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Sample records for evanescent cell sensors

  1. Polymer photonic crystal dye lasers as label free evanescent cell sensors

    NASA Astrophysics Data System (ADS)

    Christiansen, Mads B.; Lopacinska, Joanna M.; Jakobsen, Mogens H.; Mortensen, Niels A.; Dufva, Martin; Kristensen, Anders

    2009-08-01

    Dye doped polymer photonic crystal band edge lasers are applied for evanescent wave sensing of cells. The lasers are rectangular shaped slab waveguides of dye doped polymer on a glass substrate, where a photonic crystal is formed by 100 nm deep air-holes in the surface of the 375 nm high waveguides. The lasers are fabricated by combined nanoimprint and photolithography (CNP) in Ormocore hybrid polymer doped with the laser dye Pyrromethene 597. The lasers emit in the chip plane at a wavelength around 595 nm when pumped with 5 ns pulses from a compact frequency doubled Nd:YAG laser. We investigate the sensitivity of photonic crystal band-edge lasers to partial coverage with HeLa cells. The lasers are chemically activated with a flexible UV activated anthraquinone based linker molecule, which enables selective binding of cells and molecules. When measuring in Phosphate Buffered Saline (PBS), which has a refractive index close to that of the cells, the emission wavelength depends linearly on the cell density on the sensor surface. Our results demonstrate that nanostructured hybrid polymer lasers, which are cheap to fabricate and very simple to operate, can be selectively chemically activated with UV sensitive photolinkers for further bioanalytical applications. This opens the possibility to functionalize arrays of optofluidic laser sensors with different bio-recognition molecules for multiplexed sensing. The linear relationship between cell coverage and wavelength indicates that the slight refractive index perturbation from the partial coverage of the sensor influences the entire optical mode, rather than breaking down the photonic crystal feedback.

  2. Reversible evanescent wave sensors for hydrazine

    NASA Astrophysics Data System (ADS)

    Carter, Michael T.; Smith, Jimmy R.; Mowry, Donald R.; Patel, Jay G.

    1999-02-01

    We report recent progress on development of evanescent wave fiber optic sensors for hydrazine (HZ), monomethylhydrazine (MMH) and unsymmetrical dimethylhydrazine (UDMH). Chemically reversible evanescent sensors capable of detection below 10 ppb were prepared by removing cladding from commercial multimode fiber and coating the exposed core with a hydrazine-sensitive triphenylmethane dye immobilized in an inert polymer matrix, typically poly(vinylchloride). Triphenylmethane dyes bleach reversibly in the presence of hydrazines, enabling colorimetric sensing. The linear dynamic range was typically 0 - 300 ppb and overall dynamic range up to ca. 5 ppm. Sensors optimized for HZ were as much as a factor of 45 less sensitive to MMH and UDMH, suggesting that the sensor film would require optimization for each analyte. Saturation response and relaxation times were on the order of 5 - 8 min, but measurable signals for 10 ppb HZ could be obtained in under 30 s. These sensors demonstrate a novel route to reversible sensing of these highly toxic compounds.

  3. Improved structures for evanescent wave sensors

    NASA Astrophysics Data System (ADS)

    Rehouma, F.; Elflein, W.; Persegol, D.; Kevorkian, A.; Clauss, G.; Benech, P.; Rimet, R.

    1995-03-01

    Integrated optics evanescent wave sensors suffer from attenuation losses and reduced contrast ratio when the sensing layer index is too close to the waveguide index. This is attributed to an increase in mode mismatch at inner interfaces of the devices. By properly balancing the losses on each arm of an integrated Mach-Zehnder the contrast ratio is increased to nearly 100% on the entire index range, furthermore, a new technique used to make a smooth transition between sensing and nonsensing waveguides reduced the losses by 5 dB.

  4. Approaches from a single- to a multiparameter evanescent wave sensor

    NASA Astrophysics Data System (ADS)

    Bock, Daniel; Hartmann, Andreas; Kaul, Sepp; Martin, Michael; Schulz, V.; Wolfrum, Juergen M.; Seeger, Stefan

    1996-01-01

    Evanescent wave sensors are an interesting tool for the fast detection of reactions between biomolecules. By using small and inexpensive diode lasers together with fluorescent dyes in the red spectral region, it was possible to construct a highly specific sensor. This was due to the use of the immobilization of receptor molecules via the Langmuir-Blodgett technique which enhances the specificity drastically. As a clinically relevant system an immunoassay of the tumor marker mucine was investigated. Mucine could be detected with a sandwich test using the antibody system BM-2/BM-7. In order to detect several analytes at one time, there are two possible ways: time-resolved detection using multiplex-dyes and the parallelization of the sensor by using several fibers simultaneously. A position-resolved evanescent wave sensor using a CCD camera is described.

  5. Evanescent field sensors and the implementation of waveguiding nanostructures

    SciTech Connect

    Boerner, Sandra; Orghici, Rozalia; Waldvogel, Siegfried R.; Willer, Ulrike; Schade, Wolfgang

    2009-02-01

    Conventional fiber optic evanescent-field gas sensors are based on a high number of total reflections while the gas is passing the active bare core fiber and of course a suitable laser light source. The use of miniaturized laser sources for sensitive detection of CO2 in gaseous and water-dissolved phase for environmental monitoring are studied for signal enhancing purposes. Additionally, the fiber optic sensor, consisting of a coiled bare multimode fiber core, was sensitized by an active polymer coating for the detection of explosive TNT. The implementation of ZnO waveguiding nanowires is discussed for surface and sensitivity enhancing coating of waveguiding elements, considering computational and experimental results.

  6. Planar Optical Sensors and Evanescent Wave Effects

    NASA Astrophysics Data System (ADS)

    Burke, Conor S.; Stránik, Ondrej; McEvoy, Helen M.; MacCraith, Brian D.

    Recent developments in microsystems technology have led to the widespread application of microfabrication techniques for the production of sensor platforms. These techniques have had a major impact on the development of so-called "Lab-on-a-Chip" devices. The major application areas for theses devices are biomedical diagnostics, industrial process monitoring, environmental monitoring, drug discovery, and defence. In the context of biomedical diagnostic applications, for example, such devices are intended to provide quantitative chemical or biochemical information on samples such as blood, sweat and saliva while using minimal sample volume.

  7. Evanescent-wave spectroscopic fiber optic pH sensor

    NASA Astrophysics Data System (ADS)

    Egami, C.; Takeda, K.; Isai, M.; Ogita, M.

    1996-02-01

    We demonstrate a new type of fiber optic pH sensor, which is the application of evanescent-wave spectroscopic technique. A methyl red (MR)-doped-poly(methyl methacrylate) (PMMA) film that coated as part of cladding does function as a pH sensor probe. In this system MR doped in PMMA is used as indicator dye for pH measurement. The absorption spectrum shift in wavelength of indicator dye enables us to get the pH value. The sensor probe is immersed in water solution containing a small proportion of acetic acid over the wide pH range of 5.0 to 7.0. The chemical interaction between MR in sensor probe and hydrogen ion in the water solution causes a change in the dipole moment of MR, that is, the absorption spectrum macroscopically. The evanescent-wave spectroscopic technique provides the measurement of the absorption spectrum shift over a broad range of visible wavelength. The result of experiment was that MR absorption spectrum shifted by 40 nm every increase of 1.0 in pH. The small change in the pH value can be sensed as a large wavelength shift of pH indicator absorption spectrum.

  8. Melamine sensing based on evanescent field enhanced optical fiber sensor

    NASA Astrophysics Data System (ADS)

    Luo, Ji; Yao, Jun; Wang, Wei-min; Zhuang, Xu-ye; Ma, Wen-ying; Lin, Qiao

    2013-08-01

    Melamine is an insalubrious chemical, and has been frequently added into milk products illegally, to make the products more protein-rich. However, it can cause some various diseases, such as kidney stones and bladder cancer. In this paper, a novel optical fiber sensor with high sensitivity based on absorption of the evanescent field for melamine detection is successfully proposed and developed. Different concentrations of melamine changing from 0 to 10mg/mL have been detected using the micro/nano-sensing fiber decorated with silver nanoparticles cluster layer. As the concentration increases, the sensing fiber's output intensity gradually deceases and the absorption of the analyte becomes large. The concentration changing of 1mg/ml can cause the absorbance varying 0.664 and the limit of the melamine detectable concentration is 1ug/mL. Besides, the coupling properties between silver nanoparticles have also been analyzed by the FDTD method. Overall, this evanescent field enhanced optical fiber sensor has potential to be used in oligo-analyte detection and will promote the development of biomolecular and chemical sensing applications.

  9. Fiber optic evanescent wave (FOEW) microbial sensor for dental application

    NASA Astrophysics Data System (ADS)

    Kishen, Anil; John, M. S.; Chen, Jun-Wei; Lim, Chu S.; Hu, Xiao; Asundi, Anand K.

    2001-10-01

    In this work a new approach based on the fiber Optic Evanescent Wave (FOEW) Spectroscopy is developed for the effective determination of dental caries activity in human saliva. The biosensor design utilized the exponentially decaying wave that extends to the lower index region of the optical fiber's core-cladding interface. In order to achieve this, a short length of the cladding is removed and the fiber core surface is coated with a porous glass medium using sol-gel technique. The acidogenic profile resulting from the Streptococcus mutans activity in the human saliva is monitored using an indicator, which was encapsulated within the porous coating. These investigations display the potential benefits of FOEW based microbial sensor to monitor caries activity in human saliva.

  10. Chemical detection demonstrated using an evanescent wave graphene optical sensor

    NASA Astrophysics Data System (ADS)

    Maliakal, Ashok; Reith, Leslie; Cabot, Steve

    2016-04-01

    Graphene devices have been constructed on silicon mirrors, and the graphene is optically probed through an evanescent wave interaction in an attenuated total reflectance configuration using an infrared spectrometer. The graphene is electrically biased in order to tune its optical properties. Exposure of the device to the chemicals iodine and ammonia causes observable and reversible changes to graphene's optical absorption spectra in the mid to near infrared range which can be utilized for the purpose of sensing. Electrical current measurements through the graphene are made simultaneously with optical measurements allowing for simultaneous sensing using two separate detection modalities. Our current results reveal sub-ppm detection limits for iodine and approximately 100 ppm detection limits for ammonia. We have also demonstrated that this approach will work at 1.55 μm, which opens up the possibility for graphene optical sensors that leverage commercial telecom light sources.

  11. Theory of fiber-optic, evanescent-wave spectroscopy and sensors

    NASA Astrophysics Data System (ADS)

    Messica, A.; Greenstein, A.; Katzir, A.

    1996-05-01

    A general theory for fiber-optic, evanescent-wave spectroscopy and sensors is presented for straight, uncladded, step-index, multimode fibers. A three-dimensional model is formulated within the framework of geometric optics. The model includes various launching conditions, input and output end-face Fresnel transmission losses, multiple Fresnel reflections, bulk absorption, and evanescent-wave absorption. An evanescent-wave sensor response is analyzed as a function of externally controlled parameters such as coupling angle, f number, fiber length, and diameter. Conclusions are drawn for several experimental apparatuses.

  12. A microvolume molecularly imprinted polymer modified fiber-optic evanescent wave sensor for bisphenol A determination.

    PubMed

    Xiong, Yan; Ye, Zhongbin; Xu, Jing; Liu, Yucheng; Zhang, Hanyin

    2014-04-01

    A fiber-optic evanescent wave sensor for bisphenol A (BPA) determination based on a molecularly imprinted polymer (MIP)-modified fiber column was developed. MIP film immobilized with BPA was synthesized on the fiber column, and the sensor was then constructed by inserting the optical fiber prepared into a transparent capillary. A microchannel (about 2.0 μL) formed between the fiber and the capillary acted as a flow cell. BPA can be selectively adsorbed online by the MIP film and excited to produce fluorescence by the evanescent wave produced on the fiber core surface. The conditions for BPA enrichment, elution, and fluorescence detection are discussed in detail. The analytical measurements were made at 276 nm/306 nm (λ(ex)/λ(em)), and linearity of 3 × 10(-9)-5 × 10(-6) g mL(-1) BPA, a limit of detection of 1.7 × 10(-9) g mL(-1) BPA (3σ), and a relative standard deviation of 2.4% (n = 5) were obtained. The sensor selectivity and MIP binding measurement were also evaluated. The results indicated that the selectivity and sensitivity of the proposed fiber-optic sensor could be greatly improved by using MIP as a recognition and enrichment element. Further, by modification of the sensing and detection elements on the optical fiber, the proposed sensor showed the advantages of easy fabrication and low cost. The novel sensor configuration provided a platform for monitoring other species by simply changing the light source and sensing elements. The sensor presented has been successfully applied to determine BPA released from plastic products treated at different temperatures.

  13. Theoretical and experimental investigation of evanescent-wave absorption sensors for extreme temperature applications

    NASA Astrophysics Data System (ADS)

    Buric, Michael P.; Ohodnicki, Paul; Chorpening, Benjamin

    2013-09-01

    Recently, significant developments in evanescent wave absorption sensors have been demonstrated for high temperature sensing applications based upon the optical responses of advanced thin film materials. We will demonstrate how such sensors can be utilized in a mode that allows for chemical or temperature sensing starting from basic theoretical considerations. We will also present experimental high temperature sensing results for fabricated sensors. Potential applications of the sensors to be discussed include a range of high temperature systems relevant for fossil energy and combustion monitoring such as industrial combustors or reaction vessels, solid oxide fuel cells, and gas turbines. In these applications, even a small increase in operating efficiency realized via careful observation of in-process parameters and implementation of real-time process controls can result in dramatic savings across the energy industry, illustrating the necessity of pursuing such techniques. It is hoped that sensors of the type described here will allow for unprecedented measurement-access to processes which present challenging high-temperature and chemically reactive environments.

  14. Determination of bacterial activity by use of an evanescent-wave fiber-optic sensor

    NASA Astrophysics Data System (ADS)

    John, M. Shelly; Kishen, Anil; Sing, Lim Chu; Asundi, Anand

    2002-12-01

    A novel technique based on fiber-optic evanescent-wave spectroscopy is proposed for the detection of bacterial activity in human saliva. The sensor determines the specific concentration of Streptococcus mutans in saliva, which is a major causative factor in dental caries. In this design, one prepares the fiber-optic bacterial sensor by replacing a portion of the cladding region of a multimode fiber with a dye-encapsulated xerogel, using the solgel technique. The exponential decay of the evanescent wave at the core-cladding interface of a multimode fiber is utilized for the determination of bacterial activity in saliva. The acidogenic profile of Streptococcus mutans is estimated by use of evanescent-wave absorption spectra at various levels of bacterial activity.

  15. Biochemical fiber sensor based on evanescent field for detection persistent organic pollutants (POPs)

    NASA Astrophysics Data System (ADS)

    Prasetyo, Edi; Putri Gitrin, Martia; Marzuki, Ahmad; Suryanti, Venty

    2017-01-01

    Fiber optic is a light waveguides media that are cylindrical. Optical fiber has certain properties when it transmits light so it can be developed to be a sensing device or sensor. Evanescent wave phenomena appear when there are total internal reflections from many modes in an optical fiber. In this research, the Biochemical Fiber Sensor (BFS) using polishing cladding and some of the core fiber will be fabricated. BFS is used to interact with a biochemical compound. The principle of BFS is based on evanescent absorption which absorbs the typical spectrum of a biochemical compound. By measuring the spectrum from the light output in the BFS, evanescent absorption spectra can be analyzed an optical fiber. In this study, the biochemical compounds that used are lindane that is one of the Persistent Organic Pollutants (POPs). The result showed that there is a change from BFS spectra when it was exposed by POPs compound with various concentration. That change showed that there is evanescent absorption in BFS. Concentration of POPs compound is proportional with evanescent absorption of the POPs compound.

  16. Waveguide evanescent field fluorescence microscopy & its application in cell biology

    NASA Astrophysics Data System (ADS)

    Hassanzadeh, Abdollah

    There are many powerful microscopy technologies available for the investigation of bulk materials as well as for thin film samples. Nevertheless, for imaging an interface, especially live cells on a substrate and ultra thin-films, only Total Internal Reflection Fluorescence (TIRF) microscopy is available. This TIRF microscopy allows imaging without interference of the bulk. Various approaches are employed in fluorescence microscopy applications to restrict the excitation and detection of fluorophores to a thin region of the specimen. Elimination of background fluorescence from outside the focal plane can dramatically improve the signal-to-noise ratio, and consequently, the spatial resolution of the features or events of interest. TIRF microscopy is an evanescent field based microscopy. In this method, fluorescent dyes are only excited within an evanescent field: roughly within 100 nm above a glass coverslip. This will allow imaging surface and interfacial issues of the glass coverslip and an adjacent material. Waveguide evanescent field fluorescence (WEFF) microscopy is a new development for imaging cell-substrate interactions in real time and in vitro. It is an alternative to TIRF microscopy. In this method the light is coupled into a waveguide via an optical grating. The coupled light propagates as a waveguide mode and exhibits an evanescent field on top of the waveguide. This can be used as a surface-bound illumination source to excite fluorophores. This evanescent field serves as an extremely powerful tool for quality control of thin films, to study cell-substrate contacts, and investigating the effect of external agents and drugs on the cell-substrate interaction in real time and in vitro. This new method has been established and optimized to minimize non-uniformity, scattering and photo bleaching issues. Visualizing and quantifying of the cell-substrates and solid thin films have been carried out by WEFF microscopy. The images of the cell-substrate interface

  17. Design method for a distributed Bragg resonator based evanescent field sensor

    NASA Astrophysics Data System (ADS)

    Bischof, David; Kehl, Florian; Michler, Markus

    2016-12-01

    This paper presents an analytic design method for a distributed Bragg resonator based evanescent field sensor. Such sensors can, for example, be used to measure changing refractive indices of the cover medium of a waveguide, as well as molecule adsorption at the sensor surface. For given starting conditions, the presented design method allows the analytical calculation of optimized sensor parameters for quantitative simulation and fabrication. The design process is based on the Fabry-Pérot resonator and analytical solutions of coupled mode theory.

  18. Evanescent field Sensors Based on Tantalum Pentoxide Waveguides – A Review

    PubMed Central

    Schmitt, Katrin; Oehse, Kerstin; Sulz, Gerd; Hoffmann, Christian

    2008-01-01

    Evanescent field sensors based on waveguide surfaces play an important role where high sensitivity is required. Particularly tantalum pentoxide (Ta2O5) is a suitable material for thin-film waveguides due to its high refractive index and low attenuation. Many label-free biosensor systems such as grating couplers and interferometric sensors as well as fluorescence-based systems benefit from this waveguide material leading to extremely high sensitivity. Some biosensor systems based on Ta2O5 waveguides already took the step into commercialization. This report reviews the various detection systems in terms of limit of detection, the applications, and the suitable surface chemistry. PMID:27879731

  19. A Silver Nanoparticle-Modified Evanescent Field Optical Fiber Sensor for Methylene Blue Detection

    PubMed Central

    Luo, Ji; Yao, Jun; Lu, Yonggang; Ma, Wenying; Zhuang, Xuye

    2013-01-01

    A silver nanoparticle-modified evanescent field optical fiber sensor based on a MEMS microchannel chip has been successfully fabricated. Experimental results show that the sensor response decreases linearly with increasing concentration of analyte. Over a range of methylene blue concentrations from 0 to 0.4 μmol/mL, the sensor response is linear (R = 0.9496). A concentration variation of 0.1 μmol/mL can cause an absorbance change of 0.402 dB. Moreover, the optical responses of the same sensing fiber without decoration and modified with silver nanoparticles have also been compared. It can be observed that the output intensity of the Ag nanoparticle-modified sensor is enhanced and the sensitivity is higher. Meanwhile, the absorbance spectra are found to be more sensitive to concentration changes compared to the spectra of the peak wavelength. PMID:23519353

  20. Evanescent-wave Infrared Optical Fiber Gas Sensor

    NASA Astrophysics Data System (ADS)

    Wang, Yiding; Wang, Di; Zhong, Hong-Jie; Zhang, Zhiguo

    2000-03-01

    We propose the treatment of amblyopia using yellow-green laser diodes.There are amblyopia children in excess of fifty million in the world.Because the causative agent of amblyopia hasn't been well understood,only roughly considered to be concerned with visual sense cell,optic nerve network and function of nerve center,no appropriate treatment is found up to date.The vision of person is determined by the center hollow region of retina,where there are three kinds of cone cell.The corresponding peak wavelength in absorption spectrum locates 447nm(blue light),532nm (green light)and 565nm(yellow light), respectively.When stimulated by white light, excited degree of three kinds of cone cell are identical,or yellow-green light,to which person eye is most sensitive, will significantly takes effects.Therefore the yellow-green laser diode is suitable for treating amblyopia. The weak laser,namely laser power less than mW order of magnitude,shows curative by stimulating bion tissue.When stimulating light power density is less than 0.001W/cm,the compounding speed of nucleic acid DNA is significantly increased.The growth rate of cell,activity of enzyme,content of hemoglobin and the growth of blood vessel,are all increased.However,it's key to control the dose of light.When the dose transcend some value,a inhibition will occur.The little dose of weak laser treatment can be accumulated with a parabolic characteristics,that is the weak laser generate bion response stengthening gradually versus time.Then it will weaken gradually after the peak.When the treatment duration is longer than a certain time,a inhibition also takes place.A suggested theraphy is characterized by little dose and short treatment course. In a conclusion, the yellow-green laser diode should be used for the treatment of amblyopia.The little dose and short treatment couse are to be adopted.

  1. High-sensitivity four-layer polymer fiber-optic evanescent wave sensor.

    PubMed

    Xin, Xin; Zhong, Nianbing; Liao, Qiang; Cen, Yanyan; Wu, Ruohua; Wang, Zhengkun

    2017-05-15

    We present a novel four-layer structure consisting of bottom, second, third, and surface layers in the sensing region, for a D-shaped step-index fiber-optic evanescent wave (FOEW) sensor. To reduce the background noise, the surface of the longitudinal section in the D-shaped region is coated with a light-absorbing film. We check the morphologies of the second and surface layers, examine the refractive indices (RIs) of the third and surface layers, and analyze the composition of the surface layer. We also investigate the effects of the thicknesses and RIs of the third and surface layers and the LA film on the light transmission and sensitivity of the FOEW sensors. The results highlight the very good sensitivity of the proposed FOEW sensor with a four-layer structure, which reached -0.077 (μg/l)(-1) in the detection of the target antibody; the sensitivity of the novel FOEW sensor was 7.60 and 1.52 times better than that of a conventional sensor with a core-cladding structure and an FOEW sensor with a three-layer structure doped with GeO2. The applications of this high-sensitivity FOEW sensor can be extended to biodefense, disease diagnosis, and biomedical and biochemical analysis.

  2. Effects of surface roughness on optical properties and sensitivity of fiber-optic evanescent wave sensors.

    PubMed

    Zhong, Nianbing; Zhu, Xun; Liao, Qiang; Wang, Yongzhong; Chen, Rong; Sun, Yahui

    2013-06-10

    The effects of surface roughness on the light transmission properties and sensitivity of fiber-optic evanescent wave sensors are investigated. A simple method of increasing the sensitivity based on the surface roughness (pit depth δ and diameter Δ) and incident angle U(i) of light rays on the fiber input end is proposed. We discovered that as 2δ/Δ increases, the transmitted light intensity decreases, but the sensitivity initially increases and then decreases. In sensors containing fibers of various roughnesses, the sensitivity to glucose solutions reached -11.7 mW/riu at 2δ/Δ=0.32 and increased further to -15.3 mW/riu with proper adjustment of U(i).

  3. Fiber-optic voltage sensor with cladded fiber and evanescent wave variation detection

    DOEpatents

    Wood, Charles B.

    1992-01-01

    A fiber optic voltage sensor is described which includes a source of light, a reference fiber for receiving a known percentage of the light and an electrostrictive element having terminals across which is applied, a voltage to be measured. The electrostrictive element is responsive to the applied voltage to assume an altered physical state. A measuring fiber also receives a known percentage of light from the light source and is secured about the electrostrictive element. The measuring fiber is provided with a cladding and exhibits an evanescent wave in the cladding. The measuring fiber has a known length which is altered when the electrostrictive element assumes its altered physical state. A differential sensor is provided which senses the intensity of light in both the reference fiber and the measuring fiber and provides an output indicative of the difference between the intensities.

  4. Fiber-optic voltage sensor with cladded fiber and evanescent wave variation detection

    DOEpatents

    Wood, C.B.

    1992-12-15

    A fiber optic voltage sensor is described which includes a source of light, a reference fiber for receiving a known percentage of the light and an electrostrictive element having terminals across which is applied, a voltage to be measured. The electrostrictive element is responsive to the applied voltage to assume an altered physical state. A measuring fiber also receives a known percentage of light from the light source and is secured about the electrostrictive element. The measuring fiber is provided with a cladding and exhibits an evanescent wave in the cladding. The measuring fiber has a known length which is altered when the electrostrictive element assumes its altered physical state. A differential sensor is provided which senses the intensity of light in both the reference fiber and the measuring fiber and provides an output indicative of the difference between the intensities. 3 figs.

  5. Evanescent wave absorption sensor based on tapered multimode fiber coated with monolayer graphene film

    NASA Astrophysics Data System (ADS)

    Qiu, Hengwei; Gao, Saisai; Chen, Peixi; Li, Zhen; Liu, Xiaoyun; Zhang, Chao; Xu, Yuanyuan; Jiang, Shouzhen; Yang, Cheng; Huo, Yanyan; Yue, Weiwei

    2016-05-01

    An evanescent wave absorption (EWA) sensor based on tapered multimode fiber (TMMF) coated with monolayer graphene film for the detection of double-stranded DNA (DS-DNA) is investigated in this work. The TMMF is a silica multimode fiber (nominally at 62.5 μm), which was tapered to symmetric taper with waist diameters of ~30 μm and total length of ~3 mm. Monolayer graphene film was grown on a copper foil via chemical vapor deposition (CVD) technology and transferred onto skinless tapered fiber core via dry transfer technology. All the components of the sensor are coupled together by fusion splicer in order to eliminate the external disturbance. DS-DNA is created by the assembly of two relatively complemented oligonucleotides. The measurements are obtained by using a spectrometer in the optical wavelength range of 400-900 nm. With the increase of DS-DNA concentration, the output light intensity (OPLI) arisen an obvious attenuation. Importantly, the absorbance (A) and the DS-DNA concentrations shown a reasonable linear variation in a wide range of 5-400 μM. Through a series of comparison, the accuracy of TMMF sensor with graphene (G-TMMF) is much better than that without graphene (TMMF), which can be attributed to the molecular enrichment of graphene by π-π stacking.

  6. Evanescent wave absorption based fiber optic pH sensor prepared by dye doped sol-gel immobilization technique

    NASA Astrophysics Data System (ADS)

    Gupta, B. D.; Sharma, D. K.

    1997-02-01

    A fiber optic pH sensor based on evanescent wave absorption is presented. To prepare the probe a small length of the cladding is removed from the middle portion of the fiber. A thin porous film of glass with pH-sensitive dye entrapped in it is deposited on the surface of the unclad portion of the fiber using sol-gel technology. The sensor response and its dynamic range are reported for phenol red, cresol red and bromophenol blue dyes. The sol-gel process has been found to increase the dynamic range of the pH sensor.

  7. Detection of the tumor marker mucine with a diode-laser-based evanescent wave sensor

    NASA Astrophysics Data System (ADS)

    Bock, Daniel; Kaul, Sepp; Loescher, Frank; Ruckstuhl, Thomas; Schulz, V.; Ueberfeld, J.; Seeger, Stefan

    1996-11-01

    Optical sensors based on the utilization of the evanescent field arising at the interface between two media in the case of total internal reflection are an excellent tool for the reduction of time consuming and complex chemical analysis. We developed a fiber-optic based set-up with visible diode lasers as excitation sources. As recognition element an optical fiber covered with a photopolymerized antibody monolayer was used. Beside the commercially available cyanine fluorescent dye Cy 5, newly developed fluorescent dyes in the red spectral region were coupled to antibodies. In order to test the set-up in a clinically relevant system the antibodies BM-2 and BM-7 were chosen. With this antibody system the tumor marker mucine in a sandwich immunoassay was investigated. This protein shows increased concentrations in serum and ascites in the case of breast cancer. The combination of semiconductor devices and ultrathin antibody layers together with an antibody system directed against mucine offers the possibility of an on-line detection of the tumor marker.

  8. Sensitivity enhancement of an in-fiber Michelson interferometer evanescent wave sensor using a silver nanoparticle-polymer composite overlay

    NASA Astrophysics Data System (ADS)

    Sandhu, Sukhpawan S.; Yang, Jian; Xu, C. Q.

    2008-02-01

    Many configurations of fiber optic evanescent wave sensors have recently been explored, with various structural and material modifications applied in attempt to increase their resolution and/or sensitivity. With the aid of long period gratings inscribed within the core of standard single mode fibers, fiber optic evanescent wave sensors with in-fiber interferometric configurations have been realized and have been shown to have excellent resolution due to sharp spectral features. The Michelson interferometer configuration, whereby a single long period grating acts as a beam splitter for the core and cladding modes, is of interest because it operates in reflection mode, which allows for easy signal detection schemes. In this work, it is experimentally demonstrated for the first time that the deposition of a nanoparticle-polymer composite high refractive index overlay film onto the cladding arm surface of such an interferometric sensor greatly increases its sensitivity. Film refractive indices of > 1.7 are achieved and can be further increased to > 2 upon repetition of the nanoparticle synthesis cycle. Sensitivity enhancement factors as large as 16.7 occur in the film index range of 1.9 - 2.1. Experimental data are presented and compared to the theoretical simulation results.

  9. Fabrication of tapered single mode fiber by chemical etching and used as a chemical sensor based on evanescent field absorption

    NASA Astrophysics Data System (ADS)

    Gangopadhyay, Tarun K.; Halder, A.; Das, S.; Paul, M. C.; Pal, M.; Salza, M.; Gagliardi, G.

    2010-12-01

    Single mode tapered fiber (SMTF) has been fabricated with core diameter of 8 μm and reduced cladding diameter up to 11 μm by hydrofluoric acid (HF) etching technique. To obtain the required cladding diameter, the time of etching has been optimized by using different HF concentrations. The mechanism as well as kinetics path of etching reaction on standard optical fiber is discussed. This study is related to surface catalyzed dissociation of HF followed by direct reaction with adsorbate molecules and the surface silicon oxide molecules. The etched tapered fibers are then packaged on quartz substrate to use as sensor element. Finally, the etched fiber is used as an element within chemical sensor based on evanescent field absorption. In this experiment, a 419-ppm cobalt nitrate solution is used for sensing.

  10. A terahertz plastic wire based evanescent field sensor for high sensitivity liquid detection.

    PubMed

    You, Borwen; Liu, Tze-An; Peng, Jin-Long; Pan, Ci-Ling; Lu, Ja-Yu

    2009-11-09

    A highly sensitive detection method based on the evanescent wave of a terahertz subwavelength plastic wire was demonstrated for liquid sensing. Terahertz power spreading outside the wire core makes the waveguide dispersion sensitive to the cladding index variation, resulting in a considerable deviation of waveguide dispersion. Two liquids with transparent appearances, water and alcohol, are easily distinguished based on the waveguide dispersion, which is consistent with theoretical predictions. A melamine alcohol solution with various concentrations is identified successfully, and the detection limit is up to 20ppm, i.e. equivalent to the index variation on the order of 0.01.

  11. Photonic crystal fiber based evanescent-wave sensor for detection of biomolecules in aqueous solutions.

    PubMed

    Jensen, Jesper B; Pedersen, Lars H; Hoiby, Poul E; Nielsen, Lars B; Hansen, T P; Folkenberg, J R; Riishede, J; Noordegraaf, Danny; Nielsen, Kristian; Carlsen, A; Bjarklev, A

    2004-09-01

    We demonstrate highly efficient evanescent-wave detection of fluorophore-labeled biomolecules in aqueous solutions positioned in the air holes of the microstructured part of a photonic crystal fiber. The air-suspended silica structures located between three neighboring air holes in the cladding crystal guide light with a large fraction of the optical field penetrating into the sample even at wavelengths in the visible range. An effective interaction length of several centimeters is obtained when a sample volume of less than 1 microL is used.

  12. Optical fiber evanescent wave adsorption sensors for high-temperature gas sensing in advanced coal-fired power plants

    SciTech Connect

    Buric, M.; Ohodnicky, P.; Duy, J.

    2012-01-01

    Modern advanced energy systems such as coal-fired power plants, gasifiers, or similar infrastructure present some of the most challenging harsh environments for sensors. The power industry would benefit from new, ultra-high temperature devices capable of surviving in hot and corrosive environments for embedded sensing at the highest value locations. For these applications, we are currently exploring optical fiber evanescent wave absorption spectroscopy (EWAS) based sensors consisting of high temperature core materials integrated with novel high temperature gas sensitive cladding materials. Mathematical simulations can be used to assist in sensor development efforts, and we describe a simulation code that assumes a single thick cladding layer with gas sensitive optical constants. Recent work has demonstrated that Au nanoparticle-incorporated metal oxides show a potentially useful response for high temperature optical gas sensing applications through the sensitivity of the localized surface plasmon resonance absorption peak to ambient atmospheric conditions. Hence, the simulation code has been applied to understand how such a response can be exploited in an optical fiber based EWAS sensor configuration. We demonstrate that interrogation can be used to optimize the sensing response in such materials.

  13. Sensitivity enhancement of evanescent waveguide optical sensor for detecting adulterant traces in petroleum products using SiON technology

    NASA Astrophysics Data System (ADS)

    Dutta, Aradhana; Deka, Bidyut; Sahu, Partha Pratim

    2013-11-01

    The development of an evanescent waveguide optical sensor incorporating planar waveguide geometry using silicon oxynitride as the core layer on silica-silicon wafer and its implementation for detection of adulterant traces in petroleum products is presented in this paper. This work focuses on enhancement of sensitivity and analyzed by using Simple Effective Index Method (SEIM), based on sinusoidal modes. The embedded waveguide of length ~ 10,000 μm and core width ~ 50 μm have been developed using SiON technology and applied for checking adulteration so as to ensure the purity of the fuel such that the engine will give the desired performance including low emissions yielding better accuracy and high sensitivity within a very short pulse. The thin cladding layer acts as the analytes (mixture of adulterated fuel) that supports the waveguiding film having a refractive index smaller than that of the core. The main aim of this present work is to encompass a speedy choice to the time-consuming existing methods for detecting adulterated fuels, which generally requires some time to give the consequence. The developed sensor allows spot determination of the percentage concentration of adulterant in pure petrol without involving any chemical analysis. The waveguide based sensor is polarization independent and the sensitivity of the waveguide sensor is ~10 times more than that of the existing planar waveguide sensors and also 5 times more than that of asymmetric waveguide structure. Advantages include high sensitivity, simple fabrication and easy interrogation without involving the use of solvents or toxic chemicals.

  14. Moisture sensor based on evanescent wave light scattering by porous sol-gel silica coating

    DOEpatents

    Tao, Shiquan; Singh, Jagdish P.; Winstead, Christopher B.

    2006-05-02

    An optical fiber moisture sensor that can be used to sense moisture present in gas phase in a wide range of concentrations is provided, as well techniques for making the same. The present invention includes a method that utilizes the light scattering phenomenon which occurs in a porous sol-gel silica by coating an optical fiber core with such silica. Thus, a porous sol-gel silica polymer coated on an optical fiber core forms the transducer of an optical fiber moisture sensor according to an embodiment. The resulting optical fiber sensor of the present invention can be used in various applications, including to sense moisture content in indoor/outdoor air, soil, concrete, and low/high temperature gas streams.

  15. Dye distance mapping using waveguide evanescent field fluorescence microscopy and its application to cell biology.

    PubMed

    Fleissner, Frederik; Morawitz, Michael; Dixon, S Jeffrey; Langbein, Uwe; Mittler, Silvia

    2015-10-01

    Previous studies have measured the distance between cells and the substratum at sites of adhesion via the emission of a fluorescent dye and waveguide methods. Here, we demonstrate a novel approach to measure the position of fluorescent dyes above a waveguide surface in the 10-200 nm distance range throughout an entire area, yielding a 2D dye distance map or a 3D contour plot. The dye is located in a multilayered Langmuir Blodgett (LB) film or in the plasma membrane of a cell. Waveguide evanescent field fluorescence (WEFF) images obtained using two different waveguide modes are employed allowing, with a simple mathematical approach, the calculation of dye distance maps. Ultra-thin steps made using LB technology, adhesion distances and the bending of the plasma membrane between focal adhesions of osteoblastic cells are shown as examples. The errors are discussed. False color representation of a dye distance map with four osteoblasts. The inset represents an overexposed WEFF image of the same field of view.

  16. Oxygen detection using evanescent fields

    DOEpatents

    Duan, Yixiang; Cao, Weenqing

    2007-08-28

    An apparatus and method for the detection of oxygen using optical fiber based evanescent light absorption. Methylene blue was immobilized using a sol-gel process on a portion of the exterior surface of an optical fiber for which the cladding has been removed, thereby forming an optical oxygen sensor. When light is directed through the optical fiber, transmitted light intensity varies as a result of changes in the absorption of evanescent light by the methylene blue in response to the oxygen concentration to which the sensor is exposed. The sensor was found to have a linear response to oxygen concentration on a semi-logarithmic scale within the oxygen concentration range between 0.6% and 20.9%, a response time and a recovery time of about 3 s, ant to exhibit good reversibility and repeatability. An increase in temperature from 21.degree. C. to 35.degree. C. does not affect the net absorption of the sensor.

  17. A high-sensitivity fiber-optic evanescent wave sensor with a three-layer structure composed of Canada balsam doped with GeO2.

    PubMed

    Zhong, Nianbing; Zhao, Mingfu; Zhong, Lianchao; Liao, Qiang; Zhu, Xun; Luo, Binbin; Li, Yishan

    2016-11-15

    In this paper, we present a high-sensitivity polymer fiber-optic evanescent wave (FOEW) sensor with a three-layer structure that includes bottom, inter-, and surface layers in the sensing region. The bottom layer and inter-layer are POFs composed of standard cladding and the core of the plastic optical fiber, and the surface layer is made of dilute Canada balsam in xylene doped with GeO2. We examine the morphology of the doped GeO2, the refractive index and composition of the surface layer and the surface luminous properties of the sensing region. We investigate the effects of the content and morphology of the GeO2 particles on the sensitivity of the FOEW sensors by using glucose solutions. In addition, we examine the response of sensors incubated with staphylococcal protein A plus mouse IgG isotype to goat anti-mouse IgG solutions. Results indicate very good sensitivity of the three-layer FOEW sensor, which showed a 3.91-fold improvement in the detection of the target antibody relative to a conventional sensor with a core-cladding structure, and the novel sensor showed a lower limit of detection of 0.2ng/l and a response time around 320s. The application of this high-sensitivity FOEW sensor can be extended to biodefense, disease diagnosis, biomedical and biochemical analysis.

  18. Study of Evanescence Wave Absorption in Lindane

    NASA Astrophysics Data System (ADS)

    Marzuki, A.; Prasetyo, E.; Gitrin, M. P.; Suryanti, V.

    2017-02-01

    Evanescent wave field has been studied for the purpose of tailoring fiber sensor capable of detecting lindane concentration in a solution. The mounted fiber was optically polished such that part of the fiber clad is stripped off. To study the evanescent wave field absorption in lindane solution, the unclad fiber was immersed in the solution. Light coming out of the fiber was studied at different wavelength each for different lindane concentration. It was shown that evanescent wave field absorption is stronger at wavelength corresponding to lindane absorption band as has been shown from absorption studies lindane in UV-VIS-NIR spectrophotometer.

  19. Fiber optic NIR evanescent wave absorption sensor systems for in-situ monitoring of hydrocarbon compounds in waste and ground water

    NASA Astrophysics Data System (ADS)

    Buerck, Jochen; Denter, P.; Mensch, M.; Kraemer, K.; Scholz, Michael

    1999-02-01

    In situ measurements with the prototype of a portable fiber- optic sensor system for the monitoring of nonpolar hydrocarbons (HC) in ground water or industrial waste water are presented. This sensor system can be used for quantitative in situ analysis of pollutants such as aromatic solvents, fuels, mineral oils or chlorinated HCs in a broad concentration range from around 200 (mu) g(DOT) L-1 up to a few 100 mg(DOT) L-1. The sensing principle is based on solid phase extraction of analyte molecules into a hydrophobic silicone cladding of a quartz glass optical fiber and the direct absorptiometric measurement of the extracted species in the polymer through the evanescent wave. The sensor can be connected via all-silica fibers with a length of up to 100 m to a filter photometer developed at the IFIA, thus allowing even remote analysis in monitoring wells. This instrument provides a sum concentration signal of the extracted organic compounds by measuring the integral absorption at the C-H overtone bands in the near-infrared spectral range. In situ measurements with the sensor system were performed in a ground water circulation well at the VEGAS research facility (Universitat Stuttgart). Here, the sensor proved to trace the HC sum concentration of xylene isomers in process water pumped from the well to a stripper column. In further experiments the sensor was combined with an oil sampling device and was tested with simulated waste waters of a commercial vehicle plant contaminated with different types of mineral oil. In this case the sensor system was able to detect the presence of mineral oil films floating on water or oil-in-water emulsions with concentrations greater than 20 ppm (v/v) within a few minutes.

  20. Gondola-shaped tetra-rhenium metallacycles modified evanescent wave infrared chemical sensors for selective determination of volatile organic compounds.

    PubMed

    Huang, Genin Gary; Lee, Chung-Jay; Tsai, Bo-Chan; Yang, Jyisy; Sathiyendiran, Malaichamy; Lu, Kuang-Lieh

    2011-07-15

    Water-stable and cavity-contained rhenium metallacycles were synthesized, and their ability to selectively interact with volatile organic compounds (VOCs) systematically studied using attenuated total reflection infrared (ATR-IR) spectroscopy. Integrating the unique properties of rhenium metallacycles into optical sensing technologies significantly improves selectivity in detecting aromatic compounds. To explore the interaction of rhenium metallacycles with VOCs, the surface of ATR sensing elements was modified with the synthesized rhenium metallacycles and used to detect VOCs. The results indicate that rhenium metallacycles have crown ether-like recognition sites, which can selectively interact with aromatic compounds, especially those bearing polar functional groups. The IR absorption bands of rhenium metallacycles shift significantly upon adsorption of aromatic VOCs, revealing a strong interaction between the tetra-rhenium metallacycles and guest aromatic compounds. Optimizing the thickness of the metallacycles coated on the surface of the sensing element led to rapid response in detection. The dynamic range of response was generally up to 30 mg/L with detection limits ca. 30 μg/L. Further studies of the effect of interferences indicate that recovery can be higher than 95% for most of the compounds tested. The results on the flow-cell device indicated that the performances were similar to a static detection system but the detection of VOCs can be largely simplified.

  1. Sapphire fiber evanescent wave absorption in turbid media.

    PubMed

    Zhang, Jian; Xiong, Feibing; Djeu, Nicholas

    2009-08-01

    The influence of particulates on sapphire fiber evanescent wave absorption by water has been studied. Suspensions containing micro-sized graphite flakes and glassy carbon powder were used. Conventional free-space transmittance measurements of these samples showed strong absorption and scattering, which severely screened the absorption by water. However, the absorption on the water band determined from the evanescent wave interaction was unaffected by the presence of the graphite flakes. These results indicate that fiber-optic evanescent wave chemical sensors may be suitable for process control applications involving turbid reactor streams.

  2. Applications of Microbial Cell Sensors

    NASA Astrophysics Data System (ADS)

    Shimomura-Shimizu, Mifumi; Karube, Isao

    Since the first microbial cell sensor was studied by Karube et al. in 1977, many types of microbial cell sensors have been developed as analytical tools. The microbial cell sensor utilizes microbes as a sensing element and a transducer. The characteristics of microbial cell sensors as sensing devices are a complete contrast to those of enzyme sensors or immunosensors, which are highly specific for the substrates of interest, although the specificity of the microbial cell sensor has been improved by genetic modification of the microbe used as the sensing element. Microbial cell sensors have the advantages of tolerance to measuring conditions, a long lifetime, and good cost performance, and have the disadvantage of a long response time. In this review, applications of microbial cell sensors are summarized.

  3. Axial super-resolution evanescent wave tomography

    NASA Astrophysics Data System (ADS)

    Pendharker, Sarang; Shende, Swapnali; Newman, Ward; Ogg, Stephen; Nazemifard, Neda; Jacob, Zubin

    2016-12-01

    Optical tomographic reconstruction of a 3D nanoscale specimen is hindered by the axial diffraction limit, which is 2-3 times worse than the focal plane resolution. We propose and experimentally demonstrate an axial super-resolution evanescent wave tomography (AxSET) method that enables the use of regular evanescent wave microscopes like Total Internal Reflection Fluorescence Microscope (TIRF) beyond surface imaging, and achieve tomographic reconstruction with axial super-resolution. Our proposed method based on Fourier reconstruction achieves axial super-resolution by extracting information from multiple sets of three-dimensional fluorescence images when the sample is illuminated by an evanescent wave. We propose a procedure to extract super-resolution features from the incremental penetration of an evanescent wave and support our theory by 1D (along the optical axis) and 3D simulations. We validate our claims by experimentally demonstrating tomographic reconstruction of microtubules in HeLa cells with an axial resolution of $\\sim$130 nm. Our method does not require any additional optical components or sample preparation. The proposed method can be combined with focal plane super-resolution techniques like STORM and can also be adapted for THz and microwave near-field tomography.

  4. Axial super-resolution evanescent wave tomography.

    PubMed

    Pendharker, Sarang; Shende, Swapnali; Newman, Ward; Ogg, Stephen; Nazemifard, Neda; Jacob, Zubin

    2016-12-01

    Optical tomographic reconstruction of a three-dimensional (3D) nanoscale specimen is hindered by the axial diffraction limit, which is 2-3 times worse than the focal plane resolution. We propose and experimentally demonstrate an axial super-resolution evanescent wave tomography method that enables the use of regular evanescent wave microscopes like the total internal reflection fluorescence microscope beyond surface imaging and achieve a tomographic reconstruction with axial super-resolution. Our proposed method based on Fourier reconstruction achieves axial super-resolution by extracting information from multiple sets of 3D fluorescence images when the sample is illuminated by an evanescent wave. We propose a procedure to extract super-resolution features from the incremental penetration of an evanescent wave and support our theory by one-dimensional (along the optical axis) and 3D simulations. We validate our claims by experimentally demonstrating tomographic reconstruction of microtubules in HeLa cells with an axial resolution of ∼130  nm. Our method does not require any additional optical components or sample preparation. The proposed method can be combined with focal plane super-resolution techniques like stochastic optical reconstruction microscopy and can also be adapted for THz and microwave near-field tomography.

  5. Pathogen detection using evanescent-wave fiber optic biosensor

    NASA Astrophysics Data System (ADS)

    Ferreira, Aldo P.; Werneck, Marcelo M.; Ribeiro, R. M.; Lins, U. G.

    1999-07-01

    This paper describes a real time optical biosensor that utilizes the evanescent field technique for monitoring microorganisms in hospital environment. The biosensor monitors interactions between the analytic (bacteria) and the evanescent field of an optical fiber passing through the culture media where the bacteria grows. The objective is to monitor atmospheres in hospital areas for the Staphylococcus aureus and Streptococcus pneumonia. The results lead us the conclusion that this kind of sensor presents quick response, good performance, easy of construction and low cost. We expect that the sensor will be of great help in controlling the hospital environment.

  6. Fuel cell CO sensor

    DOEpatents

    Grot, Stephen Andreas; Meltser, Mark Alexander; Gutowski, Stanley; Neutzler, Jay Kevin; Borup, Rodney Lynn; Weisbrod, Kirk

    1999-12-14

    The CO concentration in the H.sub.2 feed stream to a PEM fuel cell stack is monitored by measuring current and/or voltage behavior patterns from a PEM-probe communicating with the reformate feed stream. Pattern recognition software may be used to compare the current and voltage patterns from the PEM-probe to current and voltage telltale outputs determined from a reference cell similar to the PEM-probe and operated under controlled conditions over a wide range of CO concentrations in the H.sub.2 fuel stream. A CO sensor includes the PEM-probe, an electrical discharge circuit for discharging the PEM-probe to monitor the CO concentration, and an electrical purging circuit to intermittently raise the anode potential of the PEM-probe's anode to at least about 0.8 V (RHE) to electrochemically oxidize any CO adsorbed on the probe's anode catalyst.

  7. Wigner functions for evanescent waves.

    PubMed

    Petruccelli, Jonathan C; Tian, Lei; Oh, Se Baek; Barbastathis, George

    2012-09-01

    We propose phase space distributions, based on an extension of the Wigner distribution function, to describe fields of any state of coherence that contain evanescent components emitted into a half-space. The evanescent components of the field are described in an optical phase space of spatial position and complex-valued angle. Behavior of these distributions upon propagation is also considered, where the rapid decay of the evanescent components is associated with the exponential decay of the associated phase space distributions. To demonstrate the structure and behavior of these distributions, we consider the fields generated from total internal reflection of a Gaussian Schell-model beam at a planar interface.

  8. Evanescent Wave Atomic Mirror

    NASA Astrophysics Data System (ADS)

    Ghezali, S.; Taleb, A.

    2008-09-01

    A research project at the "Laboratoire d'électronique quantique" consists in a theoretical study of the reflection and diffraction phenomena via an atomic mirror. This poster presents the principle of an atomic mirror. Many groups in the world have constructed this type of atom optics experiments such as in Paris-Orsay-Villetaneuse (France), Stanford-Gaithersburg (USA), Munich-Heidelberg (Germany), etc. A laser beam goes into a prism with an incidence bigger than the critical incidence. It undergoes a total reflection on the plane face of the prism and then exits. The transmitted resulting wave out of the prism is evanescent and repulsive as the frequency detuning of the laser beam compared to the atomic transition δ = ωL-ω0 is positive. The cold atomic sample interacts with this evanescent wave and undergoes one or more elastic bounces by passing into backward points in its trajectory because the atoms' kinetic energy (of the order of the μeV) is less than the maximum of the dipolar potential barrier ℏΩ2/Δ where Ω is the Rabi frequency [1]. In fact, the atoms are cooled and captured in a magneto-optical trap placed at a distance of the order of the cm above the prism surface. The dipolar potential with which interact the slow atoms is obtained for a two level atom in a case of a dipolar electric transition (D2 Rubidium transition at a wavelength of 780nm delivered by a Titane-Saphir laser between a fundamental state Jf = l/2 and an excited state Je = 3/2). This potential is corrected by an attractive Van der Waals term which varies as 1/z3 in the Lennard-Jones approximation (typical atomic distance of the order of λ0/2π where λ0 is the laser wavelength) and in 1/z4 if the distance between the atom and its image in the dielectric is big in front of λ0/2π. This last case is obtained in a quantum electrodynamic calculation by taking into account an orthornormal base [2]. We'll examine the role of spontaneous emission for which the rate is inversely

  9. Evaluation of Anti-A/Udorn/307/1972 Antibody Specificity to Influenza A/H3N2 Viruses Using an Evanescent-Field Coupled Waveguide-Mode Sensor

    PubMed Central

    Gopinath, Subash C. B.; Awazu, Koichi; Fujimaki, Makoto; Shimizu, Kazufumi

    2013-01-01

    Discrimination of closely related strains is a key issue, particularly for infectious diseases whose incidence fluctuates according to variations in the season and evolutionary changes. Among infectious diseases, influenza viral infections are a worldwide cause of pandemic disease and mortality. With the emergence of different influenza strains, it is vital to develop a method using antibodies that can differentiate between viral types and subtypes. Ideally, such a system would also be user friendly. In this study, a polyclonal antibody generated against A/Udorn/307/1972 (H3N2) was used as a probe to distinguish between influenza H3N2 viruses based on the interaction between the antibody and hemagglutinin, demonstrating its applicability for viral discrimination. Clear discrimination was demonstrated using an evanescent-field-coupled waveguide-mode sensor, which has appealing characteristics over other methods in the viewpoint of improving the sensitivity, measurement time, portability and usability. Further supporting evidence was obtained using enzyme-linked immunosorbent assays, hemagglutination-inhibition assays, and infectivity neutralization assays. The results obtained indicate that the polyclonal antibody used here is a potential probe for distinguishing influenza viruses and, with the aid of a handheld sensor it could be used for influenza surveillance. PMID:24339924

  10. Optical immunoassay systems based upon evanescent wave interactions

    NASA Astrophysics Data System (ADS)

    Christensen, Douglas A.; Herron, James N.

    1996-04-01

    Immunoassays based upon evanescent wave interactions are finding increased biosensing application. In these devices, the evanescent tail associated with total internal reflection of an incident beam at the substrate/solution interface provides sensitivity for surface-bound protein over bulk molecules, allowing homogeneous assays and real-time measurement of binding dynamics. Among such systems are surface plasmon resonance sensors and a resonant mirror device. Several research groups are also developing fluorescent fiberoptic or planar waveguide sensors for biomedical applications. We describe a second-generation planar waveguide fluoroimmunoassay system being developed in our laboratory which uses a molded polystyrene sensor. The 633-nm beam from a laser diode is focused into the 500 micrometer- thick planar waveguide by an integral lens. Antibodies to the desired analyte (hCG) are immobilized on the waveguide surface and fluorescence from bound analyte/tracer antibodies in a sandwich format is imaged onto the detector. The geometry of the waveguide allows several zones to be detected, providing the capability for on-sensor calibration. This sensor has shown picomolar sensitivity for the detection of hCG.

  11. Conversion of evanescent Lamb waves into propagating waves via a narrow aperture edge.

    PubMed

    Yan, Xiang; Yuan, Fuh-Gwo

    2015-06-01

    This paper presents a quantitative study of conversion of evanescent Lamb waves into propagating in isotropic plates. The conversion is substantiated by prescribing time-harmonic Lamb displacements/tractions through a narrow aperture at an edge of a semi-infinite plate. Complex-valued dispersion and group velocity curves are employed to characterize the conversion process. The amplitude coefficient of the propagating Lamb modes converted from evanescent is quantified based on the complex reciprocity theorem via a finite element analysis. The power flow generated into the plate can be separated into radiative and reactive parts made on the basis of propagating and evanescent Lamb waves, where propagating Lamb waves are theoretically proved to radiate pure real power flow, and evanescent Lamb waves carry reactive pure imaginary power flow. The propagating power conversion efficiency is then defined to quantitatively describe the conversion. The conversion efficiency is strongly frequency dependent and can be significant. With the converted propagating waves from evanescent, sensors at far-field can recapture some localized damage information that is generally possessed in evanescent waves and may have potential application in structural health monitoring.

  12. Counting cells with a low-cost integrated microfluidics-waveguide sensor.

    PubMed

    Garcia, Daniel; Ghansah, Isaac; Leblanc, John; Butte, Manish J

    2012-03-01

    The capability to count cells from biofluids at low cost has important diagnostic implications in resource-poor settings. Many approaches have been developed to address this important need, and while most envision a low per-test cost, the detector instrument can be quite expensive. In this report, we present a novel device that enables low-cost and rapid counting of cells from a drop of blood. We demonstrate a shallow, buried, planar waveguide fabricated by ion exchange in glass that underlies a microfluidic structure for capturing cells. Laser light transmitted through the waveguide was attenuated by the number of metal nanoparticles tagged to the cells because of the interaction of the metal particles with the evanescent field of the waveguide. Calibration of the sensor using bead-tagged lymphocytes captured from human blood showed that the sensor could semi-quantitatively count as few as 100 cells/µL of blood. This technology enables the enumeration of specifically captured cells, allowing for a point-of-care, hand-held device for fast and affordable cell counting in screening, remote, or resource-poor settings.

  13. Polymer slab waveguides for the optical detection of nanoparticles in evanescent field based biosensors

    NASA Astrophysics Data System (ADS)

    Teigell Beneitez, Nuria; Missinne, Jeroen; Schleipen, Jean; Orsel, Joke; Prins, Menno W. J.; Van Steenberge, Geert

    2014-02-01

    We present a polymer optical waveguide integration technology for the detection of nanoparticles in an evanescent field based biosensor. In the proposed biosensor concept, super-paramagnetic nanoparticles are used as optical contrast labels. The nanoparticles capture target molecules from a sample fluid and bind to the sensor surface with biological specificity. The surface-bound nanoparticles are then detected using frustration of an evanescent field. In the current paper we elaborate on the polymer waveguides which are used to generate a well-defined optical field for nanoparticle detection.

  14. Nanoparticle PEBBLE sensors in live cells.

    PubMed

    Lee, Yong-Eun Koo; Kopelman, Raoul

    2012-01-01

    Live cell studies are of fundamental importance to the life sciences and their medical applications. Nanoparticle (NP)-based sensor platforms have many advantages as sensors for intracellular measurements, due to their flexible engineerability, noninvasive nature (due to their nano-size and nontoxic matrix), and, for some of the NPs, intrinsic optical properties. NP-based fluorescent sensors for intracellular measurements, so called PEBBLE sensors, have been developed for many important intracellular analytes and functions, including ions, small molecules, reactive oxygen species, physical properties, and enzyme activities, which are involved in many chemical, biochemical, and physical processes taking place inside the cell. PEBBLE sensors can be used with a standard microscope for simultaneous optical imaging of cellular structures and sensing of composition and function, just like investigations performed with molecular probes. However, PEBBLE sensors of any design and matrix can be delivered into cells by several standard methods, unlike dye molecules that need to be cell permeable. Furthermore, new sensing possibilities are enabled by PEBBLE nanosensors, which are not possible with molecular probes. This review summarizes a variety of designs of the PEBBLE sensors, their characteristics, and their applications to cells.

  15. Model-based optimal design of polymer-coated chemical sensors.

    PubMed

    Phillips, Cynthia; Jakusch, Michael; Steiner, Hannes; Mizaikoff, Boris; Fedorov, Andrei G

    2003-03-01

    A model-based methodology for optimal design of polymer-coated chemical sensors is developed and is illustrated for the example of infrared evanescent field chemical sensors. The methodology is based on rigorous and computationally efficient modeling of combined fluid mechanics and mass transfer, including transport of multiple analytes. A simple algebraic equation for the optimal size of the sensor flow cell is developed to guide sensor design and validated by extensive CFD simulations. Based upon these calculations, optimized geometries of the sensor flow cell are proposed to further improve the response time of chemical sensors.

  16. Extraordinary momentum and spin in evanescent waves.

    PubMed

    Bliokh, Konstantin Y; Bekshaev, Aleksandr Y; Nori, Franco

    2014-03-06

    Momentum and spin represent fundamental dynamic properties of quantum particles and fields. In particular, propagating optical waves (photons) carry momentum and longitudinal spin determined by the wave vector and circular polarization, respectively. Here we show that exactly the opposite can be the case for evanescent optical waves. A single evanescent wave possesses a spin component, which is independent of the polarization and is orthogonal to the wave vector. Furthermore, such a wave carries a momentum component, which is determined by the circular polarization and is also orthogonal to the wave vector. We show that these extraordinary properties reveal a fundamental Belinfante's spin momentum, known in field theory and unobservable in propagating fields. We demonstrate that the transverse momentum and spin push and twist a probe Mie particle in an evanescent field. This allows the observation of 'impossible' properties of light and of a fundamental field-theory quantity, which was previously considered as 'virtual'.

  17. Fast wave evanescence in filamentary boundary plasmas

    SciTech Connect

    Myra, J. R.

    2014-02-15

    Radio frequency waves for heating and current drive of plasmas in tokamaks and other magnetic confinement devices must first traverse the scrape-off-layer (SOL) before they can be put to their intended use. The SOL plasma is strongly turbulent and intermittent in space and time. These turbulent properties of the SOL, which are not routinely taken into account in wave propagation codes, can have an important effect on the coupling of waves through an evanescent SOL or edge plasma region. The effective scale length for fast wave (FW) evanescence in the presence of short-scale field-aligned filamentary plasma turbulence is addressed in this paper. It is shown that although the FW wavelength or evanescent scale length is long compared with the dimensions of the turbulence, the FW does not simply average over the turbulent density; rather, the average is over the exponentiation rate. Implications for practical situations are discussed.

  18. Scanning evanescent electro-magnetic microscope

    DOEpatents

    Xiang, Xiao-Dong; Gao, Chen

    2001-01-01

    A novel scanning microscope is described that uses near-field evanescent electromagnetic waves to probe sample properties. The novel microscope is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The inventive scanning evanescent wave electromagnetic microscope (SEMM) can map dielectric constant, tangent loss, conductivity, complex electrical impedance, and other electrical parameters of materials. The quantitative map corresponds to the imaged detail. The novel microscope can be used to measure electrical properties of both dielectric and electrically conducting materials.

  19. Scanning evanescent electro-magnetic microscope

    DOEpatents

    Xiang, Xiao-Dong; Gao, Chen; Schultz, Peter G.; Wei, Tao

    2003-01-01

    A novel scanning microscope is described that uses near-field evanescent electromagnetic waves to probe sample properties. The novel microscope is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The inventive scanning evanescent wave electromagnetic microscope (SEMM) can map dielectric constant, tangent loss, conductivity, complex electrical impedance, and other electrical parameters of materials. The quantitative map corresponds to the imaged detail. The novel microscope can be used to measure electrical properties of both dielectric and electrically conducting materials.

  20. Improved fuel-cell-type hydrogen sensor

    NASA Technical Reports Server (NTRS)

    Rudek, F. P.; Rutkowski, M. D.

    1968-01-01

    Modified hydrogen sensor replaces oxygen cathode with a cathode consisting of a sealed paste of gold hydroxide and a pure gold current collector. The net reaction which occurs during cell operation is the reduction of the gold hydroxide to gold and water, with a half-cell potential of 1.4 volts.

  1. A magnetic cell-based sensor.

    PubMed

    Wang, Hua; Mahdavi, Alborz; Tirrell, David A; Hajimiri, Ali

    2012-11-07

    Cell-based sensing represents a new paradigm for performing direct and accurate detection of cell- or tissue-specific responses by incorporating living cells or tissues as an integral part of a sensor. Here we report a new magnetic cell-based sensing platform by combining magnetic sensors implemented in the complementary metal-oxide-semiconductor (CMOS) integrated microelectronics process with cardiac progenitor cells that are differentiated directly on-chip. We show that the pulsatile movements of on-chip cardiac progenitor cells can be monitored in a real-time manner. Our work provides a new low-cost approach to enable high-throughput screening systems as used in drug development and hand-held devices for point-of-care (PoC) biomedical diagnostic applications.

  2. Evanescent optical fluorescence excitation: the role of photonic mode density

    NASA Astrophysics Data System (ADS)

    Menges, Bernhard; Sato, Akihiro; Knoll, Wolfgang

    2007-04-01

    In this paper we will discuss a few basic concepts concerning the use of evanescent optical fields for the excitation of fluorescent chromophores placed near the interface. The observation of enhanced fluorescence from chromophores excited by surface plasmon and waveguide modes will be presented and discussed. We attribute the enhancement to the near-field interaction between the chromophores and the increased photonic mode density by surface plasmon and waveguide modes. We determined limits of detection (LOD) of DNA hybridisation using the same sensor architecture by surface plasmon fluorescence spectroscopy (SPFS) and optical waveguide fluorescence spectroscopy (OWFS). Both SPFS and OWFS techniques have the same detection principle using an enhanced electromagnetic field to excite fluorophores and make it possible to monitor DNA hybridisation in real-time with high sensitivity. The relative photonic mode density of each mode was calculated under the resonance condition, and these values are reflected in the LOD values.

  3. Evanescent field excitation of Cy5-conjugated lipid bilayers using optical microcavities

    NASA Astrophysics Data System (ADS)

    Freeman, Lindsay M.; Dayani, Yasaman; Li, Su; Choi, Hong-Seok; Malmstadt, Noah; Armani, Andrea M.

    2011-09-01

    Whispering gallery mode optical microresonators are devices used for performing ultra-sensitive optical detection. Although the majority of the sensor research has been focused on label-free detection strategies for diagnostics, a whispering gallery mode device is ideally suited to perform fluorescent label-based biodetection as well. However, previous research using optical microcavities to excite fluorescent molecules has focused on cavity quantum electrodynamics applications and fundamental studies of the interactions of large fluorescent nanoparticles with the resonant cavity. In the present work, a method for forming self-assembled lipid bilayers, a mimic for cell membranes, on a spherical microresonator is developed. Solid-supported lipid bilayers, which are approximately 5nm thick, have been shown to accurately model cell membranes, and researchers use lipid bilayers in combination with fluorescent microscopy when developing theoretical models for the transport of molecules across the cell membrane. The bilayernature is verified using both fluorescent resonance energy transfer and fluorescence recovery after photobleaching. The evanescent tail of the microresonator is used to excite a Cy5-conjugated lipid located within the bilayer while the underlying optical device behavior is characterized at 633nm and 980nm. The emission wavelength of the Cy5 dye and the optical performance (Q factor) of the microcavity agree with theoretical predictions.

  4. Evanescent cultivation of photosynthetic bacteria on thin waveguides

    NASA Astrophysics Data System (ADS)

    Pierobon, S. C.; Ooms, M. D.; Sinton, D.

    2014-04-01

    Waveguides with thicknesses similar to biofilms (10-100 µm) provide an opportunity to improve the bioenergy density of biofilm photobioreactors, avoiding the fundamental light- and mass-transport productivity limitations of planktonic photobioreactors. This report investigates the biofilm growth of a mutant of Synechococcus elongatus (PCC 7942) in evanescent light fields that can be scaled over large planar areas. In this study, areas of 7.2 cm2 are illuminated via frustrated total internal reflections on planar waveguides. The resulting photosynthetic biofilm growth showed resilience to surface intensities exceeding photosynthetic limits and a more uniform cell density distribution (1.0 ± 0.3 × 109 mL-1) than predicted from surface light distribution profiles. These results indicate potential for larger area biofilms using the uniform lighting conditions identified. The combination of evanescent illumination with biofilms indicates a modular reactor cell density on the order of 108 mL-1, representing a two orders of magnitude improvement over current facility architectures, with significant potential for further improvement through denser biofilms.

