is facilitated by various microfluidic techniques, due to their inherent strength in high-throughput screening and miniaturization. In this review article, we firstly examine the applications of engineered microbes for toxicity detection, biosensing, and motion generation in microfluidic platforms. Secondly, we look into how microfluidic technologies facilitate the upstream and downstream processes of microbial engineering, including DNA recombination, transformation, target microbe selection, mutant characterization, and microbial function analysis. Thirdly, we highlight an emerging concept in microbial engineering, namely, microbial consortium engineering, where the behavior of a multicultural microbial community rather than that of a single cell/species is delineated. Integrating the disciplines of microfluidics and microbial engineering opens up many new opportunities, for example in diagnostics, engineering of microbial motors, development of portable devices for genetics, high throughput characterization of genetic mutants, isolation and identification of rare/unculturable microbial species, single-cell analysis with high spatio-temporal resolution, and exploration of natural microbial communities.

Multiphase flows with digital and traditional microfluidics

NASA Astrophysics Data System (ADS)

Nilsson, Michael A.

Multi-phase fluid systems are an important concept in fluid mechanics, seen every day in how fluids interact with solids, gases, and other fluids in many industrial, medical, agricultural, and other regimes. In this thesis, the development of a two-dimensional digital microfluidic device is presented, followed by the development of a two-phase microfluidic diagnostic tool designed to simulate sandstone geometries in oil reservoirs. In both instances, it is possible to take advantage of the physics involved in multiphase flows to affect positive outcomes in both. In order to make an effective droplet-based digital microfluidic device, one must be able to precisely control a number of key processes including droplet positioning, motion, coalescence, mixing, and sorting. For planar or open microfluidic devices, many of these processes have yet to be demonstrated. A suitable platform for an open system is a superhydrophobic surface, as suface characteristics are critical. Great efforts have been spent over the last decade developing hydrophobic surfaces exhibiting very large contact angles with water, and which allow for high droplet mobility. We demonstrate that sanding Teflon can produce superhydrophobic surfaces with advancing contact angles of up to 151° and contact angle hysteresis of less than 4°. We use these surfaces to characterize droplet coalescence, mixing, motion, deflection, positioning, and sorting. This research culminates with the presentation of two digital microfluidic devices: a droplet reactor/analyzer and a droplet sorter. As global energy usage increases, maximizing oil recovery from known reserves becomes a crucial multiphase challenge in order to meet the rising demand. This thesis presents the development of a microfluidic sandstone platform capable of quickly and inexpensively testing the performance of fluids with different rheological properties on the recovery of oil. Specifically, these microfluidic devices are utilized to examine how shear-thinning, shear-thickening, and viscoelastic fluids affect oil recovery. This work begins by looking at oil displacement from a microfluidic sandstone device, then investigates small-scale oil recovery from a single pore, and finally investigates oil displacement from larger scale, more complex microfluidic sandstone devices of varying permeability. The results demonstrate that with careful fluid design, it is possible to outperform current commercial additives using the patent-pending fluid we developed. Furthermore, the resulting microfluidic sandstone devices can reduce the time and cost of developing and testing of current and new enhanced oil recovery fluids.

Microprocessor-based integration of microfluidic control for the implementation of automated sensor monitoring and multithreaded optimization algorithms.

PubMed

Ezra, Elishai; Maor, Idan; Bavli, Danny; Shalom, Itai; Levy, Gahl; Prill, Sebastian; Jaeger, Magnus S; Nahmias, Yaakov

2015-08-01

Microfluidic applications range from combinatorial synthesis to high throughput screening, with platforms integrating analog perfusion components, digitally controlled micro-valves and a range of sensors that demand a variety of communication protocols. Currently, discrete control units are used to regulate and monitor each component, resulting in scattered control interfaces that limit data integration and synchronization. Here, we present a microprocessor-based control unit, utilizing the MS Gadgeteer open framework that integrates all aspects of microfluidics through a high-current electronic circuit that supports and synchronizes digital and analog signals for perfusion components, pressure elements, and arbitrary sensor communication protocols using a plug-and-play interface. The control unit supports an integrated touch screen and TCP/IP interface that provides local and remote control of flow and data acquisition. To establish the ability of our control unit to integrate and synchronize complex microfluidic circuits we developed an equi-pressure combinatorial mixer. We demonstrate the generation of complex perfusion sequences, allowing the automated sampling, washing, and calibrating of an electrochemical lactate sensor continuously monitoring hepatocyte viability following exposure to the pesticide rotenone. Importantly, integration of an optical sensor allowed us to implement automated optimization protocols that require different computational challenges including: prioritized data structures in a genetic algorithm, distributed computational efforts in multiple-hill climbing searches and real-time realization of probabilistic models in simulated annealing. Our system offers a comprehensive solution for establishing optimization protocols and perfusion sequences in complex microfluidic circuits.

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.

CMOS Enabled Microfluidic Systems for Healthcare Based Applications.

PubMed

Khan, Sherjeel M; Gumus, Abdurrahman; Nassar, Joanna M; Hussain, Muhammad M

2018-04-01

With the increased global population, it is more important than ever to expand accessibility to affordable personalized healthcare. In this context, a seamless integration of microfluidic technology for bioanalysis and drug delivery and complementary metal oxide semiconductor (CMOS) technology enabled data-management circuitry is critical. Therefore, here, the fundamentals, integration aspects, and applications of CMOS-enabled microfluidic systems for affordable personalized healthcare systems are presented. Critical components, like sensors, actuators, and their fabrication and packaging, are discussed and reviewed in detail. With the emergence of the Internet-of-Things and the upcoming Internet-of-Everything for a people-process-data-device connected world, now is the time to take CMOS-enabled microfluidics technology to as many people as possible. There is enormous potential for microfluidic technologies in affordable healthcare for everyone, and CMOS technology will play a major role in making that happen. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rapid mask prototyping for microfluidics.

PubMed

Maisonneuve, B G C; Honegger, T; Cordeiro, J; Lecarme, O; Thiry, T; Fuard, D; Berton, K; Picard, E; Zelsmann, M; Peyrade, D

2016-03-01

With the rise of microfluidics for the past decade, there has come an ever more pressing need for a low-cost and rapid prototyping technology, especially for research and education purposes. In this article, we report a rapid prototyping process of chromed masks for various microfluidic applications. The process takes place out of a clean room, uses a commercially available video-projector, and can be completed in less than half an hour. We quantify the ranges of fields of view and of resolutions accessible through this video-projection system and report the fabrication of critical microfluidic components (junctions, straight channels, and curved channels). To exemplify the process, three common devices are produced using this method: a droplet generation device, a gradient generation device, and a neuro-engineering oriented device. The neuro-engineering oriented device is a compartmentalized microfluidic chip, and therefore, required the production and the precise alignment of two different masks.

Rapid mask prototyping for microfluidics

PubMed Central

Maisonneuve, B. G. C.; Honegger, T.; Cordeiro, J.; Lecarme, O.; Thiry, T.; Fuard, D.; Berton, K.; Picard, E.; Zelsmann, M.; Peyrade, D.

2016-01-01

With the rise of microfluidics for the past decade, there has come an ever more pressing need for a low-cost and rapid prototyping technology, especially for research and education purposes. In this article, we report a rapid prototyping process of chromed masks for various microfluidic applications. The process takes place out of a clean room, uses a commercially available video-projector, and can be completed in less than half an hour. We quantify the ranges of fields of view and of resolutions accessible through this video-projection system and report the fabrication of critical microfluidic components (junctions, straight channels, and curved channels). To exemplify the process, three common devices are produced using this method: a droplet generation device, a gradient generation device, and a neuro-engineering oriented device. The neuro-engineering oriented device is a compartmentalized microfluidic chip, and therefore, required the production and the precise alignment of two different masks. PMID:27014396

Microfluidic and nanofluidic phase behaviour characterization for industrial CO2, oil and gas.

PubMed

Bao, Bo; Riordon, Jason; Mostowfi, Farshid; Sinton, David

2017-08-08

Microfluidic systems that leverage unique micro-scale phenomena have been developed to provide rapid, accurate and robust analysis, predominantly for biomedical applications. These attributes, in addition to the ability to access high temperatures and pressures, have motivated recent expanded applications in phase measurements relevant to industrial CO 2 , oil and gas applications. We here present a comprehensive review of this exciting new field, separating microfluidic and nanofluidic approaches. Microfluidics is practical, and provides similar phase properties analysis to established bulk methods with advantages in speed, control and sample size. Nanofluidic phase behaviour can deviate from bulk measurements, which is of particular relevance to emerging unconventional oil and gas production from nanoporous shale. In short, microfluidics offers a practical, compelling replacement of current bulk phase measurement systems, whereas nanofluidics is not practical, but uniquely provides insight into phase change phenomena at nanoscales. Challenges, trends and opportunities for phase measurements at both scales are highlighted.

Dielectrophoresis-based microfluidic platforms for cancer diagnostics.

PubMed

Chan, Jun Yuan; Ahmad Kayani, Aminuddin Bin; Md Ali, Mohd Anuar; Kok, Chee Kuang; Yeop Majlis, Burhanuddin; Hoe, Susan Ling Ling; Marzuki, Marini; Khoo, Alan Soo-Beng; Ostrikov, Kostya Ken; Ataur Rahman, Md; Sriram, Sharath

2018-01-01

The recent advancement of dielectrophoresis (DEP)-enabled microfluidic platforms is opening new opportunities for potential use in cancer disease diagnostics. DEP is advantageous because of its specificity, low cost, small sample volume requirement, and tuneable property for microfluidic platforms. These intrinsic advantages have made it especially suitable for developing microfluidic cancer diagnostic platforms. This review focuses on a comprehensive analysis of the recent developments of DEP enabled microfluidic platforms sorted according to the target cancer cell. Each study is critically analyzed, and the features of each platform, the performance, added functionality for clinical use, and the types of samples, used are discussed. We address the novelty of the techniques, strategies, and design configuration used in improving on existing technologies or previous studies. A summary of comparing the developmental extent of each study is made, and we conclude with a treatment of future trends and a brief summary.

Open access: changing global science publishing.

PubMed

Gasparyan, Armen Yuri; Ayvazyan, Lilit; Kitas, George D

2013-08-01

The article reflects on open access as a strategy of changing the quality of science communication globally. Successful examples of open-access journals are presented to highlight implications of archiving in open digital repositories for the quality and citability of research output. Advantages and downsides of gold, green, and hybrid models of open access operating in diverse scientific environments are described. It is assumed that open access is a global trend which influences the workflow in scholarly journals, changing their quality, credibility, and indexability.

Cost Effective Paper-Based Colorimetric Microfluidic Devices and Mobile Phone Camera Readers for the Classroom

ERIC Educational Resources Information Center

Koesdjojo, Myra T.; Pengpumkiat, Sumate; Wu, Yuanyuan; Boonloed, Anukul; Huynh, Daniel; Remcho, Thomas P.; Remcho, Vincent T.

2015-01-01

We have developed a simple and direct method to fabricate paper-based microfluidic devices that can be used for a wide range of colorimetric assay applications. With these devices, assays can be performed within minutes to allow for quantitative colorimetric analysis by use of a widely accessible iPhone camera and an RGB color reader application…

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.

Waste-to-energy conversion from a microfluidic device

NASA Astrophysics Data System (ADS)

López-González, B.; Jiménez-Valdés, R. J.; Moreno-Zuria, A.; Cuevas-Muñiz, F. M.; Ledesma-García, J.; García-Cordero, J. L.; Arriaga, L. G.

2017-08-01

This work reports the successful harvesting of energy from waste produced in a microfluidic device using a fuel cell. A miniaturized glucose air-breathing microfluidic fuel cell (ABμFFC) was designed, fabricated and tested with three different configurations according to their electrode nature: inorganic, hybrid and biofuel cell. Each ABμFFC was characterized using an ideal medium, with sterile cell culture medium, and with waste produced on a microfluidic device. The inorganic-ABμFFC exhibited the highest performance compared to the rest of the configurations. As a proof-of-concept, cancer cells were cultured on a microfluidic device and the consumed cell culture media (glucose concentration <11 mM) was used as an energy source without further treatment, into the inorganic-ABμFFC. The fuel cell generated a maximum total power of 5.2 μW, which is enough energy to power low-consumption microelectronic chips. This application demonstrates that the waste produced by microfluidic applications could be potentially scavenged to produce electrical energy. It also opens the possibility to develop truly energy self-sufficient portable devices.

Magnetic timing valves for fluid control in paper-based microfluidics.

PubMed

Li, Xiao; Zwanenburg, Philip; Liu, Xinyu

2013-07-07

Multi-step analytical tests, such as an enzyme-linked immunosorbent assay (ELISA), require delivery of multiple fluids into a reaction zone and counting the incubation time at different steps. This paper presents a new type of paper-based magnetic valves that can count the time and turn on or off a fluidic flow accordingly, enabling timed fluid control in paper-based microfluidics. The timing capability of these valves is realized using a paper timing channel with an ionic resistor, which can detect the event of a solution flowing through the resistor and trigger an electromagnet (through a simple circuit) to open or close a paper cantilever valve. Based on this principle, we developed normally-open and normally-closed valves with a timing period up to 30.3 ± 2.1 min (sufficient for an ELISA on paper-based platforms). Using the normally-open valve, we performed an enzyme-based colorimetric reaction commonly used for signal readout of ELISAs, which requires a timed delivery of an enzyme substrate to a reaction zone. This design adds a new fluid-control component to the tool set for developing paper-based microfluidic devices, and has the potential to improve the user-friendliness of these devices.

A compact model for electroosmotic flows in microfluidic devices

NASA Astrophysics Data System (ADS)

Qiao, R.; Aluru, N. R.

2002-09-01

A compact model to compute flow rate and pressure in microfluidic devices is presented. The microfluidic flow can be driven by either an applied electric field or a combined electric field and pressure gradient. A step change in the ζ-potential on a channel wall is treated by a pressure source in the compact model. The pressure source is obtained from the pressure Poisson equation and conservation of mass principle. In the proposed compact model, the complex fluidic network is simplified by an electrical circuit. The compact model can predict the flow rate, pressure distribution and other basic characteristics in microfluidic channels quickly with good accuracy when compared to detailed numerical simulation. Using the compact model, fluidic mixing and dispersion control are studied in a complex microfluidic network.

Publish or perish, and pay--the new paradigm of open-access journals.

PubMed

Tzarnas, Stephanie; Tzarnas, Chris D

2015-01-01

The new open-access journal business model is changing the publication landscape and residents and junior faculty should be aware of these changes. A national survey of surgery program directors and residents was performed. Open-access journals have been growing over the past decade, and many traditional printed journals are also sponsoring open-access options (the hybrid model) for accepted articles. Authors need to be aware of the new publishing paradigm and potential costs involved in publishing their work. Copyright © 2014 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Towards non- and minimally instrumented, microfluidics-based diagnostic devices†

PubMed Central

Weigl, Bernhard; Domingo, Gonzalo; LaBarre, Paul; Gerlach, Jay

2009-01-01

In many health care settings, it is uneconomical, impractical, or unaffordable to maintain and access a fully equipped diagnostics laboratory. Examples include home health care, developing-country health care, and emergency situations in which first responders are dealing with pandemics or biowarfare agent release. In those settings, fully disposable diagnostic devices that require no instrument support, reagent, or significant training are well suited. Although the only such technology to have found widespread adoption so far is the immunochromatographic rapid assay strip test, microfluidics holds promise to expand the range of assay technologies that can be performed in formats similar to that of a strip test. In this paper, we review progress toward development of disposable, low-cost, easy-to-use microfluidics-based diagnostics that require no instrument at all. We also present examples of microfluidic functional elements—including mixers, separators, and detectors—as well as complete microfluidic devices that function entirely without any moving parts and external power sources. PMID:19023463

3D-printed microfluidic automation.

PubMed

Au, Anthony K; Bhattacharjee, Nirveek; Horowitz, Lisa F; Chang, Tim C; Folch, Albert

2015-04-21

Microfluidic automation - the automated routing, dispensing, mixing, and/or separation of fluids through microchannels - generally remains a slowly-spreading technology because device fabrication requires sophisticated facilities and the technology's use demands expert operators. Integrating microfluidic automation in devices has involved specialized multi-layering and bonding approaches. Stereolithography is an assembly-free, 3D-printing technique that is emerging as an efficient alternative for rapid prototyping of biomedical devices. Here we describe fluidic valves and pumps that can be stereolithographically printed in optically-clear, biocompatible plastic and integrated within microfluidic devices at low cost. User-friendly fluid automation devices can be printed and used by non-engineers as replacement for costly robotic pipettors or tedious manual pipetting. Engineers can manipulate the designs as digital modules into new devices of expanded functionality. Printing these devices only requires the digital file and electronic access to a printer.

Femtosecond Laser Fabrication of Monolithically Integrated Microfluidic Sensors in Glass

PubMed Central

He, Fei; Liao, Yang; Lin, Jintian; Song, Jiangxin; Qiao, Lingling; Cheng, Ya; Sugioka, Koji

2014-01-01

Femtosecond lasers have revolutionized the processing of materials, since their ultrashort pulse width and extremely high peak intensity allows high-quality micro- and nanofabrication of three-dimensional (3D) structures. This unique capability opens up a new route for fabrication of microfluidic sensors for biochemical applications. The present paper presents a comprehensive review of recent advancements in femtosecond laser processing of glass for a variety of microfluidic sensor applications. These include 3D integration of micro-/nanofluidic, optofluidic, electrofluidic, surface-enhanced Raman-scattering devices, in addition to fabrication of devices for microfluidic bioassays and lab-on-fiber sensors. This paper describes the unique characteristics of femtosecond laser processing and the basic concepts involved in femtosecond laser direct writing. Advanced spatiotemporal beam shaping methods are also discussed. Typical examples of microfluidic sensors fabricated using femtosecond lasers are then highlighted, and their applications in chemical and biological sensing are described. Finally, a summary of the technology is given and the outlook for further developments in this field is considered. PMID:25330047

Immobilization of pH-sensitive CdTe Quantum Dots in a Poly(acrylate) Hydrogel for Microfluidic Applications

NASA Astrophysics Data System (ADS)

Franke, M.; Leubner, S.; Dubavik, A.; George, A.; Savchenko, T.; Pini, C.; Frank, P.; Melnikau, D.; Rakovich, Y.; Gaponik, N.; Eychmüller, A.; Richter, A.

2017-04-01

Microfluidic devices present the basis of modern life sciences and chemical information processing. To control the flow and to allow optical readout, a reliable sensor material that can be easily utilized for microfluidic systems is in demand. Here, we present a new optical readout system for pH sensing based on pH sensitive, photoluminescent glutathione capped cadmium telluride quantum dots that are covalently immobilized in a poly(acrylate) hydrogel. For an applicable pH sensing the generated hybrid material is integrated in a microfluidic sensor chip setup. The hybrid material not only allows in situ readout, but also possesses valve properties due to the swelling behavior of the poly(acrylate) hydrogel. In this work, the swelling property of the hybrid material is utilized in a microfluidic valve seat, where a valve opening process is demonstrated by a fluid flow change and in situ monitored by photoluminescence quenching. This discrete photoluminescence detection (ON/OFF) of the fluid flow change (OFF/ON) enables upcoming chemical information processing.

Micro-Fluidic Device for Drug Delivery

NASA Technical Reports Server (NTRS)

Beebe, David J. (Inventor); Eddington, David T. (Inventor); MacDonald, Michael J. (Inventor); Mensing, Glennys A. (Inventor)

2014-01-01

A microfluidic device is provided for delivering a drug to an individual. The microfluidic device includes a body that defines a reservoir for receiving the drug therein. A valve interconnects the reservoir to an output needle that is insertable into the skin of an individual. A pressure source urges the drug from the reservoir toward the needle. The valve is movable between a closed position preventing the flow of the drug from the reservoir to the output needle and an open position allowing for the flow of the drug from the reservoir to the output needle in response to a predetermined condition in the physiological fluids of the individual.

Microfluidic device for drug delivery

NASA Technical Reports Server (NTRS)

MacDonald, Michael J. (Inventor); Eddington, David T. (Inventor); Beebe, David J. (Inventor); Mensing, Glennys A. (Inventor)

2010-01-01

A microfluidic device is provided for delivering a drug to an individual. The microfluidic device includes a body that defines a reservoir for receiving the drug therein. A valve interconnects the reservoir to an output needle that is insertable into the skin of an individual. A pressure source urges the drug from the reservoir toward the needle. The valve is movable between a closed position preventing the flow of the drug from the reservoir to the output needle and an open position allowing for the flow of the drug from the reservoir to the output needle in response to a predetermined condition in the physiological fluids of the individual.

Entrainment and Control of Bacterial Populations: An in Silico Study over a Spatially Extended Agent Based Model.

PubMed

Mina, Petros; Tsaneva-Atanasova, Krasimira; Bernardo, Mario di

2016-07-15

We extend a spatially explicit agent based model (ABM) developed previously to investigate entrainment and control of the emergent behavior of a population of synchronized oscillating cells in a microfluidic chamber. Unlike most of the work in models of control of cellular systems which focus on temporal changes, we model individual cells with spatial dependencies which may contribute to certain behavioral responses. We use the model to investigate the response of both open loop and closed loop strategies, such as proportional control (P-control), proportional-integral control (PI-control) and proportional-integral-derivative control (PID-control), to heterogeinities and growth in the cell population, variations of the control parameters and spatial effects such as diffusion in the spatially explicit setting of a microfluidic chamber setup. We show that, as expected from the theory of phase locking in dynamical systems, open loop control can only entrain the cell population in a subset of forcing periods, with a wide variety of dynamical behaviors obtained outside these regions of entrainment. Closed-loop control is shown instead to guarantee entrainment in a much wider region of control parameter space although presenting limitations when the population size increases over a certain threshold. In silico tracking experiments are also performed to validate the ability of classical control approaches to achieve other reference behaviors such as a desired constant output or a linearly varying one. All simulations are carried out in BSim, an advanced agent-based simulator of microbial population which is here extended ad hoc to include the effects of control strategies acting onto the population.

Note: Four-port microfluidic flow-cell with instant sample switching

NASA Astrophysics Data System (ADS)

MacGriff, Christopher A.; Wang, Shaopeng; Tao, Nongjian

2013-10-01

A simple device for high-speed microfluidic delivery of liquid samples to a surface plasmon resonance sensor surface is presented. The delivery platform is comprised of a four-port microfluidic cell, two ports serve as inlets for buffer and sample solutions, respectively, and a high-speed selector valve to control the alternate opening and closing of the two outlet ports. The time scale of buffer/sample switching (or sample injection rise and fall time) is on the order of milliseconds, thereby minimizing the opportunity for sample plug dispersion. The high rates of mass transport to and from the central microfluidic sensing region allow for SPR-based kinetic analysis of binding events with dissociation rate constants (kd) up to 130 s-1. The required sample volume is only 1 μL, allowing for minimal sample consumption during high-speed kinetic binding measurement.

Vacuum/compression valving (VCV) using parrafin-wax on a centrifugal microfluidic CD platform.

PubMed

Al-Faqheri, Wisam; Ibrahim, Fatimah; Thio, Tzer Hwai Gilbert; Moebius, Jacob; Joseph, Karunan; Arof, Hamzah; Madou, Marc

2013-01-01

This paper introduces novel vacuum/compression valves (VCVs) utilizing paraffin wax. A VCV is implemented by sealing the venting channel/hole with wax plugs (for normally-closed valve), or to be sealed by wax (for normally-open valve), and is activated by localized heating on the CD surface. We demonstrate that the VCV provides the advantages of avoiding unnecessary heating of the sample/reagents in the diagnostic process, allowing for vacuum sealing of the CD, and clear separation of the paraffin wax from the sample/reagents in the microfluidic process. As a proof of concept, the microfluidic processes of liquid flow switching and liquid metering is demonstrated with the VCV. Results show that the VCV lowers the required spinning frequency to perform the microfluidic processes with high accuracy and ease of control.

Vacuum/Compression Valving (VCV) Using Parrafin-Wax on a Centrifugal Microfluidic CD Platform

PubMed Central

Al-Faqheri, Wisam; Ibrahim, Fatimah; Thio, Tzer Hwai Gilbert; Moebius, Jacob; Joseph, Karunan; Arof, Hamzah; Madou, Marc

2013-01-01

This paper introduces novel vacuum/compression valves (VCVs) utilizing paraffin wax. A VCV is implemented by sealing the venting channel/hole with wax plugs (for normally-closed valve), or to be sealed by wax (for normally-open valve), and is activated by localized heating on the CD surface. We demonstrate that the VCV provides the advantages of avoiding unnecessary heating of the sample/reagents in the diagnostic process, allowing for vacuum sealing of the CD, and clear separation of the paraffin wax from the sample/reagents in the microfluidic process. As a proof of concept, the microfluidic processes of liquid flow switching and liquid metering is demonstrated with the VCV. Results show that the VCV lowers the required spinning frequency to perform the microfluidic processes with high accuracy and ease of control. PMID:23505528

Principles, Techniques, and Applications of Tissue Microfluidics

NASA Technical Reports Server (NTRS)

Wade, Lawrence A.; Kartalov, Emil P.; Shibata, Darryl; Taylor, Clive

2011-01-01

The principle of tissue microfluidics and its resultant techniques has been applied to cell analysis. Building microfluidics to suit a particular tissue sample would allow the rapid, reliable, inexpensive, highly parallelized, selective extraction of chosen regions of tissue for purposes of further biochemical analysis. Furthermore, the applicability of the techniques ranges beyond the described pathology application. For example, they would also allow the posing and successful answering of new sets of questions in many areas of fundamental research. The proposed integration of microfluidic techniques and tissue slice samples is called tissue microfluidics because it molds the microfluidic architectures in accordance with each particular structure of each specific tissue sample. Thus, microfluidics can be built around the tissues, following the tissue structure, or alternatively, the microfluidics can be adapted to the specific geometry of particular tissues. By contrast, the traditional approach is that microfluidic devices are structured in accordance with engineering considerations, while the biological components in applied devices are forced to comply with these engineering presets. The proposed principles represent a paradigm shift in microfluidic technology in three important ways: Microfluidic devices are to be directly integrated with, onto, or around tissue samples, in contrast to the conventional method of off-chip sample extraction followed by sample insertion in microfluidic devices. Architectural and operational principles of microfluidic devices are to be subordinated to suit specific tissue structure and needs, in contrast to the conventional method of building devices according to fluidic function alone and without regard to tissue structure. Sample acquisition from tissue is to be performed on-chip and is to be integrated with the diagnostic measurement within the same device, in contrast to the conventional method of off-chip sample prep and subsequent insertion into a diagnostic device. A more advanced form of tissue integration with microfluidics is tissue encapsulation, wherein the sample is completely encapsulated within a microfluidic device, to allow for full surface access. The immediate applications of these approaches lie with diagnostics of tissue slices and biopsy samples e.g. for cancer but the approaches would also be very useful in comparative genomics and other areas of fundamental research involving heterogeneous tissue samples.

Open Access Publishing in High-Energy Physics: the SCOAP3 Initiative

NASA Astrophysics Data System (ADS)

Mele, S.

2010-10-01

Scholarly communication in High-Energy Physics (HEP) shows traits very similar to Astronomy and Astrophysics: pervasiveness of Open Access to preprints through community-based services; a culture of openness and sharing among its researchers; a compact number of yearly articles published by a relatively small number of journals which are dear to the community. These aspects have led HEP to spearhead an innovative model for the transition of its scholarly publishing to Open Access. The Sponsoring Consortium for Open Access Publishing in Particle Physics (SCOAP) aims to be a central body to finance peer-review service rather than the purchase of access to information as in the traditional subscription model, with all articles in the discipline eventually available in Open Access. Sustainable funding to SCOAP would come from libraries, library consortia and HEP funding agencies, through a re-direction of funds currently spent for subscriptions to HEP journals. This paper presents the cultural and bibliometric factors at the roots of SCOAP and the current status of this worldwide initiative.

Droplet Velocity Measurement Based on Dielectric Layer Thickness Variation Using Digital Microfluidic Devices.

PubMed

Zulkepli, Siti Noor Idora Syafinaz; Hamid, Nor Hisham; Shukla, Vineeta

2018-05-08

In recent years, the number of interdisciplinary research works related to the development of miniaturized systems with integrated chemical and biological analyses is increasing. Digital microfluidic biochips (DMFBs) are one kind of miniaturized systems designed for conducting inexpensive, fast, convenient and reliable biochemical assay procedures focusing on basic scientific research and medical diagnostics. The role of a dielectric layer in the digital microfluidic biochips is prominent as it helps in actuating microliter droplets based on the electrowetting-on-dielectric (EWOD) technique. The advantages of using three different material layers of dielectric such as parafilm, polytetrafluoroethylene (PTFE) and ethylene tetrafluoroethylene (ETFE) were reported in the current work. A simple fabrication process of a digital microfluidic device was performed and good results were obtained. The threshold of the actuation voltage was determined for all dielectric materials of varying thicknesses. Additionally, the OpenDrop device was tested by utilizing a single-plate system to transport microliter droplets for a bioassay operation. With the newly proposed fabrication methods, these dielectric materials showed changes in contact angle and droplet velocity when the actuation voltage was applied. The threshold actuation voltage for the dielectric layers of 10⁻13 μm was 190 V for the open plate DMFBs.

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.

Microsphere integrated microfluidic disk: synergy of two techniques for rapid and ultrasensitive dengue detection.

PubMed

Hosseini, Samira; Aeinehvand, Mohammad M; Uddin, Shah M; Benzina, Abderazak; Rothan, Hussin A; Yusof, Rohana; Koole, Leo H; Madou, Marc J; Djordjevic, Ivan; Ibrahim, Fatimah

2015-11-09

The application of microfluidic devices in diagnostic systems is well-established in contemporary research. Large specific surface area of microspheres, on the other hand, has secured an important position for their use in bioanalytical assays. Herein, we report a combination of microspheres and microfluidic disk in a unique hybrid platform for highly sensitive and selective detection of dengue virus. Surface engineered polymethacrylate microspheres with carefully designed functional groups facilitate biorecognition in a multitude manner. In order to maximize the utility of the microspheres' specific surface area in biomolecular interaction, the microfluidic disk was equipped with a micromixing system. The mixing mechanism (microballoon mixing) enhances the number of molecular encounters between spheres and target analyte by accessing the entire sample volume more effectively, which subsequently results in signal amplification. Significant reduction of incubation time along with considerable lower detection limits were the prime motivations for the integration of microspheres inside the microfluidic disk. Lengthy incubations of routine analytical assays were reduced from 2 hours to 5 minutes while developed system successfully detected a few units of dengue virus. Obtained results make this hybrid microsphere-microfluidic approach to dengue detection a promising avenue for early detection of this fatal illness.

Pen-on-paper strategy for point-of-care testing: Rapid prototyping of fully written microfluidic biosensor.

PubMed

Li, Zedong; Li, Fei; Xing, Yue; Liu, Zhi; You, Minli; Li, Yingchun; Wen, Ting; Qu, Zhiguo; Ling Li, Xiao; Xu, Feng

2017-12-15

Paper-based microfluidic biosensors have recently attracted increasing attentions in point-of-care testing (POCT) territories benefiting from their affordable, accessible and eco-friendly features, where technologies for fabricating such biosensors are preferred to be equipment free, easy-to-operate and capable of rapid prototyping. In this work, we developed a pen-on-paper (PoP) strategy based on two custom-made pens, i.e., a wax pen and a conductive-ink pen, to fully write paper-based microfluidic biosensors through directly writing both microfluidic channels and electrodes. Particularly, the proposed wax pen is competent to realize one-step fabrication of wax channels on paper, as the melted wax penetrates into paper during writing process without any post-treatments. The practical applications of the fabricated paper-based microfluidic biosensors are demonstrated by both colorimetric detection of Salmonella typhimurium DNA with detection limit of 1nM and electrochemical measurement of glucose with detection limit of 1mM. The developed PoP strategy for making microfluidic biosensors on paper characterized by true simplicity, prominent portability and excellent capability for rapid prototyping shows promising prospect in POCT applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Microfluidic Foaming: A Powerful Tool for Tailoring the Morphological and Permeability Properties of Sponge-like Biopolymeric Scaffolds.

PubMed

Costantini, Marco; Colosi, Cristina; Jaroszewicz, Jakub; Tosato, Alessia; Święszkowski, Wojciech; Dentini, Mariella; Garstecki, Piotr; Barbetta, Andrea

2015-10-28

Ordered porous polymeric materials can be engineered to present highly ordered pore arrays and uniform and tunable pore size. These features prompted a number of applications in tissue engineering, generation of meta materials, and separation and purification of biomolecules and cells. Designing new and efficient vistas for the generation of ordered porous materials is an active area of research. Here we investigate the potential of microfluidic foaming within a flow-focusing (FF) geometry in producing 3D regular sponge-like polymeric matrices with tailored morphological and permeability properties. The challenge in using microfluidic systems for the generation of polymeric foams is in the high viscosity of the continuous phase. We demonstrate that as the viscosity of the aqueous solution increases, the accessible range of foam bubble fraction (Φb) and bubble diameter (Db) inside the microfluidic chip tend to narrow progressively. This effect limits the accessible range of geometric properties of the resulting materials. We further show that this problem can be rationally tackled by appropriate choice of the concentration of the polymer. We demonstrate that via such optimization, the microfluidic assisted synthesis of porous materials becomes a facile and versatile tool for generation of porous materials with a wide range of pore size and pore volume. Moreover, we demonstrate that the size of interconnects among pores-for a given value of the gas fraction-can be tailored through the variation of surfactant concentration. This, in turn, affects the permeability of the materials, a factor of key importance in flow-through applications and in tissue engineering.

Open access publishing and author-pays business models: a survey of authors' knowledge and perceptions

PubMed Central

Schroter, Sara; Tite, Leanne

2006-01-01

Objectives: We aimed to assess journal authors' current knowledge and perceptions of open access and author-pays publishing. Design: An electronic survey. Setting: Authors of research papers submitted to BMJ, Archives of Disease in Childhood, and Journal of Medical Genetics in 2004. Main outcome measures: Familiarity with and perceptions of open access and author-pays publishing. Results: 468/1113 (42%) responded. Prior to definitions being provided, 47% (222/468) and 38% (176/468) reported they were familiar with the terms `open access' and `author-pays' publishing, respectively. Some who did not at first recognize the terms, did claim to recognize them when they were defined. Only 10% (49/468) had submitted to an author-pays journal. Compared with non-open access subscription-based journals, 35% agreed that open access author-pays journals have a greater capacity to publish more content making it easier to get published, 27% thought they had lower impact factors, 31% thought they had faster and more timely publicaitons, and 46% agreed that people will think anyone can pay to get published. 55% (256/468) thought they would not continue to submit to their respective journal if it became open access and charged, largely because of the reputaiton of the journals. Half (54%, 255/468) said open access has `no impact' or was `low priority' in their submission decisions. Two-thirds (66%, 308/468) said they would prefer to submit to a non-open access subscription-based journal than an open access author-pays journal. Over half thought they would have to make a contribution or pay the full cost of an author charge (56%, 262/468). Conclusions: The survey yielded useful information about respondents' knowledge and perceptions of these publishing models. Authors have limited familiarity with the concept of open-access publishing and surrounding issues. Currently, open access policies have little impact on authors' decision of where to submit papers. PMID:16508053

Flow distribution in parallel microfluidic networks and its effect on concentration gradient

PubMed Central

Guermonprez, Cyprien; Michelin, Sébastien; Baroud, Charles N.

2015-01-01

The architecture of microfluidic networks can significantly impact the flow distribution within its different branches and thereby influence tracer transport within the network. In this paper, we study the flow rate distribution within a network of parallel microfluidic channels with a single input and single output, using a combination of theoretical modeling and microfluidic experiments. Within the ladder network, the flow rate distribution follows a U-shaped profile, with the highest flow rate occurring in the initial and final branches. The contrast with the central branches is controlled by a single dimensionless parameter, namely, the ratio of hydrodynamic resistance between the distribution channel and the side branches. This contrast in flow rates decreases when the resistance of the side branches increases relative to the resistance of the distribution channel. When the inlet flow is composed of two parallel streams, one of which transporting a diffusing species, a concentration variation is produced within the side branches of the network. The shape of this concentration gradient is fully determined by two dimensionless parameters: the ratio of resistances, which determines the flow rate distribution, and the Péclet number, which characterizes the relative speed of diffusion and advection. Depending on the values of these two control parameters, different distribution profiles can be obtained ranging from a flat profile to a step distribution of solute, with well-distributed gradients between these two limits. Our experimental results are in agreement with our numerical model predictions, based on a simplified 2D advection-diffusion problem. Finally, two possible applications of this work are presented: the first one combines the present design with self-digitization principle to encapsulate the controlled concentration in nanoliter chambers, while the second one extends the present design to create a continuous concentration gradient within an open flow chamber. PMID:26487905

Paper-based microfluidic devices by asymmetric calendaring

PubMed Central

Oyola-Reynoso, S.; Frankiewicz, C.; Chang, B.; Chen, J.; Bloch, J.-F.

2017-01-01

We report a simple, efficient, one-step, affordable method to produce open-channel paper-based microfluidic channels. One surface of a sheet of paper is selectively calendared, with concomitant hydrophobization, to create the microfluidic channel. Our method involves asymmetric mechanical modification of a paper surface using a rolling ball (ball-point pen) under a controlled amount of applied stress (σz) to ascertain that only one side is modified. A lubricating solvent (hexane) aids in the selective deformation. The lubricant also serves as a carrier for a perfluoroalkyl trichlorosilane allowing the channel to be made hydrophobic as it is formed. For brevity and clarity, we abbreviated this method as TACH (Targeted Asymmetric Calendaring and Hydrophobization). We demonstrate that TACH can be used to reliably produce channels of variable widths (size of the ball) and depths (number of passes), without affecting the nonworking surface of the paper. Using tomography, we demonstrate that these channels can vary from 10s to 100s of microns in diameter. The created hydrophobic barrier extends around the channel through wicking to ensure no leakages. We demonstrate, through modeling and fabrication, that flow properties of the resulting channels are analogous to conventional devices and are tunable based on associated dimensionless numbers. PMID:28798839

Full-angle tomographic phase microscopy of flowing quasi-spherical cells.

PubMed

Villone, Massimiliano M; Memmolo, Pasquale; Merola, Francesco; Mugnano, Martina; Miccio, Lisa; Maffettone, Pier Luca; Ferraro, Pietro

2017-12-19

We report a reliable full-angle tomographic phase microscopy (FA-TPM) method for flowing quasi-spherical cells along microfluidic channels. This method lies in a completely passive optical system, i.e. mechanical scanning or multi-direction probing of the sample is avoided. It exploits the engineered rolling of cells while they are flowing along a microfluidic channel. Here we demonstrate significant progress with respect to the state of the art of in-flow TPM by showing a general extension to cells having almost spherical shapes while they are flowing in suspension. In fact, the adopted strategy allows the accurate retrieval of rotation angles through a theoretical model of the cells' rotation in a dynamic microfluidic flow by matching it with phase-contrast images resulting from holographic reconstructions. So far, the proposed method is the first and the only one that permits to get in-flow TPM by probing the cells with full-angle, achieving accurate 3D refractive index mapping and the simplest optical setup, simultaneously. Proof of concept experiments were performed successfully on human breast adenocarcinoma MCF-7 cells, opening the way for the full characterization of circulating tumor cells (CTCs) in the new paradigm of liquid biopsy.

Analysis of FERC's Final EIS for Electricity Open Access & Recovery of Stranded Costs

EIA Publications

1996-01-01

Reviews the Final Environmental Impact Statement (FEIS) prepared by the Federal Energy Regulatory Commission for its electricity transmission system open access prepared in April 1996 and uses the National Energy Modeling System (NEMS) to analyze the open access rule (Orders 888 and 889).

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.

3D-Printed Microfluidic Automation

PubMed Central

Au, Anthony K.; Bhattacharjee, Nirveek; Horowitz, Lisa F.; Chang, Tim C.; Folch, Albert

2015-01-01

Microfluidic automation – the automated routing, dispensing, mixing, and/or separation of fluids through microchannels – generally remains a slowly-spreading technology because device fabrication requires sophisticated facilities and the technology’s use demands expert operators. Integrating microfluidic automation in devices has involved specialized multi-layering and bonding approaches. Stereolithography is an assembly-free, 3D-printing technique that is emerging as an efficient alternative for rapid prototyping of biomedical devices. Here we describe fluidic valves and pumps that can be stereolithographically printed in optically-clear, biocompatible plastic and integrated within microfluidic devices at low cost. User-friendly fluid automation devices can be printed and used by non-engineers as replacement for costly robotic pipettors or tedious manual pipetting. Engineers can manipulate the designs as digital modules into new devices of expanded functionality. Printing these devices only requires the digital file and electronic access to a printer. PMID:25738695

Recent advancements in ion concentration polarization.

PubMed

Li, Min; Anand, Robbyn K

2016-06-21

In this minireview, we discuss advancements in ion concentration polarization (ICP)-based preconcentration, separation, desalination, and dielectrophoresis that have been made over the past three years. ICP as a means of controlling the distribution of the ions and electric field in a microfluidic device has rapidly expanded its areas of application. Recent advancements have focused on the development of ion-permselective materials with tunable dimensions and surface chemistry, adaptation to paper microfluidics, higher-throughput device geometries, and coupling ICP with other separation (isotachophoresis and dielectrophoresis) and fluidic (valve and droplet microfluidic) strategies. These studies have made great strides toward solving real-world problems such as low-cost and rapid analysis, accessible desalination technology, and single-cell research tools.

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

An OpenStudio Measure is a script that can manipulate an OpenStudio model and associated data to apply energy conservation measures (ECMs), run supplemental simulations, or visualize simulation results. The OpenStudio software development kit (SDK) and accessibility of the Ruby scripting language makes measure authorship accessible to both software developers and energy modelers. This paper discusses the life cycle of an OpenStudio Measure from development, testing, and distribution, to application.

Automated centrifugal-microfluidic platform for DNA purification using laser burst valve and coriolis effect.

PubMed

Choi, Min-Seong; Yoo, Jae-Chern

2015-04-01

We report a fully automated DNA purification platform with a micropored membrane in the channel utilizing centrifugal microfluidics on a lab-on-a-disc (LOD). The microfluidic flow in the LOD, into which the reagents are injected for DNA purification, is controlled by a single motor and laser burst valve. The sample and reagents pass successively through the micropored membrane in the channel when each laser burst valve is opened. The Coriolis effect is used by rotating the LOD bi-directionally to increase the purity of the DNA, thereby preventing the mixing of the waste and elution solutions. The total process from the lysed sample injection into the LOD to obtaining the purified DNA was finished within 7 min with only one manual step. The experimental result for Salmonella shows that the proposed microfluidic platform is comparable to the existing devices in terms of the purity and yield of DNA.

Towards Biofilm Spectroscopy - A Novel Microfluidic Approach for Characterizing Biofilm Subpopulation by Microwave-Based Electrical Impedance Spectroscopy

NASA Astrophysics Data System (ADS)

Richter, Christiane; Schneider, Stefan; Rapp, Bastian E.; Schmidt, Sönke; Schüßler, Martin; Jakoby, Rolf; Bruchmann, Julia; Bischer, Moritz; Schwartz, Thomas

2018-03-01

In this work three disciplines - microfluidics, microbiology and microwave engineering - are utilized to develop a system for analyzing subpopulations of biofilms and their reaction to antibiotic treatment. We present handling strategies to destabilize a biofilm inside a microfluidic system down to aggregate sizes of<10 µm2 as well as microfluidic structures for the flow-through filtration of the resulting cell suspensions. For the analysis of the cell populations by microwave electrical impedance spectroscopy, two novel calibration schemes are demonstrated to cover both, reflection as well as transmission measurements of dielectric fluids. The broadband calibration strategies are solely based on liquid standards and allow a precise long-term monitoring with a resolution up to Δ ɛ = 6 Δ = 1.5 ‰ at H 5 GHz. Combining these three research topics therefore will open up new ways for analyzing biofilm effects.

Biomimetic engineering of a generic cell-on-membrane architecture by microfluidic engraving for on-chip bioassays.

PubMed

Lee, Sang-Wook; Noh, Ji-Yoon; Park, Seung Chul; Chung, Jin-Ho; Lee, Byoungho; Lee, Sin-Doo

2012-05-22

We develop a biomimetic cell-on-membrane architecture in close-volume format which allows the interfacial biocompatibility and the reagent delivery capability for on-chip bioassays. The key concept lies in the microfluidic engraving of lipid membranes together with biological cells on a supported substrate with topographic patterns. The simultaneous engraving process of a different class of fluids is promoted by the front propagation of an air-water interface inside a flow-cell. This highly parallel, microfluidic cell-on-membrane approach opens a door to the natural biocompatibility in mimicking cellular stimuli-response behavior essential for diverse on-chip bioassays that can be precisely controlled in the spatial and temporal manner.

Direct-referencing Two-dimensional-array Digital Microfluidics Using Multi-layer Printed Circuit Board

PubMed Central

Gong, Jian; Kim, Chang-Jin “CJ”

2008-01-01

Digital (i.e. droplet-based) microfluidics, by the electrowetting-on-dielectric (EWOD) mechanism, has shown great potential for a wide range of applications, such as lab-on-a-chip. While most reported EWOD chips use a series of electrode pads essentially in one-dimensional line pattern designed for specific tasks, the desired universal chips allowing user-reconfigurable paths would require the electrode pads in two-dimensional pattern. However, to electrically access the electrode pads independently, conductive lines need to be fabricated underneath the pads in multiple layers, raising a cost issue especially for disposable chip applications. In this article, we report the building of digital microfluidic plates based on a printed-circuit-board (PCB), in which multilayer electrical access lines were created inexpensively using mature PCB technology. However, due to its surface topography and roughness and resulting high resistance against droplet movement, as-fabricated PCB surfaces require unacceptably high (~500 V) voltages unless coated with or immersed in oil. Our goal is EWOD operations of aqueous droplets not only on oil-covered but also on dry surfaces. To meet varying levels of performances, three types of gradually complex post-PCB microfabrication processes are developed and evaluated. By introducing land-grid-array (LGA) sockets in the packaging, a scalable digital microfluidics system with reconfigurable and low-cost chip is also demonstrated. PMID:19234613

From Open Content to Open Course Models: Increasing Access and Enabling Global Participation in Higher Education

ERIC Educational Resources Information Center

Morgan, Tannis; Carey, Stephen

2009-01-01

Two of the major challenges to international students' right of access to higher education are geographical/economic isolation and academic literacy in English (Carey, 1999; Hamel, 2007). The authors propose that adopting open course models in traditional universities, through blended or online delivery, can offer benefits to the institutions and…

Characterization of a microfluidic microbial fuel cell as a power generator based on a nickel electrode.

PubMed

Mardanpour, Mohammad Mahdi; Yaghmaei, Soheila

2016-05-15

This study reports the fabrication of a microfluidic microbial fuel cell (MFC) using nickel as a novel alternative for conventional electrodes and a non-phatogenic strain of Escherichia coli as the biocatalyst. The feasibility of a microfluidic MFC as an efficient power generator for production of bioelectricity from glucose and urea as organic substrates in human blood and urine for implantable medical devices (IMDs) was investigated. A maximum open circuit potential of 459 mV was achieved for the batch-fed microfluidic MFC. During continuous mode operation, a maximum power density of 104 Wm(-3) was obtained with nutrient broth. For the glucose-fed microfluidic MFC, the maximum power density of 5.2 μW cm(-2) obtained in this study is significantly greater than the power densities reported previously for microsized MFCs and glucose fuel cells. The maximum power density of 14 Wm(-3) obtained using urea indicates the successful performance of a microfluidic MFC using human excreta. It features high power density, self-regeneration, waste management and a low production cost (<$1), which suggest it as a promising alternative to conventional power supplies for IMDs. The performance of the microfluidic MFC as a power supply was characterized based on polarization behavior and cell potential in different substrates, operational modes, and concentrations. Copyright © 2015 Elsevier B.V. All rights reserved.

SNARE-mediated Fusion of Single Proteoliposomes with Tethered Supported Bilayers in a Microfluidic Flow Cell Monitored by Polarized TIRF Microscopy

PubMed Central

Nikolaus, Joerg; Karatekin, Erdem

2016-01-01

In the ubiquitous process of membrane fusion the opening of a fusion pore establishes the first connection between two formerly separate compartments. During neurotransmitter or hormone release via exocytosis, the fusion pore can transiently open and close repeatedly, regulating cargo release kinetics. Pore dynamics also determine the mode of vesicle recycling; irreversible resealing results in transient, "kiss-and-run" fusion, whereas dilation leads to full fusion. To better understand what factors govern pore dynamics, we developed an assay to monitor membrane fusion using polarized total internal reflection fluorescence (TIRF) microscopy with single molecule sensitivity and ~15 msec time resolution in a biochemically well-defined in vitro system. Fusion of fluorescently labeled small unilamellar vesicles containing v-SNARE proteins (v-SUVs) with a planar bilayer bearing t-SNAREs, supported on a soft polymer cushion (t-SBL, t-supported bilayer), is monitored. The assay uses microfluidic flow channels that ensure minimal sample consumption while supplying a constant density of SUVs. Exploiting the rapid signal enhancement upon transfer of lipid labels from the SUV to the SBL during fusion, kinetics of lipid dye transfer is monitored. The sensitivity of TIRF microscopy allows tracking single fluorescent lipid labels, from which lipid diffusivity and SUV size can be deduced for every fusion event. Lipid dye release times can be much longer than expected for unimpeded passage through permanently open pores. Using a model that assumes retardation of lipid release is due to pore flickering, a pore "openness", the fraction of time the pore remains open during fusion, can be estimated. A soluble marker can be encapsulated in the SUVs for simultaneous monitoring of lipid and soluble cargo release. Such measurements indicate some pores may reseal after losing a fraction of the soluble cargo. PMID:27585113

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

Open microfluidic gel electrophoresis: Rapid and low cost separation and analysis of DNA at the nanoliter scale.

PubMed

Gutzweiler, Ludwig; Gleichmann, Tobias; Tanguy, Laurent; Koltay, Peter; Zengerle, Roland; Riegger, Lutz

2017-07-01

Gel electrophoresis is one of the most applied and standardized tools for separation and analysis of macromolecules and their fragments in academic research and in industry. In this work we present a novel approach for conducting on-demand electrophoretic separations of DNA molecules in open microfluidic (OM) systems on planar polymer substrates. The approach combines advantages of slab gel, capillary- and chip-based methods offering low consumable costs (<0.1$) circumventing cost-intensive microfluidic chip fabrication, short process times (5 min per analysis) and high sensitivity (4 ng/μL dsDNA) combined with reasonable resolution (17 bases). The open microfluidic separation system comprises two opposing reservoirs of 2-4 μL in volume, a semi-contact written gel line acting as separation channel interconnecting the reservoirs and sample injected into the line via non-contact droplet dispensing and thus enabling the precise control of the injection plug and sample concentration. Evaporation is prevented by covering aqueous structures with PCR-grade mineral oil while maintaining surface temperature at 15°C. The liquid gel line exhibits a semi-circular cross section of adaptable width (∼200-600 μm) and height (∼30-80 μm) as well as a typical length of 15-55 mm. Layout of such liquid structures is adaptable on-demand not requiring time consuming and repetitive fabrication steps. The approach was successfully demonstrated by the separation of a standard label-free DNA ladder (100-1000 bp) at 100 V/cm via in-line staining and laser induced fluorescent end-point detection using an automated prototype. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rapid fabrication of pressure-driven open-channel microfluidic devices in omniphobic R(F) paper.

PubMed

Glavan, Ana C; Martinez, Ramses V; Maxwell, E Jane; Subramaniam, Anand Bala; Nunes, Rui M D; Soh, Siowling; Whitesides, George M

2013-08-07

This paper describes the fabrication of pressure-driven, open-channel microfluidic systems with lateral dimensions of 45-300 microns carved in omniphobic paper using a craft-cutting tool. Vapor phase silanization with a fluorinated alkyltrichlorosilane renders paper omniphobic, but preserves its high gas permeability and mechanical properties. When sealed with tape, the carved channels form conduits capable of guiding liquid transport in the low-Reynolds number regime (i.e. laminar flow). These devices are compatible with complex fluids such as droplets of water in oil. The combination of omniphobic paper and a craft cutter enables the development of new types of valves and switches, such as "fold valves" and "porous switches," which provide new methods to control fluid flow.

System-level simulation of liquid filling in microfluidic chips.

PubMed

Song, Hongjun; Wang, Yi; Pant, Kapil

2011-06-01

Liquid filling in microfluidic channels is a complex process that depends on a variety of geometric, operating, and material parameters such as microchannel geometry, flow velocity∕pressure, liquid surface tension, and contact angle of channel surface. Accurate analysis of the filling process can provide key insights into the filling time, air bubble trapping, and dead zone formation, and help evaluate trade-offs among the various design parameters and lead to optimal chip design. However, efficient modeling of liquid filling in complex microfluidic networks continues to be a significant challenge. High-fidelity computational methods, such as the volume of fluid method, are prohibitively expensive from a computational standpoint. Analytical models, on the other hand, are primarily applicable to idealized geometries and, hence, are unable to accurately capture chip level behavior of complex microfluidic systems. This paper presents a parametrized dynamic model for the system-level analysis of liquid filling in three-dimensional (3D) microfluidic networks. In our approach, a complex microfluidic network is deconstructed into a set of commonly used components, such as reservoirs, microchannels, and junctions. The components are then assembled according to their spatial layout and operating rationale to achieve a rapid system-level model. A dynamic model based on the transient momentum equation is developed to track the liquid front in the microchannels. The principle of mass conservation at the junction is used to link the fluidic parameters in the microchannels emanating from the junction. Assembly of these component models yields a set of differential and algebraic equations, which upon integration provides temporal information of the liquid filling process, particularly liquid front propagation (i.e., the arrival time). The models are used to simulate the transient liquid filling process in a variety of microfluidic constructs and in a multiplexer, representing a complex microfluidic network. The accuracy (relative error less than 7%) and orders-of-magnitude speedup (30 000X-4 000 000X) of our system-level models are verified by comparison against 3D high-fidelity numerical studies. Our findings clearly establish the utility of our models and simulation methodology for fast, reliable analysis of liquid filling to guide the design optimization of complex microfluidic networks.

Microsphere integrated microfluidic disk: synergy of two techniques for rapid and ultrasensitive dengue detection

PubMed Central

Hosseini, Samira; Aeinehvand, Mohammad M.; Uddin, Shah M.; Benzina, Abderazak; Rothan, Hussin A.; Yusof, Rohana; Koole, Leo H.; Madou, Marc J.; Djordjevic, Ivan; Ibrahim, Fatimah

2015-01-01

The application of microfluidic devices in diagnostic systems is well-established in contemporary research. Large specific surface area of microspheres, on the other hand, has secured an important position for their use in bioanalytical assays. Herein, we report a combination of microspheres and microfluidic disk in a unique hybrid platform for highly sensitive and selective detection of dengue virus. Surface engineered polymethacrylate microspheres with carefully designed functional groups facilitate biorecognition in a multitude manner. In order to maximize the utility of the microspheres’ specific surface area in biomolecular interaction, the microfluidic disk was equipped with a micromixing system. The mixing mechanism (microballoon mixing) enhances the number of molecular encounters between spheres and target analyte by accessing the entire sample volume more effectively, which subsequently results in signal amplification. Significant reduction of incubation time along with considerable lower detection limits were the prime motivations for the integration of microspheres inside the microfluidic disk. Lengthy incubations of routine analytical assays were reduced from 2 hours to 5 minutes while developed system successfully detected a few units of dengue virus. Obtained results make this hybrid microsphere-microfluidic approach to dengue detection a promising avenue for early detection of this fatal illness. PMID:26548806

BMC Medicine editorial board members on open access publishing.

PubMed

Carmont, Michael R; Lawn, Stephen D; Stray-Pedersen, Babill; Shoenfeld, Yehuda; Meier, Pascal

2014-01-21

In recognition of Open Access week (21st-27th October 2013), we asked some BMC Medicine Editorial Board Members to share their views and experiences on open access publishing. In this short video, they highlight the benefits of visibility and dissemination of their research, and discuss the future directions for this model of publishing.

BMC medicine editorial board members on open access publishing

PubMed Central

2014-01-01

In recognition of Open Access week (21st-27th October 2013), we asked some BMC Medicine Editorial Board Members to share their views and experiences on open access publishing. In this short video, they highlight the benefits of visibility and dissemination of their research, and discuss the future directions for this model of publishing. PMID:24447778

Computational analysis of integrated biosensing and shear flow in a microfluidic vascular model

NASA Astrophysics Data System (ADS)

Wong, Jeremy F.; Young, Edmond W. K.; Simmons, Craig A.