  5. Cell Metabolism Monitoring with MEMS Sensor

    NASA Astrophysics Data System (ADS)

    Nakabeppu, Osamu; Sakayori, Junichi

    Cells and living tissue slightly but always generate metabolic heat as long as they are alive. Thus, biological activity can be measured through the observation of metabolic heat, which has been developed as “bio-calorimetry”. On the other hand, further improvements in thermal sensing ability can be expected with use of the MEMS (Micro Electro Mechanical System) technology. The purpose of this study is to develop the monitoring technique of the metabolic heat of cells in as small number as possible with the MEMS technology. If the monitoring technique of metabolism of a few cells or even a single cell is made available, it plays very important rolls in bio- and medical- engineering, pharmaceutical sciences, and so on. In this study, a bio-calorimeter with a MEMS thermopile sensor was made, and its performance and metabolism monitoring of Yeast were tested. The thermopile sensor consisted of 350 thin film thermocouples of Cr and Ni strips of 20 μm width on a 150 μm thick glass plate. The thermopile sensor composed a calorimetric cell as a bottom plate with thick aluminum frame. The calorimetric cell was placed in a triple thermostatic chamber which employs a proportional control with a Peltier device and PID control with heater. The calorimeter showed a sensitivity of 0.62 V/W under the condition of including culture solution, time constant of the calorimetric cell of 90 sec, and a noise equivalent power of 60 nW, which corresponds to metabolic heat of 3 × 103 cells of Yeast. In the growth experiments of Yeast, growth thermograms for 105˜107 cells can be measured with reasonable generation times. It was demonstrated that the detectable number of Yeast cells of the MEMS calorimeter is much smaller than that for the traditional bio-calorimeter.

  6. Microbial Fuel Cells and Sensors

    DTIC Science & Technology

    2007-11-02

    funding foreign research over Quality U.S. research needs to be investigated by government officials. PATENT INFORMATION: Improved fuel cell designs and...Zeikus. Analysis of microbial electrochemical activity in marine sediment. (In preparation) REPOT D CUM NTA ON AGEForm Approved REPOT D CUM NTATON

  7. Wireless sensors powered by microbial fuel cells.

    PubMed

    Shantaram, Avinash; Beyenal, Haluk; Raajan, Raaja; Veluchamy, Angathevar; Lewandowski, Zbigniew

    2005-07-01

    Monitoring parameters characterizing water quality, such as temperature, pH, and concentrations of heavy metals in natural waters, is often followed by transmitting the data to remote receivers using telemetry systems. Such systems are commonly powered by batteries, which can be inconvenient at times because batteries have a limited lifetime and must be recharged or replaced periodically to ensure that sufficient energy is available to power the electronics. To avoid these inconveniences, a microbial fuel cell was designed to power electrochemical sensors and small telemetry systems to transmit the data acquired by the sensors to remote receivers. The microbial fuel cell was combined with low-power, high-efficiency electronic circuitry providing a stable power source for wireless data transmission. To generate enough power for the telemetry system, energy produced by the microbial fuel cell was stored in a capacitor and used in short bursts when needed. Since commercial electronic circuits require a minimum 3.3 V input and our cell was able to deliver a maximum of 2.1 V, a DC-DC converter was used to boost the potential. The DC-DC converter powered a transmitter, which gathered the data from the sensor and transmitted it wirelessly to a remote receiver. To demonstrate the utility of the system, temporal variations in temperature were measured, and the data were wirelessly transmitted to a remote receiver.

  8. Evanescent field of vectorial highly non-paraxial beams.

    PubMed

    Martínez-Herrero, R; Mejías, P M; Carnicer, A

    2008-03-03

    In terms of the Fourier spectrum, a simple but general analytical expression is given for the evanescent field associated to a certain kind of non-paraxial exact solutions of the Maxwell equations. This expression enables one to compare the relative weight of the evanescent wave with regard to the propagating field. In addition, in those cases in which the evanescent term is significant, the magnitude of the field components across the transverse profile (including the evanescent features) can be determined. These results are applied to some illustrative examples.

  9. Mammalian Cell-Based Sensor System

    NASA Astrophysics Data System (ADS)

    Banerjee, Pratik; Franz, Briana; Bhunia, Arun K.

    Use of living cells or cellular components in biosensors is receiving increased attention and opens a whole new area of functional diagnostics. The term "mammalian cell-based biosensor" is designated to biosensors utilizing mammalian cells as the biorecognition element. Cell-based assays, such as high-throughput screening (HTS) or cytotoxicity testing, have already emerged as dependable and promising approaches to measure the functionality or toxicity of a compound (in case of HTS); or to probe the presence of pathogenic or toxigenic entities in clinical, environmental, or food samples. External stimuli or changes in cellular microenvironment sometimes perturb the "normal" physiological activities of mammalian cells, thus allowing CBBs to screen, monitor, and measure the analyte-induced changes. The advantage of CBBs is that they can report the presence or absence of active components, such as live pathogens or active toxins. In some cases, mammalian cells or plasma membranes are used as electrical capacitors and cell-cell and cell-substrate contact is measured via conductivity or electrical impedance. In addition, cytopathogenicity or cytotoxicity induced by pathogens or toxins resulting in apoptosis or necrosis could be measured via optical devices using fluorescence or luminescence. This chapter focuses mainly on the type and applications of different mammalian cell-based sensor systems.

  10. A hybrid silicon evanescent quantum dot laser

    NASA Astrophysics Data System (ADS)

    Jang, Bongyong; Tanabe, Katsuaki; Kako, Satoshi; Iwamoto, Satoshi; Tsuchizawa, Tai; Nishi, Hidetaka; Hatori, Nobuaki; Noguchi, Masataka; Nakamura, Takahiro; Takemasa, Keizo; Sugawara, Mitsuru; Arakawa, Yasuhiko

    2016-09-01

    We report the first demonstration of a hybrid silicon quantum dot (QD) laser, evanescently coupled to a silicon waveguide. InAs/GaAs QD laser structures with thin AlGaAs lower cladding layers were transferred by direct wafer bonding onto silicon waveguides defining cavities with adiabatic taper structures and distributed Bragg reflectors. The laser operates at temperatures up to 115 °C under pulsed current conditions, with a characteristic temperature T 0 of 303 K near room temperature. Furthermore, by reducing the width of the GaAs/AlGaAs mesa down to 8 µm, continuous-wave operation is realized at 25 °C.

  11. Evanescent photosynthesis: exciting cyanobacteria in a surface-confined light field.

    PubMed

    Ooms, Matthew D; Sieben, Vincent J; Pierobon, Scott C; Jung, Erica E; Kalontarov, Michael; Erickson, David; Sinton, David

    2012-04-14

    The conversion of solar energy to chemical energy useful for maintaining cellular function in photosynthetic algae and cyanobacteria relies critically on light delivery to the microorganisms. Conventional direct irradiation of a bulk suspension leads to non-uniform light distribution within a strongly absorbing culture, and related inefficiencies. The study of small colonies of cells in controlled microenvironments would benefit from control over wavelength, intensity, and location of light energy on the scale of the microorganism. Here we demonstrate that the evanescent light field, confined near the surface of a waveguide, can be used to direct light into cyanobacteria and successfully drive photosynthesis. The method is enabled by the synergy between the penetration depth of the evanescent field and the size of the photosynthetic bacterium, both on the order of micrometres. Wild type Synechococcus elongatus (ATCC 33912) cells are exposed to evanescent light generated through total internal reflection of red (λ = 633 nm) light on a prism surface. Growth onset is consistently observed at intensity levels of 79 ± 10 W m(-2), as measured 1 μm from the surface, and 60 ± 8 W m(-2) as measured by a 5 μm depthwise average. These threshold values agree well with control experiments and literature values based on direct irradiation with daylight. In contrast, negligible growth is observed with evanescent light penetration depths less than the minor dimension of the rod-like bacterium (achieved at larger light incident angles). Collectively these results indicate that evanescent light waves can be used to tailor and direct light into cyanobacteria, driving photosynthesis.

  12. Optical phased arrays with evanescently-coupled antennas

    DOEpatents

    Sun, Jie; Watts, Michael R; Yaacobi, Ami; Timurdogan, Erman

    2015-03-24

    An optical phased array formed of a large number of nanophotonic antenna elements can be used to project complex images into the far field. These nanophotonic phased arrays, including the nanophotonic antenna elements and waveguides, can be formed on a single chip of silicon using complementary metal-oxide-semiconductor (CMOS) processes. Directional couplers evanescently couple light from the waveguides to the nanophotonic antenna elements, which emit the light as beams with phases and amplitudes selected so that the emitted beams interfere in the far field to produce the desired pattern. In some cases, each antenna in the phased array may be optically coupled to a corresponding variable delay line, such as a thermo-optically tuned waveguide or a liquid-filled cell, which can be used to vary the phase of the antenna's output (and the resulting far-field interference pattern).

  13. Biotoxin Detection Using Cell-Based Sensors

    PubMed Central

    Banerjee, Pratik; Kintzios, Spyridon; Prabhakarpandian, Balabhaskar

    2013-01-01

    Cell-based biosensors (CBBs) utilize the principles of cell-based assays (CBAs) by employing living cells for detection of different analytes from environment, food, clinical, or other sources. For toxin detection, CBBs are emerging as unique alternatives to other analytical methods. The main advantage of using CBBs for probing biotoxins and toxic agents is that CBBs respond to the toxic exposures in the manner related to actual physiologic responses of the vulnerable subjects. The results obtained from CBBs are based on the toxin-cell interactions, and therefore, reveal functional information (such as mode of action, toxic potency, bioavailability, target tissue or organ, etc.) about the toxin. CBBs incorporate both prokaryotic (bacteria) and eukaryotic (yeast, invertebrate and vertebrate) cells. To create CBB devices, living cells are directly integrated onto the biosensor platform. The sensors report the cellular responses upon exposures to toxins and the resulting cellular signals are transduced by secondary transducers generating optical or electrical signals outputs followed by appropriate read-outs. Examples of the layout and operation of cellular biosensors for detection of selected biotoxins are summarized. PMID:24335754

  14. Sensor apparatus using an electrochemical cell

    DOEpatents

    Thakur, Mrinal

    2003-07-01

    A method for sensing mechanical quantities such as force, stress, strain, pressure and acceleration is disclosed. This technology is based on a change in the electrochemically generated voltage (electromotive force) with application of force, stress, strain, pressure or acceleration. The change in the voltage is due to a change in the internal resistance of the electrochemical cell with a change in the relative position or orientation of the electrodes (anode and cathode) in the cell. The signal to be detected (e.g. force, stress, strain, pressure or acceleration) is applied to one of the electrodes to cause a change in the relative position or orientation between the electrodes. Various materials, solid, semisolid, gel, paste or liquid can be utilized as the electrolyte. The electrolyte must be an ion conductor. The examples of solid electrolytes include specific polymer conductors, polymer composites, ion conducting glasses and ceramics. The electrodes are made of conductors such as metals with dissimilar electro negativities. Significantly enhanced sensitivities, up to three orders of magnitude higher than that of comparable commercial sensors, are obtained. The materials are substantially less expensive than commercially used materials for mechanical sensors. An apparatus for sensing such mechanical quantities using materials such as doped 1,4 cis-polyisopropene and nafion. The 1,4 cis-polyisopropene may be doped with lithium perchlorate or iodine. The output voltage signal increases with an increase of the sensing area for a given stress. The device can be used as an intruder alarm, among other applications.

  15. Sensor apparatus using an electrochemical cell

    DOEpatents

    Thakur, Mrinal

    2002-01-01

    A novel technology for sensing mechanical quantities such as force, stress, strain, pressure and acceleration has been invented. This technology is based on a change in the electrochemically generated voltage (electromotive force) with application of force, stress, strain, pressure or acceleration. The change in the voltage is due to a change in the internal resistance of the electrochemical cell with a change in the relative position or orientation of the electrodes (anode and cathode) in the cell. The signal to be detected (e.g. force, stress, strain, pressure or acceleration) is applied to one of the electrodes to cause a change in the relative position or orientation between the electrodes. Various materials, solid, semisolid, gel, paste or liquid can be utilized as the electrolyte. The electrolyte must be an ion conductor. The examples of solid electrolytes include specific polymer conductors, polymer composites, ion conducting glasses and ceramics. The electrodes are made of conductors such as metals with dissimilar electronegativities. Significantly enhanced sensitivities, up to three orders of magnitude higher than that of comparable commercial sensors, are obtained. The materials are substantially less expensive than commercially used materials for mechanical sensors.

  16. IR fiber-optic evanescent wave spectroscopy (FEWS) for sensing applications (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Katzir, Abraham

    2016-03-01

    We developed crystalline AgClBr fibers of diameters 0.7-0.9mm that are flexible, non-toxic, insoluble in water and highly transparent between 4-15µm. We used these fibers for various sensing applications. Highly sensitive absorption measurements in the mid-IR may be carried out by Fiber-optic Evanescent Wave Spectroscopy (FEWS). A typical FEWS system is based on three mid-IR components: a tunable source, a detector and a AgClBr fiber sensor that is brought in contact with the samples. We used FTIR spectrometers or tunable gas lasers or quantum cascade lasers (QCLs) as mid-IR sources. We used this FEWS system for measurements on gases, liquids and solids. In particular we used it for several biomedical applications. Measurements in vivo: (1) Early detection of skin diseases (e.g. melanoma). (2) Measurements on cells and bacteria. (3) Measurements on cornea. Measurements in vitro: (4) Characterization of urinary and biliary stones. (5) Blood measurements. The FEWS method is simple, inexpensive and does not require sample processing. It would be useful for diagnostic measurements on the outer part of the body of a patient, as well as for endoscopic measurements. It would also useful for measurements on tissue samples removed from the body. In addition we develop Scanning Near-field Infrared Microscope that will be used for spectral imaging with sub-wavelength resolution in the mid-IR. The various AgClBr fiber-optic sensors are expected to be important diagnostic tools at the hand of physicians in the future.

  17. The evanescent wavefield part of a cylindrical vector beam

    PubMed Central

    Chen, Rui-Pin; Li, Guoqiang

    2013-01-01

    The evanescent wave of the cylindrical vector field is analyzed using the vector angular spectrum of the electromagnetic beam. Comparison between the contributions of the TE and TM terms of both the propagating and the evanescent waves associated with the cylindrical vector field in free space is demonstrated. The physical pictures of the evanescent wave and the propagating wave are well illustrated from the vectorial structure, which provides a new approach to manipulating laser beams by choosing the states of polarization in the cross-section of the field. PMID:24104116

  18. Analytical scanning evanescent microwave microscope and control stage

    DOEpatents

    Xiang, Xiao-Dong; Gao, Chen; Duewer, Fred; Yang, Hai Tao; Lu, Yalin

    2009-06-23

    A scanning evanescent microwave microscope (SEMM) that uses near-field evanescent electromagnetic waves to probe sample properties is disclosed. The SEMM is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The SEMM has the ability to map dielectric constant, loss tangent, conductivity, electrical impedance, and other electrical parameters of materials. Such properties are then used to provide distance control over a wide range, from to microns to nanometers, over dielectric and conductive samples for a scanned evanescent microwave probe, which enable quantitative non-contact and submicron spatial resolution topographic and electrical impedance profiling of dielectric, nonlinear dielectric and conductive materials. The invention also allows quantitative estimation of microwave impedance using signals obtained by the scanned evanescent microwave probe and quasistatic approximation modeling. The SEMM can be used to measure electrical properties of both dielectric and electrically conducting materials.

  19. Analytical scanning evanescent microwave microscope and control stage

    DOEpatents

    Xiang, Xiao-Dong; Gao, Chen; Duewer, Fred; Yang, Hai Tao; Lu, Yalin

    2013-01-22

    A scanning evanescent microwave microscope (SEMM) that uses near-field evanescent electromagnetic waves to probe sample properties is disclosed. The SEMM is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The SEMM has the ability to map dielectric constant, loss tangent, conductivity, electrical impedance, and other electrical parameters of materials. Such properties are then used to provide distance control over a wide range, from to microns to nanometers, over dielectric and conductive samples for a scanned evanescent microwave probe, which enable quantitative non-contact and submicron spatial resolution topographic and electrical impedance profiling of dielectric, nonlinear dielectric and conductive materials. The invention also allows quantitative estimation of microwave impedance using signals obtained by the scanned evanescent microwave probe and quasistatic approximation modeling. The SEMM can be used to measure electrical properties of both dielectric and electrically conducting materials.

  20. Evanescent wave excited luminescence from levitated quantum dot modified colloids.

    PubMed

    Everett, W Neil; Beckham, Richard E; Meissner, Kenith; Bevan, Michael A

    2007-08-14

    Evanescent wave excited luminescence of quantum dot modified polystyrene (QDPS) colloids is investigated to measure potential energy profiles of QDPS colloids electrostatically levitated above a planar glass surface. Luminescence is characterized for three different-sized PS colloids modified with three different-sized QDs using confocal microscopy, emission spectra, flow cytometry, and temporal measurements of levitated and deposited colloids. Colloid-surface potential energy profiles constructed from scattering and luminescence intensity data display excellent agreement with each other, theoretical predictions, and independently measured parameters. QDPS luminescence intensity is indirectly confirmed to have an exponential dependence on height similar to conventional colloidal evanescent wave scattering. Our findings indicate that evanescent wave excited QDPS luminescence could enable total internal reflection microscopy measurements of index-matched hard spheres, multiple specific biomolecular interactions via spectral multiplexing, enhanced morphology-dependent resonance modes, and integrated evanescent wave-video-confocal microscopy experiments not possible with scattering.

  1. Thermo-acoustic engineering of silicon microresonators via evanescent waves

    SciTech Connect

    Tabrizian, R.; Ayazi, F.

    2015-06-29

    A temperature-compensated silicon micromechanical resonator with a quadratic temperature characteristic is realized by acoustic engineering. Energy-trapped resonance modes are synthesized by acoustic coupling of propagating and evanescent extensional waves in waveguides with rectangular cross section. Highly different temperature sensitivity of propagating and evanescent waves is used to engineer the linear temperature coefficient of frequency. The resulted quadratic temperature characteristic has a well-defined turn-over temperature that can be tailored by relative energy distribution between propagating and evanescent acoustic fields. A 76 MHz prototype is implemented in single crystal silicon. Two high quality factor and closely spaced resonance modes, created from efficient energy trapping of extensional waves, are excited through thin aluminum nitride film. Having different evanescent wave constituents and energy distribution across the device, these modes show different turn over points of 67 °C and 87 °C for their quadratic temperature characteristic.

  2. Platform for a Hydrocarbon Exhaust Gas Sensor Utilizing a Pumping Cell and a Conductometric Sensor

    PubMed Central

    Biskupski, Diana; Geupel, Andrea; Wiesner, Kerstin; Fleischer, Maximilian; Moos, Ralf

    2009-01-01

    Very often, high-temperature operated gas sensors are cross-sensitive to oxygen and/or they cannot be operated in oxygen-deficient (rich) atmospheres. For instance, some metal oxides like Ga2O3 or doped SrTiO3 are excellent materials for conductometric hydrocarbon detection in the rough atmosphere of automotive exhausts, but have to be operated preferably at a constant oxygen concentration. We propose a modular sensor platform that combines a conductometric two-sensor-setup with an electrochemical pumping cell made of YSZ to establish a constant oxygen concentration in the ambient of the conductometric sensor film. In this paper, the platform is introduced, the two-sensor-setup is integrated into this new design, and sensing performance is characterized. Such a platform can be used for other sensor principles as well. PMID:22423212

  3. Quantifying GFP Diffusion in Escherichia coli by Using Continuous Photobleaching with Evanescent Illumination

    PubMed Central

    Slade, Kristin M.; Steele, Bridgett L.; Pielak, Gary J.; Thompson, Nancy L.

    2009-01-01

    Fluorescence recovery after photobleaching and fluorescence correlation spectroscopy are the primary means for studying translational diffusion in biological systems. Both techniques, however, present numerous obstacles for measuring translational mobility in structures only slightly larger than optical resolution. We report a new method using through-prism total internal reflection fluorescence microscopy with continuous photobleaching (TIR-CP) to overcome these obstacles. Small structures, such as prokaryotic cells or isolated eukaryotic organelles, containing fluorescent molecules are adhered to a surface. This surface is continuously illuminated by an evanescent wave created by total internal reflection. The characteristic length describing the decay of the evanescent intensity with distance from the surface is smaller than the structures. The fluorescence decay rate resulting from continuous evanescent illumination is monitored as a function of the excitation intensity. The data at higher excitation intensities provide apparent translational diffusion coefficients for the fluorescent molecules within the structures because the decay results from two competing processes (the intrinsic photobleaching propensity and diffusion in the small structures). We present the theoretical basis for the technique and demonstrate its applicability by measuring the diffusion coefficient, 6.3 ± 1.1 µm2/sec, of green fluorescent protein (GFP) in Escherichia coli cells. PMID:19296673

  4. Fluorometer with a quartz-rod waveguide-integrating sphere configuration to measure evanescent-field luminescence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A fluorometer was designed to measure evanescent-field luminescence. A quartz-rod waveguide (d = 2 mm) was installed coaxally inside a cylindrical flow-through cell (id = 2.3 mm, od = 6.3 mm, l = 116 mm). An excitation beam from a UV LED or a miniature xenon flashlamp was focused by a ball lens and ...

  5. Electrochemical sensor for monitoring electrochemical potentials of fuel cell components

    DOEpatents

    Kunz, Harold R.; Breault, Richard D.

    1993-01-01

    An electrochemical sensor comprised of wires, a sheath, and a conduit can be utilized to monitor fuel cell component electric potentials during fuel cell shut down or steady state. The electrochemical sensor contacts an electrolyte reservoir plate such that the conduit wicks electrolyte through capillary action to the wires to provide water necessary for the electrolysis reaction which occurs thereon. A voltage is applied across the wires of the electrochemical sensor until hydrogen evolution occurs at the surface of one of the wires, thereby forming a hydrogen reference electrode. The voltage of the fuel cell component is then determined with relation to the hydrogen reference electrode.

  6. Micromachined force sensors for the study of cell mechanics

    NASA Astrophysics Data System (ADS)

    Yang, Shengyuan; Saif, Taher

    2005-04-01

    A technique using micromachined mechanical force sensors to measure the force response of living cells is introduced. The force sensors consist of a probe and flexible beams. The probe is used to indent and stretch the cells, and the flexible beams are used to measure the cell force response. The stiffness of the sensors is designed at several nanonewtons per micrometer, but can be varied over a wide range. The sensors are fabricated by the SCREAM process. The deformation of the cells and the deflection of flexible beams are measured by an optical microscope coupled with a charge-coupled device camera. Experimental demonstrations show the feasibility, simplicity, and versatility of this technique. It addresses several disadvantages of existing related techniques, and is complementary to many of them. We expect that this new technique will attract significant attention and be employed much more in the study of cell mechanics.

  7. Evanescent-wave amplification studied using a bilayer periodic circuit structure and its effective medium model

    NASA Astrophysics Data System (ADS)

    Liu, Ruopeng; Zhao, Bo; Lin, Xian Qi; Cheng, Qiang; Cui, Tie Jun

    2007-03-01

    In this paper, we present both theoretical analysis and experimental verification of evanescent-wave amplification by using a bilayer periodic circuit structure and its effective medium model. We propose a series-shunt capacitor (C-C) structure to simulate a magnetic plasma, whose permittivity is positive and permeability is negative, and a series-shunt inductor (L-L) structure to simulate an electric plasma, whose permittivity is negative and permeability is positive, in which the structure cells are not required to be electrically small. In addition, we derive and define an effective permittivity and permeability for the C-C and L-L structures in closed forms, which are completely different from the published ones. When the two structures are cascaded together to form a bilayer structure, we show that evanescent waves which exist in two single layers independently can be amplified exponentially if a certain resonant condition is satisfied. Such a resonant condition is equivalent to the antimatching condition for the permittivity and permeability of the effectively electric and magnetic plasmas. To show the accuracy of this equivalent medium model, we compare both circuit-simulation results for the C-C and L-L structures and theoretical-prediction results for the effective magnetic and electric plasmas, which have excellent agreement. Finally, we design an experiment using lumped capacitors and inductors mounted on a printed circuit board to verify the amplification of evanescent waves sufficiently. The measurement results have good agreement with the simulation results.

  8. Biomimetic chemical sensors using bioengineered olfactory and taste cells.

    PubMed

    Du, Liping; Zou, Ling; Zhao, Luhang; Wang, Ping; Wu, Chunsheng

    2014-01-01

    Biological olfactory and taste systems are natural chemical sensing systems with unique performances for the detection of environmental chemical signals. With the advances in olfactory and taste transduction mechanisms, biomimetic chemical sensors have achieved significant progress due to their promising prospects and potential applications. Biomimetic chemical sensors exploit the unique capability of biological functional components for chemical sensing, which are often sourced from sensing units of biological olfactory or taste systems at the tissue level, cellular level, or molecular level. Specifically, at the cellular level, there are mainly two categories of cells have been employed for the development of biomimetic chemical sensors, which are natural cells and bioengineered cells, respectively. Natural cells are directly isolated from biological olfactory and taste systems, which are convenient to achieve. However, natural cells often suffer from the undefined sensing properties and limited amount of identical cells. On the other hand, bioengineered cells have shown decisive advantages to be applied in the development of biomimetic chemical sensors due to the powerful biotechnology for the reconstruction of the cell sensing properties. Here, we briefly summarized the most recent advances of biomimetic chemical sensors using bioengineered olfactory and taste cells. The development challenges and future trends are discussed as well.

  9. Biomimetic chemical sensors using bioengineered olfactory and taste cells

    PubMed Central

    Du, Liping; Zou, Ling; Zhao, Luhang; Wang, Ping; Wu, Chunsheng

    2014-01-01

    Biological olfactory and taste systems are natural chemical sensing systems with unique performances for the detection of environmental chemical signals. With the advances in olfactory and taste transduction mechanisms, biomimetic chemical sensors have achieved significant progress due to their promising prospects and potential applications. Biomimetic chemical sensors exploit the unique capability of biological functional components for chemical sensing, which are often sourced from sensing units of biological olfactory or taste systems at the tissue level, cellular level, or molecular level. Specifically, at the cellular level, there are mainly two categories of cells have been employed for the development of biomimetic chemical sensors, which are natural cells and bioengineered cells, respectively. Natural cells are directly isolated from biological olfactory and taste systems, which are convenient to achieve. However, natural cells often suffer from the undefined sensing properties and limited amount of identical cells. On the other hand, bioengineered cells have shown decisive advantages to be applied in the development of biomimetic chemical sensors due to the powerful biotechnology for the reconstruction of the cell sensing properties. Here, we briefly summarized the most recent advances of biomimetic chemical sensors using bioengineered olfactory and taste cells. The development challenges and future trends are discussed as well. PMID:25482234

  10. Biochemical affinity sensing systems based on luminescence generation in the evanescent field of optical waveguides

    NASA Astrophysics Data System (ADS)

    Duveneck, Gert L.; Oroszlan, Peter; Abel, A. P.; Klee, B.; Steiner, V.; Ehrat, Markus; Gygax, D.; Widmer, H. M.

    1995-01-01

    We have developed a (bio)chemical analysis system based on luminescence generation and detection in the evanescent field associated with light guiding in an optical fiber. Our intention was directed towards optimization of not only the sensor, including the sensor handling and the immobilization of biochemical recognition elements, but also of the assay chemistry, with special emphasis on methods used for sensor regeneration, of the fluidic system, and of the experimental control software. Goals of this optimization process were not only to achieve high sensitivity, reproducibility and the related precision of the results, but also maximum regenerability of the sensors and system flexibility for a variety of different applications. Four examples of different bioaffinity assays, established on our sensor system, are presented: a competitive immunoassay for atrazine, a sandwich immunoassay for hirudin, a DNA hybridization assay, and first studies for the development of sensors based on membrane- bound receptors. In the atrazine assay, the sensor could be regenerated more than 300 times. In the hybridization assay, a detection limit of 7.5 multiplied by 10-14 M complementary fluorescein-labeled DNA was achieved. The performance of our system is compared with an established enzyme-linked immunosorbent assay (ELISA) on the example of the hirudin assay. In the concluding section of this paper, advantages and disadvantages of our fiberoptic, luminescence-based system, compared with commercialized systems, based on detection of changes of the effective refractive index, are discussed.

  11. Linearly decayed evanescent optical field in planar refractive index well

    NASA Astrophysics Data System (ADS)

    Liu, Jianhua; Tao, Li

    2017-04-01

    Evanescent optical field with linearly decaying profile is theoretically analyzed at the critical angle of incidence in a planar structure of one dimensional refractive index well (RIW). The linearity of the evanescent field is due to the presence of the second refractive index barrier, which also shifts the position of total internal reflection (TIR) away from the critical angle. The decaying rate is determined by the refractive indices of the two barriers, as well as the width of the well. With this linearly decayed evanescent field (LDEF), various profiles across the well, for example uniform one, can be formed via appropriate combination of the LDEFs, which can promote new applications in fields of material analysis and sensing in the molecular scale.

  12. Perfluorinated plastic optical fiber tapers for evanescent wave sensing.

    PubMed

    Gravina, Roberto; Testa, Genni; Bernini, Romeo

    2009-01-01

    In this work we describe the fabrication and the characterization of perfluorinated plastic-cladded optical fiber tapers. The heat-and-pull procedure has been used to fabricate symmetric tapers. Devices with different taper ratio have been produced and the repeatability of the process has been verified. The very low refractive indexes of the core-cladding perfluorinated polymers (n = 1.35-1.34) permit a strong enhancement of the evanescent wave power fraction in aqueous environments (n = 1.33), making them very attractive for evanescent wave sensing. The tapers have been characterized carrying out evanescent field absorbance measurements with different concentrations of methylene blue in water and fluorescence collection measurements in an aqueous solution containing Cy5 dye. A good sensitivity, tightly related to the low refractive index of the core-cladding materials and the geometrical profile, has been shown.

  13. Amplification of acoustic evanescent waves using metamaterial slabs.

    PubMed

    Park, Choon Mahn; Park, Jong Jin; Lee, Seung Hwan; Seo, Yong Mun; Kim, Chul Koo; Lee, Sam H

    2011-11-04

    We amplified acoustic evanescent waves using metamaterial slabs with a negative effective density. For the amplifying effect of the slab to overcome the dissipation, it is necessary that the imaginary part of the effective density is much smaller than the real part, a condition not satisfied so far. We report the construction of membrane-based two-dimensional negative-density metamaterials which exhibited remarkably small dissipation. Using a slab of this metamaterial we realized a 17-fold net amplitude gain at a remote distance from the evanescent wave source. Potential applications include acoustic superlensing.

  14. Evanescent Wave-Assisted Symmetry Breaking of Gold Dipolar Nanoantennas

    PubMed Central

    Yang, Jhen-Hong; Chen, Kuo-Ping

    2016-01-01

    Symmetry-breaking and scattering cancellation were observed in the dark-mode resonance of dipolar gold nanoantennas (NAs) on glass substrates coupled with oblique incidence and total internal reflection. With the assistance of evanescent waves, the coupling efficiency was twice as strong when the incidence angle was larger than the critical angle. The Hamiltonian equation and absorption spectra were used to analyze the hybridization model of symmetric dipolar gold NAs. The antibonding mode could be coupled successfully by both transverse-magnetic (TM) and transverse-electric (TE) polarizations to NAs when the dimers orientation is parallel to the propagation direction of evanescent waves. PMID:27581766

  15. Evanescent Wave-Assisted Symmetry Breaking of Gold Dipolar Nanoantennas

    NASA Astrophysics Data System (ADS)

    Yang, Jhen-Hong; Chen, Kuo-Ping

    2016-09-01

    Symmetry-breaking and scattering cancellation were observed in the dark-mode resonance of dipolar gold nanoantennas (NAs) on glass substrates coupled with oblique incidence and total internal reflection. With the assistance of evanescent waves, the coupling efficiency was twice as strong when the incidence angle was larger than the critical angle. The Hamiltonian equation and absorption spectra were used to analyze the hybridization model of symmetric dipolar gold NAs. The antibonding mode could be coupled successfully by both transverse-magnetic (TM) and transverse-electric (TE) polarizations to NAs when the dimers orientation is parallel to the propagation direction of evanescent waves.

  16. Galvanic Cell Type Sensor for Soil Moisture Analysis.

    PubMed

    Gaikwad, Pramod; Devendrachari, Mruthyunjayachari Chattanahalli; Thimmappa, Ravikumar; Paswan, Bhuneshwar; Raja Kottaichamy, Alagar; Makri Nimbegondi Kotresh, Harish; Thotiyl, Musthafa Ottakam

    2015-07-21

    Here we report the first potentiometric sensor for soil moisture analysis by bringing in the concept of Galvanic cells wherein the redox energies of Al and conducting polyaniline are exploited to design a battery type sensor. The sensor consists of only simple architectural components, and as such they are inexpensive and lightweight, making it suitable for on-site analysis. The sensing mechanism is proved to be identical to a battery type discharge reaction wherein polyaniline redox energy changes from the conducting to the nonconducting state with a resulting voltage shift in the presence of soil moisture. Unlike the state of the art soil moisture sensors, a signal derived from the proposed moisture sensor is probe size independent, as it is potentiometric in nature and, hence, can be fabricated in any shape or size and can provide a consistent output signal under the strong aberration conditions often encountered in soil moisture analysis. The sensor is regenerable by treating with 1 M HCl and can be used for multiple analysis with little read out hysteresis. Further, a portable sensor is fabricated which can provide warning signals to the end user when the moisture levels in the soil go below critically low levels, thereby functioning as a smart device. As the sensor is inexpensive, portable, and potentiometric, it opens up avenues for developing effective and energy efficient irrigation strategies, understanding the heat and water transfer at the atmosphere-land interface, understanding soil mechanics, forecasting the risk of natural calamities, and so on.

  17. Infrared Fiber Evanescent Wave Spectroscopy For In-Situ Monitoring Of Chemical Processes

    NASA Astrophysics Data System (ADS)

    Margalit, Eli; Dodiuk, H.; Kosower, Edward M.; Katzir, Abraham

    1989-06-01

    A silver halide infrared fiber-optic evanescent wave spectroscopic technique for in-situ monitoring of chemical processes and surface analysis is described. Samples are spread onto a fiber contained in a teflon-lined cell. Attenuated total internal reflectance (AIR) measurement with a Fourier transform infrared (FTIR) spectrometer yields spectra at various stages of a process (for example, the monitoring of adhesive curing and coupling agent polymerization). Changes in known spectroscopic features may be recognized in films as thin as a monolayer. The advantages and limitations of this surface analysis technique are discussed.

  18. Transverse multipolar light-matter couplings in evanescent waves

    NASA Astrophysics Data System (ADS)

    Fernandez-Corbaton, Ivan; Zambrana-Puyalto, Xavier; Bonod, Nicolas; Rockstuhl, Carsten

    2016-11-01

    We present an approach to study the interaction between matter and evanescent fields. The approach is based on the decomposition of evanescent plane waves into multipoles of well-defined angular-momentum transverse to both decay and propagation directions. We use the approach to identify the origin of the recently observed directional coupling of emitters into guided modes, and of the opposite Zeeman state excitation of atoms near a fiber. We explain how to rigorously quantify both effects and show that the directionality and the difference in excitation rates grow exponentially with the multipolar order of the light-matter interaction. We also use the approach to study and maximize the transverse torque exerted by an evanescent plane wave onto a given spherical absorbing particle. All the obtained physical insights can be traced back to the two main features of the decomposition of evanescent plane waves into transverse multipolar modes: A polarization independent exponential dominance of modes with large transverse angular momentum, and a polarization-controlled parity selection rule.

  19. Selection of optimal sensors for predicting performance of polymer electrolyte membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Mao, Lei; Jackson, Lisa

    2016-10-01

    In this paper, sensor selection algorithms are investigated based on a sensitivity analysis, and the capability of optimal sensors in predicting PEM fuel cell performance is also studied using test data. The fuel cell model is developed for generating the sensitivity matrix relating sensor measurements and fuel cell health parameters. From the sensitivity matrix, two sensor selection approaches, including the largest gap method, and exhaustive brute force searching technique, are applied to find the optimal sensors providing reliable predictions. Based on the results, a sensor selection approach considering both sensor sensitivity and noise resistance is proposed to find the optimal sensor set with minimum size. Furthermore, the performance of the optimal sensor set is studied to predict fuel cell performance using test data from a PEM fuel cell system. Results demonstrate that with optimal sensors, the performance of PEM fuel cell can be predicted with good quality.

  20. Nanoparticle PEBBLE sensors in live cells and in vivo.

    PubMed

    Lee, Yong-Eun Koo; Smith, Ron; Kopelman, Raoul

    2009-01-01

    Nanoparticle sensors have been developed for real-time imaging and dynamic monitoring, both in live cells and in vivo, of molecular and ionic components, constructs, forces, and dynamics observed during biological, chemical, and physical processes. With their biocompatible small size and inert matrix, nanoparticle sensors have been successfully applied to noninvasive real-time measurements of analytes and fields in cells and in rodents, with spatial, temporal, physical, and chemical resolution. This review describes the diverse designs of nanoparticle sensors for ions and small molecules, physical fields, and biological features, as well as the characterization, properties, and applications of these nanosensors to in vitro and in vivo measurements. Their floating as well as localization abilities in biological media are captured by the acronym PEBBLE: photonic explorer for bioanalysis with biologically localized embedding.

  1. Evanescent-wave comb spectroscopy of liquids with strongly dispersive optical fiber cavities

    NASA Astrophysics Data System (ADS)

    Avino, S.; Giorgini, A.; Salza, M.; Fabian, M.; Gagliardi, G.; De Natale, P.

    2013-05-01

    We demonstrate evanescent-wave fiber cavity-enhanced spectroscopy in the liquid phase using a near-infrared frequency comb. Exploiting strong fiber-dispersion effects, we show that liquid absorption spectra can be recorded without any external dispersive element. The fiber cavity is used both as sensor and spectrometer. The resonance modes are frequency locked to the comb teeth while the cavity photon lifetime is measured over 155 nm, from 1515 nm to 1670 nm, where absorption bands of liquid polyamines are detected as a proof of concept. Our fiber spectrometer lends itself to in situ, real-time chemical analysis in environmental monitoring, biomedical assays, and micro-opto-fluidic systems.

  2. Optical waveguides for evanescent field sensing

    NASA Astrophysics Data System (ADS)

    Rehouma, F.; Persegol, D.; Kevorkian, A.

    1994-09-01

    A novel method based on the control of the topography of the guide during its elaboration was presented. This new method aimed to contribute to the working principle of integrated-optics sensors. The proposed technique is easy to use and allows to bury different regions of ion-exchange waveguides selectively. The surface interaction length of the component and the losses of the structure can be controlled by the width and the tilt angle of the mask. Moreover, the method presented a combination of numerous advantages.

  3. CMOS Cell Sensors for Point-of-Care Diagnostics

    PubMed Central

    Adiguzel, Yekbun; Kulah, Haluk

    2012-01-01

    The burden of health-care related services in a global era with continuously increasing population and inefficient dissipation of the resources requires effective solutions. From this perspective, point-of-care diagnostics is a demanded field in clinics. It is also necessary both for prompt diagnosis and for providing health services evenly throughout the population, including the rural districts. The requirements can only be fulfilled by technologies whose productivity has already been proven, such as complementary metal-oxide-semiconductors (CMOS). CMOS-based products can enable clinical tests in a fast, simple, safe, and reliable manner, with improved sensitivities. Portability due to diminished sensor dimensions and compactness of the test set-ups, along with low sample and power consumption, is another vital feature. CMOS-based sensors for cell studies have the potential to become essential counterparts of point-of-care diagnostics technologies. Hence, this review attempts to inform on the sensors fabricated with CMOS technology for point-of-care diagnostic studies, with a focus on CMOS image sensors and capacitance sensors for cell studies. PMID:23112587

  4. CMOS cell sensors for point-of-care diagnostics.

    PubMed

    Adiguzel, Yekbun; Kulah, Haluk

    2012-01-01

    The burden of health-care related services in a global era with continuously increasing population and inefficient dissipation of the resources requires effective solutions. From this perspective, point-of-care diagnostics is a demanded field in clinics. It is also necessary both for prompt diagnosis and for providing health services evenly throughout the population, including the rural districts. The requirements can only be fulfilled by technologies whose productivity has already been proven, such as complementary metal-oxide-semiconductors (CMOS). CMOS-based products can enable clinical tests in a fast, simple, safe, and reliable manner, with improved sensitivities. Portability due to diminished sensor dimensions and compactness of the test set-ups, along with low sample and power consumption, is another vital feature. CMOS-based sensors for cell studies have the potential to become essential counterparts of point-of-care diagnostics technologies. Hence, this review attempts to inform on the sensors fabricated with CMOS technology for point-of-care diagnostic studies, with a focus on CMOS image sensors and capacitance sensors for cell studies.

  5. Membrane fluidity sensoring microbial fuel cell.

    PubMed

    Choi, Youngjin; Jung, Eunkyoung; Kim, Sunghyun; Jung, Seunho

    2003-04-01

    A study has been performed to examine the effect of temperature and ethanolic stresses on the coulombic efficiency of a microbial fuel cell. The conventional-type fuel cell containing Gram-negative bacteria, Proteus vulgaris, was investigated as a model system. From current output measurements, it was found that the coulombic yields were altered by environmental stresses such as temperature shock or ethanol treatment to the bacteria. While high-temperature or ethanolic shock led to a remarkable decrement in coulombic output, the low-temperature shock induced a slight increase in microbial fuel cell efficiency. These results indicate that the membrane fluidity is affected considerably by environmental stress, which in turn affects the electron transfer process through the bacterial cell membrane to and from the electrode. This interpretation was confirmed by the cyclic voltammetric study of a mediator on an electrode surface modified with the lipids extracted from the membrane of P. vulgaris under the given stress. Markedly different electrochemical behaviors were observed depending on the environmental stress. A reciprocal relationship between coulomb output and the ratio of saturation/unsaturation of fatty acids has been observed. This is the first report, to our knowledge, that the structural adaptation of membrane fatty acids in response to the environmental shock can regulate the coulombic efficiency of a microbial fuel cell.

  6. Evanescent wave fluorescence biosensors: Advances of the last decade

    PubMed Central

    Taitt, Chris Rowe; Anderson, George P.; Ligler, Frances S.

    2015-01-01

    Biosensor development has been a highly dynamic field of research and has progressed rapidly over the past two decades. The advances have accompanied the breakthroughs in molecular biology, nanomaterial sciences, and most importantly computers and electronics. The subfield of evanescent wave fluorescence biosensors has also matured dramatically during this time. Fundamentally, this review builds on our earlier 2005 review. While a brief mention of seminal early work will be included, this current review will focus on new technological developments as well as technology commercialized in just the last decade. Evanescent wave biosensors have found a wide array applications ranging from clinical diagnostics to biodefense to food testing; advances in those applications and more are described herein. PMID:26232145

  7. Mechanical action of the transverse spin flows in evanescent fields

    NASA Astrophysics Data System (ADS)

    Angelsky, O. V.; Zenkova, C. Yu.; Maksymyak, P. P.; Maksymyak, A. P.; Ivansky, D. I.

    2016-12-01

    Mechanical action caused by the optical forces connected with the canonical momentum density associated with the local wavevector or Belifante's spin angular momentum, the helicity dependent and the helicity independent forces determined by spin momenta of different nature open attractive prospects to use optical structures for manipulating with minute quantities of matter that is of importance in nanophysics, nanooptics and nanotechnologies, precision chemistry and pharmacology and in numerous other areas. The main finding of our study consists in direct experimental demonstration of physical reality and mechanical action of recently discovered extraordinary transverse component of the spin angular momentum arising (in our case) in an evanescent light wave due to the total internal reflection of linearly polarized probing beam with azimuth 450 at the interface `birefringent plate-air', which is oriented perpendicularly to the wave vector of an evanescent wave.

  8. Evanescent radiation, quantum mechanics and the Casimir effect

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.

    1989-01-01

    An attempt to bridge the gap between classical and quantum mechanics and to explain the Casimir effect is presented. The general nature of chaotic motion is discussed from two points of view: the first uses catastrophe theory and strange attractors to describe the deterministic view of this motion; the underlying framework for chaos in these classical dynamic systems is their extreme sensitivity to initial conditions. The second interpretation refers to randomness associated with probabilistic dynamics, as for Brownian motion. The present approach to understanding evanescent radiation and its relation to the Casimir effect corresponds to the first interpretation, whereas stochastic electrodynamics corresponds to the second viewpoint. The nonlinear behavior of the electromagnetic field is also studied. This well-understood behavior is utilized to examine the motions of two orbiting charges and shows a closeness between the classical behavior and the quantum uncertainty principle. The evanescent radiation is used to help explain the Casimir effect.

  9. Manipulation of metallic nanoparticle with evanescent vortex Bessel beam.

    PubMed

    Rui, Guanghao; Wang, Xiaoyan; Cui, Yiping

    2015-10-05

    In this work, we propose a novel strategy to optically trap and manipulate metallic nanoparticles using evanescent vortex Bessel beam (EVBB). A versatile method is presented to generate evanescent Bessel beam with tunable optical angular momentum by focusing a radially polarized vortex beam onto a one-dimensional photonics band gap structure. The behavior of a metallic nanoparticle in the EVBB is numerically studied. We show that such particle can be stably trapped near the surface. The orbital angular momentum drives the metallic nanoparticle to orbit around the beam axis, and the direction of the orbital motion is controlled by the handedness of the helical phase front. The technique demonstrated in this work may open up new avenues for optical manipulation, and the non-contact tunable orbiting dynamics of the trapped particle may find important applications in higher resolution imaging techniques.

  10. Theory of Evanescent-Wave Johnson Noise in Qubit Devices

    DTIC Science & Technology

    2015-05-28

    metallic electrodes and leads. This random motion has both thermal and quantum components, though in most devices presently under investigation, the...Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 evanescent wave, Johnson noise, decoherence, metal surface REPORT DOCUMENTATION PAGE 11...ultimate source of these fluctuations is the random electric currents that are strongest in the metallic electrodes and leads. This random motion has both

  11. A novel microbial fuel cell sensor with biocathode sensing element.

    PubMed

    Jiang, Yong; Liang, Peng; Liu, Panpan; Wang, Donglin; Miao, Bo; Huang, Xia

    2017-03-02

    The traditional microbial fuel cell (MFC) sensor with bioanode as sensing element delivers limited sensitivity to toxicity monitoring, restricted application to only anaerobic and organic rich water body, and increased potential fault warning to the combined shock of organic matter/toxicity. In this study, the biocathode for oxygen reduction reaction was employed for the first time as the sensing element in MFC sensor for toxicity monitoring. The results shown that the sensitivity of MFC sensor with biocathode sensing element (7.4±2.0 to 67.5±4.0mA%(-1)cm(-2)) was much greater than that showed by bioanode sensing element (3.4±1.5 to 5.5±0.7mA%(-1)cm(-2)). The biocathode sensing element achieved the lowest detection limit reported to date using MFC sensor for formaldehyde detection (0.0005%), while the bioanode was more applicable for higher concentration (>0.0025%). There was a quicker response of biocathode sensing element with the increase of conductivity and dissolved oxygen (DO). The biocathode sensing element made the MFC sensor directly applied to clean water body monitoring, e.g., drinking water and reclaimed water, without the amending of background organic matter, and it also decreased the warning failure when challenged by a combined shock of organic matter/toxicity.

  12. Artificial magnetic field induced by an evanescent wave

    PubMed Central

    Mochol, Małgorzata; Sacha, Krzysztof

    2015-01-01

    Cold atomic gases are perfect laboratories for realization of quantum simulators. In order to simulate solid state systems in the presence of magnetic fields special effort has to be made because atoms are charge neutral. There are different methods for realization of artificial magnetic fields, that is the creation of specific conditions so that the motion of neutral particles mimics the dynamics of charged particles in an effective magnetic field. Here, we consider adiabatic motion of atoms in the presence of an evanescent wave. Theoretical description of the adiabatic motion involves artificial vector and scalar potentials related to the Berry phases. Due to the large gradient of the evanescent field amplitude, the potentials can be strong enough to induce measurable effects in cold atomic gases. We show that the resulting artificial magnetic field is able to induce vortices in a Bose-Einstein condensate trapped close to a surface of a prism where the evanescent wave is created. We also analyze motion of an atomic cloud released from a magneto-optical trap that falls down on the surface of the prism. The artificial magnetic field is able to reflect falling atoms that can be observed experimentally. PMID:25567430

  13. Batteryless, wireless sensor powered by a sediment microbial fuel cell.

    PubMed

    Donovan, Conrad; Dewan, Alim; Heo, Deukhyoun; Beyenal, Haluk

    2008-11-15

    Sediment microbial fuel cells (SMFCs) are considered to be an alternative renewable power source for remote monitoring. There are two main challenges to using SMFCs as power sources: 1) a SMFC produces a low potential at which most sensor electronics do not operate, and 2) a SMFC cannot provide continuous power, so energy from the SMFC must be stored and then used to repower sensor electronics intermittently. In this study, we developed a SMFC and a power management system (PMS) to power a batteryless, wireless sensor. A SMFC operating with a microbial anode and cathode, located in the Palouse River, Pullman, Washington, U.S.A., was used to demonstrate the utility of the developed system. The designed PMS stored microbial energy and then started powering the wireless sensor when the SMFC potential reached 320 mV. It continued powering until the SMFC potential dropped below 52 mV. The system was repowered when the SMFC potential increased to 320 mV, and this repowering continued as long as microbial reactions continued. We demonstrated that a microbial fuel cell with a microbial anode and cathode can be used as an effective renewable power source for remote monitoring using custom-designed electronics.

  14. Blood pH optrode based on evanescent waves and refractive index change

    NASA Astrophysics Data System (ADS)

    Hammarling, Krister; Hilborn, Jöns; Nilsson, Hans-Erik; Manuilskiy, Anatoliy

    2014-02-01

    Sensing pH in blood with an silica multimode optical fiber. This sensor is based on evanescent wave absorption and measures the change of the refractive index and absorption in a cladding made of a biocompatible Polymer. In contrast to many existing fiber optical sensors which are based upon different dyes or florescent material to sense the pH, here presents a solution where a part of the cladding is replaced with a Poly (β-amino ester) made of 1.4-Butanediol diacrylate, Piperazine, and Trimethylolpropane Triacrylate. Piperazine has the feature of changing its volume by swelling or shrinking in response to the pH level. This paper utilizes this dimension effect and measure the refractive index and the absorption of the cladding in respect to different pH-levels. The alteration of refractive index also causes a change in the absorption and therefore the output power changes as a function of the pH level. The sensor is sensitive to pH in a wide spectral range and light absorbency can be observed for wavelengths ranging from UV to far IR.

  15. Evanescent-Vacuum-Enhanced Photon-Exciton Coupling and Fluorescence Collection

    NASA Astrophysics Data System (ADS)

    Ren, Juanjuan; Gu, Ying; Zhao, Dongxing; Zhang, Fan; Zhang, Tiancai; Gong, Qihuang

    2017-02-01

    An evanescent optical mode existing in various nanophotonic structures always acts as a cavity mode rather than an electromagnetic vacuum in the study of cavity quantum electrodynamics (CQED). Here we show that taking the evanescent mode as an electromagnetic vacuum in which the nanocavity is located is possible through the optical mode design. The proposed evanescent vacuum enables us to enhance both the reversible photon-exciton interaction and fluorescence collection. By embedding the custom-designed plasmon nanocavity into the evanescent vacuum provided by a metallic or dielectric nanowire, the photon-exciton coupling coefficient can achieve 4.2 times that in vacuum due to the exponential decay of the evanescent wave, and spontaneously emitted photons with Rabi splitting can be guided by an evanescent wave with a collection efficiency of 47% at most. Electromagnetic vacuum engineering at subwavelength scale holds promise for controlling the light-matter interaction in quantum optics, CQED, and on-chip quantum information.

  16. Method and apparatus for enhanced evanescent fluorescence and color filtering using a high refractive index thin film coating

    DOEpatents

    Kao, Hung Pin; Schoeniger, Joseph; Yang, Nancy

    2001-01-01

    A technique for increasing the excitation and collection of evanescent fluorescence radiation emanating from a fiber optic sensor having a high refractive index (n.sub.r), dielectric thin film coating has been disclosed and described. The invention comprises a clad optical fiber core whose cladding is removed on a distal end, the distal end coated with a thin, non-porous, titanium dioxide sol-gel coating. It has been shown that such a fiber will exhibit increased fluorescence coupling due in part by 1) increasing the intensity of the evanescent field at the fiber core surface by a constructive interference effect on the propagating light, and 2) increasing the depth of penetration of the field in the sample. The interference effect created by the thin film imposes a wavelength dependence on the collection of the fluorescence and also suggests a novel application of thin films for color filtering as well as increasing collected fluorescence in fiber sensors. Collected fluorescence radiation increased by up to 6-fold over that of a bare fused silica fiber having a numerical aperture (N.A.) of O.6.

  17. Field comparison of optical and clark cell dissolved-oxygen sensors

    USGS Publications Warehouse

    Fulford, J.M.; Davies, W.J.; Garcia, L.

    2005-01-01

    Three multi-parameter water-quality monitors equipped with either Clark cell type or optical type dissolved-oxygen sensors were deployed for 30 days in a brackish (salinity <10 parts per thousand) environment to determine the sensitivity of the sensors to biofouling. The dissolved-oxygen sensors compared periodically to a hand-held dissolved oxygen sensor, but were not serviced or cleaned during the deployment. One of the Clark cell sensors and the optical sensor performed similarly during the deployment. The remaining Clark cell sensor was not aged correctly prior to deployment and did not perform as well as the other sensors. All sensors experienced substantial biofouling that gradually degraded the accuracy of the dissolved-oxygen measurement during the last half of the deployment period. Copyright ASCE 2005.

  18. Hydrogen peroxide regulates cell adhesion through the redox sensor RPSA.

    PubMed

    Vilas-Boas, Filipe; Bagulho, Ana; Tenente, Rita; Teixeira, Vitor H; Martins, Gabriel; da Costa, Gonçalo; Jerónimo, Ana; Cordeiro, Carlos; Machuqueiro, Miguel; Real, Carla

    2016-01-01

    To become metastatic, a tumor cell must acquire new adhesion properties that allow migration into the surrounding connective tissue, transmigration across endothelial cells to reach the blood stream and, at the site of metastasis, adhesion to endothelial cells and transmigration to colonize a new tissue. Hydrogen peroxide (H2O2) is a redox signaling molecule produced in tumor cell microenvironment with high relevance for tumor development. However, the molecular mechanisms regulated by H2O2 in tumor cells are still poorly known. The identification of H2O2-target proteins in tumor cells and the understanding of their role in tumor cell adhesion are essential for the development of novel redox-based therapies for cancer. In this paper, we identified Ribosomal Protein SA (RPSA) as a target of H2O2 and showed that RPSA in the oxidized state accumulates in clusters that contain specific adhesion molecules. Furthermore, we showed that RPSA oxidation improves cell adhesion efficiency to laminin in vitro and promotes cell extravasation in vivo. Our results unravel a new mechanism for H2O2-dependent modulation of cell adhesion properties and identify RPSA as the H2O2 sensor in this process. This work indicates that high levels of RPSA expression might confer a selective advantage to tumor cells in an oxidative environment.

  19. A new principle for low-cost hydrogen sensors for fuel cell technology safety

    SciTech Connect

    Liess, Martin

    2014-03-24

    Hydrogen sensors are of paramount importance for the safety of hydrogen fuel cell technology as result of the high pressure necessary in fuel tanks and its low explosion limit. I present a novel sensor principle based on thermal conduction that is very sensitive to hydrogen, highly specific and can operate on low temperatures. As opposed to other thermal sensors it can be operated with low cost and low power driving electronics. On top of this, as sensor element a modified standard of-the shelf MEMS thermopile IR-sensor can be used. The sensor principle presented is thus suited for the future mass markets of hydrogen fuel cell technology.S.

  20. A new principle for low-cost hydrogen sensors for fuel cell technology safety

    NASA Astrophysics Data System (ADS)

    Liess, Martin

    2014-03-01

    Hydrogen sensors are of paramount importance for the safety of hydrogen fuel cell technology as result of the high pressure necessary in fuel tanks and its low explosion limit. I present a novel sensor principle based on thermal conduction that is very sensitive to hydrogen, highly specific and can operate on low temperatures. As opposed to other thermal sensors it can be operated with low cost and low power driving electronics. On top of this, as sensor element a modified standard of-the shelf MEMS thermopile IR-sensor can be used. The sensor principle presented is thus suited for the future mass markets of hydrogen fuel cell technology.S

  1. Evanescent wave DNA-aptamer biosensor based on long period gratings for the specific recognition of E. coli

    NASA Astrophysics Data System (ADS)

    Queirós, R. B.; Gouveia, C.; Fernandes, J. R. A.; Jorge, P. A. S.

    2013-05-01

    An evanescent wave fiber optic sensor for detection of E. coli outer membranes proteins (EcOMPs) is presented. The sensing probe is achieved by the functionalization of a Long Period Grating (LPG) inscribed in a single mode fiber (SMF28) with poly-L-lysine (PLL) resulting in a label-free configuration capable of specific recognition of EcOMPs in waters due to the resonance wavelength shift variation owing to refractive index changes of the medium (≈100 nm/RIU). The sensing head was characterized and tested against EcOMP and applied to spiked environmental water samples. The sensor displayed linear responses in the range of 1×10-10 M to 1×10-8 M EcOMP and is regenerated (under low pH conditions) and the deviation of the subsequent detection was less than 0.1 %.

  2. Mast Cells as Cellular Sensors in Inflammation and Immunity

    PubMed Central

    Beghdadi, Walid; Madjene, Lydia Célia; Benhamou, Marc; Charles, Nicolas; Gautier, Gregory; Launay, Pierre; Blank, Ulrich

    2011-01-01

    Mast cells are localized in tissues. Intense research on these cells over the years has demonstrated their role as effector cells in the maintenance of tissue integrity following injury produced by infectious agents, toxins, metabolic states, etc. After stimulation they release a sophisticated array of inflammatory mediators, cytokines, and growth factors to orchestrate an inflammatory response. These mediators can directly initiate tissue responses on resident cells, but they have also been shown to regulate other infiltrating immune cell functions. Research in recent years has revealed that the outcome of mast cell actions is not always detrimental for the host but can also limit disease development. In addition, mast cell functions highly depend on the physiological context in the organism. Depending on the genetic background, strength of the injurious event, the particular microenvironment, mast cells direct responses ranging from pro- to anti-inflammatory. It appears that they have evolved as cellular sensors to discern their environment in order to initiate an appropriate physiological response either aimed to favor inflammation for repair or at the contrary limit the inflammatory process to prevent further damage. Like every sophisticated machinery, its dysregulation leads to pathology. Given the broad distribution of mast cells in tissues this also explains their implication in many inflammatory diseases. PMID:22566827

  3. A racetrack mode-locked silicon evanescent laser.

    PubMed

    Fang, Alexander W; Koch, Brian R; Gan, Kian-Giap; Park, Hyundai; Jones, Richard; Cohen, Oded; Paniccia, Mario J; Blumenthal, Daniel J; Bowers, John E

    2008-01-21

    By utilizing a racetrack resonator topography, an on-chip mode locked silicon evanescent laser (ML-SEL) is realized that is independent of facet polishing. This enables integration with other devices on silicon and precise control of the ML-SEL's repetition rate through lithographic definition of the cavity length. Both passive and hybrid mode-locking have been achieved with transform limited, 7 ps pulses emitted at a repetition rate of 30 GHz. Jitter and locking range are measured under hybrid mode locking with a minimum absolute jitter and maximum locking range of 364 fs, and 50 MHz, respectively.

  4. Moisture and salt monitoring in concrete by evanescent field dielectrometry

    NASA Astrophysics Data System (ADS)

    Riminesi, C.; Marie-Victoire, E.; Bouichou, M.; Olmi, R.

    2017-01-01

    Monitoring the water content and detecting the presence of soluble salts in concrete is a key issue for its maintenance. Evanescent field dielectrometry, originally developed for the diagnostics of frescoes and mural paintings, is proposed as a tool for monitoring the decay of cement-based materials. A measuring system, based on a scalar network analyzer and a resonant probe, has been realized and tested on concrete samples taken from historical buildings in France or purposely developed in the laboratory. Measurements on water-saturated and oven-dry samples provide the basis for calibrating the instrument for on site monitoring of concrete historical buildings, sculptures and cement-based artifacts.

  5. Evanescent waves and deaf bands in sonic crystals

    NASA Astrophysics Data System (ADS)

    Romero-García, V.; Garcia-Raffi, L. M.; Sánchez-Pérez, J. V.

    2011-12-01

    The properties of sonic crystals (SC) are theoretically investigated in this work by solving the inverse problem k(ω) using the extended plane wave expansion (EPWE). The solution of the resulting eigenvalue problem gives the complex band structure which takes into account both the propagating and the evanescent modes. In this work we show the complete mathematical formulation of the EPWE for SC and the supercell approximation for its use in both a complete SC and a SC with defects. As an example we show a novel interpretation of the deaf bands in a complete SC in good agreement with multiple scattering simulations.

  6. Long-lasting memory from evanescent networks

    PubMed Central

    Routtenberg, Aryeh

    2010-01-01

    Current models of memory typically require a protein synthetic step leading to a more or less permanent structural change in synapses of the network that represent the stored information. This instructive role of protein synthesis has recently been called into question [Routtenberg, A., Rekart, J.L. 2005. Post-translational modification of synaptic proteins as the substrate for long-lasting memory. Trends Neurosci. 28, 12–19]. In its place a new theory is proposed in which post-translational modifications (PTMs) of proteins already synthesized and present within the synapse calibrate synaptic strength. PTM is thus the only mechanism required to sustain long-lasting memories. Activity-induced, PTM-dependent structural modifications within brain synapses then define network formation which is thus a product of the concatenation of cascaded PTMs. This leads to a formulation different from current protein synthesis models in which neural networks initially formed from these individual synaptic PTM-dependent changes is maintained by regulated positive feedback maintains. One such positive feedback mechanism is ‘cryptic rehearsal’ typically referred to as ‘noise’ or ‘spontaneous’ activity. This activity is in fact not random or spontaneous but determined in a stochastic sense by the past history of activation of the nerve cell. To prevent promiscuous network formation, the regulated positive feedback maintains the altered state given specific decay kinetics for the PTM. The up or down state of individual synapses actually exists in an infinite number of intermediate states, never fully ‘up’, nor fully ‘down.’ The networks formed from these uncertain synapses are therefore metastable. A particular memory is also multiply represented by a ‘degenerate code’ so that should loss of a subset of representations occur, erasure can be protected against. This mechanism also solves the flexibility–stability problem by positing that the brain eschews

  7. Evanescent wave absorption measurements of corroded materials using optical fibers as remote probes

    NASA Astrophysics Data System (ADS)

    Namkung, Juock; Hoke, Mike; Schwartz, Andy

    2010-04-01

    This research effort is intended to demonstrate an in-situ optical fiber corrosion sensor that operates in conjunction with a Fourier Transform Infrared (FTIR) interferometer as an evanescent wave absorption spectroscopic technique. This technique will allow periodic remote sensing for onboard structural health monitoring of areas of normally inaccessible structural components. The potential advantages of optical fiber sensors result from the fact that the sensing element, the optical fiber, can be embedded in junctions in aircraft structures, in locations where humidity and corrosion can accumulate, but are such that they can not be directly observed. A fiber-optic-FTIR experimental setup, including several samples of field corrosion material has been assembled in the laboratory to spectrally detect Aluminum Hydroxide [Al(OH)3] which is one component of corrosion of aluminum. Absorption spectra of Al(OH)3, have been collected using an Attenuated Total Reflection (ATR) crystal as a reference spectral signature. The spectra of samples from a simulated corrosion process have been collected and compared with Al(OH)3 spectra. The laboratory experimental setup has included samples from the controlled corrosion conditions.

  8. A self-powered acetaldehyde sensor based on biofuel cell.

    PubMed

    Zhang, Lingling; Zhou, Ming; Dong, Shaojun

    2012-12-04

    Acetaldehyde is recognized as a type of organic environmental pollutant all over the world, which makes the sensitive, rapid, simple and low-cost detection of acetaldehyde urgent and significant. Inspired by the biological principle of feedback modulation, we have developed a novel and effective self-powered device for aqueous acetaldehyde detection. In this self-powered device, an ethanol/air enzymatic biofuel cell (BFC) served as the core component, which showed the maximum power output density of 28.5 μW cm(-2) at 0.34 V and the open circuit potential (V(oc)) of 0.64 V. The product of ethanol oxidation, acetaldehyde, would counteract the electrocatalysis at the bioanode and further decrease the power output of the BFC. Based on such principles, the fabricated acetaldehyde sensor exhibited excellent selectivity with wide linear range (5-200 μM) and low detection limit (1 μM), which conforms to the criteria provided by the World Health Organisation (WHO). In addition, the sensor fabrication is simple, fast, inexpensive, and user-friendly, and the detection process is convenient, efficient, and time-saving, requiring no complicated equipment. These make such self-powered acetaldehyde sensors feasible and practical for detecting aqueous acetaldehyde, particularly in the field of quality control and monitoring aimed at water resource protection.

  9. Cell-tower deployment of counter-sniper sensors

    NASA Astrophysics Data System (ADS)

    Storch, Michael T.

    2004-09-01

    Cellular telephone antenna towers are evaluated as sites for rapid, effective & efficient deployment of counter-sniper sensors, especially in urban environments. They are expected to offer a suitable density, excellent LOS, and a generally limited variety of known or readily-characterized mechanical interfaces. Their precise locations are easily mapped in advance of deployment, are easily accessible by ground and air, and are easily spotted by deployment teams in real-time. We survey issues of EMI & RFI, susceptibility to denial & ambush in military scenarios, and the impact of trends in cell tower design & construction.

  10. Evanescent Field Based Photoacoustics: Optical Property Evaluation at Surfaces

    PubMed Central

    Goldschmidt, Benjamin S.; Rudy, Anna M.; Nowak, Charissa A.; Tsay, Yowting; Whiteside, Paul J. D.; Hunt, Heather K.

    2016-01-01

    Here, we present a protocol to estimate material and surface optical properties using the photoacoustic effect combined with total internal reflection. Optical property evaluation of thin films and the surfaces of bulk materials is an important step in understanding new optical material systems and their applications. The method presented can estimate thickness, refractive index, and use absorptive properties of materials for detection. This metrology system uses evanescent field-based photoacoustics (EFPA), a field of research based upon the interaction of an evanescent field with the photoacoustic effect. This interaction and its resulting family of techniques allow the technique to probe optical properties within a few hundred nanometers of the sample surface. This optical near field allows for the highly accurate estimation of material properties on the same scale as the field itself such as refractive index and film thickness. With the use of EFPA and its sub techniques such as total internal reflection photoacoustic spectroscopy (TIRPAS) and optical tunneling photoacoustic spectroscopy (OTPAS), it is possible to evaluate a material at the nanoscale in a consolidated instrument without the need for many instruments and experiments that may be cost prohibitive. PMID:27500652

  11. Evanescent field shapes excitation profile under axial epi-illumination

    PubMed Central

    2012-01-01

    Abstract. Axial epi-illuminating light transmitting a >1.3-numerical-aperture microscope objective creates an excitation volume at focus with size and shape dictated by diffraction and due to refraction by the objective and by the coverslip interface separating a specimen in aqueous buffer from the oil immersion objective. The evanescent field on the coverslip aqueous side affects primarily the excitation volume axial dimension as the specimen in focus approaches the interface to within a few hundred nanometers. Following excitation, an excited stationary dipole moment emits fluorescence in a spatially varying pattern collected over the large objective aperture. Collected light propagates in parallel rays toward the tube lens that forms a real three-dimensional image that is decoded to identify dipole orientation. An integral representation of the excitation and emitted fields for infinity-corrected optics—including effects of finite conjugate illumination, fluorescence emission near an interface, emitter dipole orientation, spherical aberration, light transmission through a dichroic filter, and for real microscopic specifications—accurately models observed field intensities including the substantial excitation from the evanescent field. The goal is to develop and verify the practical depiction of excitation and emission in a real microscope for quantitative interpretation of the 3-D emission pattern. PMID:22734777

  12. A Feasibility Study on Generation of Acoustic Waves Utilizing Evanescent Light

    NASA Astrophysics Data System (ADS)

    Matsuya, I.; Matozaki, K.; Kosugi, A.; Ihara, I.

    2014-06-01

    A new approach of generating acoustic waves utilizing evanescent light is presented. The evanescent light is a non-propagating electromagnetic wave that exhibits exponential decay with distance from the surface at which the total internal reflection of light is formed. In this research, the evanescent light during total internal reflection at prism surface is utilized for generating acoustic waves in aluminium and the feasibility for ultrasonic measurements is discussed. Pulsed Nd:YAG laser with 0.36 J/cm2 power density is used and the incident angle during the total internal reflection is arranged to be 69.0° for generating the evanescent light. It has been demonstrated that the amplitude of the acoustic waves by means of evanescent light is about 1/14 as large as the one generated by the conventional pulsed laser. This reveals the possibility of using a laser ultrasonic technique with near-field optics.

  13. Effect of sensor systems for cow management on milk production, somatic cell count, and reproduction.

    PubMed

    Steeneveld, W; Vernooij, J C M; Hogeveen, H

    2015-06-01

    To improve management on dairy herds, sensor systems have been developed that can measure physiological, behavioral, and production indicators on individual cows. It is not known whether using sensor systems also improves measures of health and production in dairy herds. The objective of this study was to investigate the effect of using sensor systems on measures of health and production in dairy herds. Data of 414 Dutch dairy farms with (n=152) and without (n=262) sensor systems were available. For these herds, information on milk production per cow, days to first service, first calving age, and somatic cell count (SCC) was provided for the years 2003 to 2013. Moreover, year of investment in sensor systems was available. For every farm year, we determined whether that year was before or after the year of investment in sensor systems on farms with an automatic milking system (AMS) or a conventional milking system (CMS), or whether it was a year on a farm that never invested in sensor systems. Separate statistical analyses were performed to determine the effect of sensor systems for mastitis detection (color, SCC, electrical conductivity, and lactate dehydrogenase sensors), estrus detection for dairy cows, estrus detection for young stock, and other sensor systems (weighing platform, rumination time sensor, fat and protein sensor, temperature sensor, milk temperature sensor, urea sensor, β-hydroxybutyrate sensor, and other sensor systems). The AMS farms had a higher average SCC (by 12,000 cells/mL) after sensor investment, and CMS farms with a mastitis detection system had a lower average SCC (by 10,000 cells/mL) in the years after sensor investment. Having sensor systems was associated with a higher average production per cow on AMS farms, and with a lower average production per cow on CMS farms in the years after investment. The most likely reason for this lower milk production after investment was that on 96% of CMS farms, the sensor system investment occurred

  14. Microfluidic cell culture systems with integrated sensors for drug screening

    NASA Astrophysics Data System (ADS)

    Grist, Samantha; Yu, Linfen; Chrostowski, Lukas; Cheung, Karen C.

    2012-03-01

    Cell-based testing is a key step in drug screening for cancer treatments. A microfluidic platform can permit more precise control of the cell culture microenvironment, such as gradients in soluble factors. These small-scale devices also permit tracking of low cell numbers. As a new screening paradigm, a microscale system for integrated cell culture and drug screening promises to provide a simple, scalable tool to apply standardized protocols used in cellular response assays. With the ability to dynamically control the microenvironment, we can create temporally varying drug profiles to mimic physiologically measured profiles. In addition, low levels of oxygen in cancerous tumors have been linked with drug resistance and decreased likelihood of successful treatment and patient survival. Our work also integrates a thin-film oxygen sensor with a microfluidic oxygen gradient generator which will in future allow us to create spatial oxygen gradients and study effects of hypoxia on cell response to drug treatment. In future, this technology promises to improve cell-based validation in the drug discovery process, decreasing the cost and increasing the speed in screening large numbers of compounds.

  15. Silicon-based microfabricated microbial fuel cell toxicity sensor.

    PubMed

    Dávila, D; Esquivel, J P; Sabaté, N; Mas, J

    2011-01-15

    Microbial fuel cells (MFCs) have been used for several years as biosensors for measuring environmental parameters such as biochemical oxygen demand and water toxicity. The present study is focused on the detection of toxic matter using a novel silicon-based MFC. Like other existing toxicity sensors based on MFCs, this device is capable of detecting the variation on the current produced by the cell when toxic compounds are present in the medium. The MFC approach presented in this work aims to obtain a simple, compact and planar device for its further application as a biosensor in the design and fabrication of equipment for toxicity monitoring. It consists on a proton exchange membrane placed between two microfabricated silicon plates that act as current collectors. An array of square 80 μm × 80 μm vertical channels, 300 μm deep, have been defined trough the plates over an area of 6 mm × 6 mm. The final testing assembly incorporates two perspex pieces positioned onto the plates as reservoirs with a working volume of 144 μL per compartment. The operation of the microdevice as a direct electron transfer MFC has been validated by comparing its performance against a larger scale MFC, run under the same conditions. The device has been tested as a toxicity sensor by setting it at a fixed current while monitoring changes in the output power. A drop in the power production is observed when a toxic compound is added to the anode compartment. The compact design of the device makes it suitable for its incorporation into measurement equipment either as an individual device or as an array of sensors for high throughput processing.

  16. Power optimization in body sensor networks: the case of an autonomous wireless EMG sensor powered by PV-cells.

    PubMed

    Penders, J; Pop, V; Caballero, L; van de Molengraft, J; van Schaijk, R; Vullers, R; Van Hoof, C

    2010-01-01

    Recent advances in ultra-low-power circuits and energy harvesters are making self-powered body sensor nodes a reality. Power optimization at the system and application level is crucial in achieving ultra-low-power consumption for the entire system. This paper reviews system-level power optimization techniques, and illustrates their impact on the case of autonomous wireless EMG monitoring. The resulting prototype, an Autonomous wireless EMG sensor power by PV-cells, is presented.

  17. Bidirectional Promoter Engineering for Single Cell MicroRNA Sensors in Embryonic Stem Cells.

    PubMed

    Sladitschek, Hanna L; Neveu, Pierre A

    2016-01-01

    MicroRNAs have emerged as important markers and regulators of cell identity. Precise measurements of cellular miRNA levels rely traditionally on RNA extraction and thus do not allow to follow miRNA expression dynamics at the level of single cells. Non-invasive miRNA sensors present an ideal solution but they critically depend on the performance of suitable ubiquitous promoters that reliably drive expression both in pluripotent and differentiated cell types. Here we describe the engineering of bidirectional promoters that drive the expression of precise ratiometric fluorescent miRNA sensors in single mouse embryonic stem cells (mESCs) and their differentiated derivatives. These promoters are based on combinations of the widely used CAG, EF1α and PGK promoters as well as the CMV and PGK enhancers. miR-142-3p, which is known to be bimodally expressed in mESCs, served as a model miRNA to gauge the precision of the sensors. The performance of the resulting miRNA sensors was assessed by flow cytometry in single stable transgenic mESCs undergoing self-renewal or differentiation. EF1α promoters arranged back-to-back failed to drive the robustly correlated expression of two transgenes. Back-to-back PGK promoters were shut down during mESC differentiation. However, we found that a back-to-back arrangement of CAG promoters with four CMV enhancers provided both robust expression in mESCs undergoing differentiation and the best signal-to-noise for measurement of miRNA activity in single cells among all the sensors we tested. Such a bidirectional promoter is therefore particularly well suited to study the dynamics of miRNA expression during cell fate transitions at the single cell level.

  18. Controlling the directionality of spontaneous emission by evanescent wave coupling

    SciTech Connect

    Wang, Xue-Lun E-mail: gdhao2@hotmail.com; Hao, Guo-Dong E-mail: gdhao2@hotmail.com; Toda, Naoya

    2015-09-28

    We report an approach toward controlling the directionality of spontaneous emissions by employing the evanescent wave coupling effect in a subwavelength-sized ridge or truncated cone structure. An InGaAs/GaAs light-emitting diode in which a stripe-shaped InGaAs/GaAs quantum well with a stripe width of about 100 nm is embedded at the center of a subwavelength-sized GaAs ridge (of width ∼520 nm) is fabricated by micro processing and epitaxial regrowth techniques. Strong directionalities characterized by a half-intensity angle of 43° are observed in planes perpendicular to the ridge axis. The directionality is found to be almost independent of operating conditions.

  19. Design and application of fiber optic evanescent wave biosensor

    NASA Astrophysics Data System (ADS)

    Huang, Huijie; Zhai, Junhui; Zhao, Yongkai; Yang, Ruifu; Ren, Bingqiang; Cheng, Zhaogu; Du, Longlong; Lu, Dunwu

    2003-12-01

    A fiber-optic biosensor is developed based on the principle of evanescent wave while light propagates in optical fiber. The biosensor uses a red laser diode at 636.85 nm for exciting Cy5 fluorescent dye. Sensitivity limit of 0.01 nnmol/l is obtained from the detection of serial Cy5 solutions with various concentrations. In log-to-log plot, excellent linear response characteristic is seen in the Cy5 concentrations ranging from 0.01 nmlo/l to 100 nmol/l. And a good result of signal-to-noise ratio of 4.61 is obtained when the biosensor is used to measure Legionella pneumophila solution of 0.01 μmol/l. All the results are comparable with those that are obtained by a commercial biochip scanner GeneTAC 1000.

  20. Interplay between evanescence and disorder in deep subwavelength photonic structures

    NASA Astrophysics Data System (ADS)

    Herzig Sheinfux, Hanan; Kaminer, Ido; Genack, Azriel Z.; Segev, Mordechai

    2016-10-01

    Deep subwavelength features are expected to have minimal impact on wave transport. Here we show that in contrast to this common understanding, disorder can have a dramatic effect in a one-dimensional disordered optical system with spatial features a thousand times smaller than the wavelength. We examine a unique regime of Anderson localization where the localization length is shown to scale linearly with the wavelength instead of diverging, because of the role of evanescent waves. In addition, we demonstrate an unusual order of magnitude enhancement of transmission induced due to localization. These results are described for electromagnetic waves, but are directly relevant to other wave systems such as electrons in multi-quantum-well structures.

  1. Interplay between evanescence and disorder in deep subwavelength photonic structures

    PubMed Central

    Herzig Sheinfux, Hanan; Kaminer, Ido; Genack, Azriel Z.; Segev, Mordechai

    2016-01-01

    Deep subwavelength features are expected to have minimal impact on wave transport. Here we show that in contrast to this common understanding, disorder can have a dramatic effect in a one-dimensional disordered optical system with spatial features a thousand times smaller than the wavelength. We examine a unique regime of Anderson localization where the localization length is shown to scale linearly with the wavelength instead of diverging, because of the role of evanescent waves. In addition, we demonstrate an unusual order of magnitude enhancement of transmission induced due to localization. These results are described for electromagnetic waves, but are directly relevant to other wave systems such as electrons in multi-quantum-well structures. PMID:27708260

  2. Cell-based capacitance sensor for analysis of EGFR expression on cell membrane

    NASA Astrophysics Data System (ADS)

    Shin, Dong-Myeong; Shin, Yong-Cheol; Ha, Ji Hye; Lee, Jong-Ho; Han, Dong-Wook; Kim, Jong-Man; Kim, Hyung Kook; Hwang, Yoon-Hwae

    2013-02-01

    Cancer cells have many kinds of cancer biomarkers. Among them, the epidermal growth factor (EGF) receptors can show a possibility for a cancer marker because the over-expression of EGF receptor is related with fibrous, colorectal, cervical and gastric tumorigenesis. We fabricated the capacitance sensor with a gap area of 50 μm × 200 μm by using photolithography and lift-off method. Using the capacitance sensor, we investigated the time dependent capacitance changes of different kinds of fibrous cells, such as HT1080 fibrosarcoma, L-929 fibroblast cell line and nHDF dermal fibroblast primary cell. We found that when we put the EGF, the capacitance decreased due to the immobilization of EGF to EGF receptor on the cell membrane. The quantitative determination of EGF receptor level for various fibrous cells was carried out and the results showed good correlation with conventional method. Based on our results, we suggest that the capacitance sensor can measure the expression level of the EGF receptor on cell membrane and be a good candidate as a cancer diagnosis.

  3. Size sensors in bacteria, cell cycle control, and size control.

    PubMed

    Robert, Lydia

    2015-01-01

    Bacteria proliferate by repetitive cycles of cellular growth and division. The progression into the cell cycle is admitted to be under the control of cell size. However, the molecular basis of this regulation is still unclear. Here I will discuss which mechanisms could allow coupling growth and division by sensing size and transmitting this information to the division machinery. Size sensors could act at different stages of the cell cycle. During septum formation, mechanisms controlling the formation of the Z ring, such as MinCD inhibition or Nucleoid Occlusion (NO) could participate in the size-dependence of the division process. In addition or alternatively, the coupling of growth and division may occur indirectly through the control of DNA replication initiation. The relative importance of these different size-sensing mechanisms could depend on the environmental and genetic context. The recent demonstration of an incremental strategy of size control in bacteria, suggests that DnaA-dependent control of replication initiation could be the major size control mechanism limiting cell size variation.

  4. Size sensors in bacteria, cell cycle control, and size control

    PubMed Central

    Robert, Lydia

    2015-01-01

    Bacteria proliferate by repetitive cycles of cellular growth and division. The progression into the cell cycle is admitted to be under the control of cell size. However, the molecular basis of this regulation is still unclear. Here I will discuss which mechanisms could allow coupling growth and division by sensing size and transmitting this information to the division machinery. Size sensors could act at different stages of the cell cycle. During septum formation, mechanisms controlling the formation of the Z ring, such as MinCD inhibition or Nucleoid Occlusion (NO) could participate in the size-dependence of the division process. In addition or alternatively, the coupling of growth and division may occur indirectly through the control of DNA replication initiation. The relative importance of these different size-sensing mechanisms could depend on the environmental and genetic context. The recent demonstration of an incremental strategy of size control in bacteria, suggests that DnaA-dependent control of replication initiation could be the major size control mechanism limiting cell size variation. PMID:26074903

  5. Cellulose antibody films for highly specific evanescent wave immunosensors

    NASA Astrophysics Data System (ADS)

    Hartmann, Andreas; Bock, Daniel; Jaworek, Thomas; Kaul, Sepp; Schulze, Matthais; Tebbe, H.; Wegner, Gerhard; Seeger, Stefan

    1996-01-01

    For the production of recognition elements for evanescent wave immunosensors optical waveguides have to be coated with ultrathin stable antibody films. In the present work non amphiphilic alkylated cellulose and copolyglutamate films are tested as monolayer matrices for the antibody immobilization using the Langmuir-Blodgett technique. These films are transferred onto optical waveguides and serve as excellent matrices for the immobilization of antibodies in high density and specificity. In addition to the multi-step immobilization of immunoglobulin G(IgG) on photochemically crosslinked and oxidized polymer films, the direct one-step transfer of mixed antibody-polymer films is performed. Both planar waveguides and optical fibers are suitable substrates for the immobilization. The activity and specificity of immobilized antibodies is controlled by the enzyme-linked immunosorbent assay (ELISA) technique. As a result reduced non-specific interactions between antigens and the substrate surface are observed if cinnamoylbutyether-cellulose is used as the film matrix for the antibody immobilization. Using the evanescent wave senor (EWS) technology immunosensor assays are performed in order to determine both the non-specific adsorption of different coated polymethylmethacrylat (PMMA) fibers and the long-term stability of the antibody films. Specificities of one-step transferred IgG-cellulose films are drastically enhanced compared to IgG-copolyglutamate films. Cellulose IgG films are used in enzymatic sandwich assays using mucine as a clinical relevant antigen that is recognized by the antibodies BM2 and BM7. A mucine calibration measurement is recorded. So far the observed detection limit for mucine is about 8 ng/ml.

  6. Optical fiber sensing of corroded materials with evanescent wave absorption measurements

    NASA Astrophysics Data System (ADS)

    Namkung, Juock; Schwartz, Andy

    2012-06-01

    This research effort is to demonstrate a remote sensing method using optical fibers with a Fourier Transform Infrared (FTIR) interferometer as an evanescent wave spectroscopic technique. In addition to the usual advantages of optical fiber sensors, such as small size and weight, optical fibers can be embedded in aircraft structures in locations where humidity and corrosion can accumulate but cannot be directly observed. A fiber-optic-FTIR experimental setup, including several samples of field corroded materials, has been assembled to spectrally detect Aluminum Hydroxide [Al(OH)3] which is one of the major components of aluminum corrosion. Absorption spectra of Al(OH)3 have been collected using an Attenuated Total Reflection (ATR) crystal as a reference spectral signature. The absorption spectra of samples from a simulated corrosion process and from the field corroded structures have been collected and compared with the reference Al(OH)3 spectra. Chalcogenide optical fibers are used for remote sensing purposes to detect corrosion. Two distinctive absorption peaks, attributable to aluminum hydroxide, are noticed from the simulated corrosion and from the field corroded structures.

  7. Portable evanescent wave fiber biosensor for highly sensitive detection of Shigella

    NASA Astrophysics Data System (ADS)

    Xiao, Rui; Rong, Zhen; Long, Feng; Liu, Qiqi

    2014-11-01

    A portable evanescent wave fiber biosensor was developed to achieve the rapid and highly sensitive detection of Shigella. In this study, a DNA probe was covalently immobilized onto fiber-optic biosensors that can hybridize with a fluorescently labeled complementary DNA. The sensitivity of detection for synthesized oligonucleotides can reach 10-10 M. The surface of the sensor can be regenerated with 0.5% sodium dodecyl sulfate solution (pH 1.9) for over 30 times without significant deterioration of performance. The total analysis time for a single sample, including the time for measurement and surface regeneration, was less than 6 min. We employed real-time polymerase chain reaction (PCR) and compared the results of both methods to investigate the actual Shigella DNA detection capability of the fiber-optic biosensor. The fiber-optic biosensor could detect as low as 102 colony-forming unit/mL Shigella. This finding was comparable with that by real-time PCR, which suggests that this method is a potential alternative to existing detection methods.

  8. Infrared fiber optic evanescent wave spectroscopy for the study of diffusion in the human skin

    NASA Astrophysics Data System (ADS)

    Raichlin, Yosef; Goldberg, I.; Brenner, Sarah; Shulzinger, Evgeny; Katzir, Abraham

    2002-03-01

    Fourier Transform Infrared (FTIR) spectroscopic systems make use of Attenuated Total Reflection (ATR) elements for the study of skin in dermatology. FTIR - ATR allows real time and reagent-less analysis of several components, simultaneously. The potential for skin studies is increased by the development of the flexible fiber optic sensor made from infrared transparent polycrystalline silver halide. Segments of fibers can replace the ATR sensing elements inside an FTIR system. Moreover a Fiberoptic Evanescent Wave Spectroscopy (FEWS) can also be used for real time in vivo measurement on skin, in situ. We used FEWS to study the diffusion of UV sunscreen lotions from the outer skin layer into the dermis and epidermis, and used the various absorption bands to differentiate between the behavior of the organic and the water molecules in the lotion. FEWS can be a powerful tool for studying the transport of drugs and cosmetic creams through the skin from the stratum corneum to the dermis and epidermis and for studying the lateral diffusion of various molecules into the skin, in vivo and in real time.

  9. Development of sensors and sensing technology for hydrogen fuel cell vehicle applications

    SciTech Connect

    Brosha, Eric L; Sekhar, Praveen K; Mukundan, Rangchary; Williamson, Todd L; Barzon, Fernando H; Woo, Leta Y; Glass, Robert S

    2010-01-01

    One related area of hydrogen fuel cell vehicle (FCV) development that cannot be overlooked is the anticipated requirement for new sensors for both the monitoring and control of the fuel cell's systems and for those devices that will be required for safety. Present day automobiles have dozens of sensors on-board including those for IC engine management/control, sensors for state-of-health monitoring/control of emissions systems, sensors for control of active safety systems, sensors for triggering passive safety systems, and sensors for more mundane tasks such as fluids level monitoring to name the more obvious. The number of sensors continues to grow every few years as a result of safety mandates but also in response to consumer demands for new conveniences and safety features.

  10. Study on phase-locked coherence of evanescent wave coupling in solid-state laser

    NASA Astrophysics Data System (ADS)

    Chen, Yong; Liu, Xu; Zhu, Mengzhen; Lu, Changyong; Lu, Yimin; Tan, Caoyong; Wei, Shangfang

    2016-01-01

    The mechanism and characteristics of evanescent-wave coupling in solid-state laser is analyzed theoretically and experimentally. The results shown that self-organized phase locking between laser modes can be realized by evanescentwave coupling in solid-state laser. Based on "mutual injection and evanescent wave" characteristics of corner-cube prism, the paper reveals that far-field output of corner-cube laser is the inner reason and mechanism of coherent combining distribution by theory of evanescent wave and its coherence is better than plane parallel resonator. And "mutually coupled phase locking of six lasers based cube-corner resonator" scheme is proposed on this basis.

  11. U-shaped, double-tapered, fiber-optic sensor for effective biofilm growth monitoring

    PubMed Central

    Zhong, Nianbing; Zhao, Mingfu; Li, Yishan

    2016-01-01

    To monitor biofilm growth on polydimethylsiloxane in a photobioreactor effectively, the biofilm cells and liquids were separated and measured using a sensor with two U-shaped, double-tapered, fiber-optic probes (Sen. and Ref. probes). The probes’ Au-coated hemispherical tips enabled double-pass evanescent field absorption. The Sen. probe sensed the cells and liquids inside the biofilm. The polyimide–silica hybrid-film-coated Ref. probe separated the liquids from the biofilm cells and analyzed the liquid concentration. The biofilm structure and active biomass were also examined to confirm the effectiveness of the measurement using a simulation model. The sensor was found to effectively respond to the biofilm growth in the adsorption through exponential phases at thicknesses of 0–536 μm. PMID:26977344

  12. White blood cell counting on smartphone paper electrochemical sensor.

    PubMed

    Wang, Xinhao; Lin, Guohong; Cui, Guangzhe; Zhou, Xiangfei; Liu, Gang Logan

    2017-04-15

    White blood cell (WBC) analysis provides rich information in rapid diagnosis of acute bacterial and viral infections as well as chronic disease management. For patients with immune deficiency or leukemia WBC should be persistently monitored. Current WBC counting method relies on bulky instrument and trained personnel and is time consuming. Rapid, low-cost and portable solution is in highly demand for point of care test. Here we demonstrate a label-free smartphone based electrochemical WBC counting device on microporous paper with patterned gold microelectrodes. WBC separated from whole blood was trapped by the paper with microelectrodes. WBC trapped on the paper leads to the ion diffusion blockage on microelectrodes, therefore cell concentration is determined by peak current on the microelectrodes measured by a differential pulse voltammeter and the quantitative results are collected by a smartphone wirelessly within 1min. We are able to rapidly quantify WBC concentrations covering the common physiological and pathological range (200-20000μL(-1)) with only 10μL sample and high repeatability as low as 10% in CoV (Coefficient of Variation). The unique smartphone paper electrochemical sensor ensures fast cell quantification to achieve rapid and low-cost WBC analysis at the point-of-care under resource limited conditions.

  13. Cell-bionics: tools for real-time sensor processing.

    PubMed

    Toumazou, Chris; Cass, Tony

    2007-08-29

    The accurate monitoring of the physiological status of cells, tissues and whole organisms demands a new generation of devices capable of providing accurate data in real time with minimal perturbation of the system being measured. To deliver on the promise of cell-bionics advances over the past decade in miniaturization, analogue signal processing, low-power electronics, materials science and protein engineering need to be brought together. In this paper we summarize recent advances in our research that is moving us in this direction. Two areas in particular are highlighted: the exploitation of the physical properties inherent in semiconductor devices to perform very low power on chip signal processing and the use of gene technology to tailor proteins for sensor applications. In the context of engineered tissues, cell-bionics could offer the ability to monitor the precise physiological state of the construct, both during 'manufacture' and post-implantation. Monitoring during manufacture, particularly by embedded devices, would offer quality assurance of the materials components and the fabrication process. Post-implantation monitoring would reveal changes in the underlying physiology as a result of the tissue construct adapting to its new environment.

  14. An experimental investigation of energy transmission from an evanescent to a propagating region

    NASA Astrophysics Data System (ADS)

    Lee, Allison; Crockett, Julie

    2016-11-01

    Tidal flow over oceanic bathymetry is a well known generator of internal waves. However, in the deep ocean there are many regions of weak stratification and the tides will generate only evanescent waves which decay exponentially as they propagate away from their source. In locations where stronger stratification exists above the weak, evanescent waves can form propagating internal waves as they approach a depth with a stratification corresponding to their frequency (turning depth). An experimental study of the energy transfer from evanescent regions to propagating regions due to evanescent waves passing through a turning depth is presented. The effects of varying exponential stratification profiles and single and multi-peak topographical features are described and results are compared with linear theory approximations.

  15. Optical fiber sensor for allergen detection

    NASA Astrophysics Data System (ADS)

    Bendoula, R.; Wacogne, B.; Giust, R.; Cherioux, F.; Sandoz, P.; Gharbi, T.

    2005-08-01

    The sensor is dedicated to the detection of allergens. We use a biochemical reaction in the vicinity of the core of an optical fiber which modifies the propagation conditions of the optical wave by evanescent coupling. The detection involves a intrinsic optical fiber Fabry-Perot interferometer.

  16. Current-Induced Transistor Sensorics with Electrogenic Cells.

    PubMed

    Fromherz, Peter

    2016-04-25

    The concepts of transistor recording of electroactive cells are considered, when the response is determined by a current-induced voltage in the electrolyte due to cellular activity. The relationship to traditional transistor recording, with an interface-induced response due to interactions with the open gate oxide, is addressed. For the geometry of a cell-substrate junction, the theory of a planar core-coat conductor is described with a one-compartment approximation. The fast electrical relaxation of the junction and the slow change of ion concentrations are pointed out. On that basis, various recording situations are considered and documented by experiments. For voltage-gated ion channels under voltage clamp, the effects of a changing extracellular ion concentration and the enhancement/depletion of ion conductances in the adherent membrane are addressed. Inhomogeneous ion conductances are crucial for transistor recording of neuronal action potentials. For a propagating action potential, the effects of an axon-substrate junction and the surrounding volume conductor are distinguished. Finally, a receptor-transistor-sensor is described, where the inhomogeneity of a ligand-activated ion conductance is achieved by diffusion of the agonist and inactivation of the conductance. Problems with regard to a development of reliable biosensors are mentioned.

  17. Current-Induced Transistor Sensorics with Electrogenic Cells

    PubMed Central

    Fromherz, Peter

    2016-01-01

    The concepts of transistor recording of electroactive cells are considered, when the response is determined by a current-induced voltage in the electrolyte due to cellular activity. The relationship to traditional transistor recording, with an interface-induced response due to interactions with the open gate oxide, is addressed. For the geometry of a cell-substrate junction, the theory of a planar core-coat conductor is described with a one-compartment approximation. The fast electrical relaxation of the junction and the slow change of ion concentrations are pointed out. On that basis, various recording situations are considered and documented by experiments. For voltage-gated ion channels under voltage clamp, the effects of a changing extracellular ion concentration and the enhancement/depletion of ion conductances in the adherent membrane are addressed. Inhomogeneous ion conductances are crucial for transistor recording of neuronal action potentials. For a propagating action potential, the effects of an axon-substrate junction and the surrounding volume conductor are distinguished. Finally, a receptor-transistor-sensor is described, where the inhomogeneity of a ligand–activated ion conductance is achieved by diffusion of the agonist and inactivation of the conductance. Problems with regard to a development of reliable biosensors are mentioned. PMID:27120627

  18. Evanescent field in surface plasmon resonance and surface plasmon field-enhanced fluorescence spectroscopies.

    PubMed

    Ekgasit, Sanong; Thammacharoen, Chuchaat; Yu, Fang; Knoll, Wolfgang

    2004-04-15

    The highly sensitive nature of surface plasmon resonance (SPR) spectroscopy and surface plasmon field-enhanced fluorescence spectroscopy (SPFS) are governed by the strong surface plasmon resonance-generated evanescent field at the metal/dielectric interface. The greatest evanescent field amplitude at the interface and the maximum attenuation of the reflectance are observed when a nonabsorbing dielectric is employed. An absorbing dielectric decreases the evanescent field enhancement at the interface. The SPR curve of an absorbing dielectric is characterized by a greater reflectance minimum and a broader curve, as compared to those of the nonabsorbing dielectric with the same refractive index. For a weakly absorbing dielectric, such as nanometer-thick surface-confined fluorophores, the absorption is too small to induce a significant change in the SPR curve. However, the presence of a minute amount of the fluorophore can be detected by the highly sensitive SPFS. The angle with the maximum fluorescence intensity of an SPFS curve is always smaller than the resonance angle of the corresponding SPR curve. This discrepancy is due to the differences of evanescent field distributions and their decay characteristics within the metal film and the dielectric medium. The fluorescence intensity in an SPFS curve can be expressed in terms of the evanescent field amplitude. Excellent correlations between the experimentally measured fluorescence intensities and the evanescent field amplitudes are observed.

  19. Magnetic Relaxometry with an Atomic Magnetometer and SQUID Sensors on Targeted Cancer Cells

    PubMed Central

    Johnson, Cort; Adolphi, Natalie L.; Butler, Kimberly L.; Debbie M, Lovato; Larson, Richard; Schwindt, Peter D.D.; Flynn, Edward R.

    2012-01-01

    Magnetic relaxometry methods have been shown to be very sensitive in detecting cancer cells and other targeted diseases. Superconducting Quantum Interference Device (SQUID) sensors are one of the primary sensor systems used in this methodology because of their high sensitivity with demonstrated capabilities of detecting fewer than 100,000 magnetically-labeled cancer cells. The emerging technology of atomic magnetometers (AM) represents a new detection method for magnetic relaxometry with high sensitivity and without the requirement for cryogens. We report here on a study of magnetic relaxometry using both AM and SQUID sensors to detect cancer cells that are coated with superparamagnetic nanoparticles through antibody targeting. The AM studies conform closely to SQUID sensor results in the measurement of the magnetic decay characteristics following a magnetization pulse. The AM and SQUID sensor data are well described theoretically for superparamagnetic particles bound to cells and the results can be used to determine the number of cells in a cell culture or tumor. The observed fields and magnetic moments of cancer cells are linear with the number of cells over a very large range. The AM sensor demonstrates very high sensitivity for detecting magnetically labeled cells does not require cryogenic cooling and is relatively inexpensive. PMID:22773885

  20. Evanescent field: A potential light-tool for theranostics application

    NASA Astrophysics Data System (ADS)

    Polley, Nabarun; Singh, Soumendra; Giri, Anupam; Pal, Samir Kumar

    2014-03-01

    A noninvasive or minimally invasive optical approach for theranostics, which would reinforce diagnosis, treatment, and preferably guidance simultaneously, is considered to be major challenge in biomedical instrument design. In the present work, we have developed an evanescent field-based fiber optic strategy for the potential theranostics application in hyperbilirubinemia, an increased concentration of bilirubin in the blood and is a potential cause of permanent brain damage or even death in newborn babies. Potential problem of bilirubin deposition on the hydroxylated fiber surface at physiological pH (7.4), that masks the sensing efficacy and extraction of information of the pigment level, has also been addressed. Removal of bilirubin in a blood-phantom (hemoglobin and human serum albumin) solution from an enhanced level of 77 μM/l (human jaundice >50 μM/l) to ˜30 μM/l (normal level ˜25 μM/l in human) using our strategy has been successfully demonstrated. In a model experiment using chromatography paper as a mimic of biological membrane, we have shown efficient degradation of the bilirubin under continuous monitoring for guidance of immediate/future course of action.

  1. High-content analysis of single cells directly assembled on CMOS sensor based on color imaging.

    PubMed

    Tanaka, Tsuyoshi; Saeki, Tatsuya; Sunaga, Yoshihiko; Matsunaga, Tadashi

    2010-12-15

    A complementary metal oxide semiconductor (CMOS) image sensor was applied to high-content analysis of single cells which were assembled closely or directly onto the CMOS sensor surface. The direct assembling of cell groups on CMOS sensor surface allows large-field (6.66 mm×5.32 mm in entire active area of CMOS sensor) imaging within a second. Trypan blue-stained and non-stained cells in the same field area on the CMOS sensor were successfully distinguished as white- and blue-colored images under white LED light irradiation. Furthermore, the chemiluminescent signals of each cell were successfully visualized as blue-colored images on CMOS sensor only when HeLa cells were placed directly on the micro-lens array of the CMOS sensor. Our proposed approach will be a promising technique for real-time and high-content analysis of single cells in a large-field area based on color imaging.

  2. A cell-surface-anchored ratiometric i-motif sensor for extracellular pH detection.

    PubMed

    Ying, Le; Xie, Nuli; Yang, Yanjing; Yang, Xiaohai; Zhou, Qifeng; Yin, Bincheng; Huang, Jin; Wang, Kemin

    2016-06-14

    A FRET-based sensor is anchored on the cell surface through streptavidin-biotin interactions. Due to the excellent properties of the pH-sensitive i-motif structure, the sensor can detect extracellular pH with high sensitivity and excellent reversibility.

  3. Passive Dew Droplet Removal from Hydrogen Sensors for Fuel Cell Applications

    NASA Astrophysics Data System (ADS)

    Kano, Masataka; Ishii, Makoto; Yoshinaga, Haruo; Esashi, Masayoshi; Tanaka, Shuji

    This paper describes three structures to passively remove condensed water droplets from a gas heat conduction type hydrogen sensor for fuel cell applications. The three structures are A: water-repellent coating surrounded by water-absorbing porous ceramic coating, B: suspended porous membrane over a water-repellent sensor surface and C: wettability gradient for water droplet elimination. A real hydrogen sensor was used as a platform for the water-droplet-removal structures. Using helium instead of hydrogen, A and B type sensors and a reference sensor without water-droplet-removal structures were tested in a wet and hot atmosphere simulating a fuel cell environment. B type sensor showed normal output even after exposure to a dew-condensing atmosphere, while the reference and A type sensors showed abnormal output, suggesting dew condensation on the sensor surfaces. For C type sensor, a photochromic compound film on a super-water-repellent undercoat, which changes its wettability by ultraviolet exposure, was used. It was confirmed that the wettability could be controlled by ultraviolet exposure from 157.9° to 72.8° in water contact angle.

  4. Characterization of the evanescent field profile and bound mass sensitivity of a label-free silicon photonic microring resonator biosensing platform.

    PubMed

    Luchansky, Matthew S; Washburn, Adam L; Martin, Teresa A; Iqbal, Muzammil; Gunn, L Cary; Bailey, Ryan C

    2010-12-15

    Silicon photonic microring resonators have emerged as a sensitive and highly multiplexed platform for real-time biomolecule detection. Herein, we profile the evanescent decay of device sensitivity towards molecular binding as a function of distance from the microring surface. By growing multilayers of electrostatically bound polymers extending from the sensor surface, we are able to empirically determine that the evanescent field intensity is characterized by a 1/e response decay distance of 63 nm. We then applied this knowledge to study the growth of biomolecular assemblies consisting of alternating layers of biotinylated antibody and streptavidin, which follow a more complex growth pattern. Additionally, by monitoring the shift in microring resonance wavelength upon the deposition of a radioactively labeled protein, the mass sensitivity of the ring resonator platform was determined to be 14.7±6.7 [pg/mm(2)]/Δpm. By extrapolating to the instrument noise baseline, the mass/area limit of detection is found to be 1.5±0.7 pg/mm(2). Taking the small surface area of the microring sensor into consideration, this value corresponds to an absolute mass detection limit of 125 ag (i.e. 0.8 zmol of IgG), demonstrating the remarkable sensitivity of this promising label-free biomolecular sensing platform.

  5. Stretchable Electrochemical Sensor for Real-Time Monitoring of Cells and Tissues.

    PubMed

    Liu, Yan-Ling; Jin, Zi-He; Liu, Yan-Hong; Hu, Xue-Bo; Qin, Yu; Xu, Jia-Quan; Fan, Cui-Fang; Huang, Wei-Hua

    2016-03-24

    Stretchable electrochemical sensors are conceivably a powerful technique that provides important chemical information to unravel elastic and curvilinear living body. However, no breakthrough was made in stretchable electrochemical device for biological detection. Herein, we synthesized Au nanotubes (NTs) with large aspect ratio to construct an effective stretchable electrochemical sensor. Interlacing network of Au NTs endows the sensor with desirable stability against mechanical deformation, and Au nanostructure provides excellent electrochemical performance and biocompatibility. This allows for the first time, real-time electrochemical monitoring of mechanically sensitive cells on the sensor both in their stretching-free and stretching states as well as sensing of the inner lining of blood vessels. The results demonstrate the great potential of this sensor in electrochemical detection of living body, opening a new window for stretchable electrochemical sensor in biological exploration.

  6. Highly sensitive and selective odorant sensor using living cells expressing insect olfactory receptors

    PubMed Central

    Misawa, Nobuo; Mitsuno, Hidefumi; Kanzaki, Ryohei; Takeuchi, Shoji

    2010-01-01

    This paper describes a highly sensitive and selective chemical sensor using living cells (Xenopus laevis oocytes) within a portable fluidic device. We constructed an odorant sensor whose sensitivity is a few parts per billion in solution and can simultaneously distinguish different types of chemicals that have only a slight difference in double bond isomerism or functional group such as ─OH, ─CHO and ─C(═O)─. We developed a semiautomatic method to install cells to the fluidic device and achieved stable and reproducible odorant sensing. In addition, we found that the sensor worked for multiple-target chemicals and can be integrated with a robotic system without any noise reduction systems. Our developed sensor is compact and easy to replace in the system. We believe that the sensor can potentially be incorporated into a portable system for monitoring environmental and physical conditions. PMID:20798064

  7. Online soft sensor of humidity in PEM fuel cell based on dynamic partial least squares.

    PubMed

    Long, Rong; Chen, Qihong; Zhang, Liyan; Ma, Longhua; Quan, Shuhai

    2013-01-01

    Online monitoring humidity in the proton exchange membrane (PEM) fuel cell is an important issue in maintaining proper membrane humidity. The cost and size of existing sensors for monitoring humidity are prohibitive for online measurements. Online prediction of humidity using readily available measured data would be beneficial to water management. In this paper, a novel soft sensor method based on dynamic partial least squares (DPLS) regression is proposed and applied to humidity prediction in PEM fuel cell. In order to obtain data of humidity and test the feasibility of the proposed DPLS-based soft sensor a hardware-in-the-loop (HIL) test system is constructed. The time lag of the DPLS-based soft sensor is selected as 30 by comparing the root-mean-square error in different time lag. The performance of the proposed DPLS-based soft sensor is demonstrated by experimental results.

  8. Online Soft Sensor of Humidity in PEM Fuel Cell Based on Dynamic Partial Least Squares

    PubMed Central

    Long, Rong; Chen, Qihong; Zhang, Liyan; Ma, Longhua; Quan, Shuhai

    2013-01-01

    Online monitoring humidity in the proton exchange membrane (PEM) fuel cell is an important issue in maintaining proper membrane humidity. The cost and size of existing sensors for monitoring humidity are prohibitive for online measurements. Online prediction of humidity using readily available measured data would be beneficial to water management. In this paper, a novel soft sensor method based on dynamic partial least squares (DPLS) regression is proposed and applied to humidity prediction in PEM fuel cell. In order to obtain data of humidity and test the feasibility of the proposed DPLS-based soft sensor a hardware-in-the-loop (HIL) test system is constructed. The time lag of the DPLS-based soft sensor is selected as 30 by comparing the root-mean-square error in different time lag. The performance of the proposed DPLS-based soft sensor is demonstrated by experimental results. PMID:24453923

  9. Evaluation of a Multi-Parameter Sensor for Automated, Continuous Cell Culture Monitoring in Bioreactors

    NASA Technical Reports Server (NTRS)

    Pappas, D.; Jeevarajan, A.; Anderson, M. M.

    2004-01-01

    Compact and automated sensors are desired for assessing the health of cell cultures in biotechnology experiments in microgravity. Measurement of cell culture medium allows for the optirn.jzation of culture conditions on orbit to maximize cell growth and minimize unnecessary exchange of medium. While several discrete sensors exist to measure culture health, a multi-parameter sensor would simplify the experimental apparatus. One such sensor, the Paratrend 7, consists of three optical fibers for measuring pH, dissolved oxygen (p02), dissolved carbon dioxide (pC02) , and a thermocouple to measure temperature. The sensor bundle was designed for intra-arterial placement in clinical patients, and potentially can be used in NASA's Space Shuttle and International Space Station biotechnology program bioreactors. Methods: A Paratrend 7 sensor was placed at the outlet of a rotating-wall perfused vessel bioreactor system inoculated with BHK-21 (baby hamster kidney) cells. Cell culture medium (GTSF-2, composed of 40% minimum essential medium, 60% L-15 Leibovitz medium) was manually measured using a bench top blood gas analyzer (BGA, Ciba-Corning). Results: A Paratrend 7 sensor was used over a long-term (>120 day) cell culture experiment. The sensor was able to track changes in cell medium pH, p02, and pC02 due to the consumption of nutrients by the BHK-21. When compared to manually obtained BGA measurements, the sensor had good agreement for pH, p02, and pC02 with bias [and precision] of 0.02 [0.15], 1 mm Hg [18 mm Hg], and -4.0 mm Hg [8.0 mm Hg] respectively. The Paratrend oxygen sensor was recalibrated (offset) periodically due to drift. The bias for the raw (no offset or recalibration) oxygen measurements was 42 mm Hg [38 mm Hg]. The measured response (rise) time of the sensor was 20 +/- 4s for pH, 81 +/- 53s for pC02, 51 +/- 20s for p02. For long-term cell culture measurements, these response times are more than adequate. Based on these findings , the Paratrend sensor could

  10. Detection of cells captured with antigens on shear horizontal surface-acoustic-wave sensors.

    PubMed

    Hao, Hsu-Chao; Chang, Hwan-You; Wang, Tsung-Pao; Yao, Da-Jeng

    2013-02-01

    Techniques to separate cells are widely applied in immunology. The technique to separate a specific antigen on a microfluidic platform involves the use of a shear horizontal surface-acoustic-wave (SH-SAW) sensor. With specific antibodies conjugated onto the surface of the SH-SAW sensors, this technique can serve to identify specific cells in bodily fluids. Jurkat cells, used as a target in this work, provide a model of cells in small abundance (1:1000) for isolation and purification with the ultimate goal of targeting even more dilute cells. T cells were separated from a mixed-cell medium on a chip (Jurkat cells/K562 cells, 1/1000). A novel microchamber was developed to capture cells during the purification, which required a large biosample. Cell detection was demonstrated through the performance of genetic identification on the chip.

  11. Development of Sensors and Sensing Technology for Hydrogen Fuel Cell Vehicle Applications

    SciTech Connect

    Brosha, E L; Sekhar, P K; Mukundan, R; Williamson, T; Garzon, F H; Woo, L Y; Glass, R R

    2010-01-06

    One related area of hydrogen fuel cell vehicle (FCV) development that cannot be overlooked is the anticipated requirement for new sensors for both the monitoring and control of the fuel cell's systems and for those devices that will be required for safety. Present day automobiles have dozens of sensors on-board including those for IC engine management/control, sensors for state-of-health monitoring/control of emissions systems, sensors for control of active safety systems, sensors for triggering passive safety systems, and sensors for more mundane tasks such as fluids level monitoring to name the more obvious. The number of sensors continues to grow every few years as a result of safety mandates but also in response to consumer demands for new conveniences and safety features. Some of these devices (e.g. yaw sensors for dynamic stability control systems or tire presure warning RF-based devices) may be used on fuel cell vehicles without any modification. However the use of hydrogen as a fuel will dictate the development of completely new technologies for such requirements as the detection of hydrogen leaks, sensors and systems to continuously monitor hydrogen fuel purity and protect the fuel cell stack from poisoning, and for the important, yet often taken for granted, tasks such as determining the state of charge of the hydrogen fuel storage and delivery system. Two such sensors that rely on different transduction mechanisms will be highlighted in this presentation. The first is an electrochemical device for monitoring hydrogen levels in air. The other technology covered in this work, is an acoustic-based approach to determine the state of charge of a hydride storage system.

  12. dsRNA sensors and plasmacytoid dendritic cells in host defense and autoimmunity.

    PubMed

    Wang, Yaming; Swiecki, Melissa; McCartney, Stephen A; Colonna, Marco

    2011-09-01

    The innate immune system detects viruses through molecular sensors that trigger the production of type I interferons (IFN-I) and inflammatory cytokines. As viruses vary tremendously in size, structure, genomic composition, and tissue tropism, multiple sensors are required to detect their presence in various cell types and tissues. In this review, we summarize current knowledge of the diversity, specificity, and signaling pathways downstream of viral sensors and ask whether two distinct sensors that recognize the same viral component are complementary, compensatory, or simply redundant. We also discuss why viral sensors are differentially distributed in distinct cell types and whether a particular cell type dominates the IFN-I response during viral infection. Finally, we review evidence suggesting that inappropriate signaling through viral sensors may induce autoimmunity. The picture emerging from these studies is that disparate viral sensors in different cell types form a dynamic and integrated molecular network that can be exploited for improving vaccination and therapeutic strategies for infectious and autoimmune diseases.

  13. Theoretical and experimental evidence of level repulsion states and evanescent modes in sonic crystal stubbed waveguides

    NASA Astrophysics Data System (ADS)

    Romero-García, V.; Vasseur, J. O.; Garcia-Raffi, L. M.; Hladky-Hennion, A. C.

    2012-02-01

    The complex band structures calculated using the extended plane wave expansion (EPWE) reveal the presence of evanescent modes in periodic systems, never predicted by the classical \\omega(\\vec {k}) methods, providing novel interpretations of several phenomena as well as a complete picture of the system. In this work, we theoretically and experimentally observe that in the ranges of frequencies where a deaf band is traditionally predicted, an evanescent mode with excitable symmetry appears, changing drastically the interpretation of the transmission properties. On the other hand, the simplicity of the sonic crystals in which only the longitudinal polarization can be excited is used to interpret, without loss of generality, the level repulsion between symmetric and antisymmetric bands in sonic crystals as the presence of an evanescent mode connecting both repelled bands. These evanescent modes, obtained using EPWE, explain both the attenuation produced in this range of frequencies and the transfer of symmetry from one band to the other in good agreement with both experimental results and multiple scattering predictions. Thus, the evanescent properties of the periodic system have been revealed to be necessary for the design of new acoustic and electromagnetic applications based on periodicity.

  14. Development of a Microforce Sensor and Its Array Platform for Robotic Cell Microinjection Force Measurement.

    PubMed

    Xie, Yu; Zhou, Yunlei; Lin, Yuzi; Wang, Lingyun; Xi, Wenming

    2016-04-06

    Robot-assisted cell microinjection, which is precise and can enable a high throughput, is attracting interest from researchers. Conventional probe-type cell microforce sensors have some real-time injection force measurement limitations, which prevent their integration in a cell microinjection robot. In this paper, a novel supported-beam based cell micro-force sensor with a piezoelectric polyvinylidine fluoride film used as the sensing element is described, which was designed to solve the real-time force-sensing problem during a robotic microinjection manipulation, and theoretical mechanical and electrical models of the sensor function are derived. Furthermore, an array based cell-holding device with a trapezoidal microstructure is micro-fabricated, which serves to improve the force sensing speed and cell manipulation rates. Tests confirmed that the sensor showed good repeatability and a linearity of 1.82%. Finally, robot-assisted zebrafish embryo microinjection experiments were conducted. These results demonstrated the effectiveness of the sensor working with the robotic cell manipulation system. Moreover, the sensing structure, theoretical model, and fabrication method established in this study are not scale dependent. Smaller cells, e.g., mouse oocytes, could also be manipulated with this approach.

  15. Development of a Microforce Sensor and Its Array Platform for Robotic Cell Microinjection Force Measurement

    PubMed Central

    Xie, Yu; Zhou, Yunlei; Lin, Yuzi; Wang, Lingyun; Xi, Wenming

    2016-01-01

    Robot-assisted cell microinjection, which is precise and can enable a high throughput, is attracting interest from researchers. Conventional probe-type cell microforce sensors have some real-time injection force measurement limitations, which prevent their integration in a cell microinjection robot. In this paper, a novel supported-beam based cell micro-force sensor with a piezoelectric polyvinylidine fluoride film used as the sensing element is described, which was designed to solve the real-time force-sensing problem during a robotic microinjection manipulation, and theoretical mechanical and electrical models of the sensor function are derived. Furthermore, an array based cell-holding device with a trapezoidal microstructure is micro-fabricated, which serves to improve the force sensing speed and cell manipulation rates. Tests confirmed that the sensor showed good repeatability and a linearity of 1.82%. Finally, robot-assisted zebrafish embryo microinjection experiments were conducted. These results demonstrated the effectiveness of the sensor working with the robotic cell manipulation system. Moreover, the sensing structure, theoretical model, and fabrication method established in this study are not scale dependent. Smaller cells, e.g., mouse oocytes, could also be manipulated with this approach. PMID:27058545

  16. Alloy catalysts for fuel cell-based alcohol sensors

    NASA Astrophysics Data System (ADS)

    Ghavidel, Mohammadreza Zamanzad

    Direct ethanol fuel cells (DEFCs) are attractive from both economic and environmental standpoints for generating renewable energy and powering vehicles and portable electronic devices. There is a great interest recently in developing DEFC systems. The cost and performance of the DEFCs are mainly controlled by the Pt-base catalysts used at each electrode. In addition to energy conversion, DEFC technology is commonly employed in the fuel-cell based breath alcohol sensors (BrAS). BrAS is a device commonly used to measure blood alcohol concentration (BAC) and enforce drinking and driving laws. The BrAS is non-invasive and has a fast respond time. However, one of the most important drawback of the commercially available BrAS is the very high loading of Pt employed. One well-known and cost effective method to reduce the Pt loading is developing Pt-alloy catalysts. Recent studies have shown that Pt-transition metal alloy catalysts enhanced the electroactivity while decreasing the required loadings of the Pt catalysts. In this thesis, carbon supported Pt-Mn and Pt-Cu electrocatalysts were synthesized by different methods and the effects of heat treatment and structural modification on the ethanol oxidation reaction (EOR) activity, oxygen reduction reaction (ORR) activity and durability of these samples were thoroughly studied. Finally, the selected Pt-Mn and Pt-Cu samples with the highest EOR activity were examined in a prototype BrAS system and compared to the Pt/C and Pt 3Sn/C commercial electrocatalysts. Studies on the Pt-Mn catalysts produced with and without additives indicate that adding trisodium citrate (SC) to the impregnation solution improved the particle dispersion, decreased particle sizes and reduced the time required for heat treatment. Further studies show that the optimum weight ratio of SC to the metal loading in the impregnation solution was 2:1 and optimum results achieved at pH lower than 4. In addition, powder X-ray diffraction (XRD) analyses indicate

  17. Spiral-path high-sensitivity silicon photonic wire molecular sensor with temperature-independent response.

    PubMed

    Densmore, A; Xu, D-X; Janz, S; Waldron, P; Mischki, T; Lopinski, G; Delâge, A; Lapointe, J; Cheben, P; Lamontagne, B; Schmid, J H

    2008-03-15

    We demonstrate a new silicon photonic wire waveguide evanescent field (PWEF) sensor that exploits the strong evanescent field of the transverse magnetic mode of this high-index-contrast, submicrometer-dimension waveguide. High sensitivity is achieved by using a 2 mm long double-spiral waveguide structure that fits within a compact circular area of 150 microm diameter, facilitating compatibility with commercial spotting apparatus and the fabrication of densely spaced sensor arrays. By incorporating the PWEF sensor element into a balanced waveguide Mach-Zehnder interferometer circuit, a minimum detectable mass of approximately 10 fg of streptavidin protein is demonstrated with near temperature-independent response.

  18. Graphene enhanced evanescent field in microfiber multimode interferometer for highly sensitive gas sensing.

    PubMed

    Yao, B C; Wu, Y; Zhang, A Q; Rao, Y J; Wang, Z G; Cheng, Y; Gong, Y; Zhang, W L; Chen, Y F; Chiang, K S

    2014-11-17

    Graphene based new physics phenomena are leading to a variety of stimulating graphene-based photonic devices. In this study, the enhancement of surface evanescent field by graphene cylindrical cladding is observed, for the first time, by using a graphene-coated microfiber multi-mode interferometer (GMMI). It is found theoretically and experimentally that the light transmitting in the fiber core is efficiently dragged by the graphene, hence significantly enhancing the evanescent fields, and subsequently improving the sensitivity of the hybrid waveguide. The experimental results for gas sensing verified the theoretical prediction, and ultra-high sensitivities of ~0.1 ppm for NH(3) gas detection and ~0.2 ppm for H(2)O vapor detection are achieved, which could be used for trace analysis. The enhancement of surface evanescent field induced by graphene may pave a new way for developing novel graphene-based all-fiber devices with compactness, low cost, and temperature immunity.

  19. Circular and near-circular polarization states of evanescent monochromatic light fields in total internal reflection.

    PubMed

    Azzam, R M A

    2011-11-20

    Conditions for the production of near-circular polarization states of the evanescent field present in the rarer medium in total internal reflection of incident monochromatic p-polarized light at a dielectric-dielectric planar interface are determined. Such conditions are satisfied if high-index (>3.2) transparent prism materials (e.g., GaP and Ge) are used at angles of incidence well above the critical angle but sufficiently below grazing incidence. Furthermore, elliptical polarization of incident light with nonzero p and s components can be tailored to cause circular polarization of the resultant tangential electric field in the plane of the interface or circular polarization of the transverse electric field in a plane normal to the direction of propagation of the evanescent wave. Such polarization control of the evanescent field is significant, e.g., in the fluorescent excitation of molecules adsorbed at solid-liquid and solid-gas interfaces by total internal reflection.

  20. Flight Demonstration Of Low Overpressure N-Wave Sonic Booms And Evanescent Waves

    NASA Astrophysics Data System (ADS)

    Haering, Edward A.; Smolka, James W.; Murray, James E.; Plotkin, Kenneth J.

    2006-05-01

    The recent flight demonstration of shaped sonic booms shows the potential for quiet overland supersonic flight, which could revolutionize air transport. To successfully design quiet supersonic aircraft, the upper limit of an acceptable noise level must be determined through quantitative recording and subjective human response measurements. Past efforts have concentrated on the use of sonic boom simulators to assess human response, but simulators often cannot reproduce a realistic sonic boom sound. Until now, molecular relaxation effects on low overpressure rise time had never been compared with flight data. Supersonic flight slower than the cutoff Mach number, which generates evanescent waves, also prevents loud sonic booms from impacting the ground. The loudness of these evanescent waves can be computed, but flight measurement validation is needed. A novel flight demonstration technique that generates low overpressure N-waves using conventional military aircraft is outlined, in addition to initial quantitative flight data. As part of this demonstration, evanescent waves also will be recorded.

  1. Flight Demonstration Of Low Overpressure N-Wave Sonic Booms And Evanescent Waves

    NASA Technical Reports Server (NTRS)

    Haering, Edward A., Jr.; Smolka, James W.; Murray, James E.; Plotkin, Kenneth J.

    2005-01-01

    The recent flight demonstration of shaped sonic booms shows the potential for quiet overland supersonic flight, which could revolutionize air transport. To successfully design quiet supersonic aircraft, the upper limit of an acceptable noise level must be determined through quantitative recording and subjective human response measurements. Past efforts have concentrated on the use of sonic boom simulators to assess human response, but simulators often cannot reproduce a realistic sonic boom sound. Until now, molecular relaxation effects on low overpressure rise time had never been compared with flight data. Supersonic flight slower than the cutoff Mach number, which generates evanescent waves, also prevents loud sonic booms from impacting the ground. The loudness of these evanescent waves can be computed, but flight measurement validation is needed. A novel flight demonstration technique that generates low overpressure N-waves using conventional military aircraft is outlined, in addition to initial quantitative flight data. As part of this demonstration, evanescent waves also will be recorded.

  2. Gas cell based on cascaded GRIN lens for optical fiber gas sensor

    NASA Astrophysics Data System (ADS)

    Sa, Jiming; Chen, Youping; Zhang, Gang; Zhou, Zude; Cui, Lujun

    2007-12-01

    Based on the theory of gas molecular absorption spectrum, a transmission type gas cell based on cascaded GRIN lens has been designed. The gas cell is the kernel of the optical fiber gas sensor system. The system performance is relative to rationality of gas cell structure. By using GRIN lens couple in gas cell, we can solve the problems of optical discrete components. We use GRIN lens with pigtail fiber as collimating or focusing lens for transmission type of gas cell. To shorten sensor's size and length, and enhance sensor's sensitivity, we present a method by using cascaded GRIN Lens couples to compose a gas cell. With this method, the optical path length is increased and the detection sensitivity of the gas cell is greatly increased. This transmission type of gas cell based on cascaded GRIN lens couples have been applied to our system of absorption spectrum optical fiber gas sensors. We designed and manufactured a gas cell with cascaded GRIN lens couples. Experimental results show that transmission gas cell based on cascaded GRIN lens couples has a good detecting effect.

  3. Fluorescence-lifetime-based sensors using inhomogeneous waveguiding

    NASA Astrophysics Data System (ADS)

    Draxler, Sonja; Kieslinger, Dietmar; Trznadel, Karolina; Lippitsch, Max E.

    1996-12-01

    Most intrinsic fiberoptic sensors are based on the evanescent-wave scheme, where the evanescent field of modes guided in a fiber reaches out into a chemically sensitive coating. In the commonly used multimode waveguides, the evanescent field contains only a small part of the total energy, however, thus making evanescent-wave sensors rather insensitive. Combining a transparent substrate and a transparent sensing layer of rather similar refractive index into a common waveguiding structure produces an inhomogeneous waveguide, where a large portion of the total energy transverses the sensing layer. This yields much superior sensor performance. The transmission through a waveguide is subject to various disturbing influences. Thus it is advantageous to combine the inhomogeneous waveguiding approach with a measuring scheme that is not prone to those disturbances. Such a scheme is available with fluorescence lifetime-based sensors. The fluorescence lifetime of an indicator incorporated into the sensing layer is changed by the presence of the respective analyte. This lifetime is independent of the transmission through the waveguide. Thus inhomogeneous waveguiding together with fluorescence lifetime measurement paves the way for optical chemical sensors with high analyte sensitivity and immunity to external disturbances.

  4. Quantum physics inspired optical effects in evanescently coupled waveguides

    NASA Astrophysics Data System (ADS)

    Thompson, Clinton Edward

    The tight-binding model that has been used for many years in condensed matter physics, due to its analytic and numerical tractability, has recently been used to describe light propagating through an array of evanescently coupled waveguides. This dissertation presents analytic and numerical simulation results of light propagating in a waveguide array. The first result presented is that photonic transport can be achieved in an array where the propagation constant is linearly increasing across the array. For an input at the center waveguide, the breathing modes of the system are observed, while for a phase displaced, asymmetric input, phase-controlled photonic transport is predicted. For an array with a waveguide-dependent, parity-symmetric coupling constant, the wave packet dynamics are predicted to be tunable. In addition to modifying the propagation constant, the coupling between waveguides can also be modified, and the quantum correlations are sensitive to the form of the tunneling function. In addition to modifying the waveguide array parameters in a structured manner, they can be randomized as to mimic the insertion of impurities during the fabrication process. When the refractive indices are randomized and real, the amount of light that localizes to the initial waveguide is found to be dependent on the initial waveguide when the waveguide coupling is non-uniform. In addition, when the variance of the refractive indices is small, light localizes in the initial waveguide as well as the parity-symmetric waveguide. In addition to real valued disorder, complex valued disorder can be introduced into the array through the imaginary component of the refractive index. It is shown that the two-particle correlation function is qualitatively similar to the case when the waveguide coupling is real and random, as both cases preserve the symmetry of the eigenvalues. Lastly, different input fields have been used to investigate the quantum statistical aspects of Anderson

  5. New insights into the nanometer-scaled cell-surface interspace by cell-sensor measurements

    SciTech Connect

    Lehmann, Mirko . E-mail: mirko.lehmann@micronas.com; Baumann, Werner

    2005-05-01

    The culture of adherent cells on solid surfaces is an established in vitro method, and the adhesion process of a cell is considered as an important trigger for many cellular processes (e.g., polarity and tumor genesis). However, not all of the eliciting biochemical or biophysical reactions are yet understood. Interestingly, there are not much experimental data about the impact that the interspace between an adherent cell and the (solid) substrate has on the cell's behavior. This interspace is mainly built by the basolateral side of epithelial cells and the substrate. This paper gives some new results of non-invasive and non-optical measurements in the interspace. The measurements were made with silicon cell-sensor hybrids. Measurements of acidification, adhesion, and respiration are analyzed in view of the situation in the interspace. The results show that, in general, the release of an ion or molecule on the basolateral side can have much more influence on the biophysical situation than a release of an ion or molecule on the apical side. In particular, the apical acidification (i.e., amount of extruded protons) of, e.g., epithelial tumor cells is several orders of magnitude higher than the basolateral acidification. These experimental results are a simple consequence of the fact that the basolateral volume of the interspace is several orders of magnitudes smaller than the apical volume. These results have the following consequences for the cell adhesion:a)static situation: if a cell is already adhered to a solid substrate, the basolateral and apical release and uptake of molecules have to be considered in a very differentiated way; b)dynamic situation: if the cell is adhering to the substrate, the then built basolateral side changes in a much stronger way than the apical side. This effect is here discussed as a possible eliciting and general mechanism for essential intracellular changes.

  6. Wearable Sensor System Powered by a Biofuel Cell for Detection of Lactate Levels in Sweat

    PubMed Central

    Garcia, S. O.; Ulyanova, Y. V.; Figueroa-Teran, R.; Bhatt, K. H.; Singhal, S.; Atanassov, P.

    2016-01-01

    An NAD+-dependent enzymatic sensor with biofuel cell power source system for non-invasive monitoring of lactate in sweat was designed, developed, and tested. The sensor component, based on lactate dehydrogenase, showed linear current response with increasing lactate concentrations with limits of detection from 5 to 100 mM lactate and sensitivity of 0.2 µA.mM−1 in the presence of target analyte. In addition to the sensor patch a power source was also designed, developed and tested. The power source was a biofuel cell designed to oxidize glucose via glucose oxidase. The biofuel cell showed excellent performance, achieving over 80 mA at 0.4 V (16 mW) in a footprint of 3.5 × 3.5 × 0.7 cm. Furthermore, in order to couple the sensor to the power source, system electronic components were designed and fabricated. These consisted of an energy harvester (EH) and a micropotentiostat (MP). The EH was employed for harvesting power provided by the biofuel cell as well as up-converting the voltage to 3.0 V needed for the operation of the MP. The sensor was attached to MP for chronoamperometric detection of lactate. The Sensor Patch System was demonstrated under laboratory conditions. PMID:27375962

  7. Wearable Sensor System Powered by a Biofuel Cell for Detection of Lactate Levels in Sweat.

    PubMed

    Garcia, S O; Ulyanova, Y V; Figueroa-Teran, R; Bhatt, K H; Singhal, S; Atanassov, P

    An NAD(+)-dependent enzymatic sensor with biofuel cell power source system for non-invasive monitoring of lactate in sweat was designed, developed, and tested. The sensor component, based on lactate dehydrogenase, showed linear current response with increasing lactate concentrations with limits of detection from 5 to 100 mM lactate and sensitivity of 0.2 µA.mM(-1) in the presence of target analyte. In addition to the sensor patch a power source was also designed, developed and tested. The power source was a biofuel cell designed to oxidize glucose via glucose oxidase. The biofuel cell showed excellent performance, achieving over 80 mA at 0.4 V (16 mW) in a footprint of 3.5 × 3.5 × 0.7 cm. Furthermore, in order to couple the sensor to the power source, system electronic components were designed and fabricated. These consisted of an energy harvester (EH) and a micropotentiostat (MP). The EH was employed for harvesting power provided by the biofuel cell as well as up-converting the voltage to 3.0 V needed for the operation of the MP. The sensor was attached to MP for chronoamperometric detection of lactate. The Sensor Patch System was demonstrated under laboratory conditions.