2017-11-01

Fluid flow and flow-induced shear stress are critical components of the vascular microenvironment commonly studied using microfluidic cell culture models. Microfluidic vascular models mimicking the physiological microenvironment also offer great potential for incorporating on-chip biomolecular detection. In spite of this potential, however, there are few examples of such functionality. Detection of biomolecules released by cells under flow-induced shear stress is a significant challenge due to severe sample dilution caused by the fluid flow used to generate the shear stress, frequently to the extent where the analyte is no longer detectable. In this work, we developed a computational model of a vascular microfluidic cell culture model that integrates physiological shear flow and on-chip monitoring of cell-secreted factors. Applicable to multilayer device configurations, the computational model was applied to a bilayer configuration, which has been used in numerous cell culture applications including vascular models. Guidelines were established that allow cells to be subjected to a wide range of physiological shear stress while ensuring optimal rapid transport of analyte to the biosensor surface and minimized biosensor response times. These guidelines therefore enable the development of microfluidic vascular models that integrate cell-secreted factor detection while addressing flow constraints imposed by physiological shear stress. Ultimately, this work will result in the addition of valuable functionality to microfluidic cell culture models that further fulfill their potential as labs-on-chips.

Laser ablated micropillar energy directors for ultrasonic welding of microfluidic systems

NASA Astrophysics Data System (ADS)

Esben Poulsen, Carl; Kistrup, Kasper; Korsgaard Andersen, Nis; Taboryski, Rafael; Fougt Hansen, Mikkel; Wolff, Anders

2016-06-01

We present a new type of energy director (ED) for ultrasonic welding of microfluidic systems. These micropillar EDs are based on the replication of cone like protrusion structures introduced using a pico-second laser and may therefore be added to any mould surface accessible to a pico-second laser beam. The technology is demonstrated on an injection moulded microfluidic device featuring high-aspect ratio (h  ×  w  =  2000 μm  ×  550 μm) and free-standing channel walls, where bonding is achieved with no detectable channel deformation. The bonding strength is similar to conventional EDs and the fabricated system can withstand pressures of over 9.5 bar.

Microfluidic Experiments Studying Pore Scale Interactions of Microbes and Geochemistry

NASA Astrophysics Data System (ADS)

Chen, M.; Kocar, B. D.

2016-12-01

Understanding how physical phenomena, chemical reactions, and microbial behavior interact at the pore-scale is crucial to understanding larger scale trends in groundwater chemistry. Recent studies illustrate the utility of microfluidic devices for illuminating pore-scale physical-biogeochemical processes and their control(s) on the cycling of iron, uranium, and other important elements 1-3. These experimental systems are ideal for examining geochemical reactions mediated by microbes, which include processes governed by complex biological phenomenon (e.g. biofilm formation, etc.)4. We present results of microfluidic experiments using a model metal reducing bacteria and varying pore geometries, exploring the limitations of the microorganisms' ability to access tight pore spaces, and examining coupled biogeochemical-physical controls on the cycling of redox sensitive metals. Experimental results will provide an enhanced understanding of coupled physical-biogeochemical processes transpiring at the pore-scale, and will constrain and compliment continuum models used to predict and describe the subsurface cycling of redox-sensitive elements5. 1. Vrionis, H. A. et al. Microbiological and geochemical heterogeneity in an in situ uranium bioremediation field site. Appl. Environ. Microbiol. 71, 6308-6318 (2005). 2. Pearce, C. I. et al. Pore-scale characterization of biogeochemical controls on iron and uranium speciation under flow conditions. Environ. Sci. Technol. 46, 7992-8000 (2012). 3. Zhang, C., Liu, C. & Shi, Z. Micromodel investigation of transport effect on the kinetics of reductive dissolution of hematite. Environ. Sci. Technol. 47, 4131-4139 (2013). 4. Ginn, T. R. et al. Processes in microbial transport in the natural subsurface. Adv. Water Resour. 25, 1017-1042 (2002). 5. Scheibe, T. D. et al. Coupling a genome-scale metabolic model with a reactive transport model to describe in situ uranium bioremediation. Microb. Biotechnol. 2, 274-286 (2009).

Microfluidic Chips Controlled with Elastomeric Microvalve Arrays

PubMed Central

Li, Nianzhen; Sip, Chris; Folch, Albert

2007-01-01

Miniaturized microfluidic systems provide simple and effective solutions for low-cost point-of-care diagnostics and high-throughput biomedical assays. Robust flow control and precise fluidic volumes are two critical requirements for these applications. We have developed microfluidic chips featuring elastomeric polydimethylsiloxane (PDMS) microvalve arrays that: 1) need no extra energy source to close the fluidic path, hence the loaded device is highly portable; and 2) allow for microfabricating deep (up to 1 mm) channels with vertical sidewalls and resulting in very precise features. The PDMS microvalves-based devices consist of three layers: a fluidic layer containing fluidic paths and microchambers of various sizes, a control layer containing the microchannels necessary to actuate the fluidic path with microvalves, and a middle thin PDMS membrane that is bound to the control layer. Fluidic layer and control layers are made by replica molding of PDMS from SU-8 photoresist masters, and the thin PDMS membrane is made by spinning PDMS at specified heights. The control layer is bonded to the thin PDMS membrane after oxygen activation of both, and then assembled with the fluidic layer. The microvalves are closed at rest and can be opened by applying negative pressure (e.g., house vacuum). Microvalve closure and opening are automated via solenoid valves controlled by computer software. Here, we demonstrate two microvalve-based microfluidic chips for two different applications. The first chip allows for storing and mixing precise sub-nanoliter volumes of aqueous solutions at various mixing ratios. The second chip allows for computer-controlled perfusion of microfluidic cell cultures. The devices are easy to fabricate and simple to control. Due to the biocompatibility of PDMS, these microchips could have broad applications in miniaturized diagnostic assays as well as basic cell biology studies. PMID:18989408

Shrinking microbubbles with microfluidics: mathematical modelling to control microbubble sizes.

PubMed

Salari, A; Gnyawali, V; Griffiths, I M; Karshafian, R; Kolios, M C; Tsai, S S H

2017-11-29

Microbubbles have applications in industry and life-sciences. In medicine, small encapsulated bubbles (<10 μm) are desirable because of their utility in drug/oxygen delivery, sonoporation, and ultrasound diagnostics. While there are various techniques for generating microbubbles, microfluidic methods are distinguished due to their precise control and ease-of-fabrication. Nevertheless, sub-10 μm diameter bubble generation using microfluidics remains challenging, and typically requires expensive equipment and cumbersome setups. Recently, our group reported a microfluidic platform that shrinks microbubbles to sub-10 μm diameters. The microfluidic platform utilizes a simple microbubble-generating flow-focusing geometry, integrated with a vacuum shrinkage system, to achieve microbubble sizes that are desirable in medicine, and pave the way to eventual clinical uptake of microfluidically generated microbubbles. A theoretical framework is now needed to relate the size of the microbubbles produced and the system's input parameters. In this manuscript, we characterize microbubbles made with various lipid concentrations flowing in solutions that have different interfacial tensions, and monitor the changes in bubble size along the microfluidic channel under various vacuum pressures. We use the physics governing the shrinkage mechanism to develop a mathematical model that predicts the resulting bubble sizes and elucidates the dominant parameters controlling bubble sizes. The model shows a good agreement with the experimental data, predicting the resulting microbubble sizes under different experimental input conditions. We anticipate that the model will find utility in enabling users of the microfluidic platform to engineer bubbles of specific sizes.

Microfluidic Devices for Drug Delivery Systems and Drug Screening

PubMed Central

Kompella, Uday B.; Damiati, Safa A.

2018-01-01

Microfluidic devices present unique advantages for the development of efficient drug carrier particles, cell-free protein synthesis systems, and rapid techniques for direct drug screening. Compared to bulk methods, by efficiently controlling the geometries of the fabricated chip and the flow rates of multiphase fluids, microfluidic technology enables the generation of highly stable, uniform, monodispersed particles with higher encapsulation efficiency. Since the existing preclinical models are inefficient drug screens for predicting clinical outcomes, microfluidic platforms might offer a more rapid and cost-effective alternative. Compared to 2D cell culture systems and in vivo animal models, microfluidic 3D platforms mimic the in vivo cell systems in a simple, inexpensive manner, which allows high throughput and multiplexed drug screening at the cell, organ, and whole-body levels. In this review, the generation of appropriate drug or gene carriers including different particle types using different configurations of microfluidic devices is highlighted. Additionally, this paper discusses the emergence of fabricated microfluidic cell-free protein synthesis systems for potential use at point of care as well as cell-, organ-, and human-on-a-chip models as smart, sensitive, and reproducible platforms, allowing the investigation of the effects of drugs under conditions imitating the biological system. PMID:29462948

Biodegradability and platelets adhesion assessment of magnesium-based alloys using a microfluidic system

PubMed Central

Liu, Lumei; Koo, Youngmi; Collins, Boyce; Xu, Zhigang; Sankar, Jagannathan

2017-01-01

Magnesium (Mg)-based stents are extensively explored to alleviate atherosclerosis due to their biodegradability and relative hemocompatibility. To ensure the quality, safety and cost-efficacy of bioresorbable scaffolds and full utilization of the material tunability afforded by alloying, it is critical to access degradability and thrombosis potential of Mg-based alloys using improved in vitro models that mimic as closely as possible the in vivo microenvironment. In this study, we investigated biodegradation and initial thrombogenic behavior of Mg-based alloys at the interface between Mg alloys’ surface and simulated physiological environment using a microfluidic system. The degradation properties of Mg-based alloys WE43, AZ31, ZWEK-L, and ZWEK-C were evaluated in complete culture medium and their thrombosis potentials in platelet rich plasma, respectively. The results show that 1) physiological shear stress increased the corrosion rate and decreased platelets adhesion rate as compared to static immersion; 2) secondary phases and impurities in material composition induced galvanic corrosion, resulting in higher corrosion resistance and platelet adhesion rate; 3) Mg-based alloys with higher corrosion rate showed higher platelets adhesion rate. We conclude that a microfluidic-based in vitro system allows evaluation of biodegradation behaviors and platelets responses of Mg-based alloys under specific shear stress, and degradability is related to platelets adhesion. PMID:28797069

Geometric effects in microfluidics on heterogeneous cell stress using an Eulerian-Lagrangian approach.

PubMed

Warren, K M; Mpagazehe, J N; LeDuc, P R; Higgs, C F

2016-02-07

The response of individual cells at the micro-scale in cell mechanics is important in understanding how they are affected by changing environments. To control cell stresses, microfluidics can be implemented since there is tremendous control over the geometry of the devices. Designing microfluidic devices to induce and manipulate stress levels on biological cells can be aided by computational modeling approaches. Such approaches serve as an efficient precursor to fabricating various microfluidic geometries that induce predictable levels of stress on biological cells, based on their mechanical properties. Here, a three-dimensional, multiphase computational fluid dynamics (CFD) modeling approach was implemented for soft biological materials. The computational model incorporates the physics of the particle dynamics, fluid dynamics and solid mechanics, which allows us to study how stresses affect the cells. By using an Eulerian-Lagrangian approach to treat the fluid domain as a continuum in the microfluidics, we are conducting studies of the cells' movement and the stresses applied to the cell. As a result of our studies, we were able to determine that a channel with periodically alternating columns of obstacles was capable of stressing cells at the highest rate, and that microfluidic systems can be engineered to impose heterogenous cell stresses through geometric configuring. We found that when using controlled geometries of the microfluidics channels with staggered obstructions, we could increase the maximum cell stress by nearly 200 times over cells flowing through microfluidic channels with no obstructions. Incorporating computational modeling in the design of microfluidic configurations for controllable cell stressing could help in the design of microfludic devices for stressing cells such as cell homogenizers.

Microfluidics: an enabling screening technology for enhanced oil recovery (EOR).

PubMed

Lifton, Victor A

2016-05-21

Oil production is a critical industrial process that affects the entire world population and any improvements in its efficiency while reducing its environmental impact are of utmost societal importance. The paper reviews recent applications of microfluidics and microtechnology to study processes of oil extraction and recovery. It shows that microfluidic devices can be useful tools in investigation and visualization of such processes used in the oil & gas industry as fluid propagation, flooding, fracturing, emulsification and many others. Critical macro-scale processes that define oil extraction and recovery are controlled by the micro-scale processes based on wetting, adhesion, surface tension, colloids and other concepts of microfluidics. A growing number of research efforts demonstrates that microfluidics is becoming, albeit slowly, an accepted methodology in this area. We propose several areas of development where implementation of microfluidics may bring about deeper understanding and hence better control over the processes of oil recovery based on fluid propagation, droplet generation, wettability control. Studies of processes such as hydraulic fracturing, sand particle propagation in porous networks, high throughput screening of chemicals (for example, emulsifiers and surfactants) in microfluidic devices that simulate oil reservoirs are proposed to improve our understanding of these complicated physico-chemical systems. We also discuss why methods of additive manufacturing (3D printing) should be evaluated for quick prototyping and modification of the three-dimensional structures replicating natural oil-bearing rock formations for studies accessible to a wider audience of researchers.

Balancing Ideology and Feasibility: A Case Study on Adopting and Evaluating Open Access Publishing Models for a Society Journal within Philosophy

ERIC Educational Resources Information Center

Neuman, Yrsa; Laakso, Mikael

2017-01-01

Introduction: Open access, the notion that research output, such as journal articles, should be freely accessible to readers on the Web, is arguably in the best interest of science. In this article, we (1) describe in-depth how a society-owned philosophy journal, "Nordic Wittgenstein Review," evaluated various publishing models and made…

Droplet microfluidics--a tool for single-cell analysis.

PubMed

Joensson, Haakan N; Andersson Svahn, Helene

2012-12-03

Droplet microfluidics allows the isolation of single cells and reagents in monodisperse picoliter liquid capsules and manipulations at a throughput of thousands of droplets per second. These qualities allow many of the challenges in single-cell analysis to be overcome. Monodispersity enables quantitative control of solute concentrations, while encapsulation in droplets provides an isolated compartment for the single cell and its immediate environment. The high throughput allows the processing and analysis of the tens of thousands to millions of cells that must be analyzed to accurately describe a heterogeneous cell population so as to find rare cell types or access sufficient biological space to find hits in a directed evolution experiment. The low volumes of the droplets make very large screens economically viable. This Review gives an overview of the current state of single-cell analysis involving droplet microfluidics and offers examples where droplet microfluidics can further biological understanding. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microfluidic Serial Dilution Circuit

PubMed Central

Paegel, Brian M.; Grover, William H.; Skelley, Alison M.; Mathies, Richard A.; Joyce, Gerald F.

2008-01-01

In vitro evolution of RNA molecules requires a method for executing many consecutive serial dilutions. To solve this problem, a microfluidic circuit has been fabricated in a three-layer glass-PDMS-glass device. The 400-nL serial dilution circuit contains five integrated membrane valves: three two-way valves arranged in a loop to drive cyclic mixing of the diluent and carryover, and two bus valves to control fluidic access to the circuit through input and output channels. By varying the valve placement in the circuit, carryover fractions from 0.04 to 0.2 were obtained. Each dilution process, which is comprised of a diluent flush cycle followed by a mixing cycle, is carried out with no pipeting, and a sample volume of 400 nL is sufficient for conducting an arbitrary number of serial dilutions. Mixing is precisely controlled by changing the cyclic pumping rate, with a minimum mixing time of 22 s. This microfluidic circuit is generally applicable for integrating automated serial dilution and sample preparation in almost any microfluidic architecture. PMID:17073422

Label-free cell separation and sorting in microfluidic systems

PubMed Central

Gossett, Daniel R.; Weaver, Westbrook M.; Mach, Albert J.; Hur, Soojung Claire; Tse, Henry Tat Kwong; Lee, Wonhee; Amini, Hamed

2010-01-01

Cell separation and sorting are essential steps in cell biology research and in many diagnostic and therapeutic methods. Recently, there has been interest in methods which avoid the use of biochemical labels; numerous intrinsic biomarkers have been explored to identify cells including size, electrical polarizability, and hydrodynamic properties. This review highlights microfluidic techniques used for label-free discrimination and fractionation of cell populations. Microfluidic systems have been adopted to precisely handle single cells and interface with other tools for biochemical analysis. We analyzed many of these techniques, detailing their mode of separation, while concentrating on recent developments and evaluating their prospects for application. Furthermore, this was done from a perspective where inertial effects are considered important and general performance metrics were proposed which would ease comparison of reported technologies. Lastly, we assess the current state of these technologies and suggest directions which may make them more accessible. Figure A wide range of microfluidic technologies have been developed to separate and sort cells by taking advantage of differences in their intrinsic biophysical properties PMID:20419490

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.

Automated Lab-on-a-Chip Technology for Fish Embryo Toxicity Tests Performed under Continuous Microperfusion (μFET).

PubMed

Zhu, Feng; Wigh, Adriana; Friedrich, Timo; Devaux, Alain; Bony, Sylvie; Nugegoda, Dayanthi; Kaslin, Jan; Wlodkowic, Donald

2015-12-15

The fish embryo toxicity (FET) biotest has gained popularity as one of the alternative approaches to acute fish toxicity tests in chemical hazard and risk assessment. Despite the importance and common acceptance of FET, it is still performed in multiwell plates and requires laborious and time-consuming manual manipulation of specimens and solutions. This work describes the design and validation of a microfluidic Lab-on-a-Chip technology for automation of the zebrafish embryo toxicity test common in aquatic ecotoxicology. The innovative device supports rapid loading and immobilization of large numbers of zebrafish embryos suspended in a continuous microfluidic perfusion as a means of toxicant delivery. Furthermore, we also present development of a customized mechatronic automation interface that includes a high-resolution USB microscope, LED cold light illumination, and miniaturized 3D printed pumping manifolds that were integrated to enable time-resolved in situ analysis of developing fish embryos. To investigate the applicability of the microfluidic FET (μFET) in toxicity testing, copper sulfate, phenol, ethanol, caffeine, nicotine, and dimethyl sulfoxide were tested as model chemical stressors. Results obtained on a chip-based system were compared with static protocols performed in microtiter plates. This work provides evidence that FET analysis performed under microperfusion opens a brand new alternative for inexpensive automation in aquatic ecotoxicology.

High frequency acoustic on-chip integration for particle characterization and manipulation in microfluidics

NASA Astrophysics Data System (ADS)

Li, Sizhe; Carlier, Julien; Toubal, Malika; Liu, Huiqin; Campistron, Pierre; Callens, Dorothée; Nassar, Georges; Nongaillard, Bertrand; Guo, Shishang

2017-10-01

This letter presents a microfluidic device that integrates high frequency (650 MHz) bulk acoustic waves for the realization of particle handling on-chip. The core structure of the microfluidic chip is made up of a confocal lens, a vertical reflection wall, and a ZnO film transducer coupled with a silicon substrate for exciting acoustic beams. The excited acoustic waves propagate in bulk silicon and are then guided by a 45° silicon mirror into the suspensions in the microchannel; afterwards, the acoustic energy is focused on particles by the confocal lens and reflected by a reflection wall. Parts of the reflected acoustic energy backtrack into the transducer, and acoustic attenuation measurements are characterized for particle detection. Meanwhile, a strong acoustic streaming phenomenon can be seen around the reflection wall, which is used to implement particle manipulation. This platform opens a frontier for on-chip integration of high sensitivity acoustic characterization and localized acoustic manipulation in microfluidics.

Microfluidics for Positron Emission Tomography (PET) Imaging Probe Development

PubMed Central

Wang, Ming-Wei; Lin, Wei-Yu; Liu, Kan; Masterman-Smith, Michael; Shen, Clifton Kwang-Fu

2012-01-01

Due to increased needs for Positron Emission Tomography (PET) scanning, high demands for a wide variety of radiolabeled compounds will have to be met by exploiting novel radiochemistry and engineering technologies to improve the production and development of PET probes. The application of microfluidic reactors to perform radiosyntheses is currently attracting a great deal of interest because of their potential to deliver many advantages over conventional labeling systems. Microfluidic-based radiochemistry can lead to the use of smaller quantities of precursors, accelerated reaction rates and easier purification processes with greater yield and higher specific activity of desired probes. Several ‘proof-of-principle’ examples, along with basics of device architecture and operation, and potential limitations of each design are discussed here. Along with the concept of radioisotope distribution from centralized cyclotron facilities to individual imaging centers and laboratories (“decentralized model”), an easy-to-use, standalone, flexible, fully-automated radiochemical microfluidic platform can open up to simpler and more cost-effective procedures for molecular imaging using PET. PMID:20643021

Reconfigurable microfluidic hanging drop network for multi-tissue interaction and analysis.

PubMed

Frey, Olivier; Misun, Patrick M; Fluri, David A; Hengstler, Jan G; Hierlemann, Andreas

2014-06-30

Integration of multiple three-dimensional microtissues into microfluidic networks enables new insights in how different organs or tissues of an organism interact. Here, we present a platform that extends the hanging-drop technology, used for multi-cellular spheroid formation, to multifunctional complex microfluidic networks. Engineered as completely open, 'hanging' microfluidic system at the bottom of a substrate, the platform features high flexibility in microtissue arrangements and interconnections, while fabrication is simple and operation robust. Multiple spheroids of different cell types are formed in parallel on the same platform; the different tissues are then connected in physiological order for multi-tissue experiments through reconfiguration of the fluidic network. Liquid flow is precisely controlled through the hanging drops, which enable nutrient supply, substance dosage and inter-organ metabolic communication. The possibility to perform parallelized microtissue formation on the same chip that is subsequently used for complex multi-tissue experiments renders the developed platform a promising technology for 'body-on-a-chip'-related research.

Numerical simulation of isolation of cancer cells in a microfluidic chip

NASA Astrophysics Data System (ADS)

Djukic, T.; Topalovic, M.; Filipovic, N.

2015-08-01

Cancer is a disease that is characterized by the uncontrolled increase of numbers of cells. Circulating tumour cells (CTCs) are separated from the primary tumor, circulate in the bloodstream and form metastases. Circulating tumor cells can be identified in the blood of a patient by taking a blood sample. Microfluidic chips are a new technique that is used to isolate these cells from the blood sample. In this paper a numerical model is presented that is able to simulate the motion of individual cells through a microfluidic chip. The proposed numerical model gives very valuable insight into the processes happening within a microfluidic chip. The accuracy of the proposed model is compared with experimental results. The experimental setup that is described in literature is used to create identical geometrical domains and define simulation parameters. A good agreement of experimental and numerical results demonstrates that the proposed model can be successfully used to simulate complex behaviour of CTCs inside microfluidic chips.

High-throughput manufacturing of size-tuned liposomes by a new microfluidics method using enhanced statistical tools for characterization.

PubMed

Kastner, Elisabeth; Kaur, Randip; Lowry, Deborah; Moghaddam, Behfar; Wilkinson, Alexander; Perrie, Yvonne

2014-12-30

Microfluidics has recently emerged as a new method of manufacturing liposomes, which allows for reproducible mixing in miliseconds on the nanoliter scale. Here we investigate microfluidics-based manufacturing of liposomes. The aim of these studies was to assess the parameters in a microfluidic process by varying the total flow rate (TFR) and the flow rate ratio (FRR) of the solvent and aqueous phases. Design of experiment and multivariate data analysis were used for increased process understanding and development of predictive and correlative models. High FRR lead to the bottom-up synthesis of liposomes, with a strong correlation with vesicle size, demonstrating the ability to in-process control liposomes size; the resulting liposome size correlated with the FRR in the microfluidics process, with liposomes of 50 nm being reproducibly manufactured. Furthermore, we demonstrate the potential of a high throughput manufacturing of liposomes using microfluidics with a four-fold increase in the volumetric flow rate, maintaining liposome characteristics. The efficacy of these liposomes was demonstrated in transfection studies and was modelled using predictive modeling. Mathematical modelling identified FRR as the key variable in the microfluidic process, with the highest impact on liposome size, polydispersity and transfection efficiency. This study demonstrates microfluidics as a robust and high-throughput method for the scalable and highly reproducible manufacture of size-controlled liposomes. Furthermore, the application of statistically based process control increases understanding and allows for the generation of a design-space for controlled particle characteristics. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Imagining a Gold Open Access Future: Attitudes, Behaviors, and Funding Scenarios among Authors of Academic Scholarship

ERIC Educational Resources Information Center

Tenopir, Carol; Dalton, Elizabeth D.; Christian, Lisa; Jones, Misty K.; McCabe, Mark; Smith, MacKenzie; Fish, Allison

2017-01-01

The viability of gold open access publishing models into the future will depend, in part, on the attitudes of authors toward open access (OA). In a survey of academics at four major research universities in North America, we examine academic authors' opinions and behaviors toward gold OA. The study allows us to see what academics know and perceive…

Photopatterned materials in bioanalytical microfluidic technology

PubMed Central

Tentori, Augusto M.; Herr, Amy E.

2011-01-01

Microfluidic technologies are playing an increasingly important role in biological inquiry. Sophisticated approaches to the microanalysis of biological specimens rely, in part, on the fine fluid and material control offered by microtechnology, as well as a sufficient capacity for systems integration. A suite of techniques that utilize photopatterning of polymers on fluidic surfaces, within fluidic volumes, and as primary device structures underpins recent technological innovation in bioanalysis. Well-characterized photopatterning approaches enable previously fabricated or commercially fabricated devices to be customized by the user in a straight-forward manner, making the tools accessible to laboratories that do not focus on microfabrication technology innovation. In this review of recent advances, we summarize reported microfluidic devices with photopatterned structures and regions as platforms for a diverse set of biological measurements and assays. PMID:21857772

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

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.

3D-glass molds for facile production of complex droplet microfluidic chips.

PubMed

Tovar, Miguel; Weber, Thomas; Hengoju, Sundar; Lovera, Andrea; Munser, Anne-Sophie; Shvydkiv, Oksana; Roth, Martin

2018-03-01

In order to leverage the immense potential of droplet microfluidics, it is necessary to simplify the process of chip design and fabrication. While polydimethylsiloxane (PDMS) replica molding has greatly revolutionized the chip-production process, its dependence on 2D-limited photolithography has restricted the design possibilities, as well as further dissemination of microfluidics to non-specialized labs. To break free from these restrictions while keeping fabrication straighforward, we introduce an approach to produce complex multi-height (3D) droplet microfluidic glass molds and subsequent chip production by PDMS replica molding. The glass molds are fabricated with sub-micrometric resolution using femtosecond laser machining technology, which allows directly realizing designs with multiple levels or even continuously changing heights. The presented technique significantly expands the experimental capabilities of the droplet microfluidic chip. It allows direct fabrication of multilevel structures such as droplet traps for prolonged observation and optical fiber integration for fluorescence detection. Furthermore, the fabrication of novel structures based on sloped channels (ramps) enables improved droplet reinjection and picoinjection or even a multi-parallelized drop generator based on gradients of confinement. The fabrication of these and other 3D-features is currently only available at such resolution by the presented strategy. Together with the simplicity of PDMS replica molding, this provides an accessible solution for both specialized and non-specialized labs to customize microfluidic experimentation and expand their possibilities.

NASA Tech Briefs, May 2009

NASA Technical Reports Server (NTRS)

2009-01-01

Topics covered include: Valve-"Health"-Monitoring System; Microstrip Antenna for Remote Sensing of Soil Moisture and Sea Surface Salinity; Biomedical Wireless Ambulatory Crew Monitor; Wireless Avionics Packet to Support Fault Tolerance for Flight Applications; Aerobot Autonomy Architecture; Submillimeter Confocal Imaging Active Module; Traveling-Wave Maser for 32 GHz; System Synchronizes Recordings from Separated Video Cameras; Piecewise-Planar Parabolic Reflectarray Antenna; Reducing Interference in ATC Voice Communication; EOS MLS Level 1B Data Processing, Version 2.2; Auto-Generated Semantic Processing Services; Geospatial Authentication; Maneuver Automation Software; Event Driven Messaging with Role-Based Subscriptions; Estimating Relative Positions of Outer-Space Structures; Fabricating PFPE Membranes for Capillary Electrophoresis; Linear Actuator Has Long Stroke and High Resolution; Installing a Test Tap on a Metal Battery Case; Fabricating PFPE Membranes for Microfluidic Valves and Pumps; Room-Temperature-Cured Copolymers for Lithium Battery Gel Electrolytes; Catalysts for Efficient Production of Carbon Nanotubes; Amorphous Silk Fibroin Membranes for Separation of CO2; "Zero-Mass" Noninvasive Pressure Transducers; Radial-Electric-Field Piezoelectric Diaphragm Pumps; Ejector-Enhanced, Pulsed, Pressure-Gain Combustor; Suppressing Ghost Diffraction in E-Beam-Written Gratings; Target-Tracking Camera for a Metrology System; Polarimetric Imaging using Two Photoelastic Modulators; Miniature Wide-Angle Lens for Small-Pixel Electronic Camera; Modal Filters for Infrared Interferometry; Mo(3)Sb(7-x)Te(x) for Thermoelectric Power Generation; Two-Dimensional Quantum Model of a Nanotransistor; Scanning Miniature Microscopes without Lenses; Manipulating Neutral Atoms in Chip-Based Magnetic Traps; Expansion Compression Contacts for Thermoelectric Legs; Processing Electromyographic Signals to Recognize Words; Physical Principle for Generation of Randomness; DSN Beowulf Cluster-Based VLBI Correlator; Hybrid NN/SVM Computational System for Optimizing Designs; Criteria for Modeling in LES of Multicomponent Fuel Flow; Computerized Machine for Cutting Space Shuttle Thermal Tiles; Orbiting Depot and Reusable Lander for Lunar Transportation; FPGA-Based Networked Phasemeter for a Heterodyne Interferometer; Aquarius Digital Processing Unit; Three-Dimensional Optical Coherence Tomography; Benchtop Antigen Detection Technique using Nanofiltration and Fluorescent Dyes; Isolation of Precursor Cells from Waste Solid Fat Tissue; Identification of Bacteria and Determination of Biological Indicators; Further Development of Scaffolds for Regeneration of Nerves; Chemically Assisted Photocatalytic Oxidation System; Use of Atomic Oxygen for Increased Water Contact Angles of Various Polymers for Biomedical Applications; Crashworthy Seats Would Afford Superior Protection; Open-Access, Low-Magnetic-Field MRI System for Lung Research; Microfluidic Mixing Technology for a Universal Health Sensor; Microfluidic Extraction of Biomarkers using Water as Solvent; Microwell Arrays for Studying Many Individual Cells; Droplet-Based Production of Liposomes; and Identifying and Inactivating Bacterial Spores

Microfluidic in-channel multi-electrode platform for neurotransmitter sensing

NASA Astrophysics Data System (ADS)

Kara, A.; Mathault, J.; Reitz, A.; Boisvert, M.; Tessier, F.; Greener, J.; Miled, A.

2016-03-01

In this project we present a microfluidic platform with in-channel micro-electrodes for in situ screening of bio/chemical samples through a lab-on-chip system. We used a novel method to incorporate electrochemical sensors array (16x20) connected to a PCB, which opens the way for imaging applications. A 200 μm height microfluidic channel was bonded to electrochemical sensors. The micro-channel contains 3 inlets used to introduce phosphate buffer saline (PBS), ferrocynide and neurotransmitters. The flow rate was controlled through automated micro-pumps. A multiplexer was used to scan electrodes and perform individual cyclic voltammograms by a custom potentiostat. The behavior of the system was linear in terms of variation of current versus concentration. It was used to detect the neurotransmitters serotonin, dopamine and glutamate.

A PDMS membrane microvalve with one-dimensional line valve seat for robust microfluidics

NASA Astrophysics Data System (ADS)

Park, Chin-Sung; Hwang, Kyu-Youn; Jung, Wonjong; Namkoong, Kak; Chung, Wonseok; Kim, Joon-Ho; Huh, Nam

2014-02-01

We have developed a monolithic polydimethylsiloxane (PDMS) membrane microvalve with an isotropically etched valve seat for robust microfluidics. In order to avoid bonding or sticking of the PDMS membrane to the valve seat during the bonding process, the valve seat was wet-etched to be a one-dimensional line instead of a plane. The simple wet-etching technique allowed for the fabrication of an anti-bonding architecture in a scalable manner, and it intrinsically prevented contact between the PDMS membrane and valve seat when no external force was applied (i.e., normally open). This approach enables the permanent device assembly so that the microfluidic chip can be operable in a wide range of fluid pressures (e.g., over 200 kPa) without any leakage and sticking problems.

Microfluidic PMMA interfaces for rectangular glass capillaries

NASA Astrophysics Data System (ADS)

Evander, Mikael; Tenje, Maria

2014-02-01

We present the design and fabrication of a polymeric capillary fluidic interface fabricated by micro-milling. The design enables the use of glass capillaries with any kind of cross-section in complex microfluidic setups. We demonstrate two different designs of the interface; a double-inlet interface for hydrodynamic focusing and a capillary interface with integrated pneumatic valves. Both capillary interfaces are presented together with examples of practical applications. This communication shows the design optimization and presents details of the fabrication process. The capillary interface opens up for the use of complex microfluidic systems in single-use glass capillaries. They also enable simple fabrication of glass/polymer hybrid devices that can be beneficial in many research fields where a pure polymer chip negatively affects the device's performance, e.g. acoustofluidics.

Multi-step Variable Height Photolithography for Valved Multilayer Microfluidic Devices.

PubMed

Brower, Kara; White, Adam K; Fordyce, Polly M

2017-01-27

Microfluidic systems have enabled powerful new approaches to high-throughput biochemical and biological analysis. However, there remains a barrier to entry for non-specialists who would benefit greatly from the ability to develop their own microfluidic devices to address research questions. Particularly lacking has been the open dissemination of protocols related to photolithography, a key step in the development of a replica mold for the manufacture of polydimethylsiloxane (PDMS) devices. While the fabrication of single height silicon masters has been explored extensively in literature, fabrication steps for more complicated photolithography features necessary for many interesting device functionalities (such as feature rounding to make valve structures, multi-height single-mold patterning, or high aspect ratio definition) are often not explicitly outlined. Here, we provide a complete protocol for making multilayer microfluidic devices with valves and complex multi-height geometries, tunable for any application. These fabrication procedures are presented in the context of a microfluidic hydrogel bead synthesizer and demonstrate the production of droplets containing polyethylene glycol (PEG diacrylate) and a photoinitiator that can be polymerized into solid beads. This protocol and accompanying discussion provide a foundation of design principles and fabrication methods that enables development of a wide variety of microfluidic devices. The details included here should allow non-specialists to design and fabricate novel devices, thereby bringing a host of recently developed technologies to their most exciting applications in biological laboratories.

Nanocrystal synthesis in microfluidic reactors: where next?

PubMed

Phillips, Thomas W; Lignos, Ioannis G; Maceiczyk, Richard M; deMello, Andrew J; deMello, John C

2014-09-07

The past decade has seen a steady rise in the use of microfluidic reactors for nanocrystal synthesis, with numerous studies reporting improved reaction control relative to conventional batch chemistry. However, flow synthesis procedures continue to lag behind batch methods in terms of chemical sophistication and the range of accessible materials, with most reports having involved simple one- or two-step chemical procedures directly adapted from proven batch protocols. Here we examine the current status of microscale methods for nanocrystal synthesis, and consider what role microreactors might ultimately play in laboratory-scale research and industrial production.

Optofluidics for handling and analysis of single living cells

NASA Astrophysics Data System (ADS)

Perozziello, Gerardo; Candeloro, Patrizio; Coluccio, Maria Laura; Di Fabrizio, Enzo

2017-11-01

Optofluidics is a field with important applications in areas such as biotechnology, chemical synthesis and analytical chemistry. Optofluidic devices combine optical elements into microfluidic devices in ways that increase portability and sensitivity of analysis for diagnostic or screening purposes .In fact in these devices fluids give fine adaptability, mobility and accessibility to nanoscale photonic devices which otherwise could not be realized using conventional devices. This review describes several cases inwhich optical or microfluidic approaches are used to trap single cells in proximity of integrated optical sensor for being analysed.

Librarians and Libraries Supporting Open Access Publishing

ERIC Educational Resources Information Center

Richard, Jennifer; Koufogiannakis, Denise; Ryan, Pam

2009-01-01

As new models of scholarly communication emerge, librarians and libraries have responded by developing and supporting new methods of storing and providing access to information and by creating new publishing support services. This article will examine the roles of libraries and librarians in developing and supporting open access publishing…

Thermally-actuated, phase change flow control for microfluidic systems.

PubMed

Chen, Zongyuan; Wang, Jing; Qian, Shizhi; Bau, Haim H

2005-11-01

An easy to implement, thermally-actuated, noninvasive method for flow control in microfluidic devices is described. This technique takes advantage of the phase change of the working liquid itself-the freezing and melting of a portion of a liquid slug-to noninvasively close and open flow passages (referred to as a phase change valve). The valve was designed for use in a miniature diagnostic system for detecting pathogens in oral fluids at the point of care. The paper describes the modeling, construction, and characteristics of the valve. The experimental results favorably agree with theoretical predictions. In addition, the paper demonstrates the use of the phase change valves for flow control, sample metering and distribution into multiple analysis paths, sealing of a polymerase chain reaction (PCR) chamber, and sample introduction into and withdrawal from a closed loop. The phase change valve is electronically addressable, does not require any moving parts, introduces only minimal dead volume, is leakage and contamination free, and is biocompatible.

Through thick and thin: a microfluidic approach for continuous measurements of biofilm viscosity and the effect of ionic strength.

PubMed

Paquet-Mercier, F; Parvinzadeh Gashti, M; Bellavance, J; Taghavi, S M; Greener, J

2016-11-29

Continuous, non-intrusive measurements of time-varying viscosity of Pseudomonas sp. biofilms are made using a microfluidic method that combines video tracking with a semi-empirical viscous flow model. The approach uses measured velocity and height of tracked biofilm segments, which move under the constant laminar flow of a nutrient solution. Following a low viscosity growth stage, rapid thickening was observed. During this stage, viscosity increased by over an order of magnitude in less than ten hours. The technique was also demonstrated as a promising platform for parallel experiments by subjecting multiple biofilm-laden microchannels to nutrient solutions containing NaCl in the range of 0 to 34 mM. Preliminary data suggest a strong relationship between ionic strength and biofilm properties, such as average viscosity and rapid thickening onset time. The technique opens the way for a combinatorial approach to study the response of biofilm viscosity under well-controlled physical, chemical and biological growth conditions.

Modelling of capillary-driven flow for closed paper-based microfluidic channels

NASA Astrophysics Data System (ADS)

Songok, Joel; Toivakka, Martti

2017-06-01

Paper-based microfluidics is an emerging field focused on creating inexpensive devices, with simple fabrication methods for applications in various fields including healthcare, environmental monitoring and veterinary medicine. Understanding the flow of liquid is important in achieving consistent operation of the devices. This paper proposes capillary models to predict flow in paper-based microfluidic channels, which include a flow accelerating hydrophobic top cover. The models, which consider both non-absorbing and absorbing substrates, are in good agreement with the experimental results.

In vitro microfluidic models of tumor microenvironment to screen transport of drugs and nanoparticles.

PubMed

Ozcelikkale, Altug; Moon, Hye-Ran; Linnes, Michael; Han, Bumsoo

2017-09-01

Advances in nanotechnology have enabled numerous types of nanoparticles (NPs) to improve drug delivery to tumors. While many NP systems have been proposed, their clinical translation has been less than anticipated primarily due to failure of current preclinical evaluation techniques to adequately model the complex interactions between the NP and physiological barriers of tumor microenvironment. This review focuses on microfluidic tumor models for characterization of delivery efficacy and toxicity of cancer nanomedicine. Microfluidics offer significant advantages over traditional macroscale cell cultures by enabling recapitulation of tumor microenvironment through precise control of physiological cues such as hydrostatic pressure, shear stress, oxygen, and nutrient gradients. Microfluidic systems have recently started to be adapted for screening of drugs and NPs under physiologically relevant settings. So far the two primary application areas of microfluidics in this area have been high-throughput screening using traditional culture settings such as single cells or multicellular tumor spheroids, and mimicry of tumor microenvironment for study of cancer-related cell-cell and cell-matrix interactions. These microfluidic technologies are also useful in modeling specific steps in NP delivery to tumor and characterize NP transport properties and outcomes by systematic variation of physiological conditions. Ultimately, it will be possible to design drug-screening platforms uniquely tailored for individual patient physiology using microfluidics. These in vitro models can contribute to development of precision medicine by enabling rapid and patient-specific evaluation of cancer nanomedicine. WIREs Nanomed Nanobiotechnol 2017, 9:e1460. doi: 10.1002/wnan.1460 For further resources related to this article, please visit the WIREs website. © 2017 Wiley Periodicals, Inc.

Matlab-Excel Interface for OpenDSS

DOE Office of Scientific and Technical Information (OSTI.GOV)

The software allows users of the OpenDSS grid modeling software to access their load flow models using a GUI interface developed in MATLAB. The circuit definitions are entered into a Microsoft Excel spreadsheet which makes circuit creation and editing a much simpler process than the basic text-based editors used in the native OpenDSS interface. Plot tools have been developed which can be accessed through a MATLAB GUI once the desired parameters have been simulated.

[Does open access publishing increase the impact of scientific articles? An empirical study in the field of intensive care medicine].

PubMed

Riera, M; Aibar, E

2013-05-01

Some studies suggest that open access articles are more often cited than non-open access articles. However, the relationship between open access and citations count in a discipline such as intensive care medicine has not been studied to date. The present article analyzes the effect of open access publishing of scientific articles in intensive care medicine journals in terms of citations count. We evaluated a total of 161 articles (76% being non-open access articles) published in Intensive Care Medicine in the year 2008. Citation data were compared between the two groups up until April 30, 2011. Potentially confounding variables for citation counts were adjusted for in a linear multiple regression model. The median number (interquartile range) of citations of non-open access articles was 8 (4-12) versus 9 (6-18) in the case of open access articles (p=0.084). In the highest citation range (>8), the citation count was 13 (10-16) and 18 (13-21) (p=0.008), respectively. The mean follow-up was 37.5 ± 3 months in both groups. In the 30-35 months after publication, the average number (mean ± standard deviation) of citations per article per month of non-open access articles was 0.28 ± 0.6 versus 0.38 ± 0.7 in the case of open access articles (p=0.043). Independent factors for citation advantage were the Hirsch index of the first signing author (β=0.207; p=0.015) and open access status (β=3.618; p=0.006). Open access publishing and the Hirsch index of the first signing author increase the impact of scientific articles. The open access advantage is greater for the more highly cited articles, and appears in the 30-35 months after publication. Copyright © 2012 Elsevier España, S.L. and SEMICYUC. All rights reserved.

[The Open Access Initiative (OAI) in the scientific literature].

PubMed

Sánchez-Martín, Francisco M; Millán Rodríguez, Félix; Villavicencio Mavrich, Humberto

2009-01-01

According to the declaration of the Budapest Open Access Initiative (OAI) is defined as a editorial model in which access to scientific journal literature and his use are free. Free flow of information allowed by Internet has been the basis of this initiative. The Bethesda and the Berlin declarations, supported by some international agencies, proposes to require researchers to deposit copies of all articles published in a self-archive or an Open Access repository, and encourage researchers to publish their research papers in journals Open Access. This paper reviews the keys of the OAI, with their strengths and controversial aspects; and it discusses the position of databases, search engines and repositories of biomedical information, as well as the attitude of the scientists, publishers and journals. So far the journal Actas Urológicas Españolas (Act Urol Esp) offer their contents on Open Access as On Line in Spanish and English.

Supporting open access to clinical trial data for researchers: The Duke Clinical Research Institute-Bristol-Myers Squibb Supporting Open Access to Researchers Initiative.

PubMed

Pencina, Michael J; Louzao, Darcy M; McCourt, Brian J; Adams, Monique R; Tayyabkhan, Rehbar H; Ronco, Peter; Peterson, Eric D

2016-02-01

There are growing calls for sponsors to increase transparency by providing access to clinical trial data. In response, Bristol-Myers Squibb and the Duke Clinical Research Institute have collaborated on a new initiative, Supporting Open Access to Researchers. The aim is to facilitate open sharing of Bristol-Myers Squibb trial data with interested researchers. Key features of the Supporting Open Access to Researchers data sharing model include an independent review committee that ensures expert consideration of each proposal, stringent data deidentification/anonymization and protection of patient privacy, requirement of prespecified statistical analysis plans, and independent review of manuscripts before submission for publication. We believe that these approaches will promote open science by allowing investigators to verify trial results as well as to pursue interesting secondary uses of trial data without compromising scientific integrity. Copyright © 2015 Elsevier Inc. All rights reserved.

Pulse-density modulation control of chemical oscillation far from equilibrium in a droplet open-reactor system

PubMed Central

Sugiura, Haruka; Ito, Manami; Okuaki, Tomoya; Mori, Yoshihito; Kitahata, Hiroyuki; Takinoue, Masahiro

2016-01-01

The design, construction and control of artificial self-organized systems modelled on dynamical behaviours of living systems are important issues in biologically inspired engineering. Such systems are usually based on complex reaction dynamics far from equilibrium; therefore, the control of non-equilibrium conditions is required. Here we report a droplet open-reactor system, based on droplet fusion and fission, that achieves dynamical control over chemical fluxes into/out of the reactor for chemical reactions far from equilibrium. We mathematically reveal that the control mechanism is formulated as pulse-density modulation control of the fusion–fission timing. We produce the droplet open-reactor system using microfluidic technologies and then perform external control and autonomous feedback control over autocatalytic chemical oscillation reactions far from equilibrium. We believe that this system will be valuable for the dynamical control over self-organized phenomena far from equilibrium in chemical and biomedical studies. PMID:26786848

Pulse-density modulation control of chemical oscillation far from equilibrium in a droplet open-reactor system.

PubMed

Sugiura, Haruka; Ito, Manami; Okuaki, Tomoya; Mori, Yoshihito; Kitahata, Hiroyuki; Takinoue, Masahiro

2016-01-20

The design, construction and control of artificial self-organized systems modelled on dynamical behaviours of living systems are important issues in biologically inspired engineering. Such systems are usually based on complex reaction dynamics far from equilibrium; therefore, the control of non-equilibrium conditions is required. Here we report a droplet open-reactor system, based on droplet fusion and fission, that achieves dynamical control over chemical fluxes into/out of the reactor for chemical reactions far from equilibrium. We mathematically reveal that the control mechanism is formulated as pulse-density modulation control of the fusion-fission timing. We produce the droplet open-reactor system using microfluidic technologies and then perform external control and autonomous feedback control over autocatalytic chemical oscillation reactions far from equilibrium. We believe that this system will be valuable for the dynamical control over self-organized phenomena far from equilibrium in chemical and biomedical studies.

Microfluidics-assisted in vitro drug screening and carrier production

PubMed Central

Tsui, Jonathan H.; Lee, Woohyuk; Pun, Suzie H.; Kim, Jungkyu; Kim, Deok-Ho

2013-01-01

Microfluidic platforms provide several unique advantages for drug development. In the production of drug carriers, physical properties such as size and shape, and chemical properties such as drug composition and pharmacokinetic parameters, can be modified simply and effectively by tuning the flow rate and geometries. Large numbers of carriers can then be fabricated with minimal effort and with little to no batch-to-batch variation. Additionally, cell or tissue culture models in microfluidic systems can be used as in vitro drug screening tools. Compared to in vivo animal models, microfluidic drug screening platforms allow for high-throughput and reproducible screening at a significantly lower cost, and when combined with current advances in tissue engineering, are also capable of mimicking native tissues. In this review, various microfluidic platforms for drug and gene carrier fabrication are reviewed to provide guidelines for designing appropriate carriers. In vitro microfluidic drug screening platforms designed for high-throughput analysis and replication of in vivo conditions are also reviewed to highlight future directions for drug research and development. PMID:23856409

Due diligence in the open-access explosion era: choosing a reputable journal for publication.

PubMed

Masten, Yondell; Ashcraft, Alyce

2017-11-15

Faculty are required to publish. Naïve and "in-a-hurry-to-publish" authors seek to publish in journals where manuscripts are rapidly accepted. Others may innocently submit to one of an increasing number of questionable/predatory journals, where predatory is defined as practices of publishing journals for exploitation of author-pays, open-access publication model by charging authors publication fees for publisher profit without provision of expected services (expert peer review, editing, archiving, and indexing published manuscripts) and promising almost instant publication. Authors may intentionally submit manuscripts to predatory journals for rapid publication without concern for journal quality. A brief summary of the open access "movement," suggestions for selecting reputable open access journals, and suggestion for avoiding predatory publishers/journals are described. The purpose is to alert junior and seasoned faculty about predatory publishers included among available open access journal listings. Brief review of open access publication, predatory/questionable journal characteristics, suggestions for selecting reputable open access journals and avoiding predatory publishers/journals are described. Time is required for intentionally performing due diligence in open access journal selection, based on publisher/journal quality, prior to manuscript submission or authors must be able to successfully withdraw manuscripts when submission to a questionable or predatory journal is discovered. © FEMS 2017.

Due diligence in the open-access explosion era: choosing a reputable journal for publication

PubMed Central

Ashcraft, Alyce

2017-01-01

Abstract Faculty are required to publish. Naïve and “in-a-hurry-to-publish” authors seek to publish in journals where manuscripts are rapidly accepted. Others may innocently submit to one of an increasing number of questionable/predatory journals, where predatory is defined as practices of publishing journals for exploitation of author-pays, open-access publication model by charging authors publication fees for publisher profit without provision of expected services (expert peer review, editing, archiving, and indexing published manuscripts) and promising almost instant publication. Authors may intentionally submit manuscripts to predatory journals for rapid publication without concern for journal quality. A brief summary of the open access “movement,” suggestions for selecting reputable open access journals, and suggestion for avoiding predatory publishers/journals are described. The purpose is to alert junior and seasoned faculty about predatory publishers included among available open access journal listings. Brief review of open access publication, predatory/questionable journal characteristics, suggestions for selecting reputable open access journals and avoiding predatory publishers/journals are described. Time is required for intentionally performing due diligence in open access journal selection, based on publisher/journal quality, prior to manuscript submission or authors must be able to successfully withdraw manuscripts when submission to a questionable or predatory journal is discovered. PMID:29040536

Blood Perfusion in Microfluidic Models of Pulmonary Capillary Networks: Role of Geometry and Hematocrit

NASA Astrophysics Data System (ADS)

Stauber, Hagit; Waisman, Dan; Sznitman, Josue; Technion-IIT Team; Department of Neonatology Carmel Medical Center; Faculty of Medicine-Technion IIT Collaboration

2015-11-01

Microfluidic platforms are increasingly used to study blood microflows at true physiological scale due to their ability to overcome manufacturing obstacle of complex anatomical morphologies, such as the organ-specific architectures of the microcirculation. In the present work, we utilize microfluidic platforms to devise in vitro models of the underlying pulmonary capillary networks (PCN), where capillary lengths and diameters are similar to the size of RBCs (~ 5-10 μm). To better understand flow characteristics and dispersion of red blood cells (RBCs) in PCNs, we have designed microfluidic models of alveolar capillary beds inspired by the seminal ``sheet flow'' model of Fung and Sobin (1969). Our microfluidic PCNs feature confined arrays of staggered pillars with diameters of ~ 5,7 and 10 μm, mimicking the dense structure of pulmonary capillary meshes. The devices are perfused with suspensions of RBCs at varying hematocrit levels under different flow rates. Whole-field velocity patterns using micro-PIV and single-cell tracking using PTV are obtained with fluorescently-labelled RBCs and discussed. Our experiments deliver a real-scale quantitative description of RBC perfusion characteristics across the pulmonary capillary microcirculation.

Highly Stretchable and Transparent Microfluidic Strain Sensors for Monitoring Human Body Motions.

PubMed

Yoon, Sun Geun; Koo, Hyung-Jun; Chang, Suk Tai

2015-12-16

We report a new class of simple microfluidic strain sensors with high stretchability, transparency, sensitivity, and long-term stability with no considerable hysteresis and a fast response to various deformations by combining the merits of microfluidic techniques and ionic liquids. The high optical transparency of the strain sensors was achieved by introducing refractive-index matched ionic liquids into microfluidic networks or channels embedded in an elastomeric matrix. The microfluidic strain sensors offer the outstanding sensor performance under a variety of deformations induced by stretching, bending, pressing, and twisting of the microfluidic strain sensors. The principle of our microfluidic strain sensor is explained by a theoretical model based on the elastic channel deformation. In order to demonstrate its capability of practical usage, the simple-structured microfluidic strain sensors were performed onto a finger, wrist, and arm. The highly stretchable and transparent microfluidic strain sensors were successfully applied as potential platforms for distinctively monitoring a wide range of human body motions in real time. Our novel microfluidic strain sensors show great promise for making future stretchable electronic devices.

"Predatory" Online Journals Lure Scholars Who Are Eager to Publish

ERIC Educational Resources Information Center

Stratford, Michael

2012-01-01

OMICS Publishing Group is an open-access publisher operating under an author-pays model. Unlike traditional journal subscriptions in which readers or institutions pay to read content, OMICS relies on its contributors for financial support. Although the author-pays model is not a new phenomenon in the realm of open access, its recent popularity has…

Controlling the trajectories of bubble trains at a microfluidic junction

NASA Astrophysics Data System (ADS)

Parthiban, Pravien; Khan, Saif

2011-11-01

The increasing number of applications facilitated by digital microfluidic flows has resulted in a sustained interest in not only understanding the diverse, interesting and often complex dynamics associated with such flows in microchannel networks but also in developing facile strategies to control them. We find that there are readily accessible flow speeds wherein resistance to flow in microchannels decreases with an increase in the number of confined bubbles present, and exploit this intriguing phenomenon to sort all bubble of a train exclusively into one of the arms of a nominally symmetric microfluidic loop. We also demonstrate how the arm into which the train filters into can be chosen by applying a temporary external stimulus by means of an additional flow of the continuous liquid into one the arms of the loop. Furthermore, we show how by tuning the magnitude and period of this temporary stimulus we can switch controllably, the traffic of bubbles between both arms of the loop even when the loop is asymmetric. The results of this work should aid in developing viable methods to regulate traffic of digital flows in microfluidic networks.

Long-Term Growth of Moss in Microfluidic Devices Enables Subcellular Studies in Development.

PubMed

Bascom, Carlisle S; Wu, Shu-Zon; Nelson, Katherine; Oakey, John; Bezanilla, Magdalena

2016-09-01

Key developmental processes that occur on the subcellular and cellular level or occur in occluded tissues are difficult to access, let alone image and analyze. Recently, culturing living samples within polydimethylsiloxane (PDMS) microfluidic devices has facilitated the study of hard-to-reach developmental events. Here, we show that an early diverging land plant, Physcomitrella patens, can be continuously cultured within PDMS microfluidic chambers. Because the PDMS chambers are bonded to a coverslip, it is possible to image P. patens development at high resolution over long time periods. Using PDMS chambers, we report that wild-type protonemal tissue grows at the same rate as previously reported for growth on solid medium. Using long-term imaging, we highlight key developmental events, demonstrate compatibility with high-resolution confocal microscopy, and obtain growth rates for a slow-growing mutant. By coupling the powerful genetic tools available to P. patens with long-term growth and imaging provided by PDMS microfluidic chambers, we demonstrate the capability to study cellular and subcellular developmental events in plants directly and in real time. © 2016 American Society of Plant Biologists. All rights reserved.

In Vitro Microfluidic Models of Mucus-Like Obstructions in Small Airways

NASA Astrophysics Data System (ADS)

Mulligan, Molly K.; Grotberg, James B.; Sznitman, Josué

2012-11-01

Liquid plugs can form in the lungs as a result of a host of different diseases, including cystic fibrosis and chronic obstructive pulmonary disease. The existence of such fluid obstructions have been found as far down in the bronchiole tree as the sixteenth generation, where bronchiole openings have diameters on the order of a hundred to a few hundred microns. Understanding the propagation of liquid plugs within the bifurcating branches of bronchiole airways is important because their presence in the lungs, and their rupture and break-up, can cause injury to the epithelial cells lining the airway walls as a result of high wall shear stresses. In particular, liquid plug rupture and break-up frequently occurs at airway bifurcations. Until present, however, experimental studies of liquid plugs have generally been restricted to Newtonian fluids that do not reflect the actual pseudoplastic properties of lung mucus. The present work attempts to uncover the propagation, rupture and break-up of mucus-like liquid plugs in the lower generations of the airway tree using microfluidic models. Our approach allows the dynamics of mucus-like plug break-up to be studied in real-time, in a one-to-one in vitro model, as a function of mucus rheology and bronchial tree geometry.