  8. Cell-Based Odorant Sensor Array for Odor Discrimination Based on Insect Odorant Receptors.

    PubMed

    Termtanasombat, Maneerat; Mitsuno, Hidefumi; Misawa, Nobuo; Yamahira, Shinya; Sakurai, Takeshi; Yamaguchi, Satoshi; Nagamune, Teruyuki; Kanzaki, Ryohei

    2016-07-01

    The olfactory system of living organisms can accurately discriminate numerous odors by recognizing the pattern of activation of several odorant receptors (ORs). Thus, development of an odorant sensor array based on multiple ORs presents the possibility of mimicking biological odor discrimination mechanisms. Recently, we developed novel odorant sensor elements with high sensitivity and selectivity based on insect OR-expressing Sf21 cells that respond to target odorants by displaying increased fluorescence intensity. Here we introduce the development of an odorant sensor array composed of several Sf21 cell lines expressing different ORs. In this study, an array pattern of four cell lines expressing Or13a, Or56a, BmOR1, and BmOR3 was successfully created using a patterned polydimethylsiloxane film template and cell-immobilizing reagents, termed biocompatible anchor for membrane (BAM). We demonstrated that BAM could create a clear pattern of Sf21 sensor cells without impacting their odorant-sensing performance. Our sensor array showed odorant-specific response patterns toward both odorant mixtures and single odorant stimuli, allowing us to visualize the presence of 1-octen-3-ol, geosmin, bombykol, and bombykal as an increased fluorescence intensity in the region of Or13a, Or56a, BmOR1, and BmOR3 cell lines, respectively. Therefore, we successfully developed a new methodology for creating a cell-based odorant sensor array that enables us to discriminate multiple target odorants. Our method might be expanded into the development of an odorant sensor capable of detecting a large range of environmental odorants that might become a promising tool used in various applications including the study of insect semiochemicals and food contamination.

  9. Vaccinia virus interactions with the cell membrane studied by new chromatic vesicle and cell sensor assays.

    PubMed

    Orynbayeva, Z; Kolusheva, S; Groysman, N; Gavrielov, N; Lobel, L; Jelinek, R

    2007-02-01

    The potential danger of cross-species viral infection points to the significance of understanding the contributions of nonspecific membrane interactions with the viral envelope compared to receptor-mediated uptake as a factor in virus internalization and infection. We present a detailed investigation of the interactions of vaccinia virus particles with lipid bilayers and with epithelial cell membranes using newly developed chromatic biomimetic membrane assays. This analytical platform comprises vesicular particles containing lipids interspersed within reporter polymer units that emit intense fluorescence following viral interactions with the lipid domains. The chromatic vesicles were employed as membrane models in cell-free solutions and were also incorporated into the membranes of epithelial cells, thereby functioning as localized membrane sensors on the cell surface. These experiments provide important insight into membrane interactions with and fusion of virions and the kinetic profiles of these processes. In particular, the data emphasize the significance of cholesterol/sphingomyelin domains (lipid rafts) as a crucial factor promoting bilayer insertion of the viral particles. Our analysis of virus interactions with polymer-labeled living cells exposed the significant role of the epidermal growth factor receptor in vaccinia virus infectivity; however, the data also demonstrated the existence of additional non-receptor-mediated mechanisms contributing to attachment of the virus to the cell surface and its internalization.

  10. Contribution of aquaporins to cellular water transport observed by a microfluidic cell volume sensor.

    PubMed

    Heo, Jinseok; Meng, Fanjie; Hua, Susan Z

    2008-09-15

    Here we demonstrate that an impedance-based microfluidic cell volume sensor can be used to study the roles of aquaporin (AQP) in cellular water permeability and screen AQP-specific drugs. Human embryonic kidney (HEK-293) cells were transiently transfected with AQP3- or AQP4-encoding genes to express AQPs in plasma membranes. The swelling of cells in response to hypotonic stimulation was traced in real time using the sensor. Two time constants were obtained by fitting the swelling curves with a two-exponential function, a fast time constant associated with osmotic water permeability of AQP-expressing cells and a slow phase time constant associated mainly with water diffusion through lipid bilayers in the nontransfected cells. The AQP-expressing cells showed at least 10x faster osmotic water transport than control cells. Using the volume sensor, we examined the effects of Hg (2+) and Ni (2+) on the water transport via AQPs. Hg (2+) inhibited the water flux in AQP3-expressing cells irreversibly, while Ni (2+) blocked the AQP3 channels reversibly. Neither of the two ions blocked the AQP4 channels. The microfluidic volume sensor can sense changes in cell volume in real time, which enables perfusion of various reagents sequentially. It provides a convenient tool for studying the effect of reagents on the function and regulation mechanism of AQPs.

  11. QCL-based TDLAS sensor for detection of NO toward emission measurements from ovarian cancer cells

    NASA Astrophysics Data System (ADS)

    Köhring, M.; Huang, S.; Jahjah, M.; Jiang, W.; Ren, W.; Willer, U.; Caneba, C.; Yang, L.; Nagrath, D.; Schade, W.; Tittel, F. K.

    2014-10-01

    The development of a sensitive sensor for detecting nitric oxide (NO) emissions from biological samples is reported. The sensor is based on tunable diode laser absorption spectroscopy (TDLAS) using a continuous wave, thermoelectrically cooled quantum cascade laser (QCL) and a 100-m astigmatic Herriot cell. A 2 f-wavelength modulation spectroscopy technique was used to obtain QCL-based TDLAS NO emission measurements with an optimum signal-to-noise ratio. An absorption line at 1,900.076 cm-1 was targeted to measure NO with a minimum detection limit of 124 ppt. Positive control measurements with the NO donor DETA NONOate were performed to determine and optimize the sensor performance for measurements of biological samples. Our measurements with NO donor show the potential suitability of the sensor for monitoring NO emission from cancer cells for biological investigations.

  12. Two-photon fluorescent sensor for K+ imaging in live cells (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Sui, Binglin; Yue, Xiling; Kim, Bosung; Belfield, Kevin D.

    2016-03-01

    It is difficult to overstate the physiological importance of potassium for life as its indispensable roles in a variety of biological processes are widely known. As a result, efficient methods for determining physiological levels of potassium are of paramount importance. Despite this, relatively few K+ fluorescence sensors have been reported, with only one being commercially available. A new two-photon excited fluorescent K+ sensor is reported. The sensor is comprised of three moieties, a highly selective K+ chelator as the K+ recognition unit, a boron-dipyrromethene (BODIPY) derivative modified with phenylethynyl groups as the fluorophore, and two polyethylene glycol chains to afford water solubility. The sensor displays very high selectivity (<52-fold) in detecting K+ over other physiological metal cations. Upon binding K+, the sensor switches from non-fluorescent to highly fluorescent, emitting red to near-IR (NIR) fluorescence. The sensor exhibited a good two-photon absorption cross section, 500 GM at 940 nm. Moreover, it is not sensitive to pH in the physiological pH range. Time-dependent cell imaging studies via both one- and two-photon fluorescence microscopy demonstrate that the sensor is suitable for dynamic K+ sensing in living cells.

  13. The Biological Sensor for Detection of Bacterial Cells in Liquid Phase Based on Plate Acoustic Wave

    NASA Astrophysics Data System (ADS)

    Borodina, Irina; Zaitsev, Boris; Shikhabudinov, Alexander; Guliy, Olga; Ignatov, Oleg; Teplykh, Andrey

    The interactions "bacterial cells - bacteriophages", "bacterial cells - antibodies" and "bacterial cells - mini- antibodies" directly in liquid phase were experimentally investigated with a help of acoustic sensor. The acoustic sensor under study represents two-channel delay line based on the plate of Y-X lithium niobate. One channel of delay line was electrically shorted, the second channel was electrically open. The liquid container was glued on plate surface between transducers of delay line. The dependencies of the change in phase and insertion loss on concentration of bacteriophages, antibodies, and mini- antibodies were obtained for both channels of delay line.

  14. Hybridization assay based on evanescent fluorescence excitation and collection

    NASA Astrophysics Data System (ADS)

    Sumner, James J.; Mmerole, Robert U.; Stratis-Cullum, Dimitra N.; Yi, Hyunmin; Bentley, William E.; Gillespie, James B.

    2003-08-01

    There is a great need for high throughput and sensitive sensors for genetic analysis. These sensors can be used for varied purposes from monitoring gene expression in organims to speciation of possible pathogens. Consequently, an instrument capable of these tasks would be a great benefit for food and water safety, medical diagnostics and defense of military and civilian populations from biological threats. This work examines the development of a hybridization-based biosensor using a novel tapered fiber optic rpobe. The immobilization of single-stranded, synthetic ologinucleotides utilizing aminoproplytriethoxysilane and glutaraldehyde was implemented on the fiber optic sensor. Hybridization takes place with a complementary analyte sequence followed by a fluorescent, labeled signaling probe to form a sandwich assay. Following hybridization, the fiber is interrogated with a diode laser source and the resulting fluorescence signal is detected using a miniature spectrometer.

  15. Synaptotagmin-1 and -7 are functionally overlapping Ca2+ sensors for exocytosis in adrenal chromaffin cells

    PubMed Central

    Schonn, Jean-Sébastien; Maximov, Anton; Lao, Ye; Südhof, Thomas C.; Sørensen, Jakob B.

    2008-01-01

    Synaptotagmin-1, the canonical isoform of the synaptotagmin family, is a Ca2+ sensor for fast synchronous neurotransmitter release in forebrain neurons and chromaffin cells. Even though deletion of synaptotagmin-1 abolishes fast exocytosis in chromaffin cells, it reduces overall secretion by only 20% because of the persistence of slow exocytosis. Therefore, another Ca2+ sensor dominates release in these cells. Synaptotagmin-7 has a higher Ca2+ affinity and slower binding kinetics than synaptotagmin-1, matching the proposed properties for the second, slower Ca2+ sensor. Here, we examined Ca2+-triggered exocytosis in chromaffin cells from KO mice lacking synaptotagmin-7, and from knockin mice containing normal levels of a mutant synaptotagmin-7 whose C2B domain does not bind Ca2+. In both types of mutant chromaffin cells, Ca2+-triggered exocytosis was decreased dramatically. Moreover, in chromaffin cells lacking both synaptotagmin-1 and -7, only a very slow release component, accounting for ≈30% of WT exocytosis, persisted. These data establish synaptotagmin-7 as a major Ca2+ sensor for exocytosis in chromaffin cells, which, together with synaptotagmin-1, mediates almost all of the Ca2+ triggering of exocytosis in these cells, a surprising result, considering the lack of a role of synaptotagmin-7 in synaptic vesicle exocytosis. PMID:18308932

  16. Cytosolic DNA Sensor Upregulation Accompanies DNA Electrotransfer in B16.F10 Melanoma Cells

    PubMed Central

    Znidar, Katarina; Bosnjak, Masa; Cemazar, Maja; Heller, Loree C.

    2016-01-01

    In several preclinical tumor models, antitumor effects occur after intratumoral electroporation, also known as electrotransfer, of plasmid DNA devoid of a therapeutic gene. In mouse melanomas, these effects are preceded by significant elevation of several proinflammatory cytokines. These observations implicate the binding and activation of intracellular DNA-specific pattern recognition receptors or DNA sensors in response to DNA electrotransfer. In tumors, IFNβ mRNA and protein levels significantly increased. The mRNAs of several DNA sensors were detected, and DAI, DDX60, and p204 tended to be upregulated. These effects were accompanied with reduced tumor growth and increased tumor necrosis. In B16.F10 cells in culture, IFNβ mRNA and protein levels were significantly upregulated. The mRNAs for several DNA sensors were present in these cells; DNA-dependent activator of interferon regulatory factor (DAI), DEAD (Asp-Glu-Ala-Asp) box polypeptide 60 (DDX60), and p204 were significantly upregulated while DDX60 protein levels were coordinately upregulated. Upregulation of DNA sensors in tumors could be masked by the lower transfection efficiency compared to in vitro or to dilution by other tumor cell types. Mirroring the observation of tumor necrosis, cells underwent a significant DNA concentration-dependent decrease in proliferation and survival. Taken together, these results indicate that DNA electrotransfer may cause the upregulation of several intracellular DNA sensors in B16.F10 cells, inducing effects in vitro and potentially in vivo. PMID:27271988

  17. Rapid and specific electrochemical detection of prostate cancer cells using an aperture sensor array.

    PubMed

    Moscovici, Mario; Bhimji, Alyajahan; Kelley, Shana O

    2013-03-07

    A rapid, simple and specific cancer cell counting sensor would allow for early detection and better disease management. We have developed a novel cell counting device that can specifically count 125 prostate cancer cells in both complex media with serum and a mixed cell population containing non-target cells within 15 min. The microfabricated glass chip with exposed gold apertures utilizes the anti-EpCAM antibody to selectively count prostate cancer cells via differential pulse voltammetry. The newly developed sensor exhibits excellent sensitivity and selectivity. The cells remain viable throughout the counting process and can be used for further analysis. This device could have utility for future applications in early stage cancer diagnosis.

  18. Dye sensitized photovoltaic miniaturized solar cells, used as optical sensors for line of sight detection

    NASA Astrophysics Data System (ADS)

    Cesar, Cortes Torres Carlos; Sampei, Kota; Miho, Ogawa; Masataka, Ozawa; Norihisa, Miki

    2014-11-01

    Dye sensitized photovoltaic devices have been studied as transparent and low-cost solar cells. Our group have miniaturized the cells and used them as transparent optical sensors. This paper reports the design and fabrication of the cells and avoids the cross talk among cells, which was found recently and such effect provokes hardware instability. We use these optical sensors as an eye tracking device. The sensor array detects the difference in the intensity of light reflected from the pupil and the sclera and then determines the pupil position. Each sensor consists of two electrodes and electrolyte; hence our device conformed by only four semi-circular shaped sensors on eyeglasses can detect the view angle in both horizontal and vertical directions. Manufacturing process gives us freedom to easily re-arrange, add or remove sensors. In our prior work we had good performance in stand-alone configuration. We used specialized equipment from National Instruments for our measurements. However we found that: A cell is not 100% independent from the others, is affected by the absence or presence of light at the neighbour cells. When our device is connected to other electronic devices (for data processing), all cells have the same voltage among them; therefore, all cells behave the same way when any of them is affected by light. The root cause is, due to all sensors were interconnected via a micro channel and filled with electrolyte, due to its conductive properties, electrolyte does neither need electrodes nor physical paths to conduct electricity, so it creates a liquid wire between sensors, hence the gap between them become inexistent, consequently when our device is connected to other electronic devices, due to this unique channel and by sharing a common electronic ground, this connection provokes the voltage to be the same among all sensors in the array. Our device becomes four separate voltage lines in a parallel circuit. The device was also in short circuit provoked

  19. Acoustic sensor for monitoring adhesion of Neuro-2A cells in real-time.

    PubMed

    Khraiche, Massoud Louis; Zhou, Anhong; Muthuswamy, Jit

    2005-05-15

    Neuronal adhesion plays a fundamental role in growth, migration, regeneration and plasticity of neurons. However, current methods for studying neuronal adhesion cannot monitor this phenomenon quantitatively in real-time. In this work, we demonstrate the use of an acoustic sensor to measure adhesion of neuro-blastoma cells (Neuro-2A) in real-time. An acoustic sensor consisting of a quartz crystal sandwiched between gold electrodes was placed in a flow cell and filled with 600 microl of phosphate buffered saline (PBS). Two sets of in vitro experiments were performed using sensors that had uncoated gold electrodes and sensors that were coated with a known neuronal adhesion promoter (poly-l-lysine or PLL). The instantaneous resonant frequency and the equivalent motional resistance of the acoustic sensor were monitored every second. Cell Tracker was used to confirm neuronal adhesion to the surface. Addition of 10 microl of media and Neuro-2A cells into the above set-up elicited exponential changes in the resonant frequency and motional resistance of the quartz crystal with time to reach steady state in the range of 2-11 h. The steady-state change in resonant frequency in response to addition of neurons was linearly related to the number of Neuro-2A cells added (R2=0.94). Acoustic sensors coated with the adhesion promoter, PLL showed a much higher change in resonant frequency for approximately the same number of neurons. We conclude that the acoustic sensor has sufficient sensitivity to monitor neuronal adhesion in real-time. This has potential applications in the study of mechanisms of neuron-substrate interactions and the effect of molecular modulators in the extra cellular matrix.

  20. Cell-surface sensors for real-time probing of cellular environments

    NASA Astrophysics Data System (ADS)

    Zhao, Weian; Schafer, Sebastian; Choi, Jonghoon; Yamanaka, Yvonne J.; Lombardi, Maria L.; Bose, Suman; Carlson, Alicia L.; Phillips, Joseph A.; Teo, Weisuong; Droujinine, Ilia A.; Cui, Cheryl H.; Jain, Rakesh K.; Lammerding, Jan; Love, J. Christopher; Lin, Charles P.; Sarkar, Debanjan; Karnik, Rohit; Karp, Jeffrey M.

    2011-08-01

    The ability to explore cell signalling and cell-to-cell communication is essential for understanding cell biology and developing effective therapeutics. However, it is not yet possible to monitor the interaction of cells with their environments in real time. Here, we show that a fluorescent sensor attached to a cell membrane can detect signalling molecules in the cellular environment. The sensor is an aptamer (a short length of single-stranded DNA) that binds to platelet-derived growth factor (PDGF) and contains a pair of fluorescent dyes. When bound to PDGF, the aptamer changes conformation and the dyes come closer to each other, producing a signal. The sensor, which is covalently attached to the membranes of mesenchymal stem cells, can quantitatively detect with high spatial and temporal resolution PDGF that is added in cell culture medium or secreted by neighbouring cells. The engineered stem cells retain their ability to find their way to the bone marrow and can be monitored in vivo at the single-cell level using intravital microscopy.

  1. Cell-surface sensors for real-time probing of cellular environments

    PubMed Central

    Zhao, Weian; Schafer, Sebastian; Choi, Jonghoon; Yamanaka, Yvonne J.; Lombardi, Maria L.; Bose, Suman; Carlson, Alicia L.; Phillips, Joseph A.; Teo, Weisuong; Droujinine, Ilia A.; Cui, Cheryl H.; Jain, Rakesh K.; Lammerding, Jan; Love, J. Christopher; Lin, Charles P.; Sarkar, Debanjan; Karnik, Rohit; Karp, Jeffrey M.

    2011-01-01

    The ability to explore cell signalling and cell-to-cell communication is essential for understanding cell biology and developing effective therapeutics. However, it is not yet possible to monitor the interaction of cells with their environments in real time. Here, we show that a fluorescent sensor attached to a cell membrane can detect signalling molecules in the cellular environment. The sensor is an aptamer (a short length of single-stranded DNA) that binds to platelet-derived growth factor (PDGF) and contains a pair of fluorescent dyes. When bound to PDGF, the aptamer changes conformation and the dyes come closer to each other, producing a signal. The sensor, which is covalently attached to the membranes of mesenchymal stem cells, can quantitatively detect with high spatial and temporal resolution PDGF that is added in cell culture medium or secreted by neighbouring cells. The engineered stem cells retain their ability to find their way to the bone marrow and can be monitored in vivo at the single-cell level using intravital microscopy. PMID:21765401

  2. Visualization of glutamine transporter activities in living cells using genetically encoded glutamine sensors.

    PubMed

    Gruenwald, Katrin; Holland, John Todd; Stromberg, Verlyn; Ahmad, Altaf; Watcharakichkorn, Daisy; Okumoto, Sakiko

    2012-01-01

    Glutamine plays a central role in the metabolism of critical biological molecules such as amino acids, proteins, neurotransmitters, and glutathione. Since glutamine metabolism is regulated through multiple enzymes and transporters, the cellular glutamine concentration is expected to be temporally dynamic. Moreover, differentiation in glutamine metabolism between cell types in the same tissue (e.g. neuronal and glial cells) is often crucial for the proper function of the tissue as a whole, yet assessing cell-type specific activities of transporters and enzymes in such heterogenic tissue by physical fractionation is extremely challenging. Therefore, a method of reporting glutamine dynamics at the cellular level is highly desirable. Genetically encoded sensors can be targeted to a specific cell type, hence addressing this knowledge gap. Here we report the development of Föster Resonance Energy Transfer (FRET) glutamine sensors based on improved cyan and yellow fluorescent proteins, monomeric Teal Fluorescent Protein (mTFP)1 and venus. These sensors were found to be specific to glutamine, and stable to pH-changes within a physiological range. Using cos7 cells expressing the human glutamine transporter ASCT2 as a model, we demonstrate that the properties of the glutamine transporter can easily be analyzed with these sensors. The range of glutamine concentration change in a given cell can also be estimated using sensors with different affinities. Moreover, the mTFP1-venus FRET pair can be duplexed with another FRET pair, mAmetrine and tdTomato, opening up the possibility for real-time imaging of another molecule. These novel glutamine sensors will be useful tools to analyze specificities of glutamine metabolism at the single-cell level.

  3. Optical nanosensors for chemical analysis inside single living cells. 2. Sensors for pH and calcium and the intracellular application of PEBBLE sensors.

    PubMed

    Clark, H A; Kopelman, R; Tjalkens, R; Philbert, M A

    1999-11-01

    Optical nanosensors, or PEBBLEs (probes encapsulated by biologically localized embedding), have been produced for intracellular measurements of pH and calcium. Five varieties of pH-sensitive sensors and three different calcium-selective sensors are presented and discussed. Each sensor combines an ion-selective fluorescent indicator and an ion-insensitive internal standard entrapped within an acrylamide polymeric matrix. Calibrations and linear ranges are presented for each sensor. The photobleaching of dyes incorporated into PEBBLEs is comparable to that of the respective free dye that is incorporated within the matrix. These PEBBLE sensors are fully reversible over many measurements. The leaching of fluorescent indicator from the polymer is less than 50% over a 48-h period (note that a typical application time is only a few hours). The PEBBLE sensors have also been applied to intracellular analysis of the calcium flux in the cytoplasm of neural cells during the mitochondrial permeability transition. Specifically, a distinct difference is noted between cells of different types (astrocyte vs neuron-derived cells) with respect to their response to the toxicant m-dinitrobenzene (DNB). Use of PEBBLE sensors permits the quantitative discrimination of subtle differences between the ability of human SY5Y neuroblastoma and C6 glioma to respond to challenge with DNB. Specifically, measurement of intracellular calcium, the precursor to cell death, has been achieved.

  4. Thermal microphotonic sensor and sensor array

    DOEpatents

    Watts, Michael R.; Shaw, Michael J.; Nielson, Gregory N.; Lentine, Anthony L.

    2010-02-23

    A thermal microphotonic sensor is disclosed for detecting infrared radiation using heat generated by the infrared radiation to shift the resonant frequency of an optical resonator (e.g. a ring resonator) to which the heat is coupled. The shift in the resonant frequency can be determined from light in an optical waveguide which is evanescently coupled to the optical resonator. An infrared absorber can be provided on the optical waveguide either as a coating or as a plate to aid in absorption of the infrared radiation. In some cases, a vertical resonant cavity can be formed about the infrared absorber to further increase the absorption of the infrared radiation. The sensor can be formed as a single device, or as an array for imaging the infrared radiation.

  5. Evanescent Microwave Probes Using Coplanar Waveguide and Stripline for Super-Resolution Imaging of Materials

    NASA Technical Reports Server (NTRS)

    Ponchak, G. E.; Akinwande, D.; Ciocan, R.; LeClair, S. R.; Tabib-Azar, M.

    2000-01-01

    An evanescent field microwave imaging probe based on half-wavelength, microwave transmission line resonators is described. Optimization of the probe tip design, the coupling gap, and the data analysis has resulted in images of metal lines on semiconductor substrates with 2.6 microns spatial resolution and a minimum detectable line width of 0.4 microns at 1 GHz.

  6. Strong coupling of gold dipolar nanoantennas by symmetry-breaking in evanescent wave

    NASA Astrophysics Data System (ADS)

    Yang, Jhen-Hong; Chen, Kuo-Ping

    2016-09-01

    Observing the resonance wavelengths of nanoantennas (NAs) with changing incident angles in TM and TE polarization. Extinction cross section shows the dark and bright coupling modes at resonance wavelength of NAs with symmetry breaking oblique incidence. The plasmonic enhancement is stronger under evanescent wave in total internal reflection.

  7. A Portable Cell-Based Impedance Sensor for Toxicity Testing of Drinking Water

    DTIC Science & Technology

    2009-05-07

    filled with MEM + 0.5% BSA, and a fluidic biochip with a confluent monolayer of BPAECs was assembled into the instrument in a laminar flow hood to allow...disposable media delivery system. The toxicity sensor monitors changes in impedance of cell monolayers on the biochips after the introduction of water...supporting cell health over extended periods of time and obtaining impedance measurements from endothelial cell monolayers after toxicant exposure

  8. Engineering a growth sensor to select intracellular antibodies in the cytosol of mammalian cells.

    PubMed

    Nguyen, Thuy Duong; Takasuka, Hitoshi; Kaku, Yoshihiro; Inoue, Satoshi; Nagamune, Teruyuki; Kawahara, Masahiro

    2017-03-16

    Intracellular antibodies (intrabodies) are expected to function as therapeutics as well as tools for elucidating in vivo function of proteins. In this study, we propose a novel intrabody selection method in the cytosol of mammalian cells by utilizing a growth signal, induced by the interaction of the target antigen and an scFv-c-kit growth sensor. Here, we challenge this method to select specific intrabodies against rabies virus nucleoprotein (RV-N) for the first time. As a result, we successfully select antigen-specific intrabodies from a naïve synthetic library using phage panning followed by our growth sensor-based intracellular selection method, demonstrating the feasibility of the method. Additionally, we succeed in improving the response of the growth sensor by re-engineering the linker region of its construction. Collectively, the described selection method utilizing a growth sensor may become a highly efficient platform for selection of functional intrabodies in the future.

  9. Visualization of Synaptic Inhibition with an Optogenetic Sensor Developed by Cell-Free Protein Engineering Automation

    PubMed Central

    Grimley, Joshua S.; Li, Li; Wang, Weina; Wen, Lei; Beese, Lorena S.

    2013-01-01

    We describe an engineered fluorescent optogenetic sensor, SuperClomeleon, that robustly detects inhibitory synaptic activity in single, cultured mouse neurons by reporting intracellular chloride changes produced by exogenous GABA or inhibitory synaptic activity. Using a cell-free protein engineering automation methodology that bypasses gene cloning, we iteratively constructed, produced, and assayed hundreds of mutations in binding-site residues to identify improvements in Clomeleon, a first-generation, suboptimal sensor. Structural analysis revealed that these improvements involve halide contacts and distant side chain rearrangements. The development of optogenetic sensors that respond to neural activity enables cellular tracking of neural activity using optical, rather than electrophysiological, signals. Construction of such sensors using in vitro protein engineering establishes a powerful approach for developing new probes for brain imaging. PMID:24107961

  10. Evanescent field enhancement due to plasmonic resonances of a metamaterial slab.

    PubMed

    Chiu, K P; Kao, T S; Tsai, D P

    2008-02-01

    The characteristics of plasmonic resonance in a dielectric-sandwiched metamaterial film at visible wavelengths of 650 and 568 nm have been investigated (for both p- and s-polarized light). Our calculated results demonstrate that each mode of plasmonic resonance has maximum resonance strength at a particular film thickness of the metamaterial. We also demonstrated that the effect of evanescent field enhancement is due to plasmonic resonances of the sandwiched metamaterial system. And the stronger the plasmonic resonance strength the larger the evanescent field is enhanced at the interfaces of the metamaterial film. Also we see that the plasmonic resonances in a sandwiched metamaterial are influenced not only by the materials that constitute the interfaces but also by the thickness of surrounding dielectrics or distance between evanescent light source and metamaterial film. Finally, our results show that there might be an effective light propagation length that will let the coupling efficiency between evanescent light source and SPs resonance become a maximum. These properties of plasmonic resonances to structure parameters of metamaterial film and its surrounding dielectrics provide a useful way to control the optical responses of an optoelectronic device when the wavelength of light source is fixed. That is, by suitably choosing light polarizations, thickness of the metamaterial thin film or the surrounding dielectrics and the position of evanescent light source, it is possible to modulate the plasmonic resonance wavenumber or resonance strength of the system. Therefore, the optical responses of the system can be modulated. Our results will be helpful for the structure design to control the behaviours of coupled plasmonic resonances and consequently the optical properties of the dielectric-sandwiched metamaterial film.

  11. 3.0-3.7μm infrared sensor system for cell analysis

    NASA Astrophysics Data System (ADS)

    van den Driesche, Sander; Witarski, Wojciech; Vellekoop, Michael J.

    2009-05-01

    In this contribution we present a novel LED-photodiode based infrared absorbance sensor in the wavelength range of 3.0 - 3.7 μm for cell analysis. Instead of using time consuming and expensive labelling and staining techniques to distinguish healthy from malignant cell types, this IR sensor system can perform faster, cheaper and without the need of additional chemicals. Depending on the used narrow bandpass filters, absorbance due to specific molecular vibration can be measured, such as the functional absorbance peaks at 3.38 μm (CH3-antisymmetric stretch), 3.42 μm (CH2- antisymmetric stretch), 3.48 μm (CH3-symmetric stretch) and 3.51 μm (CH2-symmetric stretch). For normalization and baseline correction the absorbance at wavelengths 3.33 and 3.57 μm are used. By recording the IR absorbance spectra of healthy and malignant epithelial kidney cell lines with an IR spectroscope, we found significant differences in the absorbance ratio 3.51 μm / 3.42 μm (CH2-symmetric/antisymmetric stretch). This result has led us to a sensor concept where only four wavelengths are being measured. In the 3.0 - 3.7 μm wavelength region a low cost LED-photodiode system can be used instead of a spectroscope. Yeast cells, which also contain the CH2 symmetric and antisymmetric stretch bands, are used to validate this sensor system and to make a first comparison of the system to spectroscopic recordings. Sensor experiments on dried spots of baker's yeast on calcium-fluoride slides yielded a comparable CH2 stretch ratio with the IR spectroscope measurement. This confirms the usability of the sensor to measure the CH2 stretch ratio and its potential for fast, label-free and low cost screening of cell samples.

  12. Sensor Needs and Requirements for Fuel Cells and CIDI/SIDI Engines

    SciTech Connect

    Glass, R.S.

    2000-03-01

    To reduce U.S. dependence on imported oil, improve urban air quality, and decrease greenhouse gas emissions, the Department of Energy (DOE) is developing advanced vehicle technologies and fuels. Enabling technologies for fuel cell power systems and direct-injection engines are being developed by DOE through the Partnership for a New Generation of Vehicles (PNGV), a government-industry collaboration to produce vehicles having up to three times the fuel economy of conventional mid-size automobiles. Sensors have been identified as a research and development need for both fuel cell and direct-injection systems, because current sensor technologies do not adequately meet requirements. Sensors are needed for emission control, for passenger safety and comfort, to increase system lifetime, and for system performance enhancement through feedback and control. These proceedings document the results of a workshop to define sensor requirements for proton exchange membrane (PEM) fuel cell systems and direct-injection engines for automotive applications. The recommendations from this workshop will be incorporated into the multi-year R&D plan of the DOE Office of Advanced Automotive Technologies. The objectives of the workshop were to: define the requirements for sensors; establish R&D priorities; identify the technical targets and technical barriers; and facilitate collaborations among participants. The recommendations from this workshop will be incorporated into the multi-year R&D plan of the DOE Office of Advanced Automotive Technologies.

  13. Cell suspension concentration monitoring by using a miniaturized serial high frequency SAWR sensor

    PubMed Central

    Li, Jian; Feng, Hailin; Fang, Yiming

    2015-01-01

    In this paper, a miniaturized cell suspension concentration monitoring method was investigated. The sensing unit was a carbon screen-printed electrode (CSPE) in serial with a 433MHz vacuum-packaged surface acoustic wave resonator (SAWR). SAWR provided a stable and high operating frequency, which helps to keep the stability and sensitivity of the monitoring system. Living cells suspensions in different concentrations were prepared and dropcast on CSPE. Frequency responses of the sensor were recorded. Cell quantity variation within the same culture media volume changed the dielectric properties of CSPE and finally affected the SAWR frequency. SAWR frequency declined with the decrease of cell concentration. The proposed sensor provided high sensitivity and remarkable stability for the cell suspensions. PMID:26588250

  14. A Sensitive Sensor Cell Line for the Detection of Oxidative Stress Responses in Cultured Human Keratinocytes

    PubMed Central

    Hofmann, Ute; Priem, Melanie; Bartzsch, Christine; Winckler, Thomas; Feller, Karl-Heinz

    2014-01-01

    In the progress of allergic and irritant contact dermatitis, chemicals that cause the generation of reactive oxygen species trigger a heat shock response in keratinocytes. In this study, an optical sensor cell line based on cultured human keratinocytes (HaCaT cells) expressing green fluorescent protein (GFP) under the control of the stress-inducible HSP70B' promoter were constructed. Exposure of HaCaT sensor cells to 25 μM cadmium, a model substance for oxidative stress induction, provoked a 1.7-fold increase in total glutathione and a ∼300-fold induction of transcript level of the gene coding for heat shock protein HSP70B'. An extract of Arnica montana flowers resulted in a strong induction of the HSP70B' gene and a pronounced decrease of total glutathione in keratinocytes. The HSP70B' promoter-based sensor cells conveniently detected cadmium-induced stress using GFP fluorescence as read-out with a limit of detection of 6 μM cadmium. In addition the sensor cells responded to exposure of cells to A. montana extract with induction of GFP fluorescence. Thus, the HaCaT sensor cells provide a means for the automated detection of the compromised redox status of keratinocytes as an early indicator of the development of human skin disorders and could be applied for the prediction of skin irritation in more complex in vitro 3D human skin models and in the development of micro-total analysis systems (μTAS) that may be utilized in dermatology, toxicology, pharmacology and drug screenings. PMID:24967604

  15. A sensitive sensor cell line for the detection of oxidative stress responses in cultured human keratinocytes.

    PubMed

    Hofmann, Ute; Priem, Melanie; Bartzsch, Christine; Winckler, Thomas; Feller, Karl-Heinz

    2014-06-25

    In the progress of allergic and irritant contact dermatitis, chemicals that cause the generation of reactive oxygen species trigger a heat shock response in keratinocytes. In this study, an optical sensor cell line based on cultured human keratinocytes (HaCaT cells) expressing green fluorescent protein (GFP) under the control of the stress-inducible HSP70B' promoter were constructed. Exposure of HaCaT sensor cells to 25 µM cadmium, a model substance for oxidative stress induction, provoked a 1.7-fold increase in total glutathione and a ~300-fold induction of transcript level of the gene coding for heat shock protein HSP70B'. An extract of Arnica montana flowers resulted in a strong induction of the HSP70B' gene and a pronounced decrease of total glutathione in keratinocytes. The HSP70B' promoter-based sensor cells conveniently detected cadmium-induced stress using GFP fluorescence as read-out with a limit of detection of 6 µM cadmium. In addition the sensor cells responded to exposure of cells to A. montana extract with induction of GFP fluorescence. Thus, the HaCaT sensor cells provide a means for the automated detection of the compromised redox status of keratinocytes as an early indicator of the development of human skin disorders and could be applied for the prediction of skin irritation in more complex in vitro 3D human skin models and in the development of micro-total analysis systems (µTAS) that may be utilized in dermatology, toxicology, pharmacology and drug screenings.

  16. Investigation of the electrode kinetics in a solid oxide fuel cell and an oxygen sensor

    NASA Astrophysics Data System (ADS)

    Radhakrishnan, Rajesh

    This dissertation investigates the electrode kinetics in a solid oxide fuel cell and an oxygen sensor. The first chapter describes the basics of fuel cell and motivation behind the studies. The second chapter investigates the dependence of cathodic charge transfer reaction resistance (Rct), on three-phase boundary length (lTPB) at various temperatures and oxygen partial pressures ( pO2 ). Impedance spectra were obtained using three-electrode configuration on discs having cathodes with definite lTPB to investigate the La0.8Sr0.2MnO3 (LSM)-Y 0.16Zr0.84O2 (YSZ), platinum (Pt)-YSZ and La 0.8Sr0.2CoO3 (LSC)-Ce0.8Sm0.2 O2 (SDC) half cell reactions at temperatures between 650--800°C and pO2 between 10-3 to 1 atm. For LSM-YSZ and Pt-YSZ, 1/Rct varies linearly with lTPB. LSC-SDC system did not show any specific dependence between R ct and lTPB. The third chapter examines the use of an electrolyte supported cell with externally applied voltage to determine the single electrode overpotential and extending the parameters derived to that of an anode supported fuel cell having thin film electrolyte operating under a chemical potential gradient. Spatial distributions of the electrochemical potential of electrons (ϕ) and oxygen ions ( m˜O-2 ), and chemical potential of oxygen ( mO2 ) for these two cases were obtained. Under fuel cell operating conditions, ϕ, m˜O-2 and mO2 , decreases monotonically from higher value to lower value. For electrolyte supported cell under externally applied voltage mO2 does not vary monotonically; it reaches values above or below that of the boundary values, leading to development of internal electromotive forces (EMFs), which can in turn affect the activity of the interface. The fourth chapter describes design microfabrication and characterization of a series connected potentiometric oxygen sensor. A drawback of potentiometric sensors in general is that the output signal is low when the ratio of the partial pressures at the two electrodes is low

  17. Submersible microbial fuel cell sensor for monitoring microbial activity and BOD in groundwater: focusing on impact of anodic biofilm on sensor applicability.

    PubMed

    Zhang, Yifeng; Angelidaki, Irini

    2011-10-01

    A sensor, based on a submersible microbial fuel cell (SUMFC), was developed for in situ monitoring of microbial activity and biochemical oxygen demand (BOD) in groundwater. Presence or absence of a biofilm on the anode was a decisive factor for the applicability of the sensor. Fresh anode was required for application of the sensor for microbial activity measurement, while biofilm-colonized anode was needed for utilizing the sensor for BOD content measurement. The current density of SUMFC sensor equipped with a biofilm-colonized anode showed linear relationship with BOD content, to up to 250 mg/L (∼233 ± 1 mA/m(2)), with a response time of <0.67 h. This sensor could, however, not measure microbial activity, as indicated by the indifferent current produced at varying active microorganisms concentration, which was expressed as microbial adenosine-triphosphate (ATP) concentration. On the contrary, the current density (0.6 ± 0.1 to 12.4 ± 0.1 mA/m(2)) of the SUMFC sensor equipped with a fresh anode showed linear relationship, with active microorganism concentrations from 0 to 6.52 nmol-ATP/L, while no correlation between the current and BOD was observed. It was found that temperature, pH, conductivity, and inorganic solid content were significantly affecting the sensitivity of the sensor. Lastly, the sensor was tested with real contaminated groundwater, where the microbial activity and BOD content could be detected in <3.1 h. The microbial activity and BOD concentration measured by SUMFC sensor fitted well with the one measured by the standard methods, with deviations ranging from 15% to 22% and 6% to 16%, respectively. The SUMFC sensor provides a new way for in situ and quantitative monitoring contaminants content and biological activity during bioremediation process in variety of anoxic aquifers.

  18. Microbial fuel cells as power supply of a low-power temperature sensor

    NASA Astrophysics Data System (ADS)

    Khaled, Firas; Ondel, Olivier; Allard, Bruno

    2016-02-01

    Microbial fuel cells (MFCs) show great promise as a concomitant process for water treatment and as renewable energy sources for environmental sensors. The small energy produced by MFCs and the low output voltage limit the applications of MFCs. Specific converter topologies are required to step-up the output voltage of a MFC. A Power Management Unit (PMU) is proposed for operation at low input voltage and at very low power in a completely autonomous way to capture energy from MFCs with the highest possible efficiency. The application of sensors for monitoring systems in remote locations is an important approach. MFCs could be an alternative energy source in this case. Powering a sensor with MFCs may prove the fact that wastewater may be partly turned into renewable energy for realistic applications. The Power Management Unit is demonstrated for 3.6 V output voltage at 1 mW continuous power, based on a low-cost 0.7-L MFC. A temperature sensor may operate continuously on 2-MFCs in continuous flow mode. A flyback converter under discontinuous conduction mode is also tested to power the sensor. One continuously fed MFC was able to efficiently and continuously power the sensor.

  19. Formation, encapsulation, and validation of membrane-based artificial hair cell sensors

    NASA Astrophysics Data System (ADS)

    Garrison, Kevin L.; Sarles, Stephen A.; Leo, Donald J.

    2012-04-01

    Hair cell structures are one of the most common forms of sensing elements found in nature. In nearly all vertebrates hair cells are used for auditory and vestibular sensing. In humans, approximately 16,000 auditory hair cells can be found in the cochlea of the ear. Each hair cell contains a stereocilia, which is the primary structure for sound transduction. This study looks to develop and characterize an artificial hair cell that resembles the stereocilia of the human ear. Recently our research group has shown that a single artificial hair cell can be formed in an open substrate using a single aqueous droplet and a hydrogel. In this study, air was blown across the hair and analyzed using spectral analysis. The results of this study provided the foundation for our current work toward an artificial hair cell that uses two aqueous droplets. In the current study a test fixture was created in order to consistently measure various properties of the encapsulated hair cell. The response of the hair cell was measured with an impulse input at various locations on the test fixture. A frequency response function was then created using the impulse input and the output of the sensor. It was found that the vibration of the hair was only detectable if the test fixture was struck at the correct location. By changing the physical parameters of the hair sensor, such as hair length, we were able to alter the response of the sensor. It was also found that the sensitivity of the sensor was reliant on the size of the lipid bilayer.

  20. Fabrication and Evaluation of a Micro(Bio)Sensor Array Chip for Multiple Parallel Measurements of Important Cell Biomarkers

    PubMed Central

    Pemberton, Roy M.; Cox, Timothy; Tuffin, Rachel; Drago, Guido A.; Griffiths, John; Pittson, Robin; Johnson, Graham; Xu, Jinsheng; Sage, Ian C.; Davies, Rhodri; Jackson, Simon K.; Kenna, Gerry; Luxton, Richard; Hart, John P.

    2014-01-01

    This report describes the design and development of an integrated electrochemical cell culture monitoring system, based on enzyme-biosensors and chemical sensors, for monitoring indicators of mammalian cell metabolic status. MEMS technology was used to fabricate a microwell-format silicon platform including a thermometer, onto which chemical sensors (pH, O2) and screen-printed biosensors (glucose, lactate), were grafted/deposited. Microwells were formed over the fabricated sensors to give 5-well sensor strips which were interfaced with a multipotentiostat via a bespoke connector box interface. The operation of each sensor/biosensor type was examined individually, and examples of operating devices in five microwells in parallel, in either potentiometric (pH sensing) or amperometric (glucose biosensing) mode are shown. The performance characteristics of the sensors/biosensors indicate that the system could readily be applied to cell culture/toxicity studies. PMID:25360580

  1. Nanomechanical sensors for single microbial cell growth monitoring

    NASA Astrophysics Data System (ADS)

    Maloney, Niall; Lukacs, Gyongyi; Jensen, Jason; Hegner, Martin

    2014-06-01

    A nanomechanical technique for rapid real time detection and monitoring of microorganism growth will significantly reduce costs and diagnosis times in industrial and clinical settings. Owing to their label free detection mechanism and unprecedented sensitivity to the mass and elastic modulus of biological structures, dynamically operated cantilever arrays provide an opportunity to rapidly detect and track the evolution of microbial growth. Here we report the monitoring of the growth of single Aspergillus niger spores via the multimode response of microcantilevers. The fungal hyphal structure affects the cantilevers' nanomechanical properties as it propagates along the sensor. We demonstrate, for the first time, the mapping of cellular events with great accuracy using a cantilever frequency response. Imaging of growth conditions on the cantilever, which is performed in parallel, allows for verification of these results. Theoretical comparison and finite element modelling confirm experimental findings and allow for determination of the hyphal elastic modulus.A nanomechanical technique for rapid real time detection and monitoring of microorganism growth will significantly reduce costs and diagnosis times in industrial and clinical settings. Owing to their label free detection mechanism and unprecedented sensitivity to the mass and elastic modulus of biological structures, dynamically operated cantilever arrays provide an opportunity to rapidly detect and track the evolution of microbial growth. Here we report the monitoring of the growth of single Aspergillus niger spores via the multimode response of microcantilevers. The fungal hyphal structure affects the cantilevers' nanomechanical properties as it propagates along the sensor. We demonstrate, for the first time, the mapping of cellular events with great accuracy using a cantilever frequency response. Imaging of growth conditions on the cantilever, which is performed in parallel, allows for verification of these

  2. Low temperature co-fired ceramic packaging of CMOS capacitive sensor chip towards cell viability monitoring

    PubMed Central

    Kilpijärvi, Joni; Sobocinski, Maciej; Datta-Chaudhuri, Timir; Hassinen, Antti; Prakash, Someshekar B; Möller, Peter; Abshire, Pamela; Kellokumpu, Sakari; Lloyd Spetz, Anita

    2016-01-01

    Cell viability monitoring is an important part of biosafety evaluation for the detection of toxic effects on cells caused by nanomaterials, preferably by label-free, noninvasive, fast, and cost effective methods. These requirements can be met by monitoring cell viability with a capacitance-sensing integrated circuit (IC) microchip. The capacitance provides a measurement of the surface attachment of adherent cells as an indication of their health status. However, the moist, warm, and corrosive biological environment requires reliable packaging of the sensor chip. In this work, a second generation of low temperature co-fired ceramic (LTCC) technology was combined with flip-chip bonding to provide a durable package compatible with cell culture. The LTCC-packaged sensor chip was integrated with a printed circuit board, data acquisition device, and measurement-controlling software. The packaged sensor chip functioned well in the presence of cell medium and cells, with output voltages depending on the medium above the capacitors. Moreover, the manufacturing of microfluidic channels in the LTCC package was demonstrated. PMID:28144536

  3. A bio-inspired aquatic flow sensor using an artificial cell membrane

    NASA Astrophysics Data System (ADS)

    Pinto, Preston A.; Garrison, Kevin; Leo, Donald J.; Sarles, Stephen A.

    2012-04-01

    Receptors known as hair cells give many animals this ability to sense a wide range of stimuli, such as sound, orientation, vibration, and flow. Previous researchers have mimicked natural hair cells by building electromechanical sensor systems that produce an electric response due to the bending of artificial hairs. Inspired by the roles of sensory hairs in fish, this work builds on previous research by investigating the flow dependent electrical response of a 'skin'-encapsulated artificial hair cell in an aqueous flow. This study presents the design, fabrication, and characterization of a flow sensor that will help close the loop between the sensing mechanisms and control strategies that aquatic organisms employ for functions such as locomotion regulation, prey capture, and particulate capture. The system is fabricated with a durable, artificial bilayer that forms at the interface between lipid-encased aqueous volumes contained in a flexible encapsulated polyurethane substrate. Flow experiments are conducted by placing the bio-inspired sensor in a flow chamber and subjecting it to pulse-like flows. Specifically, through temporal responses of the measured current and power spectral density (PSD) analysis, our results show that the amplitude and frequency of the current response are related to the flow over the hair. This preliminary study demonstrates that the encapsulated artificial hair cell flow sensor is capable of sensing changes in flow through a mechanoelectrical response and that its sensing capabilities may be altered by varying its surface morphology.

  4. Metabolically engineered methylotrophic yeast cells and enzymes as sensor biorecognition elements.

    PubMed

    Gonchar, Mykhailo; Maidan, Mykola; Korpan, Yaroslav; Sibirny, Volodymyr; Kotylak, Zbigniew; Sibirny, Andrei

    2002-08-01

    An extended definition of the term metabolic engineering is given and its successful use in the construction of biorecognition elements of sensors is demonstrated. It is shown that genetic and chemical modifications of methylotrophic yeast cells provide directed changes in their physiological responses towards methanol, ethanol and formaldehyde resulting in enhanced selectivity and shorter time response of the corresponding potentiometric and amperometric biosensors.

  5. Ultrasensitive detection of microbial cells using magnetic focus enhanced lateral flow sensors.

    PubMed

    Ren, Wen; Cho, Il-Hoon; Zhou, Zhongwu; Irudayaraj, Joseph

    2016-04-07

    We report on an improved lateral flow immunoassay (LFIA) sensor with a magnetic focus for ultrasensitive naked-eye detection of pathogenic microorganisms at a near single cell limit without any pre-enrichment steps, by allowing the magnetic probes to focus the labelled pathogens to the target zone of the LF strip.

  6. Construction, imaging and analysis of FRET-based tension sensors in living cells

    PubMed Central

    LaCroix, Andrew S.; Rothenberg, Katheryn E.; Berginski, Matthew E.; Urs, Aarti N.; Hoffman, Brenton D.

    2015-01-01

    Due to an increased appreciation for the importance of mechanical stimuli in many biological contexts, an interest in measuring the forces experienced by specific proteins in living cells has recently emerged. The development and use of Forster resonance energy transfer (FRET)-based molecular tension sensors has enabled these types of studies and led to important insights into the mechanisms those cells utilize to probe and respond to the mechanical nature of their surrounding environment. The process for creating and utilizing FRET-based tension sensors can be divided into three main parts: construction, imaging, and analysis. First we review several methods for the construction of genetically encoded FRET-based tension sensors, including restriction enzyme-based methods as well as the more recently developed overlap extension or Gibson Assembly protocols. Next, we discuss the intricacies associated with imaging tension sensors, including optimizing imaging parameters as well as common techniques for estimating artifacts within standard imaging systems. Then, we detail the analysis of such data and describe how to extract useful information from a FRET experiment. Finally, we provide a discussion on identifying and correcting common artifacts in the imaging of FRET-based tension sensors. PMID:25640429

  7. Construction, imaging, and analysis of FRET-based tension sensors in living cells.

    PubMed

    LaCroix, Andrew S; Rothenberg, Katheryn E; Berginski, Matthew E; Urs, Aarti N; Hoffman, Brenton D

    2015-01-01

    Due to an increased appreciation for the importance of mechanical stimuli in many biological contexts, an interest in measuring the forces experienced by specific proteins in living cells has recently emerged. The development and use of Förster resonance energy transfer (FRET)-based molecular tension sensors has enabled these types of studies and led to important insights into the mechanisms those cells utilize to probe and respond to the mechanical nature of their surrounding environment. The process for creating and utilizing FRET-based tension sensors can be divided into three main parts: construction, imaging, and analysis. First we review several methods for the construction of genetically encoded FRET-based tension sensors, including restriction enzyme-based methods as well as the more recently developed overlap extension or Gibson Assembly protocols. Next, we discuss the intricacies associated with imaging tension sensors, including optimizing imaging parameters as well as common techniques for estimating artifacts within standard imaging systems. Then, we detail the analysis of such data and describe how to extract useful information from a FRET experiment. Finally, we provide a discussion on identifying and correcting common artifacts in the imaging of FRET-based tension sensors.

  8. Refractive index fiber sensor based on Brillouin fast light

    NASA Astrophysics Data System (ADS)

    Chen, Jiali; Gan, Jiulin; Zhang, Zhishen; Yang, Tong; Deng, Huaqiu; Yang, Zhongmin

    2014-01-01

    A new type of refractive index fiber sensor was invented by combining the evanescent-field scattering sensing mechanism with the Brillouin fast light scheme. Superluminal light was realized using Brillouin lasing oscillation in a fiber ring cavity. The refractive index of the solution around the microfiber within the cavity is related to the group velocity of the fast light. This fast light refractive index sensor offers an alternative for high-accuracy sensing applications.

  9. Design and Operation of an Electrochemical Methanol Concentration Sensor for Direct Methanol Fuel Cell Systems

    NASA Technical Reports Server (NTRS)

    Narayanan, S. R.; Valdez, T. I.; Chun, W.

    2000-01-01

    The development of a 150-Watt packaged power source based on liquid feed direct methanol fuel cells is being pursued currently at the Jet propulsion Laboratory for defense applications. In our studies we find that the concentration of methanol in the fuel circulation loop affects the electrical performance and efficiency the direct methanol fuel cell systems significantly. The practical operation of direct methanol fuel cell systems, therefore, requires accurate monitoring and control of methanol concentration. The present paper reports on the principle and demonstration of an in-house developed electrochemical sensor suitable for direct methanol fuel cell systems.

  10. From Conscious Experience to Memory Storage and Retrieval:. the Role of Quantum Brain Dynamics and Boson Condensation of Evanescent Photons

    NASA Astrophysics Data System (ADS)

    Jibu, Mari; Pribram, Karl H.; Yasue, Kunio

    A quantum field theoretical formulation of an interaction between the radiation field and the electric dipole field of intracellular and extracellular water in perimembranous dendritic compartments is proposed. The intercellular spaces filled mostly with water are shown to be not just a filler but a proper substrate for dendritic processing composed of a boson condensation of evanescent photons. Macroscopic ordered dynamics of the electric dipoles of water in the perimembranous region immediately adjacent to dendritic membranes provides interactions with the radiation field to produce evanescent photons that ensure that the critical temperature of the boson condensation can be higher than the body temperature. Thus, superconducting phenomena can take place. Such a high-temperature boson condensate of evanescent photons can be understood as a physical substrate for distributed saltatory processing in dendritic arborizations. Memory storage can be understood in terms of processing involving the ionic coating of the dynamically ordered structure of water facilitated by the boson condensate of evanescent photons.

  11. Detecting DNA in Eukaryotic Cells Using an Integrated Microfluidics Electronic Sensor

    NASA Astrophysics Data System (ADS)

    Sohn, L. L.; Saleh, O. A.; Facer, G. R.; Carbeck, J. D.; Beavis, A.; Notterman, D. A.

    2000-03-01

    We have developed an integrated electronic sensor fabricated on a microfluidic chip which can measure the dielectric properties of material flowing through a micron-sized channel. We show that this sensor is advantageous over the usual optical detection techniques for microfluidics as it measures the inherent solid-state property of the analytes to be examined. In this talk, we show that we are able to not only identify small volumes of fluids but, more importantly, detect and diffentiate eukaryotic cells on the basis of DNA content.

  12. Photoacoustic evaluation of surfaces via pulsed evanescent field interaction

    NASA Astrophysics Data System (ADS)

    Goldschmidt, Benjamin S.

    In recent years, major research funding and commercial development has been going toward the production and characterization of increasingly useful nanomaterials. These materials such as quantum dots, nanoparticles, and thin lms can increase the e ciency of solar panels, create new treatments for cancer, and vastly improve the detection capabilities for various optical sensors for biosensing. Unfortunately, to date, very few methods of characterizing these types of materials exist such as scanning electron microscopy and ellipsometry. These techniques are prohibitively expensive, cannot be used with all materials, and require rigorous preparation schemes before scanning. Therefore, a new method to characterize thin lms and detect the properties of nanomaterials is needed. This study proposes a newly revived method, Total Internal Re ection Photoacoustic Spectroscopy, along with related techniques, to deliver cost e ective characterization and detection for nanomaterials and thin lms.

  13. Microfiber Optical Sensors: A Review

    PubMed Central

    Lou, Jingyi; Wang, Yipei; Tong, Limin

    2014-01-01

    With diameter close to or below the wavelength of guided light and high index contrast between the fiber core and the surrounding, an optical microfiber shows a variety of interesting waveguiding properties, including widely tailorable optical confinement, evanescent fields and waveguide dispersion. Among various microfiber applications, optical sensing has been attracting increasing research interest due to its possibilities of realizing miniaturized fiber optic sensors with small footprint, high sensitivity, fast response, high flexibility and low optical power consumption. Here we review recent progress in microfiber optical sensors regarding their fabrication, waveguide properties and sensing applications. Typical microfiber-based sensing structures, including biconical tapers, optical gratings, circular cavities, Mach-Zehnder interferometers and functionally coated/doped microfibers, are summarized. Categorized by sensing structures, microfiber optical sensors for refractive index, concentration, temperature, humidity, strain and current measurement in gas or liquid environments are reviewed. Finally, we conclude with an outlook for challenges and opportunities of microfiber optical sensors. PMID:24670720

  14. Real-time measurements of endogenous CO production from vascular cells using an ultrasensitive laser sensor

    NASA Technical Reports Server (NTRS)

    Morimoto, Y.; Durante, W.; Lancaster, D. G.; Klattenhoff, J.; Tittel, F. K.

    2001-01-01

    Carbon monoxide (CO) has been implicated as a biological messenger molecule analogous to nitric oxide. A compact gas sensor based on a midinfrared laser absorption spectroscopy was developed for direct and real-time measurement of trace levels (in approximate pmol) of CO release by vascular cells. The midinfrared light is generated by difference frequency mixing of two nearinfrared lasers in a nonlinear optical crystal. A strong infrared absorption line of CO (4.61 microm) is chosen for convenient CO detection without interference from other gas species. The generation of CO from cultured vascular smooth muscle cells was detected every 20 s without any chemical modification to the CO. The sensitivity of the sensor reached 6.9 pmol CO. CO synthesis was measured from untreated control cells (0.25 nmol per 10(7) cells/h), sodium nitroprusside-treated cells (0.29 nmol per 10(7) cells/h), and hemin-treated cells (0.49 nmol per 10(7) cells/h). The sensor also detected decreases in CO production after the addition of the heme oxygenase (HO) inhibitor tin protoporphyrin-IX (from 0.49 to 0.02 nmol per 10(7) cells/h) and increases after the administration of the HO substrate hemin (from 0.27 to 0.64 nmol per 10(7) cells/h). These results demonstrate that midinfrared laser absorption spectroscopy is a useful technique for the noninvasive and real-time detection of trace levels of CO from biological tissues.

  15. Reusable Floating-Electrode Sensor for Real-Time Electrophysiological Monitoring of Nonadherent Cells

    NASA Astrophysics Data System (ADS)

    Pham Ba, Viet Anh; Ta, Van-Thao; Park, Juhun; Park, Eun Jin; Hong, Seunghun

    2015-03-01

    We herein report the development of a reusable floating-electrode sensor (FES) based on aligned single-walled carbon nanotubes, which allowed quantitatively monitoring the electrophysiological responses from nonadherent cells. The FES was used to measure the real-time responses of normal lung cells and small-cell lung cancer (SCLC) cells to the addition of nicotine. The SCLC cells exhibited rather large electrophysiological responses to nicotine compared to normal cells, which was attributed to the overexpressed nicotinic acetylcholine receptors (nAChRs) in the SCLC cells. Importantly, using only a single device could measure repeatedly the responses of multiple individual cells to various drugs, enabling statistically meaningful measurements without errors from the device-to-device variations of the sensor characteristics. As results, that the treatment with drugs such as genistin or daidzein reduced Ca2+ influx in SCLC cells was found. Moreover, tamoxifen, has been known as an anti-estrogen compound, was found to only partly block the binding of daidzein to nAChRs. Our FES can be a promising tool for various biomedical applications such as drug screening and therapy monitoring.

  16. Planar optical waveguide based sandwich assay sensors and processes for the detection of biological targets including early detection of cancers

    DOEpatents

    Martinez, Jennifer S.; Swanson, Basil I.; Shively, John E.; Li, Lin

    2009-06-02

    An assay element is described including recognition ligands adapted for binding to carcinoembryonic antigen (CEA) bound to a film on a single mode planar optical waveguide, the film from the group of a membrane, a polymerized bilayer membrane, and a self-assembled monolayer containing polyethylene glycol or polypropylene glycol groups therein and an assay process for detecting the presence of CEA is described including injecting a possible CEA-containing sample into a sensor cell including the assay element, maintaining the sample within the sensor cell for time sufficient for binding to occur between CEA present within the sample and the recognition ligands, injecting a solution including a reporter ligand into the sensor cell; and, interrogating the sample within the sensor cell with excitation light from the waveguide, the excitation light provided by an evanescent field of the single mode penetrating into the biological target-containing sample to a distance of less than about 200 nanometers from the waveguide thereby exciting any bound reporter ligand within a distance of less than about 200 nanometers from the waveguide and resulting in a detectable signal.

  17. Powering a wireless temperature sensor using sediment microbial fuel cells with vertical arrangement of electrodes

    NASA Astrophysics Data System (ADS)

    Zhang, Fei; Tian, Lei; He, Zhen

    The application of wireless sensors is an important approach for monitoring natural water systems in remote locations; however, limited power sources are a key challenge for successful application of these sensors. Sediment microbial fuel cells (SMFCs) have shown potential as a sustainable power source with low maintenance requirements to power wireless sensors. This study examines electricity generation in lab-scale SMFCs with the sediment from Lake Michigan. Two SMFCs are operated in parallel with a difference in cathode arrangement (floating cathode vs. bottom cathode). The data show that the SMFC with a floating cathode produces more electricity and results in a shorter charging time when an ultracapacitor is connected to the circuit. To control electricity delivery and voltage elevation to a value that can drive a wireless temperature sensor, a power management system (PMS) is developed. With the PMS, both SMFCs can consistently power the wireless temperature sensor for data transmission to a computer, although the number of recorded data within the same period differs. This research provides an effective PMS for power control and valuable experience in SMFC configurations for the next onsite test of the developed SMFCs in Lake Michigan.

  18. Distributed multiple-anodes benthic microbial fuel cell as reliable power source for subsea sensors

    NASA Astrophysics Data System (ADS)

    Liu, Bingchuan; Weinstein, Alyssa; Kolln, Michael; Garrett, Caleb; Wang, Lei; Bagtzoglou, Amvrossios; Karra, Udayarka; Li, Yan; Li, Baikun

    2015-07-01

    A new type distributed benthic microbial fuel cell (MFC) (DBMFC) consisting of 18 MFC arrays was developed to enhance the robustness and stability of the power source for subsea sensor networks. A power management system (PMS) was integrated into the DBMFC system to boost the power output for two temperature sensors. The PMS was specifically designed with 18 charge pumps capable of simultaneously harvesting energy from 6 MFC units (18 anodes total) in the DBMFC system. The pilot scale DBMFC (total sediment volume: 1 m3) with continuous ocean water supply showed that the power outputs of individual MFC units were affected by the organic carbon and nitrogen contents in the sediment pore water. The MFC units with higher power output resulted in faster charging/discharging rate of the PMS supercapacitor. Manual disconnection of anodes from the PMS was conducted to simulate the anode malfunction caused by bioturbation. Fewer functional anodes (e.g. 12 out of 18 anodes were disconnected) slowed the charging/discharging rate of the PMS supercapacitor but still supported the PMS to regularly power two sensors. This scale-up DBMFC/PMS/sensor study demonstrated that multiple MFC units with multiple PMS substantially enhanced the stability and robustness of power supply to subsea sensors.

  19. Signatures of evanescent transport in ballistic suspended graphene-superconductor junctions

    PubMed Central

    Kumaravadivel, Piranavan; Du, Xu

    2016-01-01

    In Dirac materials, the low energy excitations behave like ultra-relativistic massless particles with linear energy dispersion. A particularly intriguing phenomenon arises with the intrinsic charge transport behavior at the Dirac point where the charge density approaches zero. In graphene, a 2-D Dirac fermion gas system, it was predicted that charge transport near the Dirac point is carried by evanescent modes, resulting in unconventional “pseudo-diffusive” charge transport even in the absence of disorder. In the past decade, experimental observation of this phenomenon remained challenging due to the presence of strong disorder in graphene devices which limits the accessibility of the low carrier density regime close enough to the Dirac point. Here we report transport measurements on ballistic suspended graphene-Niobium Josephson weak links that demonstrate a transition from ballistic to pseudo-diffusive like evanescent transport below a carrier density of ~1010 cm−2. Approaching the Dirac point, the sub-harmonic gap structures due to multiple Andreev reflections display a strong Fermi energy-dependence and become increasingly pronounced, while the normalized excess current through the superconductor-graphene interface decreases sharply. Our observations are in qualitative agreement with the long standing theoretical prediction for the emergence of evanescent transport mediated pseudo-diffusive transport in graphene. PMID:27080733

  20. Circular synthetic aperture sonar imaging of simple objects illuminated by an evanescent wavefield.

    PubMed

    Plotnick, Daniel S; Marston, Timothy M; Marston, Philip L

    2016-10-01

    This paper is motivated by the case where an underwater object located within the sediment is illuminated by a grazing acoustic beam below the critical angle. The included experimental work uses a liquid-liquid interface and vertically inverted geometry as a stand-in for the water-sediment boundary. In the super-critical regime sound in the water column refracts into the sediment before scattering. However, for sub-critical illumination a rapidly decaying evanescent wavefield is generated in the sediment near the water-sediment interface. For compact objects located in the sediment near the interface this can result in strong backscattering signals suitable for acoustic image reconstruction using synthetic aperture sonar techniques. Certain properties of the evanescent wavefield such as the vertical phase-locking behavior, the rapid amplitude decay with distance from the interface, and the low-pass filter effect have understandable ramifications for the image formation process and for characteristics of the reconstructed image. In particular, circular imaging techniques require correct placement of the imaging plane to properly focus an object; however, for backscattering (monostatic) evanescent image formation the imaging plane may be placed at the interface and the target will remain in focus regardless of burial depth. A laboratory experiment using simple scatterers is presented.

  1. Comments on Musha's theorem that an evanescent photon in the microtubule is a superluminal particle.

    PubMed

    Hari, Syamala D

    2014-07-01

    Takaaki Musha's research of high performance quantum computation in living systems is motivated by the theories of Penrose and Hameroff that microtubules in the brain function as quantum computers, and by those of Jibu and Yasue that the quantum states of microtubules depend upon boson condensates of evanescent photons. His work is based on the assumption that the evanescent photons described by Jibu et al. are superluminal and that they are tachyons defined and discussed by well-known physicists such as Sudarshan, Feinberg and Recami. Musha gives a brief justification for the assumption and sometimes calls it a theorem. However, the assumption is not valid because Jibu et al. stated that the evanescent photons have transmission speed smaller than that of light and that their mass is real and momentum is imaginary whereas a tachyon's mass is imaginary and momentum is real. We show here that Musha's proof of the "theorem" has errors and hence his theorem/assumption is not valid. This article is not meant to further discuss any biological aspects of the brain but only to comment on the consistency of the quantum-physical aspects of earlier work by Musha et al.

  2. Signatures of evanescent transport in ballistic suspended graphene-superconductor junctions

    NASA Astrophysics Data System (ADS)

    Kumaravadivel, Piranavan; Du, Xu

    2016-04-01

    In Dirac materials, the low energy excitations behave like ultra-relativistic massless particles with linear energy dispersion. A particularly intriguing phenomenon arises with the intrinsic charge transport behavior at the Dirac point where the charge density approaches zero. In graphene, a 2-D Dirac fermion gas system, it was predicted that charge transport near the Dirac point is carried by evanescent modes, resulting in unconventional “pseudo-diffusive” charge transport even in the absence of disorder. In the past decade, experimental observation of this phenomenon remained challenging due to the presence of strong disorder in graphene devices which limits the accessibility of the low carrier density regime close enough to the Dirac point. Here we report transport measurements on ballistic suspended graphene-Niobium Josephson weak links that demonstrate a transition from ballistic to pseudo-diffusive like evanescent transport below a carrier density of ~1010 cm‑2. Approaching the Dirac point, the sub-harmonic gap structures due to multiple Andreev reflections display a strong Fermi energy-dependence and become increasingly pronounced, while the normalized excess current through the superconductor-graphene interface decreases sharply. Our observations are in qualitative agreement with the long standing theoretical prediction for the emergence of evanescent transport mediated pseudo-diffusive transport in graphene.

  3. Polarization characteristics of Whispering-Gallery-Mode fiber lasers based on evanescent-wave-coupled gain.

    PubMed

    Zhang, Yuan-Xian; Pu, Xiao-Yun; Feng, Li; Han, De-Yu; Ren, Yi-Tao

    2013-05-20

    The polarization characteristics of Whispering-Gallery-Mode (WGM) fiber lasers based on evanescent-wave-coupled gain are investigated. For the laser gain is excited by side-pumping scheme, it is found that the polarization property of lasing emission is simply dependent on the polarized states of the pump beams. The polarization property of lasing emission depends on the propagating situation of the pump beams in an optical fiber if the laser gain is excited by evanescent-wave pumping scheme, that is, if the pump beams within the fiber are meridional beams, the lasing emission is a transverse electric (TE) wave that forms a special radial polarization emission. However, if the pump beams within the fiber are skew beams, both transverse magnetic (TM) and TE waves exist simultaneously in lasing emission that forms a special axially and radially mixed polarization emission. Pumped by skew beams, the wave-number differences between TE and TM waves are also investigated quantitatively, the results demonstrate that the wave-number difference decreases with the increase of the fiber diameter and the refractive index (RI) of the cladding solution. The observed polarization characteristics have been well explained based on lasing radiation mechanism of WGM fiber laser of gain coupled by evanescent wave.

  4. Evanescent Effects can Alter Ultraviolet Divergences in Quantum Gravity without Physical Consequences.

    PubMed

    Bern, Zvi; Cheung, Clifford; Chi, Huan-Hang; Davies, Scott; Dixon, Lance; Nohle, Josh

    2015-11-20

    Evanescent operators such as the Gauss-Bonnet term have vanishing perturbative matrix elements in exactly D=4 dimensions. Similarly, evanescent fields do not propagate in D=4; a three-form field is in this class, since it is dual to a cosmological-constant contribution. In this Letter, we show that evanescent operators and fields modify the leading ultraviolet divergence in pure gravity. To analyze the divergence, we compute the two-loop identical-helicity four-graviton amplitude and determine the coefficient of the associated (nonevanescent) R^{3} counterterm studied long ago by Goroff and Sagnotti. We compare two pairs of theories that are dual in D=4: gravity coupled to nothing or to three-form matter, and gravity coupled to zero-form or to two-form matter. Duff and van Nieuwenhuizen showed that, curiously, the one-loop trace anomaly-the coefficient of the Gauss-Bonnet operator-changes under p-form duality transformations. We concur and also find that the leading R^{3} divergence changes under duality transformations. Nevertheless, in both cases, the physical renormalized two-loop identical-helicity four-graviton amplitude can be chosen to respect duality. In particular, its renormalization-scale dependence is unaltered.

  5. A scalable pathway to nanostructured sapphire optical fiber for evanescent-field sensing and beyond

    NASA Astrophysics Data System (ADS)

    Chen, Hui; Tian, Fei; Kanka, Jiri; Du, Henry

    2015-03-01

    We here report an innovative and scalable strategy of transforming a commercial unclad sapphire optical fiber to an all-alumina nanostructured sapphire optical fiber (NSOF). The strategy entails fiber coating with metal aluminum followed by anodization to form alumina cladding of highly organized pore channel structure. Through experiments and numerical simulation, we demonstrate the utility and benefit of NSOF, analogous to all-silica microstructured optical fiber, for evanescent-field surface-enhanced Raman scattering (SERS) measurements. We experimentally reveal the feasibility of Ag nanoparticles (NPs)-enabled NSOF SERS sensing of 10-6 M Rhodamine 6G (R6G) after thermal treatment at 500 °C for 6 h by taking advantage of porous anodic aluminum oxide (AAO) structure to stabilize the Ag NPs. We show, via numerical simulations, that AAO cladding significantly increases the evanescent-field overlap, lower porosity of AAO results in higher evanescent-field overlap, and optimized AAO nanostructure yields greater SERS enhancement.

  6. A radiation-hardened two transistor memory cell for monolithic active pixel sensors in STAR experiment

    NASA Astrophysics Data System (ADS)

    Wei, X.; Gao, D.; Dorokhov, A.; Hu, Y.

    2011-01-01

    Radiation tolerance of Monolithic Active Pixel Sensors (MAPS) is dramatically decreased when intellectual property (IP) memories are integrated for fast readout application. This paper presents a new solution to improve radiation hardness and avoid latch-up for memory cell design. The tradeoffs among radiation tolerance, area and speed are significantly considered and analyzed. The cell designed in 0.35 μm process satisfies the radiation tolerance requirements of STAR experiment. The cell size is 4.55 × 5.45 μm2. This cell is smaller than the IP memory cell based on the same process and is only 26% of a radiation tolerant 6T SRAM cell used in previous contribution. The write access time of the cell is less than 2 ns, while the read access time is 80 ns.

  7. Real-time Bacterial Detection by Single Cell Based Sensors UsingSynchrotron FTIR Spectromicroscopy

    SciTech Connect

    Veiseh, Mandana; Veiseh, Omid; Martin, Michael C.; Bertozzi,Carolyn; Zhang, Miqin

    2005-08-10

    Microarrays of single macrophage cell based sensors weredeveloped and demonstrated for real time bacterium detection bysynchrotron FTIR microscopy. The cells were patterned on gold-SiO2substrates via a surface engineering technique by which the goldelectrodes were immobilized with fibronectin to mediate cell adhesion andthe silicon oxide background were passivated with PEG to resist proteinadsorption and cell adhesion. Cellular morphology and IR spectra ofsingle, double, and triple cells on gold electrodes exposed tolipopolysaccharide (LPS) of different concentrations were compared toreveal the detection capabilities of these biosensors. The single-cellbased sensors were found to generate the most significant IR wave numbervariation and thus provide the highest detection sensitivity. Changes inmorphology and IR spectrum for single cells exposed to LPS were found tobe time- and concentration-dependent and correlated with each other verywell. FTIR spectra from single cell arrays of gold electrodes withsurface area of 25 mu-m2, 100 mu-m2, and 400 mu-m2 were acquired usingboth synchrotron and conventional FTIR spectromicroscopes to study thesensitivity of detection. The results indicated that the developedsingle-cell platform can be used with conventional FTIRspectromicroscopy. This technique provides real-time, label-free, andrapid bacterial detection, and may allow for statistic and highthroughput analyses, and portability.

  8. Soluble adenylyl cyclase is an acid-base sensor in epithelial base-secreting cells.

    PubMed

    Roa, Jinae N; Tresguerres, Martin

    2016-08-01

    Blood acid-base regulation by specialized epithelia, such as gills and kidney, requires the ability to sense blood acid-base status. Here, we developed primary cultures of ray (Urolophus halleri) gill cells to study mechanisms for acid-base sensing without the interference of whole animal hormonal regulation. Ray gills have abundant base-secreting cells, identified by their noticeable expression of vacuolar-type H(+)-ATPase (VHA), and also express the evolutionarily conserved acid-base sensor soluble adenylyl cyclase (sAC). Exposure of cultured cells to extracellular alkalosis (pH 8.0, 40 mM HCO3 (-)) triggered VHA translocation to the cell membrane, similar to previous reports in live animals experiencing blood alkalosis. VHA translocation was dependent on sAC, as it was blocked by the sAC-specific inhibitor KH7. Ray gill base-secreting cells also express transmembrane adenylyl cyclases (tmACs); however, tmAC inhibition by 2',5'-dideoxyadenosine did not prevent alkalosis-dependent VHA translocation, and tmAC activation by forskolin reduced the abundance of VHA at the cell membrane. This study demonstrates that sAC is a necessary and sufficient sensor of extracellular alkalosis in ray gill base-secreting cells. In addition, this study indicates that different sources of cAMP differentially modulate cell biology.

  9. AMP-activated protein kinase—an energy sensor that regulates all aspects of cell function

    PubMed Central

    Hardie, D. Grahame

    2011-01-01

    AMP-activated protein kinase (AMPK) is a sensor of energy status that maintains cellular energy homeostasis. It arose very early during eukaryotic evolution, and its ancestral role may have been in the response to starvation. Recent work shows that the kinase is activated by increases not only in AMP, but also in ADP. Although best known for its effects on metabolism, AMPK has many other functions, including regulation of mitochondrial biogenesis and disposal, autophagy, cell polarity, and cell growth and proliferation. Both tumor cells and viruses establish mechanisms to down-regulate AMPK, allowing them to escape its restraining influences on growth. PMID:21937710

  10. A Terrestrial Microbial Fuel Cell for Powering a Single-Hop Wireless Sensor Network.

    PubMed

    Zhang, Daxing; Zhu, Yingmin; Pedrycz, Witold; Guo, Yongxian

    2016-05-18

    Microbial fuel cells (MFCs) are envisioned as one of the most promising alternative renewable energy sources because they can generate electric current continuously while treating waste. Terrestrial Microbial Fuel Cells (TMFCs) can be inoculated and work on the use of soil, which further extends the application areas of MFCs. Energy supply, as a primary influential factor determining the lifetime of Wireless Sensor Network (WSN) nodes, remains an open challenge in sensor networks. In theory, sensor nodes powered by MFCs have an eternal life. However, low power density and high internal resistance of MFCs are two pronounced problems in their operation. A single-hop WSN powered by a TMFC experimental setup was designed and experimented with. Power generation performance of the proposed TMFC, the relationships between the performance of the power generation and the environment temperature, the water content of the soil by weight were measured by experiments. Results show that the TMFC can achieve good power generation performance under special environmental conditions. Furthermore, the experiments with sensor data acquisition and wireless transmission of the TMFC powering WSN were carried out. We demonstrate that the obtained experimental results validate the feasibility of TMFCs powering WSNs.

  11. A Terrestrial Microbial Fuel Cell for Powering a Single-Hop Wireless Sensor Network

    PubMed Central

    Zhang, Daxing; Zhu, Yingmin; Pedrycz, Witold; Guo, Yongxian

    2016-01-01

    Microbial fuel cells (MFCs) are envisioned as one of the most promising alternative renewable energy sources because they can generate electric current continuously while treating waste. Terrestrial Microbial Fuel Cells (TMFCs) can be inoculated and work on the use of soil, which further extends the application areas of MFCs. Energy supply, as a primary influential factor determining the lifetime of Wireless Sensor Network (WSN) nodes, remains an open challenge in sensor networks. In theory, sensor nodes powered by MFCs have an eternal life. However, low power density and high internal resistance of MFCs are two pronounced problems in their operation. A single-hop WSN powered by a TMFC experimental setup was designed and experimented with. Power generation performance of the proposed TMFC, the relationships between the performance of the power generation and the environment temperature, the water content of the soil by weight were measured by experiments. Results show that the TMFC can achieve good power generation performance under special environmental conditions. Furthermore, the experiments with sensor data acquisition and wireless transmission of the TMFC powering WSN were carried out. We demonstrate that the obtained experimental results validate the feasibility of TMFCs powering WSNs. PMID:27213346

  12. Enhanced Viability of Endothelial Colony Forming Cells in Fibrin Microbeads for Sensor Vascularization.

    PubMed

    Gandhi, Jarel K; Zivkovic, Lada; Fisher, John P; Yoder, Mervin C; Brey, Eric M

    2015-09-18

    Enhanced vascularization at sensor interfaces can improve long-term function. Fibrin, a natural polymer, has shown promise as a biomaterial for sensor coating due to its ability to sustain endothelial cell growth and promote local vascularization. However, the culture of cells, particularly endothelial cells (EC), within 3D scaffolds for more than a few days is challenging due to rapid loss of EC viability. In this manuscript, a robust method for developing fibrin microbead scaffolds for long-term culture of encapsulated ECs is described. Fibrin microbeads are formed using sodium alginate as a structural template. The size, swelling and structural properties of the microbeads were varied with needle gauge and composition and concentration of the pre-gel solution. Endothelial colony-forming cells (ECFCs) were suspended in the fibrin beads and cultured within a perfusion bioreactor system. The perfusion bioreactor enhanced ECFCs viability and genome stability in fibrin beads relative to static culture. Perfusion bioreactors enable 3D culture of ECs within fibrin beads for potential application as a sensor coating.

  13. Cell culture monitoring for drug screening and cancer research: a transparent, microfluidic, multi-sensor microsystem.

    PubMed

    Weltin, Andreas; Slotwinski, Kinga; Kieninger, Jochen; Moser, Isabella; Jobst, Gerhard; Wego, Marcus; Ehret, Ralf; Urban, Gerald A

    2014-01-07

    We present a novel, multiparametric microphysiometry system for the dynamic online monitoring of human cancer cell metabolism. The optically transparent, modular, hybrid microsystem is based on a glass chip and combines a cell cultivation chamber, microfluidics and metabolic monitoring with fully integrated chemo- and biosensors. pH and oxygen are measured in the cell culture area, and biosensors for lactate and glucose are connected downstream by microfluidics. The wafer-level fabrication features thin-film platinum and iridium oxide microelectrodes on a glass chip, microfluidics in an epoxy resist, a hybrid assembly and an on-chip reference electrode. The reliable analytical performance of the sensors in cell culture medium was demonstrated. The pH sensors exhibit a long-term stable, linear response. The oxygen sensors show a linear behaviour, which is also observed for low oxygen concentrations. Glucose and lactate measurements show a linear, long-term stable, selective and reversible behaviour in the desired range. T98G human brain cancer cells were cultivated and cell culture metabolism was measured on-chip. Stop/flow cycles were applied and extracellular acidification, respiration, glucose consumption and lactate production were quantified. Long-term metabolic rates were determined and all parameters could be measured in the outlet channel. A placement downstream of the cell cultivation area for biosensors was realised. A highly effective medium exchange and undiluted sampling from the cell culture chamber with low flow rates (2 μl min(-1)) and low volumes (15 μl per cycle) were achieved. The drug screening application was demonstrated by detecting alteration and recovery effects of cellular metabolism induced by the addition of substances to the medium.

  14. Method of detecting defects in ion exchange membranes of electrochemical cells by chemochromic sensors

    DOEpatents

    Brooker, Robert Paul; Mohajeri, Nahid

    2016-01-05

    A method of detecting defects in membranes such as ion exchange membranes of electrochemical cells. The electrochemical cell includes an assembly having an anode side and a cathode side with the ion exchange membrane in between. In a configuration step a chemochromic sensor is placed above the cathode and flow isolation hardware lateral to the ion exchange membrane which prevents a flow of hydrogen (H.sub.2) between the cathode and anode side. The anode side is exposed to a first reactant fluid including hydrogen. The chemochromic sensor is examined after the exposing for a color change. A color change evidences the ion exchange membrane has at least one defect that permits H.sub.2 transmission therethrough.

  15. Photocatalytically Renewable Micro-electrochemical Sensor for Real-Time Monitoring of Cells.

    PubMed

    Xu, Jia-Quan; Liu, Yan-Ling; Wang, Qian; Duo, Huan-Huan; Zhang, Xin-Wei; Li, Yu-Tao; Huang, Wei-Hua

    2015-11-23

    Electrode fouling and passivation is a substantial and inevitable limitation in electrochemical biosensing, and it is a great challenge to efficiently remove the contaminant without changing the surface structure and electrochemical performance. Herein, we propose a versatile and efficient strategy based on photocatalytic cleaning to construct renewable electrochemical sensors for cell analysis. This kind of sensor was fabricated by controllable assembly of reduced graphene oxide (RGO) and TiO2 to form a sandwiching RGO@TiO2 structure, followed by deposition of Au nanoparticles (NPs) onto the RGO shell. The Au NPs-RGO composite shell provides high electrochemical performance. Meanwhile, the encapsulated TiO2 ensures an excellent photocatalytic cleaning property. Application of this renewable microsensor for detection of nitric oxide (NO) release from cells demonstrates the great potential of this strategy in electrode regeneration and biosensing.

  16. Protein-specific localization of a rhodamine-based calcium-sensor in living cells.

    PubMed

    Best, Marcel; Porth, Isabel; Hauke, Sebastian; Braun, Felix; Herten, Dirk-Peter; Wombacher, Richard

    2016-06-28

    A small synthetic calcium sensor that can be site-specifically coupled to proteins in living cells by utilizing the bio-orthogonal HaloTag labeling strategy is presented. We synthesized an iodo-derivatized BAPTA chelator with a tetramethyl rhodamine fluorophore that allows further modification by Sonogashira cross-coupling. The presented calcium sensitive dye shows a 200-fold increase in fluorescence upon calcium binding. The derivatization with an aliphatic linker bearing a terminal haloalkane-function by Sonogashira cross-coupling allows the localization of the calcium sensor to Halo fusion proteins which we successfully demonstrate in in vitro and in vivo experiments. The herein reported highly sensitive tetramethyl rhodamine based calcium indicator, which can be selectively localized to proteins, is a powerful tool to determine changes in calcium levels inside living cells with spatiotemporal resolution.

  17. A smart sensor architecture based on emergent computation in an array of outer-totalistic cells

    NASA Astrophysics Data System (ADS)

    Dogaru, Radu; Dogaru, Ioana; Glesner, Manfred

    2005-06-01

    A novel smart-sensor architecture is proposed, capable to segment and recognize characters in a monochrome image. It is capable to provide a list of ASCII codes representing the recognized characters from the monochrome visual field. It can operate as a blind's aid or for industrial applications. A bio-inspired cellular model with simple linear neurons was found the best to perform the nontrivial task of cropping isolated compact objects such as handwritten digits or characters. By attaching a simple outer-totalistic cell to each pixel sensor, emergent computation in the resulting cellular automata lattice provides a straightforward and compact solution to the otherwise computationally intensive problem of character segmentation. A simple and robust recognition algorithm is built in a compact sequential controller accessing the array of cells so that the integrated device can provide directly a list of codes of the recognized characters. Preliminary simulation tests indicate good performance and robustness to various distortions of the visual field.

  18. Thin-film spectroscopic sensor

    DOEpatents

    Burgess, Jr., Lloyd W.; Goldman, Don S.

    1992-01-01

    There is disclosed an integrated spectrometer for chemical analysis by evanescent electromagnetic radiation absorption in a reaction volume. The spectrometer comprises a noninteractive waveguide, a substrate, an entrance grating and an exit grating, an electromagnetic radiation source, and an electromagnetic radiation sensing device. There is further disclosed a chemical sensor to determine the pressure and concentration of a chemical species in a mixture comprising an interactive waveguide, a substrate, an entrance grating and an exit grating, an electromagnetic radiation source, and an electromagnetic radiation sensing device.

  19. Bioanalytical and chemical sensors using living taste, olfactory, and neural cells and tissues: a short review.

    PubMed

    Wu, Chunsheng; Lillehoj, Peter B; Wang, Ping

    2015-11-07

    Biosensors utilizing living tissues and cells have recently gained significant attention as functional devices for chemical sensing and biochemical analysis. These devices integrate biological components (i.e. single cells, cell networks, tissues) with micro-electro-mechanical systems (MEMS)-based sensors and transducers. Various types of cells and tissues derived from natural and bioengineered sources have been used as recognition and sensing elements, which are generally characterized by high sensitivity and specificity. This review summarizes the state of the art in tissue- and cell-based biosensing platforms with an emphasis on those using taste, olfactory, and neural cells and tissues. Many of these devices employ unique integration strategies and sensing schemes based on sensitive transducers including microelectrode arrays (MEAs), field effect transistors (FETs), and light-addressable potentiometric sensors (LAPSs). Several groups have coupled these hybrid biosensors with microfluidics which offers added benefits of small sample volumes and enhanced automation. While this technology is currently limited to lab settings due to the limited stability of living biological components, further research to enhance their robustness will enable these devices to be employed in field and clinical settings.

  20. Mechanical dynamics in live cells and fluorescence-based force/tension sensors.

    PubMed

    Yang, Chao; Zhang, Xiaohan; Guo, Yichen; Meng, Fanjie; Sachs, Frederick; Guo, Jun

    2015-08-01

    Three signaling systems play the fundamental roles in modulating cell activities: chemical, electrical, and mechanical. While the former two are well studied, the mechanical signaling system is still elusive because of the lack of methods to measure structural forces in real time at cellular and subcellular levels. Indeed, almost all biological processes are responsive to modulation by mechanical forces that trigger dispersive downstream electrical and biochemical pathways. Communication among the three systems is essential to make cells and tissues receptive to environmental changes. Cells have evolved many sophisticated mechanisms for the generation, perception and transduction of mechanical forces, including motor proteins and mechanosensors. In this review, we introduce some background information about mechanical dynamics in live cells, including the ubiquitous mechanical activity, various types of mechanical stimuli exerted on cells and the different mechanosensors. We also summarize recent results obtained using genetically encoded FRET (fluorescence resonance energy transfer)-based force/tension sensors; a new technique used to measure mechanical forces in structural proteins. The sensors have been incorporated into many specific structural proteins and have measured the force gradients in real time within live cells, tissues, and animals.

  1. Simultaneous Live Cell Imaging Using Dual FRET Sensors with a Single Excitation Light

    PubMed Central

    Niino, Yusuke; Hotta, Kohji; Oka, Kotaro

    2009-01-01

    Fluorescence resonance energy transfer (FRET) between fluorescent proteins is a powerful tool for visualization of signal transduction in living cells, and recently, some strategies for imaging of dual FRET pairs in a single cell have been reported. However, these necessitate alteration of excitation light between two different wavelengths to avoid the spectral overlap, resulting in sequential detection with a lag time. Thus, to follow fast signal dynamics or signal changes in highly motile cells, a single-excitation dual-FRET method should be required. Here we reported this by using four-color imaging with a single excitation light and subsequent linear unmixing to distinguish fluorescent proteins. We constructed new FRET sensors with Sapphire/RFP to combine with CFP/YFP, and accomplished simultaneous imaging of cAMP and cGMP in single cells. We confirmed that signal amplitude of our dual FRET measurement is comparable to of conventional single FRET measurement. Finally, we demonstrated to monitor both intracellular Ca2+ and cAMP in highly motile cardiac myocytes. To cancel out artifacts caused by the movement of the cell, this method expands the applicability of the combined use of dual FRET sensors for cell samples with high motility. PMID:19551140

  2. Mechanical dynamics in live cells and fluorescence-based force/tension sensors

    PubMed Central

    Yang, Chao; Zhang, Xiaohan; Guo, Yichen; Meng, Fanjie; Sachs, Frederick; Guo, Jun

    2016-01-01

    Three signaling systems play the fundamental roles in modulating cell activities: chemical, electrical, and mechanical. While the former two are well studied, the mechanical signaling system is still elusive because of the lack of methods to measure structural forces in real time at cellular and subcellular levels. Indeed, almost all biological processes are responsive to modulation by mechanical forces that trigger dispersive downstream electrical and biochemical pathways. Communication among the three systems is essential to make cells and tissues receptive to environmental changes. Cells have evolved many sophisticated mechanisms for the generation, perception and transduction of mechanical forces, including motor proteins and mechanosensors. In this review, we introduce some background information about mechanical dynamics in live cells, including the ubiquitous mechanical activity, various types of mechanical stimuli exerted on cells and the different mechanosensors. We also summarize recent results obtained using genetically encoded FRET (fluorescence resonance energy transfer)-based force/tension sensors; a new technique used to measure mechanical forces in structural proteins. The sensors have been incorporated into many specific structural proteins and have measured the force gradients in real time within live cells, tissues, and animals. PMID:25958335

  3. New light sensor molecules of single-cell ciliates

    NASA Astrophysics Data System (ADS)

    Tao, Nengbing; Song, Pill-Soon

    1994-05-01

    The unicellular ciliate, Stentor coeruleus, exhibits sensitive light-avoiding behavior. The photosensor stentorin showed a (M - H)- at 591.1304, which is in accord with the formula C34H23O10. Acetylated stentorin, when FAB-desorbed as (M + H)+, shows a series of ions indicating the presence of eight hydroxyl groups. Additional confirmation is a collisionally activated decomposition (CAD) spectrum of the (M + H)+ of the octaacetate. The NMR spectrum of stentorin shows characteristic signals of isopropyl groups. Similar studies indicate that photosensor blepharismin from Blepharisma japonicum is structurally different from stentorin. Time-resolved fluorescence decays indicated that a primary event occurs within a few picoseconds. The stimulus light signal absorbed/perceived by Stentor and possibly by Blepharisma, is apparently amplified by a transient calcium influx into the cell. Preliminary studies suggest that signal transduction in both organisms utilizes G-protein(s) as an initial transducer and a cGMP-phosphodiesterase as the effector system, analogous to the visual system of higher animals.

  4. Fabricated nano-fiber diameter as liquid concentration sensors

    NASA Astrophysics Data System (ADS)

    Chyad, Radhi M.; Mat Jafri, Mohd Zubir; Ibrahim, Kamarulazizi

    Nanofiber is characterized by thin, long, and very soft silica. Taper fibers are made using an easy and low cost chemical method. Etching is conducted with a HF solution to remove cladding and then a low molarity HF solution to reduce the fiber core diameter. One approach to on-line monitoring of the etching process uses spectrophotometer with a white light source. In the aforementioned technique, this method aims to determine the diameter of the reduced core and show the evolution of the two different processes from the nanofiber regime to the fixed regime in which the mode was remote from the surrounding evanescent field, intensity can propagate outside the segment fiber when the core diameter is less than 500 nm. Manufacturing technologies of nano-fiber sensors offer a number of approved properties of optical fiber sensors utilized in various sensory applications. The nano-fiber sensor is utilized to sense the difference in the concentration of D-glucose in double-distilled deionized water and to measure the refractive index (RI) of a sugar solution. Our proposed method exhibited satisfactory capability based on bimolecular interactions in the biological system. The response of the nano-fiber sensors indicates a different kind of interaction among various groups of AAs. These results can be interpreted in terms of solute-solute and solute-solvent interactions and the structure making or breaking ability of solutes in the given solution. This study utilized spectra photonics to measure the transmission of light through different concentrations of sugar solution, employing cell cumber and nano-optical fibers as sensors.

  5. Eddy current sensor for in-situ monitoring of swelling of Li-ion prismatic cells

    NASA Astrophysics Data System (ADS)

    Plotnikov, Yuri; Karp, Jason; Knobloch, Aaron; Kapusta, Chris; Lin, David

    2015-03-01

    In-situ monitoring an on-board rechargeable battery in hybrid cars can be used to ensure a long operating life of the battery and safe operation of the vehicle. Intercalations of ions in the electrode material during charge and discharge of a Lithium Ion battery cause periodic stress and strain of the electrode materials that can ultimately lead to fatigue resulting in capacity loss and potential battery failure. Currently this process is not monitored directly on the cells. This work is focused on development technologies that would quantify battery swelling and provide in-situ monitoring for onboard vehicle applications. Several rounds of tests have been performed to spatially characterize cell expansion of a 5 Ah cell with a nickel/manganese/cobalt-oxide cathode (Sanyo, Japan) used by Ford in their Fusion HEV battery pack. A collaborative team of researchers from GE and the University of Michigan has characterized the free expansion of these cells to be in the range of 100×125 microns (1% of total cell thickness) at the center point of the cell. GE proposed to use a thin eddy current (EC) coil to monitor these expansions on the cells while inside the package. The photolithography manufacturing process previously developed for EC arrays for detecting cracks in aircraft engine components was used to build test coils for gap monitoring. These sensors are thin enough to be placed safely between neighboring cells and capable of monitoring small variations in the gap between the cells. Preliminary investigations showed that these coils can be less than 100 micron thick and have sufficient sensitivity in a range from 0 to 2 mm. Laboratory tests revealed good correlation between EC and optical gap measurements in the desired range. Further technology development could lead to establishing a sensor network for a low cost solution for the in-situ monitoring of cell swelling during battery operation.

  6. Eddy current sensor for in-situ monitoring of swelling of Li-ion prismatic cells

    SciTech Connect

    Plotnikov, Yuri Karp, Jason Knobloch, Aaron Kapusta, Chris Lin, David

    2015-03-31

    In-situ monitoring an on-board rechargeable battery in hybrid cars can be used to ensure a long operating life of the battery and safe operation of the vehicle. Intercalations of ions in the electrode material during charge and discharge of a Lithium Ion battery cause periodic stress and strain of the electrode materials that can ultimately lead to fatigue resulting in capacity loss and potential battery failure. Currently this process is not monitored directly on the cells. This work is focused on development technologies that would quantify battery swelling and provide in-situ monitoring for onboard vehicle applications. Several rounds of tests have been performed to spatially characterize cell expansion of a 5 Ah cell with a nickel/manganese/cobalt-oxide cathode (Sanyo, Japan) used by Ford in their Fusion HEV battery pack. A collaborative team of researchers from GE and the University of Michigan has characterized the free expansion of these cells to be in the range of 100×125 microns (1% of total cell thickness) at the center point of the cell. GE proposed to use a thin eddy current (EC) coil to monitor these expansions on the cells while inside the package. The photolithography manufacturing process previously developed for EC arrays for detecting cracks in aircraft engine components was used to build test coils for gap monitoring. These sensors are thin enough to be placed safely between neighboring cells and capable of monitoring small variations in the gap between the cells. Preliminary investigations showed that these coils can be less than 100 micron thick and have sufficient sensitivity in a range from 0 to 2 mm. Laboratory tests revealed good correlation between EC and optical gap measurements in the desired range. Further technology development could lead to establishing a sensor network for a low cost solution for the in-situ monitoring of cell swelling during battery operation.

  7. High-throughput measurement of single-cell growth rates using serial microfluidic mass sensor arrays

    PubMed Central

    Cermak, Nathan; Olcum, Selim; Delgado, Francisco Feijó; Wasserman, Steven C.; Payer, Kristofor R.; Murakami, Mark; Knudsen, Scott M.; Kimmerling, Robert J.; Stevens, Mark M.; Kikuchi, Yuki; Sandikci, Arzu; Ogawa, Masaaki; Agache, Vincent; Baléras, François; Weinstock, David M.; Manalis, Scott R.

    2016-01-01

    Methods to rapidly assess cell growth would be useful for many applications, including drug susceptibility testing, but current technologies have limited sensitivity or throughput. Here we present an approach to precisely and rapidly measure growth rates of many individual cells simultaneously. We flow cells in suspension through a microfluidic channel with 10–12 resonant mass sensors distributed along its length, weighing each cell repeatedly over the 4–20 min it spends in the channel. Because multiple cells traverse the channel at the same time, we obtain growth rates for >60 cells/h with a resolution of 0.2 pg/h for mammalian cells and 0.02 pg/h for bacteria. We measure the growth of single lymphocytic cells, mouse and human T cells, primary human leukemia cells, yeast, Escherichia coli and Enterococcus faecalis. Our system reveals subpopulations of cells with divergent growth kinetics and enables assessment of cellular responses to antibiotics and antimicrobial peptides within minutes. PMID:27598230

  8. Final report on the application of chaos theory to an alumina sensor for aluminum reduction cells

    SciTech Connect

    Williford, R.E.; Windisch, C.F. Jr.

    1992-03-01

    Four chaos-related digital signal analysis (DSA) methods were applied to the analysis of voltage and current signals collected from aluminum electrolysis cells. Two separate data bases were analyzed: bench-scale laboratory experiments and a pilot-scale test. The objective was to assess the feasibility of using these types of data and analysis methods as the basis for a non-intrusive sensor to measure the alumina content in the electrolysis bath. This was the first time chaos theory approaches have been employed to analyze aluminum electrolysis cells.

  9. Microplates with integrated oxygen sensors for kinetic cell respiration measurement and cytotoxicity testing in primary and secondary cell lines.

    PubMed

    Deshpande, Rahul Ravi; Koch-Kirsch, Yvonne; Maas, Ruth; John, Gernot T; Krause, Christian; Heinzle, Elmar

    2005-06-01

    This paper presents a cytotoxicity and cell respiration assay that is nondestructive and kinetic. It makes use of 96-well microplates integrated with oxygen sensors. The oxygen signal monitored on-line gives an indication of the cell viability. We show its application for suspension cell lines (Chinese hamster ovary and HL60 cells) as well as adherent (Caco2 cells) and primary (rat hepatocytes) cells using well-known cytotoxic compounds (sodium azide, diclofenac, clozapine, sodium dodecyl sulfate, 2-thiouracil, tamoxifen, and tranylcypromine). The 50% lethality concentration (LC50) obtained from the assay is compared with the standard 3-(4,5-dimethylthiazol-2- yl)-2,5-diphenyl-2H-tetrazolium bromide end-point assay. The cells can be grown directly in the plates, and the assay requires no further reagents or processing. The cells can be harvested for further analysis, if required. The on-line dynamic measurement allows the calculation of LC50 as a function of exposure time. LC50 was shown to decrease with time in HL60 cells. The dynamics of this process was considerably different for the three compounds sodium dodecyl sulfate, tamoxifen, and diclofenac, indicating a large potential of application of this method for cell death studies. The assay system can be applied to almost any cell-based systems with little adaptation. The assay is robust, flexible, and applicable for medium- to high-throughput systems requiring only minimal handling and no additional agent.

  10. Optimization of a whole-cell biocatalyst by employing genetically encoded product sensors inside nanolitre reactors

    NASA Astrophysics Data System (ADS)

    Meyer, Andreas; Pellaux, René; Potot, Sébastien; Becker, Katja; Hohmann, Hans-Peter; Panke, Sven; Held, Martin

    2015-08-01

    Microcompartmentalization offers a high-throughput method for screening large numbers of biocatalysts generated from genetic libraries. Here we present a microcompartmentalization protocol for benchmarking the performance of whole-cell biocatalysts. Gel capsules served as nanolitre reactors (nLRs) for the cultivation and analysis of a library of Bacillus subtilis biocatalysts. The B. subtilis cells, which were co-confined with E. coli sensor cells inside the nLRs, converted the starting material cellobiose into the industrial product vitamin B2. Product formation triggered a sequence of reactions in the sensor cells: (1) conversion of B2 into flavin mononucleotide (FMN), (2) binding of FMN by a RNA riboswitch and (3) self-cleavage of RNA, which resulted in (4) the synthesis of a green fluorescent protein (GFP). The intensity of GFP fluorescence was then used to isolate B. subtilis variants that convert cellobiose into vitamin B2 with elevated efficiency. The underlying design principles of the assay are general and enable the development of similar protocols, which ultimately will speed up the optimization of whole-cell biocatalysts.

  11. Optofluidic restricted imaging, spectroscopy and counting of nanoparticles by evanescent wave using immiscible liquids.

    PubMed

    Liang, L; Zuo, Y F; Wu, W; Zhu, X Q; Yang, Y

    2016-08-21

    Conventional flow cytometry (FC) suffers from the diffraction limit for the detection of nanoparticles smaller than 100 nm, whereas traditional total internal reflection (TIR) microscopy can only detect few samples near the solid-liquid interface mostly in static states. Here we demonstrate a novel on-chip optofluidic technique using evanescent wave sensing for single nanoparticle real time detection by combining hydrodynamic focusing and TIR using immiscible flows. The immiscibility of the high-index sheath flow and the low-index core flow naturally generate a smooth, flat and step-index interface that is ideal for the TIR effect, whose evanescent field can penetrate the full width of the core flow. Hydrodynamic focusing can focus on all the nanoparticles in the extreme centre of the core flow with a width smaller than 1 μm. This technique enables us to illuminate every single sample in the running core flow by the evanescent field, leaving none unaffected. Moreover, it works well for samples much smaller than the diffraction limit. We have successfully demonstrated the scattering imaging and counting of 50 nm and 100 nm Au nanoparticles and also the fluorescence imaging and counting of 200 nm beads. The effective counting speeds are estimated as 1500, 2300 and 2000 particles per second for the three types of nanoparticles, respectively. The optical scattering spectra were also measured to determine the size of individual Au nanoparticles. This provides a new technique to detect nanoparticles and we foresee its application in the detection of molecules for biomedical analyses.

  12. Planar optical waveguide based sandwich assay sensors and processes for the detection of biological targets including protein markers, pathogens and cellular debris

    DOEpatents

    Martinez, Jennifer S.; Swanson, Basil I.; Grace, Karen M.; Grace, Wynne K.; Shreve, Andrew P.

    2009-06-02

    An assay element is described including recognition ligands bound to a film on a single mode planar optical waveguide, the film from the group of a membrane, a polymerized bilayer membrane, and a self-assembled monolayer containing polyethylene glycol or polypropylene glycol groups therein and an assay process for detecting the presence of a biological target is described including injecting a biological target-containing sample into a sensor cell including the assay element, with the recognition ligands adapted for binding to selected biological targets, maintaining the sample within the sensor cell for time sufficient for binding to occur between selected biological targets within the sample and the recognition ligands, injecting a solution including a reporter ligand into the sensor cell; and, interrogating the sample within the sensor cell with excitation light from the waveguide, the excitation light provided by an evanescent field of the single mode penetrating into the biological target-containing sample to a distance of less than about 200 nanometers from the waveguide thereby exciting the fluorescent-label in any bound reporter ligand within a distance of less than about 200 nanometers from the waveguide and resulting in a detectable signal.

  13. Simultaneous acquisition of absorption and fluorescence spectra of strong absorbers utilizing an evanescent supercontinuum.

    PubMed

    Kiefer, Johannes

    2016-12-15

    The determination of the absorption and emission spectra of strongly absorbing molecules is challenging, and the data can be biased by self-absorption of the fluorescence signal. To overcome this problem, a total internal reflection approach is proposed. The strongly absorbing sample is placed in an evanescent field of the radiation of a supercontinuum source. The collimated reflected light encodes the absorption spectrum, and the isotropic fluorescence emission is collected in a direction perpendicular to the surface at the same time. This ensures that the emitted light has a minimum possibility of self-absorption inside the sample.

  14. Swept-Source OCT Angiography Shows Sparing of the Choriocapillaris in Multiple Evanescent White Dot Syndrome.

    PubMed

    Yannuzzi, Nicolas A; Swaminathan, Swarup S; Zheng, Fang; Miller, Andrew; Gregori, Giovanni; Davis, Janet L; Rosenfeld, Philip J

    2017-01-01

    Two women with unilateral vision loss from multiple evanescent white dot syndrome were imaged serially with swept-source optical coherence tomography (SS-OCT). En face wide-field structural images revealed peripapillary outer photoreceptor disruption better than conventional fundus autofluorescence imaging. OCT angiography (OCTA) imaging showed preservation of flow within the retinal vasculature and choriocapillaris. As OCTA imaging of the choriocapillaris continues to evolve, these images may lay the groundwork for future investigation. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:69-74.].

  15. Single-particle evanescent light scattering simulations for total internal reflection microscopy

    NASA Astrophysics Data System (ADS)

    Helden, Laurent; Eremina, Elena; Riefler, Norbert; Hertlein, Christopher; Bechinger, Clemens; Eremin, Yuri; Wriedt, Thomas

    2006-10-01

    We simulate and measure light scattering of a micrometer-sized spherical particle suspended in solution close to a glass substrate. The model, based on the discrete sources method, is developed to describe the experimental situation of total internal reflection microscopy experiments; i.e., the particle is illuminated by an evanescent light field originating from the glass-solvent interface. In contrast to the well-established assumption of a simple exponential decay of the scattering intensity with distance, we demonstrate significant deviations for a certain range of penetration depths and polarization states of the incident light.

  16. Single-particle evanescent light scattering simulations for total internal reflection microscopy.

    PubMed

    Helden, Laurent; Eremina, Elena; Riefler, Norbert; Hertlein, Christopher; Bechinger, Clemens; Eremin, Yuri; Wriedt, Thomas

    2006-10-01

    We simulate and measure light scattering of a micrometer-sized spherical particle suspended in solution close to a glass substrate. The model, based on the discrete sources method, is developed to describe the experimental situation of total internal reflection microscopy experiments; i.e., the particle is illuminated by an evanescent light field originating from the glass-solvent interface. In contrast to the well-established assumption of a simple exponential decay of the scattering intensity with distance, we demonstrate significant deviations for a certain range of penetration depths and polarization states of the incident light.

  17. Graphene mode-lockers for fiber lasers functioned with evanescent field interaction

    NASA Astrophysics Data System (ADS)

    Song, Yong-Won; Jang, Sung-Yeon; Han, Won-Suk; Bae, Mi-Kyung

    2010-02-01

    Employing graphene as an intracavity passive power modulating element, we demonstrate the efficient laser pulsation in high pulse-energy regime with evanescent field interaction between the propagating light and graphene layer. Graphene is prepared by the solution based reduction of graphene oxide, and dispersed homogeneously into the water for spray onto an all-fiber substrate, side-polished fiber. With the intracavity power up to 21.41 dBm, we ensure the robust high-energy operation without any thermal damage of graphene. Resultant output pulses have center wavelength, spectral width, and repetition rate of 1561.6 nm, 1.96 nm, and 6.99 MHz, respectively.

  18. Equivalent material modelling of sandwich beams, evanescent solutions and damping investigations

    NASA Astrophysics Data System (ADS)

    de Rijk, Sophie; Nijman, Eugene

    2016-11-01

    A novel method for representing the transverse vibrations of sandwich beams as equivalent Timoshenko beams is developed. Special attention is given to damping modelling together with the evanescent parts of the solutions to assert applicability of the approach to any boundary conditions. Shear stiffness is evaluated based on current knowledge. The latter is then used to update the reference theory for vibrations in sandwich beams. Analytical case studies are presented to show the performance and limitations of the method and compared with experimental data.

  19. Evanescent wave amplification and subwavelength imaging by ultrathin uniaxial μ-near-zero material

    SciTech Connect

    Zhao, Yan

    2014-02-15

    We demonstrate strong evanescent wave amplification by a thin slab of uniaxial μ-near-zero (UMNZ) material. It is found that while retaining the same amplification effect, the slab can be made arbitrarily thin when the negative permeability along the axis of anisotropy approaches zero. Numerical results show that using a single layer of split-ring resonators (SRRs) with its thickness equal three thousandth of the incident wavelength (λ/3000), a subwavelength source distribution with λ/4 resolution can be transferred to a distance of λ/3.

  20. Evanescent-wave coupled right angled buried waveguide: Applications in carbon nanotube mode-locking

    SciTech Connect

    Mary, R.; Thomson, R. R.; Kar, A. K.; Brown, G.; Popa, D.; Sun, Z.; Torrisi, F.; Hasan, T.; Milana, S.; Bonaccorso, F.; Ferrari, A. C.

    2013-11-25

    We present an evanescent-field device based on a right-angled waveguide. This consists of orthogonal waveguides, with their points of intersection lying along an angled facet of the chip. Light guided along one waveguide is incident at the angled dielectric-air facet at an angle exceeding the critical angle, so that the totally internally reflected light is coupled into the second waveguide. By depositing a nanotube film on the angled surface, the chip is then used to mode-lock an Erbium doped fiber ring laser with a repetition rate of 26 MHz, and pulse duration of 800 fs.

  1. Micromachined nanocalorimetric sensor for ultra-low-volume cell-based assays.

    PubMed

    Johannessen, Erik A; Weaver, John M R; Bourova, Lenka; Svoboda, Petr; Cobbold, Peter H; Cooper, Jonathan M

    2002-05-01

    Current strategies for cell-based screening generally focus on the development of highly specific assays, which require an understanding of the nature of the signaling molecules and cellular pathways involved. In contrast, changes in temperature of cells provides a measure of altered cellular metabolism that is not stimulus specific and hence could have widespread applications in cell-based screening of receptor agonists and antagonists, as well as in the assessment of toxicity of new lead compounds. Consequently, we have developed a micromachined nanocalorimetric biological sensor using a small number of isolated living cells integrated within a subnanoliter format, which is capable of detecting 13 nW of generated power from the cells, upon exposure to a chemical or pharmaceutical stimulus. The sensor comprises a 10-junction gold and nickel thermopile, integrated on a silicon chip which was back-etched to span a 800-nm-thick membrane of silicon nitride. The thin-film membrane, which supported the sensing junctions of the thermoelectric transducer, gave the system a temperature resolution of 0.125 mK, a low heat capacity of 1.2 nJ mK(-1), and a rapid (unfiltered) response time of 12 ms. The application of the system in ultra-low-volume cell-based assays could provide a rapid endogenous screen. It offers important additional advantages over existing methods in that it is generic in nature, it does not require the use of recombinant cell lines or of detailed assay development, and finally, it can enable the use of primary cell lines or tissue biopsies.

  2. Studies of Hematopoietic Cell Differentiation with a Ratiometric and Reversible Sensor of Mitochondrial Reactive Oxygen Species

    PubMed Central

    Kaur, Amandeep; Jankowska, Karolina; Pilgrim, Chelsea; Fraser, Stuart T.

    2016-01-01

    Abstract Aims: Chronic elevations in cellular redox state are known to result in the onset of various pathological conditions, but transient increases in reactive oxygen species (ROS)/reactive nitrogen species (RNS) are necessary for signal transduction and various physiological functions. There is a distinct lack of reversible fluorescent tools that can aid in studying and unraveling the roles of ROS/RNS in physiology and pathology by monitoring the variations in cellular ROS levels over time. In this work, we report the development of ratiometric fluorescent sensors that reversibly respond to changes in mitochondrial redox state. Results: Photophysical studies of the developed flavin–rhodamine redox sensors, flavin–rhodamine redox sensor 1 (FRR1) and flavin–rhodamine redox sensor 2 (FRR2), confirmed the reversible response of the probes upon reduction and re-oxidation over more than five cycles. The ratiometric output of FRR1 and FRR2 remained unaltered in the presence of other possible cellular interferants (metals and pH). Microscopy studies indicated clear mitochondrial localization of both probes, and FRR2 was shown to report the time-dependent increase of mitochondrial ROS levels after lipopolysaccharide stimulation in macrophages. Moreover, it was used to study the variations in mitochondrial redox state in mouse hematopoietic cells at different stages of embryonic development and maturation. Innovation: This study provides the first ratiometric and reversible probes for ROS, targeted to the mitochondria, which reveal variations in mitochondrial ROS levels at different stages of embryonic and adult blood cell production. Conclusions: Our results suggest that with their ratiometric and reversible outputs, FRR1 and FRR2 are valuable tools for the future study of oxidative stress and its implications in physiology and pathology. Antioxid. Redox Signal. 24, 667–679. PMID:26865422

  3. PAS kinase as a nutrient sensor in neuroblastoma and hypothalamic cells required for the normal expression and activity of other cellular nutrient and energy sensors.

    PubMed

    Hurtado-Carneiro, Verónica; Roncero, Isabel; Blazquez, Enrique; Alvarez, Elvira; Sanz, Carmen

    2013-12-01

    PAS kinase (PASK) is a nutrient sensor that is highly conserved throughout evolution. PASK-deficient mice reveal a metabolic phenotype similar to that described in S6 kinase-1 S6K1-deficient mice that are protected against obesity. Hypothalamic metabolic sensors, such as AMP-activated protein kinase (AMPK) and the mammalian target of rapamycin (mTOR), play an important role in feeding behavior, the homeostasis of body weight, and energy balance. These sensors respond to changes in nutrient levels in the hypothalamic areas involved in feeding behavior and in neuroblastoma N2A cells, and we have recently reported that those effects are modulated by the anorexigenic peptide glucagon-like peptide-1 (GLP-1). Here, we identified PASK in both N2A cells and rat VMH and LH areas and found that its expression is regulated by glucose and GLP-1. High levels of glucose decreased Pask gene expression. Furthermore, PASK-silenced N2A cells record an impaired response by the AMPK and mTOR/S6K1 pathways to changes in glucose levels. Likewise, GLP-1 effect on the activity of AMPK, S6K1, and other intermediaries of both pathways and the regulatory role at the level of gene expression were also blocked in PASK-silenced cells. The absence of response to low glucose concentrations in PASK-silenced cells correlates with increased ATP content, low expression of mRNA coding for AMPK upstream kinase LKB1, and enhanced activation of S6K1. Our findings indicate that, at least in N2A cells, PASK is a key kinase in GLP-1 actions and exerts a coordinated response with the other metabolic sensors, suggesting that PASK might play an important role in feeding behavior.

  4. Spearhead Nanometric Field-Effect Transistor Sensors for Single-Cell Analysis

    PubMed Central

    Córdoba, Ainara López; Ali, Tayyibah; Shevchuk, Andrew; Takahashi, Yasufumi; Novak, Pavel; Edwards, Christopher; Lab, Max; Gopal, Sahana; Chiappini, Ciro; Anand, Uma; Magnani, Luca; Coombes, R. Charles; Gorelik, Julia; Matsue, Tomokazu; Schuhmann, Wolfgang; Klenerman, David; Sviderskaya, Elena V.; Korchev, Yuri

    2016-01-01

    Nanometric field-effect-transistor (FET) sensors are made on the tip of spear-shaped dual carbon nanoelectrodes derived from carbon deposition inside double-barrel nanopipettes. The easy fabrication route allows deposition of semiconductors or conducting polymers to comprise the transistor channel. A channel from electrodeposited poly pyrrole (PPy) exhibits high sensitivity toward pH changes. This property is exploited by immobilizing hexokinase on PPy nano-FETs to give rise to a selective ATP biosensor. Extracellular pH and ATP gradients are key biochemical constituents in the microenvironment of living cells; we monitor their real-time changes in relation to cancer cells and cardiomyocytes. The highly localized detection is possible because of the high aspect ratio and the spear-like design of the nano-FET probes. The accurately positioned nano-FET sensors can detect concentration gradients in three-dimensional space, identify biochemical properties of a single living cell, and after cell membrane penetration perform intracellular measurements. PMID:26816294

  5. On-chip integrated lensless fluorescence microscopy/spectroscopy module for cell-based sensors

    NASA Astrophysics Data System (ADS)

    Li, Wei; Knoll, Thorsten; Sossalla, Adam; Bueth, Heiko; Thielecke, Hagen

    2011-03-01

    The integration of a fluorescence microscopy/spectroscopy module in cell-based lab-on-a-chip systems is of high interest for applications in cell-based diagnostics and substance evaluation in situ. We present an on-chip integrated lensless fluorescence imaging module applying the principle of contact/proximate optical lithography. The pixel resolution is comparable with a 4 x objective microscope. The module can be used for morphology and fluorescence imaging of mammalian cells (15 - 20 μm) as well as for testing the concentration of a fluorescent substance. The biological samples or solutions are sustained in disposable sterilized microfluidic chips with 1 μm thick silicon nitride (Si3N4) membranes. These chips are assembled on the surface of a 5 megapixel colored CMOS image sensor array with 1.75 μm pixel size, which is coated with an additional interference filter. Each culturing chip consists of a MEMS cavity chip and a PDMS microfluidic interface. The surface of the CMOS image sensor is smoothened using SU-8 photoresist spin-coating for a commercial grade interference filter (optical density >= 5) coating by Plasma-Ion Assisted Deposition thereafter. The function is demonstrated by primary imaging results of the non-/fluorescent mammalian cells/microspheres as well as by differentiating different concentrations of FITC solutions.

  6. Evaluation of the Paratrend Multi-Analyte Sensor for Potential Utilization in Long-Duration Automated Cell Culture Monitoring

    NASA Technical Reports Server (NTRS)

    Hwang, Emma Y.; Pappas, Dimitri; Jeevarajan, Antony S.; Anderson, Melody M.

    2004-01-01

    BACKGROUND: Compact and automated sensors are desired for assessing the health of cell cultures in biotechnology experiments. While several single-analyte sensors exist to measure culture health, a multi-analyte sensor would simplify the cell culture system. One such multi-analyte sensor, the Paratrend 7 manufactured by Diametrics Medical, consists of three optical fibers for measuring pH, dissolved carbon dioxide (pCO(2)), dissolved oxygen (pO(2)), and a thermocouple to measure temperature. The sensor bundle was designed for intra-vascular measurements in clinical settings, and can be used in bioreactors operated both on the ground and in NASA's Space Shuttle and International Space Station (ISS) experiments. METHODS: A Paratrend 7 sensor was placed at the outlet of a bioreactor inoculated with BHK-21 (baby hamster kidney) cells. The pH, pCO(2), pO(2), and temperature data were transferred continuously to an external computer. Cell culture medium, manually extracted from the bioreactor through a sampling port, was also assayed using a bench top blood gas analyzer (BGA). RESULTS: Two Paratrend 7 sensors were used over a single cell culture experiment (64 days). When compared to the manually obtained BGA samples, the sensor had good agreement for pH, pCO(2), and pO(2) with bias (and precision) 0.005(0.024), 8.0 mmHg (4.4 mmHg), and 11 mmHg (17 mmHg), respectively for the first two sensors. A third Paratrend sensor (operated for 141 days) had similar agreement (0.02+/-0.15 for pH, -4+/-8 mm Hg for pCO(2), and 24+/-18 mmHg for pO(2)). CONCLUSION: The resulting biases and precisions are com- parable to Paratrend sensor clinical results. Although the pO(2) differences may be acceptable for clinically relevant measurement ranges, the O(2) sensor in this bundle may not be reliable enough for the ranges of pO(2) in these cell culture studies without periodic calibration.

  7. A feasibility study of the use of bounded beams resembling the shape of evanescent and inhomogeneous waves.

    PubMed

    Declercq, Nico F; Leroy, Oswald

    2011-08-01

    Plane waves are solutions of the visco-elastic wave equation. Their wave vector can be real for homogeneous plane waves or complex for inhomogeneous and evanescent plane waves. Although interesting from a theoretical point of view, complex wave vectors normally only emerge naturally when propagation or scattering is studied of sound under the appearance of damping effects. Because of the particular behavior of inhomogeneous and evanescent waves and their estimated efficiency for surface wave generation, bounded beams, experimentally mimicking their infinite counterparts similar to (wide) Gaussian beams imitating infinite harmonic plane waves, are of special interest in this report. The study describes the behavior of bounded inhomogeneous and bounded evanescent waves in terms of amplitude and phase distribution as well as energy flow direction. The outcome is of importance to the applicability of bounded inhomogeneous ultrasonic waves for nondestructive testing.

  8. Dispersive optomechanical coupling between a SiN nanomechanical oscillator and evanescent fields of a silica optical resonator

    NASA Astrophysics Data System (ADS)

    Dong, Chunhua; Htay Oo, Thein; Fiore, Victor; Wang, Hailin

    2013-03-01

    Tensile stressed SiN nanostrings can feature a picogram effective mass and a mechanical Q-factor exceeding a million. These remarkable nanomechanical oscillators can be dispersively-coupled to an ultra-high finesse optical microresonator via its evanescent field. This composite optomechanical system can potentially lead to a cooperativity that far exceeds that of monolithic optomechanical resonators. Here, we report an experimental study coupling a SiN nanostring to evanescent fields of a whispering gallery mode (WGM) in a silica microsphere. The slight deformation of the microsphere enables us to use free-space optical excitation to probe the optomechanical coupling. The dispersive coupling between a nanostring and the evanescent field of a WGM is generally expected to lead to a red shift in the resonance frequency of the WGM. Our experiments, however, reveal a blue frequency shift of the WGM. Detailed experimental studies and possible physical mechanisms for the blue shift will be presented.

  9. Optical Characterization of Commercial Lithiated Graphite Battery Electrodes and in Situ Fiber Optic Evanescent Wave Spectroscopy.

    PubMed

    Ghannoum, AbdulRahman; Norris, Ryan C; Iyer, Krishna; Zdravkova, Liliana; Yu, Aiping; Nieva, Patricia

    2016-07-27

    Optical characterization of graphite anodes in lithium ion batteries (LIB) is presented here for potential use in estimating their state of charge (SOC). The characterization is based on reflectance spectroscopy of the anode of commercial LIB cells and in situ optical measurements using an embedded optical fiber sensor. The optical characterization of the anode using wavelengths ranging from 500 to 900 nm supports the dominance of graphite over the solid electrolyte interface in governing the anode's reflectance properties. It is demonstrated that lithiated graphite's reflectance has a significant change in the near-infrared band, 750-900 nm, compared with the visible spectrum as a function of SOC. An embedded optical sensor is used to measure the transmittance of graphite anode in the near-infrared band, and the results suggest that a unique inexpensive method may be developed to estimate the SOC of a LIB.

  10. Using graphene nano-particle embedded in photonic crystal fiber for evanescent wave mode-locking of fiber laser.

    PubMed

    Lin, Yung-Hsiang; Yang, Chun-Yu; Liou, Jia-Hong; Yu, Chin-Ping; Lin, Gong-Ru

    2013-07-15

    A photonic crystal fiber (PCF) with high-quality graphene nano-particles uniformly dispersed in the hole cladding are demonstrated to passively mode-lock the erbium-doped fiber laser (EDFL) by evanescent-wave interaction. The few-layer graphene nano-particles are obtained by a stabilized electrochemical exfoliation at a threshold bias. These slowly and softly exfoliated graphene nano-particle exhibits an intense 2D band and an almost disappeared D band in the Raman scattering spectrum. The saturable phenomena of the extinction coefficient β in the cladding provides a loss modulation for the intracavity photon intensity by the evanescent-wave interaction. The evanescent-wave mode-locking scheme effectively enlarges the interaction length of saturable absorption with graphene nano-particle to provide an increasing transmittance ΔT of 5% and modulation depth of 13%. By comparing the core-wave and evanescent-wave mode-locking under the same linear transmittance, the transmittance of the graphene nano-particles on the end-face of SMF only enlarges from 0.54 to 0.578 with ΔT = 3.8% and the modulation depth of 10.8%. The evanescent wave interaction is found to be better than the traditional approach which confines the graphene nano-particles at the interface of two SMF patchcords. When enlarging the intra-cavity gain by simultaneously increasing the pumping current of 980-nm and 1480-nm pumping laser diodes (LDs) to 900 mA, the passively mode-locked EDFL shortens its pulsewidth to 650 fs and broadens its spectral linewidth to 3.92 nm. An extremely low carrier amplitude jitter (CAJ) of 1.2-1.6% is observed to confirm the stable EDFL pulse-train with the cladding graphene nano-particle based evanescent-wave mode-locking.

  11. Impact of Substrate Bias on Fixed-Pattern-Noise in Active Pixel Sensor Cells

    NASA Astrophysics Data System (ADS)

    Terauchi, Mamoru

    2007-11-01

    The effect of substrate (body) bias on fixed-pattern-noise (FPN) in active pixel sensor (APS) cells is studied. Through measuring test devices consisting of two metal-oxide-semiconductor field-effect transistors (MOSFETs) connected in series with each of the transistors located in the same well region, it has been revealed that substrate bias, which is inevitably applied in a normal circuit configuration in conventional APS cells, worsens the characteristics fluctuation in source-follower amplifiers in APS cells, leading to FPN that cannot be mitigated by conventional correction methods such as correlated double sampling. In addition it has been confirmed that the current-voltage characteristics of logarithmic converters, each of which is realized using a MOSFET with gate and drain terminals connected together, are also affected by substrate bias, resulting in increased characteristics fluctuation as compared with the case with no substrate bias.

  12. Temperature and Humidity Sensor Powered by an Individual Microbial Fuel Cell in a Power Management System.

    PubMed

    Zheng, Qi; Xiong, Lei; Mo, Bing; Lu, Weihong; Kim, Suki; Wang, Zhenyu

    2015-09-11

    Microbial fuel cells (MFCs) are of increasing interest as bioelectrochemical systems for decomposing organic materials and converting chemical energy into electricity. The main challenge for this technology is that the low power and voltage of the devices restricts the use of MFCs in practical applications. In this paper, a power management system (PMS) is developed to store the energy and export an increased voltage. The designed PMS successfully increases the low voltage generated by an individual MFC to a high potential of 5 V, capable of driving a wireless temperature and humidity sensor based on nRF24L01 data transmission modules. With the PMS, MFCs can intermittently power the sensor for data transmission to a remote receiver. It is concluded that even an individual MFC can supply the energy required to power the sensor and telemetry system with the designed PMS. The presented PMS can be widely used for unmanned environmental monitoring such as wild rivers, lakes, and adjacent water areas, and offers promise for further advances in MFC technology.

  13. Silicon Quantum Dot-Based Fluorescence Turn-On Metal Ion Sensors in Live Cells.

    PubMed

    Dhenadhayalan, Namasivayam; Lee, Hsin-Lung; Yadav, Kanchan; Lin, King-Chuen; Lin, Yih-Tyng; Chang, A H H

    2016-09-14

    Multiple sensor systems are designed by varying aza-crown ether moiety in silicon quantum dots (SiQDs) for detecting individual Mg(2+), Ca(2+), and Mn(2+) metal ions with significant selectivity and sensitivity. The detection limit of Mg(2+), Ca(2+), and Mn(2+) can reach 1.81, 3.15, and 0.47 μM, respectively. Upon excitation of the SiQDs which are coordinated with aza-crown ethers, the photoinduced electron transfer (PET) takes place from aza-crown ether moiety to the valence band of SiQDs core such that the reduced probability of electron-hole recombination may diminish the subsequent fluorescence. The fluorescence suppression caused by such PET effect will be relieved after selective metal ion is added. The charge-electron binding force between the metal ion and aza-crown ether hinders the PET and thereby restores the fluorescence of SiQDs. The design of sensor system is based on the fluorescence "turn-on" of SiQDs while in search of the appropriate metal ion. For practical application, the sensing capabilities of metal ions in the live cells are performed and the confocal image results reveal their promising applicability as an effective and nontoxic metal ion sensor.

  14. Temperature and Humidity Sensor Powered by an Individual Microbial Fuel Cell in a Power Management System

    PubMed Central

    Zheng, Qi; Xiong, Lei; Mo, Bing; Lu, Weihong; Kim, Suki; Wang, Zhenyu

    2015-01-01

    Microbial fuel cells (MFCs) are of increasing interest as bioelectrochemical systems for decomposing organic materials and converting chemical energy into electricity. The main challenge for this technology is that the low power and voltage of the devices restricts the use of MFCs in practical applications. In this paper, a power management system (PMS) is developed to store the energy and export an increased voltage. The designed PMS successfully increases the low voltage generated by an individual MFC to a high potential of 5 V, capable of driving a wireless temperature and humidity sensor based on nRF24L01 data transmission modules. With the PMS, MFCs can intermittently power the sensor for data transmission to a remote receiver. It is concluded that even an individual MFC can supply the energy required to power the sensor and telemetry system with the designed PMS. The presented PMS can be widely used for unmanned environmental monitoring such as wild rivers, lakes, and adjacent water areas, and offers promise for further advances in MFC technology. PMID:26378546

  15. A reusable evanescent wave immunosensor for highly sensitive detection of bisphenol A in water samples

    NASA Astrophysics Data System (ADS)

    Xiao-Hong, Zhou; Lan-Hua, Liu; Wei-Qi, Xu; Bao-Dong, Song; Jian-Wu, Sheng; Miao, He; Han-Chang, Shi

    2014-04-01

    This paper proposed a compact and portable planar waveguide evanescent wave immunosensor (EWI) for highly sensitive detection of BPA. The incident light is coupled into the planar waveguide chip via a beveled angle through undergoing total internal reflection, where the evanescent wave field forms and excites the binding fluorophore-tagged antibodies on the chip surface. Typical calibration curves obtained for BPA has detection limits of 0.03 μg/L. Linear response for BPA ranged from 0.124 μg/L-9.60 μg/L with 50% inhibition concentration for BPA of 1.09 +/- 0.25 μg/L. The regeneration of the planar optical waveguide chip allows the performance of more than 300 assay cycles within an analysis time of about 20 min for each assay cycle. By application of effective pretreatment procedure, the recoveries of BPA in real water samples gave values from 88.3% +/- 8.5% to 103.7% +/- 3.5%, confirming its application potential in the measurement of BPA in reality.

  16. Experimental investigation of evanescence-based infrared biodetection technique for micro-total-analysis systems

    NASA Astrophysics Data System (ADS)

    Chandrasekaran, Arvind; Packirisamy, Muthukumaran

    2009-09-01

    The advent of microoptoelectromechanical systems (MOEMS) and its integration with other technologies such as microfluidics, microthermal, immunoproteomics, etc. has led to the concept of an integrated micro-total-analysis systems (μTAS) or Lab-on-a-Chip for chemical and biological applications. Recently, research and development of μTAS have attained a significant growth rate over several biodetection sciences, in situ medical diagnoses, and point-of-care testing applications. However, it is essential to develop suitable biophysical label-free detection methods for the success, reliability, and ease of use of the μTAS. We proposed an infrared (IR)-based evanescence wave detection system on the silicon-on-insulator platform for biodetection with μTAS. The system operates on the principle of bio-optical interaction that occurs due to the evanescence of light from the waveguide device. The feasibility of biodetection has been experimentally investigated by the detection of horse radish peroxidase upon its reaction with hydrogen peroxide.