Magnetically-actuated artificial cilia for microfluidic propulsion.

PubMed

Khaderi, S N; Craus, C B; Hussong, J; Schorr, N; Belardi, J; Westerweel, J; Prucker, O; Rühe, J; den Toonder, J M J; Onck, P R

2011-06-21

In this paper we quantitatively analyse the performance of magnetically-driven artificial cilia for lab-on-a-chip applications. The artificial cilia are fabricated using thin polymer films with embedded magnetic nano-particles and their deformation is studied under different external magnetic fields and flows. A coupled magneto-mechanical solid-fluid model that accurately captures the interaction between the magnetic field, cilia and fluid is used to simulate the cilia motion. The elastic and magnetic properties of the cilia are obtained by fitting the results of the computational model to the experimental data. The performance of the artificial cilia with a non-uniform cross-section is characterised using the numerical model for two channel configurations that are of practical importance: an open-loop and a closed-loop channel. We predict that the flow and pressure head generated by the artificial cilia can be as high as 18 microlitres per minute and 3 mm of water, respectively. We also study the effect of metachronal waves on the flow generated and show that the fluid propelled increases drastically compared to synchronously beating cilia, and is unidirectional. This increase is significant even when the phase difference between adjacent cilia is small. The obtained results provide guidelines for the optimal design of magnetically-driven artificial cilia for microfluidic propulsion.

Fabrication of PDMS-Based Microfluidic Devices: Application for Synthesis of Magnetic Nanoparticles

NASA Astrophysics Data System (ADS)

Thu, Vu Thi; Mai, An Ngoc; Le The Tam; Van Trung, Hoang; Thu, Phung Thi; Tien, Bui Quang; Thuat, Nguyen Tran; Lam, Tran Dai

2016-05-01

In this work, we have developed a convenient approach to synthesize magnetic nanoparticles with relatively high magnetization and controllable sizes. This was realized by combining the traditional co-precipitation method and microfluidic techniques inside microfluidic devices. The device was first designed, and then fabricated using simplified soft-lithography techniques. The device was utilized to synthesize magnetite nanoparticles. The synthesized nanomaterials were thoroughly characterized using field emission scanning electron microscopy and a vibrating sample magnetometer. The results demonstrated that the as-prepared device can be utilized as a simple and effective tool to synthesize magnetic nanoparticles with the sizes less than 10 nm and magnetization more than 50 emu/g. The development of these devices opens new strategies to synthesize nanomaterials with more precise dimensions at narrow size-distribution and with controllable behaviors.

Nanofluidic interfaces in microfluidic networks

DOE PAGES

Millet, Larry J.; Doktycz, Mitchel John; Retterer, Scott T.

2015-09-24

The integration of nano- and microfluidic technologies enables the construction of tunable interfaces to physical and biological systems across relevant length scales. The ability to perform chemical manipulations of miniscule sample volumes is greatly enhanced through these technologies and extends the ability to manipulate and sample the local fluidic environments at subcellular, cellular and community or tissue scales. Here we describe the development of a flexible surface micromachining process for the creation of nanofluidic channel arrays integrated within SU-8 microfluidic networks. The use of a semi-porous, silicon rich, silicon nitride structural layer allows rapid release of the sacrificial silicon dioxidemore » during the nanochannel fabrication. Nanochannel openings that form the interface to biological samples are customized using focused ion beam milling. The compatibility of these interfaces with on-chip microbial culture is demonstrated.« less

Interactive, open source, travel time scenario modelling: tools to facilitate participation in health service access analysis.

PubMed

Fisher, Rohan; Lassa, Jonatan

2017-04-18

Modelling travel time to services has become a common public health tool for planning service provision but the usefulness of these analyses is constrained by the availability of accurate input data and limitations inherent in the assumptions and parameterisation. This is particularly an issue in the developing world where access to basic data is limited and travel is often complex and multi-modal. Improving the accuracy and relevance in this context requires greater accessibility to, and flexibility in, travel time modelling tools to facilitate the incorporation of local knowledge and the rapid exploration of multiple travel scenarios. The aim of this work was to develop simple open source, adaptable, interactive travel time modelling tools to allow greater access to and participation in service access analysis. Described are three interconnected applications designed to reduce some of the barriers to the more wide-spread use of GIS analysis of service access and allow for complex spatial and temporal variations in service availability. These applications are an open source GIS tool-kit and two geo-simulation models. The development of these tools was guided by health service issues from a developing world context but they present a general approach to enabling greater access to and flexibility in health access modelling. The tools demonstrate a method that substantially simplifies the process for conducting travel time assessments and demonstrate a dynamic, interactive approach in an open source GIS format. In addition this paper provides examples from empirical experience where these tools have informed better policy and planning. Travel and health service access is complex and cannot be reduced to a few static modeled outputs. The approaches described in this paper use a unique set of tools to explore this complexity, promote discussion and build understanding with the goal of producing better planning outcomes. The accessible, flexible, interactive and responsive nature of the applications described has the potential to allow complex environmental social and political considerations to be incorporated and visualised. Through supporting evidence-based planning the innovative modelling practices described have the potential to help local health and emergency response planning in the developing world.

An integrated optics microfluidic device for detecting single DNA molecules.

PubMed

Krogmeier, Jeffrey R; Schaefer, Ian; Seward, George; Yantz, Gregory R; Larson, Jonathan W

2007-12-01

A fluorescence-based integrated optics microfluidic device is presented, capable of detecting single DNA molecules in a high throughput and reproducible manner. The device integrates microfluidics for DNA stretching with two optical elements for single molecule detection (SMD): a plano-aspheric refractive lens for fluorescence excitation (illuminator) and a solid parabolic reflective mirror for fluorescence collection (collector). Although miniaturized in size, both optical components were produced and assembled onto the microfluidic device by readily manufacturable fabrication techniques. The optical resolution of the device is determined by the small and relatively low numerical aperture (NA) illuminator lens (0.10 effective NA, 4.0 mm diameter) that delivers excitation light to a diffraction limited 2.0 microm diameter spot at full width half maximum within the microfluidic channel. The collector (0.82 annular NA, 15 mm diameter) reflects the fluorescence over a large collection angle, representing 71% of a hemisphere, toward a single photon counting module in an infinity-corrected scheme. As a proof-of-principle experiment for this simple integrated device, individual intercalated lambda-phage DNA molecules (48.5 kb) were stretched in a mixed elongational-shear microflow, detected, and sized with a fluorescence signal to noise ratio of 9.9 +/-1.0. We have demonstrated that SMD does not require traditional high numerical aperture objective lenses and sub-micron positioning systems conventionally used in many applications. Rather, standard manufacturing processes can be combined in a novel way that promises greater accessibility and affordability for microfluidic-based single molecule applications.

Probing eukaryotic cell mechanics via mesoscopic simulations

NASA Astrophysics Data System (ADS)

Pivkin, Igor V.; Lykov, Kirill; Nematbakhsh, Yasaman; Shang, Menglin; Lim, Chwee Teck

2017-11-01

We developed a new mesoscopic particle based eukaryotic cell model which takes into account cell membrane, cytoskeleton and nucleus. The breast epithelial cells were used in our studies. To estimate the viscoelastic properties of cells and to calibrate the computational model, we performed micropipette aspiration experiments. The model was then validated using data from microfluidic experiments. Using the validated model, we probed contributions of sub-cellular components to whole cell mechanics in micropipette aspiration and microfluidics experiments. We believe that the new model will allow to study in silico numerous problems in the context of cell biomechanics in flows in complex domains, such as capillary networks and microfluidic devices.

Surface-tension driven open microfluidic platform for hanging droplet culture

PubMed Central

de Groot, T. E.; Veserat, K. S.; Berthier, E.; Beebe, D. J.; Theberge, A. B.

2015-01-01

The hanging droplet technique for three-dimensional tissue culture has been used for decades in biology labs, with the core technology remaining relatively unchanged. Recently microscale approaches have expanded the capabilities of the hanging droplet method, making it more user-friendly. We present a spontaneously driven, open hanging droplet culture platform to address many limitations of current platforms. Our platform makes use of two interconnected hanging droplet wells, a larger well where cells are cultured and a smaller well for user interface via a pipette. The two-well system results in lower shear stress in the culture well during fluid exchange, enabling shear sensitive or non-adherent cells to be cultured in a droplet. The ability to perform fluid exchanges in-droplet enables long-term culture, treatment, and characterization without disruption of the culture. The open well format of the platform was utilized to perform time-dependent coculture, enabling culture configurations with bone tissue scaffolds and cells grown in suspension. The open nature of the system allowed the direct addition or removal of tissue over the course of an experiment, manipulations that would be impractical in other microfluidic or hanging droplet culture platforms. PMID:26660268

Using an Adapted Microfluidic Olfactory Chip for the Imaging of Neuronal Activity in Response to Pheromones in Male C. Elegans Head Neurons

PubMed Central

Reilly, Douglas K.; Lawler, Daniel E.; Albrecht, Dirk R.; Srinivasan, Jagan

2017-01-01

The use of calcium indicators has greatly enhanced our understanding of neural dynamics and regulation. The nematode Caenorhabditis elegans, with its completely mapped nervous system and transparent anatomy, presents an ideal model for understanding real-time neural dynamics using calcium indicators. In combination with microfluidic technologies and experimental designs, calcium-imaging studies using these indicators are performed in both free-moving and trapped animals. However, most previous studies utilizing trapping devices, such as the olfactory chip described in Chronis et al., have devices designed for use in the more common hermaphrodite, as the less common male is both morphologically and structurally dissimilar. An adapted olfactory chip was designed and fabricated for increased efficiency in male neuronal imaging with using young adult animals. A turn was incorporated into the worm loading port to rotate the animals and to allow for the separation of the individual neurons within a bilateral pair in 2D imaging. Worms are exposed to a controlled flow of odorant within the microfluidic device, as described in previous hermaphrodite studies. Calcium transients are then analyzed using the open-source software ImageJ. The procedure described herein should allow for an increased amount of male-based C. elegans calcium imaging studies, deepening our understanding of the mechanisms of sex-specific neuronal signaling. PMID:28930991

Achieving open access to conservation science.

PubMed

Fuller, Richard A; Lee, Jasmine R; Watson, James E M

2014-12-01

Conservation science is a crisis discipline in which the results of scientific enquiry must be made available quickly to those implementing management. We assessed the extent to which scientific research published since the year 2000 in 20 conservation science journals is publicly available. Of the 19,207 papers published, 1,667 (8.68%) are freely downloadable from an official repository. Moreover, only 938 papers (4.88%) meet the standard definition of open access in which material can be freely reused providing attribution to the authors is given. This compares poorly with a comparable set of 20 evolutionary biology journals, where 31.93% of papers are freely downloadable and 7.49% are open access. Seventeen of the 20 conservation journals offer an open access option, but fewer than 5% of the papers are available through open access. The cost of accessing the full body of conservation science runs into tens of thousands of dollars per year for institutional subscribers, and many conservation practitioners cannot access pay-per-view science through their workplace. However, important initiatives such as Research4Life are making science available to organizations in developing countries. We urge authors of conservation science to pay for open access on a per-article basis or to choose publication in open access journals, taking care to ensure the license allows reuse for any purpose providing attribution is given. Currently, it would cost $51 million to make all conservation science published since 2000 freely available by paying the open access fees currently levied to authors. Publishers of conservation journals might consider more cost effective models for open access and conservation-oriented organizations running journals could consider a broader range of options for open access to nonmembers such as sponsorship of open access via membership fees. © 2014 The Authors. Conservation Biology published by Wiley Periodicals, Inc., on behalf of the Society for Conservation Biology.

Graphene nano-ink biosensor arrays on a microfluidic paper for multiplexed detection of metabolites.

PubMed

Labroo, Pratima; Cui, Yue

2014-02-27

The development of a miniaturized and low-cost platform for the highly sensitive, selective and rapid detection of multiplexed metabolites is of great interest for healthcare, pharmaceuticals, food science, and environmental monitoring. Graphene is a delicate single-layer, two-dimensional network of carbon atoms with extraordinary electrical sensing capability. Microfluidic paper with printing technique is a low cost matrix. Here, we demonstrated the development of graphene-ink based biosensor arrays on a microfluidic paper for the multiplexed detection of different metabolites, such as glucose, lactate, xanthine and cholesterol. Our results show that the graphene biosensor arrays can detect multiple metabolites on a microfluidic paper sensitively, rapidly and simultaneously. The device exhibits a fast measuring time of less than 2 min, a low detection limit of 0.3 μM, and a dynamic detection range of 0.3-15 μM. The process is simple and inexpensive to operate and requires a low consumption of sample volume. We anticipate that these results could open exciting opportunities for a variety of applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Self-Powered Viscosity and Pressure Sensing in Microfluidic Systems Based on the Piezoelectric Energy Harvesting of Flowing Droplets.

PubMed

Wang, Zhao; Tan, Lun; Pan, Xumin; Liu, Gao; He, Yahua; Jin, Wenchao; Li, Meng; Hu, Yongming; Gu, Haoshuang

2017-08-30

The rapid development of microscaled piezoelectric energy harvesters has provided a simple and highly efficient way for building self-powered sensor systems through harvesting the mechanical energy from the ambient environment. In this work, a self-powered microfluidic sensor that can harvest the mechanical energy of the fluid and simultaneously monitor their characteristics was fabricated by integrating the flexible piezoelectric poly(vinylidene fluoride) (PVDF) nanofibers with the well-designed microfluidic chips. Those devices could generate open-circuit high output voltage up to 1.8 V when a droplet of water is flowing past the suspended PVDF nanofibers and result in their periodical deformations. The impulsive output voltage signal allowed them to be utilized for droplets or bubbles counting in the microfluidic systems. Furthermore, the devices also exhibited self-powered sensing behavior due to the decreased voltage amplitude with increasing input pressure and liquid viscosity. The drop of output voltage could be attributed to the variation of flow condition and velocity of the droplets, leading to the reduced deformation of the piezoelectric PVDF layer and the decrease of the generated piezoelectric potential.

Perspective use of direct human blood as an energy source in air-breathing hybrid microfluidic fuel cells

NASA Astrophysics Data System (ADS)

Dector, A.; Escalona-Villalpando, R. A.; Dector, D.; Vallejo-Becerra, V.; Chávez-Ramírez, A. U.; Arriaga, L. G.; Ledesma-García, J.

2015-08-01

This work presents a flexible and light air-breathing hybrid microfluidic fuel cell (HμFC) operated under biological conditions. A mixture of glucose oxidase, glutaraldehyde, multi-walled carbon nanotubes and vulcan carbon (GOx/VC-MWCNT-GA) was used as the bioanode. Meanwhile, integrating an air-exposed electrode (Pt/C) as the cathode enabled direct oxygen delivery from air. The microfluidic fuel cell performance was evaluated using glucose obtained from three different sources as the fuel: 5 mM glucose in phosphate buffer, human serum and human blood. For the last fuel, an open circuit voltage and maximum power density of 0.52 V and 0.20 mW cm-2 (at 0.38 V) were obtained respectively; meanwhile the maximum current density was 1.1 mA cm-2. Furthermore, the stability of the device was measured in terms of recovery after several polarization curves, showing excellent results. Although this air-breathing HμFC requires technological improvements before being tested in a biomedical device, it represents the best performance to date for a microfluidic fuel cell using human blood as glucose source.

3D printed Lego®-like modular microfluidic devices based on capillary driving.

PubMed

Nie, Jing; Gao, Qing; Qiu, Jing-Jiang; Sun, Miao; Liu, An; Shao, Lei; Fu, Jian-Zhong; Zhao, Peng; He, Yong

2018-03-12

The field of how to rapidly assemble microfluidics with modular components continuously attracts researchers' attention, however, extra efforts must be devoted to solving the problems of leaking and aligning between individual modules. This paper presents a novel type of modular microfluidic device, driven by capillary force. There is no necessity for a strict seal or special alignment, and its open structures make it easy to integrate various stents and reactants. The key rationale for this method is to print different functional modules with a low-cost three-dimensional (3D) printer, then fill the channels with capillary materials and assemble them with plugs like Lego ® bricks. This rapidly reconstructed modular microfluidic device consists of a variety of common functional modules and other personalized modules, each module having a unified standard interface for easy assembly. As it can be printed by a desktop 3D printer, the manufacturing process is simple and efficient, with controllable regulation of the flow channel scale. Through diverse combinations of different modules, a variety of different functions can be achieved, without duplicating the manufacturing process. A single module can also be taken out for testing and analysis. What's more, combined with basic circuit components, it can serve as a low-cost Lego ® -like modular microfluidic circuits. As a proof of concept, the modular microfluidic device has been successfully demonstrated and used for stent degradation and cell cultures, revealing the potential use of this method in both chemical and biological research.

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

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.

Clinician accessible tools for GUI computational models of transcranial electrical stimulation: BONSAI and SPHERES.

PubMed

Truong, Dennis Q; Hüber, Mathias; Xie, Xihe; Datta, Abhishek; Rahman, Asif; Parra, Lucas C; Dmochowski, Jacek P; Bikson, Marom

2014-01-01

Computational models of brain current flow during transcranial electrical stimulation (tES), including transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS), are increasingly used to understand and optimize clinical trials. We propose that broad dissemination requires a simple graphical user interface (GUI) software that allows users to explore and design montages in real-time, based on their own clinical/experimental experience and objectives. We introduce two complimentary open-source platforms for this purpose: BONSAI and SPHERES. BONSAI is a web (cloud) based application (available at neuralengr.com/bonsai) that can be accessed through any flash-supported browser interface. SPHERES (available at neuralengr.com/spheres) is a stand-alone GUI application that allow consideration of arbitrary montages on a concentric sphere model by leveraging an analytical solution. These open-source tES modeling platforms are designed go be upgraded and enhanced. Trade-offs between open-access approaches that balance ease of access, speed, and flexibility are discussed. Copyright © 2014 Elsevier Inc. All rights reserved.

Plumbing Fixture for a Microfluidic Cartridge

NASA Technical Reports Server (NTRS)

Francis, Kevin

2007-01-01

A fixture has been devised for making the plumbing connections between a microfluidic device in a replaceable cartridge and an external fluidic system. The fixture includes a 0.25-in. (6.35-mm) thick steel plate, to which the cartridge is fastened by two 10-32 thumb screws. The plate holds one plumbing fitting for the inlet and one for the outlet of the microfluidic device. Each fitting includes a fused-silica tube of 0.006-in. (approx.0.15-mm) inside diameter within a fluorinated ethylene-propylene (FEP) tube of 0.0155-in. (approx.0.39-mm) inside diameter and 0.062- in. (approx.1.57-mm) outside diameter. The FEP tube is press-fit through the steel plate so that its exposed end is flush with the surface of the plate, and the silica tube protrudes 0.03 in. (approx.0.76 mm) from the plate/FEP-tube-end surface. The cartridge includes a glass cover plate that contains 0.06-mm-wide access ports. When the cartridge is fastened to the steel plate, the silica tubes become inserted through the access ports and into the body of the cartridge, while the ends of the FEP tubes become butted against the glass cover plate. An extremely tight seal is thereby made.

Open Access Could Transform Drug Discovery: A Case Study of JQ1.

PubMed

Arshad, Zeeshaan; Smith, James; Roberts, Mackenna; Lee, Wen Hwa; Davies, Ben; Bure, Kim; Hollander, Georg A; Dopson, Sue; Bountra, Chas; Brindley, David

2016-01-01

The cost to develop a new drug from target discovery to market is a staggering $1.8 billion, largely due to the very high attrition rate of drug candidates and the lengthy transition times during development. Open access is an emerging model of open innovation that places no restriction on the use of information and has the potential to accelerate the development of new drugs. To date, no quantitative assessment has yet taken place to determine the effects and viability of open access on the process of drug translation. This need is addressed within this study. The literature and intellectual property landscapes of the drug candidate JQ1, which was made available on an open access basis when discovered, and conventionally developed equivalents that were not are compared using the Web of Science and Thomson Innovation software, respectively. Results demonstrate that openly sharing the JQ1 molecule led to a greater uptake by a wider and more multi-disciplinary research community. A comparative analysis of the patent landscapes for each candidate also found that the broader scientific diaspora of the publically released JQ1 data enhanced innovation, evidenced by a greater number of downstream patents filed in relation to JQ1. The authors' findings counter the notion that open access drug discovery would leak commercial intellectual property. On the contrary, JQ1 serves as a test case to evidence that open access drug discovery can be an economic model that potentially improves efficiency and cost of drug discovery and its subsequent commercialization.

Implications of Massive Open Online Courses for Higher Education: Mitigating or Reifying Educational Inequities?

ERIC Educational Resources Information Center

Literat, Ioana

2015-01-01

The proliferation of massive open online courses (MOOCs) has stirred a fervent debate about global access to higher education. While some commentators praise MOOCs for expanding educational opportunities in a more open and accessible fashion, others criticize this trend as a threat to current models of higher education and a low-quality substitute…

A distributed data component for the open modeling interface

USDA-ARS?s Scientific Manuscript database

As the volume of collected data continues to increase in the environmental sciences, so does the need for effective means for accessing those data. We have developed an Open Modeling Interface (OpenMI) data component that retrieves input data for model components from environmental information syste...

An Open Source Model for Open Access Journal Publication

PubMed Central

Blesius, Carl R.; Williams, Michael A.; Holzbach, Ana; Huntley, Arthur C.; Chueh, Henry

2005-01-01

We describe an electronic journal publication infrastructure that allows a flexible publication workflow, academic exchange around different forms of user submissions, and the exchange of articles between publishers and archives using a common XML based standard. This web-based application is implemented on a freely available open source software stack. This publication demonstrates the Dermatology Online Journal's use of the platform for non-biased independent open access publication. PMID:16779183

Open Energy Info (OpenEI) (Fact Sheet)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

2010-12-01

The Open Energy Information (OpenEI.org) initiative is a free, open-source, knowledge-sharing platform. OpenEI was created to provide access to data, models, tools, and information that accelerate the transition to clean energy systems through informed decisions.

A Microfluidics and Agent-Based Modeling Framework for Investigating Spatial Organization in Bacterial Colonies: The Case of Pseudomonas Aeruginosa and H1-Type VI Secretion Interactions.

PubMed

Wilmoth, Jared L; Doak, Peter W; Timm, Andrea; Halsted, Michelle; Anderson, John D; Ginovart, Marta; Prats, Clara; Portell, Xavier; Retterer, Scott T; Fuentes-Cabrera, Miguel

2018-01-01

The factors leading to changes in the organization of microbial assemblages at fine spatial scales are not well characterized or understood. However, they are expected to guide the succession of community development and function toward specific outcomes that could impact human health and the environment. In this study, we put forward a combined experimental and agent-based modeling framework and use it to interpret unique spatial organization patterns of H1-Type VI secretion system (T6SS) mutants of P . aeruginosa under spatial confinement. We find that key parameters, such as T6SS-mediated cell contact and lysis, spatial localization, relative species abundance, cell density and local concentrations of growth substrates and metabolites are influenced by spatial confinement. The model, written in the accessible programming language NetLogo, can be adapted to a variety of biological systems of interest and used to simulate experiments across a broad parameter space. It was implemented and run in a high-throughput mode by deploying it across multiple CPUs, with each simulation representing an individual well within a high-throughput microwell array experimental platform. The microfluidics and agent-based modeling framework we present in this paper provides an effective means by which to connect experimental studies in microbiology to model development. The work demonstrates progress in coupling experimental results to simulation while also highlighting potential sources of discrepancies between real-world experiments and idealized models.

A Microfluidics and Agent-Based Modeling Framework for Investigating Spatial Organization in Bacterial Colonies: The Case of Pseudomonas Aeruginosa and H1-Type VI Secretion Interactions

PubMed Central

Wilmoth, Jared L.; Doak, Peter W.; Timm, Andrea; Halsted, Michelle; Anderson, John D.; Ginovart, Marta; Prats, Clara; Portell, Xavier; Retterer, Scott T.; Fuentes-Cabrera, Miguel

2018-01-01

The factors leading to changes in the organization of microbial assemblages at fine spatial scales are not well characterized or understood. However, they are expected to guide the succession of community development and function toward specific outcomes that could impact human health and the environment. In this study, we put forward a combined experimental and agent-based modeling framework and use it to interpret unique spatial organization patterns of H1-Type VI secretion system (T6SS) mutants of P. aeruginosa under spatial confinement. We find that key parameters, such as T6SS-mediated cell contact and lysis, spatial localization, relative species abundance, cell density and local concentrations of growth substrates and metabolites are influenced by spatial confinement. The model, written in the accessible programming language NetLogo, can be adapted to a variety of biological systems of interest and used to simulate experiments across a broad parameter space. It was implemented and run in a high-throughput mode by deploying it across multiple CPUs, with each simulation representing an individual well within a high-throughput microwell array experimental platform. The microfluidics and agent-based modeling framework we present in this paper provides an effective means by which to connect experimental studies in microbiology to model development. The work demonstrates progress in coupling experimental results to simulation while also highlighting potential sources of discrepancies between real-world experiments and idealized models. PMID:29467721

Shrink-film microfluidic education modules: Complete devices within minutes

PubMed Central

Nguyen, Diep; McLane, Jolie; Lew, Valerie; Pegan, Jonathan; Khine, Michelle

2011-01-01

As advances in microfluidics continue to make contributions to diagnostics and life sciences, broader awareness of this expanding field becomes necessary. By leveraging low-cost microfabrication techniques that require no capital equipment or infrastructure, simple, accessible, and effective educational modules can be made available for a broad range of educational needs from middle school demonstrations to college laboratory classes. These modules demonstrate key microfluidic concepts such as diffusion and separation as well as “laboratory on-chip” applications including chemical reactions and biological assays. These modules are intended to provide an interdisciplinary hands-on experience, including chip design, fabrication of functional devices, and experiments at the microscale. Consequently, students will be able to conceptualize physics at small scales, gain experience in computer-aided design and microfabrication, and perform experiments—all in the context of addressing real-world challenges by making their own lab-on-chip devices. PMID:21799715

Shrink-film microfluidic education modules: Complete devices within minutes.

PubMed

Nguyen, Diep; McLane, Jolie; Lew, Valerie; Pegan, Jonathan; Khine, Michelle

2011-06-01

As advances in microfluidics continue to make contributions to diagnostics and life sciences, broader awareness of this expanding field becomes necessary. By leveraging low-cost microfabrication techniques that require no capital equipment or infrastructure, simple, accessible, and effective educational modules can be made available for a broad range of educational needs from middle school demonstrations to college laboratory classes. These modules demonstrate key microfluidic concepts such as diffusion and separation as well as "laboratory on-chip" applications including chemical reactions and biological assays. These modules are intended to provide an interdisciplinary hands-on experience, including chip design, fabrication of functional devices, and experiments at the microscale. Consequently, students will be able to conceptualize physics at small scales, gain experience in computer-aided design and microfabrication, and perform experiments-all in the context of addressing real-world challenges by making their own lab-on-chip devices.

In-line microfluidic refractometer based on C-shaped fiber assisted photonic crystal fiber Sagnac interferometer.

PubMed

Wu, Chuang; Tse, Ming-Leung Vincent; Liu, Zhengyong; Guan, Bai-Ou; Lu, Chao; Tam, Hwa-Yaw

2013-09-01

We propose and demonstrate a highly sensitive in-line photonic crystal fiber (PCF) microfluidic refractometer. Ultrathin C-shaped fibers are spliced in-between the PCF and standard single-mode fibers. The C-shaped fibers provide openings for liquid to flow in and out of the PCF. Based on a Sagnac interferometer, the refractive index (RI) response of the device is investigated theoretically and experimentally. A high sensitivity of 6621 nm/RIU for liquid RI from 1.330 to 1.333 is achieved in the experiment, which agrees well with the theoretical analysis.

Entropy-based separation of yeast cells using a microfluidic system of conjoined spheres

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Kai-Jian; Qin, S.-J., E-mail: shuijie.qin@gmail.com; Bai, Zhong-Chen

2013-11-21

A physical model is derived to create a biological cell separator that is based on controlling the entropy in a microfluidic system having conjoined spherical structures. A one-dimensional simplified model of this three-dimensional problem in terms of the corresponding effects of entropy on the Brownian motion of particles is presented. This dynamic mechanism is based on the Langevin equation from statistical thermodynamics and takes advantage of the characteristics of the Fokker-Planck equation. This mechanism can be applied to manipulate biological particles inside a microfluidic system with identical, conjoined, spherical compartments. This theoretical analysis is verified by performing a rapid andmore » a simple technique for separating yeast cells in these conjoined, spherical microfluidic structures. The experimental results basically match with our theoretical model and we further analyze the parameters which can be used to control this separation mechanism. Both numerical simulations and experimental results show that the motion of the particles depends on the geometrical boundary conditions of the microfluidic system and the initial concentration of the diffusing material. This theoretical model can be implemented in future biophysics devices for the optimized design of passive cell sorters.« less

Optimized open-flow mixing: insights from microbubble streaming

NASA Astrophysics Data System (ADS)

Rallabandi, Bhargav; Wang, Cheng; Guo, Lin; Hilgenfeldt, Sascha

2015-11-01

Microbubble streaming has been developed into a robust and powerful flow actuation technique in microfluidics. Here, we study it as a paradigmatic system for microfluidic mixing under a continuous throughput of fluid (open-flow mixing), providing a systematic optimization of the device parameters in this practically important situation. Focusing on two-dimensional advective stirring (neglecting diffusion), we show through numerical simulation and analytical theory that mixing in steady streaming vortices becomes ineffective beyond a characteristic time scale, necessitating the introduction of unsteadiness. By duty cycling the streaming, such unsteadiness is introduced in a controlled fashion, leading to exponential refinement of the advection structures. The rate of refinement is then optimized for particular parameters of the time modulation, i.e. a particular combination of times for which the streaming is turned ``on'' and ``off''. The optimized protocol can be understood theoretically using the properties of the streaming vortices and the throughput Poiseuille flow. We can thus infer simple design principles for practical open flow micromixing applications, consistent with experiments. Current Address: Mechanical and Aerospace Engineering, Princeton University.

Accurately tracking single-cell movement trajectories in microfluidic cell sorting devices.

PubMed

Jeong, Jenny; Frohberg, Nicholas J; Zhou, Enlu; Sulchek, Todd; Qiu, Peng

2018-01-01

Microfluidics are routinely used to study cellular properties, including the efficient quantification of single-cell biomechanics and label-free cell sorting based on the biomechanical properties, such as elasticity, viscosity, stiffness, and adhesion. Both quantification and sorting applications require optimal design of the microfluidic devices and mathematical modeling of the interactions between cells, fluid, and the channel of the device. As a first step toward building such a mathematical model, we collected video recordings of cells moving through a ridged microfluidic channel designed to compress and redirect cells according to cell biomechanics. We developed an efficient algorithm that automatically and accurately tracked the cell trajectories in the recordings. We tested the algorithm on recordings of cells with different stiffness, and showed the correlation between cell stiffness and the tracked trajectories. Moreover, the tracking algorithm successfully picked up subtle differences of cell motion when passing through consecutive ridges. The algorithm for accurately tracking cell trajectories paves the way for future efforts of modeling the flow, forces, and dynamics of cell properties in microfluidics applications.

Wireless Sensor Network Radio Power Management and Simulation Models

DTIC Science & Technology

2010-01-01

The Open Electrical & Electronic Engineering Journal, 2010, 4, 21-31 21 1874-1290/10 2010 Bentham Open Open Access Wireless Sensor Network Radio...Air Force Institute of Technology, Wright-Patterson AFB, OH, USA Abstract: Wireless sensor networks (WSNs) create a new frontier in collecting and...consumption. Keywords: Wireless sensor network , power management, energy-efficiency, medium access control (MAC), simulation pa- rameters. 1

Photoresponsive Passive Micromixers Based on Spiropyran Size-Tunable Hydrogels.

PubMed

Ter Schiphorst, Jeroen; Melpignano, Giuseppe G; Amirabadi, Hossein Eslami; Houben, Menno H J M; Bakker, Sterre; den Toonder, Jaap M J; Schenning, Albertus P H J

2018-01-01

Microfluidic devices allow the manipulation of fluids down to the micrometer scale and are receiving a lot of attention for applications where low volumes and high throughputs are required. In these micro channels, laminar flow usually dominates, which requires long residence times of the fluids, limiting the flow speed and throughput. Here a switchable passive mixer has been developed to control mixing and to easily clean microchannels. The mixer is based on a photoresponsive spiropyran based hydrogel of which the dimensions can be tuned by changing the intensity of the light. The size-tunable gels have been used to fabricate a passive slanted groove mixer that can be switched off by light allowing to change mixing of microfluidics to non-mixed flows. These findings open new possibilities for multi-purpose microfluidic devices where mixers and valves can be tuned by light. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

PR-PR: Cross-Platform Laboratory Automation System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Linshiz, G; Stawski, N; Goyal, G

To enable protocol standardization, sharing, and efficient implementation across laboratory automation platforms, we have further developed the PR-PR open-source high-level biology-friendly robot programming language as a cross-platform laboratory automation system. Beyond liquid-handling robotics, PR-PR now supports microfluidic and microscopy platforms, as well as protocol translation into human languages, such as English. While the same set of basic PR-PR commands and features are available for each supported platform, the underlying optimization and translation modules vary from platform to platform. Here, we describe these further developments to PR-PR, and demonstrate the experimental implementation and validation of PR-PR protocols for combinatorial modified Goldenmore » Gate DNA assembly across liquid-handling robotic, microfluidic, and manual platforms. To further test PR-PR cross-platform performance, we then implement and assess PR-PR protocols for Kunkel DNA mutagenesis and hierarchical Gibson DNA assembly for microfluidic and manual platforms.« less

Constant flow-driven microfluidic oscillator for different duty cycles

PubMed Central

Kim, Sung-Jin; Yokokawa, Ryuji; Lesher-Perez, Sasha Cai; Takayama, Shuichi

2012-01-01

This paper presents microfluidic devices that autonomously convert two constant flow inputs into an alternating oscillatory flow output. We accomplish this hardware embedded self-control programming using normally closed membrane valves that have an inlet, an outlet, and a membrane-pressurization chamber connected to a third terminal. Adjustment of threshold opening pressures in these 3-terminal flow switching valves enabled adjustment of oscillation periods to between 57–360 s with duty cycles of 0.2–0.5. These values are in relatively good agreement with theoretical values, providing the way for rational design of an even wider range of different waveform oscillations. We also demonstrate the ability to use these oscillators to perform temporally patterned delivery of chemicals to living cells. The device only needs a syringe pump, thus removing the use of complex, expensive external actuators. These tunable waveform microfluidic oscillators are envisioned to facilitate cell-based studies that require temporal stimulation. PMID:22206453

Multiplex Particle Focusing via Hydrodynamic Force in Viscoelastic Fluids

NASA Astrophysics Data System (ADS)

Lee, Doo Jin; Brenner, Howard; Youn, Jae Ryoun; Song, Young Seok

2013-11-01

We introduce a multiplex particle focusing phenomenon that arises from the hydrodynamic interaction between the viscoelastic force and the Dean drag force in a microfluidic device. In a confined microchannel, the first normal stress difference of viscoelastic fluids results in a lateral migration of suspended particles. Such a viscoelastic force was harnessed to focus different sized particles in the middle of a microchannel, and spiral channel geometry was also considered in order to take advantage of the counteracting force, Dean drag force that induces particle migration in the outward direction. For theoretical understanding, we performed a numerical analysis of viscoelastic fluids in the spiral microfluidic channel. From these results, a concept of the `Dean-coupled Elasto-inertial Focusing band (DEF)' was proposed. This study provides in-depth physical insight into the multiplex focusing of particles that can open a new venue for microfluidic particle dynamics for a concrete high throughput platform at microscale.

PR-PR: cross-platform laboratory automation system.

PubMed

Linshiz, Gregory; Stawski, Nina; Goyal, Garima; Bi, Changhao; Poust, Sean; Sharma, Monica; Mutalik, Vivek; Keasling, Jay D; Hillson, Nathan J

2014-08-15

To enable protocol standardization, sharing, and efficient implementation across laboratory automation platforms, we have further developed the PR-PR open-source high-level biology-friendly robot programming language as a cross-platform laboratory automation system. Beyond liquid-handling robotics, PR-PR now supports microfluidic and microscopy platforms, as well as protocol translation into human languages, such as English. While the same set of basic PR-PR commands and features are available for each supported platform, the underlying optimization and translation modules vary from platform to platform. Here, we describe these further developments to PR-PR, and demonstrate the experimental implementation and validation of PR-PR protocols for combinatorial modified Golden Gate DNA assembly across liquid-handling robotic, microfluidic, and manual platforms. To further test PR-PR cross-platform performance, we then implement and assess PR-PR protocols for Kunkel DNA mutagenesis and hierarchical Gibson DNA assembly for microfluidic and manual platforms.

Crystallography Open Database – an open-access collection of crystal structures

PubMed Central

Gražulis, Saulius; Chateigner, Daniel; Downs, Robert T.; Yokochi, A. F. T.; Quirós, Miguel; Lutterotti, Luca; Manakova, Elena; Butkus, Justas; Moeck, Peter; Le Bail, Armel

2009-01-01

The Crystallography Open Database (COD), which is a project that aims to gather all available inorganic, metal–organic and small organic molecule structural data in one database, is described. The database adopts an open-access model. The COD currently contains ∼80 000 entries in crystallographic information file format, with nearly full coverage of the International Union of Crystallography publications, and is growing in size and quality. PMID:22477773

Experimental verification of the flow characteristics of an active controlled microfluidic valve with annular boundary

NASA Astrophysics Data System (ADS)

Pan, Chun-Peng; Wang, Dai-Hua

2014-03-01

The principle and structural configuration of an active controlled microfluidic valve with annular boundary is presented in this paper. The active controlled flowrate model of the active controlled microfluidic valve with annular boundary is established. The prototypes of the active controlled microfluidic valves with annular boundaries with three different combinations of the inner and outer radii are fabricated and tested on the established experimental setup. The experimental results show that: (1) The active controlled microfluidic valve with annular boundary possesses the on/off switching and the continuous control capability of the fluid with simple structure and easy fabrication processing; (2) When the inner and outer diameters of the annular boundary are 1.5 mm and 3.5 mm, respectively, the maximum flowrate of the valve is 0.14 ml/s when the differential pressure of the inlet and outlet of the valve is 1000 Pa and the voltage applied to circular piezoelectric unimorph actuator is 100 V; (3) The established active controlled flowrate model can accurately predict the controlled flowrate of the active controlled microfluidic valves with the maximum relative error of 6.7%. The results presented in this paper lay the foundation for designing and developing the active controlled microfluidic valves with annular boundary driven by circular piezoelectric unimorph actuators.

Microfluidic Devices in Advanced Caenorhabditis elegans Research.

PubMed

Muthaiyan Shanmugam, Muniesh; Subhra Santra, Tuhin

2016-08-02

The study of model organisms is very important in view of their potential for application to human therapeutic uses. One such model organism is the nematode worm, Caenorhabditis elegans. As a nematode, C. elegans have ~65% similarity with human disease genes and, therefore, studies on C. elegans can be translated to human, as well as, C. elegans can be used in the study of different types of parasitic worms that infect other living organisms. In the past decade, many efforts have been undertaken to establish interdisciplinary research collaborations between biologists, physicists and engineers in order to develop microfluidic devices to study the biology of C. elegans. Microfluidic devices with the power to manipulate and detect bio-samples, regents or biomolecules in micro-scale environments can well fulfill the requirement to handle worms under proper laboratory conditions, thereby significantly increasing research productivity and knowledge. The recent development of different kinds of microfluidic devices with ultra-high throughput platforms has enabled researchers to carry out worm population studies. Microfluidic devices primarily comprises of chambers, channels and valves, wherein worms can be cultured, immobilized, imaged, etc. Microfluidic devices have been adapted to study various worm behaviors, including that deepen our understanding of neuromuscular connectivity and functions. This review will provide a clear account of the vital involvement of microfluidic devices in worm biology.

Design of a rapid magnetic microfluidic mixer

NASA Astrophysics Data System (ADS)

Ballard, Matthew; Owen, Drew; Mills, Zachary Grant; Hanasoge, Srinivas; Hesketh, Peter; Alexeev, Alexander

2015-11-01

Using three-dimensional simulations and experiments, we demonstrate rapid mixing of fluid streams in a microchannel using orbiting magnetic microbeads. We use a lattice Boltzmann model coupled to a Brownian dynamics model to perform numerical simulations that study in depth the effect of system parameters such as channel configuration and fluid and bead velocities. We use our findings to aid the design of an experimental micromixer. Using this experimental device, we demonstrate rapid microfluidic mixing over a compact channel length, and validate our numerical simulation results. Finally, we use numerical simulations to study the physical mechanisms leading to microfluidic mixing in our system. Our findings demonstrate a promising method of rapid microfluidic mixing over a short distance, with applications in lab-on-a-chip sample testing.

Chemotactic droplet swimmers in complex geometries

NASA Astrophysics Data System (ADS)

Jin, Chenyu; Hokmabad, Babak V.; Baldwin, Kyle A.; Maass, Corinna C.

2018-02-01

Chemotaxis1 and auto-chemotaxis are key mechanisms in the dynamics of micro-organisms, e.g. in the acquisition of nutrients and in the communication between individuals, influencing the collective behaviour. However, chemical signalling and the natural environment of biological swimmers are generally complex, making them hard to access analytically. We present a well-controlled, tunable artificial model to study chemotaxis and autochemotaxis in complex geometries, using microfluidic assays of self-propelling oil droplets in an aqueous surfactant solution (Herminghaus et al 2014 Soft Matter 10 7008-22 Krüger et al 2016 Phys. Rev. Lett. 117). Droplets propel via interfacial Marangoni stresses powered by micellar solubilisation. Moreover, filled micelles act as a chemical repellent by diffusive phoretic gradient forces. We have studied these chemotactic effects in a series of microfluidic geometries, as published in Jin et al (2017 Proc. Natl Acad. Sci. 114 5089-94): first, droplets are guided along the shortest path through a maze by surfactant diffusing into the maze from the exit. Second, we let auto-chemotactic droplet swimmers pass through bifurcating microfluidic channels and record anticorrelations between the branch choices of consecutive droplets. We present an analytical Langevin model matching the experimental data. In a previously unpublished experiment, pillar arrays of variable sizes and shapes provide a convex wall interacting with the swimmer and, in the case of attachment, bending its trajectory and forcing it to revert to its own trail. We observe different behaviours based on the interplay of wall curvature and negative autochemotaxis, i.e. no attachment for highly curved interfaces, stable trapping at large pillars, and a narrow transition region where negative autochemotaxis makes the swimmers detach after a single orbit.

Miniaturised medium pressure capillary liquid chromatography system with flexible open platform design using off-the-shelf microfluidic components.

PubMed

Li, Yan; Dvořák, Miloš; Nesterenko, Pavel N; Stanley, Roger; Nuchtavorn, Nantana; Krčmová, Lenka Kujovská; Aufartová, Jana; Macka, Mirek

2015-10-08

Trends towards portable analytical instrumentation of the last decades have not been equally reflected in developments of portable liquid chromatography (LC) instrumentation for rapid on-site measurements. A miniaturised medium pressure capillary LC (MPLC) system with gradient elution capability has been designed based on a flexible modular microfluidic system using primarily off-the-shelf low cost components to ensure wide accessibility to other analysts. The microfluidic platform was assembled on a breadboard and contained microsyringe pumps and switch valves, complemented with an injection valve and on-capillary detectors, all controlled by a PC. Four miniaturised microsyringe pumps, with 5, 20 and 100 μL syringe volume options, formed the basis of the pumping system. Two pairs of pumps were used for each mobile phase to create gradient elution capability. The two microsyringe pumps in each pairs were linked by two electrically operated microfluidic switching valves and both pairs of pumps were connected through a zero void volume cross-connector, thus providing a low hold-up volume for gradient formation. Sample was injected by a 20 nL nano-LC sampling valve, directly connected to a 18 cm long 100 μm i.d. Chromolith CapRod RP-18 monolithic capillary column. On-capillary LED-based UV-vis photometric detection was conducted through a piece of equal diameter fused silica capillary connected after the column. The performance of the portable LC system was evaluated theoretically and experimentally, including the maximum operating pressure, gradient mixing performance, and the performance of the detectors. The 5 μL microsyringe pump offered the best performance, with typical maximum operating pressures up to 11.4 ± 0.4 MPa (water) and gradient pumping repeatability of between 4 and 9% for gradients between 0.10% s(-1) and 0.33% s(-1). Test analytes of charged and uncharged dyes and pharmaceuticals of varying hydrophobicity showed typical RSD values of 0.7-1.4% and 3.3-4.8% in isocratic mode and 1.2-4.6% and 3.2-6.4% in gradient mode, respectively for retention time and peak area repeatability. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

Simplified cost models for prefeasibility mineral evaluations

USGS Publications Warehouse

Camm, Thomas W.

1991-01-01

This report contains 2 open pit models, 6 underground mine models, 11 mill models, and cost equations for access roads, power lines, and tailings ponds. In addition, adjustment factors for variation in haulage distances are provided for open pit models and variation in mining depths for underground models.

Design and integration of a generic disposable array-compatible sensor housing into an integrated disposable indirect microfluidic flow injection analysis system.

PubMed

Rapp, Bastian E; Schickling, Benjamin; Prokop, Jürgen; Piotter, Volker; Rapp, Michael; Länge, Kerstin

2011-10-01

We describe an integration strategy for arbitrary sensors intended to be used as biosensors in biomedical or bioanalytical applications. For such devices ease of handling (by a potential end user) as well as strict disposable usage are of importance. Firstly we describe a generic array compatible polymer sensor housing with an effective sample volume of 1.55 μl. This housing leaves the sensitive surface of the sensor accessible for the application of biosensing layers even after the embedding. In a second step we show how this sensor housing can be used in combination with a passive disposable microfluidic chip to set up arbitrary 8-fold sensor arrays and how such a system can be complemented with an indirect microfluidic flow injection analysis (FIA) system. This system is designed in a way that it strictly separates between disposable and reusable components- by introducing tetradecane as an intermediate liquid. This results in a sensor system compatible with the demands of most biomedical applications. Comparative measurements between a classical macroscopic FIA system and this integrated indirect microfluidic system are presented. We use a surface acoustic wave (SAW) sensor as an exemplary detector in this work.

A Soft, Wearable Microfluidic Device for the Capture, Storage, and Colorimetric Sensing of Sweat

PubMed Central

Koh, Ahyeon; Kang, Daeshik; Xue, Yeguang; Lee, Seungmin; Pielak, Rafal M.; Kim, Jeonghyun; Hwang, Taehwan; Min, Seunghwan; Banks, Anthony; Bastien, Philippe; Manco, Megan C.; Wang, Liang; Ammann, Kaitlyn R.; Jang, Kyung-In; Won, Phillip; Han, Seungyong; Ghaffari, Roozbeh; Paik, Ungyu; Slepian, Marvin J.; Balooch, Guive; Huang, Yonggang; Rogers, John A.

2017-01-01

Capabilities in health monitoring via capture and quantitative chemical analysis of sweat could complement, or potentially obviate the need for, approaches based on sporadic assessment of blood samples. Established sweat monitoring technologies use simple fabric swatches and are limited to basic analysis in controlled laboratory or hospital settings. We present a collection of materials and device designs for soft, flexible and stretchable microfluidic systems, including embodiments that integrate wireless communication electronics, which can intimately and robustly bond to the surface of skin without chemical and mechanical irritation. This integration defines access points for a small set of sweat glands such that perspiration spontaneously initiates routing of sweat through a microfluidic network and set of reservoirs. Embedded chemical analyses respond in colorimetric fashion to markers such as chloride and hydronium ions, glucose and lactate. Wireless interfaces to digital image capture hardware serve as a means for quantitation. Human studies demonstrated the functionality of this microfluidic device during fitness cycling in a controlled environment and during long-distance bicycle racing in arid, outdoor conditions. The results include quantitative values for sweat rate, total sweat loss, pH and concentration of both chloride and lactate. PMID:27881826

Vapor and liquid optical monitoring with sculptured Bragg microcavities

NASA Astrophysics Data System (ADS)

Oliva-Ramirez, Manuel; Gil-Rostra, Jorge; López-Santos, Maria C.; González-Elipe, Agustín. R.; Yubero, Francisco

2017-08-01

Sculptured porous Bragg Microcavities (BMs) formed by the successive stacking of columnar SiO2 and TiO2 thin films with zig-zag columnar microstructure are prepared by glancing angle deposition. These BMs act as wavelength dependent optical retarders. This optical behavior is attributed to a self-structuration mechanism involving a fence-bundling association of nanocolumns as observed by Focused Ion Beam Scanning Electron Microscopy. The retardance of these optically active BMs can be modulated by dynamic infiltration of their open porosity with vapors, liquids or solutions with different refractive indices. The tunable birefringence of these nanostructured photonic systems have been successfully simulated with a simple model that assumes that each layer within the BMs stack has uniaxial birefringence. This type of self-associated nanostructures has been incorporated to microfluidic chips for free label vapor and liquid sensing. Several examples of the detection performance of these chips, working either in reflection or transmission configuration, for the optical characterization of vapor and liquids of different refractive index and aqueous solutions of glucose flowing through the microfluidic chips are described.

Population transcriptomics with single-cell resolution: a new field made possible by microfluidics: a technology for high throughput transcript counting and data-driven definition of cell types.

PubMed

Plessy, Charles; Desbois, Linda; Fujii, Teruo; Carninci, Piero

2013-02-01

Tissues contain complex populations of cells. Like countries, which are comprised of mixed populations of people, tissues are not homogeneous. Gene expression studies that analyze entire populations of cells from tissues as a mixture are blind to this diversity. Thus, critical information is lost when studying samples rich in specialized but diverse cells such as tumors, iPS colonies, or brain tissue. High throughput methods are needed to address, model and understand the constitutive and stochastic differences between individual cells. Here, we describe microfluidics technologies that utilize a combination of molecular biology and miniaturized labs on chips to study gene expression at the single cell level. We discuss how the characterization of the transcriptome of each cell in a sample will open a new field in gene expression analysis, population transcriptomics, that will change the academic and biomedical analysis of complex samples by defining them as quantified populations of single cells. Copyright © 2013 WILEY Periodicals, Inc.

A Learned Society's Perspective on Publishing.

PubMed

Suzuki, Kunihiko; Edelson, Alan; Iversen, Leslie L; Hausmann, Laura; Schulz, Jörg B; Turner, Anthony J

2016-10-01

Scientific journals that are owned by a learned society, like the Journal of Neurochemistry (JNC), which is owned by the International Society for Neurochemistry (ISN), benefit the scientific community in that a large proportion of the income is returned to support the scientific mission of the Society. The income generated by the JNC enables the ISN to organize conferences as a platform for members and non-members alike to share their research, supporting researchers particularly in developing countries by travel grants and other funds, and promoting education in student schools. These direct benefits and initiatives for ISN members and non-members distinguish a society journal from pure commerce. However, the world of scholarly publishing is changing rapidly. Open access models have challenged the business model of traditional journal subscription and hence provided free access to publicly funded scientific research. In these models, the manuscript authors pay a publication cost after peer review and acceptance of the manuscript. Over the last decade, numerous new open access journals have been launched and traditional subscription journals have started to offer open access (hybrid journals). However, open access journals follow the general scheme that, of all participating parties, the publisher receives the highest financial benefit. The income is generated by researchers whose positions and research are mostly financed by taxpayers' or funders' money, and by reviewers and editors, who frequently are not reimbursed. Last but not least, the authors pay for the publication of their work after a rigorous and sometimes painful review process. JNC itself has an open access option, at a significantly reduced cost for Society members as an additional benefit. This article provides first-hand insights from two former Editors-in-Chief, Kunihiko Suzuki and Leslie Iversen, about the history of JNC's ownership and about the difficulties and battles fought along the way to its current success and reputation. Scientific journals that are owned by a learned society, like the Journal of Neurochemistry (JNC) which is owned by the International Society for Neurochemistry (ISN), benefit the scientific community in that a large proportion of the income is returned to support the scientific mission of the Society. The income generated by the JNC enables the ISN to organize conferences as a platform for members and non-members alike to share their research, supporting researchers particularly in developing countries by travel grants and other funds, and to promote education in student schools. These direct benefits and initiatives for ISN members and non-members distinguish a society journal from pure commerce. However, the world of scholarly publishing is changing rapidly. Open access models have challenged the business model of traditional journal subscription and hence provide free access to publicly funded scientific research. In these models, the manuscript authors pay a publication cost after peer review and acceptance of the manuscript. Over the last decade, numerous new open access journals have been launched and traditional subscription journals have started to offer open access (hybrid journals). However, open access journals pertain to the general scheme that, of all participating parties, the publisher receives the highest financial benefit. The income is generated by researchers whose positions and research are mostly financed by tax payers' or funders' money, reviewers and editors, who frequently are not reimbursed. Last but not least, the authors pay for the publication of their work after a rigorous and sometimes painful review process. JNC itself has an open access option, at a significantly reduced cost for Society members as an additional benefit. This article provides first-hand insights from a long-standing Editor-in-Chief, Kunihiko Suzuki, about the history of JNC's ownership and about difficulties and battles fought on the way to its current success and reputation today. This article is part of the 60th Anniversary special issue. © 2016 International Society for Neurochemistry.

Openness, Web 2.0 Technology, and Open Science

ERIC Educational Resources Information Center

Peters, Michael A.

2010-01-01

Open science is a term that is being used in the literature to designate a form of science based on open source models or that utilizes principles of open access, open archiving and open publishing to promote scientific communication. Open science increasingly also refers to open governance and more democratized engagement and control of science…

False gold: Safely navigating open access publishing to avoid predatory publishers and journals.

PubMed

McCann, Terence V; Polacsek, Meg

2018-04-01

The aim of this study was to review and discuss predatory open access publishing in the context of nursing and midwifery and develop a set of guidelines that serve as a framework to help clinicians, educators and researchers avoid predatory publishers. Open access publishing is increasingly common across all academic disciplines. However, this publishing model is vulnerable to exploitation by predatory publishers, posing a threat to nursing and midwifery scholarship and practice. Guidelines are needed to help researchers recognize predatory journals and publishers and understand the negative consequences of publishing in them. Discussion paper. A literature search of BioMed Central, CINAHL, MEDLINE with Full Text and PubMed for terms related to predatory publishing, published in the period 2007-2017. Lack of awareness of the risks and pressure to publish in international journals, may result in nursing and midwifery researchers publishing their work in dubious open access journals. Caution should be taken prior to writing and submitting a paper, to avoid predatory publishers. The advantage of open access publishing is that it provides readers with access to peer-reviewed research as soon as it is published online. However, predatory publishers use deceptive methods to exploit open access publishing for their own profit. Clear guidelines are needed to help researchers navigate safely open access publishing. A deeper understanding of the risks of predatory publishing is needed. Clear guidelines should be followed by nursing and midwifery researchers seeking to publish their work in open access journals. © 2017 John Wiley & Sons Ltd.

The current status of alternatives to animal testing and predictive toxicology methods using liver microfluidic biochips.

PubMed

Prot, Jean Matthieu; Leclerc, Eric

2012-06-01

In this paper, we will consider new in vitro cell culture platforms and the progress made, based on the microfluidic liver biochips dedicated to pharmacological and toxicological studies. Particular emphasis will be given to recent developments in the microfluidic tools dedicated to cell culture (more particularly liver cell culture), in silico opportunities for Physiologically Based PharmacoKinetic (PBPK) modelling, the challenge of the mechanistic interpretations offered by the approaches resulting from "multi-omics" data (transcriptomics, proteomics, metabolomics, cytomics) and imaging microfluidic platforms. Finally, we will discuss the critical features regarding microfabrication, design and materials, and cell functionality as the key points for the future development of new microfluidic liver biochips.

Advances in Microfluidic Platforms for Analyzing and Regulating Human Pluripotent Stem Cells

PubMed Central

Qian, Tongcheng; Shusta, Eric V.; Palecek, Sean P.