  17. Semi-Automated, Occupationally Safe Immunofluorescence Microtip Sensor for Rapid Detection of Mycobacterium Cells in Sputum

    PubMed Central

    Soelberg, Scott D.; Weigel, Kris M.; Hiraiwa, Morgan; Cairns, Andrew; Lee, Hyun-Boo; Furlong, Clement E.; Oh, Kieseok; Lee, Kyong-Hoon; Gao, Dayong; Chung, Jae-Hyun; Cangelosi, Gerard A.

    2014-01-01

    An occupationally safe (biosafe) sputum liquefaction protocol was developed for use with a semi-automated antibody-based microtip immunofluorescence sensor. The protocol effectively liquefied sputum and inactivated microorganisms including Mycobacterium tuberculosis, while preserving the antibody-binding activity of Mycobacterium cell surface antigens. Sputum was treated with a synergistic chemical-thermal protocol that included moderate concentrations of NaOH and detergent at 60°C for 5 to 10 min. Samples spiked with M. tuberculosis complex cells showed approximately 106-fold inactivation of the pathogen after treatment. Antibody binding was retained post-treatment, as determined by analysis with a microtip immunosensor. The sensor correctly distinguished between Mycobacterium species and other cell types naturally present in biosafe-treated sputum, with a detection limit of 100 CFU/mL for M. tuberculosis, in a 30-minute sample-to-result process. The microtip device was also semi-automated and shown to be compatible with low-cost, LED-powered fluorescence microscopy. The device and biosafe sputum liquefaction method opens the door to rapid detection of tuberculosis in settings with limited laboratory infrastructure. PMID:24465845

  18. Host-cell sensors for Plasmodium activate innate immunity against liver-stage infection.

    PubMed

    Liehl, Peter; Zuzarte-Luís, Vanessa; Chan, Jennie; Zillinger, Thomas; Baptista, Fernanda; Carapau, Daniel; Konert, Madlen; Hanson, Kirsten K; Carret, Céline; Lassnig, Caroline; Müller, Mathias; Kalinke, Ulrich; Saeed, Mohsan; Chora, Angelo Ferreira; Golenbock, Douglas T; Strobl, Birgit; Prudêncio, Miguel; Coelho, Luis P; Kappe, Stefan H; Superti-Furga, Giulio; Pichlmair, Andreas; Vigário, Ana M; Rice, Charles M; Fitzgerald, Katherine A; Barchet, Winfried; Mota, Maria M

    2014-01-01

    Before they infect red blood cells and cause malaria, Plasmodium parasites undergo an obligate and clinically silent expansion phase in the liver that is supposedly undetected by the host. Here, we demonstrate the engagement of a type I interferon (IFN) response during Plasmodium replication in the liver. We identified Plasmodium RNA as a previously unrecognized pathogen-associated molecular pattern (PAMP) capable of activating a type I IFN response via the cytosolic pattern recognition receptor Mda5. This response, initiated by liver-resident cells through the adaptor molecule for cytosolic RNA sensors, Mavs, and the transcription factors Irf3 and Irf7, is propagated by hepatocytes in an interferon-α/β receptor-dependent manner. This signaling pathway is critical for immune cell-mediated host resistance to liver-stage Plasmodium infection, which we find can be primed with other PAMPs, including hepatitis C virus RNA. Together, our results show that the liver has sensor mechanisms for Plasmodium that mediate a functional antiparasite response driven by type I IFN.

  19. A new simple Schiff base fluorescence "on" sensor for Al3+ and its living cell imaging.

    PubMed

    Kumar, Jutika; Sarma, Manas Jyoti; Phukan, Prodeep; Das, Diganta Kumar

    2015-03-14

    The simple Schiff base (Z)-N-benzylidenenaphthalen-1-amine (L) acts as an effective fluorescence sensor for Al(3+) by "off-on" mode, and ca. 42 times enhancement in fluorescence intensity is observed. The detection limit of L towards Al(3+) is observed to be 5 × 10(-5) M. UV/Visible and fluorescence data as well as DFT calculations confirm 1:3 coordination between Al(3+) and L through N atoms in a pyramidal shape. L is employed for imaging the Al(3+) ion in living biological cells and for the determination of the Al(3+) ion in bovine serum albumin.

  20. Developing a cell-based sensor for the detection of Autoinducer-2

    NASA Astrophysics Data System (ADS)

    Servinsky, Matthew D.; Germane, Katherine; Gerlach, Elliot S.; Tsao, Chen-Yu; Byrd, Christopher M.; Sund, Christian J.; Bentley, William E.

    2013-05-01

    Bacteria use an intricate set of communication systems for sensing and interpreting environmental cues that coordinate population-based behavior. Quorum sensing is one of these systems, and it involves the production, release, and detection of small chemical signaling molecules. Recent research has revealed the role of quorum sensing molecules in the control of microbial activities such as biofilm formation. In this presentation we outline the development of a recombinant E. coli cell-based sensor for detection of the quorum sensing molecule Autoinducer-2 (AI-2), as well as engineering strategies to remove sugar and anoxic inhibition of the strain.

  1. Construction of a cell-based sensor for the detection of autoinducer-2

    NASA Astrophysics Data System (ADS)

    Servinsky, Matthew D.; Allen, Patrick C.; Tsao, Chen-Yu; Byrd, Christopher M.; Sund, Christian J.; Bentley, William E.

    2012-05-01

    Microbially Induced Corrosion (MIC) occurs at metal surfaces and is associated with microorganisms and their metabolic activities. These microbes can coexist as biofilms, growing as synergistic communities (consortia) that are able to affect electrochemical processes, both cathodic and anodic, often through co-operative metabolism. Recent research has revealed the role of "quorum sensing" molecules in control of microbial activities such as biofilm formation. In this paper, we propose the detection of quorum sensing molecules as a means of detecting bacterial contamination prior to the onset on biofilm formation. Further we outline the development of an E. coli cell based sensor for detection of the quorum sensing molecule Autoinducer-2 (AI-2).

  2. Optical nanosensors for chemical analysis inside single living cells. 1. Fabrication, characterization, and methods for intracellular delivery of PEBBLE sensors.

    PubMed

    Clark, H A; Hoyer, M; Philbert, M A; Kopelman, R

    1999-11-01

    Spherical optical nanosensors, or PEBBLEs (probes encapsulated by biologically localized embedding), have been produced in sizes including 20 and 200 nm in diameter. These sensors are fabricated in a microemulsion and consist of fluorescent indicators entrapped in a polyacrylamide matrix. A generalized polymerization method has been developed that permits production of sensors containing any hydrophilic dye or combination of dyes in the matrix. The PEBBLE matrix protects the fluorescent dye from interference by proteins, allowing reliable in vivo calibrations of dyes. Sensor response times are less than 1 ms. Cell viability assays indicate that the PEBBLEs are biocompatible, with negligible biological effects compared to control conditions. Several sensor delivery methods have been studied, including liposomal delivery, gene gun bombardment, and picoinjection into single living cells.

  3. YAP and TAZ in epithelial stem cells: A sensor for cell polarity, mechanical forces and tissue damage

    PubMed Central

    Elbediwy, Ahmed; Vincent‐Mistiaen, Zoé I.

    2016-01-01

    The YAP/TAZ family of transcriptional co‐activators drives cell proliferation in epithelial tissues and cancers. Yet, how YAP and TAZ are physiologically regulated remains unclear. Here we review recent reports that YAP and TAZ act primarily as sensors of epithelial cell polarity, being inhibited when cells differentiate an apical membrane domain, and being activated when cells contact the extracellular matrix via their basal membrane domain. Apical signalling occurs via the canonical Crumbs/CRB‐Hippo/MST‐Warts/LATS kinase cascade to phosphorylate and inhibit YAP/TAZ. Basal signalling occurs via Integrins and Src family kinases to phosphorylate and activate YAP/TAZ. Thus, YAP/TAZ is localised to the nucleus in basal stem/progenitor cells and cytoplasm in differentiated squamous cells or columnar cells. In addition, other signals such as mechanical forces, tissue damage and possibly receptor tyrosine kinases (RTKs) can influence MST‐LATS or Src family kinase activity to modulate YAP/TAZ activity. PMID:27173018

  4. Fabrication of thermal microphotonic sensors and sensor arrays

    SciTech Connect

    Shaw, Michael J.; Watts, Michael R.; Nielson, Gregory N.

    2010-10-26

    A thermal microphotonic sensor is fabricated on a silicon substrate by etching an opening and a trench into the substrate, and then filling in the opening and trench with silicon oxide which can be deposited or formed by thermally oxidizing a portion of the silicon substrate surrounding the opening and trench. The silicon oxide forms a support post for an optical resonator which is subsequently formed from a layer of silicon nitride, and also forms a base for an optical waveguide formed from the silicon nitride layer. Part of the silicon substrate can be selectively etched away to elevate the waveguide and resonator. The thermal microphotonic sensor, which is useful to detect infrared radiation via a change in the evanescent coupling of light between the waveguide and resonator, can be formed as a single device or as an array.

  5. Photochemical Deposition of Semiconductor Thin Films and Their Application for Solar Cells and Gas Sensors

    NASA Astrophysics Data System (ADS)

    Ichimura, M.; Gunasekaran, M.; Sueyoshi, T.

    2009-06-01

    The photochemical deposition (PCD) technique was applied for solar cells and gas sensors. CdS and Cd1-xZnxS were deposited by PCD. Thiosulfate ions S2O32- act as a reductant and a sulfur source. The SnS absorption layer was deposited by three-step pulse electrochemical deposition. For the CdS/SnS structure, the best cell showed an efficiency of about 0.2%, while for the Cd1-xZnxS/SnS structure, an efficiency of up to 0.7% was obtained. For the gas sensor application, SnO2 was deposited by PCD from a solution containing SnSO4 and HNO3. To enhance the sensitivity to hydrogen, Pd was doped by the photochemical doping method. The current increased by a factor of 104 upon exposure to 5000 ppm hydrogen within 1 min at room temperature. 103 times conductivity increase was observed even for 50 ppm hydrogen.

  6. Zinspy Sensors with Enhanced Dynamic Range for Imaging Neuronal Cell Zinc Uptake and Mobilization

    PubMed Central

    Nolan, Elizabeth M.; Ryu, Jubin W.; Jaworski, Jacek; Feazell, Rodney P.; Sheng, Morgan; Lippard, Stephen J.

    2006-01-01

    Thiophene moieties were incorporated into previously described Zinspy (ZS) fluorescent Zn(II) sensor motifs (Nolan, E. M.; Lippard, S. J. Inorg. Chem. 2004, 43, 8310–8317) to provide enhanced fluorescence properties, low-micromolar dissociation constants for Zn(II), and improved Zn(II) selectivity. Halogenation of the xanthenone and benzoate moieties of the fluorescein platform systematically modulates the excitation and emission profiles, pH-dependent fluorescence, Zn(II) affinity, and Zn(II) complexation rates, offering a general strategy for tuning multiple properties of xanthenone-based metal ion sensors. Extensive biological studies in cultured cells and primary neuronal cultures demonstrate 2-{6-hydroxy-3-oxo-4,5-bis[(pyridin-2-ylmethylthiophen-2-ylmethylamino)methyl]-3H-xanthen-9-yl}benzoic acid (ZS5) to be a versatile imaging tool for detecting Zn(II) in vivo. ZS5 localizes to the mitochondria of HeLa cells and allows visualization of glutamate-mediated Zn(II) uptake in dendrites and Zn(II) release resulting from nitrosative stress in neurons. PMID:17132019

  7. A cell phone based health monitoring system with self analysis processor using wireless sensor network technology.

    PubMed

    Chung, Wan-Young; Yau, Chiew-Lian; Shin, Kwang-Sig; Myllyla, Risto

    2007-01-01

    This paper describes the integrated wireless CDMA-based ubiquitous healthcare monitoring system for disease and chronic management and better patient care in the hospital, home or travel environments with extended standalone simple electrocardiogram (ECG) diagnosis algorithm at cell phone. This system utilizes a wireless dongles prototype as the intermediary devices to remotely monitor the physiological signs of patient's from a tiny wireless sensor to transmit directly to medical center monitoring/PDA wirelessly within 802.15.4 wireless LAN or using cell phone to relay the medical data through CDMA network when outside the coverage LAN. The external standalone ECG diagnosis was implemented to enable continuous monitoring and evaluation of the ECG signal locally before any medical data could be sent to the medical center.

  8. Fast and accurate detection of cancer cell using a versatile three-channel plasmonic sensor

    NASA Astrophysics Data System (ADS)

    Hoseinian, M.; Ahmadi, A. R.; Bolorizadeh, M. A.

    2016-09-01

    Surface Plasmon Resonance (SPR) optical fiber sensors can be used as cost-effective small sized biosensors that are relatively simple to operate. Additionally, these instruments are label-free, hence rendering them highly sensitive to biological measurements. In this study, a three-channel microstructure optical fiber plasmonic-based portable biosensor is designed and analyzed using Finite Element Method. The proposed system is capable of determining changes in sample's refractive index with precision of order one thousandth. The biosensor measures three absorption resonance wavelengths of the analytes simultaneously. This property is one of the main advantages of the proposed biosensor since it reduces the error in the measured wavelength and enhances the accuracy of the results up to 10-5 m/RIU by reducing noise. In this paper, Jurkat cell, an indicator cell for leukemia cancer, is considered as the analyte; and its absorption resonance wavelengths as well as sensitivity in each channel are determined.

  9. Mushroom body miscellanea: transgenic Drosophila strains expressing anatomical and physiological sensor proteins in Kenyon cells

    PubMed Central

    Pech, Ulrike; Dipt, Shubham; Barth, Jonas; Singh, Priyanka; Jauch, Mandy; Thum, Andreas S.; Fiala, André; Riemensperger, Thomas

    2013-01-01

    The fruit fly Drosophila melanogaster represents a key model organism for analyzing how neuronal circuits regulate behavior. The mushroom body in the central brain is a particularly prominent brain region that has been intensely studied in several insect species and been implicated in a variety of behaviors, e.g., associative learning, locomotor activity, and sleep. Drosophila melanogaster offers the advantage that transgenes can be easily expressed in neuronal subpopulations, e.g., in intrinsic mushroom body neurons (Kenyon cells). A number of transgenes has been described and engineered to visualize the anatomy of neurons, to monitor physiological parameters of neuronal activity, and to manipulate neuronal function artificially. To target the expression of these transgenes selectively to specific neurons several sophisticated bi- or even multipartite transcription systems have been invented. However, the number of transgenes that can be combined in the genome of an individual fly is limited in practice. To facilitate the analysis of the mushroom body we provide a compilation of transgenic fruit flies that express transgenes under direct control of the Kenyon-cell specific promoter, mb247. The transgenes expressed are fluorescence reporters to analyze neuroanatomical aspects of the mushroom body, proteins to restrict ectopic gene expression to mushroom bodies, or fluorescent sensors to monitor physiological parameters of neuronal activity of Kenyon cells. Some of the transgenic animals compiled here have been published already, whereas others are novel and characterized here for the first time. Overall, the collection of transgenic flies expressing sensor and reporter genes in Kenyon cells facilitates combinations with binary transcription systems and might, ultimately, advance the physiological analysis of mushroom body function. PMID:24065891

  10. Fiber-optic voltage sensor

    NASA Astrophysics Data System (ADS)

    Wood, C. B.

    1990-07-01

    A fiber-optic voltage sensor is described which includes a source of light, a reference fiber for receiving a known percentage of the light and an electrostrictive element having terminals across which is applied, and a voltage to be measured. The electrostrictive element is responsive to the applied voltage to assume an altered physical state. A measuring fiber also receives a known percentage of light from the light source and is secured about the electrostrictive element. The measuring fiber is provided with a cladding and exhibits an evanescent wave in the cladding. The measuring fiber has a known length which is altered when the electrostrictive element assumes its altered physical state. A differential sensor is provided which senses the intensity of light in both the reference fiber and the measuring fiber and provides an output indicative of the difference between the intensities.

  11. An Evanescent Microwave Probe for Super-Resolution Nondestructive Imaging of Metals, Semiconductors, Dielectrics, Composites and Biological Specimens

    NASA Technical Reports Server (NTRS)

    Pathak, P. S.; Tabib-Azar, M.; Ponchak, G.

    1998-01-01

    Using evanescent microwaves with decay lengths determined by a combination of microwave wavelength (lambda) and waveguide termination geometry, we have imaged and mapped material non-uniformities and defects with a resolving capability of lambda/3800=79 microns at 1 GHz. In our method a microstrip quarter wavelength resonator was used to generate evanescent microwaves. We imaged materials with a wide range of conductivities. Carbon composites, dielectrics (Duroid, polymers), semiconductors (3C-SiC, polysilicon, natural diamond), metals (tungsten alloys, copper, zinc, steel), high-temperature superconductors, and botanical samples were scanned for defects, residual stresses, integrity of brazed junctions, subsurface features, areas of different film thickness and moisture content. The evanescent microwave probe is a versatile tool and it can be used to perform very fast, large scale mapping of a wide range of materials. This method of characterization compares favorably with ultrasound testing, which has a resolution of about 0.1 mm and suffers from high absorption in composite materials and poor transmission across boundaries. Eddy current methods which can have a resolution on the order of 50 microns are restricted to evaluating conducting materials. Evanescent microwave imaging, with careful choice of operating frequency and probe geometry, can have a resolution of up to 1 micron. In this method we can scan hot and moving objects, sample preparation is not required, testing is non-destructive, non-invasive and non-contact, and can be done in air, in liquid or in vacuum.

  12. Mid-infrared fiber-optic evanescent field spectroscopy for in situ monitoring of tetrahydrofuran hydrate formation and dissociation.

    PubMed

    Schwenk, M; Katzir, A; Mizaikoff, B

    2017-02-27

    Tetrahydrofuran is a relevant auxiliary molecule when storing carbon dioxide or hydrocarbons as gas hydrates. The present study demonstrates the application of in situ mid-infrared fiber-optic evanescent field absorption spectroscopy for studying the formation and dissociation of THF hydrates. Thereby, the utility of this analytical technique for providing unique molecular-level insight even under harsh environmental conditions is evidenced.

  13. Highly Stretchable Fully-Printed CNT-Based Electrochemical Sensors and Biofuel Cells: Combining Intrinsic and Design-Induced Stretchability.

    PubMed

    Bandodkar, Amay J; Jeerapan, Itthipon; You, Jung-Min; Nuñez-Flores, Rogelio; Wang, Joseph

    2016-01-13

    We present the first example of an all-printed, inexpensive, highly stretchable CNT-based electrochemical sensor and biofuel cell array. The synergistic effect of utilizing specially tailored screen printable stretchable inks that combine the attractive electrical and mechanical properties of CNTs with the elastomeric properties of polyurethane as a binder along with a judiciously designed free-standing serpentine pattern enables the printed device to possess two degrees of stretchability. Owing to these synergistic design and nanomaterial-based ink effects, the device withstands extremely large levels of strains (up to 500% strain) with negligible effect on its structural integrity and performance. This represents the highest stretchability offered by a printed device reported to date. Extensive electrochemical characterization of the printed device reveal that repeated stretching, torsional twisting, and indenting stress has negligible impact on its electrochemical properties. The wide-range applicability of this platform to realize highly stretchable CNT-based electrochemical sensors and biofuel cells has been demonstrated by fabricating and characterizing potentiometric ammonium sensor, amperometric enzyme-based glucose sensor, enzymatic glucose biofuel cell, and self-powered biosensor. Highly stretchable printable multianalyte sensor, multifuel biofuel cell, or any combination thereof can thus be realized using the printed CNT array. Such combination of intrinsically stretchable printed nanomaterial-based electrodes and strain-enduring design patterns holds considerable promise for creating an attractive class of inexpensive multifunctional, highly stretchable printed devices that satisfy the requirements of diverse healthcare and energy fields wherein resilience toward extreme mechanical deformations is mandatory.

  14. A miniature porous aluminum oxide-based flow-cell for online water quality monitoring using bacterial sensor cells.

    PubMed

    Yagur-Kroll, Sharon; Schreuder, Erik; Ingham, Colin J; Heideman, René; Rosen, Rachel; Belkin, Shimshon

    2015-02-15

    The use of live bacterial reporters as sensing entities in whole-cell biosensors allows the investigation of the biological effects of a tested sample, as well as the bioavailability of its components. Here we present a proof of concept for a new design for online continuous water monitoring flow-cell biosensor, incorporating recombinant reporter bacteria, engineered to generate an optical signal (fluorescent or bioluminescent) in the presence of the target compound(s). At the heart of the flow-cell is a disposable chip made of porous aluminum oxide (PAO), which retains the sensor microorganisms on its rigid planar surface, while its high porosity allows an undisturbed access both to the sample and to essential nutrients. The ability of the bacterial reporters to detect model toxic chemicals was first demonstrated using a "naked" PAO chip placed on solid agar, and later in a chip encased in a specially designed flow-through configuration which enables continuous on-line monitoring. The applicability of the PAO chip to simultaneous online detection of diverse groups of chemicals was demonstrated by the incorporation of a 6-member sensor array into the flow-through chip. The selective response of the array was also confirmed in spiked municipal wastewater effluents. Sensing activity was retained by the bacteria after 12-weeks storage of freeze-dried biochips, demonstrating the biochip potential as a simple minimal maintenance "plug-in" cartridge. This low-cost and easy to handle PAO-based flow-cell biosensor may serve as a basis for a future platform for water quality monitoring.

  15. Dynamic Monitoring of Mechano-Sensing of Cells by Gold Nanoslit Surface Plasmon Resonance Sensor

    PubMed Central

    Wu, Shu-Han; Lee, Kuang-Li; Weng, Ruei-Hung; Zheng, Zhao-Xian; Chiou, Arthur; Wei, Pei-Kuen

    2014-01-01

    We demonstrated a real-time monitoring of live cells upon laminar shear stress stimulation via surface plasmon resonance (SPR) in gold nanoslit array. A large-area gold nanostructure consisted of 500-nm-period nanoslits was fabricated on a plastic film using the thermal-annealed template-stripping method. The SPR in the gold nanoslit array provides high surface sensitivity to monitor cell adhesion changes near the sensor surface. The human non-small cell lung cancer (CL1-0), human lung fibroblast (MRC-5), and human dermal fibroblast (Hs68) were cultured on the gold nanoslits and their dynamic responses to laminar shear stress were measured under different stress magnitudes from 0 to 30 dyne/cm2. Cell adhesion was increased in CL1-0 under shear flow stimulation. No adhesion recovery was observed after stopping the flow. On the other hand, MRC-5 and Hs68 decreased adhesion and recovered from the shear stress. The degree of recovery was around 70% for MRC-5. This device provides dynamic study and early detection of cell adhesion changes under shear flow conditions. PMID:24586846

  16. Part of evanescent modes in the normally incident gravity surface wave's energy layout around a submerged obstacle

    NASA Astrophysics Data System (ADS)

    Charland, J.; Rey, V.; Touboul, J.

    2012-04-01

    Part of evanescent modes in the normally incident gravity surface wave's energy layout around a submerged obstacle Jenna Charland *1, Vincent Rey *2, Julien Touboul *2 *1 Mediterraneen Institute of Oceanography. Institut des Sciences de l'Ingénieur Toulon-Var. Avenue Georges Pompidou, BP 56, 83162 La Valette du Var Cedex, France. Centre National de la Recherche Scientifique, Délégation Normandie. Projet soutenu financièrement par la Délégation Générale de l'Armement. *2 Mediterraneen Institute of Oceanography. Institut des Sciences de l'Ingénieur Toulon-Var. Avenue Georges Pompidou, BP 56, 83162 La Valette du Var Cedex, France. During the last decades various studies have been performed to understand the wave propagation over varying bathymetries. Few answers related to this non linear problem were given by the Patarapanich's studies which described the reflection coefficient of a submerged plate as a function of the wavelength. Later Le-Thi-Minh [2] demonstrated the necessity of taking into account the evanescent modes to better describe the propagation of waves over a varying bathymetry. However, all these studies stare at pseudo-stationary state that allows neither the comprehension of the transient behaviour of propagative modes nor the role of the evanescent modes in this unstationnary process. Our study deals with the wave establishment over a submerged plate or step and focuses on the evanescent modes establishment. Rey [3] described the propagation of a normally incident surface gravity wave over a varying topography on the behaviour of the fluid using a linearized potential theory solved by a numerical model using an integral method. This model has a large field of application and has been adapted to our case. This code still solves a stationary problem but allows us to calculate the contribution of the evanescent modes in the energy layout around a submerged plate or a submerged step. The results will show the importance of the trapped energy

  17. Dual functions for the endoplasmic reticulum calcium sensors STIM1 and STIM2 in T cell activation and tolerance

    PubMed Central

    Oh-hora, Masatsugu; Yamashita, Megumi; Hogan, Patrick G; Sharma, Sonia; Lamperti, Ed; Chung, Woo; Prakriya, Murali; Feske, Stefan; Rao, Anjana

    2009-01-01

    Store-operated Ca2+ entry through calcium release–activated calcium channels is the chief mechanism for increasing intracellular Ca2+ in immune cells. Here we show that mouse T cells and fibroblasts lacking the calcium sensor STIM1 had severely impaired store-operated Ca2+ influx, whereas deficiency in the calcium sensor STIM2 had a smaller effect. However, T cells lacking either STIM1 or STIM2 had much less cytokine production and nuclear translocation of the transcription factor NFAT. T cell–specific ablation of both STIM1 and STIM2 resulted in a notable lymphoproliferative phenotype and a selective decrease in regulatory T cell numbers. We conclude that both STIM1 and STIM2 promote store-operated Ca2+ entry into T cells and fibroblasts and that STIM proteins are required for the development and function of regulatory T cells. PMID:18327260

  18. Cell-based sensor system using L6 cells for broad band continuous pollutant monitoring in aquatic environments.

    PubMed

    Kubisch, Rebekka; Bohrn, Ulrich; Fleischer, Maximilian; Stütz, Evamaria

    2012-01-01

    Pollution of drinking water sources represents a continuously emerging problem in global environmental protection. Novel techniques for real-time monitoring of water quality, capable of the detection of unanticipated toxic and bioactive substances, are urgently needed. In this study, the applicability of a cell-based sensor system using selected eukaryotic cell lines for the detection of aquatic pollutants is shown. Readout parameters of the cells were the acidification (metabolism), oxygen consumption (respiration) and impedance (morphology) of the cells. A variety of potential cytotoxic classes of substances (heavy metals, pharmaceuticals, neurotoxins, waste water) was tested with monolayers of L6 cells (rat myoblasts). The cytotoxicity or cellular effects induced by inorganic ions (Ni(2+) and Cu(2+)) can be detected with the metabolic parameters acidification and respiration down to 0.5 mg/L, whereas the detection limit for other substances like nicotine and acetaminophen are rather high, in the range of 0.1 mg/L and 100 mg/L. In a close to application model a real waste water sample shows detectable signals, indicating the existence of cytotoxic substances. The results support the paradigm change from single substance detection to the monitoring of overall toxicity.

  19. Imaging of Dynamic Secretory Vesicles in Living Pollen Tubes of Picea meyeri Using Evanescent Wave Microscopy1[W

    PubMed Central

    Wang, Xiaohua; Teng, Yan; Wang, Qinli; Li, Xiaojuan; Sheng, Xianyong; Zheng, Maozhong; Šamaj, Jozef; Baluška, František; Lin, Jinxing

    2006-01-01

    Evanescent wave excitation was used to visualize individual, FM4-64-labeled secretory vesicles in an optical slice proximal to the plasma membrane of Picea meyeri pollen tubes. A standard upright microscope was modified to accommodate the optics used to direct a laser beam at a variable angle. Under evanescent wave microscopy or total internal reflection fluorescence microscopy, fluorophores localized near the surface were excited with evanescent waves, which decay exponentially with distance from the interface. Evanescent waves with penetration depths of 60 to 400 nm were generated by varying the angle of incidence of the laser beam. Kinetic analysis of vesicle trafficking was made through an approximately 300-nm optical section beneath the plasma membrane using time-lapse evanescent wave imaging of individual fluorescently labeled vesicles. Two-dimensional trajectories of individual vesicles were obtained from the resulting time-resolved image stacks and were used to characterize the vesicles in terms of their average fluorescence and mobility, expressed here as the two-dimensional diffusion coefficient D2. The velocity and direction of vesicle motions, frame-to-frame displacement, and vesicle trajectories were also calculated. Analysis of individual vesicles revealed for the first time, to our knowledge, that two types of motion are present, and that vesicles in living pollen tubes exhibit complicated behaviors and oscillations that differ from the simple Brownian motion reported in previous investigations. Furthermore, disruption of the actin cytoskeleton had a much more pronounced effect on vesicle mobility than did disruption of the microtubules, suggesting that actin cytoskeleton plays a primary role in vesicle mobility. PMID:16798949

  20. Transmission of evanescent wave modes through a slab of negative-refractive-index material.

    PubMed

    de Wolf, David A

    2011-02-01

    There has been a long-standing argument about Pendry's suggestion that a plane harmonic evanescent (surface) wave along the interface between free space and a slab of ɛ=-1, μ=-1 double-negative (DNG) medium will emerge on the far side with recovery of phase and amplitude. While this is possible, it is subject to parameter restrictions. This work generalizes previous work and now gives analytical criteria for when to expect such a recovery in a Smith-Kroll DNG medium. Basically this requires, among other things, a relatively narrow bandwidth and relatively small transverse-mode component. There also is a very strong dependence on the ratio of slabwidth to plasma wavelength.

  1. Carbon nanotube mode lockers with enhanced nonlinearity via evanescent field interaction in D-shaped fibers.

    PubMed

    Song, Yong-Won; Yamashita, Shinji; Goh, Chee S; Set, Sze Y

    2007-01-15

    We demonstrate a novel passive mode-locking scheme for pulsed lasers enhanced by the interaction of carbon nanotubes (CNTs) with the evanescent field of propagating light in a D-shaped optical fiber. The scheme features all-fiber operation as well as a long lateral interaction length, which guarantees a strong nonlinear effect from the nanotubes. Mode locking is achieved with less than 30% of the CNTs compared with the amount of nanotubes used for conventional schemes. Our method also ensures the preservation of the original morphology of the individual CNTs. The demonstrated pulsed laser with our CNT mode locker has a repetition rate of 5.88 MHz and a temporal pulse width of 470 fs.

  2. Carbon nanotube mode lockers with enhanced nonlinearity via evanescent field interaction in D-shaped fibers

    NASA Astrophysics Data System (ADS)

    Song, Yong-Won; Yamashita, Shinji; Goh, Chee S.; Set, Sze Y.

    2007-01-01

    We demonstrate a novel passive mode-locking scheme for pulsed lasers enhanced by the interaction of carbon nanotubes (CNTs) with the evanescent field of propagating light in a D-shaped optical fiber. The scheme features all-fiber operation as well as a long lateral interaction length, which guarantees a strong nonlinear effect from the nanotubes. Mode locking is achieved with less than 30% of the CNTs compared with the amount of nanotubes used for conventional schemes. Our method also ensures the preservation of the original morphology of the individual CNTs. The demonstrated pulsed laser with our CNT mode locker has a repetition rate of 5.88 MHz and a temporal pulse width of 470 fs.

  3. Optical refractive index biosensor using evanescently coupled lateral Bragg gratings on silicon-on-insulator

    NASA Astrophysics Data System (ADS)

    Mendez-Astudillo, Manuel; Takahisa, Hiroki; Okayama, Hideaki; Nakajima, Hirochika

    2016-08-01

    In this paper, we present a compact silicon-on-insulator optical biosensor based on lateral Bragg gratings evanescently coupled to a waveguide. The device is fabricated by electron-beam lithography and dry-etched in a single step with inductive coupled plasma reactive ion etching (ICP-RIE). Fully etched grating couplers are used to couple the light in and out of the chip, while lateral Bragg gratings are used as the sensing element of the device. A sensitivity of 22 nm/RIU is obtained by exposing the device to deionized water with different NaCl concentrations with a footprint area of 15 × 4 µm2 that allows for densely multiplexed solutions.

  4. Evanescent excitation and collection of spontaneous Raman spectra using silicon nitride nanophotonic waveguides.

    PubMed

    Dhakal, Ashim; Subramanian, Ananth Z; Wuytens, Pieter; Peyskens, Frédéric; Le Thomas, Nicolas; Baets, Roel

    2014-07-01

    We experimentally demonstrate the use of high contrast, CMOS-compatible integrated photonic waveguides for Raman spectroscopy. We also derive the dependence of collected Raman power with the waveguide parameters and experimentally verify the derived relations. Isopropyl alcohol (IPA) is evanescently excited and detected using single-mode silicon-nitride strip waveguides. We analyze the measured signal strength of pure IPA corresponding to an 819  cm⁻¹ Raman peak due to in-phase C-C-O stretch vibration for several waveguide lengths and deduce a pump power to Raman signal conversion efficiency on the waveguide to be at least 10⁻¹¹  per cm.

  5. Detection of C-reactive protein in evanescent wave field using microparticle-tracking velocimetry.

    PubMed

    Fan, Yu-Jui; Sheen, Horn-Jiunn; Liu, Yi-Hsing; Tsai, Jing-Fa; Wu, Tzu-Heng; Wu, Kuang-Chong; Lin, Shiming

    2010-09-07

    A new technique is developed to measure the nanoparticles' brownian motions by employing microparticle-tracking velocimetry (micro-PTV) in evanescent wave field, which can provide high signal-to-noise ratio images for analyzing nanoparticles' movements. This method enables real-time detection of C-reactive proteins (CRPs) during the rapid interaction between CRPs and anti-CRP-coated nanobeads as CRP concentrations are related to the nanobeads' brownian velocity in the equilibrium state. The smallest observable nanobeads with 185 nm were utilized in this experiment to detect CRP concentrations as low as 0.1 microg/mL even in a high-viscosity solution. Further, the dissociation constant, K(D), can be evaluated based on the experimental results.

  6. Evanescent Microwave Probes on High-Resistivity Silicon and its Application in Characterization of Semiconductors

    NASA Technical Reports Server (NTRS)

    Tabib-Azar, M.; Akinwande, D.; Ponchak, George E.; LeClair, S. R.

    1999-01-01

    In this article we report the design, fabrication, and characterization of very high quality factor 10 GHz microstrip resonators on high-resistivity (high-rho) silicon substrates. Our experiments show that an external quality factor of over 13 000 can be achieved on microstripline resonators on high-rho silicon substrates. Such a high Q factor enables integration of arrays of previously reported evanescent microwave probe (EMP) on silicon cantilever beams. We also demonstrate that electron-hole pair recombination and generation lifetimes of silicon can be conveniently measured by illuminating the resonator using a pulsed light. Alternatively, the EMP was also used to nondestructively monitor excess carrier generation and recombination process in a semiconductor placed near the two-dimensional resonator.

  7. Hollow-fiber evanescent light-wave atom-bottle trap

    NASA Astrophysics Data System (ADS)

    Dowling, Jonathan P.

    1997-05-01

    Recent theoretical and experimental demonstrations have shown that blue-detuned laser light, propagating in the annular core-cladding region of a hollow-glass fiber, produces a repulsive, evanescent light-wave potential in the hollow, that can be used to guide near-resonant atoms down the fiber. In this work, I show that slight modifications to the hollow-fiber geometry can be used to turn this atom guide into an atom-bottle trap. The trap can be open and shut by varying the aperture angle at which light couples into the fiber, allowing the atoms to be easily loaded. This trap has an advantage over other optical atom traps in that the atoms move coherently in a field-free region with only brief specular reflections at the step-like potential walls.

  8. Evanescent pressure gradient response in the upper ocean to subinertial wind stress forcing of finite wavelength

    NASA Technical Reports Server (NTRS)

    White, Warren B.; Mcnally, Gerard

    1987-01-01

    A schematic model is used to interpret field observations related to the mixed layer response to wind stress at subinertial frequencies. It is shown that subinertial density and pressure fluctuations can arise locally from the finite wavelength character of the wind stress forcing as a fundamental part of the upper ocean transient, wind-driven response on time scales of 2-10 pendulum days. Evanescent vertical motions arise which alter the density field of the pycnocline, and hence the pressure field over the entire upper ocean. It is thus found that in the real ocean driven by wind stress, a transient geostrophic response exists which can be as large or larger than the transient Eckman response.

  9. Observation of the formation of anisotropic silver microstructures by evanescent wave and electron microscopy

    NASA Astrophysics Data System (ADS)

    Pal, Angshuman; Khajornrungruang, Panart; Netzband, Christopher; Alety, Sriveda; Babu, S. V.

    2016-02-01

    Using a well-known galvanic displacement reaction, ˜25-40 μm long silver ribbons grown after mixing ˜50 nm copper particles with AgNO3 solution were observed as a function of Ag+ concentration and their growth was characterized in real-time and in situ by evanescent wave (EW) microscopy. At low Ag+ concentration, chain-like structures consisting of both Ag and Cu were observed. When the sequence of mixing these two reactants was reversed, different Ag microstructures (platelets and dendrites) were formed and were also characterized by EW microscopy. Dependence of the morphology of all these microstructures on silver ion concentration was determined by EW microscopy in conjunction with scanning and transmission electron microscopy.

  10. Ultrasensitive evanescent wave fluoro-immunosensors using polystyrene integrated lens optical fiber

    NASA Astrophysics Data System (ADS)

    Lin, Jinn-Nan; Mahoney, Walter C.; Luderer, Albert A.; Brier, Rick A.; Sharp, Tom W.; McGuire, Verna A.

    1994-07-01

    A sensitive evanescent wave immunoassay is described for assay of human chorionic gonadotropin (hCG) in plasma using molded polystyrene optical fibers. Data was processed using kinetic parameters which allowed a total assay time of two minutes. The characterization of two longer wavelength dyes (allophycocyanin and Cy5) in relation to FITC is described and their effect on assay signal was studied. APC had six times the fluorescence intensity of FITC and generated forty times the signal in the hCG assay format. Native, acid-treated and biotinylated antibody immobilization chemistries and their surface density effects were investigated to determine the effect on assay signal. Native antibody generated approximately 50% of the signal versus acid-treated or biotinylated and a 50% reduction in the surface antibody concentration showed little effect on assay signal. The assay agreed well with a commercially available assay (ES-300) and has a sensitivity of 0.8 mIU/ml.

  11. Nanolithography in evanescent near field by using nano-filmed noble metal layers

    NASA Astrophysics Data System (ADS)

    Yang, Yong; Hu, Song; Yao, Hanmin; Cheng, Guanxiao; Yan, Wei

    2007-12-01

    Nanolithography has been investigated by using optical proximity exposure in the evanescent near field in nano-filmed noble metals. Sub-diffraction-limited feature size can be resolved by using i-line illumination exposure. Compared with the model of original superlens, we separated the superlens 100nm away from the mask, under the illumination of i-line light, the initial simulation shows that the sub-diffraction-limited feature as small as 60nm linewidth with 120nm pitch can be clearly resolved without hard contact between mask and nano-filmed noble metal. By proper design of the materials and the parameters of nano-filmed layers, better resolution can be realized.

  12. Near-Field Nanofluid Concentration Measurement by Rayleigh Particle Scattering Bragg Grating Evanescent Wave

    NASA Astrophysics Data System (ADS)

    Huang, Xue-Feng; Li, Sheng-Ji

    2014-04-01

    We report an approach to detect near-field nanofluid concentration by scattering Bragg grating evanescent wave (EW). Since the suspended nanoparticles can enhance the scattering intensity of the EW from the thinned and tapered fiber with Bragg grating, the reflectance ratio of Bragg grating is dependent on the corresponding refractive index (RI) of the nanofluid at different nanoparticle volume fraction. A critical reflectance ratio measurement identifies the nanofluid concentration. Theory and simulation of scattering Bragg grating EW was analyzed. The scattering Bragg grating EW fiber sensing probe was designed and fabricated by the wet chemical etching method, and calibration was made by several chemical solutions without suspended nanoparticles. The example application of the nanofluid containing dispersed 40 nm SiO2 nanoparticles demonstrates the feasibility. The reflectance ratio decreases by over 3.2% with the nanofluid concentration increasing from 0.25 wt.% to 4 wt.%, while the temperature disturbance can be negligible.

  13. Structure fits the purpose: photonic crystal fibers for evanescent-field surface-enhanced Raman spectroscopy.

    PubMed

    Khaing Oo, Maung Kyaw; Han, Yun; Kanka, Jiri; Sukhishvili, Svetlana; Du, Henry

    2010-02-15

    We report numerical simulation and hyperspectral Raman imaging of three index-guiding solid-core photonic crystal fibers (PCFs) of different air-cladding microstructures to assess their respective potential for evanescent-field Raman spectroscopy, with an emphasis on achieving surface-enhanced Raman scattering (SERS) over the entire fiber length. Suspended-core PCF consisting of a silica core surrounded by three large air channels conjoined by a thin silica web is the most robust of the three SERS-active PCFs, with a demonstrated detection sensitivity of 1x10(-10) M R6G in an aqueous solution of only approximately 7.3 microL sampling volume.

  14. Large photon drag effect of intrinsic graphene induced by plasmonic evanescent field

    NASA Astrophysics Data System (ADS)

    Luo, Ma; Li, Zhibing

    2016-12-01

    A large photon drag effect of the massless Dirac fermions in intrinsic graphene is predicted for a graphene-on-plasmonic-layer system. The surface plasmons in the plasmonic layer enlarge the wave number of the photon hundreds times more than in vacuum. The evanescent field of the surface plasmons generates a directional motion of carriers in the intrinsic graphene because of the large momentum transfer from the surface plasmon to the excited carriers. A model Hamiltonian is developed on the assumption that the in-plane wavelength of the surface plasmons is much smaller than the mean free path of the carriers. The time evolution of the density matrix is solved by perturbation method as well as numerical integration. The nondiagonal density matrix elements with momentum transfer lead to a gauge current, which is an optically driven macroscopic direct current. The dependence of the macroscopic direct current on the incident direction and intensity of the laser field is studied.

  15. Development of a diagnostic sensor for measuring blood cell concentrations during haemoconcentration

    PubMed Central

    Robertson, Craig A.; Gourlay, Terence

    2016-01-01

    Background: HemoSep® is a commercial ultrafiltration and haemoconcentration device for the concentration of residual bypass blood following surgery. This technology is capable of reducing blood loss in cardiac and other types of “clean site” procedures, including paediatric surgery. Clinical feedback suggested that the device would be enhanced by including a sensor technology capable of discerning the concentration level of the processed blood product. We sought to develop a novel sensor that can, using light absorption, give an accurate estimate of packed cell volume (PCV). Materials and methods: A sensor-housing unit was 3D printed and the factors influencing the sensor’s effectiveness – supply voltage, sensitivity and emitter intensity - were optimised. We developed a smart system, using comparator circuitry capable of visually informing the user when adequate PCV levels (⩾35%) are attained by HemoSep® blood processing, which ultimately indicates that the blood is ready for autotransfusion. Results: Our data demonstrated that the device was capable of identifying blood concentration at and beyond the 35% PCV level. The device was found to be 100% accurate at identifying concentration levels of 35% from a starting level of 20%. Discussion: The sensory capability was integrated into HemoSep’s® current device and is designed to enhance the user’s clinical experience and to optimise the benefits of HemoSep® therapy. The present study focused on laboratory studies using bovine blood. Further studies are now planned in the clinical setting to confirm the efficacy of the device. PMID:27591743

  16. A nano-microstructured artificial-hair-cell-type sensor based on topologically graded 3D carbon nanotube bundles

    NASA Astrophysics Data System (ADS)

    Yilmazoglu, O.; Yadav, S.; Cicek, D.; Schneider, J. J.

    2016-09-01

    A design for a unique artificial-hair-cell-type sensor (AHCTS) based entirely on 3D-structured, vertically aligned carbon nanotube (CNT) bundles is introduced. Standard microfabrication techniques were used for the straightforward micro-nano integration of vertically aligned carbon nanotube arrays composed of low-layer multi-walled CNTs (two to six layers). The mechanical properties of the carbon nanotube bundles were intensively characterized with regard to various substrates and CNT morphology, e.g. bundle height. The CNT bundles display excellent flexibility and mechanical stability for lateral bending, showing high tear resistance. The integrated 3D CNT sensor can detect three-dimensional forces using the deflection or compression of a central CNT bundle which changes the contact resistance to the shorter neighboring bundles. The complete sensor system can be fabricated using a single chemical vapor deposition (CVD) process step. Moreover, sophisticated external contacts to the surroundings are not necessary for signal detection. No additional sensors or external bias for signal detection are required. This simplifies the miniaturization and the integration of these nanostructures for future microsystem set-ups. The new nanostructured sensor system exhibits an average sensitivity of 2100 ppm in the linear regime with the relative resistance change per micron (ppm μm-1) of the individual CNT bundle tip deflection. Furthermore, experiments have shown highly sensitive piezoresistive behavior with an electrical resistance decrease of up to ˜11% at 50 μm mechanical deflection. The detection sensitivity is as low as 1 μm of deflection, and thus highly comparable with the tactile hair sensors of insects, having typical thresholds on the order of 30-50 μm. The AHCTS can easily be adapted and applied as a flow, tactile or acceleration sensor as well as a vibration sensor. Potential applications of the latter might come up in artificial cochlear systems. In

  17. Quantitative high-resolution sensing of DNA hybridization using magnetic tweezers with evanescent illumination.

    PubMed

    Oliver, Piercen M; Park, Jin Seon; Vezenov, Dmitri

    2011-02-01

    We applied the combined approach of evanescent nanometry and force spectroscopy using magnetic tweezers to quantify the degree of hybridization of a single synthetic single-stranded DNA oligomer to a resolution approaching a single-base. In this setup, the 200 nucleotide long DNA was covalently attached to the surface of an optically transparent solid support at one end and to the surface of a superparamagnetic fluorescent microsphere (force probe) at the other end. The force was applied to the probes using an electromagnet. The end-to-end molecular distance (i.e. out-of-image-plane position of the force probe) was determined from the intensity of the probe fluorescence image observed with total-internal reflectance microscopy. An equation of state for single stranded DNA molecules under tension (extensible freely jointed chain) was used to derive the penetration depth of the evanescent field and to calibrate the magnetic properties of the force probes. The parameters of the magnetic response of the force probes obtained from the equation of state remained constant when changing the penetration depth, indicating a robust calibration procedure. The results of such a calibration were also confirmed using independently measured probe-surface distances for probes mounted onto cantilevers of an atomic force microscope. Upon hybridization of the complementary 50 nucleotide-long oligomer to the surface-bound 200-mer, the changes in the force-distance curves were consistent with the quantitative conversion of 25% of the original single-stranded DNA to its double-stranded form, which was modeled as an elastic rod. The method presented here for quantifying the hybridization state of the single DNA molecules has potential for determining the degree of hybridization of individual molecules in a single molecule array with high accuracy.

  18. Thin-film dielectric elastomer sensors to measure the contraction force of smooth muscle cells

    NASA Astrophysics Data System (ADS)

    Araromi, O.; Poulin, A.; Rosset, S.; Favre, M.; Giazzon, M.; Martin-Olmos, C.; Liley, M.; Shea, H.

    2015-04-01

    The development of thin-film dielectric elastomer strain sensors for the characterization of smooth muscle cell (SMC) contraction is presented here. Smooth muscle disorders are an integral part of diseases such as asthma and emphysema. Analytical tools enabling the characterization of SMC function i.e. contractile force and strain, in a low-cost and highly parallelized manner are necessary for toxicology screening and for the development of new and more effective drugs. The main challenge with the design of such tools is the accurate measurement of the extremely low contractile cell forces expected as a result of SMC monolayer contraction (as low as ~ 100 μN). Our approach utilizes ultrathin (~5 μm) and soft elastomer membranes patterned with elastomer-carbon composite electrodes, onto which the SMCs are cultured. The cell contraction induces an in-plane strain in the elastomer membrane, predicted to be in the order 1 %, which can be measured via the change in the membrane capacitance. The cell force can subsequently be deduced knowing the mechanical properties of the elastomer membrane. We discuss the materials and fabrication methods selected for our system and present preliminary results indicating their biocompatibility. We fabricate functional capacitive senor prototypes with good signal stability over the several hours (~ 0.5% variation). We succeed in measuring in-plane strains of 1 % with our fabricated devices with good repeatability and signal to noise ratio.

  19. Degron protease blockade sensor to image epigenetic histone protein methylation in cells and living animals.

    PubMed

    Sekar, Thillai V; Foygel, Kira; Devulapally, Rammohan; Paulmurugan, Ramasamy

    2015-01-16

    Lysine methylation of histone H3 and H4 has been identified as a promising therapeutic target in treating various cellular diseases. The availability of an in vivo assay that enables rapid screening and preclinical evaluation of drugs that potentially target this cellular process will significantly expedite the pace of drug development. This study is the first to report the development of a real-time molecular imaging biosensor (a fusion protein, [FLuc2]-[Suv39h1]-[(G4S)3]-[H3-K9]-[cODC]) that can detect and monitor the methylation status of a specific histone lysine methylation mark (H3-K9) in live animals. The sensitivity of this sensor was assessed in various cell lines, in response to down-regulation of methyltransferase EHMT2 by specific siRNA, and in nude mice with lysine replacement mutants. In vivo imaging in response to a combination of methyltransferase inhibitors BIX01294 and Chaetocin in mice reveals the potential of this sensor for preclinical drug evaluation. This biosensor thus has demonstrated its utility in the detection of H3-K9 methylations in vivo and potential value in preclinical drug development.

  20. 2D ratiometric fluorescent pH sensor for tracking of cells proliferation and metabolism.

    PubMed

    Ma, Jun; Ding, Changqin; Zhou, Jie; Tian, Yang

    2015-08-15

    Extracellular pH plays a vital role no matter in physiological or pathological studies. In this work, a hydrogel, CD@Nile-FITC@Gel (Gel sensor), entrapping the ratiometric fluorescent probe CD@Nile-FITC was developed. The Gel sensor was successfully used for real-time extracellular pH monitoring. In the case of CD@Nile-FITC, pH-sensitive fluorescent dye fluorescein isothiocyanate (FITC) was chosen as the response signal for H(+) and Nile blue chloride (Nile) as the reference signal. The developed fluorescent probe exhibited high selectivity for pH over other metal ions and amino acids. Meanwhile, the carbon-dots-based inorganic-organic probe demonstrated excellent photostability against long-term light illumination. In order to study the extracellular pH change in processes of cell proliferation and metabolism, CD@Nile-FITC probe was entrapped in sodium alginate gel and consequently formed CD@Nile-FITC@Gel. The MTT assay showed low cytotoxicity of the Gel and the pH titration indicated that it could monitor the pH fluctuations linearly and rapidly within the pH range of 6.0-9.0, which is valuable for physiological pH determination. As expected, the real-time bioimaging of the probe was successfully achieved.

  1. A dual transcriptional reporter and CDK-activity sensor marks cell cycle entry and progression in C. elegans

    PubMed Central

    van Rijnberk, Lotte M.; van der Horst, Suzanne E. M.; van den Heuvel, Sander; Ruijtenberg, Suzan

    2017-01-01

    Development, tissue homeostasis and tumor suppression depend critically on the correct regulation of cell division. Central in the cell division process is the decision whether to enter the next cell cycle and commit to going through the S and M phases, or to remain temporarily or permanently arrested. Cell cycle studies in genetic model systems could greatly benefit from visualizing cell cycle commitment in individual cells without the need of fixation. Here, we report the development and characterization of a reporter to monitor cell cycle entry in the nematode C. elegans. This reporter combines the mcm-4 promoter, to reveal Rb/E2F-mediated transcriptional control, and a live-cell sensor for CDK-activity. The CDK sensor was recently developed for use in human cells and consists of a DNA Helicase fragment fused to eGFP. Upon phosphorylation by CDKs, this fusion protein changes in localization from the nucleus to the cytoplasm. The combined regulation of transcription and subcellular localization enabled us to visualize the moment of cell cycle entry in dividing seam cells during C. elegans larval development. This reporter is the first to reflect cell cycle commitment in C. elegans and will help further genetic studies of the mechanisms that underlie cell cycle entry and exit. PMID:28158315

  2. Design and Characterization of a Sensorized Microfluidic Cell-Culture System with Electro-Thermal Micro-Pumps and Sensors for Cell Adhesion, Oxygen, and pH on a Glass Chip

    PubMed Central

    Bonk, Sebastian M.; Stubbe, Marco; Buehler, Sebastian M.; Tautorat, Carsten; Baumann, Werner; Klinkenberg, Ernst-Dieter; Gimsa, Jan

    2015-01-01

    We combined a multi-sensor glass-chip with a microfluidic channel grid for the characterization of cellular behavior. The grid was imprinted in poly-dimethyl-siloxane. Mouse-embryonal/fetal calvaria fibroblasts (MC3T3-E1) were used as a model system. Thin-film platinum (Pt) sensors for respiration (amperometric oxygen electrode), acidification (potentiometric pH electrodes) and cell adhesion (interdigitated-electrodes structures, IDES) allowed us to monitor cell-physiological parameters as well as the cell-spreading behavior. Two on-chip electro-thermal micro-pumps (ETμPs) permitted the induction of medium flow in the system, e.g., for medium mixing and drug delivery. The glass-wafer technology ensured the microscopic observability of the on-chip cell culture. Connecting Pt structures were passivated by a 1.2 μm layer of silicon nitride (Si3N4). Thin Si3N4 layers (20 nm or 60 nm) were used as the sensitive material of the pH electrodes. These electrodes showed a linear behavior in the pH range from 4 to 9, with a sensitivity of up to 39 mV per pH step. The oxygen sensors were circular Pt electrodes with a sensor area of 78.5 μm2. Their sensitivity was 100 pA per 1% oxygen increase in the range from 0% to 21% oxygen (air saturated). Two different IDES geometries with 30- and 50-μm finger spacings showed comparable sensitivities in detecting the proliferation rate of MC3T3 cells. These cells were cultured for 11 days in vitro to test the biocompatibility, microfluidics and electric sensors of our system under standard laboratory conditions. PMID:26263849

  3. Bioimpedance microelectronics in a 24-microwell plate with metabolic-sensors for testing chemosensitivity of tumor cells and tissues

    NASA Astrophysics Data System (ADS)

    Schwarzenberger, T.; Demmel, F.; Becker, B.; Zottmann, M.; Wolf, P.; Kleinhans, R.; Brischwein, M.; Otto, A.; Wolf, B.

    2010-04-01

    Living cells react to external influences such as pharmacological agents in an intricate manner due to their complex internal signal processing. Cell reactions are an impact on vitality, cell-cell or cell-matrix interaction and morphological changes. A number of published techniques on impedance spectroscopy (IS) of adherent cells with planar electrodes address these changes. However, IS can merely serve as an indicator of cellular events rather than provide detailed information on a specific cell process. Thus our approach is a 24-microwell sensor-plate with impedance-electrodes in parallel to pH- and O2-sensors, capable of being integrated into a fully automated screening system. For the purpose of IS, high precision impedance-electronics have been developed based on integrated circuits and validated against a Solartron 1260 impedance analyzer. IS data is correlated to the metabolic-sensors and additionally compared with cell images shot by an inverse optical microscope which is also part of the screening system. Proof of principle is demonstrated by experimental growth monitoring of a MCF-7 culture and cellular response to chemotherapeutics. Furthermore, the potential to monitor living tissue probes is presented for the first time.

  4. A genetically encoded FRET lactate sensor and its use to detect the Warburg effect in single cancer cells.

    PubMed

    San Martín, Alejandro; Ceballo, Sebastián; Ruminot, Iván; Lerchundi, Rodrigo; Frommer, Wolf B; Barros, Luis Felipe

    2013-01-01

    Lactate is shuttled between and inside cells, playing metabolic and signaling roles in healthy tissues. Lactate is also a harbinger of altered metabolism and participates in the pathogenesis of inflammation, hypoxia/ischemia, neurodegeneration and cancer. Many tumor cells show high rates of lactate production in the presence of oxygen, a phenomenon known as the Warburg effect, which has diagnostic and possibly therapeutic implications. In this article we introduce Laconic, a genetically-encoded Forster Resonance Energy Transfer (FRET)-based lactate sensor designed on the bacterial transcription factor LldR. Laconic quantified lactate from 1 µM to 10 mM and was not affected by glucose, pyruvate, acetate, betahydroxybutyrate, glutamate, citrate, α-ketoglutarate, succinate, malate or oxalacetate at concentrations found in mammalian cytosol. Expressed in astrocytes, HEK cells and T98G glioma cells, the sensor allowed dynamic estimation of lactate levels in single cells. Used in combination with a blocker of the monocarboxylate transporter MCT, the sensor was capable of discriminating whether a cell is a net lactate producer or a net lactate consumer. Application of the MCT-block protocol showed that the basal rate of lactate production is 3-5 fold higher in T98G glioma cells than in normal astrocytes. In contrast, the rate of lactate accumulation in response to mitochondrial inhibition with sodium azide was 10 times lower in glioma than in astrocytes, consistent with defective tumor metabolism. A ratio between the rate of lactate production and the rate of azide-induced lactate accumulation, which can be estimated reversibly and in single cells, was identified as a highly sensitive parameter of the Warburg effect, with values of 4.1 ± 0.5 for T98G glioma cells and 0.07 ± 0.007 for astrocytes. In summary, this article describes a genetically-encoded sensor for lactate and its use to measure lactate concentration, lactate flux, and the Warburg effect in single

  5. A thermo-stabilized flow cell for surface plasmon resonance sensors in D-shaped plastic optical fibers

    NASA Astrophysics Data System (ADS)

    Cennamo, N.; Chiavaioli, F.; Trono, C.; Tombelli, S.; Giannetti, A.; Baldini, F.; Zeni, L.

    2016-05-01

    The first example of an optical sensor platform based on surface plasmon resonance (SPR) in a plastic optical fiber (POF) integrated into a thermo-stabilized flow cell for biochemical sensing applications is proposed. In this work, an IgG/anti-IgG assay was implemented as model bioassay, with the IgG biolayer deposited on the sensor gold surface and the biological target, anti-IgG, transported through a new thermo-stabilized flow cell. The experimental results show that the proposed device can be successfully used for label-free biochemical sensing. This complete optical sensor system can be used for the future reduction of the device cost and dimension, with the possibility of integrating the POF-SPR sensing platform with microfluidic and optoelectronic devices.

  6. The Modification of Fuel Cell-Based Breath Alcohol Sensor Materials to Improve Water Retention of Sensing Performance

    NASA Astrophysics Data System (ADS)

    Allan, Jesse

    Fuel cell based breath alcohol sensors (BrASs) are one of the most important tools used by law enforcement today. The ability to screen potentially intoxicated subjects with the ease, speed, and flexibility the BrAS can provide is unmatched by any other device of its kind. While these devices are used globally, they all suffer from a common deficiency: reliance on water. The ability of the fuel cell sensor to manage water content is one of the greatest fundamental challenges facing this technology today. In order to evaluate the fuel cell sensor device, a methodology was required that would allow in-house sensor testing to be coupled with a diagnostic testing method to not only test materials sensing performance, but also determine why a sensor behaved how it did. To do this, a next-generation fuel cell was designed specifically for sensor testing along with a test station that allowed for rapid response and sensor characteristics of a given material. The fuel cell was designed to allow in-situ testing of a membrane electrode assembly (MEA) of interest using cyclic voltammetry and electrochemical impedance spectroscopy. The in-house design was validated against a commercial cell to provide feedback on how materials in the in-house cell would behave in a commercial designed unit. The results showed that our cell with a commercial MEA behaved identically to a commercial cell with the same MEA. Following validation of our cell, common membrane materials were investigated to identify their suitability in a senor role. The materials chosen were designed for power generating devices, so they provided a benchmark to identify which properties would be important for sensor operation. It was found that while the Nafion membrane and sulfonated poly (ether ether ketone) did show performance increases over the commercial MEA, the thin characteristics of these membranes limited performance in drier conditions. From these results, it was determined that thicker membrane materials

  7. Pulmonary neuroendocrine cells function as airway sensors to control lung immune response

    PubMed Central

    Branchfield, Kelsey; Nantie, Leah; Verheyden, Jamie M.; Sui, Pengfei; Wienhold, Mark D.; Sun, Xin

    2016-01-01

    The lung is constantly exposed to environmental atmospheric cues. How it senses and responds to these cues is poorly defined. Here, we show that Roundabout receptor (Robo) genes are expressed in pulmonary neuroendocrine cells (PNECs), a rare, innervated epithelial population. Robo inactivation in mouse lung results in an inability of PNECs to cluster into sensory organoids and triggers increased neuropeptide production upon exposure to air. Excess neuropeptides lead to an increase in immune infiltrates, which in turn remodel the matrix and irreversibly simplify the alveoli. We demonstrate in vivo that PNECs act as precise airway sensors that elicit immune responses via neuropeptides. These findings suggest that the PNEC and neuropeptide abnormalities documented in a wide array of pulmonary diseases may profoundly affect symptoms and progression. PMID:26743624

  8. Real time Measurement of Metabolic States in Living Cells using Genetically-encoded NADH Sensors

    PubMed Central

    Zhao, Yuzheng; Yang, Yi; Loscalzo, Joseph

    2014-01-01

    Redox metabolism plays critical roles in multiple biological processes and diseases. Until recently, knowledge of specific, key redox processes in living systems was limited by the lack of adequate methodology. Reduced nicotinamide adenine dinucleotide (NADH) and its oxidized form (NAD+) is the most important small molecule in the redox metabolism of mammalian cells. We previously reported a series of genetically encoded fluorescent sensors for intracellular NADH detection. Here, we present an accounting of experimental components and considerations, such as protein expression and purification, fluorescence titration, transfections, and confocal imaging, necessary to perform a standardized NADH assay experiment with these probes. In addition, we outline initial experiments used to derive basic principles of NADH/NAD+ redox biology in vitro. Finally, we describe a protocol for a steady-state kinetics experiment, and the processing of experimental data to measure intracellular NADH levels. PMID:24862275

  9. Measurement of in-plane elasticity of live cell layers using a pressure sensor embedded microfluidic device

    NASA Astrophysics Data System (ADS)

    Lin, Chien-Han; Wang, Chien-Kai; Chen, Yu-An; Peng, Chien-Chung; Liao, Wei-Hao; Tung, Yi-Chung

    2016-11-01

    In various physiological activities, cells experience stresses along their in-plane direction when facing substrate deformation. Capability of continuous monitoring elasticity of live cell layers during a period is highly desired to investigate cell property variation during various transformations under normal or disease states. This paper reports time-lapsed measurement of live cell layer in-plane elasticity using a pressure sensor embedded microfluidic device. The sensor converts pressure-induced deformation of a flexible membrane to electrical signals. When cells are cultured on top of the membrane, flexural rigidity of the composite membrane increases and further changes the output electrical signals. In the experiments, human embryonic lung fibroblast (MRC-5) cells are cultured and analyzed to estimate the in-plane elasticity. In addition, the cells are treated with a growth factor to simulate lung fibrosis to study the effects of cell transformation on the elasticity variation. For comparison, elasticity measurement on the cells by atomic force microscopy (AFM) is also performed. The experimental results confirm highly anisotropic configuration and material properties of cells. Furthermore, the in-plane elasticity can be monitored during the cell transformation after the growth factor stimulation. Consequently, the developed microfluidic device provides a powerful tool to study physical properties of cells for fundamental biophysics and biomedical researches.

  10. Measurement of in-plane elasticity of live cell layers using a pressure sensor embedded microfluidic device

    PubMed Central

    Lin, Chien-Han; Wang, Chien-Kai; Chen, Yu-An; Peng, Chien-Chung; Liao, Wei-Hao; Tung, Yi-Chung

    2016-01-01

    In various physiological activities, cells experience stresses along their in-plane direction when facing substrate deformation. Capability of continuous monitoring elasticity of live cell layers during a period is highly desired to investigate cell property variation during various transformations under normal or disease states. This paper reports time-lapsed measurement of live cell layer in-plane elasticity using a pressure sensor embedded microfluidic device. The sensor converts pressure-induced deformation of a flexible membrane to electrical signals. When cells are cultured on top of the membrane, flexural rigidity of the composite membrane increases and further changes the output electrical signals. In the experiments, human embryonic lung fibroblast (MRC-5) cells are cultured and analyzed to estimate the in-plane elasticity. In addition, the cells are treated with a growth factor to simulate lung fibrosis to study the effects of cell transformation on the elasticity variation. For comparison, elasticity measurement on the cells by atomic force microscopy (AFM) is also performed. The experimental results confirm highly anisotropic configuration and material properties of cells. Furthermore, the in-plane elasticity can be monitored during the cell transformation after the growth factor stimulation. Consequently, the developed microfluidic device provides a powerful tool to study physical properties of cells for fundamental biophysics and biomedical researches. PMID:27812019

  11. Pyruvate kinase isoenzyme M2 is a glycolytic sensor differentially regulating cell proliferation, cell size and apoptotic cell death dependent on glucose supply

    SciTech Connect

    Spoden, Gilles A.; Rostek, Ursula; Lechner, Stefan; Mitterberger, Maria; Mazurek, Sybille; Zwerschke, Werner

    2009-10-01

    The glycolytic key regulator pyruvate kinase M2 (M2-PK or PKM2) can switch between a highly active tetrameric and an inactive dimeric form. The transition between the two conformations regulates the glycolytic flux in tumor cells. We developed specific M2-PK-binding peptide aptamers which inhibit M2-PK, but not the 96% homologous M1-PK isoenzyme. In this study we demonstrate that, at normal blood glucose concentrations, peptide aptamer-mediated inhibition of M2-PK induces a significant decrease of the population doubling (PDL rate) and cell proliferation rate as well as an increase in cell size, whereas under glucose restriction an increase in PDL and cell proliferation rates but a decrease in cell size was observed. Moreover, M2-PK inhibition rescues cells from glucose starvation-induced apoptotic cell death by increasing the metabolic activity. These findings suggest that M2-PK is a metabolic sensor which regulates cell proliferation, cell growth and apoptotic cell death in a glucose supply-dependent manner.