2015-01-01

Microfluidic devices employ submillimeter length scale control of flow to achieve high-resolution spatial and temporal control over the microenvironment, providing powerful tools to elucidate mechanisms of human pluripotent stem cell (hPSC) regulation and to elicit desired hPSC fates. In addition, microfluidics allow control of paracrine and juxtracrine signaling, thereby enabling fabrication of microphysiological systems comprised of multiple cell types organized into organs-on-a-chip. Microfluidic cell culture systems can also be integrated with actuators and sensors, permitting construction of high-density arrays of cell-based biosensors for screening applications. This review describes recent advances in using microfluidics to understand mechanisms by which the microenvironment regulates hPSC fates and applications of microfluidics to realize the potential of hPSCs for in vitro modeling and screening applications. PMID:26313850

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.

Research highlights: printing the future of microfabrication.

PubMed

Tseng, Peter; Murray, Coleman; Kim, Donghyuk; Di Carlo, Dino

2014-05-07

In this issue we highlight emerging microfabrication approaches suitable for microfluidic systems with a focus on "additive manufacturing" processes (i.e. printing). In parallel with the now-wider availability of low cost consumer-grade 3D printers (as evidenced by at least three brands of 3D printers for sale in a recent visit to an electronics store in Akihabara, Tokyo), commercial-grade 3D printers are ramping to higher and higher resolution with new capabilities, such as printing of multiple materials of different transparency, and with different mechanical and electrical properties. We highlight new work showing that 3D printing (stereolithography approaches in particular) has now risen as a viable technology to print whole microfluidic devices. Printing on 2D surfaces such as paper is an everyday experience, and has been used widely in analytical chemistry for printing conductive materials on paper strips for glucose and other electrochemical sensors. We highlight recent work using electrodes printed on paper for digital microfluidic droplet actuation. Finally, we highlight recent work in which printing of membrane-bound droplets that interconnect through bilayer membranes may open up an entirely new approach to microfluidic manufacturing of soft devices that mimic physiological systems.

A microfluidic direct formate fuel cell on paper.

PubMed

Copenhaver, Thomas S; Purohit, Krutarth H; Domalaon, Kryls; Pham, Linda; Burgess, Brianna J; Manorothkul, Natalie; Galvan, Vicente; Sotez, Samantha; Gomez, Frank A; Haan, John L

2015-08-01

We describe the first direct formate fuel cell on a paper microfluidic platform. In traditional membrane-less microfluidic fuel cells (MFCs), external pumping consumes power produced by the fuel cell in order to maintain co-laminar flow of the anode stream and oxidant stream to prevent mixing. However, in paper microfluidics, capillary action drives flow while minimizing stream mixing. In this work, we demonstrate a paper MFC that uses formate and hydrogen peroxide as the anode fuel and cathode oxidant, respectively. Using these materials we achieve a maximum power density of nearly 2.5 mW/mg Pd. In a series configuration, our MFC achieves an open circuit voltage just over 1 V, and in a parallel configuration, short circuit of 20 mA absolute current. We also demonstrate that the MFC does not require continuous flow of fuel and oxidant to produce power. We found that we can pre-saturate the materials on the paper, stop the electrolyte flow, and still produce approximately 0.5 V for 15 min. This type of paper MFC has potential applications in point-of-care diagnostic devices and other electrochemical sensors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

On-chip micropatterning of plastic (cylic olefin copolymer, COC) microfluidic channels for the fabrication of biomolecule microarrays using photografting methods.

PubMed

Pu, Qiaosheng; Oyesanya, Olufemi; Thompson, Bowlin; Liu, Shantang; Alvarez, Julio C

2007-01-30

This paper reports on the surface modification of plastic microfluidic channels to prepare different biomolecule micropatterns using ultraviolet (UV) photografting methods. The linkage chemistry is based upon UV photopolymerization of acryl monomers to generate thin films (0.01-6 microm) chemically linked to the organic backbone of the plastic surface. The commodity thermoplastic, cyclic olefin copolymer (COC) was selected to build microfluidic chips because of its significant UV transparency and easiness for microfabrication by molding techniques. Once the polyacrylic films were grafted on the COC surface using photomasks, micropatterns of proteins, DNA, and biotinlated conjugates were readily obtained by surface chemical reactions in one or two subsequent steps. The thickness of the photografted films can be tuned from several nanometers up to several micrometers, depending on the reaction conditions. The micropatterned films can be prepared inside the microfluidic channel (on-chip) or on open COC surfaces (off-chip) with densities of functional groups about 10(-7) mol/cm2. Characterization of these films was performed by attenuated-total-reflectance IR spectroscopy, fluorescence microscopy, profilometry, atomic force microscopy, and electrokinetic methods.

Three-dimensional investigations of the threading regime in a microfluidic flow-focusing channel

NASA Astrophysics Data System (ADS)

Gowda, Krishne; Brouzet, Christophe; Lefranc, Thibault; Soderberg, L. Daniel; Lundell, Fredrik

2017-11-01

We study the flow dynamics of the threading regime in a microfluidic flow-focusing channel through 3D numerical simulations and experiments. Making strong filaments from cellulose nano-fibrils (CNF) could potentially steer to new high-performance bio-based composites competing with conventional glass fibre composites. CNF filaments can be obtained through hydrodynamic alignment of dispersed CNF by using the concept of flow-focusing. The aligned structure is locked by diffusion of ions resulting in a dispersion-gel transition. Flow-focusing typically refers to a microfluidic channel system where the core fluid is focused by the two sheath fluids, thereby creating an extensional flow at the intersection. In this study, threading regime corresponds to an extensional flow field generated by the water sheath fluid stretching the dispersed CNF core fluid and leading to formation of long threads. The experimental measurements are performed using optical coherence tomography (OCT) and 3D numerical simulations with OpenFOAM. The prime focus is laid on the 3D characteristics of thread formation such as wetting length of core fluid, shape, aspect ratio of the thread and velocity flow-field in the microfluidic channel.

Quasi-3D Modeling and Efficient Simulation of Laminar Flows in Microfluidic Devices.

PubMed

Islam, Md Zahurul; Tsui, Ying Yin

2016-10-03

A quasi-3D model has been developed to simulate the flow in planar microfluidic systems with low Reynolds numbers. The model was developed by decomposing the flow profile along the height of a microfluidic system into a Fourier series. It was validated against the analytical solution for flow in a straight rectangular channel and the full 3D numerical COMSOL Navier-Stokes solver for flow in a T-channel. Comparable accuracy to the full 3D numerical solution was achieved by using only three Fourier terms with a significant decrease in computation time. The quasi-3D model was used to model flows in a micro-flow cytometer chip on a desktop computer and good agreement between the simulation and the experimental results was found.

Quasi-3D Modeling and Efficient Simulation of Laminar Flows in Microfluidic Devices

PubMed Central

Islam, Md. Zahurul; Tsui, Ying Yin

2016-01-01

A quasi-3D model has been developed to simulate the flow in planar microfluidic systems with low Reynolds numbers. The model was developed by decomposing the flow profile along the height of a microfluidic system into a Fourier series. It was validated against the analytical solution for flow in a straight rectangular channel and the full 3D numerical COMSOL Navier-Stokes solver for flow in a T-channel. Comparable accuracy to the full 3D numerical solution was achieved by using only three Fourier terms with a significant decrease in computation time. The quasi-3D model was used to model flows in a micro-flow cytometer chip on a desktop computer and good agreement between the simulation and the experimental results was found. PMID:27706104

A Microfluidics and Agent-Based Modeling Framework for Investigating Spatial Organization in Bacterial Colonies: The Case of Pseudomonas Aeruginosa and H1-Type VI Secretion Interactions

DOE PAGES

Wilmoth, Jared L.; Doak, Peter W.; Timm, Andrea; ...

2018-02-06

The factors leading to changes in the organization of microbial assemblages at fine spatial scales are not well characterized or understood. However, they are expected to guide the succession of community development and function toward specific outcomes that could impact human health and the environment. In this study, we put forward a combined experimental and agent-based modeling framework and use it to interpret unique spatial organization patterns of H1-Type VI secretion system (T6SS) mutants of P. aeruginosa under spatial confinement. We find that key parameters, such as T6SS-mediated cell contact and lysis, spatial localization, relative species abundance, cell density andmore » local concentrations of growth substrates and metabolites are influenced by spatial confinement. The model, written in the accessible programming language NetLogo, can be adapted to a variety of biological systems of interest and used to simulate experiments across a broad parameter space. It was implemented and run in a high-throughput mode by deploying it across multiple CPUs, with each simulation representing an individual well within a high-throughput microwell array experimental platform. The microfluidics and agent-based modeling framework we present in this paper provides an effective means by which to connect experimental studies in microbiology to model development. The work demonstrates progress in coupling experimental results to simulation while also highlighting potential sources of discrepancies between real-world experiments and idealized models.« less

A Microfluidics and Agent-Based Modeling Framework for Investigating Spatial Organization in Bacterial Colonies: The Case of Pseudomonas Aeruginosa and H1-Type VI Secretion Interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilmoth, Jared L.; Doak, Peter W.; Timm, Andrea

The factors leading to changes in the organization of microbial assemblages at fine spatial scales are not well characterized or understood. However, they are expected to guide the succession of community development and function toward specific outcomes that could impact human health and the environment. In this study, we put forward a combined experimental and agent-based modeling framework and use it to interpret unique spatial organization patterns of H1-Type VI secretion system (T6SS) mutants of P. aeruginosa under spatial confinement. We find that key parameters, such as T6SS-mediated cell contact and lysis, spatial localization, relative species abundance, cell density andmore » local concentrations of growth substrates and metabolites are influenced by spatial confinement. The model, written in the accessible programming language NetLogo, can be adapted to a variety of biological systems of interest and used to simulate experiments across a broad parameter space. It was implemented and run in a high-throughput mode by deploying it across multiple CPUs, with each simulation representing an individual well within a high-throughput microwell array experimental platform. The microfluidics and agent-based modeling framework we present in this paper provides an effective means by which to connect experimental studies in microbiology to model development. The work demonstrates progress in coupling experimental results to simulation while also highlighting potential sources of discrepancies between real-world experiments and idealized models.« less

Microfluidic local perfusion chambers for the visualization and manipulation of synapses

PubMed Central

Taylor, Anne M.; Dieterich, Daniela C.; Ito, Hiroshi T.; Kim, Sally A.; Schuman, Erin M.

2010-01-01

Summary The polarized nature of neurons as well as the size and density of synapses complicates the manipulation and visualization of cell biological processes that control synaptic function. Here we developed a microfluidic local perfusion (μLP) chamber to access and manipulate synaptic regions and pre- and post-synaptic compartments in vitro. This chamber directs the formation of synapses in >100 parallel rows connecting separate neuron populations. A perfusion channel transects the parallel rows allowing access to synaptic regions with high spatial and temporal resolution. We used this chamber to investigate synapse-to-nucleus signaling. Using the calcium indicator dye, Fluo-4, we measured changes in calcium at dendrites and somata, following local perfusion of glutamate. Exploiting the high temporal resolution of the chamber, we exposed synapses to “spaced” or “massed” application of glutamate and then examined levels of pCREB in somata. Lastly, we applied the metabotropic receptor agonist, DHPG, to dendrites and observed increases in Arc transcription and Arc transcript localization. PMID:20399729

Self-formed cylindrical microcapillaries through surface migration of silicon and their application to single-cell analysis

NASA Astrophysics Data System (ADS)

Zeng, Fan; Luo, Yuan; Yobas, Levent; Wong, Man

2013-05-01

Surface migration of monocrystalline silicon has been applied to demonstrate self-formed cylindrical microcapillaries with diameters from 0.8 to 2.8 µm based on the microstructured substrate topography. The microcapillaries are entirely enclosed in silicon and can be conveniently etched to create fluidic access ports and microchannels for their subsequent integration into functional microfluidic devices. Moreover, the microcapillaries can be thermally oxidized through their access ports with silica walls remain intact upon release from surrounding silicon in an effort to enhance optical clarity. Straight microcapillaries and microcapillaries with perpendicular turns and crossings (junctions) have all been fabricated and validated for fluidic continuity with a fluorescein solution pumped through. The utility of the microcapillaries has been showcased on particle traps in which biological cells are probed for single-cell impedance spectroscopy. The approach disclosed, given its full compatibility with semiconductor device fabrication, offers great potential towards intelligent cell and molecule-based devices merging microelectronics and microfluidics.

Microfluidic technology platforms for synthesizing, labeling and measuring the kinetics of transport and biochemical reactions for developing molecular imaging probes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phelps, Michael E.

2009-09-01

Radiotracer techniques are used in environmental sciences, geology, biology and medicine. Radiotracers with Positron Emission Tomography (PET) provided biological examinations of ~3 million patients 2008. Despite the success of positron labeled tracers in many sciences, there is limited access in an affordable and convenient manner to develop and use new tracers. Integrated microfluidic chips are a new technology well matched to the concentrations of tracers. Our goal is to develop microfluidic chips and new synthesis approaches to enable wide dissemination of diverse types of tracers at low cost, and to produce new generations of radiochemists for which there are manymore » unfilled jobs. The program objectives are to: 1. Develop an integrated microfluidic platform technology for synthesizing and 18F-labeling diverse arrays of different classes of molecules. 2. Incorporate microfluidic chips into small PC controlled devices (“Synthesizer”) with a platform interfaced to PC for electronic and fluid input/out control. 3. Establish a de-centralized model with Synthesizers for discovering and producing molecular imaging probes, only requiring delivery of inexpensive [18F]fluoride ion from commercial PET radiopharmacies vs the centralized approach of cyclotron facilities synthesizing and shipping a few different types of 18F-probes. 4. Develop a position sensitive avalanche photo diode (PSAPD) camera for beta particles embedded in a microfluidic chip for imaging and measuring transport and biochemical reaction rates to valid new 18F-labeled probes in an array of cell cultures. These objectives are met within a research and educational program integrating radio-chemistry, synthetic chemistry, biochemistry, engineering and biology in the Crump Institute for Molecular Imaging. The Radiochemistry Training Program exposes PhD and post doctoral students to molecular imaging in vitro in cells and microorganisms in microfluidic chips and in vivo with PET, from new technologies for radiochemistry (macro to micro levels), biochemistry and biology to imaging principles, tracer kinetics, pharmacokinetics and biochemical assays. New generations of radiochemists will be immersed in the biochemistry and biology for which their labeled probes are being developed for assays of these processes. In this program engineers and radio-chemists integrate the principles of microfluidics and radiolabeling along with proper system design and chemistry rule sets to yield Synthesizers enabling biological and pharmaceutical scientists to develop diverse arrays of probes to pursue their interests. This progression would allow also radiochemists to focus on the further evolution of rapid, high yield synthetic reactions with new enabling technologies, rather than everyday production of radiotracers that should be done by technologists. The invention of integrated circuits in electronics established a platform technology that allowed an evolution of ideas and applications far beyond what could have been imagined at the beginning. Rather than provide a technology for the solution to a single problem, it is hoped that microfluidic radiochemistry will be an enabling platform technology for others to solve many problems. As part of this objective, another program goal is to commercialize the technologies that come from this work so that they can be provided to others who wish to use it.« less

Microfluidic 3D models of cancer

PubMed Central

Sung, Kyung Eun; Beebe, David J.

2014-01-01

Despite advances in medicine and biomedical sciences, cancer still remains a major health issue. Complex interactions between tumors and their microenvironment contribute to tumor initiation and progression and also contribute to the development of drug resistant tumor cell populations. The complexity and heterogeneity of tumors and their microenvironment make it challenging to both study and treat cancer. Traditional animal cancer models and in vitro cancer models are limited in their ability to recapitulate human structures and functions, thus hindering the identification of appropriate drug targets and therapeutic strategies. The development and application of microfluidic 3D cancer models has the potential to overcome some of the limitations inherent to traditional models. This review summarizes the progress in microfluidic 3D cancer models, their benefits, and their broad application to basic cancer biology, drug screening, and drug discovery. PMID:25017040

Quality Assurance in Asian Open and Distance Learning: Policies and Implementation

ERIC Educational Resources Information Center

Darojat, Ojat; Nilson, Michelle; Kaufman, David

2015-01-01

Open universities have emerged as an innovative pillar in the expansion of access to higher education participation, with single-mode distance education providers broadening access in many countries through economies of scale supported by large enrolments. These models raise questions about the quality of education provided. This paper reports on…

The Inevitability of Open Access

ERIC Educational Resources Information Center

Lewis, David W.

2012-01-01

Open access (OA) is an alternative business model for the publication of scholarly journals. It makes articles freely available to readers on the Internet and covers the costs associated with publication through means other than subscriptions. This article argues that Gold OA, where all of the articles of a journal are available at the time of…

High-throughput rare cell separation from blood samples using steric hindrance and inertial microfluidics.

PubMed

Shen, Shaofei; Ma, Chao; Zhao, Lei; Wang, Yaolei; Wang, Jian-Chun; Xu, Juan; Li, Tianbao; Pang, Long; Wang, Jinyi

2014-07-21

The presence and quantity of rare cells in the bloodstream of cancer patients provide a potentially accessible source for the early detection of invasive cancer and for monitoring the treatment of advanced diseases. The separation of rare cells from peripheral blood, as a "virtual and real-time liquid biopsy", is expected to replace conventional tissue biopsies of metastatic tumors for therapy guidance. However, technical obstacles, similar to looking for a needle in a haystack, have hindered the broad clinical utility of this method. In this study, we developed a multistage microfluidic device for continuous label-free separation and enrichment of rare cells from blood samples based on cell size and deformability. We successfully separated tumor cells (MCF-7 and HeLa cells) and leukemic (K562) cells spiked in diluted whole blood using a unique complementary combination of inertial microfluidics and steric hindrance in a microfluidic system. The processing parameters of the inertial focusing and steric hindrance regions were optimized to achieve high-throughput and high-efficiency separation, significant advantages compared with existing rare cell isolation technologies. The results from experiments with rare cells spiked in 1% hematocrit blood indicated >90% cell recovery at a throughput of 2.24 × 10(7) cells min(-1). The enrichment of rare cells was >2.02 × 10(5)-fold. Thus, this microfluidic system driven by purely hydrodynamic forces has practical potential to be applied either alone or as a sample preparation platform for fundamental studies and clinical applications.

‘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.

Electric field-decoupled electroosmotic pump for microfluidic devices.

PubMed

Liu, Shaorong; Pu, Qiaosheng; Lu, Joann J

2003-09-26

An electric field-free electroosmotic pump has been constructed and its pumping rate has been measured under various experimental conditions. The key component of the pump is an ion-exchange membrane grounding joint that serves two major functions: (i) to maintain fluid continuity between pump channels and microfluidic conduit and (ii) to ground the solution in the microfluidic channel at the joint through an external electrode, and hence to decouple the electric field applied to the pump channels from the rest of the microfluidic system. A theoretical model has been developed to calculate the pumping rates and its validity has been demonstrated.

A PDMS/paper/glass hybrid microfluidic biochip integrated with aptamer-functionalized graphene oxide nano-biosensors for one-step multiplexed pathogen detection.

PubMed

Zuo, Peng; Li, XiuJun; Dominguez, Delfina C; Ye, Bang-Ce

2013-10-07

Infectious pathogens often cause serious public health concerns throughout the world. There is an increasing demand for simple, rapid and sensitive approaches for multiplexed pathogen detection. In this paper we have developed a polydimethylsiloxane (PDMS)/paper/glass hybrid microfluidic system integrated with aptamer-functionalized graphene oxide (GO) nano-biosensors for simple, one-step, multiplexed pathogen detection. The paper substrate used in this hybrid microfluidic system facilitated the integration of aptamer biosensors on the microfluidic biochip, and avoided complicated surface treatment and aptamer probe immobilization in a PDMS or glass-only microfluidic system. Lactobacillus acidophilus was used as a bacterium model to develop the microfluidic platform with a detection limit of 11.0 cfu mL(-1). We have also successfully extended this method to the simultaneous detection of two infectious pathogens - Staphylococcus aureus and Salmonella enterica. This method is simple and fast. The one-step 'turn on' pathogen assay in a ready-to-use microfluidic device only takes ~10 min to complete on the biochip. Furthermore, this microfluidic device has great potential in rapid detection of a wide variety of different other bacterial and viral pathogens.

A PDMS/paper/glass hybrid microfluidic biochip integrated with aptamer-functionalized graphene oxide nano-biosensors for one-step multiplexed pathogen detection

PubMed Central

Zuo, Peng; Dominguez, Delfina C.; Ye, Bang-Ce

2014-01-01

Infectious pathogens often cause serious public health concerns throughout the world. There is an increasing demand for simple, rapid and sensitive approaches for multiplexed pathogen detection. In this paper we have developed a polydimethylsiloxane (PDMS)/paper/glass hybrid microfluidic system integrated with aptamer-functionalized graphene oxide (GO) nano-biosensors for simple, one-step, multiplexed pathogen detection. The paper substrate used in this hybrid microfluidic system facilitated the integration of aptamer biosensors on the microfluidic biochip, and avoided complicated surface treatment and aptamer probe immobilization in a PDMS or glass-only microfluidic system. Lactobacillus acidophilus was used as a bacterium model to develop the microfluidic platform with a detection limit of 11.0 cfu mL−1. We have also successfully extended this method to the simultaneous detection of two infectious pathogens - Staphylococcus aureus and Salmonella enterica. This method is simple and fast. The one-step ‘turn on’ pathogen assay in a ready-to-use microfluidic device only takes ~10 min to complete on the biochip. Furthermore, this microfluidic device has great potential in rapid detection of a wide variety of different other bacterial and viral pathogens. PMID:23929394

A neuron-in-capillary platform for facile collection and mass spectrometric characterization of a secreted neuropeptide

PubMed Central

Lee, Chang Young; Fan, Yi; Rubakhin, Stanislav S.; Yoon, Sook; Sweedler, Jonathan V.

2016-01-01

The integration of microfluidic devices—which efficiently handle small liquid volumes—with separations/mass spectrometry (MS) is an effective approach for profiling the neurochemistry occurring in selected neurons. Interfacing the microfluidic cell culture to the mass spectrometer is challenging because of geometric and scaling issues. Here we demonstrate the hyphenation of a neuron-in-capillary platform to a solid phase extraction device and off-line MS. A primary neuronal culture of Aplysia californica neurons was established directly inside a cylindrical polyimide capillary. The approach also uses a particle-embedded monolith to condition neuropeptide releasates collected from several Aplysia neurons cultured in the capillary, with the subsequent characterization of released peptides via MS. This system presents a number of advances compared to more traditional microfluidic devices fabricated with polydimethylsiloxane. These include low cost, easy access to cell culture, rigidity, ease of transport, and minimal fluid handling. The cylindrical geometry of the platform allows convenient interface with a wide range of analytical tools that utilize capillary columns. PMID:27245782

Droplet-based biosensing for lab-on-a-chip, open microfluidics platforms

USDA-ARS?s Scientific Manuscript database

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. La...

Exploring Possibilities for Transforming Established Subscription-based Scientific Journals into Open Access Journals. Present Situation, Transformation Criteria, and Exemplary Implementation within Trans-O-MIM.

PubMed

Haux, Reinhold; Kuballa, Stefanie; Schulze, Mareike; Böhm, Claudia; Gefeller, Olaf; Haaf, Jan; Henning, Peter; Mielke, Corinna; Niggemann, Florian; Schürg, Andrea; Bergemann, Dieter

2016-12-07

Based on today's information and communication technologies the open access paradigm has become an important approach for adequately communicating new scientific knowledge. Summarizing the present situation for journal transformation. Presenting criteria for adequate transformation as well as a specific approach for it. Describing our exemplary implementation of such a journal transformation. Studying the respective literature as well as discussing this topic in various discussion groups and meetings (primarily of editors and publishers, but also of authors and readers), with long term experience as editors and /or publishers of scientific publications as prerequisite. There is a clear will, particularly of political and funding organizations, towards open access publishing. In spite of this, there is still a large amount of scientific knowledge, being communicated through subscription-based journals. For successfully transforming such journals into open access, sixteen criteria for a goal-oriented, stepwise, sustainable, and fair transformation are suggested. The Tandem Model as transformation approach is introduced. Our exemplary implementation is done in the Trans-O-MIM project. It is exploring strategies, models and evaluation metrics for journal transformation. As instance the journal Methods of Information in Medicine will apply the Tandem Model from 2017 onwards. Within Trans-O-MIM we will reach at least nine of the sixteen criteria for adequate transformation. It was positive to implement Trans-O-MIM as international research project. After first steps for transforming Methods have successfully been made, challenges will remain, among others, in identifying appropriate incentives for open access publishing in order to support its transformation.

A light writable microfluidic "flash memory": optically addressed actuator array with latched operation for microfluidic applications.

PubMed

Hua, Zhishan; Pal, Rohit; Srivannavit, Onnop; Burns, Mark A; Gulari, Erdogan

2008-03-01

This paper presents a novel optically addressed microactuator array (microfluidic "flash memory") with latched operation. Analogous to the address-data bus mediated memory address protocol in electronics, the microactuator array consists of individual phase-change based actuators addressed by localized heating through focused light patterns (address bus), which can be provided by a modified projector or high power laser pointer. A common pressure manifold (data bus) for the entire array is used to generate large deflections of the phase change actuators in the molten phase. The use of phase change material as the working media enables latched operation of the actuator array. After the initial light "writing" during which the phase is temporarily changed to molten, the actuated status is self-maintained by the solid phase of the actuator without power and pressure inputs. The microfluidic flash memory can be re-configured by a new light illumination pattern and common pressure signal. The proposed approach can achieve actuation of arbitrary units in a large-scale array without the need for complex external equipment such as solenoid valves and electrical modules, which leads to significantly simplified system implementation and compact system size. The proposed work therefore provides a flexible, energy-efficient, and low cost multiplexing solution for microfluidic applications based on physical displacements. As an example, the use of the latched microactuator array as "normally closed" or "normally open" microvalves is demonstrated. The phase-change wax is fully encapsulated and thus immune from contamination issues in fluidic environments.

Resolution improvement of 3D stereo-lithography through the direct laser trajectory programming: Application to microfluidic deterministic lateral displacement device.

PubMed

Juskova, Petra; Ollitrault, Alexis; Serra, Marco; Viovy, Jean-Louis; Malaquin, Laurent

2018-02-13

The vast majority of current microfluidic devices are produced using soft lithography, a technique with strong limitations regarding the fabrication of three-dimensional architectures. Additive manufacturing holds great promises to overcome these limitations, but conventional machines still lack the resolution required by most microfluidic applications. 3D printing machines based on two-photon lasers, in contrast, have the needed resolution but are too limited in speed and size of the global device. Here we demonstrate how the resolution of conventional stereolithographic machines can be improved by a direct programming of the laser path and can contribute to bridge the gap between the two above technologies, allowing the direct printing of features between 10 and 100 μm, corresponding to a large fraction of microfluidic applications. This strategy allows to achieve resolutions limited only by the physical size of the laser beam, decreasing by a factor at least 2× the size of the smallest features printable, and increasing their reproducibility by a factor 5. The approach was applied to produce an open microfluidic device with the reversible seal, integrating periodical patterns using the simple motifs, and validated by the fabrication of a deterministic lateral displacement particles sorting device. The sorting of polystyrene beads (diameter: 20 μm and 45 μm) was achieved with a specificity >95%, comparable with that achieved with arrays prepared by microlithography. Copyright © 2017 Elsevier B.V. All rights reserved.

Pneumatic oscillator circuits for timing and control of integrated microfluidics.

PubMed

Duncan, Philip N; Nguyen, Transon V; Hui, Elliot E

2013-11-05

Frequency references are fundamental to most digital systems, providing the basis for process synchronization, timing of outputs, and waveform synthesis. Recently, there has been growing interest in digital logic systems that are constructed out of microfluidics rather than electronics, as a possible means toward fully integrated laboratory-on-a-chip systems that do not require any external control apparatus. However, the full realization of this goal has not been possible due to the lack of on-chip frequency references, thus requiring timing signals to be provided from off-chip. Although microfluidic oscillators have been demonstrated, there have been no reported efforts to characterize, model, or optimize timing accuracy, which is the fundamental metric of a clock. Here, we report pneumatic ring oscillator circuits built from microfluidic valves and channels. Further, we present a compressible-flow analysis that differs fundamentally from conventional circuit theory, and we show the utility of this physically based model for the optimization of oscillator stability. Finally, we leverage microfluidic clocks to demonstrate circuits for the generation of phase-shifted waveforms, self-driving peristaltic pumps, and frequency division. Thus, pneumatic oscillators can serve as on-chip frequency references for microfluidic digital logic circuits. On-chip clocks and pumps both constitute critical building blocks on the path toward achieving autonomous laboratory-on-a-chip devices.

Endothelial cell culture in microfluidic devices for investigating microvascular processes.

PubMed

Mannino, Robert G; Qiu, Yongzhi; Lam, Wilbur A

2018-07-01

Numerous conditions and disease states such as sickle cell disease, malaria, thrombotic microangiopathy, and stroke significantly impact the microvasculature function and its role in disease progression. Understanding the role of cellular interactions and microvascular hemodynamic forces in the context of disease is crucial to understanding disease pathophysiology. In vivo models of microvascular disease using animal models often coupled with intravital microscopy have long been utilized to investigate microvascular phenomena. However, these methods suffer from some major drawbacks, including the inability to tightly and quantitatively control experimental conditions, the difficulty of imaging multiple microvascular beds within a living organism, and the inability to isolate specific microvascular geometries such as bifurcations. Thus, there exists a need for in vitro microvascular models that can mitigate the drawbacks associated with in vivo systems. To that end, microfluidics has been widely used to develop such models, as it allows for tight control of system inputs, facile imaging, and the ability to develop robust and repeatable systems with well-defined geometries. Incorporating endothelial cells to branching microfluidic models allows for the development of "endothelialized" systems that accurately recapitulate physiological microvessels. In this review, we summarize the field of endothelialized microfluidics, specifically focusing on fabrication methods, limitations, and applications of these systems. We then speculate on future directions and applications of these cutting edge technologies. We believe that this review of the field is of importance to vascular biologists and bioengineers who aim to utilize microfluidic technologies to solve vascular problems.

Operational Experience of an Open-Access, Subscription-Based Mass Spectrometry and Proteomics Facility.

PubMed

Williamson, Nicholas A

2018-03-01

This paper discusses the successful adoption of a subscription-based, open-access model of service delivery for a mass spectrometry and proteomics facility. In 2009, the Mass Spectrometry and Proteomics Facility at the University of Melbourne (Australia) moved away from the standard fee for service model of service provision. Instead, the facility adopted a subscription- or membership-based, open-access model of service delivery. For a low fixed yearly cost, users could directly operate the instrumentation but, more importantly, there were no limits on usage other than the necessity to share available instrument time with all other users. All necessary training from platform staff and many of the base reagents were also provided as part of the membership cost. These changes proved to be very successful in terms of financial outcomes for the facility, instrument access and usage, and overall research output. This article describes the systems put in place as well as the overall successes and challenges associated with the operation of a mass spectrometry/proteomics core in this manner. Graphical abstract ᅟ.

Operational Experience of an Open-Access, Subscription-Based Mass Spectrometry and Proteomics Facility

NASA Astrophysics Data System (ADS)

Williamson, Nicholas A.

2018-03-01

This paper discusses the successful adoption of a subscription-based, open-access model of service delivery for a mass spectrometry and proteomics facility. In 2009, the Mass Spectrometry and Proteomics Facility at the University of Melbourne (Australia) moved away from the standard fee for service model of service provision. Instead, the facility adopted a subscription- or membership-based, open-access model of service delivery. For a low fixed yearly cost, users could directly operate the instrumentation but, more importantly, there were no limits on usage other than the necessity to share available instrument time with all other users. All necessary training from platform staff and many of the base reagents were also provided as part of the membership cost. These changes proved to be very successful in terms of financial outcomes for the facility, instrument access and usage, and overall research output. This article describes the systems put in place as well as the overall successes and challenges associated with the operation of a mass spectrometry/proteomics core in this manner. [Figure not available: see fulltext.

Predicting Droplet Formation on Centrifugal Microfluidic Platforms

NASA Astrophysics Data System (ADS)

Moebius, Jacob Alfred

Centrifugal microfluidics is a widely known research tool for biological sample and water quality analysis. Currently, the standard equipment used for such diagnostic applications include slow, bulky machines controlled by multiple operators. These machines can be condensed into a smaller, faster benchtop sample-to-answer system. Sample processing is an important step taken to extract, isolate, and convert biological factors, such as nucleic acids or proteins, from a raw sample to an analyzable solution. Volume definition is one such step. The focus of this thesis is the development of a model predicting monodispersed droplet formation and the application of droplets as a technique for volume definition. First, a background of droplet microfluidic platforms is presented, along with current biological analysis technologies and the advantages of integrating such technologies onto microfluidic platforms. Second, background and theories of centrifugal microfluidics is given, followed by theories relevant to droplet emulsions. Third, fabrication techniques for centrifugal microfluidic designs are discussed. Finally, the development of a model for predicting droplet formation on the centrifugal microfluidic platform are presented for the rest of the thesis. Predicting droplet formation analytically based on the volumetric flow rates of the continuous and dispersed phases, the ratios of these two flow rates, and the interfacial tension between the continuous and dispersed phases presented many challenges, which will be discussed in this work. Experimental validation was completed using continuous phase solutions of different interfacial tensions. To conclude, prospective applications are discussed with expected challenges.

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

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.

Droplet microfluidics with magnetic beads: a new tool to investigate drug-protein interactions.

PubMed

Lombardi, Dario; Dittrich, Petra S

2011-01-01

In this study, we give the proof of concept for a method to determine binding constants of compounds in solution. By implementing a technique based on magnetic beads with a microfluidic device for segmented flow generation, we demonstrate, for individual droplets, fast, robust and complete separation of the magnetic beads. The beads are used as a carrier for one binding partner and hence, any bound molecule is separated likewise, while the segmentation into small microdroplets ensures fast mixing, and opens future prospects for droplet-wise analysis of drug candidate libraries. We employ the method for characterization of drug-protein binding, here warfarin to human serum albumin. The approach lays the basis for a microfluidic droplet-based screening device aimed at investigating the interactions of drugs with specific targets including enzymes and cells. Furthermore, the continuous method could be employed for various applications, such as binding assays, kinetic studies, and single cell analysis, in which rapid removal of a reactive component is required.

Microfluidic Bead Suspension Hopper

PubMed Central

2014-01-01

Many high-throughput analytical platforms, from next-generation DNA sequencing to drug discovery, rely on beads as carriers of molecular diversity. Microfluidic systems are ideally suited to handle and analyze such bead libraries with high precision and at minute volume scales; however, the challenge of introducing bead suspensions into devices before they sediment usually confounds microfluidic handling and analysis. We developed a bead suspension hopper that exploits sedimentation to load beads into a microfluidic droplet generator. A suspension hopper continuously delivered synthesis resin beads (17 μm diameter, 112,000 over 2.67 h) functionalized with a photolabile linker and pepstatin A into picoliter-scale droplets of an HIV-1 protease activity assay to model ultraminiaturized compound screening. Likewise, trypsinogen template DNA-coated magnetic beads (2.8 μm diameter, 176,000 over 5.5 h) were loaded into droplets of an in vitro transcription/translation system to model a protein evolution experiment. The suspension hopper should effectively remove any barriers to using suspensions as sample inputs, paving the way for microfluidic automation to replace robotic library distribution. PMID:24761972

Virtual Hubs for facilitating access to Open Data

NASA Astrophysics Data System (ADS)

Mazzetti, Paolo; Latre, Miguel Á.; Ernst, Julia; Brumana, Raffaella; Brauman, Stefan; Nativi, Stefano

2015-04-01

In October 2014 the ENERGIC-OD (European NEtwork for Redistributing Geospatial Information to user Communities - Open Data) project, funded by the European Union under the Competitiveness and Innovation framework Programme (CIP), has started. In response to the EU call, the general objective of the project is to "facilitate the use of open (freely available) geographic data from different sources for the creation of innovative applications and services through the creation of Virtual Hubs". In ENERGIC-OD, Virtual Hubs are conceived as information systems supporting the full life cycle of Open Data: publishing, discovery and access. They facilitate the use of Open Data by lowering and possibly removing the main barriers which hampers geo-information (GI) usage by end-users and application developers. Data and data services heterogeneity is recognized as one of the major barriers to Open Data (re-)use. It imposes end-users and developers to spend a lot of effort in accessing different infrastructures and harmonizing datasets. Such heterogeneity cannot be completely removed through the adoption of standard specifications for service interfaces, metadata and data models, since different infrastructures adopt different standards to answer to specific challenges and to address specific use-cases. Thus, beyond a certain extent, heterogeneity is irreducible especially in interdisciplinary contexts. ENERGIC-OD Virtual Hubs address heterogeneity adopting a mediation and brokering approach: specific components (brokers) are dedicated to harmonize service interfaces, metadata and data models, enabling seamless discovery and access to heterogeneous infrastructures and datasets. As an innovation project, ENERGIC-OD will integrate several existing technologies to implement Virtual Hubs as single points of access to geospatial datasets provided by new or existing platforms and infrastructures, including INSPIRE-compliant systems and Copernicus services. ENERGIC OD will deploy a set of five Virtual Hubs (VHs) at national level in France, Germany, Italy, Poland, Spain and an additional one at the European level. VHs will be provided according to the cloud Software-as-a-Services model. The main expected impact of VHs is the creation of new business opportunities opening up access to Research Data and Public Sector Information. Therefore, ENERGIC-OD addresses not only end-users, who will have the opportunity to access the VH through a geo-portal, but also application developers who will be able to access VH functionalities through simple Application Programming Interfaces (API). ENERGIC-OD Consortium will develop ten different applications on top of the deployed VHs. They aim to demonstrate how VHs facilitate the development of new and multidisciplinary applications based on the full exploitation of (open) GI, hence stimulating innovation and business activities.

A soft, wearable microfluidic device for the capture, storage, and colorimetric sensing of sweat.

PubMed

Koh, Ahyeon; Kang, Daeshik; Xue, Yeguang; Lee, Seungmin; Pielak, Rafal M; Kim, Jeonghyun; Hwang, Taehwan; Min, Seunghwan; Banks, Anthony; Bastien, Philippe; Manco, Megan C; Wang, Liang; Ammann, Kaitlyn R; Jang, Kyung-In; Won, Phillip; Han, Seungyong; Ghaffari, Roozbeh; Paik, Ungyu; Slepian, Marvin J; Balooch, Guive; Huang, Yonggang; Rogers, John A

2016-11-23

Capabilities in health monitoring enabled by capture and quantitative chemical analysis of sweat could complement, or potentially obviate the need for, approaches based on sporadic assessment of blood samples. Established sweat monitoring technologies use simple fabric swatches and are limited to basic analysis in controlled laboratory or hospital settings. We present a collection of materials and device designs for soft, flexible, and stretchable microfluidic systems, including embodiments that integrate wireless communication electronics, which can intimately and robustly bond to the surface of the skin without chemical and mechanical irritation. This integration defines access points for a small set of sweat glands such that perspiration spontaneously initiates routing of sweat through a microfluidic network and set of reservoirs. Embedded chemical analyses respond in colorimetric fashion to markers such as chloride and hydronium ions, glucose, and lactate. Wireless interfaces to digital image capture hardware serve as a means for quantitation. Human studies demonstrated the functionality of this microfluidic device during fitness cycling in a controlled environment and during long-distance bicycle racing in arid, outdoor conditions. The results include quantitative values for sweat rate, total sweat loss, pH, and concentration of chloride and lactate. Copyright © 2016, American Association for the Advancement of Science.

Using a patterned grating structure to create lipid bilayer platforms insensitive to air bubbles.

PubMed

Han, Chung-Ta; Chao, Ling

2015-01-07

Supported lipid bilayers (SLBs) have been used for various biosensing applications. The bilayer structure enables embedded lipid membrane species to maintain their native orientation, and the two-dimensional fluidity is crucial for numerous biomolecular interactions to occur. The platform integrated with a microfluidic device for reagent transport and exchange has great potential to be applied with surface analytical tools. However, SLBs can easily be destroyed by air bubbles during assay reagent transport and exchange. Here, we created a patterned obstacle grating structured surface in a microfluidic channel to protect SLBs from being destroyed by air bubbles. Unlike all of the previous approaches using chemical modification or adding protection layers to strengthen lipid bilayers, the uniqueness of this approach is that it uses the patterned obstacles to physically trap water above the bilayers to prevent the air-water interface from directly coming into contact with and peeling the bilayers. We showed that our platform with certain grating geometry criteria can provide promising protection to SLBs from air bubbles. The required obstacle distance was found to decrease when we increased the air-bubble movement speed. In addition, the interaction assay results from streptavidin and biotinylated lipids in the confined SLBs suggested that receptors at the SLBs retained the interaction ability after air-bubble treatment. The results showed that the developed SLB platform can preserve both high membrane fluidity and high accessibility to the outside environment, which have never been simultaneously achieved before. Incorporating the built platforms with some surface analytical tools could open the bottleneck of building highly robust in vitro cell-membrane-related bioassays.

Numerical design and optimization of hydraulic resistance and wall shear stress inside pressure-driven microfluidic networks.

PubMed

Damiri, Hazem Salim; Bardaweel, Hamzeh Khalid

2015-11-07

Microfluidic networks represent the milestone of microfluidic devices. Recent advancements in microfluidic technologies mandate complex designs where both hydraulic resistance and pressure drop across the microfluidic network are minimized, while wall shear stress is precisely mapped throughout the network. In this work, a combination of theoretical and modeling techniques is used to construct a microfluidic network that operates under minimum hydraulic resistance and minimum pressure drop while constraining wall shear stress throughout the network. The results show that in order to minimize the hydraulic resistance and pressure drop throughout the network while maintaining constant wall shear stress throughout the network, geometric and shape conditions related to the compactness and aspect ratio of the parent and daughter branches must be followed. Also, results suggest that while a "local" minimum hydraulic resistance can be achieved for a geometry with an arbitrary aspect ratio, a "global" minimum hydraulic resistance occurs only when the aspect ratio of that geometry is set to unity. Thus, it is concluded that square and equilateral triangular cross-sectional area microfluidic networks have the least resistance compared to all rectangular and isosceles triangular cross-sectional microfluidic networks, respectively. Precise control over wall shear stress through the bifurcations of the microfluidic network is demonstrated in this work. Three multi-generation microfluidic network designs are considered. In these three designs, wall shear stress in the microfluidic network is successfully kept constant, increased in the daughter-branch direction, or decreased in the daughter-branch direction, respectively. For the multi-generation microfluidic network with constant wall shear stress, the design guidelines presented in this work result in identical profiles of wall shear stresses not only within a single generation but also through all the generations of the microfluidic network under investigation. The results obtained in this work are consistent with previously reported data and suitable for a wide range of lab-on-chip applications.

Breast Cancer Tissue Bioreactor for Direct Interrogation and Observation of Response to Antitumor Therapies

DTIC Science & Technology

2012-07-01

regulate microfluidic flow rates within the TTB, including flow channel height variation and incorporation of valves (see Figure 2 and Supplemental...cartridge. As an alternative to individual channel TURN valve -adjusted flow regulators, we investigated use of pre-fabricated microfluidic flow resistance...Small Parts, Inc. and B) Microfluidic manifolds with built-in TURN valves . Supplemental Figure S3. Simplified 2D and 3D diffusional model

Effective Thermo-Capillary Mixing in Droplet Microfluidics Integrated with a Microwave Heater.

PubMed

Yesiloz, Gurkan; Boybay, Muhammed S; Ren, Carolyn L

2017-02-07

In this study, we present a microwave-based microfluidic mixer that allows rapid mixing within individual droplets efficiently. The designed microwave mixer is a coplanar design with a small footprint, which is fabricated on a glass substrate and integrated with a microfluidic chip. The mixer works essentially as a resonator that accumulates an intensive electromagnetic field into a spiral capacitive gap (around 200 μm), which provides sufficient energy to heat-up droplets that pass through the capacitive gap. This microwave actuation induces nonuniform Marangoni stresses on the interface, which results in three-dimensional motion inside the droplet and thus fast mixing. In order to evaluate the performance of the microwave mixer, droplets with highly viscous fluid, 75% (w/w) glycerol solution, were generated, half of which were seeded with fluorescent dye for imaging purposes. The relative importance of different driving forces for mixing was evaluated qualitatively using magnitude analysis, and the effect of the applied power on mixing performance was also investigated. Mixing efficiency was quantified using the mixing index, which shows as high as 97% mixing efficiency was achieved within the range of milliseconds. This work demonstrates a very unique approach of utilizing microwave technology to facilitate mixing in droplet microfluidics systems, which can potentially open up areas for biochemical synthesis applications.

Smoke and Emissions Model Intercomparison Project (SEMIP)

NASA Astrophysics Data System (ADS)

Larkin, N. K.; Raffuse, S.; Strand, T.; Solomon, R.; Sullivan, D.; Wheeler, N.

2008-12-01

Fire emissions and smoke impacts from wildland fire are a growing concern due to increasing fire season severity, dwindling tolerance of smoke by the public, tightening air quality regulations, and their role in climate change issues. Unfortunately, while a number of models and modeling system solutions are available to address these issues, the lack of quantitative information on the limitations and difference between smoke and emissions models impedes the use of these tools for real-world applications (JFSP, 2007). We describe a new, open-access project to directly address this issue, the open-access Smoke Emissions Model Intercomparison Project (SEMIP) and invite the community to participate. Preliminary work utilizing the modular BlueSky framework to directly compare fire location and size information, fuel loading amounts, fuel consumption rates, and fire emissions from a number of current models that has found model-to-model variability as high as two orders of magnitude for an individual fire. Fire emissions inventories also show significant variability on both regional and national scales that are dependant on the fire location information used (ground report vs. satellite), the fuel loading maps assumed, and the fire consumption models employed. SEMIP expands on this work and creates an open-access database of model results and observations with the goal of furthering model development and model prediction usability for real-world decision support.

Quantum game theory and open access publishing

NASA Astrophysics Data System (ADS)

Hanauske, Matthias; Bernius, Steffen; Dugall, Berndt

2007-08-01

The digital revolution of the information age and in particular the sweeping changes of scientific communication brought about by computing and novel communication technology, potentiate global, high grade scientific information for free. The arXiv, for example, is the leading scientific communication platform, mainly for mathematics and physics, where everyone in the world has free access on. While in some scientific disciplines the open access way is successfully realized, other disciplines (e.g. humanities and social sciences) dwell on the traditional path, even though many scientists belonging to these communities approve the open access principle. In this paper we try to explain these different publication patterns by using a game theoretical approach. Based on the assumption, that the main goal of scientists is the maximization of their reputation, we model different possible game settings, namely a zero sum game, the prisoners’ dilemma case and a version of the stag hunt game, that show the dilemma of scientists belonging to “non-open access communities”. From an individual perspective, they have no incentive to deviate from the Nash equilibrium of traditional publishing. By extending the model using the quantum game theory approach it can be shown, that if the strength of entanglement exceeds a certain value, the scientists will overcome the dilemma and terminate to publish only traditionally in all three settings.

Open access to an outpatient intravenous diuresis program in a systolic heart failure disease management program.

PubMed

Hebert, Kathy; Dias, Andre; Franco, Emiliana; Tamariz, Leonardo; Steen, Dylan; Arcement, Lee M

2011-01-01

In order to provide efficient utilization of resources in an outpatient setting for acute exacerbation of heart failure (HF), the authors piloted an open-access outpatient intravenous (IV) diuretic program (IVDP) to evaluate utilization in an HF disease management program (HFDMP), patient characteristics for users of the program, and safety. An outpatient HFDMP at Jackson Memorial Hospital in Miami, Florida, enrolling 577 patients 18 years and older with an ejection fraction ≤40% was implemented. For symptoms or weight gain ≥5 pounds, patients were eligible to use an open-access IVDP during clinic hours. A total of 130 HFDM patients (22.5%) used the IVDP. IVDP users were more likely to be diabetic, with lower body mass indices than non-IVDP users. New York Heart Association class IV patients and previously hospitalized patients were more likely to use the IVDP. There were no documented adverse reactions for patients receiving treatment and no difference in mortality between groups. This open-access outpatient IVDP model for patients with HF was readily utilized by the HFDMP participants and appears safe for use in this population. This unique model may provide alternative access for acute HF treatment. Congest Heart Fail. © 2011 Wiley Periodicals, Inc.

A wireless sequentially actuated microvalve system

NASA Astrophysics Data System (ADS)

Baek, Seung-Ki; Yoon, Yong-Kyu; Jeon, Hye-Seon; Seo, Soonmin; Park, Jung-Hwan

2013-04-01

A wireless microvalve system was fabricated based on induction heating for flow control in microfluidics by sequential valve opening. In this approach, we used paraffin wax as a flow plug, which can be changed from solid to liquid with adjacent heating elements operated by induction heating. Programmable opening of valves was devised by using different thermal responses of metal discs to a magnetic field. Copper and nickel discs with a diameter of 2.5 mm and various thicknesses (50, 100 and 200 µm) were prepared as heating elements by a laser cutting method, and they were integrated in the microfluidic channel as part of the microvalve. A calorimetric test was used to measure the thermal properties of the discs in terms of kinds of metal and disc thickness. Sequential openings of the microvalves were performed using the difference in the thermal response of 100 µm thick copper disc and 50 µm thick nickel disc for short-interval openings and 200 µm thick copper disc and 100-µm-thick nickel disc for long-interval openings. The thermal effect on fluid samples as a result of induction heating of the discs was studied by investigating lysozyme denaturation. More heat was generated in heating elements made of copper than in those made of nickel, implying differences in the thermal response of heating elements made of copper and nickel. Also, the thickness of the heating elements affected the thermal response in the elements. Valve openings for short intervals of 1-5 s and long intervals of 15-23 s were achieved by using two sets of heating elements. There was no significant change in lysozyme activity by increasing the temperature of the heating discs. This study demonstrates that a wireless sequentially actuated microvalve system can provide programmed valve opening, portability, ease of fabrication and operation, disposability, and low cost.

Application of Microfluidics in Experimental Ecology: The Importance of Being Spatial.

PubMed

Nagy, Krisztina; Ábrahám, Ágnes; Keymer, Juan E; Galajda, Péter

2018-01-01

Microfluidics is an emerging technology that is used more and more in biology experiments. Its capabilities of creating precisely controlled conditions in cellular dimensions make it ideal to explore cell-cell and cell-environment interactions. Thus, a wide spectrum of problems in microbial ecology can be studied using engineered microbial habitats. Moreover, artificial microfluidic ecosystems can serve as model systems to test ecology theories and principles that apply on a higher level in the hierarchy of biological organization. In this mini review we aim to demonstrate the versatility of microfluidics and the diversity of its applications that help the advance of microbiology, and in more general, experimental ecology.

An Open Learner Model for Trainee Pilots

ERIC Educational Resources Information Center

Gakhal, Inderdip; Bull, Susan

2008-01-01

This paper investigates the potential for simple open learner models for highly motivated, independent learners, using the example of trainee pilots. In particular we consider whether such users access their learner model to help them identify their current knowledge level, areas of difficulty and specific misconceptions, to help them plan their…

The effect of contact angles and capillary dimensions on the burst frequency of super hydrophilic and hydrophilic centrifugal microfluidic platforms, a CFD study.

PubMed

Kazemzadeh, Amin; Ganesan, Poo; Ibrahim, Fatimah; He, Shuisheng; Madou, Marc J

2013-01-01

This paper employs the volume of fluid (VOF) method to numerically investigate the effect of the width, height, and contact angles on burst frequencies of super hydrophilic and hydrophilic capillary valves in centrifugal microfluidic systems. Existing experimental results in the literature have been used to validate the implementation of the numerical method. The performance of capillary valves in the rectangular and the circular microfluidic structures on super hydrophilic centrifugal microfluidic platforms is studied. The numerical results are also compared with the existing theoretical models and the differences are discussed. Our experimental and computed results show a minimum burst frequency occurring at square capillaries and this result is useful for designing and developing more sophisticated networks of capillary valves. It also predicts that in super hydrophilic microfluidics, the fluid leaks consistently from the capillary valve at low pressures which can disrupt the biomedical procedures in centrifugal microfluidic platforms.

Microfluidic devices for cell cultivation and proliferation

PubMed Central

Tehranirokh, Masoomeh; Kouzani, Abbas Z.; Francis, Paul S.; Kanwar, Jagat R.

2013-01-01

Microfluidic technology provides precise, controlled-environment, cost-effective, compact, integrated, and high-throughput microsystems that are promising substitutes for conventional biological laboratory methods. In recent years, microfluidic cell culture devices have been used for applications such as tissue engineering, diagnostics, drug screening, immunology, cancer studies, stem cell proliferation and differentiation, and neurite guidance. Microfluidic technology allows dynamic cell culture in microperfusion systems to deliver continuous nutrient supplies for long term cell culture. It offers many opportunities to mimic the cell-cell and cell-extracellular matrix interactions of tissues by creating gradient concentrations of biochemical signals such as growth factors, chemokines, and hormones. Other applications of cell cultivation in microfluidic systems include high resolution cell patterning on a modified substrate with adhesive patterns and the reconstruction of complicated tissue architectures. In this review, recent advances in microfluidic platforms for cell culturing and proliferation, for both simple monolayer (2D) cell seeding processes and 3D configurations as accurate models of in vivo conditions, are examined. PMID:24273628

The Effect of Contact Angles and Capillary Dimensions on the Burst Frequency of Super Hydrophilic and Hydrophilic Centrifugal Microfluidic Platforms, a CFD Study

PubMed Central

Kazemzadeh, Amin; Ganesan, Poo; Ibrahim, Fatimah; He, Shuisheng; Madou, Marc J.

2013-01-01

This paper employs the volume of fluid (VOF) method to numerically investigate the effect of the width, height, and contact angles on burst frequencies of super hydrophilic and hydrophilic capillary valves in centrifugal microfluidic systems. Existing experimental results in the literature have been used to validate the implementation of the numerical method. The performance of capillary valves in the rectangular and the circular microfluidic structures on super hydrophilic centrifugal microfluidic platforms is studied. The numerical results are also compared with the existing theoretical models and the differences are discussed. Our experimental and computed results show a minimum burst frequency occurring at square capillaries and this result is useful for designing and developing more sophisticated networks of capillary valves. It also predicts that in super hydrophilic microfluidics, the fluid leaks consistently from the capillary valve at low pressures which can disrupt the biomedical procedures in centrifugal microfluidic platforms. PMID:24069169

Microfluidic cell culture systems for drug research.

PubMed

Wu, Min-Hsien; Huang, Song-Bin; Lee, Gwo-Bin

2010-04-21

In pharmaceutical research, an adequate cell-based assay scheme to efficiently screen and to validate potential drug candidates in the initial stage of drug discovery is crucial. In order to better predict the clinical response to drug compounds, a cell culture model that is faithful to in vivo behavior is required. With the recent advances in microfluidic technology, the utilization of a microfluidic-based cell culture has several advantages, making it a promising alternative to the conventional cell culture methods. This review starts with a comprehensive discussion on the general process for drug discovery and development, the role of cell culture in drug research, and the characteristics of the cell culture formats commonly used in current microfluidic-based, cell-culture practices. Due to the significant differences in several physical phenomena between microscale and macroscale devices, microfluidic technology provides unique functionality, which is not previously possible by using traditional techniques. In a subsequent section, the niches for using microfluidic-based cell culture systems for drug research are discussed. Moreover, some critical issues such as cell immobilization, medium pumping or gradient generation in microfluidic-based, cell-culture systems are also reviewed. Finally, some practical applications of microfluidic-based, cell-culture systems in drug research particularly those pertaining to drug toxicity testing and those with a high-throughput capability are highlighted.

The Crisis in Scholarly Communication, Open Access, and Open Data Policies: The Libraries' Perspective

NASA Astrophysics Data System (ADS)

Besara, Rachel

2015-03-01

For years the cost of STEM databases have exceeded the rate of inflation. Libraries have reallocated funds for years to continue to provide support to their scientific communities, but they are reaching a point at many institutions where they are no longer able to provide access to many databases considered standard to support research. A possible or partial alleviation to this problem is the federal open access mandate. However, this shift challenges the current model of publishing and data management in the sciences. This talk will discuss these topics from the perspective of research libraries supporting physics and the STEM disciplines.

Microfluidic Liquid-Liquid Contactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mcculloch, Quinn

2017-07-25

This report describes progress made on the microfluidic contactor. A model was developed to predict its failure, a surrogate chemical system was selected to demonstrate mass transfer, and an all-optical system has been invented and implemented to monitor carryover and flowrates.

Hydrogen peroxide concentration by pervaporation of a ternary liquid solution in microfluidics.