  12. Genetically-encoded FRET-based sensors for monitoring Zn(2+) in living cells.

    PubMed

    Hessels, Anne M; Merkx, Maarten

    2015-02-01

    Genetically-encoded fluorescent sensor proteins are attractive tools for studying intracellular Zn(2+) homeostasis and signaling. Here we provide an overview of recently developed sensors based on Förster Resonance Energy Transfer (FRET). The pros and cons of the various sensors are discussed with respect to Zn(2+) affinity, dynamic range, intracellular targeting and multicolor imaging. Recent applications of these sensors are described, as well as some of the challenges that remain to be addressed in future research.

  13. Electrochemical sensors, MTT and immunofluorescence assays for monitoring the proliferation effects of cissus populnea extracts on Sertoli cells

    PubMed Central

    2011-01-01

    Background We describe the development of an electrochemical sensor array for monitoring the proliferation effects of cissus populnea plant extracts on TM4 Sertoli cells. Methods The proliferation activities of the extracts on Sertoli cells were studied using a high-throughput electrochemical sensor array (DOX-96) and the analytical sensor characteristics were compared with conventional colorimetric MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and fluorescence spectroscopy. Results This work shows that there is a definite positive trend in the proliferation effect of the extract of Cissus populnea on the TM4 Sertoli cells. All of the three techniques confirmed that the most effective concentration for the proliferation is 10 ppm. At this concentration, the proliferation effect was established around 120% for both DOX-96 and MTT techniques, whereas fluorescence assays showed a higher level (120-150%). DOX-96 showed a lower limit of detection (1.25 × 10(4) cells/ml); whereas the LOD recorded for both MTT and fluorescence techniques was 2.5 × 10(4) cells/ml. Visual examination of the cells by means of confocal fluorescence microscopy confirmed the proliferation of Sertoli cells as was determined using the MTT assay. This investigation provides a confident interpretation of the results and proved that the most effective concentration for the proliferation using Cissus populnea plant extract is 10 ppm. Conclusions Overall, the DOX results compared well with the conventional methods of checking proliferation of cells. The fascinating feature of the sensor array is the ability to provide continuous proliferation experiments with no additional reagents including 96 simultaneous electrochemical experiments. The use of the DOX-96 could reduce a typical bioassay time by 20-fold. Thus the DOX-96 can be used as both a research tool and for practical cell culture monitoring. PMID:21575213

  14. Real-time estimation of paracellular permeability of cerebral endothelial cells by capacitance sensor array

    NASA Astrophysics Data System (ADS)

    Hyun Jo, Dong; Lee, Rimi; Hyoung Kim, Jin; Oh Jun, Hyoung; Geol Lee, Tae; Hun Kim, Jeong

    2015-06-01

    Vascular integrity is important in maintaining homeostasis of brain microenvironments. In various brain diseases including Alzheimer’s disease, stroke, and multiple sclerosis, increased paracellular permeability due to breakdown of blood-brain barrier is linked with initiation and progression of pathological conditions. We developed a capacitance sensor array to monitor dielectric responses of cerebral endothelial cell monolayer, which could be utilized to evaluate the integrity of brain microvasculature. Our system measured real-time capacitance values which demonstrated frequency- and time-dependent variations. With the measurement of capacitance at the frequency of 100 Hz, we could differentiate the effects of vascular endothelial growth factor (VEGF), a representative permeability-inducing factor, on endothelial cells and quantitatively analyse the normalized values. Interestingly, we showed differential capacitance values according to the status of endothelial cell monolayer, confluent or sparse, evidencing that the integrity of monolayer was associated with capacitance values. Another notable feature was that we could evaluate the expression of molecules in samples in our system with the reference of real-time capacitance values. We suggest that this dielectric spectroscopy system could be successfully implanted as a novel in vitro assay in the investigation of the roles of paracellular permeability in various brain diseases.

  15. Distributed fiber-optic sensing in a high-temperature solid-oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Buric, M.; Ohodnicki, P.; Yan, A.; Huang, S.; Chen, K. P.

    2016-09-01

    High temperature solid-oxide fuel cells (SOFCs) present a challenging harsh environment for sensor systems with temperatures above 800C and ambient hydrogen concentration potentially ranging from 0-100% across the cell's anode. A strong gradient exists in both gas concentration and temperature from the fuel-inlet to outlet as fuel is consumed across the cell. We report a technique for measuring the spatial distribution of temperature along a solid-oxide fuel-cell interconnect channel using a distributed interrogation system coupled with a single-mode fiber optic thin-film evanescent wave absorption sensor. These sensors are to be operated inside an operating fuel-cell stack yielding spatially distributed measurements with sub-millimeter accuracy. Details are presented pertinent to the stable operation of silica optical fibers in the presence of high hydrogen concentration which can induce optical fiber losses. The stability of Rayleigh scattering centers is discussed with regard to the operational environment. The potential for extension of the approach to chemical (i.e. hydrogen) sensing as well as dual hydrogen/temperature sensor fabrication and stabilization are also briefly discussed.

  16. Investigation of biological cell-protein interactions using SPR sensor through laser scanning confocal imaging-surface plasmon resonance system

    NASA Astrophysics Data System (ADS)

    Zhang, Hongyan; Yang, Liquan; Zhou, Bingjiang; Wang, Xueliang; Liu, Guiying; Liu, Weimin; Wang, Pengfei

    2014-03-01

    A new method for investigating biological cell-protein interactions was developed by using a laser scanning confocal imaging-surface plasmon resonance (LSCI-SPR) system. Mouse normal IgG was modified on the SPR chip. The suspension mouse lymphocyte cancer cells (L5178Y cells) labeled by Hoechst33342 freely flowed into the surface of the SPR sensor chip. By changing the concentration of the cells, the fluorescence images and the SPR signal were synchronously recorded in real time. The red fluorescence points in the imaging region increased with increase in the concentration of the mouse lymphocyte cancer cells and fit well with the change in the SPR signal. Different suspending cells were chosen to investigate cell-protein interactions through antigen-antibody reactions on the biological cell surfaces through binding detection. This method has potential application in cell biology and pharmacology.

  17. Detection of bioavailable cadmium, lead, and arsenic in polluted soil by tailored multiple Escherichia coli whole-cell sensor set.

    PubMed

    Hou, Qihui; Ma, Anzhou; Wang, Thanh; Lin, Jianqiang; Wang, Hailin; Du, Binghai; Zhuang, Xuliang; Zhuang, Guoqiang

    2015-09-01

    Microbial whole-cell sensor has been widely used to assess bioavailability and risk of toxic elements, but their environmental use is still limited due to the presence of other interfering pollutants and the nonspecific binding in cells, which leads to inaccurate results. Here, we proposed a strategy combining Escherichia coli sensor set with binary regression models for the specific detection of bioavailable cadmium (Cd), lead (Pb), and arsenic (As) in a co-polluted environment. Initial tests suggested that the sensor set respectively termed pcadCluc, pzntRluc, and parsRluc could be classified into two groups according to their specific response to Cd, Pb, and As: group 1 (pcadCluc and pzntRluc) induced by a Cd-Pb mix and group 2 (parsRluc) induced by a Cd-As mix. Based on the variance in responses of each sensor to mixtures of target elements, three binary linear equations for two sensor groups were set up to calculate the individual concentrations in the mixture solutions. This method was then used to quantify the bioavailable Cd, Pb, and As in soils from a co-polluted mining region and to compare the results with other methods. Results showed that the conventional single target sensor method overestimated the bioavailability of each element, while sensor set was credible for accurate bioavailable Cd, Pb, and As quantification and comparable with the results from inductively coupled plasma mass spectrometry (ICP-MS) analysis. Our method can potentially be extended to cover the specific detection of other bioavailable toxic elements in different environmental settings.

  18. Microbial DNA recognition by cGAS-STING and other sensors in dendritic cells in inflammatory bowel diseases.

    PubMed

    Liu, Song; Zhang, Ying; Ren, Jianan; Li, Jieshou

    2015-04-01

    Recognition of microbial nucleic acid initiates host immune defenses against pathogens. Impaired recognition of nucleic acid is involved in the pathogenesis of inflammatory bowel diseases. In contrast to the relatively well-established mechanism of microbial RNA sensing and associated signaling cascades, very little is known on how microbial DNA activates intracellular DNA sensors and controls the function of antigen-presenting cells (especially dendritic cells) to shape mucosal immune responses in intestine. In this review, we will introduce mucosal dendritic cell population, describe various putative DNA sensors, emphasize on newly identified cGAS-cGAMP-STING complex, and discuss how the detection of foreign DNA by mucosal dendritic cells activates innate and adaptive immune responses in intestine. Finally, we will identify certain inflammatory bowel disease-susceptibility genes that associate with impaired microbial DNA recognition in human.

  19. Advances in using MRI probes and sensors for in vivo cell tracking as applied to regenerative medicine

    PubMed Central

    Srivastava, Amit K.; Kadayakkara, Deepak K.; Bar-Shir, Amnon; Gilad, Assaf A.; McMahon, Michael T.; Bulte, Jeff W. M.

    2015-01-01

    The field of molecular and cellular imaging allows molecules and cells to be visualized in vivo non-invasively. It has uses not only as a research tool but in clinical settings as well, for example in monitoring cell-based regenerative therapies, in which cells are transplanted to replace degenerating or damaged tissues, or to restore a physiological function. The success of such cell-based therapies depends on several critical issues, including the route and accuracy of cell transplantation, the fate of cells after transplantation, and the interaction of engrafted cells with the host microenvironment. To assess these issues, it is necessary to monitor transplanted cells non-invasively in real-time. Magnetic resonance imaging (MRI) is a tool uniquely suited to this task, given its ability to image deep inside tissue with high temporal resolution and sensitivity. Extraordinary efforts have recently been made to improve cellular MRI as applied to regenerative medicine, by developing more advanced contrast agents for use as probes and sensors. These advances enable the non-invasive monitoring of cell fate and, more recently, that of the different cellular functions of living cells, such as their enzymatic activity and gene expression, as well as their time point of cell death. We present here a review of recent advancements in the development of these probes and sensors, and of their functioning, applications and limitations. PMID:26035841

  20. Natural sequence variants of yeast environmental sensors confer cell-to-cell expression variability.

    PubMed

    Fehrmann, Steffen; Bottin-Duplus, Hélène; Leonidou, Andri; Mollereau, Esther; Barthelaix, Audrey; Wei, Wu; Steinmetz, Lars M; Yvert, Gaël

    2013-10-08

    Living systems may have evolved probabilistic bet hedging strategies that generate cell-to-cell phenotypic diversity in anticipation of environmental catastrophes, as opposed to adaptation via a deterministic response to environmental changes. Evolution of bet hedging assumes that genotypes segregating in natural populations modulate the level of intraclonal diversity, which so far has largely remained hypothetical. Using a fluorescent P(met17)-GFP reporter, we mapped four genetic loci conferring to a wild yeast strain an elevated cell-to-cell variability in the expression of MET17, a gene regulated by the methionine pathway. A frameshift mutation in the Erc1p transmembrane transporter, probably resulting from a release of laboratory strains from negative selection, reduced P(met17)-GFP expression variability. At a second locus, cis-regulatory polymorphisms increased mean expression of the Mup1p methionine permease, causing increased expression variability in trans. These results demonstrate that an expression quantitative trait locus (eQTL) can simultaneously have a deterministic effect in cis and a probabilistic effect in trans. Our observations indicate that the evolution of transmembrane transporter genes can tune intraclonal variation and may therefore be implicated in both reactive and anticipatory strategies of adaptation.

  1. Redesigned Gas Mass Flow Sensors for Space Shuttle Pressure Control System and Fuel Cell System

    NASA Technical Reports Server (NTRS)

    1996-01-01

    A program was conducted to determine if a state of the art micro-machined silicon solid state flow sensor could be used to replace the existing space shuttle orbiter flow sensors. The rather aggressive goal was to obtain a new sensor which would also be a multi-gas sensor and operate over a much wider flow range and with a higher degree of accuracy than the existing sensors. Two types of sensors were tested. The first type was a venturi throat design and the second was a bypass design. The accuracy of venturi design was found to be marginally acceptable. The bypass sensor was much better although it still did not fully reach the accuracy goal. Two main problems were identified which would require further work.

  2. Photoelectron Spectroscopy of CdSe Nanocrystals in the Gas Phase: A Direct Measure of the Evanescent Electron Wave Function of Quantum Dots

    DTIC Science & Technology

    2013-01-01

    Spectroscopy of CdSe Nanocrystals in the Gas Phase: A Direct Measure of the Evanescent Electron Wave Function of Quantum Dots Wei Xiong...the fraction of evanescent electron wave function that extends outside of the quantum dot . This work shows that gas-phase photoelectron spectroscopy ...function. KEYWORDS: Quantum dots , ultrafast, electronic structure, aerodynamic lens, gas phase photoelectron spectroscopy , velocity map imaging Quantum

  3. Tools for water quality monitoring and mapping using paper-based sensors and cell phones.

    PubMed

    Sicard, Clémence; Glen, Chad; Aubie, Brandon; Wallace, Dan; Jahanshahi-Anbuhi, Sana; Pennings, Kevin; Daigger, Glen T; Pelton, Robert; Brennan, John D; Filipe, Carlos D M

    2015-03-01

    In this paper we describe a combination of paper-based sensors and a novel smart-phone application for on-site quantification of colorimetric readouts as an ultra-low cost solution to monitoring water quality. The system utilizes a paper-based analytical device (μPAD) that produces a colorimetric signal that is dependent on the concentration of a specific target; a cell phone equipped with a camera for capturing images of two μPADs - one tested with a water sample and the other tested with clean water that is used as a control; and an on-site image processing app that uses a novel algorithm for quantifying color intensity and relating this to contaminant concentration. The cell phone app utilizes a pixel counting algorithm that performs with less bias and user subjectivity than the typically used lab-based software, ImageJ. The use of a test and control strip reduces bias from variations in ambient lighting, making it possible to acquire and process images on-site. The cell phone is also able to GPS tag the location of the test, and transmit results to a newly developed website, WaterMap.ca, that displays the quantitative results from the water samples on a map. We demonstrate our approach using a previously developed μPAD that detects the presence of organophosphate pesticides based on the inhibition of immobilized acetylcholinesterase by these contaminants. The objective of this paper is to highlight the importance and potential of developing and integrated monitoring system consisting of μPADs, cell-phones and a centralized web portal for low-cost monitoring environmental contaminants at a large-scale.

  4. Functional micro/nanostructures: simple synthesis and application in sensors, fuel cells, and gene delivery.

    PubMed

    Guo, Shaojun; Wang, Erkang

    2011-07-19

    In order to develop new, high technology devices for a variety of applications, researchers would like to better control the structure and function of micro/nanomaterials through an understanding of the role of size, shape, architecture, composition, hybridization, molecular engineering, assembly, and microstructure. However, researchers continue to face great challenges in the construction of well-defined micro/nanomaterials with diverse morphologies. At the same time, the research interface where micro/nanomaterials meet electrochemistry, analytical chemistry, biomedicine, and other fields provides rich opportunities to reveal new chemical, physical, and biological properties of micro/nanomaterials and to uncover many new functions and applications of these materials. In this Account, we describe our recent progress in the construction of novel inorganic and polymer nanostructures formed through different simple strategies. Our synthetic strategies include wet-chemical and electrochemical methods for the controlled production of inorganic and polymer nanomaterials with well-defined morphologies. These methods are both facile and reliable, allowing us to produce high-quality micro/nanostructures, such as nanoplates, micro/nanoflowers, monodisperse micro/nanoparticles, nanowires, nanobelts, and polyhedron and even diverse hybrid structures. We implemented a series of approaches to address the challenges in the preparation of new functional micro/nanomaterials for a variety of important applications This Account also highlights new or enhanced applications of certain micro/nanomaterials in sensing applications. We singled out analytical techniques that take advantage of particular properties of micro/nanomaterials. Then by rationally tailoring experimental parameters, we readily and selectively obtained different types of micro/nanomaterials with novel morphologies with high performance in applications such as electrochemical sensors, electrochemiluminescent sensors

  5. Design of solid-core microstructured optical fiber with steering-wheel air cladding for optimal evanescent-field sensing.

    PubMed

    Zhu, Yinian; Du, Henry; Bise, Ryan

    2006-04-17

    We present the design of a solid-core microstructured optical fiber with steering-wheel pattern of large holes in cladding as platform for evanescent-field sensing. Both geometry and optical properties of the fiber are numerical computed and analyzed in consideration of manufacturability using sol-gel casting technique as well as by evaluating a triangular lattice of holes with three rings in the design structure so that effective parameters can be established using effective step-index model. We predict less than 0.7 dB/m confinement loss at 850 nm, 29%, 13.7%, and 7.2% of light intensity overlap in air holes at 1500 nm, 1000 nm, and 850 nm wavelength, respectively, in such fiber. With the low loss and high mode-field overlap, the steering-wheel structured fiber is well suited for evanescent-field sensing and detection of chemical and biological species.

  6. Detection of breast cancer cells using targeted magnetic nanoparticles and ultra-sensitive magnetic field sensors

    PubMed Central

    2011-01-01

    Introduction Breast cancer detection using mammography has improved clinical outcomes for many women, because mammography can detect very small (5 mm) tumors early in the course of the disease. However, mammography fails to detect 10 - 25% of tumors, and the results do not distinguish benign and malignant tumors. Reducing the false positive rate, even by a modest 10%, while improving the sensitivity, will lead to improved screening, and is a desirable and attainable goal. The emerging application of magnetic relaxometry, in particular using superconducting quantum interference device (SQUID) sensors, is fast and potentially more specific than mammography because it is designed to detect tumor-targeted iron oxide magnetic nanoparticles. Furthermore, magnetic relaxometry is theoretically more specific than MRI detection, because only target-bound nanoparticles are detected. Our group is developing antibody-conjugated magnetic nanoparticles targeted to breast cancer cells that can be detected using magnetic relaxometry. Methods To accomplish this, we identified a series of breast cancer cell lines expressing varying levels of the plasma membrane-expressed human epidermal growth factor-like receptor 2 (Her2) by flow cytometry. Anti-Her2 antibody was then conjugated to superparamagnetic iron oxide nanoparticles using the carbodiimide method. Labeled nanoparticles were incubated with breast cancer cell lines and visualized by confocal microscopy, Prussian blue histochemistry, and magnetic relaxometry. Results We demonstrated a time- and antigen concentration-dependent increase in the number of antibody-conjugated nanoparticles bound to cells. Next, anti Her2-conjugated nanoparticles injected into highly Her2-expressing tumor xenograft explants yielded a significantly higher SQUID relaxometry signal relative to unconjugated nanoparticles. Finally, labeled cells introduced into breast phantoms were measured by magnetic relaxometry, and as few as 1 million labeled cells

  7. Optical response of magnetic fluorescent microspheres used for force spectroscopy in the evanescent field.

    PubMed

    Bijamov, Alex; Shubitidze, Fridon; Oliver, Piercen M; Vezenov, Dmitri V

    2010-07-20

    Force spectroscopy based on magnetic tweezers is a powerful technique for manipulating single biomolecules and studying their interactions. The resolution in magnetic probe displacement, however, needs to be commensurate with molecular sizes. To achieve the desirable sensitivity in tracking displacements of the magnetic probe, some recent approaches have combined magnetic tweezers with total internal reflection fluorescence microscopy. In this situation, a typical force probe is a polymer microsphere containing two types of optically active components: a pure absorber (magnetic nanoparticles for providing the pulling force) and a luminophore (semiconducting nanoparticles or organic dyes for fluorescent imaging). To assess the system's capability fully with regard to tracking the position of the force probe with subnanometer accuracy, we developed a body-of-revolution formulation of the method of auxiliary sources (BOR-MAS) to simulate the absorption, scattering, and fluorescence of microscopic spheres in an evanescent electromagnetic field. The theoretical formulation uses the axial symmetry of the system to reduce the dimensionality of the modeling problem and produces excellent agreement with the reported experimental data on forward scattering intensity. Using the BOR-MAS numerical model, we investigated the probe detection sensitivity for a high numerical aperture objective. The analysis of both backscattering and fluorescence observation modes shows that the total intensity of the bead image decays exponentially with the distance from the surface (or the length of a biomolecule). Our investigations demonstrate that the decay lengths of observable optical power are smaller than the penetration depth of the unperturbed excitation evanescent wave. In addition, our numerical modeling results illustrate that the expected sensitivity for the decay length changes with the angle of incidence, tracking the theoretical penetration depth for a two-media model, and is

  8. Size-based cell sorting with a resistive pulse sensor and an electromagnetic pump in a microfluidic chip.

    PubMed

    Song, Yongxin; Li, Mengqi; Pan, Xinxiang; Wang, Qi; Li, Dongqing

    2015-02-01

    An electrokinetic microfluidic chip is developed to detect and sort target cells by size from human blood samples. Target-cell detection is achieved by a differential resistive pulse sensor (RPS) based on the size difference between the target cell and other cells. Once a target cell is detected, the detected RPS signal will automatically actuate an electromagnetic pump built in a microchannel to push the target cell into a collecting channel. This method was applied to automatically detect and sort A549 cells and T-lymphocytes from a peripheral fingertip blood sample. The viability of A549 cells sorted in the collecting well was verified by Hoechst33342 and propidium iodide staining. The results show that as many as 100 target cells per minute can be sorted out from the sample solution and thus is particularly suitable for sorting very rare target cells, such as circulating tumor cells. The actuation of the electromagnetic valve has no influence on RPS cell detection and the consequent cell-sorting process. The viability of the collected A549 cell is not impacted by the applied electric field when the cell passes the RPS detection area. The device described in this article is simple, automatic, and label-free and has wide applications in size-based rare target cell sorting for medical diagnostics.

  9. Highly Stretchable Fully-Printed CNT-based Electrochemical Sensors and Biofuel Cells: Combining Intrinsic and Design-induced Stretchability

    PubMed Central

    Bandodkar, Amay J.; Jeerapan, Itthipon; You, Jung-Min; Nuñez-Flores, Rogelio; Wang, Joseph

    2015-01-01

    We present the first example of an all-printed, inexpensive, highly stretchable CNT-based electrochemical sensor and biofuel cell array. The synergistic effect of utilizing specially tailored screen printable stretchable inks that combine the attractive electrical and mechanical properties of CNTs with the elastomeric properties of polyurethane as a binder along with a judiciously designed free-standing serpentine pattern enables the printed device to possess two degrees of stretchability. Owing to these synergistic design and nanomaterial-based ink effects, the device withstands extremely large levels of strains (upto 500% strain) with negligible effect on its structural integrity and performance. This represents the highest stretchability offered by a printed device reported to date. Extensive electrochemical characterization of the printed device reveal that repeated stretching, torsional twisting and indenting stress has negligible impact on its electrochemical properties. The wide-range applicability of this platform to realize highly stretchable CNT-based electrochemical sensors and biofuel cells has been demonstrated by fabricating and characterizing potentiometric ammonium sensor, amperometric enzyme-based glucose sensor, enzymatic glucose biofuel cell and self-powered biosensor. Highly stretchable printable multi-analyte sensor, multi-fuel biofuel cell or any combination thereof can thus be realized using the printed CNT array. Such combination of intrinsically-stretchable printed nanomaterial-based electrodes and strain-enduring design patterns holds considerable promise for creating an attractive class of inexpensive multi-functional, highly stretchable printed devices that satisfy the requirements of diverse healthcare and energy fields wherein resilience towards extreme mechanical deformations is mandatory. PMID:26694819

  10. Intrinsic Fabry-Perot optical fiber sensors and their multiplexing

    DOEpatents

    Wang, Anbo

    2007-12-11

    An intrinsic Fabry-Perot optical sensor includes a thin film sandwiched between two fiber ends. When light is launched into the fiber, two reflections are generated at the two fiber/thin film interfaces due to a difference in refractive indices between the fibers and the film, giving rise to the sensor output. In another embodiment, a portion of the cladding of a fiber is removed, creating two parallel surfaces. Part of the evanescent fields of light propagating in the fiber is reflected at each of the surfaces, giving rise to the sensor output. In a third embodiment, the refractive index of a small portion of a fiber is changed through exposure to a laser beam or other radiation. Interference between reflections at the ends of the small portion give rise to the sensor output. Multiple sensors along a single fiber are multiplexed using an optical time domain reflectometry method.

  11. Quantifying oxygen in paper-based cell cultures with luminescent thin film sensors.

    PubMed

    Boyce, Matthew W; Kenney, Rachael M; Truong, Andrew S; Lockett, Matthew R

    2016-04-01

    Paper-based scaffolds are an attractive material for generating 3D tissue-like cultures because paper is readily available and does not require specialized equipment to pattern, cut, or use. By controlling the exchange of fresh culture medium with the paper-based scaffolds, we can engineer diffusion-dominated environments similar to those found in spheroids or solid tumors. Oxygen tension directly regulates cellular phenotype and invasiveness through hypoxia-inducible transcription factors and also has chemotactic properties. To date, gradients of oxygen generated in the paper-based cultures have relied on cellular response-based readouts. In this work, we prepared a luminescent thin film capable of quantifying oxygen tensions in apposed cell-containing paper-based scaffolds. The oxygen sensors, which are polystyrene films containing a Pd(II) tetrakis(pentafluorophenyl)porphyrin dye, are photostable, stable in culture conditions, and not cytotoxic. They have a linear response for oxygen tensions ranging from 0 to 160 mmHg O2, and a Stern-Volmer constant (K sv) of 0.239 ± 0.003 mmHg O2 (-1). We used these oxygen-sensing films to measure the spatial and temporal changes in oxygen tension for paper-based cultures containing a breast cancer line that was engineered to constitutively express a fluorescent protein. By acquiring images of the oxygen-sensing film and the fluorescently labeled cells, we were able to approximate the oxygen consumption rates of the cells in our cultures.

  12. Experimental verification of an exact evanescent light scattering model for TIRM.

    PubMed

    Hertlein, Christopher; Riefler, Norbert; Eremina, Elena; Wriedt, Thomas; Eremin, Yuri; Helden, Laurent; Bechinger, Clemens

    2008-01-01

    Total internal reflection microscopy (TIRM) is a method for the precise measurement of interaction potentials between a spherical colloidal particle and a wall. The method is based on single-particle evanescent wave light scattering. The well-established model used to interpret TIRM data is based on an exponential relation between scattering intensity and particle wall distance. However, applying this model for a certain range of experimental parameters leads to significant distortions of the measured potentials. Using a TIRM setup based on a two-wavelength illumination technique, we were able to directly measure the intensity distance relation revealing deviations from an exponential decay. The intensity-distance relations could be compared to scattering simulations taking into account exact experimental parameters and multiple reflections between a particle and the wall. Converging simulation results were independently obtained by the T-matrix method and the discrete sources method (DSM) and show excellent agreement with experiments. Using the new scattering model for data evaluation, we could reconstruct the correct potential shape for distorted interaction potentials as we demonstrate. The comparison of simulations to experiment intrinsically yields a new method to determine absolute particle-wall distances, a highly desired quantity in TIRM experiments.

  13. Evanescent coupling of asymmetric self-rolled-up microtube and slab waveguide

    NASA Astrophysics Data System (ADS)

    Sedaghat, Setareh; Zarifkar, Abbas

    2017-01-01

    In this paper, for the first time, optical characteristics of asymmetric self-rolled-up microtube (SRM) are investigated analytically. By considering the asymmetric nature of SRM, modified conformal mapping method is introduced to derive closed-form formulas for resonant modes and field profiles. Intrinsic quality factor (Q-factor), due to whispering gallery and edge scattering losses, is evaluated by combining modified conformal mapping and volume current methods. Also, coupling strength and consequently external Q-factor for evanescent coupling of asymmetric SRM and silicon (Si) slab waveguide is theoretically examined by the coupled mode theory. The simulations show that tailoring the design parameters such as radius of SRM, winding number and asymmetric parameter severely affects the resonant modes and each constituent of Q-factor. On the other hand, Q-factor of edge scattering ( 3×106) determines the limit for intrinsic Q-factor. Additionally, the impact of phase mismatch and field overlap on external Q-factor is investigated when the height of Si waveguide and the gap distance between SRM and Si waveguide are changed. Results are in good agreement with the numerical simulation values and the data extracted from experimental reports.

  14. Evanescent wave absorption measurements of corroded materials using ATR and optical fibers

    NASA Astrophysics Data System (ADS)

    Namkung, Juock; Hoke, Mike; Schwartz, Andy

    2011-06-01

    The purpose of this research effort is to develop an in-situ corrosion sensing capability. The technique will permit detection of corrosion on and within aircraft structures. This includes component junctions that are susceptible to corrosion but which are not accessible for visual inspection. The prototype experimental configuration we are developing includes long wave infrared transmitting optical fiber probes interfaced with a Fourier Transform Infrared (FTIR) interferometer for evanescent wave absorption spectroscopic measurements. The mature and fielded technique will allow periodic remote sensing for detection of corrosion and for general onboard aircraft structural health monitoring. An experimental setup using an Attenuated Total Reflection (ATR) crystal integrated with an FTIR spectrometer has been assembled. Naturally occurring corrosion including Aluminum Hydroxide [Al(OH)3] is one of the main corrosion products of aluminum the principle structural metal of aircraft. Absorption spectra of our model corrosion product, pure Al(OH)3, have been collected with this ATR/FTIR experimental setup. The Al(OH)3spectra serve as reference spectral signatures. The spectra of corrosion samples from a simulated corrosion process have been collected and compared with the reference Al(OH)3 spectra. Also absorption spectra of naturally occurring corrosion collected from a fielded corroded aircraft part have been obtained and compared with the spectra from the simulated corrosion.

  15. Ultra-sensitive plasmonic nanometal scattering immunosensor based on optical control in the evanescent field layer.

    PubMed

    Lee, Seungah; Park, Guenyoung; Chakkarapani, Suresh Kumar; Kang, Seong Ho

    2015-01-15

    Novel, fluorescence-free detection of biomolecules on nanobiochips was investigated based on plasmonic nanometal scattering in the evanescent field layer (EFL) using total internal reflection scattering (TIRS) microscopy. The plasmonic scattering of nanometals bonded to biomolecules was observed at different wavelengths by an electromagnetic field in the EFL. The changes in the scattering of nanometals on the gold-nanopatterned chip in response to the immunoreaction between silver nanoparticles and antibodies allowed fluorescence-free detection of biomolecules on the nanobiochips. Under optimized conditions, the TIRS immunoassay chip detected different amounts of immobilized antigen, i.e., human cardiac troponin I. The sandwich immuno-reaction was quantitatively analyzed in the dynamic range of 720 zM-167 fM. The limit of detection (S/N=4) was 600 zM, which was ~140 times lower than limits obtained by previous total internal reflection fluorescence and dark field methods. These results demonstrate the possibility for a fluorescence-free biochip nanoimmunoassay based on the scattering of nanometals in the EFL.

  16. Cancer diagnostics using Fourier transform fiber optic infrared evanescent wave spectroscopy (FTIR-FEWS)

    NASA Astrophysics Data System (ADS)

    Spielvogel, Juergen; Lobik, Leonid; Nissencorn, Israel; Hibst, Raimund; Gotshal, Yaron; Katzir, Abraham

    1998-06-01

    A Fourier transform IR spectrometer and IR transmitting AgClBr fibers were used for fiberoptic evanescent wave spectroscopy (FTIR-FEWS) of cancer. Malignant and healthy tissue samples were extracted from patients at the Meir Hospital in Israel, placed on a Silver Halide fiber, and measured using the FTIR-FEWS system. The IR spectra were analyzed and compared by taking the ratio of absorption of the active functional groups of Amide I at 1642 cm-1 and Amide II at 1545 cm-1. Clear differences appeared between the two types of tissue. When placing the tissue samples on bare fiber the reproducibility of the result was not satisfactory due to chemical interaction between the tissue and the fibers. This problem was solved by applying Polyethylene coating of thickness 1-2 μm on the fiber, leading to reproducible results. The results of these preliminary studies indicate that eh FTIR-FEWS technique can be used for cancer diagnostics. Combined with endoscopy this technique could be used to analyze tissues inside the body in vivo and in real time.

  17. Bond characterization by detection and manipulation of particle mobility in an optical evanescent field biosensor

    NASA Astrophysics Data System (ADS)

    van Ommering, Kim; Koets, Marjo; Paesen, Rik; van IJzendoorn, Leo J.; Prins, Menno W. J.

    2010-09-01

    We present an optical biosensor technology that integrates the tethered particle motion technique and the magnetic tweezer technique. The goal is to quantify the three-dimensional mobility of bound particle labels and to characterize the bond between the particle and the surface. We show, using a series of four different lengths of dsDNA (105-590 bp), that plots of the height as a function of the in-plane particle position reflect the bond length and bond flexibility. We analyse ensembles of bound particles and show that the height displacement is at maximum the bond length, but that non-specific sticking causes large variations between particles. We also measured the height of bound particles under the influence of magnetic forces. A magnetic gradient force towards the surface brought particles on average closer to the surface, but a magnetic gradient force away from the surface did not bring all particles away from the surface. We show that the latter can be explained by magnetic anisotropy in the particles. Our results demonstrate that mobility detection of bound particle labels in an evanescent field is a promising technique to characterize the bond between a particle and a surface in a biosensor system.

  18. Evanescent wave and video microscopy methods for directly measuring interactions between surface-immobilized biomolecules

    NASA Astrophysics Data System (ADS)

    Everett, William Neil

    Spatial and temporal tracking of passively diffusing functionalized colloids continues to be an improving and auspicious approach to measuring weak specific and non-specific biomolecular interactions. Evidence of this is given by the recent increase in published studies involving the development and implementation of these methods. The primary aim of the work presented in this dissertation was to modify and optimize video microscopy (VM) and total internal reflection microscopy (TIRM) methods to permit the collection of equilibrium binding and sampling data from interaction of surface-immobilized biomolecules. Supported lipid bilayers were utilized as model systems for functionalizing colloid and wall surfaces. Preliminary results measuring calcium-specific protein-protein interactions between surface immobilized cadherin fragments demonstrate the potential utility of this experimental system and these methods. Additionally, quantum dot-modified colloids were synthesized and evanescent wave-excited luminescence from these particles was used to construct potential energy profiles. Results from this work demonstrate that colloids can be used as ultra-sensitive probes of equilibrium interactions between biomolecules, and specialized probes, such as those modified with quantum dots, could be used in a spectral multiplexing mode to simultaneously monitor multiple interactions.

  19. Infrared fiber optic evanescent wave spectroscopy: applications in biology and medicine

    NASA Astrophysics Data System (ADS)

    Afanasyeva, Natalia I.; Bruch, Reinhard F.; Katzir, Abraham

    1999-04-01

    A new powerful and highly sensitive technique for non-invasive biomedical diagnostics in vivo has been developed using Infrared Fiberoptic Evanescent Wave Fourier Transform Spectroscopy (FEW-FTIR). This compact and portable method allows to detect functional chemical groups and bonds via vibrational spectroscopy directly from surfaces including living tissue. Such differences and similarities in molecular structure of tissue and materials can be evaluated online. Operating in the attenuated total reflection (ATR) regime in the middle-infrared (MIR) range, the FEW-FTIR technique provides direct contact between the fiber probe and tissue for non-destructive, non-invasive, fast and remote (few meters) diagnostics and quality control of materials. This method utilizes highly flexible and extremely low loss unclad fibers, for example silver halide fibers. Applications of this method include investigations of normal skin, precancerous and cancerous conditions, monitoring of the process of aging, allergic reactions and radiation damage to the skin. This setup is suitable as well for the detection of the influence of environmental factors (sun, water, pollution, and weather) on skin surfaces. The FEW-FTIR technique is very promising also for fast histological examinations in vitro. In this review, we present recent investigations of skin, breast, lung, stomach, kidney tissues in vivo and ex vivo (during surgery) to define the areas of tumor localization. The main advantages of the FEW-FTIR technique for biomedical, clinical, and environmental applications are discussed.

  20. Diblock copolymer adsorption onto a solid surface as revealed by evanescent wave ellipsometry

    SciTech Connect

    Kim, M.W. ); Russell, T.P. . Almaden Research Center); Moses, T.; Chen, W.; Shen, Y.R. . Center for Advanced Materials Univ. of California, Berkeley, CA . Dept. of Physics)

    1994-12-05

    The interfacial behavior of diblock copolymers play an important role in many practical applications, for example, polymer compatibilization, adhesion, and colloid stabilization. There has been considerable theoretical and experimental effort to understand the adsorption behavior of diblock copolymers from a solution onto a solid surface. Recent neutron reflectivity measurements on solutions of symmetric diblock copolymers of polystyrene and poly(methyl methacrylate), denoted P(S-b-MMA), near a quartz wall have shown that the PMMA segments adsorb preferentially onto the quartz forming a dense layer. However, the segmental concentration of polystyrene (PS) was too low to be observable. Evanescent wave ellipsometry, EWE, on the other hand, allows one to determine the density of molecules adsorbed onto a surface without labeling the segments with deuterium. Here, EWE results on P(S-b-MMA) adsorbed onto a solid substrate are presented as a function of molecular weight. It is shown that the adsorbed amount of copolymer is maximized for a particular molecular weight. This result contradicts theoretical predictions, and a possible origin of this discrepancy is provided.

  1. Fabrication of D-type fiber optic sensors with a long interaction length and studying effects of critical parameters on sensor response

    NASA Astrophysics Data System (ADS)

    Guleryuz, Burcu; Durucan, Caner; Aslan, Mustafa M.

    2014-05-01

    Today evanescent wave based fiber optic (F/O) platforms are in favor of the use for monitoring molecular interactions since they are practical, economic and easy to operate which make them ideal turnkey systems for clinical, pharmaceutical, environmental and security applications. The side polishing is one of techniques for reshaping the geometry of the waveguide to make the F/O sensor more sensitive to surrounding refractive index (RI) in evanescent field. In this study D-type F/O sensors with a 25 mm-long interaction lengths are fabricated. In addition to that, effects of the critical parameters such as the polishing depth, the wavelength, and the temperature on the sensor response are determined for the RI in the range of 1.33 - 1.47. The developing key of these F/O sensors is reaching high strength and penetration depth of evanescent wave in varying RI of the surrounding bio-layer. Development steps of D-type F/O sensors are; fabrication of supporting elements - silicon V channels, F/O cable preparation, adhesion, lapping and polishing, fusing the FC connectors, construction of the optical system, and RI measurements. Details of these steps are explained and the general characteristics of the D-type F/O sensor are presented. Results indicate that the sensor's responses in three different RI ranges can be improved by the polishing depth. A maximum sensitivity of around 2x105 for the D-type F/O sensors is demonstrated in the RI range of 1.44-1.46.

  2. Nanoparticle-Based and Bioengineered Probes and Sensors to Detect Physiological and Pathological Biomarkers in Neural Cells.

    PubMed

    Maysinger, Dusica; Ji, Jeff; Hutter, Eliza; Cooper, Elis

    2015-01-01

    Nanotechnology, a rapidly evolving field, provides simple and practical tools to investigate the nervous system in health and disease. Among these tools are nanoparticle-based probes and sensors that detect biochemical and physiological properties of neurons and glia, and generate signals proportionate to physical, chemical, and/or electrical changes in these cells. In this context, quantum dots (QDs), carbon-based structures (C-dots, grapheme, and nanodiamonds) and gold nanoparticles are the most commonly used nanostructures. They can detect and measure enzymatic activities of proteases (metalloproteinases, caspases), ions, metabolites, and other biomolecules under physiological or pathological conditions in neural cells. Here, we provide some examples of nanoparticle-based and genetically engineered probes and sensors that are used to reveal changes in protease activities and calcium ion concentrations. Although significant progress in developing these tools has been made for probing neural cells, several challenges remain. We review many common hurdles in sensor development, while highlighting certain advances. In the end, we propose some future directions and ideas for developing practical tools for neural cell investigations, based on the maxim "Measure what is measurable, and make measurable what is not so" (Galileo Galilei).

  3. Continuous oxygen monitoring of mammalian cell growth on space shuttle mission STS-93 with a novel radioluminescent oxygen sensor.

    PubMed

    Reece, Julie S; Miller, Michael J; Arnold, Mark A; Waterhouse, Cris; Delaplaine, Ted; Cohn, Laura; Cannon, Tom

    2003-01-01

    A compact, flow-through oxygen sensor device based on luminescence quenching was used to monitor dissolved oxygen levels during mammalian cell growth on the STS-93 mission of the Columbia space shuttle. Excitation of an oxygen-sensitive ruthenium complex was provided by a radioluminescent light source (0.9 mm in diameter, 2.5 mm long), and the intensity of the resulting luminescence was measured by a simple photodiode detector. The use of radioluminescence for the excitation light source is a unique approach that provides many features important for long-term and remote monitoring applications. For the spaceflight experiment, human lung fibroblast cells (WI-38) were grown in hollow-fiber bioreactors. Oxygen concentration was measured in the flow path both before and after the bioreactor cartridge in order to gain information about the metabolism of the cells. The sensor was found to be nonperturbing to cell growth and withstood the challenging physical conditions of shuttle launch and landing while maintaining a stable calibration function. In addition, the sensor provided physically meaningful oxygen predictions.

  4. Nanoparticle-Based and Bioengineered Probes and Sensors to Detect Physiological and Pathological Biomarkers in Neural Cells

    PubMed Central

    Maysinger, Dusica; Ji, Jeff; Hutter, Eliza; Cooper, Elis

    2015-01-01

    Nanotechnology, a rapidly evolving field, provides simple and practical tools to investigate the nervous system in health and disease. Among these tools are nanoparticle-based probes and sensors that detect biochemical and physiological properties of neurons and glia, and generate signals proportionate to physical, chemical, and/or electrical changes in these cells. In this context, quantum dots (QDs), carbon-based structures (C-dots, grapheme, and nanodiamonds) and gold nanoparticles are the most commonly used nanostructures. They can detect and measure enzymatic activities of proteases (metalloproteinases, caspases), ions, metabolites, and other biomolecules under physiological or pathological conditions in neural cells. Here, we provide some examples of nanoparticle-based and genetically engineered probes and sensors that are used to reveal changes in protease activities and calcium ion concentrations. Although significant progress in developing these tools has been made for probing neural cells, several challenges remain. We review many common hurdles in sensor development, while highlighting certain advances. In the end, we propose some future directions and ideas for developing practical tools for neural cell investigations, based on the maxim “Measure what is measurable, and make measurable what is not so” (Galileo Galilei). PMID:26733793

  5. Development of cell-based quantitative evaluation method for cell cycle-arrest type cancer drugs for apoptosis by high precision surface plasmon resonance sensor

    NASA Astrophysics Data System (ADS)

    Ona, Toshihiro; Nishijima, Hiroshi; Kosaihira, Atsushi; Shibata, Junko

    2008-04-01

    In vitro rapid and quantitative cell-based assay is demanded to verify the efficacy prediction of cancer drugs since a cancer patient may have unconventional aspects of tumor development. Here, we show the rapid and non-label quantitative verifying method and instrumentation of apoptosis for cell cycle-arrest type cancer drugs (Roscovitine and D-allose) by reaction analysis of living liver cancer cells cultured on a sensor chip with a newly developed high precision (50 ndeg s -1 average fluctuation) surface plasmon resonance (SPR) sensor. The time-course cell reaction as the SPR angle change rate for 10 min from 30 min cell culture with a drug was significantly related to cell viability. By the simultaneous detection of differential SPR angle change and fluorescence by specific probes using the new instrument, the SPR angle was related to the nano-order potential decrease in inner mitochondrial membrane potential. The results obtained are universally valid for the cell cycle-arrest type cancer drugs, which mediate apoptosis through different cell-signaling pathways, by a liver cancer cell line of Hep G2 (P<0.001). This system towards the application to evaluate personal therapeutic potentials of drugs using cancer cells from patients in clinical use.

  6. Osmotic induction of calcium accumulation in human embryonic kidney cells detected with a high sensitivity FRET calcium sensor.

    PubMed

    Hou, Bi-Huei; Takanaga, Hitomi; Griesbeck, Oliver; Frommer, Wolf B

    2009-08-01

    Calcium serves as a second messenger in glucose-triggered insulin secretion of pancreatic cells. Less is known about sugar signaling in non-excitable cells. Here, the high sensitivity FRET calcium sensor TN-XXL was used to characterize glucose-induced calcium responses in non-excitable human embryonic kidney HEK293T cells. HEK293T cells responded to perfusion with glucose with a sustained and concentration-dependent increase in cytosolic calcium levels. Sucrose and mannitol triggered comparable calcium responses, suggesting that the increase of the calcium concentration was caused by osmotic effects. HEK293T cells are characterized by low endogenous glucose uptake capacity as shown with a high sensitivity glucose sensor. Consistently, when glucose influx was artificially increased by co-expression of GLUT glucose transporters, the glucose-induced calcium increase was significantly reduced. Neither calcium depletion, nor gadolinium or thapsigargin were able to inhibit the calcium accumulation. Taken together, membrane impermeable osmolytes such as sucrose and mannitol lead to an increase in calcium levels, while the effect of glucose depends on the cell's glucose uptake capacity and will thus vary between cell types in the body that differ in their glucose uptake capacity.

  7. Microbial nar-GFP cell sensors reveal oxygen limitations in highly agitated and aerated laboratory-scale fermentors

    PubMed Central

    Garcia, Jose R; Cha, Hyung J; Rao, Govind; Marten, Mark R; Bentley, William E

    2009-01-01

    Background Small-scale microbial fermentations are often assumed to be homogeneous, and oxygen limitation due to inadequate micromixing is often overlooked as a potential problem. To assess the relative degree of micromixing, and hence propensity for oxygen limitation, a new cellular oxygen sensor has been developed. The oxygen responsive E. coli nitrate reductase (nar) promoter was used to construct an oxygen reporter plasmid (pNar-GFPuv) which allows cell-based reporting of oxygen limitation. Because there are greater than 109 cells in a fermentor, one can outfit a vessel with more than 109 sensors. Our concept was tested in high density, lab-scale (5 L), fed-batch, E. coli fermentations operated with varied mixing efficiency – one verses four impellers. Results In both cases, bioreactors were maintained identically at greater than 80% dissolved oxygen (DO) during batch phase and at approximately 20% DO during fed-batch phase. Trends for glucose consumption, biomass and DO showed nearly identical behavior. However, fermentations with only one impeller showed significantly higher GFPuv expression than those with four, indicating a higher degree of fluid segregation sufficient for cellular oxygen deprivation. As the characteristic time for GFPuv expression (approx 90 min.) is much larger than that for mixing (approx 10 s), increased specific fluorescence represents an averaged effect of oxygen limitation over time and by natural extension, over space. Conclusion Thus, the pNar-GFPuv plasmid enabled bioreactor-wide oxygen sensing in that bacterial cells served as individual recirculating sensors integrating their responses over space and time. We envision cell-based oxygen sensors may find utility in a wide variety of bioprocessing applications. PMID:19146688

  8. Real time monitoring of the effects of Heparan Sulfate Proteoglycan (HSPG) and surface charge on the cell adhesion process using thickness shear mode (TSM) sensor.

    PubMed

    Ergezen, E; Hong, S; Barbee, K A; Lec, R

    2007-04-15

    The effects of Heparan Sulfate Proteoglycan (HSPG) and surface charge on the cellular interactions of the cell membrane with different substrates to determine the kinetics of cell adhesion was studied using thickness shear mode (TSM) sensor. The TSM sensor was operated at its first, third, fifth and seventh harmonics. Since the penetration depth of the shear wave decreases with increases in frequency, the multi-resonance operation of the TSM sensor was used to monitor the changes in the kinetics of the cell-substrate interaction at different distances from the sensor surface. During the sedimentation and the initial attachment of the cells on the sensor surface, the changes in the sensor resonant frequency and the magnitude response were monitored. First, HSPGs were partially digested with the enzyme Heparinase III to evaluate the effect of HSPG on the cell adhesion process. The results indicated that HSPG did not have any effect on the kinetics of the initial attachment, but it did reduce the strength of steady-state cell adhesion. Next, we investigated the effect of the electrostatic interactions of the cell membrane with the substrate on the cell adhesion. In this case, the sensor surface was coated with positively charged Poly-D-Lysine (PDL). It was observed that electrostatic interaction of the negatively charged cell membrane with the PDL surface promoted the initial cell adhesion but did not support long-term cell adhesion. The multi-resonant TSM technique was shown to be a very promising method for monitoring specific interfacial effects involving in cell adhesion process in real-time.

  9. Silver halide fiber-based evanescent-wave liquid droplet sensing with thermoelectrically cooled room temperature mid-infrared quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Chen, Jian Z.; Liu, Zhijun; Gmachl, Claire F.; Sivco, Deborah L.

    2005-11-01

    Quantum cascade lasers coupled directly to unclad silver halide fibers were used to assemble mid-infrared fiber-optics evanescent-wave sensors suitable to measure the chemical composition of simple liquid droplets. Quantum cascade lasers can be designed to emit across a wide range of mid-infrared wavelengths by tailoring the quantum-well structure, and the wavelength can be fine tuned by a thermoelectric cooler. Here, laser wavelengths were chosen which offer the largest absorption contrast between two constituents of a droplet. The laser was coupled to an unclad silver halide fiber, which penetrates through the droplet resting on a hydrophobic surface. For the same liquid composition and droplet size, the transmitted intensity is weaker for a droplet on a 1H,1H,2H,2H-perfluoro-octyltrichlorosilane coated glass slide than for one on a hexadecanethiol (HDT) coated Au-covered glass slide because of the high reflectivity of the HDT/Au surface at mid-infrared wavelengths. The absorption coefficients of water, glycerol, α-tocophenol acetate, and squalane were measured by varying the immersion length of the fiber; i.e. the droplet size. A pseudo-Beer-Lambert law fits well with the experimental data. We tested both aqueous liquid mixtures (acetone/water and ethanol/water) and oil-base solutions (n-dodecane/squalane and α-tocophenol acetate/squalane); α-tocophenol acetate and squalane are common ingredients of cosmetics, either as active ingredients or for chemical stabilization. Using a 300μm diameter silver halide fiber with a 25mm immersion length, the detection limits are 1 vol.% for α-tocophenol in squalane and 2 vol.% for acetone in water for laser wavenumbers of 1208 cm -1 and 1363 cm -1, respectively. This work was previously been reported in J. Z. Chen et al. Optics Express 13, 5953 (2005).

  10. Fast and slow ion diffusion processes in lithium ion pouch cells during cycling observed with fiber optic strain sensors

    NASA Astrophysics Data System (ADS)

    Sommer, Lars Wilko; Kiesel, Peter; Ganguli, Anurag; Lochbaum, Alexander; Saha, Bhaskar; Schwartz, Julian; Bae, Chang-Jun; Alamgir, Mohamed; Raghavan, Ajay

    2015-11-01

    Cell monitoring for safe capacity utilization while maximizing pack life and performance is a key requirement for effective battery management and encouraging their adoption for clean-energy technologies. A key cell failure mode is the build-up of residual electrode strain over time, which affects both cell performance and life. Our team has been exploring the use of fiber optic (FO) sensors as a new alternative for cell state monitoring. In this present study, various charge-cycling experiments were performed on Lithium-ion pouch cells with a particular class of FO sensors, fiber Bragg gratings (FBGs), that were externally attached to the cells. An overshooting of the volume change at high SOC that recovers during rest can be observed. This phenomenon originates from the interplay between a fast and a slow Li ion diffusion process, which leads to non-homogeneous intercalation of Li ions. This paper focuses on the strain relaxation processes that occur after switching from charge to no-load phases. The correlation of the excess volume and subsequent relaxation to SOC as well as temperature is discussed. The implications of being able to monitor this phenomenon to control battery utilization for long life are also discussed.

  11. A Negative Index Metamaterial-Inspired UWB Antenna with an Integration of Complementary SRR and CLS Unit Cells for Microwave Imaging Sensor Applications

    PubMed Central

    Islam, Mohammad Tariqul; Islam, Md. Moinul; Samsuzzaman, Md.; Faruque, Mohammad Rashed Iqbal; Misran, Norbahiah

    2015-01-01

    This paper presents a negative index metamaterial incorporated UWB antenna with an integration of complementary SRR (split-ring resonator) and CLS (capacitive loaded strip) unit cells for microwave imaging sensor applications. This metamaterial UWB antenna sensor consists of four unit cells along one axis, where each unit cell incorporates a complementary SRR and CLS pair. This integration enables a design layout that allows both a negative value of permittivity and a negative value of permeability simultaneous, resulting in a durable negative index to enhance the antenna sensor performance for microwave imaging sensor applications. The proposed MTM antenna sensor was designed and fabricated on an FR4 substrate having a thickness of 1.6 mm and a dielectric constant of 4.6. The electrical dimensions of this antenna sensor are 0.20 λ × 0.29 λ at a lower frequency of 3.1 GHz. This antenna sensor achieves a 131.5% bandwidth (VSWR < 2) covering the frequency bands from 3.1 GHz to more than 15 GHz with a maximum gain of 6.57 dBi. High fidelity factor and gain, smooth surface-current distribution and nearly omni-directional radiation patterns with low cross-polarization confirm that the proposed negative index UWB antenna is a promising entrant in the field of microwave imaging sensors. PMID:26007721

  12. A Negative Index Metamaterial-Inspired UWB Antenna with an Integration of Complementary SRR and CLS Unit Cells for Microwave Imaging Sensor Applications.

    PubMed

    Islam, Mohammad Tariqul; Islam, Md Moinul; Samsuzzaman, Md; Faruque, Mohammad Rashed Iqbal; Misran, Norbahiah

    2015-05-20

    This paper presents a negative index metamaterial incorporated UWB antenna with an integration of complementary SRR (split-ring resonator) and CLS (capacitive loaded strip) unit cells for microwave imaging sensor applications. This metamaterial UWB antenna sensor consists of four unit cells along one axis, where each unit cell incorporates a complementary SRR and CLS pair. This integration enables a design layout that allows both a negative value of permittivity and a negative value of permeability simultaneous, resulting in a durable negative index to enhance the antenna sensor performance for microwave imaging sensor applications. The proposed MTM antenna sensor was designed and fabricated on an FR4 substrate having a thickness of 1.6 mm and a dielectric constant of 4.6. The electrical dimensions of this antenna sensor are 0.20 λ × 0.29 λ at a lower frequency of 3.1 GHz. This antenna sensor achieves a 131.5% bandwidth (VSWR < 2) covering the frequency bands from 3.1 GHz to more than 15 GHz with a maximum gain of 6.57 dBi. High fidelity factor and gain, smooth surface-current distribution and nearly omni-directional radiation patterns with low cross-polarization confirm that the proposed negative index UWB antenna is a promising entrant in the field of microwave imaging sensors.

  13. Quantum dots as a sensor for quantitative visualization of surface charges on single living cells with nano-scale resolution.

    PubMed

    Huang, Yao-Xiong; Zheng, Xin-Jing; Kang, Li-Li; Chen, Xing-Yao; Liu, Wen-Jing; Huang, Bao-Tian; Wu, Zheng-Jie

    2011-01-15

    We developed a technique using quantum dot (QD) as a sensor for quantitative visualization of the surface charge on biological cells with nano-scale resolution. The QD system was designed and synthesized using amino modified CdSe/ZnS nanoparticles. In a specially designed buffer solution, they are positively charged and can homogeneously disperse in the aqueous environment to label all the negative charges on the surfaces of living cells. Using a wide-field optical sectioning microscopy to achieve 2D/3D imaging of the QD-labeled cells, we determined the charge densities of different kinds of cells from normal to mutant ones. The information about the surface charge distribution is significant in evaluating the structure, function, biological behavior and even malignant transformation of cells.

  14. L-Lactate-selective microbial sensor based on flavocytochrome b2-enriched yeast cells using recombinant and nanotechnology approaches.

    PubMed

    Karkovska, Maria; Smutok, Oleh; Stasyuk, Nataliya; Gonchar, Mykhailo

    2015-11-01

    In the recent years, nanotechnology is the most developing branch due to a wide variety of potential applications in biomedical, biotechnological and agriculture fields. The binding nanoparticles with various biological molecules makes them attractive candidates for using in sensor technologies. The particularly actual is obtaining the bionanomembranes based on biocatalytic elements with improved sensing characteristics. The aim of this investigation is to study the properties of microbial L-lactate-selective sensor based on using the recombinant Hansenula polymorpha yeast cells overproducing flavocytochrome b2 (FC b2), as well as additionally enriched by the enzyme bound with gold nanoparticles (FC b2-nAu). Although, the high permeability of the living cells to nanoparticles is being intensively studied (mostly for delivery of drugs), the idea of using both recombinant technology and nanotechnology to increase the amount of the target enzyme in the biosensing layer is really novel. The FC b2-nAu-enriched living and permeabilized yeast cells were used for construction of a bioselective membrane of microbial L-lactate-selective amperometric biosensor. Phenazine methosulphate was served as a free defusing electron transfer mediator which provides effective electron transfer from the reduced enzyme to the electrode surface. It was shown that the output to L-lactate of FC b2-nAu-enriched permeabilized yeast cells is 2.5-fold higher when compared to the control cells. The obtained results confirm that additional enrichment of the recombinant yeast cell by the enzyme bound with nanoparticles improves the analytical parameters of microbial sensor.

  15. Measurement and control of dissolved carbon dioxide in mammalian cell culture processes using an in situ fiber optic chemical sensor.

    PubMed

    Pattison, R N; Swamy, J; Mendenhall, B; Hwang, C; Frohlich, B T

    2000-01-01

    At high viable cell concentrations in large-scale mammalian cell culture processes, the accumulation of dissolved carbon dioxide (dCO(2), typically quantified as an equilibrium gas-phase concentration) becomes problematic as a result of low CO(2) removal rates at reduced surface-to-volume ratios. High dCO(2) concentrations have previously been shown to inhibit cell growth and product formation in mammalian cells and to alter the glycosylation pattern of recombinant proteins. Therefore, reliable monitoring and control of dCO(2) are important for successful large-scale operation. Off-line measurements by instruments such as blood gas analyzers (BGA) are constrained by the low frequency of data collection and cannot be used for on-line control. In a preliminary evaluation of the YSI 8500 in situ sensor, a response time (t(90%)) of 6 min, sensitivity of 0.5% CO(2) (3.6 mmHg), and linearity of measurement (R(2) = 0.9997) between the equivalent gas-phase partial pressure of 0-180 mmHg (0% and 25% CO(2)) were established. Measurements were found to be unaffected by culture pH and typical mammalian cell culture concentrations of glucose, glutamine, glutamate, lactate, and ammonium. The sensor withstood repeated sterilization and cleaning cycles. The reliability of this sensor was demonstrated in microcarrier-based Chinese hamster ovary (CHO) cell perfusion cultures at reactor scales of 30, 40, 340, and 2000 L and was successfully implemented in a dCO(2) control strategy using N(2) sparging.

  16. Evanescent-wave and ambient chiral sensing by signal-reversing cavity ringdown polarimetry

    NASA Astrophysics Data System (ADS)

    Sofikitis, Dimitris; Bougas, Lykourgos; Katsoprinakis, Georgios E.; Spiliotis, Alexandros K.; Loppinet, Benoit; Rakitzis, T. Peter

    2014-10-01

    Detecting and quantifying chirality is important in fields ranging from analytical and biological chemistry to pharmacology and fundamental physics: it can aid drug design and synthesis, contribute to protein structure determination, and help detect parity violation of the weak force. Recent developments employ microwaves, femtosecond pulses, superchiral light or photoionization to determine chirality, yet the most widely used methods remain the traditional methods of measuring circular dichroism and optical rotation. However, these signals are typically very weak against larger time-dependent backgrounds. Cavity-enhanced optical methods can be used to amplify weak signals by passing them repeatedly through an optical cavity, and two-mirror cavities achieving up to 105 cavity passes have enabled absorption and birefringence measurements with record sensitivities. But chiral signals cancel when passing back and forth through a cavity, while the ubiquitous spurious linear birefringence background is enhanced. Even when intracavity optics overcome these problems, absolute chirality measurements remain difficult and sometimes impossible. Here we use a pulsed-laser bowtie cavity ringdown polarimeter with counter-propagating beams to enhance chiral signals by a factor equal to the number of cavity passes (typically >103) to suppress the effects of linear birefringence by means of a large induced intracavity Faraday rotation; and to effect rapid signal reversals by reversing the Faraday rotation and subtracting signals from the counter-propagating beams. These features allow absolute chiral signal measurements in environments where background subtraction is not feasible: we determine optical rotation from α-pinene vapour in open air, and from maltodextrin and fructose solutions in the evanescent wave produced by total internal reflection at a prism surface. The limits of the present polarimeter, when using a continuous-wave laser locked to a stable, high-finesse cavity

  17. The Sinorhizobium meliloti sensor histidine kinase CbrA contributes to free-living cell cycle regulation.

    PubMed

    Sadowski, Craig S; Wilson, Daniel; Schallies, Karla B; Walker, Graham; Gibson, Katherine E

    2013-08-01

    Sinorhizobium meliloti is alternately capable of colonizing the soil as a free-living bacterium or establishing a chronic intracellular infection with its legume host for the purpose of nitrogen fixation. We previously identified the S. meliloti two-component sensor histidine kinase CbrA as playing an important role in regulating exopolysaccharide production, flagellar motility and symbiosis. Phylogenetic analysis of CbrA has highlighted its evolutionary relatedness to the Caulobacter crescentus sensor histidine kinases PleC and DivJ, which are involved in CtrA-dependent cell cycle regulation through the shared response regulator DivK. We therefore became interested in testing whether CbrA plays a role in regulating S. meliloti cell cycle processes. We find the loss of cbrA results in filamentous cell growth accompanied by cells that contain an aberrant genome complement, indicating CbrA plays a role in regulating cell division and possibly DNA segregation. S. meliloti DivK localizes to the old cell pole during distinct phases of the cell cycle in a phosphorylation-dependent manner. Loss of cbrA results in a significantly decreased rate of DivK polar localization when compared with the wild-type, suggesting CbrA helps regulate cell cycle processes by modulating DivK phosphorylation status as a kinase. Consistent with a presumptive decrease in DivK phosphorylation and activity, we also find the steady-state level of CtrA increased in cbrA mutants. Our data therefore demonstrate that CbrA contributes to free-living cell cycle regulation, which in light of its requirement for symbiosis, points to the potential importance of cell cycle regulation for establishing an effective host interaction.

  18. Outward electron transfer by Saccharomyces cerevisiae monitored with a bi-cathodic microbial fuel cell-type activity sensor.

    PubMed

    Ducommun, Raphaël; Favre, Marie-France; Carrard, Delphine; Fischer, Fabian

    2010-03-01

    A Janus head-like bi-cathodic microbial fuel cell was constructed to monitor the electron transfer from Saccharomyces cerevisiae to a woven carbon anode. The experiments were conducted during an ethanol cultivation of 170 g/l glucose in the presence and absence of yeast-peptone medium. First, using a basic fuel-cell type activity sensor, it was shown that yeast-peptone medium contains electroactive compounds. For this purpose, 1% solutions of soy peptone and yeast extract were subjected to oxidative conditions, using a microbial fuel cell set-up corresponding to a typical galvanic cell, consisting of culture medium in the anodic half-cell and 0.5 M K(3)Fe(CN)(6) in the cathodic half-cell. Second, using a bi-cathodic microbial fuel cell, it was shown that electrons were transferred from yeast cells to the carbon anode. The participation of electroactive compounds in the electron transport was separated as background current. This result was verified by applying medium-free conditions, where only glucose was fed, confirming that electrons are transferred from yeast cells to the woven carbon anode. Knowledge about the electron transfer through the cell membrane is of importance in amperometric online monitoring of yeast fermentations and for electricity production with microbial fuel cells.

  19. Final report on the application of chaos theory to an alumina sensor for aluminum reduction cells. Inert Electrodes Program

    SciTech Connect

    Williford, R.E.; Windisch, C.F. Jr.

    1992-03-01

    Four chaos-related digital signal analysis (DSA) methods were applied to the analysis of voltage and current signals collected from aluminum electrolysis cells. Two separate data bases were analyzed: bench-scale laboratory experiments and a pilot-scale test. The objective was to assess the feasibility of using these types of data and analysis methods as the basis for a non-intrusive sensor to measure the alumina content in the electrolysis bath. This was the first time chaos theory approaches have been employed to analyze aluminum electrolysis cells.

  20. Calcium sensor kinase activates potassium uptake systems in gland cells of Venus flytraps.

    PubMed

    Scherzer, Sönke; Böhm, Jennifer; Krol, Elzbieta; Shabala, Lana; Kreuzer, Ines; Larisch, Christina; Bemm, Felix; Al-Rasheid, Khaled A S; Shabala, Sergey; Rennenberg, Heinz; Neher, Erwin; Hedrich, Rainer

    2015-06-09

    The Darwin plant Dionaea muscipula is able to grow on mineral-poor soil, because it gains essential nutrients from captured animal prey. Given that no nutrients remain in the trap when it opens after the consumption of an animal meal, we here asked the question of how Dionaea sequesters prey-derived potassium. We show that prey capture triggers expression of a K(+) uptake system in the Venus flytrap. In search of K(+) transporters endowed with adequate properties for this role, we screened a Dionaea expressed sequence tag (EST) database and identified DmKT1 and DmHAK5 as candidates. On insect and touch hormone stimulation, the number of transcripts of these transporters increased in flytraps. After cRNA injection of K(+)-transporter genes into Xenopus oocytes, however, both putative K(+) transporters remained silent. Assuming that calcium sensor kinases are regulating Arabidopsis K(+) transporter 1 (AKT1), we coexpressed the putative K(+) transporters with a large set of kinases and identified the CBL9-CIPK23 pair as the major activating complex for both transporters in Dionaea K(+) uptake. DmKT1 was found to be a K(+)-selective channel of voltage-dependent high capacity and low affinity, whereas DmHAK5 was identified as the first, to our knowledge, proton-driven, high-affinity potassium transporter with weak selectivity. When the Venus flytrap is processing its prey, the gland cell membrane potential is maintained around -120 mV, and the apoplast is acidified to pH 3. These conditions in the green stomach formed by the closed flytrap allow DmKT1 and DmHAK5 to acquire prey-derived K(+), reducing its concentration from millimolar levels down to trace levels.