PubMed

Ziemecka, Iwona; Haut, Benoît; Scheid, Benoit

2015-01-21

Pervaporation in a microfluidic device is performed on liquid ternary solutions of hydrogen peroxide-water-methanol in order to concentrate hydrogen peroxide (H2O2) by removing methanol. The quantitative analysis of the pervaporation of solutions with different initial compositions is performed, varying the operating temperature of the microfluidic device. Experimental results together with a mathematical model of the separation process are used to understand the effect of the operating conditions on the microfluidic device efficiency. The parameters influencing significantly the performance of pervaporation in the microfluidic device are determined and the limitations of the process are discussed. For the analysed system, the operating temperature of the chip has to be below the temperature at which H2O2 decomposes. Therefore, the choice of an adequate reduced operating pressure is required, depending on the expected separation efficiency.

Modeling and validation of autoinducer-mediated bacterial gene expression in microfluidic environments

PubMed Central

Austin, Caitlin M.; Stoy, William; Su, Peter; Harber, Marie C.; Bardill, J. Patrick; Hammer, Brian K.; Forest, Craig R.

2014-01-01

Biosensors exploiting communication within genetically engineered bacteria are becoming increasingly important for monitoring environmental changes. Currently, there are a variety of mathematical models for understanding and predicting how genetically engineered bacteria respond to molecular stimuli in these environments, but as sensors have miniaturized towards microfluidics and are subjected to complex time-varying inputs, the shortcomings of these models have become apparent. The effects of microfluidic environments such as low oxygen concentration, increased biofilm encapsulation, diffusion limited molecular distribution, and higher population densities strongly affect rate constants for gene expression not accounted for in previous models. We report a mathematical model that accurately predicts the biological response of the autoinducer N-acyl homoserine lactone-mediated green fluorescent protein expression in reporter bacteria in microfluidic environments by accommodating these rate constants. This generalized mass action model considers a chain of biomolecular events from input autoinducer chemical to fluorescent protein expression through a series of six chemical species. We have validated this model against experimental data from our own apparatus as well as prior published experimental results. Results indicate accurate prediction of dynamics (e.g., 14% peak time error from a pulse input) and with reduced mean-squared error with pulse or step inputs for a range of concentrations (10 μM–30 μM). This model can help advance the design of genetically engineered bacteria sensors and molecular communication devices. PMID:25379076

Rates and equilibrium constants of the ligand-induced conformational transition of an HCN ion channel protein domain determined by DEER spectroscopy.

PubMed

Collauto, Alberto; DeBerg, Hannah A; Kaufmann, Royi; Zagotta, William N; Stoll, Stefan; Goldfarb, Daniella

2017-06-14

Ligand binding can induce significant conformational changes in proteins. The mechanism of this process couples equilibria associated with the ligand binding event and the conformational change. Here we show that by combining the application of W-band double electron-electron resonance (DEER) spectroscopy with microfluidic rapid freeze quench (μRFQ) it is possible to resolve these processes and obtain both equilibrium constants and reaction rates. We studied the conformational transition of the nitroxide labeled, isolated carboxy-terminal cyclic-nucleotide binding domain (CNBD) of the HCN2 ion channel upon binding of the ligand 3',5'-cyclic adenosine monophosphate (cAMP). Using model-based global analysis, the time-resolved data of the μRFQ DEER experiments directly provide fractional populations of the open and closed conformations as a function of time. We modeled the ligand-induced conformational change in the protein using a four-state model: apo/open (AO), apo/closed (AC), bound/open (BO), bound/closed (BC). These species interconvert according to AC + L ⇌ AO + L ⇌ BO ⇌ BC. By analyzing the concentration dependence of the relative contributions of the closed and open conformations at equilibrium, we estimated the equilibrium constants for the two conformational equilibria and the open-state ligand dissociation constant. Analysis of the time-resolved μRFQ DEER data gave estimates for the intrinsic rates of ligand binding and unbinding as well as the rates of the conformational change. This demonstrates that DEER can quantitatively resolve both the thermodynamics and the kinetics of ligand binding and the associated conformational change.

PMMA/PDMS valves and pumps for disposable microfluidics.

PubMed

Zhang, Wenhua; Lin, Shuichao; Wang, Chunming; Hu, Jia; Li, Cong; Zhuang, Zhixia; Zhou, Yongliang; Mathies, Richard A; Yang, Chaoyong James

2009-11-07

Poly(methyl methacrylate) (PMMA) is gaining in popularity in microfluidic devices because of its low cost, excellent optical transparency, attractive mechanical/chemical properties, and simple fabrication procedures. It has been used to fabricate micromixers, PCR reactors, CE and many other microdevices. Here we present the design, fabrication, characterization and application of pneumatic microvalves and micropumps based on PMMA. Valves and pumps are fabricated by sandwiching a PDMS membrane between PMMA fluidic channel and manifold wafers. Valve closing or opening can be controlled by adjusting the pressure in a displacement chamber on the pneumatic layer via a computer regulated solenoid. The valve provides up to 15.4 microL s(-1) at 60 kPa fluid pressure and seals reliably against forward fluid pressure as high as 60 kPa. A PMMA diaphragm pump can be assembled by simply connecting three valves in series. By varying valve volume or opening time, pumping rates ranging from nL to microL per second can be accurately achieved. The PMMA based valves and pumps were further tested in a disposable automatic nucleic acid extraction microchip to extract DNA from human whole blood. The DNA extraction efficiency was about 25% and the 260 nm/280 nm UV absorption ratio for extracted DNA was 1.72. Because of its advantages of inexpensive, facile fabrication, robust and easy integration, the PMMA valve and pump will find their wide application for fluidic manipulation in portable and disposable microfluidic devices.

Stem cell research funding policies and dynamic innovation: a survey of open access and commercialization requirements.

PubMed

Lévesque, Maroussia; Kim, Jihyun Rosel; Isasi, Rosario; Knoppers, Bartha Maria; Plomer, Aurora; Joly, Yann

2014-08-01

This article compares and contrasts the pressures of both open access data sharing and commercialization policies in the context of publicly funded embryonic stem cell research (SCR). First, normative guidelines of international SCR organizations were examined. We then examined SCR funding guidelines and the project evaluation criteria of major funding organizations in the EU, the United Kingdom (UK), Spain, Canada and the United States. Our survey of policies revealed subtle pressures to commercialize research that include: increased funding availability for commercialization opportunities, assistance for obtaining intellectual property rights (IPRs) and legislation mandating commercialization. In lieu of open access models, funders are increasingly opting for limited sharing models or "protected commons" models that make the research available to researchers within the same region or those receiving the same funding. Meanwhile, there still is need for funding agencies to clarify and standardize terms such as "non-profit organizations" and "for-profit research," as more universities are pursuing for-profit or commercial opportunities.

Control of evaporation by geometry in capillary structures. From confined pillar arrays in a gap radial gradient to phyllotaxy-inspired geometry.

PubMed

Chen, Chen; Duru, Paul; Joseph, Pierre; Geoffroy, Sandrine; Prat, Marc

2017-11-08

Evaporation is a key phenomenon in the natural environment and in many technological systems involving capillary structures. Understanding the evaporation front dynamics enables the evaporation rate from microfluidic devices and porous media to be finely controlled. Of particular interest is the ability to control the position of the front through suitable design of the capillary structure. Here, we show how to design model capillary structures in microfluidic devices so as to control the drying kinetics. This is achieved by acting on the spatial organization of the constrictions that influence the invasion of the structure by the gas phase. Two types of control are demonstrated. The first is intended to control the sequence of primary invasions through the pore space, while the second aims to control the secondary liquid structures: films, bridges, etc., that can form in the region of pore space invaded by the gas phase. It is shown how the latter can be obtained from phyllotaxy-inspired geometry. Our study thus opens up a route toward the control of the evaporation kinetics by means of tailored capillary structures.

Vapor and liquid optical monitoring with sculptured Bragg microcavities

NASA Astrophysics Data System (ADS)

Oliva-Ramirez, Manuel; Gil-Rostra, Jorge; López-Santos, Maria Carmen; González-Elipe, Agustín R.; Yubero, Francisco

2017-10-01

Sculptured porous Bragg microcavities (BMs) formed by the successive stacking of columnar SiO2 and TiO2 thin films with a zig-zag columnar microstructure are prepared by glancing angle deposition. These BMs act as wavelength-dependent optical retarders. This optical behavior is attributed to a self-structuration of the stacked layers involving the lateral association of nanocolumns in the direction perpendicular to the main flux of particles during the multilayer film growth, as observed by focused ion beam scanning electron microscopy. The retardance of these optically active BMs can be modulated by dynamic infiltration of their open porosity with vapors, liquids, or solutions with different refractive indices. The tunable birefringence of these nanostructured photonic systems has been successfully simulated with a simple model that assumes that each layer within the BMs stack has uniaxial birefringence. The sculptured BMs have been incorporated as microfluidic chips for optical transduction for label-free vapor and liquid sensing. Several examples of the detection performance of these chips, working either in reflection or transmission configuration, for the optical monitoring of vapor and liquids of different refractive indices and aqueous solutions of glucose flowing through the microfluidic chips are described.

Biologically Inspired Electronic, Photovoltaic and Microfluidic Devices Based on Aqueous Soft Matter

NASA Astrophysics Data System (ADS)

Koo, Hyung Jun

Hydrogels are a water-based soft material where three dimensional networks of hydrophilic polymer retain large amounts of water. We developed hydrogel based devices with new functionalities inspired by materials, structures and processes in nature. The advantages, such as softness, biocompatibility and high ionic conductivity, could enable hydrogels to be novel materials for biomimetic devices operated by ionic current. Moreover, microfluidic patterns are easily embedded in moldable hydrogels and allow for unique convective/diffusive transport mechanism in porous gel to be used for uniform delivery of reagent solution. We first developed and characterized a device with unidirectional ionic current flow across a SiO2/Gel junction, which showed highly efficient rectification of the ionic current by non-linear conductivity of SiO2 films. Addition of polyelectrolytes and salt to the gel layer significantly improved the performance of the new diode device because of the enhanced gel conductance. A soft matter based diode composed of hydrogel and liquid metal (eutectic gallium indium, EGaIn) was also presented. The ability to control the thickness, and thus resistivity, of an insulating oxide skin on the metal enables the current rectification. The effect of ionic conductivity and pH on the formation of the insulating oxide was investigated in a simple model system with liquid metal/electrolyte solution or hydrogel/Pt interfaces. Finally, we present a diode composed entirely of soft materials by replacing the platinum electrode with a second liquid metal electrode. A new type of hydrogel-based photovoltaic systems (HGPVs) was constructed. Two photosensitive ionized molecules embedded in aqueous gel served as photoactive species. The HGPVs showed performance comparable with or higher than those of some other biomimetic or ionic photovoltaic systems reported recently. We suggest a provisional mechanism of the device operation, based on a synergetic effect of the two dye molecules. To reduce the fabrication cost without efficiency loss, we found an inexpensive replacement of the expensive Pt counter-electrode with copper coated with carbon materials. Biologically derived photoactive molecules, such as Chlorophyll and Photosystem II, were successfully operated in the aqueous gel of such HGPVs. As a proof of demonstration of biomimetic structures, a light driven biomimetic reactor was developed by using hydrogel media with embedded photocatalytic TiO2 nanoparticles. Uniform supply of the reactants and extraction of the products was accomplished via a microfluidic channel network, broadly similar to the vein structure of live leaves. The dyes were transported in the gel between the microchannels and degraded by photocatalytic oxidation by the illuminated TiO2 particles. Quantitative analysis of the photocatalytic degradation rate of the injected dyes revealed that the microvascular reactor has high quantum efficiency per catalyst mass. Numerical modeling was performed to explore how a soluble reagent could be supplied rapidly and efficiently through microfluidic channel networks embedded in hydrogels. The computational model takes into account the fluid transport in porous media and the solute convection and diffusion, to simulate the solute distribution and outflux with time in microfluidic hydrogel media. The effect of the channel dimensions and shapes on mass transport rapidity and efficiency was quantitatively evaluated. Experimental data proved the validity of the time dependent concentration profile calculated by the simulation. Lastly, a microfluidic hydrogel solar cell with biomimetic regeneration functionality was demonstrated as a result of the above experimental and modeling studies. A new concept of open and replenishable photovoltaics was constructed on the basis of dye-sensitized solar cells. Photovoltaic reagents, dyes and redox electrolytes, were uniformly delivered via microfluidic networks embedded in a hydrogel, resulting in increase of photocurrent generation. The regeneration process was established, based on the pH dependence of adsorption/desorption kinetics of the dye molecules on a TiO2 photoanode. Complete and reliable recovery of the photocurrent after an accelerated photodegradation in the biomimetic photovoltaics was demonstrated.

Open access and preservation of data on the coupled geosphere-biosphere system: the case of the H2020 Project ECOPOTENTIAL

NASA Astrophysics Data System (ADS)

Provenzale, Antonello; Nativi, Stefano

2016-04-01

The H2020 ECOPOTENTIAL Project addresses the entire chain of ecosystem-related services, by focusing on the interaction between the biotic and abiotic components of ecosystems (geosphere-biosphere interactions), developing ecosystem data services with special emphasis on Copernicus services, implementing model output services to distribute the results of the modelling activities, and estimating current and future ecosystem services and benefits combining ecosystem functions (supply) with beneficiaries needs (demand). In ECOPOTENTIAL all data, model results and acquired knowledge will be made available on common and open platforms, coherent with the Global Earth Observation System of Systems (GEOSS) data sharing principles and fully interoperable with the GEOSS Common Infrastructure (GCI). ECOPOTENTIAL will be conducted in the context of the implementation of the Copernicus EO Component and in synergy with the ESA Climate Change Initiative. The project activities will contribute to Copernicus and non-Copernicus contexts for ecosystems, and will create an Ecosystem Data Service for Copernicus (ECOPERNICUS), a new open-access, smart and user-friendly geospatial data/products retrieval portal and web coverage service using a dedicated online server. ECOPOTENTIAL will make data, scientific results, models and information accessible and available through a cloud-based open platform implementing virtual laboratories. The platform will be a major contribution to the GEOSS Common Infrastructure, reinforcing the GEOSS Data-CORE. By the end of the project, new prototype products and ecosystem services, based on improved access (notably via GEOSS) and long-term storage of ecosystem EO data and information in existing PAs, will be realized. In this contribution, we discuss the approach followed in the project for Open Data access and use. ECOPOTENTIAL introduced a set of architecture and interoperability principles to facilitate data (and the associated software) discovery, access, (re-)use, and preservation. According to these principles, ECOPOTENTIAL worked out a Data Management Plan that describes how the different data types (generated and/or collected by the project) are going to be managed in the project; in particular: (1) What standards will be used for these data discoverability, accessibility and (re-)use; (2) How these data will be exploited and/or shared/made accessible for verification and reuse; if data cannot be made available, the reasons will be fully explained; and (3) How these data will be curated and preserved, even after the project duration.

In Vitro Microfluidic Models for Neurodegenerative Disorders.

PubMed

Osaki, Tatsuya; Shin, Yoojin; Sivathanu, Vivek; Campisi, Marco; Kamm, Roger D

2018-01-01

Microfluidic devices enable novel means of emulating neurodegenerative disease pathophysiology in vitro. These organ-on-a-chip systems can potentially reduce animal testing and substitute (or augment) simple 2D culture systems. Reconstituting critical features of neurodegenerative diseases in a biomimetic system using microfluidics can thereby accelerate drug discovery and improve our understanding of the mechanisms of several currently incurable diseases. This review describes latest advances in modeling neurodegenerative diseases in the central nervous system and the peripheral nervous system. First, this study summarizes fundamental advantages of microfluidic devices in the creation of compartmentalized cell culture microenvironments for the co-culture of neurons, glial cells, endothelial cells, and skeletal muscle cells and in their recapitulation of spatiotemporal chemical gradients and mechanical microenvironments. Then, this reviews neurodegenerative-disease-on-a-chip models focusing on Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Finally, this study discusses about current drawbacks of these models and strategies that may overcome them. These organ-on-chip technologies can be useful to be the first line of testing line in drug development and toxicology studies, which can contribute significantly to minimize the phase of animal testing steps. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microfluidics: a groundbreaking technology for PET tracer production?

PubMed

Rensch, Christian; Jackson, Alexander; Lindner, Simon; Salvamoser, Ruben; Samper, Victor; Riese, Stefan; Bartenstein, Peter; Wängler, Carmen; Wängler, Björn

2013-07-05

Application of microfluidics to Positron Emission Tomography (PET) tracer synthesis has attracted increasing interest within the last decade. The technical advantages of microfluidics, in particular the high surface to volume ratio and resulting fast thermal heating and cooling rates of reagents can lead to reduced reaction times, increased synthesis yields and reduced by-products. In addition automated reaction optimization, reduced consumption of expensive reagents and a path towards a reduced system footprint have been successfully demonstrated. The processing of radioactivity levels required for routine production, use of microfluidic-produced PET tracer doses in preclinical and clinical imaging as well as feasibility studies on autoradiolytic decomposition have all given promising results. However, the number of microfluidic synthesizers utilized for commercial routine production of PET tracers is very limited. This study reviews the state of the art in microfluidic PET tracer synthesis, highlighting critical design aspects, strengths, weaknesses and presenting several characteristics of the diverse PET market space which are thought to have a significant impact on research, development and engineering of microfluidic devices in this field. Furthermore, the topics of batch- and single-dose production, cyclotron to quality control integration as well as centralized versus de-centralized market distribution models are addressed.

Collective oscillations and coupled modes in confined microfluidic droplet arrays

NASA Astrophysics Data System (ADS)

Schiller, Ulf D.; Fleury, Jean-Baptiste; Seemann, Ralf; Gompper, Gerhard

Microfluidic droplets have a wide range of applications ranging from analytic assays in cellular biology to controlled mixing in chemical engineering. Ensembles of microfluidic droplets are interesting model systems for non-equilibrium many-body phenomena. When flowing in a microchannel, trains of droplets can form microfluidic crystals whose dynamics are governed by long-range hydrodynamic interactions and boundary effects. In this contribution, excitation mechanisms for collective waves in dense and confined microfluidic droplet arrays are investigated by experiments and computer simulations. We demonstrate that distinct modes can be excited by creating specific `defect' patterns in flowing droplet trains. While longitudinal modes exhibit a short-lived cascade of pairs of laterally displacing droplets, transversely excited modes form propagating waves that behave like microfluidic phonons. We show that the confinement induces a coupling between longitudinal and transverse modes. We also investigate the life time of the collective oscillations and discuss possible mechanisms for the onset of instabilities. Our results demonstrate that microfluidic phonons can exhibit effects beyond the linear theory, which can be studied particularly well in dense and confined systems. This work was supported by Deutsche Forschungsgemeinschaft under Grant No. SE 1118/4.

Toward establishing model organisms for marine protists: Successful transfection protocols for Parabodo caudatus (Kinetoplastida: Excavata).

PubMed

Gomaa, Fatma; Garcia, Paulo A; Delaney, Jennifer; Girguis, Peter R; Buie, Cullen R; Edgcomb, Virginia P

2017-09-01

We developed protocols for, and demonstrated successful transfection of, the free-living kinetoplastid flagellate Parabodo caudatus with three plasmids carrying a fluorescence reporter gene (pEF-GFP with the EF1 alpha promoter, pUB-GFP with Ubiquitin C promoter, and pEYFP-Mitotrap with CMV promoter). We evaluated three electroporation approaches: (1) a square-wave electroporator designed for eukaryotes, (2) a novel microfluidic transfection system employing hydrodynamically-controlled electric field waveforms, and (3) a traditional exponential decay electroporator. We found the microfluidic device provides a simple and efficient platform to quickly test a wide range of electric field parameters to find the optimal set of conditions for electroporation of target species. It also allows for processing large sample volumes (>10 ml) within minutes, increasing throughput 100 times over cuvettes. Fluorescence signal from the reporter gene was detected a few hours after transfection and persisted for 3 days in cells transfected by pEF-GFP and pUB-GFP plasmids and for at least 5 days post-transfection for cells transfected with pEYFP-Mitotrap. Expression of the reporter genes (GFP and YFP) was also confirmed using reverse transcription-PCR (RT-PCR). This work opens the door for further efforts with this taxon and close relatives toward establishing model systems for genome editing. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Comparative Kinetic Analysis of Closed-Ended and Open-Ended Porous Sensors

NASA Astrophysics Data System (ADS)

Zhao, Yiliang; Gaur, Girija; Mernaugh, Raymond L.; Laibinis, Paul E.; Weiss, Sharon M.

2016-09-01

Efficient mass transport through porous networks is essential for achieving rapid response times in sensing applications utilizing porous materials. In this work, we show that open-ended porous membranes can overcome diffusion challenges experienced by closed-ended porous materials in a microfluidic environment. A theoretical model including both transport and reaction kinetics is employed to study the influence of flow velocity, bulk analyte concentration, analyte diffusivity, and adsorption rate on the performance of open-ended and closed-ended porous sensors integrated with flow cells. The analysis shows that open-ended pores enable analyte flow through the pores and greatly reduce the response time and analyte consumption for detecting large molecules with slow diffusivities compared with closed-ended pores for which analytes largely flow over the pores. Experimental confirmation of the results was carried out with open- and closed-ended porous silicon (PSi) microcavities fabricated in flow-through and flow-over sensor configurations, respectively. The adsorption behavior of small analytes onto the inner surfaces of closed-ended and open-ended PSi membrane microcavities was similar. However, for large analytes, PSi membranes in a flow-through scheme showed significant improvement in response times due to more efficient convective transport of analytes. The experimental results and theoretical analysis provide quantitative estimates of the benefits offered by open-ended porous membranes for different analyte systems.

Open access to scientific articles: a review of benefits and challenges.

PubMed

Björk, Bo-Christer

2017-03-01

The Internet has fundamentally changed the publishing of scholarly peer reviewed journals, and the way readers find and access articles. Digital access is nowadays the norm, in particular for researchers. The Internet has enabled a totally new business model, Open Access (OA), in which an article is openly available in full text for anyone with Internet access. This article reviews the different options to achieve this, whether by journals changing their revenue structures from subscription to publishing charges, or authors utilizing a number of options for posting OA versions of article manuscripts in repositories. It also discusses the regrettable emergence of "predatory" publishers, who spam academics, and make money by promising them rapid publication with only the semblance of peer review. The situation is further discussed from the viewpoints of different stakeholders, including academics as authors and readers, practicing physicians and the general public.

Getting started with Open-Hardware: Development and Control of Microfluidic Devices

PubMed Central

da Costa, Eric Tavares; Mora, Maria F.; Willis, Peter A.; do Lago, Claudimir L.; Jiao, Hong; Garcia, Carlos D.

2014-01-01

Understanding basic concepts of electronics and computer programming allows researchers to get the most out of the equipment found in their laboratories. Although a number of platforms have been specifically designed for the general public and are supported by a vast array of on-line tutorials, this subject is not normally included in university chemistry curricula. Aiming to provide the basic concepts of hardware and software, this article is focused on the design and use of a simple module to control a series of PDMS-based valves. The module is based on a low-cost microprocessor (Teensy) and open-source software (Arduino). The microvalves were fabricated using thin sheets of PDMS and patterned using CO2 laser engraving, providing a simple and efficient way to fabricate devices without the traditional photolithographic process or facilities. Synchronization of valve control enabled the development of two simple devices to perform injection (1.6 ± 0.4 μL/stroke) and mixing of different solutions. Furthermore, a practical demonstration of the utility of this system for microscale chemical sample handling and analysis was achieved performing an on-chip acid-base titration, followed by conductivity detection with an open-source low-cost detection system. Overall, the system provided a very reproducible (98%) platform to perform fluid delivery at the microfluidic scale. PMID:24823494

From functional structure to packaging: full-printing fabrication of a microfluidic chip.

PubMed

Zheng, Fengyi; Pu, Zhihua; He, Enqi; Huang, Jiasheng; Yu, Bocheng; Li, Dachao; Li, Zhihong

2018-05-24

This paper presents a concept of a full-printing methodology aiming at convenient and fast fabrication of microfluidic devices. For the first time, we achieved a microfluidic biochemical sensor with all functional structures fabricated by inkjet printing, including electrodes, immobilized enzymes, microfluidic components and packaging. With the cost-effective and rapid process, this method provides the possibility of quick model validation of a novel lab-on-chip system. In this study, a three-electrode electrochemical system was integrated successfully with glucose oxidase immobilization gel and sealed in an ice channel, forming a disposable microfluidic sensor for glucose detection. This fully-printed chip was characterized and showed good sensitivity and a linear section at a low-level concentration of glucose (0-10 mM). With the aid of automatic equipment, the fully-printed sensor can be massively produced with low cost.

Stochastic Model of Clogging in a Microfluidic Cell Sorter

NASA Astrophysics Data System (ADS)

Fai, Thomas; Rycroft, Chris

2016-11-01

Microfluidic devices for sorting cells by deformability show promise for various medical purposes, e.g. detecting sickle cell anemia and circulating tumor cells. One class of such devices consists of a two-dimensional array of narrow channels, each column containing several identical channels in parallel. Cells are driven through the device by an applied pressure or flow rate. Such devices allows for many cells to be sorted simultaneously, but cells eventually clog individual channels and change the device properties in an unpredictable manner. In this talk, we propose a stochastic model for the failure of such microfluidic devices by clogging and present preliminary theoretical and computational results. The model can be recast as an ODE that exhibits finite time blow-up under certain conditions. The failure time distribution is investigated analytically in certain limiting cases, and more realistic versions of the model are solved by computer simulation.

3D capillary stop valves for versatile patterning inside microfluidic chips.

PubMed

Papadimitriou, V A; Segerink, L I; van den Berg, A; Eijkel, J C T

2018-02-13

The patterning of antibodies in microfluidics chips is always a delicate process that is usually done in an open chip before bonding. Typical bonding techniques such as plasma treatment can harm the antibodies with as result that they are removed from our fabrication toolbox. Here we propose a method, based on capillary phenomena using 3D capillary valves, that autonomously and conveniently allows us to pattern liquids inside closed chips. We theoretically analyse the system and demonstrate how our analysis can be used as a design tool for various applications. Chips patterned with the method were used for simple immunodetection of a cardiac biomarker which demonstrates its suitability for antibody patterning. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Spintronic microfluidic platform for biomedical and environmental applications

NASA Astrophysics Data System (ADS)

Cardoso, F. A.; Martins, V. C.; Fonseca, L. P.; Germano, J.; Sousa, L. A.; Piedade, M. S.; Freitas, P. P.

2010-09-01

Faster, more sensitive and easy to operate biosensing devices still are a need at important areas such as biomedical diagnostics, food control and environmental monitoring. Recently, spintronic-devices have emerged as a promising alternative to the existent technologies [1-3]. A number of advantages, namely high sensitivity, easy integration, miniaturization, scalability, robustness and low cost make these devices potentially capable of responding to the existent technological need. In parallel, the field of microfluidics has shown great advances [4]. Microfluidic systems allow the analysis of small sample volumes (from micro- down to pico-liters), often by automate sample processing with the ability to integrate several steps into a single device (analyte amplification, concentration, separation and/or labeling), all in a reduced assay time (minutes to hours) and affordable cost. The merging of these two technologies, magnetoresistive biochips and microfluidics, will enable the development of highly competitive devices. This work reports the integration of a magnetoresistive biochip with a microfluidic system inside a portable and autonomous electronic platform aiming for a fully integrated device. A microfluidic structure fabricated in polydimethylsiloxane with dimensions of W: 0.5mm, H: 0.1mm, L: 10mm, associated to a mechanical system to align and seal the channel by pressure is presented (Fig. 1) [5]. The goal is to perform sample loading and transportation over the chip and simultaneously control the stringency and uniformity of the wash-out process. The biochip output is acquired by an electronic microsystem incorporating the circuitry to control, address and read-out the 30 spin-valve sensors sequentially (Fig. 1) [2]. This platform is being applied to the detection of water-borne microbial pathogens (e.g. Salmonella and Escherichia coli) and genetic diseases diagnosis (e.g. cystic fibrosis) through DNA hybridization assays. Open chamber measurements were performed as described elsewhere [2]. Briefly, a 20 μl sample droplet is manually dispensed over the chip, limited by a polymeric frame. When using the microfluidic system for sample loading, a known volume of sample is introduced into the fluidic system through the help of a syringe pump at a controlled velocity.

Globalization, Open Access Publishing, and the Disappearance of Print: Threat or Opportunity?

NASA Astrophysics Data System (ADS)

Blom, J. J.

Academic publishing is changing rapidly as a result of mutually dependent developments. Electronic publishing was born through the emergence of the Internet. The Internet has accelerated globalization, which in turn has enhanced the consolidation of commercial publishing houses and the collaboration between libraries. Old business models are being replaced by new business models, such as open access publishing. The familiar print format is disappearing for journals and perhaps for books. This chapter presents an overview of these developments and addresses potential threats and opportunities to the parties involved in publishing.

Acoustic Streaming and Microparticle Enrichment within a Microliter Droplet Using a Lamb-Wave Resonator Array

NASA Astrophysics Data System (ADS)

Zhang, Hongxiang; Tang, Zifan; Wang, Zhan; Pan, Shuting; Han, Ziyu; Sun, Chongling; Zhang, Menglun; Duan, Xuexin; Pang, Wei

2018-06-01

We report the nonlinear acoustic streaming effect and the fast manipulation of microparticles by microelectromechanical Lamb-wave resonators in a microliter droplet. The device, consisting of four Lamb-wave resonators on a silicon die, generates cylindrical traveling waves in a liquid and efficiently drives nine horizontal vortices within a 1 -μ l droplet; the performance of the device coincides with the numerical model prediction. Experimentally, the particles are enriched at the stagnation center of the main vortex on the free surface of the droplet in open space without microfluidic channels. In addition, the trajectories of the particles in the droplet can be controlled by the excitation power.

Nanobubbles in confined solution: Generation, contact angle, and stability.

PubMed

Wei, Jiachen; Zhang, Xianren; Song, Fan; Shao, Yingfeng

2018-02-14

The formation of gas bubbles presents a frequent challenge to microfluidic operations, for which fluids are geometrically confined to a microscale space. Here, to understand the mechanism of nucleating gas bubbles in microfluidic devices, we investigate the formation and stability of nanobubbles in confined solutions. Our molecular dynamics simulations show that while pinning of the contact line is a prerequisite for the stability of surface nanobubbles in open systems that can exchange gas with surrounding environment, in confined solutions, stable nanobubbles can exist even without pinning. In supersaturated condition, stable bubbles can be found in confined solutions with acute or obtuse contact angle, depending on the substrate hydrophobicity. We also demonstrate that when open to the bulk solution, the stable nanobubbles in closed systems would become unstable unless both supersaturation and pinning of the contact line are satisfied. Our results not only shed light on the design of novel heterogeneous surfaces for generating nanobubbles in confined space with controllable shape and stability but also address the crucial effect of gas exchange with the surroundings in determining the stability of nanobubbles.

Nanobubbles in confined solution: Generation, contact angle, and stability

NASA Astrophysics Data System (ADS)

Wei, Jiachen; Zhang, Xianren; Song, Fan; Shao, Yingfeng

2018-02-01

The formation of gas bubbles presents a frequent challenge to microfluidic operations, for which fluids are geometrically confined to a microscale space. Here, to understand the mechanism of nucleating gas bubbles in microfluidic devices, we investigate the formation and stability of nanobubbles in confined solutions. Our molecular dynamics simulations show that while pinning of the contact line is a prerequisite for the stability of surface nanobubbles in open systems that can exchange gas with surrounding environment, in confined solutions, stable nanobubbles can exist even without pinning. In supersaturated condition, stable bubbles can be found in confined solutions with acute or obtuse contact angle, depending on the substrate hydrophobicity. We also demonstrate that when open to the bulk solution, the stable nanobubbles in closed systems would become unstable unless both supersaturation and pinning of the contact line are satisfied. Our results not only shed light on the design of novel heterogeneous surfaces for generating nanobubbles in confined space with controllable shape and stability but also address the crucial effect of gas exchange with the surroundings in determining the stability of nanobubbles.

Drop mass transfer in a microfluidic chip compared to a centrifugal contactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nemer, Martin B.; Roberts, Christine C.; Hughes, Lindsey G.

2014-06-13

A model system was developed for enabling a multiscale understanding of centrifugal-contactor liquid–liquid extraction.The system consisted of Nd(III) + xylenol orange in the aqueous phase buffered to pH =5.5 by KHP, and dodecane + thenoyltrifluroroacetone (HTTA) + tributyphosphate (TBP) in the organic phase. Diffusion constants were measured for neodymium in both the organic and aqueous phases, and the Nd(III) partition coefficients were measured at various HTTA and TBP concentrations. A microfluidic channel was used as a high-shear model environment to observe mass-transfer on a droplet scale with xylenol orange as the aqueous-phase metal indicator; mass-transfer rates were measured quantitatively inmore » both diffusion and reaction limited regimes on the droplet scale. Lastly, the microfluidic results were comparable to observations made for the same system in a laboratory scale liquid–liquid centrifugal contactor, indicating that single drop microfluidic experiments can provide information on mass transfer in complicated flows and geometries.« less

Relaxation of microparticles exposed to hydrodynamic forces in microfluidic conduits.

PubMed

Janča, Josef; Halabalová, Věra; Polášek, Vladimír; Vašina, Martin; Menshikova, Anastasia Yu

2011-02-01

The behavior of microparticles exposed to gravitational and lift forces and to the velocity gradient in flow velocity profile formed in microfluidic conduits is studied from the viewpoint of the transient period (the relaxation) between the moment at which a particle starts to be transported by the hydrodynamic flow and the time at which it reaches an equilibrium position, characterized by a balance of all active forces. The theoretical model allowing the calculation of the relaxation time is proposed. The numerical calculus based on the proposed model is compared with the experimental data obtained under different experimental conditions, namely, for different lengths of microfluidic channels, different average linear velocities of the carrier liquid, and different sizes and densities of the particles used in the study. The results are important for the optimization of microfluidic separation units such as microthermal field-flow fractionation channels in which the separation or manipulation of the microparticles of various origin, synthetic, natural, biological, etc., is performed under similar experimental conditions but by applying an additional thermodynamic force.

Finite element modeling simulation-assisted design of integrated microfluidic chips for heavy metal ion stripping analysis

NASA Astrophysics Data System (ADS)

Hong, Ying; Zou, Jianhua; Ge, Gang; Xiao, Wanyue; Gao, Ling; Shao, Jinjun; Dong, Xiaochen

2017-10-01

In this article, a transparent integrated microfluidic device composed of a 3D-printed thin-layer flow cell (3D-PTLFC) and an S-shaped screen-printed electrode (SPE) has been designed and fabricated for heavy metal ion stripping analysis. A finite element modeling (FEM) simulation is employed to optimize the shape of the electrode, the direction of the inlet pipeline, the thin-layer channel height and the sample flow rate to enhance the electron-enrichment efficiency for stripping analysis. The results demonstrate that the S-shaped SPE configuration matches the channel in 3D-PTLFC perfectly for the anodic stripping behavior of the heavy metal ions. Under optimized conditions, a wide linear range of 1-80 µg l-1 is achieved for Pb2+ detection with a limit of 0.3 µg l-1 for the microfluidic device. Thus, the obtained integrated microfluidic device proves to be a promising approach for heavy metal ions stripping analysis with low cost and high performance.

Chemical Thermodynamics of Aqueous Atmospheric Aerosols: Modeling and Microfluidic Measurements

NASA Astrophysics Data System (ADS)

Nandy, L.; Dutcher, C. S.

2017-12-01

Accurate predictions of gas-liquid-solid equilibrium phase partitioning of atmospheric aerosols by thermodynamic modeling and measurements is critical for determining particle composition and internal structure at conditions relevant to the atmosphere. Organic acids that originate from biomass burning, and direct biogenic emission make up a significant fraction of the organic mass in atmospheric aerosol particles. In addition, inorganic compounds like ammonium sulfate and sea salt also exist in atmospheric aerosols, that results in a mixture of single, double or triple charged ions, and non-dissociated and partially dissociated organic acids. Statistical mechanics based on a multilayer adsorption isotherm model can be applied to these complex aqueous environments for predictions of thermodynamic properties. In this work, thermodynamic analytic predictive models are developed for multicomponent aqueous solutions (consisting of partially dissociating organic and inorganic acids, fully dissociating symmetric and asymmetric electrolytes, and neutral organic compounds) over the entire relative humidity range, that represent a significant advancement towards a fully predictive model. The model is also developed at varied temperatures for electrolytes and organic compounds the data for which are available at different temperatures. In addition to the modeling approach, water loss of multicomponent aerosol particles is measured by microfluidic experiments to parameterize and validate the model. In the experimental microfluidic measurements, atmospheric aerosol droplet chemical mimics (organic acids and secondary organic aerosol (SOA) samples) are generated in microfluidic channels and stored and imaged in passive traps until dehydration to study the influence of relative humidity and water loss on phase behavior.

Assembly of multiple cell gradients directed by three-dimensional microfluidic channels.

PubMed

Li, Yiwei; Feng, Xiaojun; Wang, Yachao; Du, Wei; Chen, Peng; Liu, Chao; Liu, Bi-Feng

2015-08-07

Active control over the cell gradient is essential for understanding biological systems and the reconstitution of the functionality of many types of tissues, particularly for organ-on-a-chip. Here, we propose a three-dimensional (3D) microfluidic strategy for generating controllable cell gradients. In this approach, a homogeneous cell suspension is loaded into a 3D stair-shaped PDMS microchannel to generate a cell gradient within 10 min by sedimentation. We demonstrate that cell gradients of various profiles (exponential and piecewise linear) can be achieved by precisely controlling the height of each layer during the fabrication. With sequential seeding, we further demonstrate the generation of two overlapping cell gradients on the same glass substrate with pre-defined designs. The cell gradient-based QD cytotoxicity assay also demonstrated that cell behaviors and resistances were regulated by the changes in cell density. These results reveal that the proposed 3D microfluidic strategy provides a simple and versatile means for establishing controllable gradients in cell density, opening up a new avenue for reconstructing functional tissues.

Wetting-induced formation of controllable monodisperse multiple emulsions in microfluidics.

PubMed

Deng, Nan-Nan; Wang, Wei; Ju, Xiao-Jie; Xie, Rui; Weitz, David A; Chu, Liang-Yin

2013-10-21

Multiple emulsions, which are widely applied in a myriad of fields because of their unique ability to encapsulate and protect active ingredients, are typically produced by sequential drop-formations and drop-encapsulations using shear-induced emulsification. Here we report a qualitatively novel method of creating highly controlled multiple emulsions from lower-order emulsions. By carefully controlling the interfacial energies, we adjust the spreading coefficients between different phases to cause drops of one fluid to completely engulf other drops of immiscible fluids; as a result multiple emulsions are directly formed by simply putting preformed lower-order emulsion drops together. Our approach has highly controllable flexibility. We demonstrate this in preparation of both double and triple emulsions with a controlled number of inner drops and precisely adjusted shell thicknesses including ultra-thin shells. Moreover, this controllable drop-engulfing-drop approach has a high potential in further investigations and applications of microfluidics. Importantly, this innovative approach opens a window to exploit new phenomena occurring in fluids at the microscale level, which is of great significance for developing novel microfluidics.

A review on optical actuators for microfluidic systems

NASA Astrophysics Data System (ADS)

Yang, Tie; Chen, Yue; Minzioni, Paolo

2017-12-01

During the last few decades microfluidic systems have become more and more popular and their relevance in different fields is continually growing. In fact, the use of microchannels allows a significant reduction of the required sample-volume and opens the way to a completely new set of possible investigations, including the study of the properties of cells, the development of new cells’ separation techniques and the analysis of single-cell proteins. One of the main differences between microscopic and macroscopic systems is obviously dictated by the need for suitable actuation mechanisms, which should allow precise control of microscopic fluid volumes and of micro-samples inside the fluid. Even if both syringe-pump and pneumatic-pump technologies significantly evolved and they currently enable sub-μL samples control, completely new approaches were recently developed for the manipulation of samples inside the microchannel. This review is dedicated to describing different kinds of optical actuators that can be applied in microfluidic systems for sample manipulation as well as for pumping. The basic principles underlying the optical actuation mechanisms will be described first, and then several experimental demonstrations will be reviewed and compared.

Capillarics: pre-programmed, self-powered microfluidic circuits built from capillary elements.

PubMed

Safavieh, Roozbeh; Juncker, David

2013-11-07

Microfluidic capillary systems employ surface tension effects to manipulate liquids, and are thus self-powered and self-regulated as liquid handling is structurally and chemically encoded in microscale conduits. However, capillary systems have been limited to perform simple fluidic operations. Here, we introduce complex capillary flow circuits that encode sequential flow of multiple liquids with distinct flow rates and flow reversal. We first introduce two novel microfluidic capillary elements including (i) retention burst valves and (ii) robust low aspect ratio trigger valves. These elements are combined with flow resistors, capillary retention valves, capillary pumps, and open and closed reservoirs to build a capillary circuit that, following sample addition, autonomously delivers a defined sequence of multiple chemicals according to a preprogrammed and predetermined flow rate and time. Such a circuit was used to measure the concentration of C-reactive protein. This work illustrates that as in electronics, complex capillary circuits may be built by combining simple capillary elements. We define such circuits as "capillarics", and introduce symbolic representations. We believe that more complex circuits will become possible by expanding the library of building elements and formulating abstract design rules.

Slopes To Prevent Trapping of Bubbles in Microfluidic Channels

NASA Technical Reports Server (NTRS)

Greer, Harold E.; Lee, Michael C.; Smith, J. Anthony; Willis, Peter A.

2010-01-01

The idea of designing a microfluidic channel to slope upward along the direction of flow of the liquid in the channel has been conceived to help prevent trapping of gas bubbles in the channel. In the original application that gave rise to this idea, the microfluidic channels are parts of micro-capillary electrophoresis (microCE) devices undergoing development for use on Mars in detecting compounds indicative of life. It is necessary to prevent trapping of gas bubbles in these devices because uninterrupted liquid pathways are essential for sustaining the electrical conduction and flows that are essential for CE. The idea is also applicable to microfluidic devices that may be developed for similar terrestrial microCE biotechnological applications or other terrestrial applications in which trapping of bubbles in microfluidic channels cannot be tolerated. A typical microCE device in the original application includes, among other things, multiple layers of borosilicate float glass wafers. Microfluidic channels are formed in the wafers, typically by use of wet chemical etching. The figure presents a simplified cross section of part of such a device in which the CE channel is formed in the lowermost wafer (denoted the channel wafer) and, according to the present innovation, slopes upward into a via hole in another wafer (denoted the manifold wafer) lying immediately above the channel wafer. Another feature of the present innovation is that the via hole in the manifold wafer is made to taper to a wider opening at the top to further reduce the tendency to trap bubbles. At the time of reporting the information for this article, an effort to identify an optimum technique for forming the slope and the taper was in progress. Of the techniques considered thus far, the one considered to be most promising is precision milling by use of femtosecond laser pulses. Other similar techniques that may work equally well are precision milling using a focused ion beam, or a small diamond-tipped drill bit.

A microfluidic approach for hemoglobin detection in whole blood

NASA Astrophysics Data System (ADS)

Taparia, Nikita; Platten, Kimsey C.; Anderson, Kristin B.; Sniadecki, Nathan J.

2017-10-01

Diagnosis of anemia relies on the detection of hemoglobin levels in a blood sample. Conventional blood analyzers are not readily available in most low-resource regions where anemia is prevalent, so detection methods that are low-cost and point-of-care are needed. Here, we present a microfluidic approach to measure hemoglobin concentration in a sample of whole blood. Unlike conventional approaches, our microfluidic approach does not require hemolysis. We detect the level of hemoglobin in a blood sample optically by illuminating the blood in a microfluidic channel at a peak wavelength of 540 nm and measuring its absorbance using a CMOS sensor coupled with a lens to magnify the image onto the detector. We compare measurements in microchannels with channel heights of 50 and 115 μm and found the channel with the 50 μm height provided a better range of detection. Since we use whole blood and not lysed blood, we fit our data to an absorption model that includes optical scattering in order to obtain a calibration curve for our system. Based on this calibration curve and data collected, we can measure hemoglobin concentration within 1 g/dL for severe cases of anemia. In addition, we measured optical density for blood flowing at a shear rate of 500 s-1 and observed it did not affect the nonlinear model. With this method, we provide an approach that uses microfluidic detection of hemoglobin levels that can be integrated with other microfluidic approaches for blood analysis.

Creating Sub-50 Nm Nanofluidic Junctions in PDMS Microfluidic Chip via Self-Assembly Process of Colloidal Particles

PubMed Central

Wei, Xi; Syed, Abeer; Mao, Pan; Han, Jongyoon; Song, Yong-Ak

2016-01-01

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. PMID:27023724

Improving the performance of lactate/oxygen biofuel cells using a microfluidic design

NASA Astrophysics Data System (ADS)

Escalona-Villalpando, Ricardo A.; Reid, Russell C.; Milton, Ross D.; Arriaga, L. G.; Minteer, Shelley D.; Ledesma-García, Janet

2017-02-01

Lactate/O2 biofuel cells (BFC) can have high theoretical energy densities due to high solubility and high fuel energy density; however, they are rarely studied in comparison to glucose BFCs. In this paper, lactate oxidase (LOx) was coupled with a ferrocene-based redox polymer (dimethylferrocene-modified linear polyethylenimine, FcMe2-LPEI) as the bioanode and laccase (Lc) connected to pyrene-anthracene modified carbon nanotubes (PyrAn-MWCNT) to facilitate the direct electron transfer (DET) at the biocathode. Both electrodes were evaluated in two BFC configurations using different concentrations of lactate, in the range found in sweat (0-40 mM). A single compartment BFC evaluated at pH 5.6 provided an open circuit potential (OCP) of 0.68 V with a power density of 61.2 μWcm-2. On the other hand, a microfluidic BFC operating under the same conditions resulted in an OCP of 0.67 V, although an increase in the power density, increasing to 305 μW cm-2, was observed. Upon changing the pH to 7.4 in only the anolyte, its performance was further increased to 0.73 V and 404 μW cm-2, respectively. This work reports the first microfluidic lactate/oxygen enzymatic BFC and shows the importance of microfluidic flow in high performing BFCs where lactate is utilized as the fuel and O2 is the final electron acceptor.

Microfluidics—from fundamental research to industrial applications

NASA Astrophysics Data System (ADS)

Köster, Sarah

2013-03-01

The advance of microfluidics started in the early 1980s. At the time, researchers realized that many processes and reactions in chemistry and biology, which typically take place on small length scales, can be defined, controlled and understood much better when using tools on equally small length scales. Reactions and reaction kinetics rely on (gradual) concentration differences and microfluidics provides the unique possibility to establish exactly such gradients of solutes, ion concentrations, pH value and so on. Nowadays the variety of specific microfluidic methods is large. In principle, they can be divided into two groups: (i) monophase flow, where miscible (e.g. aqueous) fluids are mixed, mostly by diffusion owing to the laminar flow on small length scales and (ii) multiphase flow, the most prominent example of which is probably droplet microfluidics, where water-in-oil or oil-in-water emulsions are used to encapsulate chemical or biological systems and separate them from each other, much like in 'micron-scale test tubes'. Now, 30 years later, microfluidic techniques are seriously considered for industrial applications, although some important steps in the upscaling process are still missing. The purpose of this special issue is to shed light on the different aspects in microfluidics research starting from fundamental research reaching all the way to industrial applications. The study by Toma and co-workers takes advantage of the controlled diffusive mixing when co-flowing aqueous, miscible solutions. They combine microfluidics with optical, spectroscopic and scattering techniques to study DNA packing. Nunes et al review the different regimes when replacing one of the fluids by an oil phase and varying flow rates and device geometries with a particular emphasis on using multiphase microfluidics for synthesis of particles or fibres. Going into the third dimension by fabricating microfluidic devices with several layers, producing emulsions can also be achieved by so-called 'step emulsification', the physical mechanisms behind which are described by Dangla et al. Tran and co-workers move a considerable step towards applicability of water-in-oil emulsions for biological research and review ultrahigh-throughput methods used for bio-assays. The article by Lagus et al focuses this topic specifically on single-cell experiments. Whereas it is very popular to use emulsions with drop sizes of a few tens of micrometers as 'tiny test tubes' they may also serve as templates for materials fabrication. Gundabala and co-workers combine both aspects by producing so-called 'celloidosomes', which consist of liquid drops decorated with yeast cells at the outer interface. Wang et al fabricate microcrawlers that can be thermally set in motion. Finally, Holtze gives a perspective on the possibility to upscale and apply such methods in industry. The choice of papers shows the wide and diverse applicability of microfluidics in various fields of research. While microfluidics started out as a 'niche' technique for very specific applications and as a tool in fundamental soft and biological matter research, the advancements made during recent years promise further progress in the chemical industry, biomedicine and pharmacology. Advantages such as low sample consumption, single cell accessibility and controlled experimental parameters in general may in the future be exploited for real industrial sized applications. In Journal of Physics D: Applied Physics we find a journal that is ideally positioned to give applied microfluidics research a wide readership across many disciplines. In the publication of this special issue we hope to inspire and encourage microfluidics researchers, and to promote interdisciplinary collaborations. We would like to thank all of the authors for their excellent contributions to this special issue.

Accessible intergration of agriculture, groundwater, and economic models using the Open Modeling Interface (Open MI): methodology and initial results

USDA-ARS?s Scientific Manuscript database

Policy for water resources impacts not only hydrological processes, but the closely intertwined economic and social processes dependent on them. Understanding these process interactions across domains is an important step in establishing effective and sustainable policy. Multidisciplinary integrated...

Open access behaviours and perceptions of health sciences faculty and roles of information professionals.

PubMed

Lwoga, Edda T; Questier, Frederik

2015-03-01

This study sought to investigate the faculty's awareness, attitudes and use of open access, and the role of information professionals in supporting open access (OA) scholarly communication in Tanzanian health sciences universities. A cross-sectional survey was conducted. Semi-structured interviews were conducted with 16 librarians, while questionnaires were physically distributed to 415 faculty members in all eight Tanzanian health sciences universities, with a response rate of 71.1%. The study found that most faculty members were aware about OA issues. However, the high level of OA awareness among faculty members did not translate into actual dissemination of faculty's research outputs through OA web avenues. A small proportion of faculty's research materials was made available as OA. Faculty were more engaged with OA journal publishing than with self-archiving practices. Senior faculty with proficient technical skills were more likely to use open access than junior faculty. Major barriers to OA usage were related to ICT infrastructure, awareness, skills, author-pay model, and copyright and plagiarism concerns. Interviews with librarians revealed that there was a strong support for promoting OA issues on campus; however, this positive support with various open access-related tasks did not translate into actual action. It is thus important for librarians and OA administrators to consider all these factors for effective implementation of OA projects in research and academic institutions. This is the first comprehensive and detailed study focusing on the health sciences faculty's and librarians' behaviours and perceptions of open access initiatives in Tanzania and reveals findings that are useful for planning and implementing open access initiatives in other institutions with similar conditions. © 2015 Health Libraries Journal.

Registered access: a 'Triple-A' approach.

PubMed

Dyke, Stephanie O M; Kirby, Emily; Shabani, Mahsa; Thorogood, Adrian; Kato, Kazuto; Knoppers, Bartha M

2016-12-01

We propose a standard model for a novel data access tier - registered access - to facilitate access to data that cannot be published in open access archives owing to ethical and legal risk. Based on an analysis of applicable research ethics and other legal and administrative frameworks, we discuss the general characteristics of this Registered Access Model, which would comprise a three-stage approval process: Authentication, Attestation and Authorization. We are piloting registered access with the Demonstration Projects of the Global Alliance for Genomics and Health for which it may provide a suitable mechanism for access to certain data types and to different types of data users.

A digital microfluidic system for serological immunoassays in remote settings.

PubMed

Ng, Alphonsus H C; Fobel, Ryan; Fobel, Christian; Lamanna, Julian; Rackus, Darius G; Summers, Aimee; Dixon, Christopher; Dryden, Michael D M; Lam, Charis; Ho, Man; Mufti, Nooman S; Lee, Victor; Asri, Mohd Afiq Mohd; Sykes, Edward A; Chamberlain, M Dean; Joseph, Rachael; Ope, Maurice; Scobie, Heather M; Knipes, Alaine; Rota, Paul A; Marano, Nina; Chege, Paul M; Njuguna, Mary; Nzunza, Rosemary; Kisangau, Ngina; Kiogora, John; Karuingi, Michael; Burton, John Wagacha; Borus, Peter; Lam, Eugene; Wheeler, Aaron R

2018-04-25

Serosurveys are useful for assessing population susceptibility to vaccine-preventable disease outbreaks. Although at-risk populations in remote areas could benefit from this type of information, they face several logistical barriers to implementation, such as lack of access to centralized laboratories, cold storage, and transport of samples. We describe a potential solution: a compact and portable, field-deployable, point-of-care system relying on digital microfluidics that can rapidly test a small volume of capillary blood for disease-specific antibodies. This system uses inexpensive, inkjet-printed digital microfluidic cartridges together with an integrated instrument to perform enzyme-linked immunosorbent assays (ELISAs). We performed a field validation of the system's analytical performance at Kakuma refugee camp, a remote setting in northwestern Kenya, where we tested children aged 9 to 59 months and caregivers for measles and rubella immunoglobulin G (IgG). The IgG assays were determined to have sensitivities of 86% [95% confidence interval (CI), 79 to 91% (measles)] and 81% [95% CI, 73 to 88% (rubella)] and specificities of 80% [95% CI, 49 to 94% (measles)] and 91% [95% CI, 76 to 97% (rubella)] (measles, n = 140; rubella, n = 135) compared with reference tests (measles IgG and rubella IgG ELISAs from Siemens Enzygnost) conducted in a centralized laboratory. These results demonstrate a potential role for this point-of-care system in global serological surveillance, particularly in remote areas with limited access to centralized laboratories. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

The Open Microscopy Environment: open image informatics for the biological sciences

NASA Astrophysics Data System (ADS)

Blackburn, Colin; Allan, Chris; Besson, Sébastien; Burel, Jean-Marie; Carroll, Mark; Ferguson, Richard K.; Flynn, Helen; Gault, David; Gillen, Kenneth; Leigh, Roger; Leo, Simone; Li, Simon; Lindner, Dominik; Linkert, Melissa; Moore, Josh; Moore, William J.; Ramalingam, Balaji; Rozbicki, Emil; Rustici, Gabriella; Tarkowska, Aleksandra; Walczysko, Petr; Williams, Eleanor; Swedlow, Jason R.

2016-07-01

Despite significant advances in biological imaging and analysis, major informatics challenges remain unsolved: file formats are proprietary, storage and analysis facilities are lacking, as are standards for sharing image data and results. While the open FITS file format is ubiquitous in astronomy, astronomical imaging shares many challenges with biological imaging, including the need to share large image sets using secure, cross-platform APIs, and the need for scalable applications for processing and visualization. The Open Microscopy Environment (OME) is an open-source software framework developed to address these challenges. OME tools include: an open data model for multidimensional imaging (OME Data Model); an open file format (OME-TIFF) and library (Bio-Formats) enabling free access to images (5D+) written in more than 145 formats from many imaging domains, including FITS; and a data management server (OMERO). The Java-based OMERO client-server platform comprises an image metadata store, an image repository, visualization and analysis by remote access, allowing sharing and publishing of image data. OMERO provides a means to manage the data through a multi-platform API. OMERO's model-based architecture has enabled its extension into a range of imaging domains, including light and electron microscopy, high content screening, digital pathology and recently into applications using non-image data from clinical and genomic studies. This is made possible using the Bio-Formats library. The current release includes a single mechanism for accessing image data of all types, regardless of original file format, via Java, C/C++ and Python and a variety of applications and environments (e.g. ImageJ, Matlab and R).

Open access of evidence-based publications: the case of the orthopedic and musculoskeletal literature.

PubMed

Yammine, Kaissar

2015-11-01

The open access model, where researchers can publish their work and make it freely available to the whole medical community, is gaining ground over the traditional type of publication. However, fees are to be paid by either the authors or their institutions. The purpose of this paper is to assess the proportion and type of open access evidence-based articles in the form of systematic reviews and meta-analyses in the field of musculoskeletal disorders and orthopedic surgery. PubMed database was searched and the results showed a maximal number of hits for low back pain and total hip arthroplasty. We demonstrated that despite a 10-fold increase in the number of evidence-based publications in the past 10 years, the rate of free systematic reviews in the general biomedical literature did not change for the last two decades. In addition, the average percentage of free open access systematic reviews and meta-analyses for the commonest painful musculoskeletal conditions and orthopedic procedures was 20% and 18%, respectively. Those results were significantly lower than those of the systematic reviews and meta-analyses in the remaining biomedical research. Such findings could indicate a divergence between the efforts engaged at promoting evidence-based principles and those at disseminating evidence-based findings in the field of musculoskeletal disease and trauma. The high processing fee is thought to be a major limitation when considering open access model for publication. © 2015 Chinese Cochrane Center, West China Hospital of Sichuan University and Wiley Publishing Asia Pty Ltd.

Optics-Integrated Microfluidic Platforms for Biomolecular Analyses

PubMed Central

Bates, Kathleen E.; Lu, Hang

2016-01-01

Compared with conventional optical methods, optics implemented on microfluidic chips provide small, and often much cheaper ways to interrogate biological systems from the level of single molecules up to small model organisms. The optical probing of single molecules has been used to investigate the mechanical properties of individual biological molecules; however, multiplexing of these measurements through microfluidics and nanofluidics confers many analytical advantages. Optics-integrated microfluidic systems can significantly simplify sample processing and allow a more user-friendly experience; alignments of on-chip optical components are predetermined during fabrication and many purely optical techniques are passively controlled. Furthermore, sample loss from complicated preparation and fluid transfer steps can be virtually eliminated, a particularly important attribute for biological molecules at very low concentrations. Excellent fluid handling and high surface area/volume ratios also contribute to faster detection times for low abundance molecules in small sample volumes. Although integration of optical systems with classical microfluidic analysis techniques has been limited, microfluidics offers a ready platform for interrogation of biophysical properties. By exploiting the ease with which fluids and particles can be precisely and dynamically controlled in microfluidic devices, optical sensors capable of unique imaging modes, single molecule manipulation, and detection of minute changes in concentration of an analyte are possible. PMID:27119629

Linking the open source, spatial electrification tool (ONSSET) and the open source energy modelling system (OSeMOSYS), with a focus on Sub-Saharan Africa

NASA Astrophysics Data System (ADS)

Mentis, Dimitrios; Howells, Mark; Rogner, Holger; Korkovelos, Alexandros; Arderne, Christopher; Siyal, Shahid; Zepeda, Eduardo; Taliotis, Constantinos; Bazilian, Morgan; de Roo, Ad; Tanvez, Yann; Oudalov, Alexandre; Scholtz, Ernst

2017-04-01

In September 2015, the United Nations General Assembly adopted Agenda 2030, which comprises a set of 17 Sustainable Development Goals (SDGs) defined by 169 targets. "Ensuring access to affordable, reliable, sustainable and modern energy for all by 2030" is the seventh goal (SDG7). While access to energy refers to more than electricity, the latter is the central focus of this work. According to the World Bank's 2015 Global Tracking Framework, roughly 15% of world population (or 1.1 billion people) lack access to electricity, and many more rely on poor quality electricity services. The majority of those without access (87%) reside in rural areas. This paper presents results of a Geographic Information Systems (GIS) approach coupled with open access data and linked to the Electricity Model Base for Africa (TEMBA), a model that represents each continental African country's electricity supply system. We present least-cost electrification strategies on a country-by-country basis for Sub-Saharan Africa. The electrification options include grid extension, mini-grid and stand-alone systems for rural, peri-urban, and urban contexts across the economy. At low levels of electricity demand there is a strong penetration of standalone technologies. However, higher electricity demand levels move the favourable electrification option from stand-alone systems to mini grid and to grid extensions.

Design and Characterization of a High Resolution Microfluidic Heat Flux Sensor with Thermal Modulation

PubMed Central

Nam, Sung-Ki; Kim, Jung-Kyun; Cho, Sung-Cheon; Lee, Sun-Kyu

2010-01-01

A complementary metal-oxide semiconductor-compatible process was used in the design and fabrication of a suspended membrane microfluidic heat flux sensor with a thermopile for the purpose of measuring the heat flow rate. The combination of a thirty-junction gold and nickel thermoelectric sensor with an ultralow noise preamplifier, a low pass filter, and a lock-in amplifier can yield a resolution 20 nW with a sensitivity of 461 V/W. The thermal modulation method is used to eliminate low-frequency noise from the sensor output, and various amounts of fluidic heat were applied to the sensor to investigate its suitability for microfluidic applications. For sensor design and analysis of signal output, a method of modeling and simulating electro-thermal behavior in a microfluidic heat flux sensor with an integrated electronic circuit is presented and validated. The electro-thermal domain model was constructed by using system dynamics, particularly the bond graph. The electro-thermal domain system model in which the thermal and the electrical domains are coupled expresses the heat generation of samples and converts thermal input to electrical output. The proposed electro-thermal domain system model is in good agreement with the measured output voltage response in both the transient and the steady state. PMID:22163568

Milestones and impact factors.

PubMed

Ozonoff, David M; Grandjean, Philippe

2010-07-08

Environmental Health has just received its first Impact Factor by Thomson ISI. At a level of 2.48, this achievement is quite satisfactory and places Environmental Health in the top 25% of environmental science journals. When the journal was launched in 2002, it was still unclear whether the Open Access publishing model could be made into a viable commercial enterprise within the biomedical field. During the past eight years, Open Access journals have become widely available, although still covering only about 15% of journal titles. Major funding agencies and institutions, including prominent US universities, now require that researchers publish in Open Access journals. Because of the profound role of scientific journals for the sharing of results and communication between researchers, the advent of Open Access may be of as much significance as the transition from handwriting to printing via moveable type. As Environmental Health is an electronic Open Access journal, the numbers of downloads at the journal website can be retrieved. The top-20 list of articles most frequently accessed shows that all of them have been downloaded over 10,000 times. Back in 2002, the first article published was accessed only 49 times during the following month. A year later, the server had over 1,000 downloads per month, and now the total number of monthly downloads approaches 50,000. These statistics complement the Impact Factor and confirm the viability of Open Access in our field of research. The advent of digital media and its decentralized mode of distribution - the internet - have dramatically changed the control and financing of scientific information dissemination, while facilitating peer review, accelerating editorial handling, and supporting much needed transparency. Both the meaning and means of "having an impact" are therefore changing, as will the degree and way in which scientific journals remain "factors" in that impact.

Milestones and Impact Factors

PubMed Central

2010-01-01

Environmental Health has just received its first Impact Factor by Thomson ISI. At a level of 2.48, this achievement is quite satisfactory and places Environmental Health in the top 25% of environmental science journals. When the journal was launched in 2002, it was still unclear whether the Open Access publishing model could be made into a viable commercial enterprise within the biomedical field. During the past eight years, Open Access journals have become widely available, although still covering only about 15% of journal titles. Major funding agencies and institutions, including prominent US universities, now require that researchers publish in Open Access journals. Because of the profound role of scientific journals for the sharing of results and communication between researchers, the advent of Open Access may be of as much significance as the transition from handwriting to printing via moveable type. As Environmental Health is an electronic Open Access journal, the numbers of downloads at the journal website can be retrieved. The top-20 list of articles most frequently accessed shows that all of them have been downloaded over 10,000 times. Back in 2002, the first article published was accessed only 49 times during the following month. A year later, the server had over 1,000 downloads per month, and now the total number of monthly downloads approaches 50,000. These statistics complement the Impact Factor and confirm the viability of Open Access in our field of research. The advent of digital media and its decentralized mode of distribution - the internet - have dramatically changed the control and financing of scientific information dissemination, while facilitating peer review, accelerating editorial handling, and supporting much needed transparency. Both the meaning and means of "having an impact" are therefore changing, as will the degree and way in which scientific journals remain "factors" in that impact. PMID:20615249

Revisiting lab-on-a-chip technology for drug discovery.

PubMed

Neuži, Pavel; Giselbrecht, Stefan; Länge, Kerstin; Huang, Tony Jun; Manz, Andreas

2012-08-01

The field of microfluidics or lab-on-a-chip technology aims to improve and extend the possibilities of bioassays, cell biology and biomedical research based on the idea of miniaturization. Microfluidic systems allow more accurate modelling of physiological situations for both fundamental research and drug development, and enable systematic high-volume testing for various aspects of drug discovery. Microfluidic systems are in development that not only model biological environments but also physically mimic biological tissues and organs; such 'organs on a chip' could have an important role in expediting early stages of drug discovery and help reduce reliance on animal testing. This Review highlights the latest lab-on-a-chip technologies for drug discovery and discusses the potential for future developments in this field.

Stereo Vision Inside Tire

DTIC Science & Technology

2015-08-21

using the Open Computer Vision ( OpenCV ) libraries [6] for computer vision and the Qt library [7] for the user interface. The software has the...depth. The software application calibrates the cameras using the plane based calibration model from the OpenCV calib3D module and allows the...6] OpenCV . 2015. OpenCV Open Source Computer Vision. [Online]. Available at: opencv.org [Accessed]: 09/01/2015. [7] Qt. 2015. Qt Project home

A novel flexible microfluidic meshwork to reduce fibrosis in glaucoma surgery.

PubMed

Amoozgar, Behzad; Wei, Xiaoling; Hui Lee, Jun; Bloomer, Michele; Zhao, Zhengtuo; Coh, Paul; He, Fei; Luan, Lan; Xie, Chong; Han, Ying

2017-01-01

Fibrosis and hence capsule formation around the glaucoma implants are the main reasons for glaucoma implant failure. To address these issues, we designed a microfluidic meshwork and tested its biocompatibility in a rabbit eye model. The amount of fibrosis elicited by the microfluidic meshwork was compared to the amount elicited by the plate of conventional glaucoma drainage device. Six eyes from 3 New Zealand albino rabbits were randomized to receive either the novel microfluidic meshwork or a plate of Ahmed glaucoma valve model PF7 (AGV PF7). The flexible microfluidic implant was made from negative photoresist SU-8 by using micro-fabrication techniques. The overall size of the meshwork was 7 mm × 7 mm with a grid period of 100 μm. Both implants were placed in the subtenon space at the supratemporal quadrant in a standard fashion. There was no communication between the implants and the anterior chamber via a tube. All animal eyes were examined for signs of infection and implant erosion on days 1, 3, 7, and 14 and then monthly. Exenterations were performed in which the entire orbital contents were removed at 3 months. Histology slides of the implant and the surrounding tissues were prepared and stained with hematoxylin-eosin. Thickness of the fibrous capsules beneath the implants were measured and compared with paired student's t-test between the two groups. The gross histological sections showed that nearly no capsule formed around the microfluidic meshwork in contrast to the thick capsule formed around the plate of AGV PF7. Thickness of the fibrotic capsules beneath the AGV PF7 plate from the 3 rabbit eyes was 90μm, 82μm, and 95 μm, respectively. The thickness at the bottom of fibrotic capsules around the new microfluidic implant were 1μm, 2μm, and 1μm, respectively. The difference in thickness of capsule between the two groups was significant (P = 0.002). No complications were noticed in the 6 eyes, and both implants were tolerated well by all rabbits. The microfluidic meshwork elicited minimal fibrosis and capsule formation after 3-months implantation in a rabbit model. This provides promising evidence to aid in future development of a new glaucoma drainage implant that will elicit minimal scar formation and provide better long-term surgical outcomes.

Imaging label-free biosensor with microfluidic system

NASA Astrophysics Data System (ADS)

Jahns, S.; Glorius, P.; Hansen, M.; Nazirizadeh, Y.; Gerken, M.

2015-06-01

We present a microfluidic system suitable for parallel label-free detection of several biomarkers utilizing a compact imaging measurement system. The microfluidic system contains a filter unit to separate the plasma from human blood and a functionalized, photonic crystal slab sensor chip. The nanostructure of the photonic crystal slab sensor chip is fabricated by nanoimprint lithography of a period grating surface into a photoresist and subsequent deposition of a TiO2 layer. Photonic crystal slabs are slab waveguides supporting quasi-guided modes coupling to far-field radiation, which are sensitive to refractive index changes due to biomarker binding on the functionalized surface. In our imaging read-out system the resulting resonance shift of the quasi-guided mode in the transmission spectrum is converted into an intensity change detectable with a simple camera. By continuously taking photographs of the sensor surface local intensity changes are observed revealing the binding kinetics of the biomarker to its specific target. Data from two distinct measurement fields are used for evaluation. For testing the sensor chip, 1 μM biotin as well as 1 μM recombinant human CD40 ligand were immobilized in spotsvia amin coupling to the sensor surface. Each binding experiment was performed with 250 nM streptavidin and 90 nM CD40 ligand antibody dissolved in phosphate buffered saline. In the next test series, a functionalized sensor chip was bonded onto a 15 mm x 15 mm opening of the 75 mm x 25 mm x 2 mm microfluidic system. We demonstrate the functionality of the microfluidic system for filtering human blood such that only blood plasma was transported to the sensor chip. The results of first binding experiments in buffer with this test chip will be presented.

A microfluidic device for dry sample preservation in remote settings.

PubMed

Begolo, Stefano; Shen, Feng; Ismagilov, Rustem F

2013-11-21

This paper describes a microfluidic device for dry preservation of biological specimens at room temperature that incorporates chemical stabilization matrices. Long-term stabilization of samples is crucial for remote medical analysis, biosurveillance, and archiving, but the current paradigm for transporting remotely obtained samples relies on the costly "cold chain" to preserve analytes within biospecimens. We propose an alternative approach that involves the use of microfluidics to preserve samples in the dry state with stabilization matrices, developed by others, that are based on self-preservation chemistries found in nature. We describe a SlipChip-based device that allows minimally trained users to preserve samples with the three simple steps of placing a sample at an inlet, closing a lid, and slipping one layer of the device. The device fills automatically, and a pre-loaded desiccant dries the samples. Later, specimens can be rehydrated and recovered for analysis in a laboratory. This device is portable, compact, and self-contained, so it can be transported and operated by untrained users even in limited-resource settings. Features such as dead-end and sequential filling, combined with a "pumping lid" mechanism, enable precise quantification of the original sample's volume while avoiding overfilling. In addition, we demonstrated that the device can be integrated with a plasma filtration module, and we validated device operations and capabilities by testing the stability of purified RNA solutions. These features and the modularity of this platform (which facilitates integration and simplifies operation) would be applicable to other microfluidic devices beyond this application. We envision that as the field of stabilization matrices develops, microfluidic devices will be useful for cost-effectively facilitating remote analysis and biosurveillance while also opening new opportunities for diagnostics, drug development, and other medical fields.

Microbioreactors with microfluidic control and a user-friendly connection to the actuator hardware

NASA Astrophysics Data System (ADS)

Buchenauer, A.; Funke, M.; Büchs, J.; Mokwa, W.; Schnakenberg, U.

2009-07-01

In this study, an array of microbioreactors based on the format of 48-well microtiter plates (MTPs) is presented. The process parameters pH and biomass are monitored online using commercially available optical sensor technology. A microfluidic device dispenses acid or base individually into each well for controlling the pH of fermentations. Fluid volumes from 72 nL to 940 nL can be supplied with valve opening times between 10 ms and 200 ms. One microfluidic device is capable of supplying four wells from two reservoirs. Up to four microfluidic devices can be integrated on the area of a prototype MTP. The devices are fabricated in polydimethylsiloxane (PDMS) using soft lithographic techniques and utilize pneumatically actuated microvalves. During fermentations, the microbioreactor is clamped to an orbital shaker and a temporary pneumatic connection guides the externally controlled pressurized air to the microfluidic device. Finally, fermentations of Escherichia coli in the presence and absence of pH control are carried out in the microbioreactor system over 18 h. During the fermentation the pH of the cultures is continuously monitored by means of optodes. An ammonia solution or phosphoric acid is dispensed to adjust the pH if it differs from the set point of 7.2. In a controlled culture, the pH can be sustained within 7.0 to 7.3 while the pH in an uncontrolled culture ranges between 6.5 and 9.0. This microbioreactor demonstrates the possibility of pH-controlled fermentations in micro-scale. The process control and the user friendly connection to the actuation hardware provide an easy handling comparable to standard MTPs.

Application of microfluidic technologies to human assisted reproduction

PubMed Central

Takayama, Shuichi

2017-01-01

Abstract Microfluidics can be considered both a science and a technology. It is defined as the study of fluid behavior at a sub-microliter level and the investigation into its application to cell biology, chemistry, genetics, molecular biology and medicine. There are at least two characteristics of microfluidics, mechanical and biochemical, which can be influential in the field of mammalian gamete and preimplantation embryo biology. These microfluidic characteristics can assist in basic biological studies on sperm, oocyte and preimplantation embryo structure, function and environment. The mechanical and biochemical characteristics of microfluidics may also have practical and/or technical application(s) to assisted reproductive technologies (ART) in rodents, domestic species, endangered species and humans. This review will consider data in mammals, and when available humans, addressing the potential application(s) of microfluidics to assisted reproduction. There are numerous sequential steps in the clinical assisted reproductive laboratory process that work, yet could be improved. Cause and effect relations of procedural inefficiencies can be difficult to identify and/or remedy. Data will be presented that consider microfluidic applications to sperm isolation, oocyte cumulus complex isolation, oocyte denuding, oocyte mechanical manipulation, conventional insemination, intracytoplasmic sperm injection, embryo culture, embryo analysis and oocyte and embryo cryopreservation. While these studies have progressed in animal models, data with human gametes and embryos are significantly lacking. These data from clinical trials are requisite for making future evidence-based decisions regarding the application of microfluidics in human ART. PMID:28130394

Exploration of microfluidic devices based on multi-filament threads and textiles: A review

PubMed Central

Nilghaz, A.; Ballerini, D. R.; Shen, W.

2013-01-01

In this paper, we review the recent progress in the development of low-cost microfluidic devices based on multifilament threads and textiles for semi-quantitative diagnostic and environmental assays. Hydrophilic multifilament threads are capable of transporting aqueous and non-aqueous fluids via capillary action and possess desirable properties for building fluid transport pathways in microfluidic devices. Thread can be sewn onto various support materials to form fluid transport channels without the need for the patterned hydrophobic barriers essential for paper-based microfluidic devices. Thread can also be used to manufacture fabrics which can be patterned to achieve suitable hydrophilic-hydrophobic contrast, creating hydrophilic channels which allow the control of fluids flow. Furthermore, well established textile patterning methods and combination of hydrophilic and hydrophobic threads can be applied to fabricate low-cost microfluidic devices that meet the low-cost and low-volume requirements. In this paper, we review the current limitations and shortcomings of multifilament thread and textile-based microfluidics, and the research efforts to date on the development of fluid flow control concepts and fabrication methods. We also present a summary of different methods for modelling the fluid capillary flow in microfluidic thread and textile-based systems. Finally, we summarized the published works of thread surface treatment methods and the potential of combining multifilament thread with other materials to construct devices with greater functionality. We believe these will be important research focuses of thread- and textile-based microfluidics in future. PMID:24086179

Dynamics of blood flow in a microfluidic ladder network

NASA Astrophysics Data System (ADS)

Maddala, Jeevan; Zilberman-Rudenko, Jevgenia; McCarty, Owen

The dynamics of a complex mixture of cells and proteins, such as blood, in perturbed shear flow remains ill-defined. Microfluidics is a promising technology for improving the understanding of blood flow under complex conditions of shear; as found in stent implants and in tortuous blood vessels. We model the fluid dynamics of blood flow in a microfluidic ladder network with dimensions mimicking venules. Interaction of blood cells was modeled using multiagent framework, where cells of different diameters were treated as spheres. This model served as the basis for predicting transition regions, collision pathways, re-circulation zones and residence times of cells dependent on their diameters and device architecture. Based on these insights from the model, we were able to predict the clot formation configurations at various locations in the device. These predictions were supported by the experiments using whole blood. To facilitate platelet aggregation, the devices were coated with fibrillar collagen and tissue factor. Blood was perfused through the microfluidic device for 9 min at a physiologically relevant venous shear rate of 600 s-1. Using fluorescent microscopy, we observed flow transitions near the channel intersections and at the areas of blood flow obstruction, which promoted larger thrombus formation. This study of integrating model predictions with experimental design, aids in defining the dynamics of blood flow in microvasculature and in development of novel biomedical devices.

Fabrication and Evaluation of Microfluidic Immunoassay Devices with Antibody-Immobilized Microbeads Retained in Porous Hydrogel Micropillars.

PubMed

Kasama, Toshihiro; Kaji, Noritada; Tokeshi, Manabu; Baba, Yoshinobu

2017-01-01

Due to the inherent characteristics including confinement of molecular diffusion and high surface-to-volume ratio, microfluidic device-based immunoassay has great advantages in cost, speed, sensitivity, and so on, compared with conventional techniques such as microtiter plate-based ELISA, latex agglutination method, and lateral flow immunochromatography. In this paper, we explain the detection of C-reactive protein as a model antigen by using our microfluidic immunoassay device, so-called immuno-pillar device. We describe in detail how we fabricated and used the immuno-pillar devices.

Spontaneous oscillations in microfluidic networks

NASA Astrophysics Data System (ADS)

Case, Daniel; Angilella, Jean-Regis; Motter, Adilson

2017-11-01

Precisely controlling flows within microfluidic systems is often difficult which typically results in systems being heavily reliant on numerous external pumps and computers. Here, I present a simple microfluidic network that exhibits flow rate switching, bistablity, and spontaneous oscillations controlled by a single pressure. That is, by solely changing the driving pressure, it is possible to switch between an oscillating and steady flow state. Such functionality does not rely on external hardware and may even serve as an on-chip memory or timing mechanism. I use an analytic model and rigorous fluid dynamics simulations to show these results.

50 CFR 660.332 - Open access daily trip limit (DTL) fishery for sablefish.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Open access daily trip limit (DTL) fishery... COAST STATES West Coast Groundfish-Open Access Fisheries § 660.332 Open access daily trip limit (DTL) fishery for sablefish. (a) Open access DTL fisheries both north and south of 36° N. lat. Open access...

Design, fabrication and test of a pneumatically controlled, renewable, microfluidic bead trapping device for sequential injection analysis applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shao, Guocheng; Lu, Donglai; Fu, Zhifeng

This paper describes the design, fabrication, and testing of a pneumatically controlled,renewable, microfluidic device for conducting bead-based assays in an automated sequential injection analysis system. The device used a “brick wall”-like pillar array (pillar size: 20 μm length X 50 μm width X 45 μm height) with 5 μm gaps between the pillars serving as the micro filter. The flow channel where bead trapping occurred is 500 μm wide X 75 μm deep. An elastomeric membrane and an air chamber were located underneath the flow channel. By applying pressure to the air chamber, the membrane is deformed and pushed upwardmore » against the filter structure. This effectively traps beads larger than 5 μm and creates a “bed” or micro column of beads that can be perfused and washed with liquid samples and reagents. Upon completion of the assay process, the pressure is released and the beads are flushed out from underneath the filter structure to renew the device. Mouse IgG was used as a model analyte to test the feasibility of using the proposed device for immunoassay applications. Resulting microbeads from an on-chip fluorescent immunoassay were individually examined using flow cytometry. The results show that the fluorescence signal intensity distribution is fairly narrow indicating high chemical reaction uniformity among the beads population. Electrochemical onchip assay was also conducted. A detection limit of 0.1 ng/mL1 ppb was achieved and good device reliability and repeatability were demonstrated. The novel microfluidic-based beadstrapping device thus opens up a new pathway to design micro-bead based biosensor immunoassays for clinical and othervarious applications.« less

New perspectives on neuronal development via microfluidic environments

PubMed Central

Millet, Larry J.; Gillette, Martha U.

2012-01-01

Understanding the signals that guide neuronal development and direct formation of axons, dendrites, and synapses during wiring of the brain is a fundamental challenge of developmental neuroscience. Discovering how local signals shape developing neurons has been impeded by the inability of conventional culture methods to interrogate micro-environments of complex neuronal cytoarchitectures, where different sub-domains encounter distinct chemical, physical, and fluidic features. Micro-fabrication techniques are enabling the creation of micro-environments tailored to neuronal structures and sub-domains, with unprecedented access and control. The design, fabrication, and properties of microfluidic devices offer significant advantages for addressing unresolved issues of neuronal development. These high-resolution approaches are poised to contribute new insights into mechanisms for restoring neuronal function and connectivity compromised by injury, stress, and neurodegeneration. PMID:23031246

OpenClimateGIS - A Web Service Providing Climate Model Data in Commonly Used Geospatial Formats

NASA Astrophysics Data System (ADS)

Erickson, T. A.; Koziol, B. W.; Rood, R. B.

2011-12-01

The goal of the OpenClimateGIS project is to make climate model datasets readily available in commonly used, modern geospatial formats used by GIS software, browser-based mapping tools, and virtual globes.The climate modeling community typically stores climate data in multidimensional gridded formats capable of efficiently storing large volumes of data (such as netCDF, grib) while the geospatial community typically uses flexible vector and raster formats that are capable of storing small volumes of data (relative to the multidimensional gridded formats). OpenClimateGIS seeks to address this difference in data formats by clipping climate data to user-specified vector geometries (i.e. areas of interest) and translating the gridded data on-the-fly into multiple vector formats. The OpenClimateGIS system does not store climate data archives locally, but rather works in conjunction with external climate archives that expose climate data via the OPeNDAP protocol. OpenClimateGIS provides a RESTful API web service for accessing climate data resources via HTTP, allowing a wide range of applications to access the climate data.The OpenClimateGIS system has been developed using open source development practices and the source code is publicly available. The project integrates libraries from several other open source projects (including Django, PostGIS, numpy, Shapely, and netcdf4-python).OpenClimateGIS development is supported by a grant from NOAA's Climate Program Office.

Microfluidics as a functional tool for cell mechanics.

PubMed

Vanapalli, Siva A; Duits, Michel H G; Mugele, Frieder

2009-01-05

Living cells are a fascinating demonstration of nature's most intricate and well-coordinated micromechanical objects. They crawl, spread, contract, and relax-thus performing a multitude of complex mechanical functions. Alternatively, they also respond to physical and chemical cues that lead to remodeling of the cytoskeleton. To understand this intricate coupling between mechanical properties, mechanical function and force-induced biochemical signaling requires tools that are capable of both controlling and manipulating the cell microenvironment and measuring the resulting mechanical response. In this review, the power of microfluidics as a functional tool for research in cell mechanics is highlighted. In particular, current literature is discussed to show that microfluidics powered by soft lithographic techniques offers the following capabilities that are of significance for understanding the mechanical behavior of cells: (i) Microfluidics enables the creation of in vitro models of physiological environments in which cell mechanics can be probed. (ii) Microfluidics is an excellent means to deliver physical cues that affect cell mechanics, such as cell shape, fluid flow, substrate topography, and stiffness. (iii) Microfluidics can also expose cells to chemical cues, such as growth factors and drugs, which alter their mechanical behavior. Moreover, these chemical cues can be delivered either at the whole cell or subcellular level. (iv) Microfluidic devices offer the possibility of measuring the intrinsic mechanical properties of cells in a high throughput fashion. (v) Finally, microfluidic methods provide exquisite control over drop size, generation, and manipulation. As a result, droplets are being increasingly used to control the physicochemical environment of cells and as biomimetic analogs of living cells. These powerful attributes of microfluidics should further stimulate novel means of investigating the link between physicochemical cues and the biomechanical response of cells. Insights from such studies will have implications in areas such as drug delivery, medicine, tissue engineering, and biomedical diagnostics.

An open science approach to modeling and visualizing ...

EPA Pesticide Factsheets

It is expected that cyanobacteria blooms will increase in frequency, duration, and severity as inputs of nutrients increase and the impacts of climate change are realized. Partly in response to this, federal, state, and local entities have ramped up efforts to better understand blooms which has resulted in new life for old datasets, new monitoring programs, and novel uses for non-traditional sources of data. To fully benefit from these datasets, it is also imperative that the full body of work including data, code, and manuscripts be openly available (i.e., open science). This presentation will provide several examples of our work which occurs at the intersection of open science and research on cyanobacetria blooms in lakes and ponds. In particular we will discuss 1) why open science is particularly important for environmental human health issues; 2) the lakemorpho and elevatr R packages and how we use those to model lake morphometry; 3) Shiny server applications to visualize data collected as part of the Cyanobacteria Monitoring Collaborative; and 4) distribution of our research and models via open access publications and as R packages on GitHub. Modelling and visualizing information on cyanobacteria blooms is important as it provides estimates of the extent of potential problems associated with these blooms. Furthermore, conducting this work in the open allows others to access our code, data, and results. In turn, this allows for a greater impact because the

Temperature-programmed natural convection for micromixing and biochemical reaction in a single microfluidic chamber.

PubMed

Kim, Sung-Jin; Wang, Fang; Burns, Mark A; Kurabayashi, Katsuo

2009-06-01

Micromixing is a crucial step for biochemical reactions in microfluidic networks. A critical challenge is that the system containing micromixers needs numerous pumps, chambers, and channels not only for the micromixing but also for the biochemical reactions and detections. Thus, a simple and compatible design of the micromixer element for the system is essential. Here, we propose a simple, yet effective, scheme that enables micromixing and a biochemical reaction in a single microfluidic chamber without using any pumps. We accomplish this process by using natural convection in conjunction with alternating heating of two heaters for efficient micromixing, and by regulating capillarity for sample transport. As a model application, we demonstrate micromixing and subsequent polymerase chain reaction (PCR) for an influenza viral DNA fragment. This process is achieved in a platform of a microfluidic cartridge and a microfabricated heating-instrument with a fast thermal response. Our results will significantly simplify micromixing and a subsequent biochemical reaction that involves reagent heating in microfluidic networks.

Apparent Softening of Wet Graphene Membranes on a Microfluidic Platform.

PubMed

Ferrari, Gustavo A; de Oliveira, Alan B; Silvestre, Ive; Matos, Matheus J S; Batista, Ronaldo J C; Fernandes, Thales F D; Meireles, Leonel M; Eliel, Gomes S N; Chacham, Helio; Neves, Bernardo R A; Lacerda, Rodrigo G

2018-05-22

Graphene is regarded as the toughest two-dimensional material (highest in-plane elastic properties) and, as a consequence, it has been employed/proposed as an ultrathin membrane in a myriad of microfluidic devices. Yet, an experimental investigation of eventual variations on the apparent elastic properties of a suspended graphene membrane in contact with air or water is still missing. In this work, the mechanical response of suspended monolayer graphene membranes on a microfluidic platform is investigated via scanning probe microscopy experiments. A high elastic modulus is measured for the membrane when the platform is filled with air, as expected. However, a significant apparent softening of graphene is observed when water fills the microfluidic system. Through molecular dynamics simulations and a phenomenological model, we associate such softening to a water-induced uncrumpling process of the suspended graphene membrane. This result may bring substantial modifications on the design and operation of microfluidic devices which exploit pressure application on graphene membranes.

Effect of Dialkyl Ammonium Cationic Surfactants on the Microfluidity of Membranes Containing Raft Domains.

PubMed

Uyama, Makoto; Inoue, Kaori; Kinoshita, Koichi; Miyahara, Reiji; Yokoyama, Hirokazu; Nakano, Minoru

2018-01-01

It has been reported that a lot of receptors localize in lipid raft domains and that the microfluidity of these domains regulates the activation of these receptors. In this study, we focused on the lipid raft and in order to evaluate the physicochemical effects of surfactants on microfluidity of lipid membranes, we used liposomes comprising of egg-yolk L-α-phosphatidylcholine, egg-yolk sphingomyelin, and cholesterol as a model of cell membranes containing raft domains. The microfluidity of the domains was characterized by fluorescence spectrometry using 1,6-diphenyl-1,3,5-hexatriene and 2-dimethylamino-6-lauroylnaphthalene. Among several surfactants, dialkylammonium-type cationic surfactants most efficiently increased the microfluidity. It is therefore concluded that (1) the electrostatic interaction between the cationic surfactant and eggPC/eggSM/cholesterol liposome could be important, (2) surfactants with alkyl chains more effectively inserted into membranes than those with acyl chains, and (3) cationic surfactants with lower T m values have a greater ability to increase the fluidity.

A novel mast cell co-culture microfluidic chip for the electrochemical evaluation of food allergen.

PubMed

Jiang, Hui; Jiang, Donglei; Zhu, Pei; Pi, Fuwei; Ji, Jian; Sun, Chao; Sun, Jiadi; Sun, Xiulan

2016-09-15

In this study a novel cell-to-cell electrochemical microfluidic chip was developed for qualitative and quantitative analysis of food allergen. Microfluidic cell culture, food allergen-induced cell morphological changes, and cell metabolism measurements were performed simultaneously using the aforementioned device. RBL-2H3 mast cells and ANA-1 macrophages have been used within a cell co-culture model to observe their allergic response when they are introduced to the antigen stimulus. Two cell cultivation microfluidic channels are located in the microfluidic chip, which is fabricated with four groups of gold electrodes, with an additional "capillary". In order to detect the allergic response, the cells were stimulated with dinitrophenylated bovine serum albumin (DNP-BSA) without anti-DNP IgE incubation. When exocytosis occurs, the cell-secreted inflammatory cytokines were measured by enzyme-linked immuno sorbent assay (ELISA) and cell impedance changes were detected using cell-based electrochemical assay. Results indicate that the real-time cell allergic response are accurately monitored by this electrochemical microfluidic chip, which provides a general example of rapidly prototyped low-cost biosensor technology for applications in both food allergen detection and investigation. Copyright © 2016 Elsevier B.V. All rights reserved.

Predicting the behavior of microfluidic circuits made from discrete elements

PubMed Central

Bhargava, Krisna C.; Thompson, Bryant; Iqbal, Danish; Malmstadt, Noah

2015-01-01

Microfluidic devices can be used to execute a variety of continuous flow analytical and synthetic chemistry protocols with a great degree of precision. The growing availability of additive manufacturing has enabled the design of microfluidic devices with new functionality and complexity. However, these devices are prone to larger manufacturing variation than is typical of those made with micromachining or soft lithography. In this report, we demonstrate a design-for-manufacturing workflow that addresses performance variation at the microfluidic element and circuit level, in context of mass-manufacturing and additive manufacturing. Our approach relies on discrete microfluidic elements that are characterized by their terminal hydraulic resistance and associated tolerance. Network analysis is employed to construct simple analytical design rules for model microfluidic circuits. Monte Carlo analysis is employed at both the individual element and circuit level to establish expected performance metrics for several specific circuit configurations. A protocol based on osmometry is used to experimentally probe mixing behavior in circuits in order to validate these approaches. The overall workflow is applied to two application circuits with immediate use at on the bench-top: series and parallel mixing circuits that are modularly programmable, virtually predictable, highly precise, and operable by hand. PMID:26516059

Polymer-based platform for microfluidic systems

DOEpatents

Benett, William [Livermore, CA; Krulevitch, Peter [Pleasanton, CA; Maghribi, Mariam [Livermore, CA; Hamilton, Julie [Tracy, CA; Rose, Klint [Boston, MA; Wang, Amy W [Oakland, CA

2009-10-13

A method of forming a polymer-based microfluidic system platform using network building blocks selected from a set of interconnectable network building blocks, such as wire, pins, blocks, and interconnects. The selected building blocks are interconnectably assembled and fixedly positioned in precise positions in a mold cavity of a mold frame to construct a three-dimensional model construction of a microfluidic flow path network preferably having meso-scale dimensions. A hardenable liquid, such as poly (dimethylsiloxane) is then introduced into the mold cavity and hardened to form a platform structure as well as to mold the microfluidic flow path network having channels, reservoirs and ports. Pre-fabricated elbows, T's and other joints are used to interconnect various building block elements together. After hardening the liquid the building blocks are removed from the platform structure to make available the channels, cavities and ports within the platform structure. Microdevices may be embedded within the cast polymer-based platform, or bonded to the platform structure subsequent to molding, to create an integrated microfluidic system. In this manner, the new microfluidic platform is versatile and capable of quickly generating prototype systems, and could easily be adapted to a manufacturing setting.

Construction of a microfluidic chip, using dried-down reagents, for LATE-PCR amplification and detection of single-stranded DNA.

PubMed

Jia, Yanwei; Mak, Pui-In; Massey, Conner; Martins, Rui P; Wangh, Lawrence J

2013-12-07

LATE-PCR is an advanced form of non-symmetric PCR that efficiently generates single-stranded DNA which can readily be characterized at the end of amplification by hybridization to low-temperature fluorescent probes. We demonstrate here for the first time that monoplex and duplex LATE-PCR amplification and probe target hybridization can be carried out in double layered PDMS microfluidics chips containing dried reagents. Addition of a set of reagents during dry down overcomes the common problem of single-stranded oligonucleotide binding to PDMS. These proof-of-principle results open the way to construction of inexpensive point-of-care devices that take full advantage of the analytical power of assays built using LATE-PCR and low-temperature probes.

Digital Microfluidics for Nucleic Acid Amplification

PubMed Central

Veigas, Bruno; Fortunato, Elvira; Martins, Rodrigo; Águas, Hugo; Igreja, Rui; Baptista, Pedro V.

2017-01-01

Digital Microfluidics (DMF) has emerged as a disruptive methodology for the control and manipulation of low volume droplets. In DMF, each droplet acts as a single reactor, which allows for extensive multiparallelization of biological and chemical reactions at a much smaller scale. DMF devices open entirely new and promising pathways for multiplex analysis and reaction occurring in a miniaturized format, thus allowing for healthcare decentralization from major laboratories to point-of-care with accurate, robust and inexpensive molecular diagnostics. Here, we shall focus on DMF platforms specifically designed for nucleic acid amplification, which is key for molecular diagnostics of several diseases and conditions, from pathogen identification to cancer mutations detection. Particular attention will be given to the device architecture, materials and nucleic acid amplification applications in validated settings. PMID:28672827

Generation of Customizable Micro-wavy Pattern through Grayscale Direct Image Lithography

PubMed Central

He, Ran; Wang, Shunqiang; Andrews, Geoffrey; Shi, Wentao; Liu, Yaling

2016-01-01

With the increasing amount of research work in surface studies, a more effective method of producing patterned microstructures is highly desired due to the geometric limitations and complex fabricating process of current techniques. This paper presents an efficient and cost-effective method to generate customizable micro-wavy pattern using direct image lithography. This method utilizes a grayscale Gaussian distribution effect to model inaccuracies inherent in the polymerization process, which are normally regarded as trivial matters or errors. The measured surface profiles and the mathematical prediction show a good agreement, demonstrating the ability of this method to generate wavy patterns with precisely controlled features. An accurate pattern can be generated with customizable parameters (wavelength, amplitude, wave shape, pattern profile, and overall dimension). This mask-free photolithography approach provides a rapid fabrication method that is capable of generating complex and non-uniform 3D wavy patterns with the wavelength ranging from 12 μm to 2100 μm and an amplitude-to-wavelength ratio as large as 300%. Microfluidic devices with pure wavy and wavy-herringbone patterns suitable for capture of circulating tumor cells are made as a demonstrative application. A completely customized microfluidic device with wavy patterns can be created within a few hours without access to clean room or commercial photolithography equipment. PMID:26902520

Comparison of Traditional and Open-Access Appointment Scheduling for Exponentially Distributed Service Time.

PubMed

Yan, Chongjun; Tang, Jiafu; Jiang, Bowen; Fung, Richard Y K

2015-01-01

This paper compares the performance measures of traditional appointment scheduling (AS) with those of an open-access appointment scheduling (OA-AS) system with exponentially distributed service time. A queueing model is formulated for the traditional AS system with no-show probability. The OA-AS models assume that all patients who call before the session begins will show up for the appointment on time. Two types of OA-AS systems are considered: with a same-session policy and with a same-or-next-session policy. Numerical results indicate that the superiority of OA-AS systems is not as obvious as those under deterministic scenarios. The same-session system has a threshold of relative waiting cost, after which the traditional system always has higher total costs, and the same-or-next-session system is always preferable, except when the no-show probability or the weight of patients' waiting is low. It is concluded that open-access policies can be viewed as alternative approaches to mitigate the negative effects of no-show patients.

Microfluidics-Based in Vivo Mimetic Systems for the Study of Cellular Biology

PubMed Central

2015-01-01

Conspectus The human body is a complex network of molecules, organelles, cells, tissues, and organs: an uncountable number of interactions and transformations interconnect all the system’s components. In addition to these biochemical components, biophysical components, such as pressure, flow, and morphology, and the location of all of these interactions play an important role in the human body. Technical difficulties have frequently limited researchers from observing cellular biology as it occurs within the human body, but some state-of-the-art analytical techniques have revealed distinct cellular behaviors that occur only in the context of the interactions. These types of findings have inspired bioanalytical chemists to provide new tools to better understand these cellular behaviors and interactions. What blocks us from understanding critical biological interactions in the human body? Conventional approaches are often too naïve to provide realistic data and in vivo whole animal studies give complex results that may or may not be relevant for humans. Microfluidics offers an opportunity to bridge these two extremes: while these studies will not model the complexity of the in vivo human system, they can control the complexity so researchers can examine critical factors of interest carefully and quantitatively. In addition, the use of human cells, such as cells isolated from donated blood, captures human-relevant data and limits the use of animals in research. In addition, researchers can adapt these systems easily and cost-effectively to a variety of high-end signal transduction mechanisms, facilitating high-throughput studies that are also spatially, temporally, or chemically resolved. These strengths should allow microfluidic platforms to reveal critical parameters in the human body and provide insights that will help with the translation of pharmacological advances to clinical trials. In this Account, we describe selected microfluidic innovations within the last 5 years that focus on modeling both biophysical and biochemical interactions in cellular communication, such as flow and cell–cell networks. We also describe more advanced systems that mimic higher level biological networks, such as organ on-a-chip and animal on-a-chip models. Since the first papers in the early 1990s, interest in the bioanalytical use of microfluidics has grown significantly. Advances in micro-/nanofabrication technology have allowed researchers to produce miniaturized, biocompatible assay platforms suitable for microfluidic studies in biochemistry and chemical biology. Well-designed microfluidic platforms can achieve quick, in vitro analyses on pico- and femtoliter volume samples that are temporally, spatially, and chemically resolved. In addition, controlled cell culture techniques using a microfluidic platform have produced biomimetic systems that allow researchers to replicate and monitor physiological interactions. Pioneering work has successfully created cell–fluid, cell–cell, cell–tissue, tissue–tissue, even organ-like level interfaces. Researchers have monitored cellular behaviors in these biomimetic microfluidic environments, producing validated model systems to understand human pathophysiology and to support the development of new therapeutics. PMID:24555566

Microfluidics-based in vivo mimetic systems for the study of cellular biology.

PubMed

Kim, Donghyuk; Wu, Xiaojie; Young, Ashlyn T; Haynes, Christy L

2014-04-15

The human body is a complex network of molecules, organelles, cells, tissues, and organs: an uncountable number of interactions and transformations interconnect all the system's components. In addition to these biochemical components, biophysical components, such as pressure, flow, and morphology, and the location of all of these interactions play an important role in the human body. Technical difficulties have frequently limited researchers from observing cellular biology as it occurs within the human body, but some state-of-the-art analytical techniques have revealed distinct cellular behaviors that occur only in the context of the interactions. These types of findings have inspired bioanalytical chemists to provide new tools to better understand these cellular behaviors and interactions. What blocks us from understanding critical biological interactions in the human body? Conventional approaches are often too naïve to provide realistic data and in vivo whole animal studies give complex results that may or may not be relevant for humans. Microfluidics offers an opportunity to bridge these two extremes: while these studies will not model the complexity of the in vivo human system, they can control the complexity so researchers can examine critical factors of interest carefully and quantitatively. In addition, the use of human cells, such as cells isolated from donated blood, captures human-relevant data and limits the use of animals in research. In addition, researchers can adapt these systems easily and cost-effectively to a variety of high-end signal transduction mechanisms, facilitating high-throughput studies that are also spatially, temporally, or chemically resolved. These strengths should allow microfluidic platforms to reveal critical parameters in the human body and provide insights that will help with the translation of pharmacological advances to clinical trials. In this Account, we describe selected microfluidic innovations within the last 5 years that focus on modeling both biophysical and biochemical interactions in cellular communication, such as flow and cell-cell networks. We also describe more advanced systems that mimic higher level biological networks, such as organ on-a-chip and animal on-a-chip models. Since the first papers in the early 1990s, interest in the bioanalytical use of microfluidics has grown significantly. Advances in micro-/nanofabrication technology have allowed researchers to produce miniaturized, biocompatible assay platforms suitable for microfluidic studies in biochemistry and chemical biology. Well-designed microfluidic platforms can achieve quick, in vitro analyses on pico- and femtoliter volume samples that are temporally, spatially, and chemically resolved. In addition, controlled cell culture techniques using a microfluidic platform have produced biomimetic systems that allow researchers to replicate and monitor physiological interactions. Pioneering work has successfully created cell-fluid, cell-cell, cell-tissue, tissue-tissue, even organ-like level interfaces. Researchers have monitored cellular behaviors in these biomimetic microfluidic environments, producing validated model systems to understand human pathophysiology and to support the development of new therapeutics.

50 CFR 660.313 - Open access fishery-recordkeeping and reporting.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Open access fishery-recordkeeping and... West Coast Groundfish-Open Access Fisheries § 660.313 Open access fishery—recordkeeping and reporting... to open access fisheries. (b) Declaration reports for vessels using nontrawl gear. Declaration...

50 CFR 660.313 - Open access fishery-recordkeeping and reporting.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Open access fishery-recordkeeping and... West Coast Groundfish-Open Access Fisheries § 660.313 Open access fishery—recordkeeping and reporting... to open access fisheries. (b) Declaration reports for vessels using nontrawl gear. Declaration...

50 CFR 660.313 - Open access fishery-recordkeeping and reporting.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Open access fishery-recordkeeping and... West Coast Groundfish-Open Access Fisheries § 660.313 Open access fishery—recordkeeping and reporting... to open access fisheries. (b) Declaration reports for vessels using nontrawl gear. Declaration...

50 CFR 660.313 - Open access fishery-recordkeeping and reporting.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Open access fishery-recordkeeping and... West Coast Groundfish-Open Access Fisheries § 660.313 Open access fishery—recordkeeping and reporting... to open access fisheries. (b) Declaration reports for vessels using nontrawl gear. Declaration...

50 CFR 660.313 - Open access fishery-recordkeeping and reporting.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Open access fishery-recordkeeping and... West Coast Groundfish-Open Access Fisheries § 660.313 Open access fishery—recordkeeping and reporting... to open access fisheries. (b) Declaration reports for vessels using nontrawl gear. Declaration...

Finite Element Model of Oxygen Transport for the Design of Geometrically Complex Microfluidic Devices Used in Biological Studies

PubMed Central

Fraser, Graham M.; Goldman, Daniel; Ellis, Christopher G.

2016-01-01

Red blood cells play a crucial role in the local regulation of oxygen supply in the microcirculation through the oxygen dependent release of ATP. Since red blood cells serve as an oxygen sensor for the circulatory system, the dynamics of ATP release determine the effectiveness of red blood cells to relate the oxygen levels to the vessels. Previous work has focused on the feasibility of developing a microfluidic system to measure the dynamics of ATP release. The objective was to determine if a steep oxygen gradient could be developed in the channel to cause a rapid decrease in hemoglobin oxygen saturation in order to measure the corresponding levels of ATP released from the red blood cells. In the present study, oxygen transport simulations were used to optimize the geometric design parameters for a similar system which is easier to fabricate. The system is composed of a microfluidic device stacked on top of a large, gas impermeable flow channel with a hole to allow gas exchange. The microfluidic device is fabricated using soft lithography in polydimethyl-siloxane, an oxygen permeable material. Our objective is twofold: (1) optimize the parameters of our system and (2) develop a method to assess the oxygen distribution in complex 3D microfluidic device geometries. 3D simulations of oxygen transport were performed to simulate oxygen distribution throughout the device. The simulations demonstrate that microfluidic device geometry plays a critical role in molecule exchange, for instance, changing the orientation of the short wide microfluidic channel results in a 97.17% increase in oxygen exchange. Since microfluidic devices have become a more prominent tool in biological studies, understanding the transport of oxygen and other biological molecules in microfluidic devices is critical for maintaining a physiologically relevant environment. We have also demonstrated a method to assess oxygen levels in geometrically complex microfluidic devices. PMID:27829071

Finite Element Model of Oxygen Transport for the Design of Geometrically Complex Microfluidic Devices Used in Biological Studies.

PubMed

Sové, Richard J; Fraser, Graham M; Goldman, Daniel; Ellis, Christopher G

2016-01-01

Red blood cells play a crucial role in the local regulation of oxygen supply in the microcirculation through the oxygen dependent release of ATP. Since red blood cells serve as an oxygen sensor for the circulatory system, the dynamics of ATP release determine the effectiveness of red blood cells to relate the oxygen levels to the vessels. Previous work has focused on the feasibility of developing a microfluidic system to measure the dynamics of ATP release. The objective was to determine if a steep oxygen gradient could be developed in the channel to cause a rapid decrease in hemoglobin oxygen saturation in order to measure the corresponding levels of ATP released from the red blood cells. In the present study, oxygen transport simulations were used to optimize the geometric design parameters for a similar system which is easier to fabricate. The system is composed of a microfluidic device stacked on top of a large, gas impermeable flow channel with a hole to allow gas exchange. The microfluidic device is fabricated using soft lithography in polydimethyl-siloxane, an oxygen permeable material. Our objective is twofold: (1) optimize the parameters of our system and (2) develop a method to assess the oxygen distribution in complex 3D microfluidic device geometries. 3D simulations of oxygen transport were performed to simulate oxygen distribution throughout the device. The simulations demonstrate that microfluidic device geometry plays a critical role in molecule exchange, for instance, changing the orientation of the short wide microfluidic channel results in a 97.17% increase in oxygen exchange. Since microfluidic devices have become a more prominent tool in biological studies, understanding the transport of oxygen and other biological molecules in microfluidic devices is critical for maintaining a physiologically relevant environment. We have also demonstrated a method to assess oxygen levels in geometrically complex microfluidic devices.

Getting started with open-hardware: development and control of microfluidic devices.

PubMed

da Costa, Eric Tavares; Mora, Maria F; Willis, Peter A; do Lago, Claudimir L; Jiao, Hong; Garcia, Carlos D

2014-08-01

Understanding basic concepts of electronics and computer programming allows researchers to get the most out of the equipment found in their laboratories. Although a number of platforms have been specifically designed for the general public and are supported by a vast array of on-line tutorials, this subject is not normally included in university chemistry curricula. Aiming to provide the basic concepts of hardware and software, this article is focused on the design and use of a simple module to control a series of PDMS-based valves. The module is based on a low-cost microprocessor (Teensy) and open-source software (Arduino). The microvalves were fabricated using thin sheets of PDMS and patterned using CO2 laser engraving, providing a simple and efficient way to fabricate devices without the traditional photolithographic process or facilities. Synchronization of valve control enabled the development of two simple devices to perform injection (1.6 ± 0.4 μL/stroke) and mixing of different solutions. Furthermore, a practical demonstration of the utility of this system for microscale chemical sample handling and analysis was achieved performing an on-chip acid-base titration, followed by conductivity detection with an open-source low-cost detection system. Overall, the system provided a very reproducible (98%) platform to perform fluid delivery at the microfluidic scale. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Morphological study of lipid vesicles in presence of amphotericin B via modification of the microfluidic CellASIC platform and LED illumination microscopy

NASA Astrophysics Data System (ADS)

Genova, J.; Decheva-Zarkova, M.; Pavlič, J. I.

2016-02-01

Giant lipid vesicles (liposomes) are the simplest model of the biological cell and can be easily formed from natural or synthetic lipid species with controlled composition and properties. This is the reason why they are the preferred objects for various scientific investigations. Amphotericin B (AmB) is a membrane active drug, used for treatment of systemic fungal infections. In this work we studied the morphological behavior of giant SOPC vesicles in asymmetrical presence of amphotericin B antibiotic in the vicinity of the lipid membrane. The visualization of the vesicles was carried out via inverted phase contrast microscopy. The illumination source was modified in a way that tungsten light bulb was replaced by 10 W white LED chip. All the experiments were performed using CellASIC ONIX Microfluidic Platform. The setup has been modified thus opening new opportunities for a variety of experimental realizations. The performed morphological studies showed strong and irreversible effect on the vesicle shape at the presence of amphotericin B in concentration 10-5 g/l in the outer for the liposome's membrane solution. At concentration 10-3 g/l AmB the effect was less visible and in 15-20 minutes the vesicles regained its initial spherical shape.

Aptamer entrapment in microfluidic channel using one-step sol-gel process, in view of the integration of a new selective extraction phase for lab-on-a-chip.

PubMed

Perréard, Camille; d'Orlyé, Fanny; Griveau, Sophie; Liu, Baohong; Bedioui, Fethi; Varenne, Anne

2017-10-01

There is a great demand for integrating sample treatment into μTASs. In this context, we developed a new sol-gel phase for extraction of trace compounds in complex matrices. For this purpose, the incorporation of aptamers in silica-based gel within PDMS/glass microfluidic channels was performed for the first time by a one-step sol-gel process. The effective gel attachment onto microchannel walls and aptamer incorporation in the polymerized gel were evaluated using fluorescence microscopy. A good gel stability and aptamer incorporation inside the microchannel was demonstrated upon rinsing and over storage time. The ability of gel-encapsulated aptamers to interact with its specific target (either sulforhodamine B as model fluorescent target, or diclofenac, a pain killer drug) was assessed too. The binding capacity of entrapped aptamers was quantified (in the micromolar range) and the selectivity of the interaction was evidenced. Preservation of aptamers binding affinity to target molecules was therefore demonstrated. Dissociation constant of the aptamer-target complex and interaction selectivity were evaluated similar to those in bulk solution. This opens the way to new selective on-chip SPE techniques for sample pretreatment. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optimized Mixing in Microchannels with Integrated Microactuators

NASA Astrophysics Data System (ADS)

Folk, Christopher Richard

Microscale valves and pumps have been designed and fabricated for integration into a microfluidic circuit. Furthermore, a micromixer for this circuit has been designed and optimized. N-isopropylacrylamide (NIPA) gels have been fabricated and actuated directly with heat and indirectly by laser. A new method for photopatterning these gels based on photoinitiation has been used to fabricate hydrogel valves down to 50 mum in diameter. Hydrogel valves have been fabricated in situ in a microfluidic network. The valves open in 27 seconds and close via diffusion of water into the gel in 128 seconds, which is faster than other optically-driven polymers used for large displacements. In this research, azobis-isobutyronitrile (AIBN) is incorporated into a variety of polydimethylsiloxane (PDMS) pump chambers. The AIBN is heated via integrated resistive heaters and decomposes to release nitrogen gas. The nitrogen gas provides impulse power to a PDMS diaphragm to displace the fluid. The pump devices have been built and characterized. Lastly, in this work, we describe the use of combined fluid dynamic and diffusion modeling to simulate a micromixer based on the elements above. The micromixer is optimized via Design of Experiments to produce an optimized geometry for mixing. The optimization is validated via comparison to previous work through the Strouhal number.

National Utility Rate Database: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ong, S.; McKeel, R.

2012-08-01

When modeling solar energy technologies and other distributed energy systems, using high-quality expansive electricity rates is essential. The National Renewable Energy Laboratory (NREL) developed a utility rate platform for entering, storing, updating, and accessing a large collection of utility rates from around the United States. This utility rate platform lives on the Open Energy Information (OpenEI) website, OpenEI.org, allowing the data to be programmatically accessed from a web browser, using an application programming interface (API). The semantic-based utility rate platform currently has record of 1,885 utility rates and covers over 85% of the electricity consumption in the United States.

50 CFR 660.330 - Open access fishery-management measures.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Open access fishery-management measures... West Coast Groundfish-Open Access Fisheries § 660.330 Open access fishery—management measures. (a) General. Groundfish species taken in open access fisheries will be managed with cumulative trip limits...

50 CFR 660.330 - Open access fishery-management measures.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Open access fishery-management measures... West Coast Groundfish-Open Access Fisheries § 660.330 Open access fishery—management measures. (a) General. Groundfish species taken in open access fisheries will be managed with cumulative trip limits...

50 CFR 660.330 - Open access fishery-management measures.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Open access fishery-management measures... West Coast Groundfish-Open Access Fisheries § 660.330 Open access fishery—management measures. (a) General. Groundfish species taken in open access fisheries will be managed with cumulative trip limits...

50 CFR 660.320 - Open access fishery-crossover provisions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Open access fishery-crossover provisions... West Coast Groundfish-Open Access Fisheries § 660.320 Open access fishery—crossover provisions. (a) Operating in both limited entry and open access fisheries. See provisions at § 660.60, subpart C. (b...

50 CFR 660.320 - Open access fishery-crossover provisions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Open access fishery-crossover provisions... West Coast Groundfish-Open Access Fisheries § 660.320 Open access fishery—crossover provisions. (a) Operating in both limited entry and open access fisheries. See provisions at § 660.60, subpart C. (b...

50 CFR 660.312 - Open access fishery-prohibitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Open access fishery-prohibitions. 660.312... Groundfish-Open Access Fisheries § 660.312 Open access fishery—prohibitions. General groundfish prohibitions..., possess, or land groundfish in excess of the landing limit for the open access fishery without having a...

50 CFR 660.330 - Open access fishery-management measures.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Open access fishery-management measures... West Coast Groundfish-Open Access Fisheries § 660.330 Open access fishery—management measures. (a) General. Groundfish species taken in open access fisheries will be managed with cumulative trip limits...

50 CFR 660.312 - Open access fishery-prohibitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Open access fishery-prohibitions. 660.312... Groundfish-Open Access Fisheries § 660.312 Open access fishery—prohibitions. General groundfish prohibitions..., possess, or land groundfish in excess of the landing limit for the open access fishery without having a...

50 CFR 660.312 - Open access fishery-prohibitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Open access fishery-prohibitions. 660.312... Groundfish-Open Access Fisheries § 660.312 Open access fishery—prohibitions. General groundfish prohibitions..., possess, or land groundfish in excess of the landing limit for the open access fishery without having a...

50 CFR 660.312 - Open access fishery-prohibitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Open access fishery-prohibitions. 660.312... Groundfish-Open Access Fisheries § 660.312 Open access fishery—prohibitions. General groundfish prohibitions..., possess, or land groundfish in excess of the landing limit for the open access fishery without having a...

50 CFR 660.312 - Open access fishery-prohibitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Open access fishery-prohibitions. 660.312... Groundfish-Open Access Fisheries § 660.312 Open access fishery—prohibitions. General groundfish prohibitions..., possess, or land groundfish in excess of the landing limit for the open access fishery without having a...

50 CFR 660.330 - Open access fishery-management measures.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Open access fishery-management measures... West Coast Groundfish-Open Access Fisheries § 660.330 Open access fishery—management measures. (a) General. Groundfish species taken in open access fisheries will be managed with cumulative trip limits...

Medical education and information literacy in the era of open access.

PubMed

Brower, Stewart M

2010-01-01

The Open Access movement in scholarly communications poses new issues and concerns for medical education in general and information literacy education specifically. For medical educators, Open Access can affect the availability of new information, instructional materials, and scholarship in medical education. For students, Open Access materials continue to be available to them post-graduation, regardless of affiliation. Libraries and information literacy librarians are challenged in their responses to the Open Access publishing movement in how best to support Open Access endeavors within their own institutions, and how best to educate their user base about Open Access in general.

Rapid concentration of deoxyribonucleic acid via Joule heating induced temperature gradient focusing in poly-dimethylsiloxane microfluidic channel.

PubMed

Ge, Zhengwei; Wang, Wei; Yang, Chun

2015-02-09

This paper reports rapid microfluidic electrokinetic concentration of deoxyribonucleic acid (DNA) with the Joule heating induced temperature gradient focusing (TGF) by using our proposed combined AC and DC electric field technique. A peak of 480-fold concentration enhancement of DNA sample is achieved within 40s in a simple poly-dimethylsiloxane (PDMS) microfluidic channel of a sudden expansion in cross-section. Compared to a sole DC field, the introduction of an AC field can reduce DC field induced back-pressure and produce sufficient Joule heating effects, resulting in higher concentration enhancement. Within such microfluidic channel structure, negative charged DNA analytes can be concentrated at a location where the DNA electrophoretic motion is balanced with the bulk flow driven by DC electroosmosis under an appropriate temperature gradient field. A numerical model accounting for a combined AC and DC field and back-pressure driven flow effects is developed to describe the complex Joule heating induced TGF processes. The experimental observation of DNA concentration phenomena can be explained by the numerical model. Copyright © 2014 Elsevier B.V. All rights reserved.

Application of microfluidic technologies to human assisted reproduction.

PubMed

Smith, Gary D; Takayama, Shuichi

2017-04-01

Microfluidics can be considered both a science and a technology. It is defined as the study of fluid behavior at a sub-microliter level and the investigation into its application to cell biology, chemistry, genetics, molecular biology and medicine. There are at least two characteristics of microfluidics, mechanical and biochemical, which can be influential in the field of mammalian gamete and preimplantation embryo biology. These microfluidic characteristics can assist in basic biological studies on sperm, oocyte and preimplantation embryo structure, function and environment. The mechanical and biochemical characteristics of microfluidics may also have practical and/or technical application(s) to assisted reproductive technologies (ART) in rodents, domestic species, endangered species and humans. This review will consider data in mammals, and when available humans, addressing the potential application(s) of microfluidics to assisted reproduction. There are numerous sequential steps in the clinical assisted reproductive laboratory process that work, yet could be improved. Cause and effect relations of procedural inefficiencies can be difficult to identify and/or remedy. Data will be presented that consider microfluidic applications to sperm isolation, oocyte cumulus complex isolation, oocyte denuding, oocyte mechanical manipulation, conventional insemination, intracytoplasmic sperm injection, embryo culture, embryo analysis and oocyte and embryo cryopreservation. While these studies have progressed in animal models, data with human gametes and embryos are significantly lacking. These data from clinical trials are requisite for making future evidence-based decisions regarding the application of microfluidics in human ART. © The Author 2017. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved.For Permissions, please email: journals.permissions@oup.com.

Nonlinear pressure-flow relationships for passive microfluidic valves.

PubMed

Seker, Erkin; Leslie, Daniel C; Haj-Hariri, Hossein; Landers, James P; Utz, Marcel; Begley, Matthew R

2009-09-21

An analytical solution is presented for the nonlinear pressure-flow relationship of deformable passive valves, which are formed by bonding a deformable film over etched channels separated by a weir. A fluidic pathway connecting the channels is opened when the upstream pressure creates a tunnel along a predefined narrow strip where the film is not bonded to the weir. When the width of the strip is comparable to the inlet channel width, the predicted closed-form pressure-flow rate relationship is in excellent agreement with experiments, which determine pressures by measuring film deflections for prescribed flow rates. The validated closed-form models involve no fitting parameters, and provide the foundation to design passive diodes with specific nonlinear pressure-flow characteristics.

Turning the Page: Advancing Paper-Based Microfluidics for Broad Diagnostic Application.

PubMed

Gong, Max M; Sinton, David

2017-06-28

Infectious diseases are a major global health issue. Diagnosis is a critical first step in effectively managing their spread. Paper-based microfluidic diagnostics first emerged in 2007 as a low-cost alternative to conventional laboratory testing, with the goal of improving accessibility to medical diagnostics in developing countries. In this review, we examine the advances in paper-based microfluidic diagnostics for medical diagnosis in the context of global health from 2007 to 2016. The theory of fluid transport in paper is first presented. The next section examines the strategies that have been employed to control fluid and analyte transport in paper-based assays. Tasks such as mixing, timing, and sequential fluid delivery have been achieved in paper and have enabled analytical capabilities comparable to those of conventional laboratory methods. The following section examines paper-based sample processing and analysis. The most impactful advancement here has been the translation of nucleic acid analysis to a paper-based format. Smartphone-based analysis is another exciting development with potential for wide dissemination. The last core section of the review highlights emerging health applications, such as male fertility testing and wearable diagnostics. We conclude the review with the future outlook, remaining challenges, and emerging opportunities.

Publishing in Open Access Education Journals: The Authors' Perspectives

ERIC Educational Resources Information Center

Coonin, Bryna; Younce, Leigh M.

2010-01-01

Open access publishing is now an accepted method of scholarly communication. However, the greatest traction for open access publishing thus far has been in the sciences. Penetration of open access publishing has been much slower among the social sciences. This study surveys 309 authors from recent issues of open access journals in education to…

50 CFR 660.311 - Open access fishery-definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Open access fishery-definitions. 660.311... Groundfish-Open Access Fisheries § 660.311 Open access fishery—definitions. General definitions for the... specific to the open access fishery covered in this subpart and are in addition to those specified at § 660...

50 CFR 660.311 - Open access fishery-definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Open access fishery-definitions. 660.311... Groundfish-Open Access Fisheries § 660.311 Open access fishery—definitions. General definitions for the... specific to the open access fishery covered in this subpart and are in addition to those specified at § 660...

50 CFR 660.320 - Open access fishery-crossover provisions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Open access fishery-crossover provisions... West Coast Groundfish-Open Access Fisheries § 660.320 Open access fishery—crossover provisions. The crossover provisions listed at § 660.60(h)(7), apply to vessels fishing in the open access fishery. [76 FR...

50 CFR 660.320 - Open access fishery-crossover provisions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Open access fishery-crossover provisions... West Coast Groundfish-Open Access Fisheries § 660.320 Open access fishery—crossover provisions. The crossover provisions listed at § 660.60(h)(7), apply to vessels fishing in the open access fishery. [76 FR...

50 CFR 660.319 - Open access fishery gear identification and marking.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Open access fishery gear identification... COAST STATES West Coast Groundfish-Open Access Fisheries § 660.319 Open access fishery gear identification and marking. (a) Gear identification. (1) Open access fixed gear (longline, trap or pot, set net...

50 CFR 660.311 - Open access fishery-definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Open access fishery-definitions. 660.311... Groundfish-Open Access Fisheries § 660.311 Open access fishery—definitions. General definitions for the... specific to the open access fishery covered in this subpart and are in addition to those specified at § 660...

50 CFR 660.320 - Open access fishery-crossover provisions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Open access fishery-crossover provisions... West Coast Groundfish-Open Access Fisheries § 660.320 Open access fishery—crossover provisions. The crossover provisions listed at § 660.60(h)(7), apply to vessels fishing in the open access fishery. [76 FR...

50 CFR 660.311 - Open access fishery-definitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Open access fishery-definitions. 660.311... Groundfish-Open Access Fisheries § 660.311 Open access fishery—definitions. General definitions for the... specific to the open access fishery covered in this subpart and are in addition to those specified at § 660...

50 CFR 660.311 - Open access fishery-definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Open access fishery-definitions. 660.311... Groundfish-Open Access Fisheries § 660.311 Open access fishery—definitions. General definitions for the... specific to the open access fishery covered in this subpart and are in addition to those specified at § 660...

Education Scholars' Perceptions and Practices toward Open Access Publishing

ERIC Educational Resources Information Center

Ellingford, Lori Michelle

2012-01-01

Although open access publishing has been available since 1998, we know little regarding scholars' perceptions and practices toward publishing in open access outlets, especially in the social science community. Open access publishing has been slow to penetrate the field of education, yet the potential impact of open access could make this…

Open Access, Open Source and Digital Libraries: A Current Trend in University Libraries around the World

ERIC Educational Resources Information Center

Krishnamurthy, M.

2008-01-01

Purpose: The purpose of this paper is to describe the open access and open source movement in the digital library world. Design/methodology/approach: A review of key developments in the open access and open source movement is provided. Findings: Open source software and open access to research findings are of great use to scholars in developing…

Microfluidics to Mimic Blood Flow in Health and Disease

NASA Astrophysics Data System (ADS)

Sebastian, Bernhard; Dittrich, Petra S.

2018-01-01

Throughout history, capillary systems have aided the establishment of the fundamental laws of blood flow and its non-Newtonian properties. The advent of microfluidics technology in the 1990s propelled the development of highly integrated lab-on-a-chip platforms that allow highly accurate replication of vascular systems' dimensions, mechanical properties, and biological complexity. Applications include the detection of pathological changes to red blood cells, white blood cells, and platelets at unparalleled sensitivity and the efficacy assessment of drug treatment. Recent efforts have aimed at the development of microfluidics-based tests usable in a clinial environment or the replication of more complex diseases such as thrombosis. These microfluidic disease models enable the study of onset and progression of disease as well as the identification of key players and risk factors, which have led to a spectrum of clinically relevant findings.

Theory of a microfluidic serial dilution bioreactor for growth of planktonic and biofilm populations.

PubMed

Hsu, Sze-Bi; Yang, Ya-Tang

2016-04-01

We present the theory of a microfluidic bioreactor with a two-compartment growth chamber and periodic serial dilution. In the model, coexisting planktonic and biofilm populations exchange by adsorption and detachment. The criteria for coexistence and global extinction are determined by stability analysis of the global extinction state. Stability analysis yields the operating diagram in terms of the dilution and removal ratios, constrained by the plumbing action of the bioreactor. The special case of equal uptake function and logistic growth is analytically solved and explicit growth curves are plotted. The presented theory is applicable to generic microfluidic bioreactors with discrete growth chambers and periodic dilution at discrete time points. Therefore, the theory is expected to assist the design of microfluidic devices for investigating microbial competition and microbial biofilm growth under serial dilution conditions.

Electromechanical model to predict the movability of liquids in an electrowetting-on-dielectric microfluidic device

NASA Astrophysics Data System (ADS)

Torabinia, Matin; Farzbod, Ali; Moon, Hyejin

2018-04-01

In electrowetting-on-dielectric (EWOD) microfluidics, a motion of a fluid is created by a voltage applied to the fluid/surface interface. Water and aqueous solutions are the most frequently used fluids in EWOD devices. In order for EWOD microfluidics to be a versatile platform for various applications, however, movability of different types of fluids other than aqueous solutions should be understood. An electromechanical model using a simple RC circuit has been used to predict the mechanical force exerted on a liquid droplet upon voltage application. In this present study, two important features missed in previous works are addressed. Energy dissipation by contact line friction is considered in the new model as the form of resistor. The phase angle is taken into account in the analysis of the AC circuit. The new electromechanical model and computation results are validated with experimental measurements of forces on two different liquids. The model is then used to explain influences of contact angle hysteresis, surface tension, conductivity, and dielectric constant of fluids to the mechanical force on a liquid droplet.

A microfluidic multi-injector for gradient generation.

PubMed

Chung, Bong Geun; Lin, Francis; Jeon, Noo Li

2006-06-01

This paper describes a microfluidic multi-injector (MMI) that can generate temporal and spatial concentration gradients of soluble molecules. Compared to conventional glass micropipette-based methods that generate a single gradient, the MMI exploits microfluidic integration and actuation of multiple pulsatile injectors to generate arbitrary overlapping gradients that have not previously been possible. The MMI device is fabricated in poly(dimethylsiloxane) (PDMS) using multi-layer soft lithography and consists of fluidic channels and control channels with pneumatically actuated on-chip barrier valves. Repetitive actuation of on-chip valves control pulsatile release of solution that establishes microscopic chemical gradients around the orifice. The volume of solution released per actuation cycle ranged from 30 picolitres to several hundred picolitres and increased linearly with the duration of valve opening. The shape of the measured gradient profile agreed closely with the simulated diffusion profile from a point source. Steady state gradient profiles could be attained within 10 minutes, or less with an optimized pulse sequence. Overlapping gradients from 2 injectors were generated and characterized to highlight the advantages of MMI over conventional micropipette assays. The MMI platform should be useful for a wide range of basic and applied studies on chemotaxis and axon guidance.

A microfluidic device for open loop stripping of volatile organic compounds.

PubMed

Cvetković, Benjamin Z; Dittrich, Petra S

2013-03-01

The detection of volatile organic compounds is of great importance for assessing the quality of water. In this contribution, we describe a miniaturized stripping device that allows fast online detection of organic solvents in water. The core component is a glass microfluidic chip that facilitates the creation of an annular-flowing stream of water and nitrogen gas. Volatile compounds are transferred efficiently from the water into the gas phase along the microfluidic pathway at room temperature within less than 5 s. Before exiting the microchip, the liquid phase is separated from the enriched gas phase by incorporating side capillaries through which the hydrophilic water phase is withdrawn. The gas phase is conveniently collected at the outlet reservoir by tubing. Finally, a semiconductor gas sensor analyzes the concentration of (volatile) organic compounds in the nitrogen gas. The operation and use of the stripping device is demonstrated for the organic solvents THF, 1-propanol, toluene, ethylbenzene, benzaldehyde, and methanol. The mobile, inexpensive, and continuously operating system with liquid flow rates in the low range of microliters per minute can be connected to other detectors or implemented in chemical production line for process control.

A multiplexed microfluidic system for evaluation of dynamics of immune-tumor interactions.

PubMed

Moore, N; Doty, D; Zielstorff, M; Kariv, I; Moy, L Y; Gimbel, A; Chevillet, J R; Lowry, N; Santos, J; Mott, V; Kratchman, L; Lau, T; Addona, G; Chen, H; Borenstein, J T

2018-05-25

Recapitulation of the tumor microenvironment is critical for probing mechanisms involved in cancer, and for evaluating the tumor-killing potential of chemotherapeutic agents, targeted therapies and immunotherapies. Microfluidic devices have emerged as valuable tools for both mechanistic studies and for preclinical evaluation of therapeutic agents, due to their ability to precisely control drug concentrations and gradients of oxygen and other species in a scalable and potentially high throughput manner. Most existing in vitro microfluidic cancer models are comprised of cultured cancer cells embedded in a physiologically relevant matrix, collocated with vascular-like structures. However, the recent emergence of immune checkpoint inhibitors (ICI) as a powerful therapeutic modality against many cancers has created a need for preclinical in vitro models that accommodate interactions between tumors and immune cells, particularly for assessment of unprocessed tumor fragments harvested directly from patient biopsies. Here we report on a microfluidic model, termed EVIDENT (ex vivo immuno-oncology dynamic environment for tumor biopsies), that accommodates up to 12 separate tumor biopsy fragments interacting with flowing tumor-infiltrating lymphocytes (TILs) in a dynamic microenvironment. Flow control is achieved with a single pump in a simple and scalable configuration, and the entire system is constructed using low-sorption materials, addressing two principal concerns with existing microfluidic cancer models. The system sustains tumor fragments for multiple days, and permits real-time, high-resolution imaging of the interaction between autologous TILs and tumor fragments, enabling mapping of TIL-mediated tumor killing and testing of various ICI treatments versus tumor response. Custom image analytic algorithms based on machine learning reported here provide automated and quantitative assessment of experimental results. Initial studies indicate that the system is capable of quantifying temporal levels of TIL infiltration and tumor death, and that the EVIDENT model mimics the known in vivo tumor response to anti-PD-1 ICI treatment of flowing TILs relative to isotype control treatments for syngeneic mouse MC38 tumors.

What Are the Factors Influencing Implementation of Advanced Access in Family Medicine Units? A Cross-Case Comparison of Four Early Adopters in Quebec

PubMed Central

Touati, Nassera; Maillet, Lara; Gaboury, Isabelle

2017-01-01

Introduction Advanced access is an organizational model that has shown promise in improving timely access to primary care. In Quebec, it has recently been introduced in several family medicine units (FMUs) with a teaching mission. The objectives of this paper are to analyze the principles of advanced access implemented in FMUs and to identify which factors influenced their implementation. Methods A multiple case study of four purposefully selected FMUs was conducted. Data included document analysis and 40 semistructured interviews with health professionals and staff. Cross-case comparison and thematic analysis were performed. Results Three out of four FMUs implemented the key principles of advanced access at various levels. One scheduling pattern was observed: 90% of open appointment slots over three- to four-week periods and 10% of prebooked appointments. Structural and organizational factors facilitated the implementation: training of staff to support change, collective leadership, and openness to change. Conversely, family physicians practicing in multiple clinical settings, lack of team resources, turnover of clerical staff, rotation of medical residents, and management capacity were reported as major barriers to implementing the model. Conclusion Our results call for multilevel implementation strategies to improve the design of the advanced access model in academic teaching settings. PMID:28775899

Autonomous Control of Fluids in a Wide Surface Tension Range in Microfluidics.

PubMed

Ge, Peng; Wang, Shuli; Liu, Yongshun; Liu, Wendong; Yu, Nianzuo; Zhang, Jianglei; Shen, Huaizhong; Zhang, Junhu; Yang, Bai

2017-07-25

In this paper, we report the preparation of anisotropic wetting surfaces that could control various wetting behaviors of liquids in a wide surface tension range (from water to oil), which could be employed as a platform for controlling the flow of liquids in microfluidics (MFs). The anisotropic wetting surfaces are chemistry-asymmetric "Janus" silicon cylinder arrays, which are fabricated via selecting and regulating the functional groups on the surface of each cylinder unit. Liquids (in a wide surface tension range) wet in a unidirectional manner along the direction that was modified by the group with large surface energy. Through introducing the Janus structure into a T-shaped pattern and integrating it with an identical T-shaped poly(dimethylsiloxane) microchannel, the as-prepared chips can be utilized to perform as a surface tension admeasuring apparatus or a one-way valve for liquids in a wide surface tension range, even oil. Furthermore, because of the excellent ability in controlling the flowing behavior of liquids in a wide surface tension range in an open system or a microchannel, the anisotropic wetting surfaces are potential candidates to be applied both in open MFs and conventional MFs, which would broaden the application fields of MFs.

Microfluidic-Mass Spectrometry Interfaces for Translational Proteomics.

PubMed

Pedde, R Daniel; Li, Huiyan; Borchers, Christoph H; Akbari, Mohsen

2017-10-01

Interfacing mass spectrometry (MS) with microfluidic chips (μchip-MS) holds considerable potential to transform a clinician's toolbox, providing translatable methods for the early detection, diagnosis, monitoring, and treatment of noncommunicable diseases by streamlining and integrating laborious sample preparation workflows on high-throughput, user-friendly platforms. Overcoming the limitations of competitive immunoassays - currently the gold standard in clinical proteomics - μchip-MS can provide unprecedented access to complex proteomic assays having high sensitivity and specificity, but without the labor, costs, and complexities associated with conventional MS sample processing. This review surveys recent μchip-MS systems for clinical applications and examines their emerging role in streamlining the development and translation of MS-based proteomic assays by alleviating many of the challenges that currently inhibit widespread clinical adoption. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Isolation of breast cancer and gastric cancer circulating tumor cells by use of an anti HER2-based microfluidic device.

PubMed

Galletti, Giuseppe; Sung, Matthew S; Vahdat, Linda T; Shah, Manish A; Santana, Steven M; Altavilla, Giuseppe; Kirby, Brian J; Giannakakou, Paraskevi

2014-01-07

Circulating tumor cells (CTCs) have emerged as a reliable source of tumor cells, and their concentration has prognostic implications. CTC capture offers real-time access to cancer tissue without the need of an invasive biopsy, while their phenotypic and molecular interrogation can provide insight into the biological changes of the tumor that occur during treatment. The majority of the CTC capture methods are based on EpCAM expression as a surface marker of tumor-derived cells. However, EpCAM protein expression levels can be significantly down regulated during cancer progression as a consequence of the process of epithelial to mesenchymal transition. In this paper, we describe a novel HER2 (Human Epidermal Receptor 2)-based microfluidic device for the isolation of CTCs from peripheral blood of patients with HER2-expressing solid tumors. We selected HER2 as an alternative to EpCAM as the receptor is biologically and therapeutically relevant in several solid tumors, like breast cancer (BC), where it is overexpressed in 30% of the patients and expressed in 90%, and gastric cancer (GC), in which HER2 presence is identified in more than 60% of the cases. We tested the performance of various anti HER2 antibodies in a panel of nine different BC cell lines with varying HER2 protein expression levels, using immunoblotting, confocal microscopy, live cells imaging and flow cytometry analyses. The antibody associated with the highest capture efficiency and sensitivity for HER2 expressing cells on the microfluidic device was the one that performed best in live cells imaging and flow cytometry assays as opposed to the fixed cell analyses, suggesting that recognition of the native conformation of the HER2 extracellular epitope on living cells was essential for specificity and sensitivity of CTC capture. Next, we tested the performance of the HER2 microfluidic device using blood from metastatic breast and gastric cancer patients. The HER2 microfluidic device exhibited CTC capture in 9/9 blood samples. Thus, the described HER2-based microfluidic device can be considered as a valid clinically relevant method for CTC capture in HER2 expressing solid cancers.

Microfluidics in the Undergraduate Laboratory: Device Fabrication and an Experiment to Mimic Intravascular Gas Embolism

ERIC Educational Resources Information Center

Jablonski, Erin L.; Vogel, Brandon M.; Cavanagh, Daniel P.; Beers, Kathryn L.

2010-01-01

A method to fabricate microfluidic devices and an experimental protocol to model intravascular gas embolism for undergraduate laboratories are presented. The fabrication process details how to produce masters on glass slides; these masters serve as molds to pattern channels in an elastomeric polymer that can be adhered to a substrate, resulting in…

Leveraging Open Standards and Technologies to Enhance Community Access to Earth Science Lidar Data

NASA Astrophysics Data System (ADS)

Crosby, C. J.; Nandigam, V.; Krishnan, S.; Cowart, C.; Baru, C.; Arrowsmith, R.

2011-12-01

Lidar (Light Detection and Ranging) data, collected from space, airborne and terrestrial platforms, have emerged as an invaluable tool for a variety of Earth science applications ranging from ice sheet monitoring to modeling of earth surface processes. However, lidar present a unique suite of challenges from the perspective of building cyberinfrastructure systems that enable the scientific community to access these valuable research datasets. Lidar data are typically characterized by millions to billions of individual measurements of x,y,z position plus attributes; these "raw" data are also often accompanied by derived raster products and are frequently terabytes in size. As a relatively new and rapidly evolving data collection technology, relevant open data standards and software projects are immature compared to those for other remote sensing platforms. The NSF-funded OpenTopography Facility project has developed an online lidar data access and processing system that co-locates data with on-demand processing tools to enable users to access both raw point cloud data as well as custom derived products and visualizations. OpenTopography is built on a Service Oriented Architecture (SOA) in which applications and data resources are deployed as standards compliant (XML and SOAP) Web services with the open source Opal Toolkit. To develop the underlying applications for data access, filtering and conversion, and various processing tasks, OpenTopography has heavily leveraged existing open source software efforts for both lidar and raster data. Operating on the de facto LAS binary point cloud format (maintained by ASPRS), open source libLAS and LASlib libraries provide OpenTopography data ingestion, query and translation capabilities. Similarly, raster data manipulation is performed through a suite of services built on the Geospatial Data Abstraction Library (GDAL). OpenTopography has also developed our own algorithm for high-performance gridding of lidar point cloud data, Points2Grid, and have released the code as an open source project. An emerging conversation that the lidar community and OpenTopography are actively engaged in is the need for open, community supported standards and metadata for both full waveform and terrestrial (waveform and discrete return) lidar data. Further, given the immature nature of many lidar data archives and limited online access to public domain data, there is an opportunity to develop interoperable data catalogs based on an open standard such as the OGC CSW specification to facilitate discovery and access to Earth science oriented lidar data.

Open access for operational research publications from low- and middle-income countries: who pays?

PubMed Central

Kumar, A. M. V.; Reid, A. J.; Van den Bergh, R.; Isaakidis, P.; Draguez, B.; Delaunois, P.; Nagaraja, S. B.; Ramsay, A.; Reeder, J. C.; Denisiuk, O.; Ali, E.; Khogali, M.; Hinderaker, S. G.; Kosgei, R. J.; van Griensven, J.; Quaglio, G. L.; Maher, D.; Billo, N. E.; Terry, R. F.; Harries, A. D.

2014-01-01

Open-access journal publications aim to ensure that new knowledge is widely disseminated and made freely accessible in a timely manner so that it can be used to improve people's health, particularly those in low- and middle-income countries. In this paper, we briefly explain the differences between closed- and open-access journals, including the evolving idea of the ‘open-access spectrum’. We highlight the potential benefits of supporting open access for operational research, and discuss the conundrum and ways forward as regards who pays for open access. PMID:26400799

The pumping lid: investigating multi-material 3D printing for equipment-free, programmable generation of positive and negative pressures for microfluidic applications.

PubMed

Begolo, Stefano; Zhukov, Dmitriy V; Selck, David A; Li, Liang; Ismagilov, Rustem F

2014-12-21

Equipment-free pumping is a challenging problem and an active area of research in microfluidics, with applications for both laboratory and limited-resource settings. This paper describes the pumping lid method, a strategy to achieve equipment-free pumping by controlled generation of pressure. Pressure was generated using portable, lightweight, and disposable parts that can be integrated with existing microfluidic devices to simplify workflow and eliminate the need for pumping equipment. The development of this method was enabled by multi-material 3D printing, which allows fast prototyping, including composite parts that combine materials with different mechanical properties (e.g. both rigid and elastic materials in the same part). The first type of pumping lid we describe was used to produce predictable positive or negative pressures via controlled compression or expansion of gases. A model was developed to describe the pressures and flow rates generated with this approach and it was validated experimentally. Pressures were pre-programmed by the geometry of the parts and could be tuned further even while the experiment was in progress. Using multiple lids or a composite lid with different inlets enabled several solutions to be pumped independently in a single device. The second type of pumping lid, which relied on vapor-liquid equilibrium to generate pressure, was designed, modeled, and experimentally characterized. The pumping lid method was validated by controlling flow in different types of microfluidic applications, including the production of droplets, control of laminar flow profiles, and loading of SlipChip devices. We believe that applying the pumping lid methodology to existing microfluidic devices will enhance their use as portable diagnostic tools in limited resource settings as well as accelerate adoption of microfluidics in laboratories.

Impact of process parameters in the generation of novel aspirin nanoemulsions--comparative studies between ultrasound cavitation and microfluidizer.

PubMed

Tang, Siah Ying; Shridharan, Parthasarathy; Sivakumar, Manickam

2013-01-01

In the present investigation, the operating efficiency of a bench-top air-driven microfluidizer has been compared to that of a bench-top high power ultrasound horn in the production of pharmaceutical grade nanoemulsions using aspirin as a model drug. The influence of important process variables as well as the pre-homogenization and drug loading on the resultant mean droplet diameter and size distribution of emulsion droplets was studied in an oil-in-water nanoemulsion incorporated with a model drug aspirin. Results obtained show that both the emulsification methods were capable of producing very fine nanoemulsions containing aspirin with the minimum droplet size ranging from 150 to 170 nm. In case of using the microfluidizer, it has been observed that the size of the emulsion droplets obtained was almost independent of the applied microfluidization pressure (200-600 bar) and the number of passes (up to 10 passes) while the pre-homogenization and drug loading had a marginal effect in increasing the droplet size. Whereas, in the case of ultrasound emulsification, the droplet size was generally decreased with an increase in sonication amplitude (50-70%) and period of sonication but the resultant emulsion was found to be dependent on the pre-homogenization and drug loading. The STEM microscopic observations illustrated that the optimized formulations obtained using ultrasound cavitation technique are comparable to microfluidized emulsions. These comparative results demonstrated that ultrasound cavitation is a relatively energy-efficient yet promising method of pharmaceutical nanoemulsions as compared to microfluidizer although the means used to generate the nanoemulsions are different. Copyright © 2012 Elsevier B.V. All rights reserved.

Computational toxicology using the OpenTox application programming interface and Bioclipse

PubMed Central

2011-01-01

Background Toxicity is a complex phenomenon involving the potential adverse effect on a range of biological functions. Predicting toxicity involves using a combination of experimental data (endpoints) and computational methods to generate a set of predictive models. Such models rely strongly on being able to integrate information from many sources. The required integration of biological and chemical information sources requires, however, a common language to express our knowledge ontologically, and interoperating services to build reliable predictive toxicology applications. Findings This article describes progress in extending the integrative bio- and cheminformatics platform Bioclipse to interoperate with OpenTox, a semantic web framework which supports open data exchange and toxicology model building. The Bioclipse workbench environment enables functionality from OpenTox web services and easy access to OpenTox resources for evaluating toxicity properties of query molecules. Relevant cases and interfaces based on ten neurotoxins are described to demonstrate the capabilities provided to the user. The integration takes advantage of semantic web technologies, thereby providing an open and simplifying communication standard. Additionally, the use of ontologies ensures proper interoperation and reliable integration of toxicity information from both experimental and computational sources. Conclusions A novel computational toxicity assessment platform was generated from integration of two open science platforms related to toxicology: Bioclipse, that combines a rich scriptable and graphical workbench environment for integration of diverse sets of information sources, and OpenTox, a platform for interoperable toxicology data and computational services. The combination provides improved reliability and operability for handling large data sets by the use of the Open Standards from the OpenTox Application Programming Interface. This enables simultaneous access to a variety of distributed predictive toxicology databases, and algorithm and model resources, taking advantage of the Bioclipse workbench handling the technical layers. PMID:22075173

Microfluidics as a new tool in radiation biology

PubMed Central

Lacombe, Jerome; Phillips, Shanna Leslie; Zenhausern, Frederic

2016-01-01

Ionizing radiations interact with molecules at the cellular and molecular levels leading to several biochemical modifications that may be responsible for biological effects on tissue or whole organisms. The study of these changes is difficult because of the complexity of the biological response(s) to radiations and the lack of reliable models able to mimic the whole molecular phenomenon and different communications between the various cell networks, from the cell activation to the macroscopic effect at the tissue or organismal level. Microfluidics, the science and technology of systems that can handle small amounts of fluids in confined and controlled environment, has been an emerging field for several years. Some microfluidic devices, even at early stages of development, may already help radiobiological research by proposing new approaches to study cellular, tissue and total-body behavior upon irradiation. These devices may also be used in clinical biodosimetry since microfluidic technology is frequently developed for integrating complex bioassay chemistries into automated user-friendly, reproducible and sensitive analyses. In this review, we discuss the use, numerous advantages, and possible future of microfluidic technology in the field of radiobiology. We will also examine the disadvantages and required improvements for microfluidics to be fully practical in radiation research and to become an enabling tool for radiobiologists and radiation oncologists. PMID:26704304

Microfluidics as a new tool in radiation biology.

PubMed

Lacombe, Jerome; Phillips, Shanna Leslie; Zenhausern, Frederic

2016-02-28

Ionizing radiations interact with molecules at the cellular and molecular levels leading to several biochemical modifications that may be responsible for biological effects on tissue or whole organisms. The study of these changes is difficult because of the complexity of the biological response(s) to radiations and the lack of reliable models able to mimic the whole molecular phenomenon and different communications between the various cell networks, from the cell activation to the macroscopic effect at the tissue or organismal level. Microfluidics, the science and technology of systems that can handle small amounts of fluids in confined and controlled environment, has been an emerging field for several years. Some microfluidic devices, even at early stages of development, may already help radiobiological research by proposing new approaches to study cellular, tissue and total-body behavior upon irradiation. These devices may also be used in clinical biodosimetry since microfluidic technology is frequently developed for integrating complex bioassay chemistries into automated user-friendly, reproducible and sensitive analyses. In this review, we discuss the use, numerous advantages, and possible future of microfluidic technology in the field of radiobiology. We will also examine the disadvantages and required improvements for microfluidics to be fully practical in radiation research and to become an enabling tool for radiobiologists and radiation oncologists. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Harnessing the Use of Open Learning Exchange to Support Basic Education in Science and Mathematics in the Philippines

ERIC Educational Resources Information Center

Feliciano, Josephine S.; Mandapat, Louie Carl R.; Khan, Concepcion L.

2013-01-01

This paper presents the open learning initiatives of the Science Education Institute of the Department of Science and Technology to overcome certain barriers, such as enabling access, cost of replication, timely feedback, monitoring and continuous improvement of learning modules. Using an open-education model, like MIT's (Massachusetts Institute…

Microwave frequency sensor for detection of biological cells in microfluidic channels.

PubMed

Nikolic-Jaric, M; Romanuik, S F; Ferrier, G A; Bridges, G E; Butler, M; Sunley, K; Thomson, D J; Freeman, M R

2009-08-12

We present details of an apparatus for capacitive detection of biomaterials in microfluidic channels operating at microwave frequencies where dielectric effects due to interfacial polarization are minimal. A circuit model is presented, which can be used to adapt this detection system for use in other microfluidic applications and to identify ones where it would not be suitable. The detection system is based on a microwave coupled transmission line resonator integrated into an interferometer. At 1.5 GHz the system is capable of detecting changes in capacitance of 650 zF with a 50 Hz bandwidth. This system is well suited to the detection of biomaterials in a variety of suspending fluids, including phosphate-buffered saline. Applications involving both model particles (polystyrene microspheres) and living cells-baker's yeast (Saccharomyces cerevisiae) and Chinese hamster ovary cells-are presented.

A piezo-ring-on-chip microfluidic device for simple and low-cost mass spectrometry interfacing.

PubMed

Tsao, Chia-Wen; Lei, I-Chao; Chen, Pi-Yu; Yang, Yu-Liang

2018-02-12

Mass spectrometry (MS) interfacing technology provides the means for incorporating microfluidic processing with post MS analysis. In this study, we propose a simple piezo-ring-on-chip microfluidic device for the controlled spraying of MALDI-MS targets. This device uses a low-cost, commercially-available ring-shaped piezoelectric acoustic atomizer (piezo-ring) directly integrated into a polydimethylsiloxane microfluidic device to spray the sample onto the MS target substrate. The piezo-ring-on-chip microfluidic device's design, fabrication, and actuation, and its pulsatile pumping effects were evaluated. The spraying performance was examined by depositing organic matrix samples onto the MS target substrate by using both an automatic linear motion motor, and manual deposition. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was performed to analyze the peptide samples on the MALDI target substrates. Using our technique, model peptides with 10 -6 M concentration can be successfully detected. The results also indicate that the piezo-ring-on-chip approach forms finer matrix crystals and presents better MS signal uniformity with little sample consumption compared to the conventional pipetting method.

Well-defined porous membranes for robust omniphobic surfaces via microfluidic emulsion templating

NASA Astrophysics Data System (ADS)

Zhu, Pingan; Kong, Tiantian; Tang, Xin; Wang, Liqiu

2017-06-01

Durability is a long-standing challenge in designing liquid-repellent surfaces. A high-performance omniphobic surface must robustly repel liquids, while maintaining mechanical/chemical stability. However, liquid repellency and mechanical durability are generally mutually exclusive properties for many omniphobic surfaces--improving one performance inevitably results in decreased performance in another. Here we report well-defined porous membranes for durable omniphobic surfaces inspired by the springtail cuticle. The omniphobicity is shown via an amphiphilic material micro-textured with re-entrant surface morphology; the mechanical durability arises from the interconnected microstructures. The innovative fabrication method--termed microfluidic emulsion templating--is facile, cost-effective, scalable and can precisely engineer the structural topographies. The robust omniphobic surface is expected to open up new avenues for diverse applications due to its mechanical and chemical robustness, transparency, reversible Cassie-Wenzel transition, transferability, flexibility and stretchability.

High resolution light-sheet based high-throughput imaging cytometry system enables visualization of intra-cellular organelles

NASA Astrophysics Data System (ADS)

Regmi, Raju; Mohan, Kavya; Mondal, Partha Pratim

2014-09-01

Visualization of intracellular organelles is achieved using a newly developed high throughput imaging cytometry system. This system interrogates the microfluidic channel using a sheet of light rather than the existing point-based scanning techniques. The advantages of the developed system are many, including, single-shot scanning of specimens flowing through the microfluidic channel at flow rate ranging from micro- to nano- lit./min. Moreover, this opens-up in-vivo imaging of sub-cellular structures and simultaneous cell counting in an imaging cytometry system. We recorded a maximum count of 2400 cells/min at a flow-rate of 700 nl/min, and simultaneous visualization of fluorescently-labeled mitochondrial network in HeLa cells during flow. The developed imaging cytometry system may find immediate application in biotechnology, fluorescence microscopy and nano-medicine.

Open Access Journal Policies: A Systematic Analysis of Radiology Journals.

PubMed

Narayan, Anand; Lobner, Katie; Fritz, Jan

2018-02-01

The open access movement has pushed for greater access to scientific knowledge by expanding access to scientific journal articles. There is limited information about the extent to which open access policies have been adopted by radiology journals. We performed a systematic analysis to ascertain the proportion of radiology journals with open access options. A search was performed with the assistance of a clinical informationist. Full and mixed English-language diagnostic and interventional radiology Web of Science journals (impact factors > 1.0) were included. Nuclear medicine, radiation oncology, physics, and solicitation-only journals were excluded. Primary outcome was open access option (yes or no) with additional outcomes including presence or absence of embargo, complete or partial copyright transfer, publication fees, and self-archiving policies. Secondary outcomes included journal citations, journal impact factors, immediacy, Eigenfactor, and article influence scores. Independent double readings were performed with differences resolved by consensus, supplemented by contacting editorial staff at each journal. In all, 125 journals were identified; review yielded 49 journals (39%, mean impact factor of 2.61). Thirty-six of the journals had open access options (73.4%), and four journals were exclusively open access (8.2%). Twelve-month embargoes were most commonly cited (90.6%) with 28.6% of journals stating that they did not require a complete transfer of copyright. Prices for open access options ranged from $750 to $4,000 (median $3,000). No statistically significant differences were found in journal impact measures comparing journals with open access options to journals without open access options. Diagnostic and interventional radiology journals have widely adopted open access options with a few radiology journals being exclusively open access. Copyright © 2017 American College of Radiology. Published by Elsevier Inc. All rights reserved.

Additive manufacturing of three-dimensional (3D) microfluidic-based microelectromechanical systems (MEMS) for acoustofluidic applications.

PubMed

Cesewski, Ellen; Haring, Alexander P; Tong, Yuxin; Singh, Manjot; Thakur, Rajan; Laheri, Sahil; Read, Kaitlin A; Powell, Michael D; Oestreich, Kenneth J; Johnson, Blake N

2018-06-13

Three-dimensional (3D) printing now enables the fabrication of 3D structural electronics and microfluidics. Further, conventional subtractive manufacturing processes for microelectromechanical systems (MEMS) relatively limit device structure to two dimensions and require post-processing steps for interface with microfluidics. Thus, the objective of this work is to create an additive manufacturing approach for fabrication of 3D microfluidic-based MEMS devices that enables 3D configurations of electromechanical systems and simultaneous integration of microfluidics. Here, we demonstrate the ability to fabricate microfluidic-based acoustofluidic devices that contain orthogonal out-of-plane piezoelectric sensors and actuators using additive manufacturing. The devices were fabricated using a microextrusion 3D printing system that contained integrated pick-and-place functionality. Additively assembled materials and components included 3D printed epoxy, polydimethylsiloxane (PDMS), silver nanoparticles, and eutectic gallium-indium as well as robotically embedded piezoelectric chips (lead zirconate titanate (PZT)). Electrical impedance spectroscopy and finite element modeling studies showed the embedded PZT chips exhibited multiple resonant modes of varying mode shape over the 0-20 MHz frequency range. Flow visualization studies using neutrally buoyant particles (diameter = 0.8-70 μm) confirmed the 3D printed devices generated bulk acoustic waves (BAWs) capable of size-selective manipulation, trapping, and separation of suspended particles in droplets and microchannels. Flow visualization studies in a continuous flow format showed suspended particles could be moved toward or away from the walls of microfluidic channels based on selective actuation of in-plane or out-of-plane PZT chips. This work suggests additive manufacturing potentially provides new opportunities for the design and fabrication of acoustofluidic and microfluidic devices.

Title: SCOAP3: Explanation and Current Status

NASA Astrophysics Data System (ADS)

Marsteller, Matthew

The Sponsoring Consortium for Open Access Publishing in Particle Physics (SCOAP3) is a successful global partnership of libraries, funding agencies and research centers. SCOAP3 has negotiated with journal publishers on behalf of libraries and institutions from around the world to produce open access literature in particle physics journals that were previously published in a traditional subscription-based model. This presentation will provide an overview of the process, an update of its status and some intriguing research metrics that have emerged.

Validation of an effective, low cost, Free/open access 3D-printed stethoscope

PubMed Central

Pavlosky, Alexander; Glauche, Jennifer; Chambers, Spencer; Al-Alawi, Mahmoud; Yanev, Kliment

2018-01-01

The modern acoustic stethoscope is a useful clinical tool used to detect subtle, pathological changes in cardiac, pulmonary and vascular sounds. Currently, brand-name stethoscopes are expensive despite limited innovations in design or fabrication in recent decades. Consequently, the high cost of high quality, brand name models serves as a barrier to clinicians practicing in various settings, especially in low- and middle-income countries. In this publication, we describe the design and validation of a low-cost open-access (Free/Libre) 3D-printed stethoscope which is comparable to the Littmann Cardiology III for use in low-access clinics. PMID:29538426

SWMM5 Application Programming Interface and PySWMM: A ...

EPA Pesticide Factsheets

In support of the OpenWaterAnalytics open source initiative, the PySWMM project encompasses the development of a Python interfacing wrapper to SWMM5 with parallel ongoing development of the USEPA Stormwater Management Model (SWMM5) application programming interface (API). ... The purpose of this work is to increase the utility of the SWMM dll by creating a Toolkit API for accessing its functionality. The utility of the Toolkit is further enhanced with a wrapper to allow access from the Python scripting language. This work is being prosecuted as part of an Open Source development strategy and is being performed by volunteer software developers.

The surge of predatory open-access in neurosciences and neurology.

PubMed

Manca, Andrea; Martinez, Gianluca; Cugusi, Lucia; Dragone, Daniele; Dvir, Zeevi; Deriu, Franca

2017-06-14

Predatory open access is a controversial publishing business model that exploits the open-access system by charging publication fees in the absence of transparent editorial services. The credibility of academic publishing is now seriously threatened by predatory journals, whose articles are accorded real citations and thus contaminate the genuine scientific records of legitimate journals. This is of particular concern for public health since clinical practice relies on the findings generated by scholarly articles. Aim of this study was to compile a list of predatory journals targeting the neurosciences and neurology disciplines and to analyze the magnitude and geographical distribution of the phenomenon in these fields. Eighty-seven predatory journals operate in neurosciences and 101 in neurology, for a total of 2404 and 3134 articles issued, respectively. Publication fees range 521-637 USD, much less than those charged by genuine open-access journals. The country of origin of 26.0-37.0% of the publishers was impossible to determine due to poor websites or provision of vague or non-credible locations. Of the rest 35.3-42.0% reported their headquarters in the USA, 19.0-39.2% in India, 3.0-9.8% in other countries. Although calling themselves "open-access", none of the journals retrieved was listed in the Directory of Open Access Journals. However, 14.9-24.7% of them were found to be indexed in PubMed and PubMed Central, which raises concerns on the criteria for inclusion of journals and publishers imposed by these popular databases. Scholars in the neurosciences are advised to use all the available tools to recognize predatory practices and avoid the downsides of predatory journals. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Experimentally validated quantitative linear model for the device physics of elastomeric microfluidic valves

NASA Astrophysics Data System (ADS)

Kartalov, Emil P.; Scherer, Axel; Quake, Stephen R.; Taylor, Clive R.; Anderson, W. French

2007-03-01

A systematic experimental study and theoretical modeling of the device physics of polydimethylsiloxane "pushdown" microfluidic valves are presented. The phase space is charted by 1587 dimension combinations and encompasses 45-295μm lateral dimensions, 16-39μm membrane thickness, and 1-28psi closing pressure. Three linear models are developed and tested against the empirical data, and then combined into a fourth-power-polynomial superposition. The experimentally validated final model offers a useful quantitative prediction for a valve's properties as a function of its dimensions. Typical valves (80-150μm width) are shown to behave like thin springs.

Emerging Technologies for Cancer Research: towards Personalized Medicine with Microfluidic Platforms and 3D Tumor Models.

PubMed

Turetta, Matteo; Ben, Fabio Del; Brisotto, Giulia; Biscontin, Eva; Bulfoni, Michela; Cesselli, Daniela; Colombatti, Alfonso; Scoles, Giacinto; Gigli, Giuseppe; Del Mercato, Loretta L

2018-06-05

In the present review, we describe three hot topics in cancer research such as circulating tumor cells, exosomes, and 3D environment models. The first section is dedicated to microfluidic platforms for detecting circulating tumor cells, including both affinity-based methods that take advantage of antibodies and aptamers, and "label-free" approaches, exploiting cancer cells physical features and, more recently, abnormal cancer metabolism. In the second section, we briefly describe biology of exosomes and their role in cancer, as well as conventional techniques for their isolation and innovative microfluidic platforms. In the third section, the importance of tumor microenvironment is highlighted, along with techniques for modeling it in vitro. Finally, we discuss limitations of two-dimensional monolayer methods and describe advantages and disadvantages of different three-dimensional tumor systems for cell-cell interaction analysis and their potential applications in cancer management. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

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.

Simulation analysis of rectifying microfluidic mixing with field-effect-tunable electrothermal induced flow.

PubMed

Liu, Weiyu; Ren, Yukun; Tao, Ye; Yao, Bobin; Li, You

2018-03-01

We report herein field-effect control on in-phase electrothermal streaming from a theoretical point of view, a phenomenon termed "alternating-current electrothermal-flow field effect transistor" (ACET-FFET), in the context of a new technology for handing analytes in microfluidics. Field-effect control through a gate terminal endows ACET-FFET the ability to generate arbitrary symmetry breaking in the transverse vortex flow pattern, which makes it attractive for mixing microfluidic samples. A computational model is developed to study the feasibility of this new microfluidic device design for micromixing. The influence of various parameters on developing an efficient mixer is investigated, and an integrated layout of discrete electrode array is suggested for achieving high-throughput mixing. Our physical demonstration with field-effect electrothermal flow control using a simple electrode structure proves invaluable for designing active micromixers for modern micro total analytical system. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sample flow switching techniques on microfluidic chips.

PubMed

Pan, Yu-Jen; Lin, Jin-Jie; Luo, Win-Jet; Yang, Ruey-Jen

2006-02-15

This paper presents an experimental investigation into electrokinetically focused flow injection for bio-analytical applications. A novel microfluidic device for microfluidic sample handling is presented. The microfluidic chip is fabricated on glass substrates using conventional photolithographic and chemical etching processes and is bonded using a high-temperature fusion method. The proposed valve-less device is capable not only of directing a single sample flow to a specified output port, but also of driving multiple samples to separate outlet channels or even to a single outlet to facilitate sample mixing. The experimental results confirm that the sample flow can be electrokinetically pre-focused into a narrow stream and guided to the desired outlet port by means of a simple control voltage model. The microchip presented within this paper has considerable potential for use in a variety of applications, including high-throughput chemical analysis, cell fusion, fraction collection, sample mixing, and many other applications within the micro-total-analysis systems field.

PVDF Sensor Stimulated by Infrared Radiation for Temperature Monitoring in Microfluidic Devices.

PubMed

Pullano, Salvatore A; Mahbub, Ifana; Islam, Syed K; Fiorillo, Antonino S

2017-04-13

This paper presents a ferroelectric polymer-based temperature sensor designed for microfluidic devices. The integration of the sensor into a system-on-a-chip platform facilitates quick monitoring of localized temperature of a biological fluid, avoiding errors in the evaluation of thermal evolution of the fluid during analysis. The contact temperature sensor is fabricated by combining a thin pyroelectric film together with an infrared source, which stimulates the active element located on the top of the microfluidic channel. An experimental setup was assembled to validate the analytical model and to characterize the response rate of the device. The evaluation procedure and the operating range of the temperature also make this device suitable for applications where the localized temperature monitoring of biological samples is necessary. Additionally, ease of integration with standard microfluidic devices makes the proposed sensor an attractive option for in situ analysis of biological fluids.

Build your own soil: exploring microfluidics to create microbial habitat structures

PubMed Central

Aleklett, Kristin; Kiers, E Toby; Ohlsson, Pelle; Shimizu, Thomas S; Caldas, Victor EA; Hammer, Edith C

2018-01-01

Soil is likely the most complex ecosystem on earth. Despite the global importance and extraordinary diversity of soils, they have been notoriously challenging to study. We show how pioneering microfluidic techniques provide new ways of studying soil microbial ecology by allowing simulation and manipulation of chemical conditions and physical structures at the microscale in soil model habitats. PMID:29135971

30 CFR 291.113 - What actions may MMS take to remedy denial of open and nondiscriminatory access?

Code of Federal Regulations, 2010 CFR

2010-07-01

... open and nondiscriminatory access? 291.113 Section 291.113 Mineral Resources MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE INTERIOR APPEALS OPEN AND NONDISCRIMINATORY ACCESS TO OIL AND GAS PIPELINES... grantee or transporter has not provided open access or nondiscriminatory access, then the decision will...

Direct 3D-printing of cell-laden constructs in microfluidic architectures.

PubMed

Liu, Justin; Hwang, Henry H; Wang, Pengrui; Whang, Grace; Chen, Shaochen

2016-04-21

Microfluidic platforms have greatly benefited the biological and medical fields, however standard practices require a high cost of entry in terms of time and energy. The utilization of three-dimensional (3D) printing technologies has greatly enhanced the ability to iterate and build functional devices with unique functions. However, their inability to fabricate within microfluidic devices greatly increases the cost of producing several different devices to examine different scientific questions. In this work, a variable height micromixer (VHM) is fabricated using projection 3D-printing combined with soft lithography. Theoretical and flow experiments demonstrate that altering the local z-heights of VHM improved mixing at lower flow rates than simple geometries. Mixing of two fluids occurs as low as 320 μL min(-1) in VHM whereas the planar zigzag region requires a flow rate of 2.4 mL min(-1) before full mixing occurred. Following device printing, to further demonstrate the ability of this projection-based method, complex, user-defined cell-laden scaffolds are directly printed inside the VHM. The utilization of this unique ability to produce 3D tissue models within a microfluidic system could offer a unique platform for medical diagnostics and disease modeling.

Optical measurement of transverse molecular diffusion in a microchannel.

PubMed Central

Kamholz, A E; Schilling, E A; Yager, P

2001-01-01

Quantitative analysis of molecular diffusion is a necessity for the efficient design of most microfluidic devices as well as an important biophysical method in its own right. This study demonstrates the rapid measurement of diffusion coefficients of large and small molecules in a microfluidic device, the T-sensor, by means of conventional epifluorescence microscopy. Data were collected by monitoring the transverse flux of analyte from a sample stream into a second stream flowing alongside it. As indicated by the low Reynolds numbers of the system (< 1), flow is laminar, and molecular transport between streams occurs only by diffusion. Quantitative determinations were made by fitting data with predictions of a one-dimensional model. Analysis was made of the flow development and its effect on the distribution of diffusing analyte using a three-dimensional modeling software package. Diffusion coefficients were measured for four fluorescently labeled molecules: fluorescein-biotin, insulin, ovalbumin, and streptavidin. The resulting values differed from accepted results by an average of 2.4%. Microfluidic system parameters can be selected to achieve accurate diffusion coefficient measurements and to optimize other microfluidic devices that rely on precise transverse transport of molecules. PMID:11259309

Blood-plasma separation in Y-shaped bifurcating microfluidic channels: A dissipative particle dynamics simulation study

PubMed Central

Li, Xuejin; Popel, Aleksander S.; Karniadakis, George Em

2012-01-01

The motion of a suspension of red blood cells (RBCs) flowing in a Y-shaped bifurcating microfluidic channel is investigated using a validated low-dimensional RBC (LD-RBC) model based on dissipative particle dynamics (DPD). Specifically, the RBC is represented as a closed torus-like ring of ten colloidal particles, which leads to efficient simulations of blood flow in microcirculation over a wide range of hematocrits. Adaptive no-slip wall boundary conditions were implemented to model hydrodynamic flow within a specific wall structure of diverging 3D microfluidic channels, paying attention to controlling density fluctuations. Plasma skimming and the all-or-nothing phenomenon of RBCs in a bifurcating microfluidic channel have been investigated in our simulations for healthy and diseased blood, including the size of cell-free layer on the daughter branches. The feed hematocrit level in the parent channel has considerable influence on blood-plasma separation. Compared to the blood-plasma separation efficiencies of healthy RBCs, malaria-infected stiff RBCs (iRBCs) have a tendency to travel into the low flowrate daughter branch because of their different initial distribution in the parent channel. Our simulation results are consistent with previously published experimental results and theoretical predictions. PMID:22476709

Open access to scientific research: where are we and where are we going? Facts and figures on the occasion of the 2010 Open Access Week (October 18-24).

PubMed

Giglia, E

2010-09-01

This contribution is aimed at presenting a sort of "state of the art" of Open Access on the occasion of the 2010 international Open Access Week, to be held from October 18 to October 24. We shall see facts and figures about open archives and the mandates to deposit; about Open Access journals; about impact and citation advantages for the researchers, and about economic sustainability.

Open access, library and publisher competition, and the evolution of general commerce.

PubMed

Odlyzko, Andrew M

2015-02-01

Discussions of the economics of scholarly communication are usually devoted to Open Access, rising journal prices, publisher profits, and boycotts. That ignores what seems a much more important development in this market. Publishers, through the oft-reviled Big Deal packages, are providing much greater and more egalitarian access to the journal literature, an approximation to true Open Access. In the process, they are also marginalizing libraries and obtaining a greater share of the resources going into scholarly communication. This is enabling a continuation of publisher profits as well as of what for decades has been called "unsustainable journal price escalation." It is also inhibiting the spread of Open Access and potentially leading to an oligopoly of publishers controlling distribution through large-scale licensing. The Big Deal practices are worth studying for several general reasons. The degree to which publishers succeed in diminishing the role of libraries may be an indicator of the degree and speed at which universities transform themselves. More importantly, these Big Deals appear to point the way to the future of the whole economy, where progress is characterized by declining privacy, increasing price discrimination, increasing opaqueness in pricing, increasing reliance on low-paid or unpaid work of others for profits, and business models that depend on customer inertia. © The Author(s) 2014.

Optical diagnostics of osteoblast cells and osteogenic drug screening

NASA Astrophysics Data System (ADS)

Kolanti, Elayaraja; Veerla, Sarath C.; Khajuria, Deepak K.; Roy Mahapatra, D.

2016-02-01

Microfluidic device based diagnostics involving optical fibre path, in situ imaging and spectroscopy are gaining importance due to recent advances in diagnostics instrumentation and methods, besides other factors such as low amount of reagent required for analysis, short investigation times, and potential possibilities to replace animal model based study in near future. It is possible to grow and monitor tissues in vitro in microfluidic lab-on-chip. It may become a transformative way of studying how cells interact with drugs, pathogens and biomaterials in physiologically relevant microenvironments. To a large extent, progress in developing clinically viable solutions has been constrained because of (i) contradiction between in vitro and in vivo results and (ii) animal model based and clinical studies which is very expensive. Our study here aims to evaluate the usefulness of microfluidic device based 3D tissue growth and monitoring approach to better emulate physiologically and clinically relevant microenvironments in comparison to conventional in vitro 2D culture. Moreover, the microfluidic methodology permits precise high-throughput investigations through real-time imaging while using very small amounts of reagents and cells. In the present study, we report on the details of an osteoblast cell based 3D microfluidic platform which we employ for osteogenic drug screening. The drug formulation is functionalized with fluorescence and other biomarkers for imaging and spectroscopy, respectively. Optical fibre coupled paths are used to obtain insight regarding the role of stress/flow pressure fluctuation and nanoparticle-drug concentration on the osteoblast growth and osteogenic properties of bone.

Organ/body-on-a-chip based on microfluidic technology for drug discovery.

PubMed

Kimura, Hiroshi; Sakai, Yasuyuki; Fujii, Teruo

2018-02-01

Although animal experiments are indispensable for preclinical screening in the drug discovery process, various issues such as ethical considerations and species differences remain. To solve these issues, cell-based assays using human-derived cells have been actively pursued. However, it remains difficult to accurately predict drug efficacy, toxicity, and organs interactions, because cultivated cells often do not retain their original organ functions and morphologies in conventional in vitro cell culture systems. In the μTAS research field, which is a part of biochemical engineering, the technologies of organ-on-a-chip, based on microfluidic devices built using microfabrication, have been widely studied recently as a novel in vitro organ model. Since it is possible to physically and chemically mimic the in vitro environment by using microfluidic device technology, maintenance of cellular function and morphology, and replication of organ interactions can be realized using organ-on-a-chip devices. So far, functions of various organs and tissues, such as the lung, liver, kidney, and gut have been reproduced as in vitro models. Furthermore, a body-on-a-chip, integrating multi organ functions on a microfluidic device, has also been proposed for prediction of organ interactions. We herein provide a background of microfluidic systems, organ-on-a-chip, Body-on-a-chip technologies, and their challenges in the future. Copyright © 2017 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

Rapid and inexpensive fabrication of polymeric microfluidic devices via toner transfer masking

PubMed Central

Easley, Christopher J.; Benninger, Richard K. P.; Shaver, Jesse H.; Head, W. Steven; Piston, David W.

2009-01-01

Summary An alternative fabrication method is presented for production of masters for single- or multilayer polymeric microfluidic devices in a standard laboratory environment, precluding the need for a cleanroom. This toner transfer masking (TTM) method utilizes an office laser printer to generate a toner pattern which is thermally transferred to a metal master to serve as a mask for etching. With master fabrication times as little as one hour (depending on channel depth) using commercially-available equipment and supplies, this approach should make microfluidic technology more widely accessible to the non-expert—even the non-scientist. The cost of fabrication consumables was estimated to be < $1 per master, over an order of magnitude decrease in consumable costs compared to standard photolithography. In addition, the use of chemical etching allows accurate control over the height of raised features (i.e., channel depths), allowing the flexibility to fabricate multiple depths on a single master with little added time. Resultant devices are shown capable of pneumatic valving, three-dimensional channel formation (using layer-connecting vias), droplet fluidics, and cell imaging and staining. The multiple-depth capabilities of the method are proven useful for cellular analysis by fabrication of handheld, disposable devices used for trapping and imaging of live murine pancreatic islets. The precise fluidic control provided by the microfluidic platform allows subsequent fixing and staining of these cells without significant movement, thus spatial correlation of imaging and staining is attainable—even with rare alpha cells that constitute only ∼10% of the islet cells. PMID:19350094

Sample to answer visualization pipeline for low-cost point-of-care blood cell counting

NASA Astrophysics Data System (ADS)

Smith, Suzanne; Naidoo, Thegaran; Davies, Emlyn; Fourie, Louis; Nxumalo, Zandile; Swart, Hein; Marais, Philip; Land, Kevin; Roux, Pieter

2015-03-01

We present a visualization pipeline from sample to answer for point-of-care blood cell counting applications. Effective and low-cost point-of-care medical diagnostic tests provide developing countries and rural communities with accessible healthcare solutions [1], and can be particularly beneficial for blood cell count tests, which are often the starting point in the process of diagnosing a patient [2]. The initial focus of this work is on total white and red blood cell counts, using a microfluidic cartridge [3] for sample processing. Analysis of the processed samples has been implemented by means of two main optical visualization systems developed in-house: 1) a fluidic operation analysis system using high speed video data to determine volumes, mixing efficiency and flow rates, and 2) a microscopy analysis system to investigate homogeneity and concentration of blood cells. Fluidic parameters were derived from the optical flow [4] as well as color-based segmentation of the different fluids using a hue-saturation-value (HSV) color space. Cell count estimates were obtained using automated microscopy analysis and were compared to a widely accepted manual method for cell counting using a hemocytometer [5]. The results using the first iteration microfluidic device [3] showed that the most simple - and thus low-cost - approach for microfluidic component implementation was not adequate as compared to techniques based on manual cell counting principles. An improved microfluidic design has been developed to incorporate enhanced mixing and metering components, which together with this work provides the foundation on which to successfully implement automated, rapid and low-cost blood cell counting tests.

Chemotaxis and auto-chemotaxis of self-propelling artificial droplet swimmers

NASA Astrophysics Data System (ADS)

Jin, Chenyu; Krueger, Carsten; Maass, Corinna

Chemotaxis and auto-chemotaxis are key mechanisms in the dynamics of micro-organisms, e.g. in the acquisition of nutrients and in the communication between individuals, influencing the collective behavior. However, chemical signalling and the natural environment of biological swimmers are generally complex, making them hard to access analytically. Simple experimental systems showing similar features could provide vital insights. We present such a swimmer system, as well as controlled assays to study chemotactic effects quantitatively and reproducibly. In our experiments, we let auto-chemotactic droplet swimmers pass through bifurcating microfluidic channels and record anticorrelations between the branch choices of consecutive droplets. We present an analytical model based on balancing stochastic forces versus a diffusing chemical gradient matching the experimental data. supported by the DFG SPP 1726 ''Microswimmers'' and the MaxSynBio network.

Microbiome-on-a-Chip: New Frontiers in Plant-Microbiota Research.

PubMed

Stanley, Claire E; van der Heijden, Marcel G A

2017-08-01

An enigmatic concoction of interactions between microbes and hosts takes place below ground, yet the function(s) of the individual components in this complex playground are far from understood. This Forum article highlights how microfluidic - or 'Microbiome-on-a-Chip' - technology could help to shed light on such relationships, opening new frontiers in plant-microbiota research. Copyright © 2017 Elsevier Ltd. All rights reserved.

Open-Access Textbooks and Financial Sustainability: A Case Study on Flat World Knowledge

ERIC Educational Resources Information Center

Hilton, John, III; Wiley, David

2011-01-01

Many college students and their families are concerned about the high costs of textbooks. A company called Flat World Knowledge both gives away and sells open-source textbooks in a way it believes to be financially sustainable. This article reports on the financial sustainability of the Flat World Knowledge open-source textbook model after one…

The Open Access Model of Meteorologische Zeitschrift and other meteorological journals

NASA Astrophysics Data System (ADS)

Emeis, S.

2009-09-01

Today's availability and possibilities of the internet have already brought significant changes to the means of scientific communication. This also affects the publication and reception of peer-reviewed papers in scientific journals. In pre-internet times, the publication of scientific journals was mainly financed through subscription fees paid by libraries and other subscribers. The readers went to the libraries of their institution to search, read, and photocopy these papers. Today, everybody expects to have scientific papers more or less freely available on their desktop computers and from their printers. This has forced the publishers to change the financial model for the publication of scientific papers. An increasing number of journals now publish papers whose production costs have to be paid before the publication by the author or its institution. Those "pre-paid” papers are then freely available from the internet. This publication model has become known as "Open Access (OA)” model. Also the 126-year old Meteorologische Zeitschrift has changed its publication model to an Optional Open Access model. The features of this model will be presented and compared to other OA models with meteorological journals. This change in the publication models with a shift of its payment from the end (libraries and subscribers) to the beginning of the publication process (authors) has also confronted the scientific research and funding institutions with some problems. They must now also change their structures in financing one of their major outputs, the publications of their researchers. A few aspects of the present state of this shift will be addressed.

OpenTox predictive toxicology framework: toxicological ontology and semantic media wiki-based OpenToxipedia

PubMed Central

2012-01-01

Background The OpenTox Framework, developed by the partners in the OpenTox project (http://www.opentox.org), aims at providing a unified access to toxicity data, predictive models and validation procedures. Interoperability of resources is achieved using a common information model, based on the OpenTox ontologies, describing predictive algorithms, models and toxicity data. As toxicological data may come from different, heterogeneous sources, a deployed ontology, unifying the terminology and the resources, is critical for the rational and reliable organization of the data, and its automatic processing. Results The following related ontologies have been developed for OpenTox: a) Toxicological ontology – listing the toxicological endpoints; b) Organs system and Effects ontology – addressing organs, targets/examinations and effects observed in in vivo studies; c) ToxML ontology – representing semi-automatic conversion of the ToxML schema; d) OpenTox ontology– representation of OpenTox framework components: chemical compounds, datasets, types of algorithms, models and validation web services; e) ToxLink–ToxCast assays ontology and f) OpenToxipedia community knowledge resource on toxicology terminology. OpenTox components are made available through standardized REST web services, where every compound, data set, and predictive method has a unique resolvable address (URI), used to retrieve its Resource Description Framework (RDF) representation, or to initiate the associated calculations and generate new RDF-based resources. The services support the integration of toxicity and chemical data from various sources, the generation and validation of computer models for toxic effects, seamless integration of new algorithms and scientifically sound validation routines and provide a flexible framework, which allows building arbitrary number of applications, tailored to solving different problems by end users (e.g. toxicologists). Availability The OpenTox toxicological ontology projects may be accessed via the OpenTox ontology development page http://www.opentox.org/dev/ontology; the OpenTox ontology is available as OWL at http://opentox.org/api/1 1/opentox.owl, the ToxML - OWL conversion utility is an open source resource available at http://ambit.svn.sourceforge.net/viewvc/ambit/branches/toxml-utils/ PMID:22541598

OpenTox predictive toxicology framework: toxicological ontology and semantic media wiki-based OpenToxipedia.

PubMed

Tcheremenskaia, Olga; Benigni, Romualdo; Nikolova, Ivelina; Jeliazkova, Nina; Escher, Sylvia E; Batke, Monika; Baier, Thomas; Poroikov, Vladimir; Lagunin, Alexey; Rautenberg, Micha; Hardy, Barry

2012-04-24

The OpenTox Framework, developed by the partners in the OpenTox project (http://www.opentox.org), aims at providing a unified access to toxicity data, predictive models and validation procedures. Interoperability of resources is achieved using a common information model, based on the OpenTox ontologies, describing predictive algorithms, models and toxicity data. As toxicological data may come from different, heterogeneous sources, a deployed ontology, unifying the terminology and the resources, is critical for the rational and reliable organization of the data, and its automatic processing. The following related ontologies have been developed for OpenTox: a) Toxicological ontology - listing the toxicological endpoints; b) Organs system and Effects ontology - addressing organs, targets/examinations and effects observed in in vivo studies; c) ToxML ontology - representing semi-automatic conversion of the ToxML schema; d) OpenTox ontology- representation of OpenTox framework components: chemical compounds, datasets, types of algorithms, models and validation web services; e) ToxLink-ToxCast assays ontology and f) OpenToxipedia community knowledge resource on toxicology terminology.OpenTox components are made available through standardized REST web services, where every compound, data set, and predictive method has a unique resolvable address (URI), used to retrieve its Resource Description Framework (RDF) representation, or to initiate the associated calculations and generate new RDF-based resources.The services support the integration of toxicity and chemical data from various sources, the generation and validation of computer models for toxic effects, seamless integration of new algorithms and scientifically sound validation routines and provide a flexible framework, which allows building arbitrary number of applications, tailored to solving different problems by end users (e.g. toxicologists). The OpenTox toxicological ontology projects may be accessed via the OpenTox ontology development page http://www.opentox.org/dev/ontology; the OpenTox ontology is available as OWL at http://opentox.org/api/1 1/opentox.owl, the ToxML - OWL conversion utility is an open source resource available at http://ambit.svn.sourceforge.net/viewvc/ambit/branches/toxml-utils/

Use of Open Standards and Technologies at the Lunar Mapping and Modeling Project

NASA Astrophysics Data System (ADS)

Law, E.; Malhotra, S.; Bui, B.; Chang, G.; Goodale, C. E.; Ramirez, P.; Kim, R. M.; Sadaqathulla, S.; Rodriguez, L.

2011-12-01

The Lunar Mapping and Modeling Project (LMMP), led by the Marshall Space Flight center (MSFC), is tasked by NASA. The project is responsible for the development of an information system to support lunar exploration activities. It provides lunar explorers a set of tools and lunar map and model products that are predominantly derived from present lunar missions (e.g., the Lunar Reconnaissance Orbiter (LRO)) and from historical missions (e.g., Apollo). At Jet Propulsion Laboratory (JPL), we have built the LMMP interoperable geospatial information system's underlying infrastructure and a single point of entry - the LMMP Portal by employing a number of open standards and technologies. The Portal exposes a set of services to users to allow search, visualization, subset, and download of lunar data managed by the system. Users also have access to a set of tools that visualize, analyze and annotate the data. The infrastructure and Portal are based on web service oriented architecture. We designed the system to support solar system bodies in general including asteroids, earth and planets. We employed a combination of custom software, commercial and open-source components, off-the-shelf hardware and pay-by-use cloud computing services. The use of open standards and web service interfaces facilitate platform and application independent access to the services and data, offering for instances, iPad and Android mobile applications and large screen multi-touch with 3-D terrain viewing functions, for a rich browsing and analysis experience from a variety of platforms. The web services made use of open standards including: Representational State Transfer (REST); and Open Geospatial Consortium (OGC)'s Web Map Service (WMS), Web Coverage Service (WCS), Web Feature Service (WFS). Its data management services have been built on top of a set of open technologies including: Object Oriented Data Technology (OODT) - open source data catalog, archive, file management, data grid framework; openSSO - open source access management and federation platform; solr - open source enterprise search platform; redmine - open source project collaboration and management framework; GDAL - open source geospatial data abstraction library; and others. Its data products are compliant with Federal Geographic Data Committee (FGDC) metadata standard. This standardization allows users to access the data products via custom written applications or off-the-shelf applications such as GoogleEarth. We will demonstrate this ready-to-use system for data discovery and visualization by walking through the data services provided through the portal such as browse, search, and other tools. We will further demonstrate image viewing and layering of lunar map images from the Internet, via mobile devices such as Apple's iPad.

A high-performance polydimethylsiloxane electrospun membrane for cell culture in lab-on-a-chip.

PubMed

Moghadas, Hajar; Saidi, Mohammad Said; Kashaninejad, Navid; Nguyen, Nam-Trung

2018-03-01

Thin porous membranes are important components in a microfluidic device, serving as separators, filters, and scaffolds for cell culture. However, the fabrication and the integration of these membranes possess many challenges, which restrict their widespread applications. This paper reports a facile technique to fabricate robust membrane-embedded microfluidic devices. We integrated an electrospun membrane into a polydimethylsiloxane (PDMS) device using the simple plasma-activated bonding technique. To increase the flexibility of the membrane and to address the leakage problem, the electrospun membrane was fabricated with the highest weight ratio of PDMS to polymethylmethacrylate (i.e., 6:1 w/w). The membrane-integrated microfluidic device could withstand a flow rate of up to 50  μ l/min. As a proof of concept, we demonstrated that such a compartmentalized microfluidic platform could be successfully used for cell culture with the capability of providing a more realistic in vivo -like condition. Human lung cancer epithelial cells (A549) were seeded on the membrane from the top microchannel, while the continuous flow of the culture medium through the bottom microchannel provided a shear-free cell culture condition. The tortuous micro-/nanofibers of the membrane immobilized the cells within the hydrophobic micropores and with no need of extracellular matrix for cell adhesion and cell growth. The hydrophobic surface conditions of the membrane were suitable for anchorage-independent cell types. To further extend the application of the device, we qualitatively showed that rinsing the membrane with ethanol prior to cell seeding could temporarily render the membrane hydrophilic and the platform could also be used for anchorage-dependent cells. Due to the three-dimensional (3D) topography of the membranes, three different configurations were observed, including individual single cells, monolayer cells, and 3D cell clusters. This cost-effective and robust compartmentalized microfluidic device may open up new avenues in translational medicine and pharmacodynamics research.

Open access publishing, article downloads, and citations: randomised controlled trial

PubMed Central

Lewenstein, Bruce V; Simon, Daniel H; Booth, James G; Connolly, Mathew J L

2008-01-01

Objective To measure the effect of free access to the scientific literature on article downloads and citations. Design Randomised controlled trial. Setting 11 journals published by the American Physiological Society. Participants 1619 research articles and reviews. Main outcome measures Article readership (measured as downloads of full text, PDFs, and abstracts) and number of unique visitors (internet protocol addresses). Citations to articles were gathered from the Institute for Scientific Information after one year. Interventions Random assignment on online publication of articles published in 11 scientific journals to open access (treatment) or subscription access (control). Results Articles assigned to open access were associated with 89% more full text downloads (95% confidence interval 76% to 103%), 42% more PDF downloads (32% to 52%), and 23% more unique visitors (16% to 30%), but 24% fewer abstract downloads (−29% to −19%) than subscription access articles in the first six months after publication. Open access articles were no more likely to be cited than subscription access articles in the first year after publication. Fifty nine per cent of open access articles (146 of 247) were cited nine to 12 months after publication compared with 63% (859 of 1372) of subscription access articles. Logistic and negative binomial regression analysis of article citation counts confirmed no citation advantage for open access articles. Conclusions Open access publishing may reach more readers than subscription access publishing. No evidence was found of a citation advantage for open access articles in the first year after publication. The citation advantage from open access reported widely in the literature may be an artefact of other causes. PMID:18669565

Topographic mapping data semantics through data conversion and enhancement: Chapter 7

USGS Publications Warehouse

Varanka, Dalia; Carter, Jonathan; Usery, E. Lynn; Shoberg, Thomas; Edited by Ashish, Naveen; Sheth, Amit P.

2011-01-01

This paper presents research on the semantics of topographic data for triples and ontologies to blend the capabilities of the Semantic Web and The National Map of the U.S. Geological Survey. Automated conversion of relational topographic data of several geographic sample areas to the triple data model standard resulted in relatively poor semantic associations. Further research employed vocabularies of feature type and spatial relation terms. A user interface was designed to model the capture of non-standard terms relevant to public users and to map those terms to existing data models of The National Map through the use of ontology. Server access for the study area triple stores was made publicly available, illustrating how the development of linked data may transform institutional policies to open government data resources to the public. This paper presents these data conversion and research techniques that were tested as open linked data concepts leveraged through a user-centered interface and open USGS server access to the public.

Aptamer-based microfluidic beads array sensor for simultaneous detection of multiple analytes employing multienzyme-linked nanoparticle amplification and quantum dots labels.

PubMed

Zhang, He; Hu, Xinjiang; Fu, Xin

2014-07-15

This study reports the development of an aptamer-mediated microfluidic beads-based sensor for multiple analytes detection and quantification using multienzyme-linked nanoparticle amplification and quantum dots labels. Adenosine and cocaine were selected as the model analytes to validate the assay design based on strand displacement induced by target-aptamer complex. Microbeads functionalized with the aptamers and modified electron rich proteins were arrayed within a microfluidic channel and were connected with the horseradish peroxidases (HRP) and capture DNA probe derivative gold nanoparticles (AuNPs) via hybridization. The conformational transition of aptamer induced by target-aptamer complex contributes to the displacement of functionalized AuNPs and decreases the fluorescence signal of microbeads. In this approach, increased binding events of HRP on each nanosphere and enhanced mass transport capability inherent from microfluidics are integrated for enhancing the detection sensitivity of analytes. Based on the dual signal amplification strategy, the developed aptamer-based microfluidic bead array sensor could discriminate as low as 0.1 pM of adenosine and 0.5 pM cocaine, and showed a 500-fold increase in detection limit of adenosine compared to the off-chip test. The results proved the microfluidic-based method was a rapid and efficient system for aptamer-based targets assays (adenosine (0.1 pM) and cocaine (0.5 pM)), requiring only minimal (microliter) reagent use. This work demonstrated the successful application of aptamer-based microfluidic beads array sensor for detection of important molecules in biomedical fields. Copyright © 2014 Elsevier B.V. All rights reserved.

Microfluidic Droplet-Facilitated Hierarchical Assembly for Dual Cargo Loading and Synergistic Delivery.

PubMed

Yu, Ziyi; Zheng, Yu; Parker, Richard M; Lan, Yang; Wu, Yuchao; Coulston, Roger J; Zhang, Jing; Scherman, Oren A; Abell, Chris

2016-04-06

Bottom-up hierarchical assembly has emerged as an elaborate and energy-efficient strategy for the fabrication of smart materials. Herein, we present a hierarchical assembly process, whereby linear amphiphilic block copolymers are self-assembled into micelles, which in turn are accommodated at the interface of microfluidic droplets via cucurbit[8]uril-mediated host-guest chemistry to form supramolecular microcapsules. The monodisperse microcapsules can be used for simultaneous carriage of both organic (Nile Red) and aqueous-soluble (fluorescein isothiocyanate-dextran) cargo. Furthermore, the well-defined compartmentalized structure benefits from the dynamic nature of the supramolecular interaction and offers synergistic delivery of cargos with triggered release or through photocontrolled porosity. This demonstration of premeditated hierarchical assembly, where interactions from the molecular to microscale are designed, illustrates the power of this route toward accessing the next generation of functional materials and encapsulation strategies.

Novel droplet platforms for the detection of disease biomarkers.

PubMed

Zec, Helena; Shin, Dong Jin; Wang, Tza-Huei

2014-09-01

Personalized medicine - healthcare based on individual genetic variation - has the potential to transform the way healthcare is delivered to patients. The promise of personalized medicine has been predicated on the predictive and diagnostic power of genomic and proteomic biomarkers. Biomarker screening may help improve health outcomes, for example, by identifying individuals' susceptibility to diseases and predicting how patients will respond to drugs. Microfluidic droplet technology offers an exciting opportunity to revolutionize the accessibility of personalized medicine. A framework for the role of droplet microfluidics in biomarker detection can be based on two main themes. Emulsion-based microdroplet platforms can provide new ways to measure and detect biomolecules. In addition, microdroplet platforms facilitate high-throughput screening of biomarkers. Meanwhile, surface-based droplet platforms provide an opportunity to develop miniaturized diagnostic systems. These platforms may function as portable benchtop environments that dramatically shorten the transition of a benchtop assay into a point-of-care format.

Nanoparticle functionalised small-core suspended-core fibre - a novel platform for efficient sensing.

PubMed

Doherty, Brenda; Csáki, Andrea; Thiele, Matthias; Zeisberger, Matthias; Schwuchow, Anka; Kobelke, Jens; Fritzsche, Wolfgang; Schmidt, Markus A

2017-02-01

Detecting small quantities of specific target molecules is of major importance within bioanalytics for efficient disease diagnostics. One promising sensing approach relies on combining plasmonically-active waveguides with microfluidics yielding an easy-to-use sensing platform. Here we introduce suspended-core fibres containing immobilised plasmonic nanoparticles surrounding the guiding core as a concept for an entirely integrated optofluidic platform for efficient refractive index sensing. Due to the extremely small optical core and the large adjacent microfluidic channels, over two orders of magnitude of nanoparticle coverage densities have been accessed with millimetre-long sample lengths showing refractive index sensitivities of 170 nm/RIU for aqueous analytes where the fibre interior is functionalised by gold nanospheres. Our concept represents a fully integrated optofluidic sensing system demanding small sample volumes and allowing for real-time analyte monitoring, both of which are highly relevant within invasive bioanalytics, particularly within molecular disease diagnostics and environmental science.

The academic, economic and societal impacts of Open Access: an evidence-based review.

PubMed

Tennant, Jonathan P; Waldner, François; Jacques, Damien C; Masuzzo, Paola; Collister, Lauren B; Hartgerink, Chris H J

2016-01-01

Ongoing debates surrounding Open Access to the scholarly literature are multifaceted and complicated by disparate and often polarised viewpoints from engaged stakeholders. At the current stage, Open Access has become such a global issue that it is critical for all involved in scholarly publishing, including policymakers, publishers, research funders, governments, learned societies, librarians, and academic communities, to be well-informed on the history, benefits, and pitfalls of Open Access. In spite of this, there is a general lack of consensus regarding the potential pros and cons of Open Access at multiple levels. This review aims to be a resource for current knowledge on the impacts of Open Access by synthesizing important research in three major areas: academic, economic and societal. While there is clearly much scope for additional research, several key trends are identified, including a broad citation advantage for researchers who publish openly, as well as additional benefits to the non-academic dissemination of their work. The economic impact of Open Access is less well-understood, although it is clear that access to the research literature is key for innovative enterprises, and a range of governmental and non-governmental services. Furthermore, Open Access has the potential to save both publishers and research funders considerable amounts of financial resources, and can provide some economic benefits to traditionally subscription-based journals. The societal impact of Open Access is strong, in particular for advancing citizen science initiatives, and leveling the playing field for researchers in developing countries. Open Access supersedes all potential alternative modes of access to the scholarly literature through enabling unrestricted re-use, and long-term stability independent of financial constraints of traditional publishers that impede knowledge sharing. However, Open Access has the potential to become unsustainable for research communities if high-cost options are allowed to continue to prevail in a widely unregulated scholarly publishing market. Open Access remains only one of the multiple challenges that the scholarly publishing system is currently facing. Yet, it provides one foundation for increasing engagement with researchers regarding ethical standards of publishing and the broader implications of 'Open Research'.

The academic, economic and societal impacts of Open Access: an evidence-based review

PubMed Central

Tennant, Jonathan P.; Waldner, François; Jacques, Damien C.; Masuzzo, Paola; Collister, Lauren B.; Hartgerink, Chris. H. J.

2016-01-01

Ongoing debates surrounding Open Access to the scholarly literature are multifaceted and complicated by disparate and often polarised viewpoints from engaged stakeholders. At the current stage, Open Access has become such a global issue that it is critical for all involved in scholarly publishing, including policymakers, publishers, research funders, governments, learned societies, librarians, and academic communities, to be well-informed on the history, benefits, and pitfalls of Open Access. In spite of this, there is a general lack of consensus regarding the potential pros and cons of Open Access at multiple levels. This review aims to be a resource for current knowledge on the impacts of Open Access by synthesizing important research in three major areas: academic, economic and societal. While there is clearly much scope for additional research, several key trends are identified, including a broad citation advantage for researchers who publish openly, as well as additional benefits to the non-academic dissemination of their work. The economic impact of Open Access is less well-understood, although it is clear that access to the research literature is key for innovative enterprises, and a range of governmental and non-governmental services. Furthermore, Open Access has the potential to save both publishers and research funders considerable amounts of financial resources, and can provide some economic benefits to traditionally subscription-based journals. The societal impact of Open Access is strong, in particular for advancing citizen science initiatives, and leveling the playing field for researchers in developing countries. Open Access supersedes all potential alternative modes of access to the scholarly literature through enabling unrestricted re-use, and long-term stability independent of financial constraints of traditional publishers that impede knowledge sharing. However, Open Access has the potential to become unsustainable for research communities if high-cost options are allowed to continue to prevail in a widely unregulated scholarly publishing market. Open Access remains only one of the multiple challenges that the scholarly publishing system is currently facing. Yet, it provides one foundation for increasing engagement with researchers regarding ethical standards of publishing and the broader implications of 'Open Research'. PMID:27158456

Predatory Publishing, Questionable Peer Review, and Fraudulent Conferences

PubMed Central

2014-01-01

Open-access is a model for publishing scholarly, peer-reviewed journals on the Internet that relies on sources of funding other than subscription fees. Some publishers and editors have exploited the author-pays model of open-access, publishing for their own profit. Submissions are encouraged through widely distributed e-mails on behalf of a growing number of journals that may accept many or all submissions and subject them to little, if any, peer review or editorial oversight. Bogus conference invitations are distributed in a similar fashion. The results of these less than ethical practices might include loss of faculty member time and money, inappropriate article inclusions in curriculum vitae, and costs to the college or funding source. PMID:25657363

A numerical study of blood flow using mixture theory

PubMed Central

Wu, Wei-Tao; Aubry, Nadine; Massoudi, Mehrdad; Kim, Jeongho; Antaki, James F.

2014-01-01

In this paper, we consider the two dimensional flow of blood in a rectangular microfluidic channel. We use Mixture Theory to treat this problem as a two-component system: One component is the red blood cells (RBCs) modeled as a generalized Reiner–Rivlin type fluid, which considers the effects of volume fraction (hematocrit) and influence of shear rate upon viscosity. The other component, plasma, is assumed to behave as a linear viscous fluid. A CFD solver based on OpenFOAM® was developed and employed to simulate a specific problem, namely blood flow in a two dimensional micro-channel, is studied. Finally to better understand this two-component flow system and the effects of the different parameters, the equations are made dimensionless and a parametric study is performed. PMID:24791016

A numerical study of blood flow using mixture theory.

PubMed

Wu, Wei-Tao; Aubry, Nadine; Massoudi, Mehrdad; Kim, Jeongho; Antaki, James F

2014-03-01

In this paper, we consider the two dimensional flow of blood in a rectangular microfluidic channel. We use Mixture Theory to treat this problem as a two-component system: One component is the red blood cells (RBCs) modeled as a generalized Reiner-Rivlin type fluid, which considers the effects of volume fraction (hematocrit) and influence of shear rate upon viscosity. The other component, plasma, is assumed to behave as a linear viscous fluid. A CFD solver based on OpenFOAM ® was developed and employed to simulate a specific problem, namely blood flow in a two dimensional micro-channel, is studied. Finally to better understand this two-component flow system and the effects of the different parameters, the equations are made dimensionless and a parametric study is performed.

Potential predatory and legitimate biomedical journals: can you tell the difference? A cross-sectional comparison.

PubMed

Shamseer, Larissa; Moher, David; Maduekwe, Onyi; Turner, Lucy; Barbour, Virginia; Burch, Rebecca; Clark, Jocalyn; Galipeau, James; Roberts, Jason; Shea, Beverley J

2017-03-16

The Internet has transformed scholarly publishing, most notably, by the introduction of open access publishing. Recently, there has been a rise of online journals characterized as 'predatory', which actively solicit manuscripts and charge publications fees without providing robust peer review and editorial services. We carried out a cross-sectional comparison of characteristics of potential predatory, legitimate open access, and legitimate subscription-based biomedical journals. On July 10, 2014, scholarly journals from each of the following groups were identified - potential predatory journals (source: Beall's List), presumed legitimate, fully open access journals (source: PubMed Central), and presumed legitimate subscription-based (including hybrid) journals (source: Abridged Index Medicus). MEDLINE journal inclusion criteria were used to screen and identify biomedical journals from within the potential predatory journals group. One hundred journals from each group were randomly selected. Journal characteristics (e.g., website integrity, look and feel, editors and staff, editorial/peer review process, instructions to authors, publication model, copyright and licensing, journal location, and contact) were collected by one assessor and verified by a second. Summary statistics were calculated. Ninety-three predatory journals, 99 open access, and 100 subscription-based journals were analyzed; exclusions were due to website unavailability. Many more predatory journals' homepages contained spelling errors (61/93, 66%) and distorted or potentially unauthorized images (59/93, 63%) compared to open access journals (6/99, 6% and 5/99, 5%, respectively) and subscription-based journals (3/100, 3% and 1/100, 1%, respectively). Thirty-one (33%) predatory journals promoted a bogus impact metric - the Index Copernicus Value - versus three (3%) open access journals and no subscription-based journals. Nearly three quarters (n = 66, 73%) of predatory journals had editors or editorial board members whose affiliation with the journal was unverified versus two (2%) open access journals and one (1%) subscription-based journal in which this was the case. Predatory journals charge a considerably smaller publication fee (median $100 USD, IQR $63-$150) than open access journals ($1865 USD, IQR $800-$2205) and subscription-based hybrid journals ($3000 USD, IQR $2500-$3000). We identified 13 evidence-based characteristics by which predatory journals may potentially be distinguished from presumed legitimate journals. These may be useful for authors who are assessing journals for possible submission or for others, such as universities evaluating candidates' publications as part of the hiring process.

Public Access and Open Access: Is There a Difference? | Poster

Cancer.gov

By Robin Meckley, Contributing Writer, and Tracie Frederick, Guest Writer Open access and public access—are they different concepts or are they the same? What do they mean for the researchers at NCI at Frederick? “Open-access (OA) literature is digital, online, free of charge, and free of most copyright and licensing restrictions. What makes it possible is the Internet and the consent of the author or copyright-holder,” according to an open access website maintained by Peter Suber, director, Harvard Open Access Project.

A study of innovative features in scholarly open access journals.

PubMed

Björk, Bo-Christer

2011-12-16

The emergence of the Internet has triggered tremendous changes in the publication of scientific peer-reviewed journals. Today, journals are usually available in parallel electronic versions, but the way the peer-review process works, the look of articles and journals, and the rigid and slow publication schedules have remained largely unchanged, at least for the vast majority of subscription-based journals. Those publishing firms and scholarly publishers who have chosen the more radical option of open access (OA), in which the content of journals is freely accessible to anybody with Internet connectivity, have had a much bigger degree of freedom to experiment with innovations. The objective was to study how open access journals have experimented with innovations concerning ways of organizing the peer review, the format of journals and articles, new interactive and media formats, and novel publishing revenue models. The features of 24 open access journals were studied. The journals were chosen in a nonrandom manner from the approximately 7000 existing OA journals based on available information about interesting journals and include both representative cases and highly innovative outlier cases. Most early OA journals in the 1990s were founded by individual scholars and used a business model based on voluntary work close in spirit to open-source development of software. In the next wave, many long-established journals, in particular society journals and journals from regions such as Latin America, made their articles OA when they started publishing parallel electronic versions. From about 2002 on, newly founded professional OA publishing firms using article-processing charges to fund their operations have emerged. Over the years, there have been several experiments with new forms of peer review, media enhancements, and the inclusion of structured data sets with articles. In recent years, the growth of OA publishing has also been facilitated by the availability of open-source software for journal publishing. The case studies illustrate how a new technology and a business model enabled by new technology can be harnessed to find new innovative ways for the organization and content of scholarly publishing. Several recent launches of OA journals by major subscription publishers demonstrate that OA is rapidly gaining acceptance as a sustainable alternative to subscription-based scholarly publishing.

A Study of Innovative Features in Scholarly Open Access Journals

PubMed Central

2011-01-01

Background The emergence of the Internet has triggered tremendous changes in the publication of scientific peer-reviewed journals. Today, journals are usually available in parallel electronic versions, but the way the peer-review process works, the look of articles and journals, and the rigid and slow publication schedules have remained largely unchanged, at least for the vast majority of subscription-based journals. Those publishing firms and scholarly publishers who have chosen the more radical option of open access (OA), in which the content of journals is freely accessible to anybody with Internet connectivity, have had a much bigger degree of freedom to experiment with innovations. Objective The objective was to study how open access journals have experimented with innovations concerning ways of organizing the peer review, the format of journals and articles, new interactive and media formats, and novel publishing revenue models. Methods The features of 24 open access journals were studied. The journals were chosen in a nonrandom manner from the approximately 7000 existing OA journals based on available information about interesting journals and include both representative cases and highly innovative outlier cases. Results Most early OA journals in the 1990s were founded by individual scholars and used a business model based on voluntary work close in spirit to open-source development of software. In the next wave, many long-established journals, in particular society journals and journals from regions such as Latin America, made their articles OA when they started publishing parallel electronic versions. From about 2002 on, newly founded professional OA publishing firms using article-processing charges to fund their operations have emerged. Over the years, there have been several experiments with new forms of peer review, media enhancements, and the inclusion of structured data sets with articles. In recent years, the growth of OA publishing has also been facilitated by the availability of open-source software for journal publishing. Conclusions The case studies illustrate how a new technology and a business model enabled by new technology can be harnessed to find new innovative ways for the organization and content of scholarly publishing. Several recent launches of OA journals by major subscription publishers demonstrate that OA is rapidly gaining acceptance as a sustainable alternative to subscription-based scholarly publishing. PMID:22173122

Low-temperature bonding process for the fabrication of hybrid glass-membrane organ-on-a-chip devices

NASA Astrophysics Data System (ADS)

Pocock, Kyall J.; Gao, Xiaofang; Wang, Chenxi; Priest, Craig; Prestidge, Clive A.; Mawatari, Kazuma; Kitamori, Takehiko; Thierry, Benjamin

2016-10-01

The integration of microfluidics with living biological systems has paved the way to the exciting concept of "organs-on-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 utilized in the field of microfluidics but the integration of alternative functional elements within multilayered 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 optimized 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 h, 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.

50 CFR 660.316 - Open access fishery-observer requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Open access fishery-observer requirements. 660.316 Section 660.316 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC... West Coast Groundfish-Open Access Fisheries § 660.316 Open access fishery—observer requirements. (a...

50 CFR 660.316 - Open access fishery-observer requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Open access fishery-observer requirements. 660.316 Section 660.316 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC... West Coast Groundfish-Open Access Fisheries § 660.316 Open access fishery—observer requirements. (a...

50 CFR 660.316 - Open access fishery-observer requirements.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Open access fishery-observer requirements. 660.316 Section 660.316 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC... West Coast Groundfish-Open Access Fisheries § 660.316 Open access fishery—observer requirements. (a...

50 CFR 660.316 - Open access fishery-observer requirements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Open access fishery-observer requirements. 660.316 Section 660.316 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC... West Coast Groundfish-Open Access Fisheries § 660.316 Open access fishery—observer requirements. (a...

50 CFR 660.316 - Open access fishery-observer requirements.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Open access fishery-observer requirements. 660.316 Section 660.316 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC... West Coast Groundfish-Open Access Fisheries § 660.316 Open access fishery—observer requirements. (a...

An evaluation of emergency medicine investigators' views on open access to medical literature.

PubMed

Rodriguez, R M; Wong, J; Hardy, J; Frankel, E

2006-12-01

Scientists and governmental agencies have called for free universal access to research publications via the internet--open access. To examine the current medical literature reading practices of emergency medicine investigators (EMIs) and their views towards open access. Surveys were mailed to the 212 corresponding authors of all original research articles published in years 2002 and 2003 in the Annals of Emergency Medicine, Academic Emergency Medicine and The Journal of Emergency Medicine. The most commonly read forms of medical literature reported by the 129 (61%) EMI respondents were hard-copy medical journals and online literature review services. 59% of EMIs were in favour of open access; 58% stated they would read a wider variety of medical literature; 21% believed open access would improve the quality of publications and 39% thought it would decrease the quality. When asked how a US 1500 dollars fee for open access would affect their ability to publish research, 69% said it would greatly impede and 19% said it would slightly impede their research. Despite concerns that open access may impede their ability to publish research and decrease the quality of publications, most EMIs surveyed favoured open access. They believed open access would increase and broaden their medical literature reading.

Gas flow in plant microfluidic networks controlled by capillary valves

NASA Astrophysics Data System (ADS)

Capron, M.; Tordjeman, Ph.; Charru, F.; Badel, E.; Cochard, H.

2014-03-01

The xylem vessels of trees constitute a model natural microfluidic system. In this work, we have studied the mechanism of air flow in the Populus xylem. The vessel microstructure was characterized by optical microscopy, transmission electronic microscopy (TEM), and atomic force microscopy (AFM) at different length scales. The xylem vessels have length ≈15 cm and diameter ≈20μm. Flow from one vessel to the next occurs through ˜102 pits, which are grouped together at the ends of the vessels. The pits contain a thin, porous pit membrane with a thickness of 310 nm. We have measured the Young's moduli of the vessel wall and of the pits (both water-saturated and after drying) by specific nanoindentation and nanoflexion experiments with AFM. We found that both the dried and water-saturated pit membranes have Young's modulus around 0.4 MPa, in agreement with values obtained by micromolding of pits deformed by an applied pressure difference. Air injection experiments reveal that air flows through the xylem vessels when the differential pressure across a sample is larger than a critical value ΔPc=1.8 MPa. In order to model the air flow rate for ΔP ⩾ΔPc, we assumed the pit membrane to be a porous medium that is strained by the applied pressure difference. Water menisci in the pit pores play the role of capillary valves, which open at ΔP =ΔPc. From the point of view of the plant physiology, this work presents a basic understanding of the physics of bordered pits.

Microfluidic Injector Models Based on Artificial Neural Networks

DTIC Science & Technology

2005-06-15

medicine, and chemistry [1], [2]. They generally perform chemical analysis involving sample preparation, mixing , reaction, injection, separation analysis...algorithms have been validated against many ex- periments found in the literature demonstrating microfluidic mixing , joule heating, injection, and...385 [7] K. Seiler, Z. H. Fan, K. Fluri, and D. J. Harrison, “ Electroosmotic pump- ing and valveless control of fluid flow within a manifold of

The GeoDataPortal: A Standards-based Environmental Modeling Data Access and Manipulation Toolkit

NASA Astrophysics Data System (ADS)

Blodgett, D. L.; Kunicki, T.; Booth, N.; Suftin, I.; Zoerb, R.; Walker, J.

2010-12-01

Environmental modelers from fields of study such as climatology, hydrology, geology, and ecology rely on many data sources and processing methods that are common across these disciplines. Interest in inter-disciplinary, loosely coupled modeling and data sharing is increasing among scientists from the USGS, other agencies, and academia. For example, hydrologic modelers need downscaled climate change scenarios and land cover data summarized for the watersheds they are modeling. Subsequently, ecological modelers are interested in soil moisture information for a particular habitat type as predicted by the hydrologic modeler. The USGS Center for Integrated Data Analytics Geo Data Portal (GDP) project seeks to facilitate this loose model coupling data sharing through broadly applicable open-source web processing services. These services simplify and streamline the time consuming and resource intensive tasks that are barriers to inter-disciplinary collaboration. The GDP framework includes a catalog describing projects, models, data, processes, and how they relate. Using newly introduced data, or sources already known to the catalog, the GDP facilitates access to sub-sets and common derivatives of data in numerous formats on disparate web servers. The GDP performs many of the critical functions needed to summarize data sources into modeling units regardless of scale or volume. A user can specify their analysis zones or modeling units as an Open Geospatial Consortium (OGC) standard Web Feature Service (WFS). Utilities to cache Shapefiles and other common GIS input formats have been developed to aid in making the geometry available for processing via WFS. Dataset access in the GDP relies primarily on the Unidata NetCDF-Java library’s common data model. Data transfer relies on methods provided by Unidata’s Thematic Real-time Environmental Data Distribution System Data Server (TDS). TDS services of interest include the Open-source Project for a Network Data Access Protocol (OPeNDAP) standard for gridded time series, the OGC’s Web Coverage Service for high-density static gridded data, and Unidata’s CDM-remote for point time series. OGC WFS and Sensor Observation Service (SOS) are being explored as mechanisms to serve and access static or time series data attributed to vector geometry. A set of standardized XML-based output formats allows easy transformation into a wide variety of “model-ready” formats. Interested users will have the option of submitting custom transformations to the GDP or transforming the XML output as a post-process. The GDP project aims to support simple, rapid development of thin user interfaces (like web portals) to commonly needed environmental modeling-related data access and manipulation tools. Standalone, service-oriented components of the GDP framework provide the metadata cataloging, data subset access, and spatial-statistics calculations needed to support interdisciplinary environmental modeling.

Collaborative development of predictive toxicology applications

PubMed Central

2010-01-01

OpenTox provides an interoperable, standards-based Framework for the support of predictive toxicology data management, algorithms, modelling, validation and reporting. It is relevant to satisfying the chemical safety assessment requirements of the REACH legislation as it supports access to experimental data, (Quantitative) Structure-Activity Relationship models, and toxicological information through an integrating platform that adheres to regulatory requirements and OECD validation principles. Initial research defined the essential components of the Framework including the approach to data access, schema and management, use of controlled vocabularies and ontologies, architecture, web service and communications protocols, and selection and integration of algorithms for predictive modelling. OpenTox provides end-user oriented tools to non-computational specialists, risk assessors, and toxicological experts in addition to Application Programming Interfaces (APIs) for developers of new applications. OpenTox actively supports public standards for data representation, interfaces, vocabularies and ontologies, Open Source approaches to core platform components, and community-based collaboration approaches, so as to progress system interoperability goals. The OpenTox Framework includes APIs and services for compounds, datasets, features, algorithms, models, ontologies, tasks, validation, and reporting which may be combined into multiple applications satisfying a variety of different user needs. OpenTox applications are based on a set of distributed, interoperable OpenTox API-compliant REST web services. The OpenTox approach to ontology allows for efficient mapping of complementary data coming from different datasets into a unifying structure having a shared terminology and representation. Two initial OpenTox applications are presented as an illustration of the potential impact of OpenTox for high-quality and consistent structure-activity relationship modelling of REACH-relevant endpoints: ToxPredict which predicts and reports on toxicities for endpoints for an input chemical structure, and ToxCreate which builds and validates a predictive toxicity model based on an input toxicology dataset. Because of the extensible nature of the standardised Framework design, barriers of interoperability between applications and content are removed, as the user may combine data, models and validation from multiple sources in a dependable and time-effective way. PMID:20807436

Collaborative development of predictive toxicology applications.

PubMed

Hardy, Barry; Douglas, Nicki; Helma, Christoph; Rautenberg, Micha; Jeliazkova, Nina; Jeliazkov, Vedrin; Nikolova, Ivelina; Benigni, Romualdo; Tcheremenskaia, Olga; Kramer, Stefan; Girschick, Tobias; Buchwald, Fabian; Wicker, Joerg; Karwath, Andreas; Gütlein, Martin; Maunz, Andreas; Sarimveis, Haralambos; Melagraki, Georgia; Afantitis, Antreas; Sopasakis, Pantelis; Gallagher, David; Poroikov, Vladimir; Filimonov, Dmitry; Zakharov, Alexey; Lagunin, Alexey; Gloriozova, Tatyana; Novikov, Sergey; Skvortsova, Natalia; Druzhilovsky, Dmitry; Chawla, Sunil; Ghosh, Indira; Ray, Surajit; Patel, Hitesh; Escher, Sylvia

2010-08-31

OpenTox provides an interoperable, standards-based Framework for the support of predictive toxicology data management, algorithms, modelling, validation and reporting. It is relevant to satisfying the chemical safety assessment requirements of the REACH legislation as it supports access to experimental data, (Quantitative) Structure-Activity Relationship models, and toxicological information through an integrating platform that adheres to regulatory requirements and OECD validation principles. Initial research defined the essential components of the Framework including the approach to data access, schema and management, use of controlled vocabularies and ontologies, architecture, web service and communications protocols, and selection and integration of algorithms for predictive modelling. OpenTox provides end-user oriented tools to non-computational specialists, risk assessors, and toxicological experts in addition to Application Programming Interfaces (APIs) for developers of new applications. OpenTox actively supports public standards for data representation, interfaces, vocabularies and ontologies, Open Source approaches to core platform components, and community-based collaboration approaches, so as to progress system interoperability goals.The OpenTox Framework includes APIs and services for compounds, datasets, features, algorithms, models, ontologies, tasks, validation, and reporting which may be combined into multiple applications satisfying a variety of different user needs. OpenTox applications are based on a set of distributed, interoperable OpenTox API-compliant REST web services. The OpenTox approach to ontology allows for efficient mapping of complementary data coming from different datasets into a unifying structure having a shared terminology and representation.Two initial OpenTox applications are presented as an illustration of the potential impact of OpenTox for high-quality and consistent structure-activity relationship modelling of REACH-relevant endpoints: ToxPredict which predicts and reports on toxicities for endpoints for an input chemical structure, and ToxCreate which builds and validates a predictive toxicity model based on an input toxicology dataset. Because of the extensible nature of the standardised Framework design, barriers of interoperability between applications and content are removed, as the user may combine data, models and validation from multiple sources in a dependable and time-effective way.

Structuring Legacy Pathology Reports by openEHR Archetypes to Enable Semantic Querying.

PubMed

Kropf, Stefan; Krücken, Peter; Mueller, Wolf; Denecke, Kerstin

2017-05-18

Clinical information is often stored as free text, e.g. in discharge summaries or pathology reports. These documents are semi-structured using section headers, numbered lists, items and classification strings. However, it is still challenging to retrieve relevant documents since keyword searches applied on complete unstructured documents result in many false positive retrieval results. We are concentrating on the processing of pathology reports as an example for unstructured clinical documents. The objective is to transform reports semi-automatically into an information structure that enables an improved access and retrieval of relevant data. The data is expected to be stored in a standardized, structured way to make it accessible for queries that are applied to specific sections of a document (section-sensitive queries) and for information reuse. Our processing pipeline comprises information modelling, section boundary detection and section-sensitive queries. For enabling a focused search in unstructured data, documents are automatically structured and transformed into a patient information model specified through openEHR archetypes. The resulting XML-based pathology electronic health records (PEHRs) are queried by XQuery and visualized by XSLT in HTML. Pathology reports (PRs) can be reliably structured into sections by a keyword-based approach. The information modelling using openEHR allows saving time in the modelling process since many archetypes can be reused. The resulting standardized, structured PEHRs allow accessing relevant data by retrieving data matching user queries. Mapping unstructured reports into a standardized information model is a practical solution for a better access to data. Archetype-based XML enables section-sensitive retrieval and visualisation by well-established XML techniques. Focussing the retrieval to particular sections has the potential of saving retrieval time and improving the accuracy of the retrieval.

Ubiquitous information for ubiquitous computing: expressing clinical data sets with openEHR archetypes.

PubMed

Garde, Sebastian; Hovenga, Evelyn; Buck, Jasmin; Knaup, Petra

2006-01-01

Ubiquitous computing requires ubiquitous access to information and knowledge. With the release of openEHR Version 1.0 there is a common model available to solve some of the problems related to accessing information and knowledge by improving semantic interoperability between clinical systems. Considerable work has been undertaken by various bodies to standardise Clinical Data Sets. Notwithstanding their value, several problems remain unsolved with Clinical Data Sets without the use of a common model underpinning them. This paper outlines these problems like incompatible basic data types and overlapping and incompatible definitions of clinical content. A solution to this based on openEHR archetypes is motivated and an approach to transform existing Clinical Data Sets into archetypes is presented. To avoid significant overlaps and unnecessary effort during archetype development, archetype development needs to be coordinated nationwide and beyond and also across the various health professions in a formalized process.

Brokered virtual hubs for facilitating access and use of geospatial Open Data

NASA Astrophysics Data System (ADS)

Mazzetti, Paolo; Latre, Miguel; Kamali, Nargess; Brumana, Raffaella; Braumann, Stefan; Nativi, Stefano

2016-04-01

Open Data is a major trend in current information technology scenario and it is often publicised as one of the pillars of the information society in the near future. In particular, geospatial Open Data have a huge potential also for Earth Sciences, through the enablement of innovative applications and services integrating heterogeneous information. However, open does not mean usable. As it was recognized at the very beginning of the Web revolution, many different degrees of openness exist: from simple sharing in a proprietary format to advanced sharing in standard formats and including semantic information. Therefore, to fully unleash the potential of geospatial Open Data, advanced infrastructures are needed to increase the data openness degree, enhancing their usability. In October 2014, the ENERGIC OD (European NEtwork for Redistributing Geospatial Information to user Communities - Open Data) project, funded by the European Union under the Competitiveness and Innovation framework Programme (CIP), has started. In response to the EU call, the general objective of the project is to "facilitate the use of open (freely available) geographic data from different sources for the creation of innovative applications and services through the creation of Virtual Hubs". The ENERGIC OD Virtual Hubs aim to facilitate the use of geospatial Open Data by lowering and possibly removing the main barriers which hampers geo-information (GI) usage by end-users and application developers. Data and services heterogeneity is recognized as one of the major barriers to Open Data (re-)use. It imposes end-users and developers to spend a lot of effort in accessing different infrastructures and harmonizing datasets. Such heterogeneity cannot be completely removed through the adoption of standard specifications for service interfaces, metadata and data models, since different infrastructures adopt different standards to answer to specific challenges and to address specific use-cases. Thus, beyond a certain extent, heterogeneity is irreducible especially in interdisciplinary contexts. ENERGIC OD Virtual Hubs address heterogeneity adopting a mediation and brokering approach: specific components (brokers) are dedicated to harmonize service interfaces, metadata and data models, enabling seamless discovery and access to heterogeneous infrastructures and datasets. As an innovation project, ENERGIC OD integrates several existing technologies to implement Virtual Hubs as single points of access to geospatial datasets provided by new or existing platforms and infrastructures, including INSPIRE-compliant systems and Copernicus services. A first version of the ENERGIC OD brokers has been implemented based on the GI-Suite Brokering Framework developed by CNR-IIA, and complemented with other tools under integration and development. It already enables mediated discovery and harmonized access to different geospatial Open Data sources. It is accessible by users as Software-as-a-Service through a browser. Moreover, open APIs and a Javascript library are available for application developers. Six ENERGIC OD Virtual Hubs have been currently deployed: one at regional level (Berlin metropolitan area) and five at national-level (in France, Germany, Italy, Poland and Spain). Each Virtual Hub manager decided the deployment strategy (local infrastructure or commercial Infrastructure-as-a-Service cloud), and the list of connected Open Data sources. The ENERGIC OD Virtual Hubs are under test and validation through the development of ten different mobile and Web applications.

Open Access Alternatives

ERIC Educational Resources Information Center

Tenopir, Carol

2004-01-01

Open access publishing is a hot topic today. But open access publishing can have many different definitions, and pros and cons vary with the definitions. Open access publishing is especially attractive to companies and small colleges or universities that are likely to have many more readers than authors. A downside is that a membership fee sounds…

50 CFR 648.88 - Multispecies open access permit restrictions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 10 2011-10-01 2011-10-01 false Multispecies open access permit... Management Measures for the NE Multispecies and Monkfish Fisheries § 648.88 Multispecies open access permit restrictions. (a) Handgear permit. A vessel issued a valid open access NE multispecies Handgear permit is...

50 CFR 648.88 - Multispecies open access permit restrictions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Multispecies open access permit... Management Measures for the NE Multispecies and Monkfish Fisheries § 648.88 Multispecies open access permit restrictions. (a) Handgear permit. A vessel issued a valid open access NE multispecies Handgear permit is...

50 CFR 660.383 - Open access fishery management measures.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Open access fishery management measures... West Coast Groundfish Fisheries § 660.383 Open access fishery management measures. (a) General. Groundfish species taken in open access fisheries will be managed with cumulative trip limits (see trip...

50 CFR 648.88 - Multispecies open access permit restrictions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Multispecies open access permit... Management Measures for the NE Multispecies and Monkfish Fisheries § 648.88 Multispecies open access permit restrictions. (a) Handgear permit. A vessel issued a valid open access NE multispecies Handgear permit is...

50 CFR 648.88 - Multispecies open access permit restrictions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Multispecies open access permit... Management Measures for the NE Multispecies and Monkfish Fisheries § 648.88 Multispecies open access permit restrictions. (a) Handgear permit. A vessel issued a valid open access NE multispecies Handgear permit is...