  1. Calcium sensor kinase activates potassium uptake systems in gland cells of Venus flytraps

    PubMed Central

    Scherzer, Sönke; Böhm, Jennifer; Krol, Elzbieta; Shabala, Lana; Kreuzer, Ines; Larisch, Christina; Bemm, Felix; Al-Rasheid, Khaled A. S.; Shabala, Sergey; Rennenberg, Heinz; Neher, Erwin; Hedrich, Rainer

    2015-01-01

    The Darwin plant Dionaea muscipula is able to grow on mineral-poor soil, because it gains essential nutrients from captured animal prey. Given that no nutrients remain in the trap when it opens after the consumption of an animal meal, we here asked the question of how Dionaea sequesters prey-derived potassium. We show that prey capture triggers expression of a K+ uptake system in the Venus flytrap. In search of K+ transporters endowed with adequate properties for this role, we screened a Dionaea expressed sequence tag (EST) database and identified DmKT1 and DmHAK5 as candidates. On insect and touch hormone stimulation, the number of transcripts of these transporters increased in flytraps. After cRNA injection of K+-transporter genes into Xenopus oocytes, however, both putative K+ transporters remained silent. Assuming that calcium sensor kinases are regulating Arabidopsis K+ transporter 1 (AKT1), we coexpressed the putative K+ transporters with a large set of kinases and identified the CBL9-CIPK23 pair as the major activating complex for both transporters in Dionaea K+ uptake. DmKT1 was found to be a K+-selective channel of voltage-dependent high capacity and low affinity, whereas DmHAK5 was identified as the first, to our knowledge, proton-driven, high-affinity potassium transporter with weak selectivity. When the Venus flytrap is processing its prey, the gland cell membrane potential is maintained around −120 mV, and the apoplast is acidified to pH 3. These conditions in the green stomach formed by the closed flytrap allow DmKT1 and DmHAK5 to acquire prey-derived K+, reducing its concentration from millimolar levels down to trace levels. PMID:25997445

  2. Aging Studies of Sr-doped LaCrO3/YSZ/Pt Cells for an Electrochemical NOx Sensor

    SciTech Connect

    Song, S; Martin, L P; Glass, R S; Murray, E P; Visser, J H; Soltis, R E; Novak, R F; Kubinski, D J

    2005-10-05

    The stability and NO{sub x} sensing performance of electrochemical cells of the structure Sr-doped LaCrO{sub 3-{delta}} (LSC)/yttria-stabilized zirconia (YSZ)/Pt are being investigated for use in NO{sub x} aftertreatment systems in diesel vehicles. Among the requirements for NO{sub x} sensor materials in these systems are stability and long lifetime (up to ten years) in the exhaust environment. In this study, cell aging effects were explored following extended exposure to a test environment of 10% O{sub 2} at operating temperatures of 600-700 C. The data show that aging results in changes in particle morphology, chemical composition and interfacial structure, Impedance spectroscopy indicated an initial increase in the cell resistance during the early stages of aging, which is correlated to densification of the Pt electrode. Also, x-ray photoelectron spectroscopy indicated formation of SrZrO{sub 2} solid state reaction product in the LSC, a process which is of finite duration. Subsequently, the overall cell resistance decreases with aging time due, in part, to roughening of YSZ-LSC interface, which improves interface adherence and enhances charge transfer kinetics at the O{sub 2}/YSZ/LSC triple phase boundary. This study constitutes a first step in the development of a basic understanding of aging phenomena in solid state electrochemical systems with application not only to sensors, but also to fuel cells, membranes, and electrolyzers.

  3. Cell Selection Game for Densely-Deployed Sensor and Mobile Devices In 5G Networks Integrating Heterogeneous Cells and the Internet of Things.

    PubMed

    Wang, Lusheng; Wang, Yamei; Ding, Zhizhong; Wang, Xiumin

    2015-09-18

    With the rapid development of wireless networking technologies, the Internet of Things and heterogeneous cellular networks (HCNs) tend to be integrated to form a promising wireless network paradigm for 5G. Hyper-dense sensor and mobile devices will be deployed under the coverage of heterogeneous cells, so that each of them could freely select any available cell covering it and compete for resource with others selecting the same cell, forming a cell selection (CS) game between these devices. Since different types of cells usually share the same portion of the spectrum, devices selecting overlapped cells can experience severe inter-cell interference (ICI). In this article, we study the CS game among a large amount of densely-deployed sensor and mobile devices for their uplink transmissions in a two-tier HCN. ICI is embedded with the traditional congestion game (TCG), forming a congestion game with ICI (CGI) and a congestion game with capacity (CGC). For the three games above, we theoretically find the circular boundaries between the devices selecting the macrocell and those selecting the picocells, indicated by the pure strategy Nash equilibria (PSNE). Meanwhile, through a number of simulations with different picocell radii and different path loss exponents, the collapse of the PSNE impacted by severe ICI (i.e., a large number of picocell devices change their CS preferences to the macrocell) is profoundly revealed, and the collapse points are identified.

  4. Cell Selection Game for Densely-Deployed Sensor and Mobile Devices In 5G Networks Integrating Heterogeneous Cells and the Internet of Things

    PubMed Central

    Wang, Lusheng; Wang, Yamei; Ding, Zhizhong; Wang, Xiumin

    2015-01-01

    With the rapid development of wireless networking technologies, the Internet of Things and heterogeneous cellular networks (HCNs) tend to be integrated to form a promising wireless network paradigm for 5G. Hyper-dense sensor and mobile devices will be deployed under the coverage of heterogeneous cells, so that each of them could freely select any available cell covering it and compete for resource with others selecting the same cell, forming a cell selection (CS) game between these devices. Since different types of cells usually share the same portion of the spectrum, devices selecting overlapped cells can experience severe inter-cell interference (ICI). In this article, we study the CS game among a large amount of densely-deployed sensor and mobile devices for their uplink transmissions in a two-tier HCN. ICI is embedded with the traditional congestion game (TCG), forming a congestion game with ICI (CGI) and a congestion game with capacity (CGC). For the three games above, we theoretically find the circular boundaries between the devices selecting the macrocell and those selecting the picocells, indicated by the pure strategy Nash equilibria (PSNE). Meanwhile, through a number of simulations with different picocell radii and different path loss exponents, the collapse of the PSNE impacted by severe ICI (i.e., a large number of picocell devices change their CS preferences to the macrocell) is profoundly revealed, and the collapse points are identified. PMID:26393617

  5. Eliminating Unwanted Far-Field Excitation in Objective-Type TIRF. Part II. Combined Evanescent-Wave Excitation and Supercritical-Angle Fluorescence Detection Improves Optical Sectioning

    PubMed Central

    Brunstein, Maia; Hérault, Karine; Oheim, Martin

    2014-01-01

    Azimuthal beam scanning makes evanescent-wave (EW) excitation isotropic, thereby producing total internal reflection fluorescence (TIRF) images that are evenly lit. However, beam spinning does not fundamentally address the problem of propagating excitation light that is contaminating objective-type TIRF. Far-field excitation depends more on the specific objective than on cell scattering. As a consequence, the excitation impurities in objective-type TIRF are only weakly affected by changes of azimuthal or polar beam angle. These are the main results of the first part of this study (Eliminating unwanted far-field excitation in objective-type TIRF. Pt.1. Identifying sources of nonevanescent excitation light). This second part focuses on exactly where up beam in the illumination system stray light is generated that gives rise to nonevanescent components in TIRF. Using dark-field imaging of scattered excitation light we pinpoint the objective, intermediate lenses and, particularly, the beam scanner as the major sources of stray excitation. We study how adhesion-molecule coating and astrocytes or BON cells grown on the coverslip surface modify the dark-field signal. On flat and weakly scattering cells, most background comes from stray reflections produced far from the sample plane, in the beam scanner and the objective lens. On thick, optically dense cells roughly half of the scatter is generated by the sample itself. We finally show that combining objective-type EW excitation with supercritical-angle fluorescence (SAF) detection efficiently rejects the fluorescence originating from deeper sample regions. We demonstrate that SAF improves the surface selectivity of TIRF, even at shallow penetration depths. The coplanar microscopy scheme presented here merges the benefits of beam spinning EW excitation and SAF detection and provides the conditions for quantitative wide-field imaging of fluorophore dynamics at or near the plasma membrane. PMID:24606929

  6. Carbon nanoparticle-based ratiometric fluorescent sensor for detecting mercury ions in aqueous media and living cells.

    PubMed

    Lan, Minhuan; Zhang, Jinfeng; Chui, Ying-San; Wang, Pengfei; Chen, Xianfeng; Lee, Chun-Sing; Kwong, Hoi-Lun; Zhang, Wenjun

    2014-12-10

    A novel nanohybrid ratiometric fluorescence sensor is developed for selective detection of mercuric ions (Hg(2+)), and the application has been successfully demonstrated in HEPES buffer solution, lake water, and living cells. The sensor comprises water-soluble fluorescent carbon nanoparticles (CNPs) and Rhodamine B (RhB) and exhibits their corresponding dual emissions peaked at 437 and 575 nm, respectively, under a single excitation wavelength (350 nm). The photoluminescence of the CNPs in the nanohybrid system can be completely quenched by Hg(2+) through effective electron or energy transfer process due to synergetic strong electrostatic interaction and metal-ligand coordination between the surface functional group of CNPs and Hg(2+), while that of the RhB remains constant. This results in an obviously distinguishable fluorescence color variation (from violet to orange) of the nanohybrid solution. This novel sensor can effectively identify Hg(2+) from other metal ions with relatively low background interference even in a complex system such as lake water. The detection limit of this method is as low as 42 nM. Furthermore, the sensing technique is applicable to detect Hg(2+) in living cells.

  7. ZBP1/DAI is an innate sensor of influenza virus triggering the NLRP3 inflammasome and programmed cell death pathways

    PubMed Central

    Kuriakose, Teneema; Man, Si Ming; Malireddi, R.K. Subbarao; Karki, Rajendra; Kesavardhana, Sannula; Place, David E.; Neale, Geoffrey; Vogel, Peter; Kanneganti, Thirumala-Devi

    2016-01-01

    The interferon-inducible protein Z-DNA binding protein 1 (ZBP1, also known as DNA-dependent activator of IFN-regulatory factors (DAI) and DLM-1) was identified as a dsDNA sensor, which instigates innate immune responses. However, this classification has been disputed and whether ZBP1 functions as a pathogen sensor during an infection has remained unknown. Herein, we demonstrated ZBP1-mediated sensing of the influenza A virus (IAV) proteins NP and PB1, triggering cell death and inflammatory responses via the RIPK1–RIPK3–Caspase-8 axis. ZBP1 regulates NLRP3 inflammasome activation as well as induction of apoptosis, necroptosis and pyroptosis in IAV-infected cells. Importantly, ZBP1 deficiency protected mice from mortality during IAV infection owing to reduced inflammatory responses and epithelial damage. Overall, these findings indicate that ZBP1 is an innate immune sensor of IAV and highlight its importance in the pathogenesis of IAV infection. PMID:27917412

  8. Reporter genes lucFF, luxCDABE, gfp, and dsred have different characteristics in whole-cell bacterial sensors.

    PubMed

    Hakkila, Kaisa; Maksimow, Mikael; Karp, Matti; Virta, Marko

    2002-02-15

    The selection of a genetic reporter can be difficult because of the wide range of genes available. In order to reduce the selection, we compared the performance of different reporter genes: firefly luciferase (Photinus pyralis lucFF), bacterial luciferase operon (Photorhabdus luminescens luxCDABE), green fluorescent protein (Aequorea victoria gfp), and red fluorescent protein (Discosoma sp. dsred) in whole-cell bacterial sensors. Escherichia coli sensor bacteria were engineered to contain a reporter plasmid that carries the reporter gene under the control of mercury- (mer from Tn21) or arsenite- (ars from R773) responsive regulatory units. Characteristics of the strains were studied by using different arsenite or mercury concentrations and incubation times. The lowest detectable concentration of analytes and the fastest responses were achieved with lucFF or luxCDABE as reporter genes. The fluorescent proteins, GFP and DsRed, gave responses at higher analyte concentrations and after significantly longer incubation times. The results indicate that luciferases are better reporters in whole-cell sensor bacteria.

  9. Cell-like pressure sensors reveal increase of mechanical stress towards the core of multicellular spheroids under compression

    PubMed Central

    Dolega, M. E.; Delarue, M.; Ingremeau, F.; Prost, J.; Delon, A.; Cappello, G.

    2017-01-01

    The surrounding microenvironment limits tumour expansion, imposing a compressive stress on the tumour, but little is known how pressure propagates inside the tumour. Here we present non-destructive cell-like microsensors to locally quantify mechanical stress distribution in three-dimensional tissue. Our sensors are polyacrylamide microbeads of well-defined elasticity, size and surface coating to enable internalization within the cellular environment. By isotropically compressing multicellular spheroids (MCS), which are spherical aggregates of cells mimicking a tumour, we show that the pressure is transmitted in a non-trivial manner inside the MCS, with a pressure rise towards the core. This observed pressure profile is explained by the anisotropic arrangement of cells and our results suggest that such anisotropy alone is sufficient to explain the pressure rise inside MCS composed of a single cell type. Furthermore, such pressure distribution suggests a direct link between increased mechanical stress and previously observed lack of proliferation within the spheroids core. PMID:28128198

  10. 456-mW graphene Q-switched Yb:yttria waveguide laser by evanescent-field interaction.

    PubMed

    Choudhary, Amol; Beecher, Stephen J; Dhingra, Shonali; D'Urso, Brian; Parsonage, Tina L; Grant-Jacob, James A; Hua, Ping; Mackenzie, Jacob I; Eason, Robert W; Shepherd, David P

    2015-05-01

    In this Letter, we present a passively Q-switched Yb:Y2O3 waveguide laser using evanescent-field interaction with an atmospheric-pressure-chemical-vapor-deposited graphene saturable absorber. The waveguide, pumped by a broad area diode laser, produced an average output power of 456 mW at an absorbed power of 4.1 W. The corresponding pulse energy and peak power were 330 nJ and 2 W, respectively. No graphene damage was observed, demonstrating the suitability of top-deposited graphene for high-power operation.

  11. Suppression of sound radiation to far field of near-field acoustic communication system using evanescent sound field

    NASA Astrophysics Data System (ADS)

    Fujii, Ayaka; Wakatsuki, Naoto; Mizutani, Koichi

    2016-01-01

    A method of suppressing sound radiation to the far field of a near-field acoustic communication system using an evanescent sound field is proposed. The amplitude of the evanescent sound field generated from an infinite vibrating plate attenuates exponentially with increasing a distance from the surface of the vibrating plate. However, a discontinuity of the sound field exists at the edge of the finite vibrating plate in practice, which broadens the wavenumber spectrum. A sound wave radiates over the evanescent sound field because of broadening of the wavenumber spectrum. Therefore, we calculated the optimum distribution of the particle velocity on the vibrating plate to reduce the broadening of the wavenumber spectrum. We focused on a window function that is utilized in the field of signal analysis for reducing the broadening of the frequency spectrum. The optimization calculation is necessary for the design of window function suitable for suppressing sound radiation and securing a spatial area for data communication. In addition, a wide frequency bandwidth is required to increase the data transmission speed. Therefore, we investigated a suitable method for calculating the sound pressure level at the far field to confirm the variation of the distribution of sound pressure level determined on the basis of the window shape and frequency. The distribution of the sound pressure level at a finite distance was in good agreement with that obtained at an infinite far field under the condition generating the evanescent sound field. Consequently, the window function was optimized by the method used to calculate the distribution of the sound pressure level at an infinite far field using the wavenumber spectrum on the vibrating plate. According to the result of comparing the distributions of the sound pressure level in the cases with and without the window function, it was confirmed that the area whose sound pressure level was reduced from the maximum level to -50 dB was

  12. Evanescent field interaction of tapered fiber with graphene oxide in generation of wide-bandwidth mode-locked pulses

    NASA Astrophysics Data System (ADS)

    Ahmad, H.; Faruki, M. J.; Razak, M. Z. A.; Tiu, Z. C.; Ismail, M. F.

    2017-02-01

    Pulses with picosecond pulse widths are highly desired for high precision laser applications. A mode-locked pulse laser utilizing evanescent field interaction of a tapered fiber with graphene oxide (GO) is demonstrated. A homemade fabrication stage was used to fabricate the tapered fiber using systematic flame brushing and a GO solution was used to coat the microfiber using optical deposition technique. Pulse trains with a pulse width of 3.46 ps, a 3 dB optical bandwidth of 11.82 nm and a repetition rate of 920 kHz were obtained. The system has substantial potential for many crucial medical, communication, bio processing, military, and industrial applications.

  13. BLOCH modes dressed by evanescent waves and the generalized Goos-Hänchen effect in photonic crystals.

    PubMed

    Felbacq, Didier; Smaâli, Rafik

    2004-05-14

    It is common knowledge that in an infinite periodic medium, for instance, an infinite photonic crystal, the direction of propagation of a monochromatic wave packet is given by the normal to the isofrequency diagram. We show that this is no longer true in a finite size medium, due to the existence of evanescent waves near the interfaces of the photonic crystal. We derive a renormalized isofrequency diagram giving the correct direction. We give a physical interpretation, showing that this phenomenon can be considered as a generalized Goos-Hänchen effect.

  14. Ammonia and ammonium hydroxide sensors for ammonia/water absorption machines: Literature review and data compilation

    NASA Astrophysics Data System (ADS)

    Anheier, N. C., Jr.; McDonald, C. E.; Cuta, J. M.; Cuta, F. M.; Olsen, K. B.

    1995-05-01

    This report describes an evaluation of various sensing techniques for determining the ammonia concentration in the working fluid of ammonia/water absorption cycle systems. The purpose was to determine if any existing sensor technology or instrumentation could provide an accurate, reliable, and cost-effective continuous measure of ammonia concentration in water. The resulting information will be used for design optimization and cycle control in an ammonia-absorption heat pump. Pacific Northwest Laboratory (PNL) researchers evaluated each sensing technology against a set of general requirements characterizing the potential operating conditions within the absorption cycle. The criteria included the physical constraints for in situ operation, sensor characteristics, and sensor application. PNL performed an extensive literature search, which uncovered several promising sensing technologies that might be applicable to this problem. Sixty-two references were investigated, and 33 commercial vendors were identified as having ammonia sensors. The technologies for ammonia sensing are acoustic wave, refractive index, electrode, thermal, ion-selective field-effect transistor (ISFET), electrical conductivity, pH/colormetric, and optical absorption. Based on information acquired in the literature search, PNL recommends that follow-on activities focus on ISFET devices and a fiber optic evanescent sensor with a colormetric indicator. The ISFET and fiber optic evanescent sensor are inherently microminiature and capable of in situ measurements. Further, both techniques have been demonstrated selective to the ammonium ion (NH4(+)). The primary issue remaining is how to make the sensors sufficiently corrosion-resistant to be useful in practice.

  15. Ammonia and ammonium hydroxide sensors for ammonia/water absorption machines: Literature review and data compilation

    SciTech Connect

    Anheier, N.C. Jr.; McDonald, C.E.; Cuta, J.M.; Cuta, F.M.; Olsen, K.B.

    1995-05-01

    This report describes an evaluation of various sensing techniques for determining the ammonia concentration in the working fluid of ammonia/water absorption cycle systems. The purpose of this work was to determine if any existing sensor technology or instrumentation could provide an accurate, reliable, and cost-effective continuous measure of ammonia concentration in water. The resulting information will be used for design optimization and cycle control in an ammonia-absorption heat pump. PNL researchers evaluated each sensing technology against a set of general requirements characterizing the potential operating conditions within the absorption cycle. The criteria included the physical constraints for in situ operation, sensor characteristics, and sensor application. PNL performed an extensive literature search, which uncovered several promising sensing technologies that might be applicable to this problem. Sixty-two references were investigated, and 33 commercial vendors were identified as having ammonia sensors. The technologies for ammonia sensing are acoustic wave, refractive index, electrode, thermal, ion-selective field-effect transistor (ISFET), electrical conductivity, pH/colormetric, and optical absorption. Based on information acquired in the literature search, PNL recommends that follow-on activities focus on ISFET devices and a fiber optic evanescent sensor with a colormetric indicator. The ISFET and fiber optic evanescent sensor are inherently microminiature and capable of in situ measurements. Further, both techniques have been demonstrated selective to the ammonium ion (NH{sub 4}{sup +}). The primary issue remaining is how to make the sensors sufficiently corrosion-resistant to be useful in practice.

  16. Sensitivity and directionality of lipid bilayer mechanotransduction studied using a revised, highly durable membrane-based hair cell sensor

    NASA Astrophysics Data System (ADS)

    Tamaddoni, Nima; Freeman, Eric C.; Sarles, Stephen A.

    2015-06-01

    A bioinspired, membrane-based hair cell sensor consists of a planar lipid bilayer formed between two lipid-coated water droplets that connect to an artificial hair. This assembly enables motion of the hair caused by mechanical stimuli to vibrate the bilayer and produce a capacitive current. In this work, the mechanoelectrical transduction mechanism and sensing performance is experimentally characterized for a more-durable, revised hair cell embodiment that includes a cantilevered hair rooted firmly in the surrounding solid substrate. Specifically, this study demonstrates that the revised membrane-based hair cell sensor produces higher time rates of change in capacitance (0.8-6.0 nF s-1) in response to airflow across the hair compared to the original sensor (45-60 pF s-1) that did not feature a cantilevered hair. The 10-fold to 100-fold increase in the time rate change of capacitance corresponds to greater membrane bending and, thus, higher sensing currents. Membranes in the revised sensor exhibit changes in area due to bending on the order of 0.2-2.0%, versus 0.02% for the original sensor. Experiments also reveal that the bilayer displays highest sensitivity to mechanical perturbations normal to the plane of the bilayer, a membrane can transduce hair motion at frequencies below the hair’s characteristic frequency, and bilayers formed between polymerized hydrogel volumes exhibit a higher sensing currents than those formed between liquid aqueous volumes. Finally, measurements of sensitivity (5-35 pA m-1 s-1) and minimum (4.0-0.6 m s-1) and maximum (28-13 m s-1) sensing thresholds to airflow are performed for the first time, and we observe maximum electrical power (˜65 pW) in the membrane occurs for combinations of slower airflow and higher voltage. These results highlight that along with the dimensions of the hair and the compositions of the aqueous volumes, sensing performance can be tuned with applied voltage.

  17. Evaluation of therapeutic effects of natural killer (NK) cell-based immunotherapy in mice using in vivo apoptosis bioimaging with a caspase-3 sensor.

    PubMed

    Lee, Ho Won; Singh, Thoudam Debraj; Lee, Sang-Woo; Ha, Jeoung-Hee; Rehemtulla, Alnawaz; Ahn, Byeong-Cheol; Jeon, Young Hyun; Lee, Jaetae

    2014-07-01

    Natural killer (NK) cell-based immunotherapy is a promising strategy for cancer treatment, and caspase-3 is an important effector molecule in NK cell-mediated apoptosis in cancers. Here, we evaluated the antitumor effects of NK cell-based immunotherapy by serial noninvasive imaging of apoptosis using a caspase-3 sensor in mice with human glioma xenografts. Human glioma cells expressing both a caspase-3 sensor as a surrogate marker for caspase-3 activation and Renilla luciferase (Rluc) as a surrogate marker for cell viability were established and referred to as D54-CR cells. Human NK92 cells were used as effector cells. Treatment with NK92 cells resulted in a time- and effector number-dependent increase in bioluminescence imaging (BLI) activity of the caspase-3 sensor in D54-CR cells in vitro. Caspase-3 activation by NK92 treatment was blocked by Z-VAD treatment in D54-CR cells. Transfusion of NK92 cells induced an increase of the BLI signal by caspase-3 activation in a dose- and time-dependent manner in D54-CR tumor-bearing mice but not in PBS-treated mice. Accordingly, sequential BLI with the Rluc reporter gene revealed marked retardation of tumor growth in the NK92-treatment group but not in the PBS-treatment group. These data suggest that noninvasive imaging of apoptosis with a caspase-3 sensor can be used as an effective tool for evaluation of therapeutic efficacy as well as for optimization of NK cell-based immunotherapy.-Lee, H. W., Singh, T. D., Lee, S.-W., Ha, J.-H., Rehemtulla, A., Ahn, B.-C., Jeon, Y.-H., Lee, J. Evaluation of therapeutic effects of natural killer (NK) cell-based immunotherapy in mice using in vivo apoptosis bioimaging with a caspase-3 sensor.

  18. Fabrication of a cyclic olefin copolymer planar waveguide embedded in a multi-channel poly(methyl methacrylate) fluidic chip for evanescence excitation.

    PubMed

    Okagbare, Paul I; Emory, Jason M; Datta, Proyag; Goettert, Jost; Soper, Steven A

    2010-01-07

    The fabrication and characterization of a novel cyclic olefin copolymer (COC) waveguide embedded in a poly(methyl methacrylate), PMMA, fluidic chip configured in a multi-channel format with an integrated monolithic prism for evanescent fluorescence excitation are reported. The fabrication approach allowed the embedded waveguide to be situated orthogonal to a series of fluidic channels within the PMMA wafer to sample fluorescent solutions in these channels using the evanescence properties of the waveguide. Construction of the device was achieved using several fabrication techniques including high precision micromilling, hot embossing and stenciling of a polymer melt to form the waveguide and coupling prism. A waveguide channel was fabricated in the fluidic chip's cover plate, also made from PMMA, and was loaded with a COC solution using a pre-cast poly(dimethylsiloxane), PDMS, stencil containing a prism-shaped recess. The PMMA substrate contained multiple channels (100 microm wide x 30 microm deep with a pitch of 100 microm) that were situated orthogonal to the waveguide to allow penetration of the evanescent field into the sampling solution. The optical properties of the waveguide in terms of its transmission properties and penetration depth of the evanescent field in the adjacent solution were evaluated. Finally, the device was used for laser-induced fluorescence evanescent excitation of a dye solution hydrodynamically flowing through multiple microfluidic channels in the chip and processed using a microscope equipped with a charge-coupled device (CCD) for parallel readout. The device and optical system were able to image 11 channels simultaneously with a limit-of-detection of 7.1 x 10(-20) mol at a signal-to-noise ratio of 2. The waveguide was simple to manufacture and could be scaled to illuminate much higher channel numbers making it appropriate for high-throughput measurements using evanescent excitation.

  19. Sound source identification in a noisy environment based on inverse patch transfer functions with evanescent Green's functions

    NASA Astrophysics Data System (ADS)

    Xiang, Shang; Jiang, Weikang; Pan, Siwei

    2015-12-01

    A modified inverse patch transfer function (iPTF) method is used to reconstruct the normal velocities of the target source in a noisy environment. The iPTF method simplifies the Helmholtz integral equation to one term by constructing a Green's function satisfying Neumann boundary conditions for an enclosure, which is generally constructed by slowly convergent modal expansions. The main objective of the present work is to provide an evanescent Green's function to improve the convergence of calculations. A brief description of the iPTF method and two sets of Green's functions for a rectangular cavity are presented firstly. In simulations, both the Green's functions are used to calculate the condition numbers of impedance matrices describing the relation between source and measurement patches, and the time cost of calculation based on the two sets of Green's functions at 450 Hz is compared. Double pressure measurements are then employed as the input data instead of pressure and velocity measurements. The normal velocities of two baffled loudspeakers are reconstructed by the combination of a measurement method and a Green's function in the presence of a disturbing source in the frequency range of 50-1000 Hz. In addition, the double pressure measurements are examined by an experiment. The precise identification of the sources indicates that the double pressure measurements are capable of localizing sources in a noisy environment. It is also found that the reconstruction with the evanescent Green's functions is slightly better than that with the modal expansions.

  20. Development and Long-Term Stability of a Novel Microbial Fuel Cell BOD Sensor with MnO₂ Catalyst.

    PubMed

    Kharkwal, Shailesh; Tan, Yi Chao; Lu, Min; Ng, How Yong

    2017-01-28

    A novel microbial fuel cell (MFC)-based biosensor was designed for continuous monitoring of biochemical oxygen demand (BOD) in real wastewater. To lower the material cost, manganese dioxide (MnO₂) was tested as an innovative cathode catalyst for oxygen reduction in a single chamber air-cathode MFC, and two different crystalline structures obtained during synthesis of MnO₂ (namely β- and γ-MnO₂) were compared. The BOD sensor was studied in a comprehensive way, using both sodium acetate solution and real domestic wastewater (DWW). The optimal performance of the sensor was obtained with a β-MnO₂ catalyst, with R² values of 0.99 and 0.98 using sodium acetate solution and DWW, respectively. The BOD values predicted by the β-MnO₂ biosensor for DWW were in agreement with the BOD₅ values, determined according to standard methods, with slight variations in the range from 3% to 12%. Finally, the long-term stability of the BOD biosensor was evaluated over 1.5 years. To the best of our knowledge, this is the first report of an MFC BOD sensor using an MnO₂ catalyst at the cathode; the feasibility of using a low-cost catalyst in an MFC for online measurement of BOD in real wastewater broadens the scope of applications for such devices.

  1. Development and Long-Term Stability of a Novel Microbial Fuel Cell BOD Sensor with MnO2 Catalyst

    PubMed Central

    Kharkwal, Shailesh; Tan, Yi Chao; Lu, Min; Ng, How Yong

    2017-01-01

    A novel microbial fuel cell (MFC)-based biosensor was designed for continuous monitoring of biochemical oxygen demand (BOD) in real wastewater. To lower the material cost, manganese dioxide (MnO2) was tested as an innovative cathode catalyst for oxygen reduction in a single chamber air-cathode MFC, and two different crystalline structures obtained during synthesis of MnO2 (namely β- and γ-MnO2) were compared. The BOD sensor was studied in a comprehensive way, using both sodium acetate solution and real domestic wastewater (DWW). The optimal performance of the sensor was obtained with a β-MnO2 catalyst, with R2 values of 0.99 and 0.98 using sodium acetate solution and DWW, respectively. The BOD values predicted by the β-MnO2 biosensor for DWW were in agreement with the BOD5 values, determined according to standard methods, with slight variations in the range from 3% to 12%. Finally, the long-term stability of the BOD biosensor was evaluated over 1.5 years. To the best of our knowledge, this is the first report of an MFC BOD sensor using an MnO2 catalyst at the cathode; the feasibility of using a low-cost catalyst in an MFC for online measurement of BOD in real wastewater broadens the scope of applications for such devices. PMID:28134838

  2. Construction of a highly sensitive non-enzymatic sensor for superoxide anion radical detection from living cells.

    PubMed

    Liu, Yuelin; Liu, Xiuhui; Liu, Yidan; Liu, Guoan; Ding, Lan; Lu, Xiaoquan

    2017-04-15

    A novel non-enzymatic superoxide anion (O2•(-)) sensor was fabricated based on Ag nanoparticles (NPs)/L-cysteine functioned carbon nanotubes (Cys-MWCNTs) nanocomposites and used to measure the release of O2•(-) from living cells. In this strategy, AgNPs could be uniformly electrodeposited on the MWCNTs surface with average diameter of about 20nm as exhibited by scanning electronmicroscopy (SEM). Electrochemical study demonstrated that the AgNPs/Cys-MWCNTs modified glassy carbon electrode exhibited excellent catalytic activity toward the reduction of O2•(-) with a super wide linear range from 7.00×10(-11) to 7.41×10(-5)M and a low detection limit (LOD) of 2.33×10(-11)M (S/N=3). Meanwhile, the mechanism for O2•(-) reduction was also proposed for the first time. Importantly, this novel non-enzymatic O2•(-) sensor can detect O2•(-) release from cancer cells under both the external stimulation and the normal condition, which has the great potential application in clinical diagnostics to assess oxidative stress of living cells.

  3. Methanol selective fibre-optic gas sensor with a nanoporous thin film of organic-inorganic hybrid multilayers

    NASA Astrophysics Data System (ADS)

    Wang, T.; Okuda, H.; Lee, S.-W.

    2015-07-01

    The development of an evanescent wave optical fibre (EWOF) sensor modified with an organic-inorganic hybrid nanoporous thin film for alcohol vapor detection was demonstrated. The optical fibre with a core diameter of 200 μm was bent into U-shape probe optic fibre to enhance the penetation depth of light transferred into the evanescent filed. The bended region of the fibre was modified with a multilayered thin film of poly(allyamine hydrochloride) and silica nanoparticels, (PAH/SiO2)n, by a layer-by-layer (LbL) film deposition technique, followed by infusion of tetrakis(4- sulfophenyl)porphine, TPPS. The mesoporous film structure showed high sensitivity and selectivity to methanol by the aid of the TPPS infused inside the film. The optical sensor response was reversible and reproducible over many times of exposures to analytes, which was caused by the change in refractive index (RI) of the film.

  4. Distributed All-Optical Sensor to Detect dCO2 in Aqueous Environments

    NASA Astrophysics Data System (ADS)

    Bhatia, S.; Coelho, J.; Melo, L.; Davies, B.; Ahmed, F.; Bao, B.; Wild, P.; Risk, D. A.; Sinton, D.; Jun, M.

    2012-12-01

    Already a proven technology for temperature and stress measurements, an all-optical sensor to detect dCO2 is being developed for deployment in challenging environments. Optical sensors function under high pressure, do not require electronics and therefore experience no magnetic interference. They are also able to transmit signals over long distances with minimal losses. The dCO2 sensor's principal application is in measurement monitoring and verification of carbon capture and storage sites; however, it could also be useful in ocean, fresh water, and transition environments. The objective for the first phase of development was to detect a CO2 signal in laboratory tests. The developmental program incorporated experiments to detect CO2 under high pressure (1400 psi) in aqueous environments. Laboratory testing involved a custom pressure cell, off-the-shelf and custom long period gratings written in SMF125 fiber. Femptosecond laser micromachining was used to test alternative long period grating (LPG) and cutout shapes to maximize evanescent field interaction with the environment. A comprehensive program of geochemical modeling using PHREEQC 2 was used to identify the diversity of species in environments of interest that could exert confounding influence. Purchased UV-LPG responded to changes in concentration of scCO2 in brine at high pressure. Signal differences between CO2-saturated brine and pure brine were also noted under the same, high pressure conditions. Geochemical modeling software, PHREEQC 2, revealed a diversity of species in environments of interest whose concentrations varied strongly with temperature and pH. The modeling program's detailed characterization of environments informed work currently being undertaken as part of Phase 2, to develop a CO2-selective membrane to filter out measurement artifact.

  5. A novel method for in-situ monitoring of local voltage, temperature and humidity distributions in fuel cells using flexible multi-functional micro sensors.

    PubMed

    Lee, Chi-Yuan; Fan, Wei-Yuan; Chang, Chih-Ping

    2011-01-01

    In this investigation, micro voltage, temperature and humidity sensors were fabricated and integrated for the first time on a stainless steel foil using micro-electro-mechanical systems (MEMS). These flexible multi-functional micro sensors have the advantages of high temperature resistance, flexibility, smallness, high sensitivity and precision of location. They were embedded in a proton exchange membrane fuel cell (PEMFC) and used to simultaneously measure variations in the inner voltage, temperature and humidity. The accuracy and reproducibility of the calibrated results obtained using the proposed micro sensors is excellent. The experimental results indicate that, at high current density and 100%RH or 75%RH, the relative humidity midstream and downstream saturates due to severe flooding. The performance of the PEM fuel cell can be stabilized using home-made flexible multi-functional micro sensors by the in-situ monitoring of local voltage, temperature and humidity distributions within it.

  6. A Novel Method for In-Situ Monitoring of Local Voltage, Temperature and Humidity Distributions in Fuel Cells Using Flexible Multi-Functional Micro Sensors

    PubMed Central

    Lee, Chi-Yuan; Fan, Wei-Yuan; Chang, Chih-Ping

    2011-01-01

    In this investigation, micro voltage, temperature and humidity sensors were fabricated and integrated for the first time on a stainless steel foil using micro-electro-mechanical systems (MEMS). These flexible multi-functional micro sensors have the advantages of high temperature resistance, flexibility, smallness, high sensitivity and precision of location. They were embedded in a proton exchange membrane fuel cell (PEMFC) and used to simultaneously measure variations in the inner voltage, temperature and humidity. The accuracy and reproducibility of the calibrated results obtained using the proposed micro sensors is excellent. The experimental results indicate that, at high current density and 100%RH or 75%RH, the relative humidity midstream and downstream saturates due to severe flooding. The performance of the PEM fuel cell can be stabilized using home-made flexible multi-functional micro sensors by the in-situ monitoring of local voltage, temperature and humidity distributions within it. PMID:22319361

  7. Model-based cell number quantification using online single-oxygen sensor data for tissue engineering perfusion bioreactors.

    PubMed

    Lambrechts, T; Papantoniou, I; Sonnaert, M; Schrooten, J; Aerts, J-M

    2014-10-01

    Online and non-invasive quantification of critical tissue engineering (TE) construct quality attributes in TE bioreactors is indispensable for the cost-effective up-scaling and automation of cellular construct manufacturing. However, appropriate monitoring techniques for cellular constructs in bioreactors are still lacking. This study presents a generic and robust approach to determine cell number and metabolic activity of cell-based TE constructs in perfusion bioreactors based on single oxygen sensor data in dynamic perfusion conditions. A data-based mechanistic modeling technique was used that is able to correlate the number of cells within the scaffold (R(2)  = 0.80) and the metabolic activity of the cells (R(2)  = 0.82) to the dynamics of the oxygen response to step changes in the perfusion rate. This generic non-destructive measurement technique is effective for a large range of cells, from as low as 1.0 × 10(5) cells to potentially multiple millions of cells, and can open-up new possibilities for effective bioprocess monitoring.

  8. Ultrasensitive detection of superoxide anion released from living cells using a porous Pt-Pd decorated enzymatic sensor.

    PubMed

    Zhu, Xiang; Liu, Tingting; Zhao, Hongli; Shi, Libo; Li, Xiaoqing; Lan, Minbo

    2016-05-15

    Considering the critical roles of superoxide anion (O2(∙-)) in pathological conditions, it is of great urgency to establish a reliable and durable approach for real-time determination of O2(∙-). In this study, we propose a porous Pt-Pd decorated superoxide dismutase (SOD) sensor for qualitative and quantitative detection O2(∙-). The developed biosensor exhibits a fast, selective and linear amperometric response upon O2(∙-) in the concentration scope of 16 to 1,536 μM (R(2)=0.9941), with a detection limit of 0.13 μM (S/N=3) and a low Michaelis-Menten constant of 1.37 μM which indicating a high enzymatic activity and affinity to O2(∙-). Inspiringly, the proposed sensor possesses an ultrahigh sensitivity of 1270 μA mM(-1)cm(-2). In addition, SOD/porous Pt-Pd sensor exhibits excellent anti-interference property, reproducibility and long-term storage stability. Beyond our expectation, the trace level of O2(∙-) released from living cells has also been successfully captured. These satisfactory results are mainly ascribed to (1) the porous interface with larger surface area and more active sites to provide a biocompatible environment for SOD (2) the specific biocatalysis of SOD towards O2(∙-) and (3) porous Pt-Pd nanomaterials fastening the electron transfer. The superior electrochemical performance makes SOD/porous Pt-Pd sensor a promising candidate for monitoring the dynamic changes of O2(∙-)in vivo.

  9. High performance surface plasmon sensors: Simulations and measurements

    NASA Astrophysics Data System (ADS)

    Tiwari, Kunal; Sharma, Suresh C.; Hozhabri, Nader

    2015-09-01

    Through computer simulations and surface plasmon resonance (SPR) measurements, we establish optimum parameters for the design and fabrication of SPR sensors of high sensitivity, resolution, stability, and long decay-length evanescent fields. We present simulations and experimental SPR data for variety of sensors fabricated by using bimetal (Ag/Au) and multilayer waveguide-coupled Ag/Si3N4/Au structures. The simulations were carried out by using the transfer matrix method in MATLAB environment. Results are presented as functions of the thickness of the metal (Ag or Au) and the waveguide dielectric used in Ag/Si3N4/Au structures. Excellent agreement is observed between the simulations and experiments. For optimized thickness of the Si3N4 waveguide (150 nm), the sensor exhibits very high sensitivity to changes in the refractive index of analytes, Sn≈52°/R I U , extremely high resolution (F W H M ≤0.28° ) , and long penetration depth of evanescent fields (δ≥305 n m ) .

  10. Half-Cell Potential Analysis of an Ammonia Sensor with the Electrochemical Cell Au | YSZ | Au, V2O5-WO3-TiO2

    PubMed Central

    Schönauer-Kamin, Daniela; Fleischer, Maximilian; Moos, Ralf

    2013-01-01

    Half-cell potentials of the electrochemical cell Au, VWT | YSZ | Au are analyzed in dependence on oxygen and ammonia concentration at 550 °C. One of the gold electrodes is covered with a porous SCR catalyst, vanadia-tungstenia-titania (VWT). The cell is utilized as a potentiometric ammonia gas sensor and provides a semi-logarithmic characteristic curve with a high NH3 sensitivity and selectivity. The analyses of the Au | YSZ and Au, VWT | YSZ half-cells are conducted to describe the non-equilibrium behavior of the sensor device in light of mixed potential theory. Both electrode potentials provide a dependency on the NH3 concentration, whereby VWT, Au | YSZ shows a stronger effect which increases with increasing VWT coverage. The potential shifts in the anodic direction confirm the formation of mixed potentials at both electrodes resulting from electrochemical reactions of O2 and NH3 at the three-phase boundary. Polarization curves indicate Butler-Volmer-type kinetics. Modified polarization curves of the VWT covered electrode show an enhanced anodic reaction and an almost unaltered cathodic reaction. The NH3 dependency is dominated by the VWT coverage and it turns out that the catalytic properties of the VWT thick film are responsible for the electrode potential shift. PMID:23575035

  11. Demonstration of a refractometric sensor based on an optical micro-fiber three-beam interferometer

    NASA Astrophysics Data System (ADS)

    Han, Chunyang; Ding, Hui; Lv, Fangxing

    2014-12-01

    With diameter close to the wavelength of the guided light and high index contrast between the fiber and the surrounding, an optical micro-fiber shows a variety of interesting waveguiding properties, including widely tailorable optical confinement, strong evanescent fields and waveguide dispersion. Among various micro-fiber applications, optical sensing has been attracting increasing research interest due to its possibilities of realizing miniaturized fiber optic sensors with small footprint, high sensitivity, and low optical power consumption. Typical micro-fiber based sensing structures, including Michelson interferometer, Mach-Zenhder interferometer, Fabry-Perot interferometer, micro-fiber ring resonator, have been proposed. The sensitivity of these structures heavily related to the fraction of evanescent field outside micro-fiber. In this paper, we report the first theoretical and experimental study of a new type of refractometric sensor based on micro-fiber three-beam interferometer. Theoretical and experimental analysis reveals that the sensitivity is not only determined by the fraction of evanescent field outside the micro-fiber but also related to the values of interferometric arms. The sensitivity can be enhanced significantly when the effective lengths of the interferometric arms tends to be equal. We argue that this has great potential for increasing the sensitivity of refractive index detection.

  12. Demonstration of a refractometric sensor based on an optical micro-fiber three-beam interferometer.

    PubMed

    Han, Chunyang; Ding, Hui; Lv, Fangxing

    2014-12-16

    With diameter close to the wavelength of the guided light and high index contrast between the fiber and the surrounding, an optical micro-fiber shows a variety of interesting waveguiding properties, including widely tailorable optical confinement, strong evanescent fields and waveguide dispersion. Among various micro-fiber applications, optical sensing has been attracting increasing research interest due to its possibilities of realizing miniaturized fiber optic sensors with small footprint, high sensitivity, and low optical power consumption. Typical micro-fiber based sensing structures, including Michelson interferometer, Mach-Zenhder interferometer, Fabry-Perot interferometer, micro-fiber ring resonator, have been proposed. The sensitivity of these structures heavily related to the fraction of evanescent field outside micro-fiber. In this paper, we report the first theoretical and experimental study of a new type of refractometric sensor based on micro-fiber three-beam interferometer. Theoretical and experimental analysis reveals that the sensitivity is not only determined by the fraction of evanescent field outside the micro-fiber but also related to the values of interferometric arms. The sensitivity can be enhanced significantly when the effective lengths of the interferometric arms tends to be equal. We argue that this has great potential for increasing the sensitivity of refractive index detection.

  13. Graphene-Based Long-Period Fiber Grating Surface Plasmon Resonance Sensor for High-Sensitivity Gas Sensing

    PubMed Central

    Wei, Wei; Nong, Jinpeng; Zhang, Guiwen; Tang, Linlong; Jiang, Xiao; Chen, Na; Luo, Suqin; Lan, Guilian; Zhu, Yong

    2016-01-01

    A graphene-based long-period fiber grating (LPFG) surface plasmon resonance (SPR) sensor is proposed. A monolayer of graphene is coated onto the Ag film surface of the LPFG SPR sensor, which increases the intensity of the evanescent field on the surface of the fiber and thereby enhances the interaction between the SPR wave and molecules. Such features significantly improve the sensitivity of the sensor. The experimental results demonstrate that the sensitivity of the graphene-based LPFG SPR sensor can reach 0.344 nm%−1 for methane, which is improved 2.96 and 1.31 times with respect to the traditional LPFG sensor and Ag-coated LPFG SPR sensor, respectively. Meanwhile, the graphene-based LPFG SPR sensor exhibits excellent response characteristics and repeatability. Such a SPR sensing scheme offers a promising platform to achieve high sensitivity for gas-sensing applications. PMID:28025483

  14. Micro-optomechanical sensor for optical connection in the near field

    NASA Astrophysics Data System (ADS)

    Belier, B.; Santoso, A.; Bonnafe, J.; Nicu, L.; Temple-Boyer, P.; Bergaud, C.

    2000-09-01

    A micro-optomechanical sensor has been used to collect and carry optical information at the nanometer scale. This simple device consists of a SiNx microfabricated cantilever used simultaneously as an atomic-force microscope (AFM) probe and optical waveguide. When approaching the micro-optical cantilever close to the surface, the tip converts evanescent waves into radiative waves that propagate within the cantilever over long distances. Since the device is also employed as an AFM probe, mechanical contact is fully controlled as the tip approaches the surface, thus avoiding any crash. This sensor has been used to collect optical information from an optical fiber in the near field.

  15. High angular sensitivity thin film tin oxide sensor

    NASA Astrophysics Data System (ADS)

    Kaur, Davinder; Madaan, Divya; Sharma, V. K.; Kapoor, A.

    2016-05-01

    We present theoretical anlaysis of a thin film SnO2 (Tin Oxide) sensor for the measurement of variation in the refractive index of the bulk media. It is based on lossy mode resonance between the absorbing thin film lossy modes and the evanescent wave. Also the addition of low index dielectric matching layer between the prism and the lossy waveguiding layer future increase the angular sensitivity and produce an efficient refractive index sensor. The angular interrogation is done and obtained sensitivity is 110 degree/RIU. Theoretical analysis of the proposed sensor based on Fresnel reflection coefficients is presented. This enhanced sensitivity will further improve the monitoring of biomolecular interactions and the higher sensitivity of the proposed configurations makes it to be a much better option to be employed for biosensing applications.

  16. All-polymer whispering gallery mode sensor system.

    PubMed

    Petermann, Ann Britt; Varkentin, Arthur; Roth, Bernhard; Morgner, Uwe; Meinhardt-Wollweber, Merve

    2016-03-21

    Sensors based on whispering gallery modes have been extensively investigated with respect to their possible application as physical or biological sensors. Instead of using a single resonator, we use an all polymer resonator array as sensing element. A tunable narrowband laser is coupled into a PMMA plate serving as an optical wave guide. PMMA spheres are placed in the evanescent field on the surface of the plate. Due to small size variations, some spheres are in resonance at a given wavelength while others are not. We show that this device is well suited for the determination of an unknown wavelength or for temperature measurements. Moreover, we discuss several general aspects of the sensor concept such as the number and size of sensing elements which are necessary for a correct measurement result, or the maximum acceptable linewidth of the laser.

  17. An Electromagnetic Sensor with a Metamaterial Lens for Nondestructive Evaluation of Composite Materials

    PubMed Central

    Savin, Adriana; Steigmann, Rozina; Bruma, Alina; Šturm, Roman

    2015-01-01

    This paper proposes the study and implementation of a sensor with a metamaterial (MM) lens in electromagnetic nondestructive evaluation (eNDE). Thus, the use of a new type of MM, named Conical Swiss Rolls (CSR) has been proposed. These structures can serve as electromagnetic flux concentrators in the radiofrequency range. As a direct application, plates of composite materials with carbon fibers woven as reinforcement and polyphenylene sulphide as matrix with delaminations due to low energy impacts were examined. The evaluation method is based on the appearance of evanescent modes in the space between carbon fibers when the sample is excited with a transversal magnetic along z axis (TMz) polarized electromagnetic field. The MM lens allows the transmission and intensification of evanescent waves. The characteristics of carbon fibers woven structure became visible and delaminations are clearly emphasized. The flaws can be localized with spatial resolution better than λ/2000. PMID:26151206

  18. An Electromagnetic Sensor with a Metamaterial Lens for Nondestructive Evaluation of Composite Materials.

    PubMed

    Savin, Adriana; Steigmann, Rozina; Bruma, Alina; Šturm, Roman

    2015-07-03

    This paper proposes the study and implementation of a sensor with a metamaterial (MM) lens in electromagnetic nondestructive evaluation (eNDE). Thus, the use of a new type of MM, named Conical Swiss Rolls (CSR) has been proposed. These structures can serve as electromagnetic flux concentrators in the radiofrequency range. As a direct application, plates of composite materials with carbon fibers woven as reinforcement and polyphenylene sulphide as matrix with delaminations due to low energy impacts were examined. The evaluation method is based on the appearance of evanescent modes in the space between carbon fibers when the sample is excited with a transversal magnetic along z axis (TMz) polarized electromagnetic field. The MM lens allows the transmission and intensification of evanescent waves. The characteristics of carbon fibers woven structure became visible and delaminations are clearly emphasized. The flaws can be localized with spatial resolution better than λ/2000.

  19. In situ trace analysis of oil in water with mid-infrared fiberoptic chemical sensors.

    PubMed

    Luzinova, Yuliya; Zdyrko, Bogdan; Luzinov, Igor; Mizaikoff, Boris

    2012-02-07

    The determination of trace amounts of oil in water facilitates the forensic analysis on the presence and origin of oil in the aqueous environment. To this end, the present study focuses on direct sensing schemes for quantifying trace amounts of oil in water using mid-infrared (MIR) evanescent field absorption spectroscopy via fiberoptic chemical sensors. MIR transparent silver halide fibers were utilized as optical transducer for interrogating oil-in-water emulsions via the evanescent field emanating from the waveguide surface, and penetrating the surrounding aqueous environment by a couple of micrometers. Unmodified fibers and fibers surface-modified with grafted epoxidized polybutadiene layers enabled the direct detection of crude oil in a deionized water matrix at the ppm level to ppb concentration level, respectively. Thus, direct chemical sensing of crude oil IR signatures without any sample preparation as low as 46 ppb was achieved with a response time of a few seconds.

  20. Effects of representative glucocorticoids on TNFα- and CD40L-induced NF-κB activation in sensor cells.

    PubMed

    Cechin, Sirlene R; Buchwald, Peter

    2014-07-01

    Glucocorticoids are an important class of anti-inflammatory/immunosuppressive drugs. A crucial part of their anti-inflammatory action results from their ability to repress proinflammatory transcription factors such as nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) upon binding to the glucocorticoid receptor (GR). Accordingly, sensor cells quantifying their effect on inflammatory signal-induced NF-κB activation can provide useful information regarding their potencies as well as their transrepression abilities. Here, we report results obtained on their effect in suppressing both the TNFα- and the CD40L-induced activation of NF-κB in sensor cells that contain an NF-κB-inducible SEAP construct. In these cells, we confirmed concentration-dependent NF-κB activation for both TNFα and CD40L at low nanomolar concentrations (EC50). Glucocorticoids tested included hydrocortisone, prednisolone, dexamethasone, loteprednol etabonate, triamcinolone acetonide, beclomethasone dipropionate, and clobetasol propionate. They all caused significant, but only partial inhibition of these activations in concentration-dependent manners that could be well described by sigmoid response-functions. Despite the limitations of only partial maximum inhibitions, this cell-based assay could be used to quantitate the suppressing ability of glucocorticoids (transrepression potency) on the expression of proinflammatory transcription factors caused by two different cytokines in parallel both in a detailed, full dose-response format as well as in a simpler single-dose format. Whereas inhibitory potencies obtained in the TNF assay correlated well with consensus glucocorticoid potencies (receptor-binding affinities, Kd, RBA, at the GR) for all compounds, the non-halogenated steroids (hydrocortisone, prednisolone, and loteprednol etabonate) were about an order of magnitude more potent than expected in the CD40 assay in this system.

  1. A Complete Optical Sensor System Based on a POF-SPR Platform and a Thermo-Stabilized Flow Cell for Biochemical Applications

    PubMed Central

    Cennamo, Nunzio; Chiavaioli, Francesco; Trono, Cosimo; Tombelli, Sara; Giannetti, Ambra; Baldini, Francesco; Zeni, Luigi

    2016-01-01

    An optical sensor platform based on surface plasmon resonance (SPR) in a plastic optical fiber (POF) integrated into a thermo-stabilized flow cell for biochemical sensing applications is proposed. This device has been realized and experimentally tested by using a classic receptor-analyte assay. For this purpose, the gold surface of the POF was chemically modified through the formation of a self-assembling monolayer. The surface robustness of the POF-SPR platform has been tested for the first time thanks to the flow cell. The experimental results show that the proposed device can be successfully used for label-free biochemical sensing. The final goal of this work is to achieve a complete, small-size, simple to use and low cost optical sensor system. The whole system with the flow cell and the optical sensor are extensively described, together with the experimental results obtained with an immunoglobulin G (IgG)/anti-IgG assay. PMID:26861328

  2. Sub-Nanoliter Spectroscopic Gas Sensor

    PubMed Central

    Alfeeli, Bassam; Pickrell, Gary; Wang, Anbo

    2006-01-01

    In this work, a new type of optical fiber based chemical sensor, the sub-nanoliter sample cell (SNSC) based gas sensor, is described and compared to existing sensors designs in the literature. This novel SNSC gas sensor is shown to have the capability of gas detection with a cell volume in the sub-nanoliter range. Experimental results for various configurations of the sensor design are presented which demonstrate the capabilities of the miniature gas sensor.

  3. Improved Cell Sensitivity and Longevity in a Rapid Impedance-based Toxicity Sensor

    DTIC Science & Technology

    2009-01-06

    bovine lung microvessel endothelial cell (BLMVEC) monolayers and iguana heart (IgH-2) cell monolayers could detect nine out of the 12 waterborne...and iguana heart (IgH-2) cell monolayers could detect nine out of the 12 waterborne industrial chemicals, an improvement over the seven chemicals...monolayers and the iguana heart cell (IgH-2) monolayers can improve both the sensitivity of response to toxicants and the longevity of cells in the

  4. Liquid level sensor

    SciTech Connect

    Kulkarni, Atul; Karekar, R.N.; Aiyer, R.C.

    2005-10-15

    The article reports an idea of using a simple, cantilever-type load cell with a rod as a level sensor for continuous liquid level measurements. The sensor is based on the principle of the Archimedes buoyancy principle. The density and geometry of the rod govern the choice of the load cell. The length of the rod is governed by the height of the tank. A series of cyclic tests have demonstrated a highly repeatable response of the sensor. The accuracy of this low-cost sensor is field tested and found to be {+-}0.5% of the full range, for a 10 m level of water in a tank, and is working reliably for the period of 18 months. The sensor range can be easily extended to lower and higher tank heights. The sensor is crowned by its easy installation and calibration.

  5. Glucose Dependency of the Metabolic Pathway of HEK 293 Cells Measured by a Flow-through Type pH/CO2 Sensor System Using ISFETs

    NASA Astrophysics Data System (ADS)

    Yamada, Akira; Mohri, Satoshi; Nakamura, Michihiro; Naruse, Keiji

    Our group previously reported the application of a flow-through type pH/CO2 sensor system designed to evaluate the metabolic activity of cultured cells. The sensor system consists of two ion-sensitive field effect transistors (ISFETs), an ISFET to measure the total pH change and an ISFET enclosed within a gas-permeable silicone tube to measure the pH change attributable to CO2. In that study, we used the system to quantitatively analyze metabolic switching induced by glucose concentration changes in three cultured cell types (bovine arterial endothelium cell (BAEC), human umbilical vein endothelium cell (HUVEC), and rat cardiomuscle cell (RCMC)), and to measure the production rates of total carbonate and free lactic acid in the cultured cells. In every cell type examined, a decrease in the glucose concentration led to an increase in total carbonate, a product of cellular respiration, and a decrease of free lactic acid, a product of glycolysis. There were very significant differences among the cell types, however, in the glucose concentrations at the metabolic switching points. We postulated that the cell has a unique switching point on the metabolic pathway from glycolysis to respiration. In this paper we use our sensor system to evaluate the metabolic switching of human embryonic kidney 293 cells triggered by glucose concentration changes. The superior metabolic pathway switched from glycolysis to respiration when the glucose concentration decreased to about 2 mM. This result was very similar to that obtained in our earlier experiments on HUVECs, but far different from our results on the other two cells types, BAECs and RCMCs. This sensor system will be useful for analyzing cellular metabolism for many applications and will yield novel information on different cell types.

  6. Nondestructive Superresolution Imaging of Defects and Nonuniformities in Metals, Semiconductors, Dielectrics, Composites, and Plants Using Evanescent Microwaves

    NASA Technical Reports Server (NTRS)

    Tabib-Azar, M.; Pathak, P. S.; Ponchak, G.; LeClair, S.

    1999-01-01

    We have imaged and mapped material nonuniformities and defects using microwaves generated at the end of a microstripline resonator with 0.4 micrometer lateral spatial resolution at 1 GHz. Here we experimentally examine the effect of microstripline substrate permittivity, the feedline-to-resonator coupling strength, and probe tip geometry on the spatial resolution of the probe. Carbon composites, dielectrics, semiconductors, metals, and botanical samples were scanned for defects, residual stresses, subsurface features, areas of different film thickness, and moisture content. The resulting evanescent microwave probe (EMP) images are discussed. The main objective of this work is to demonstrate the overall capabilities of the EMP imaging technique as well as to discuss various probe parameters that can be used to design EMPs for different applications.

  7. Optical singularities and power flux in the near-field region of planar evanescent-field superlenses.

    PubMed

    Perez-Molina, Manuel; Carretero, L; Acebal, P; Blaya, S

    2008-11-01

    We rigorously analyze the optical singularities and power flux in the near-field region of the novel superlenses reported in [Science317, 927 (2007)] For this purpose, we derive near-field expressions and a general criterion to classify the optical singularities in the vacuum, which are valid when the (s- or p-polarized) electromagnetic fields are generated by any planar field distribution with Cartesian or azimuthal symmetry. Such general results are particularized to the superlenses [Science317, 927 (2007)], for which we identify a sequence of optical vortices and saddles that arise from evanescent-field interference. While the saddles are always located around the focal region, the vortex locations depend on the source field. The features of the topological connection between vortices and saddles are also discussed.

  8. Planar evanescent microwave imaging probes for nondestructive evaluation of materials with very high spatial resolutions and scan rates

    NASA Astrophysics Data System (ADS)

    Tabib-Azar, Massood; Wang, Ruoxun

    2001-04-01

    Local probes, such as scanning tunneling, atomic force, near-field scanning, and evanescent microwave microscopes are important material characterization tools with nearly atomic spatial resolutions capable of operating in many different environments. All these probes are currently laboratory tools with limited real-time manufacturing applications because of their low speed. EMM has the greatest potential of acquiring higher scanning speed because it does not require an intimate contact with the material surface. EMM is also capable of characterizing a variety of organic and inorganic materials including metals, semiconductors, and insulators over a wide range of frequencies and length scales. Here we discuss the application of parallel EMMs in monitoring thin-film quality in real-time and in situ. We address data management and mining issues to deal with the very large data bandwidth generated by EMM.

  9. Optimized sensitivity of Silicon-on-Insulator (SOI) strip waveguide resonator sensor

    PubMed Central

    TalebiFard, Sahba; Schmidt, Shon; Shi, Wei; Wu, WenXuan; Jaeger, Nicolas A. F.; Kwok, Ezra; Ratner, Daniel M.; Chrostowski, Lukas

    2017-01-01

    Evanescent field sensors have shown promise for biological sensing applications. In particular, Silicon-on-Insulator (SOI)-nano-photonic based resonator sensors have many advantages for lab-on-chip diagnostics, including high sensitivity for molecular detection and compatibility with CMOS foundries for high volume manufacturing. We have investigated the optimum design parameters within the fabrication constraints of Multi-Project Wafer (MPW) foundries that result in the highest sensitivity for a resonator sensor. We have demonstrated the optimum waveguide thickness needed to achieve the maximum bulk sensitivity with SOI-based resonator sensors to be 165 nm using the quasi-TM guided mode. The closest thickness offered by MPW foundry services is 150 nm. Therefore, resonators with 150 nm thick silicon waveguides were fabricated resulting in sensitivities as high as 270 nm/RIU, whereas a similar resonator sensor with a 220 nm thick waveguide demonstrated sensitivities of approximately 200 nm/RIU. PMID:28270963

  10. Load-cell based characterization system for a "Violin-Mode" shadow-sensor in advanced LIGO suspensions

    NASA Astrophysics Data System (ADS)

    Lockerbie, N. A.; Tokmakov, K. V.

    2016-07-01

    The background to this work was a prototype shadow sensor, which was designed for retro-fitting to an advanced LIGO (Laser Interferometer Gravitational wave Observatory) test-mass/mirror suspension, in which 40 kg test-mass/mirrors are each suspended by four approximately 600 mm long by 0.4 mm diameter fused-silica suspension fibres. The shadow sensor comprised a LED source of Near InfraRed (NIR) radiation and a rectangular silicon photodiode detector, which, together, were to bracket the fibre under test. The aim was to detect transverse Violin-Mode resonances in the suspension fibres. Part of the testing procedure involved tensioning a silica fibre sample and translating it transversely through the illuminating NIR beam, so as to measure the DC responsivity of the detection system to fibre displacement. However, an equally important part of the procedure, reported here, was to keep the fibre under test stationary within the beam, whilst trying to detect low-level AC Violin-Mode resonances excited on the fibre, in order to confirm the primary function of the sensor. Therefore, a tensioning system, incorporating a load-cell readout, was built into the test fibre's holder. The fibre then was excited by a signal generator, audio power amplifier, and distant loudspeaker, and clear resonances were detected. A theory for the expected fundamental resonant frequency as a function of fibre tension was developed and is reported here, and this theory was found to match closely with the detected resonant frequencies as they varied with tension. Consequently, the resonances seen were identified as being proper Violin-Mode fundamental resonances of the fibre, and the operation of the Violin-Mode detection system was validated.

  11. Load-cell based characterization system for a "Violin-Mode" shadow-sensor in advanced LIGO suspensions.

    PubMed

    Lockerbie, N A; Tokmakov, K V

    2016-07-01

    The background to this work was a prototype shadow sensor, which was designed for retro-fitting to an advanced LIGO (Laser Interferometer Gravitational wave Observatory) test-mass/mirror suspension, in which 40 kg test-mass/mirrors are each suspended by four approximately 600 mm long by 0.4 mm diameter fused-silica suspension fibres. The shadow sensor comprised a LED source of Near InfraRed (NIR) radiation and a rectangular silicon photodiode detector, which, together, were to bracket the fibre under test. The aim was to detect transverse Violin-Mode resonances in the suspension fibres. Part of the testing procedure involved tensioning a silica fibre sample and translating it transversely through the illuminating NIR beam, so as to measure the DC responsivity of the detection system to fibre displacement. However, an equally important part of the procedure, reported here, was to keep the fibre under test stationary within the beam, whilst trying to detect low-level AC Violin-Mode resonances excited on the fibre, in order to confirm the primary function of the sensor. Therefore, a tensioning system, incorporating a load-cell readout, was built into the test fibre's holder. The fibre then was excited by a signal generator, audio power amplifier, and distant loudspeaker, and clear resonances were detected. A theory for the expected fundamental resonant frequency as a function of fibre tension was developed and is reported here, and this theory was found to match closely with the detected resonant frequencies as they varied with tension. Consequently, the resonances seen were identified as being proper Violin-Mode fundamental resonances of the fibre, and the operation of the Violin-Mode detection system was validated.

  12. Novel glucose fiber sensor combining ThFBG with GOD

    NASA Astrophysics Data System (ADS)

    Li, Mengmeng; Zhou, Ciming; Fan, Dian; Ou, Yiwen

    2016-10-01

    We propose a novel glucose fiber optic sensor combining a thinned cladding fiber Bragg grating (ThFBG) with glucose oxidase (GOD). By immobilizing GOD on the surface of a ThFBG, the fabricated sensor can obtain a high specificity to glucose. Because of the evanescent field, the sensor is very sensitive to the ambient refractive index change arising from the catalytic reaction between glucose and GOD. A four-level fiber model was simulated and verified the precision of the sensing principle. Two methods, glutaraldehyde crosslinking method (GCM) and 3-aminopropyl triethoxysilane covalent coupling method (ATCCM), were experimentally utilized to immobilize GOD. And sensor fabricated with the method ATCCM shows a measurement range of 0-0.82 mg/mL which is better than the sensor fabricated with the method GCM with measurement range of 0-0.67 mg/mL under the same condition. By using ATCCM to immobilize GOD with different concentrations, three sensors were fabricated and used for glucose measurement by monitoring the Bragg wavelength (λb) shifts, the results indicate a good linear relationship between wavelength shift and glucose concentration within a specific range, and the measurement range increases as GOD concentration increases. The highest sensitivity of sensor reaches up to 0.0549 nm/(mg.mL-1). The proposed sensor has distinct advantages in sensing structure, cost and specificity.

  13. Evaluation and refinement of a field-portable drinking water toxicity sensor utilizing electric cell-substrate impedance sensing and a fluidic biochip.

    PubMed

    Widder, Mark W; Brennan, Linda M; Hanft, Elizabeth A; Schrock, Mary E; James, Ryan R; van der Schalie, William H

    2015-07-01

    The US Army's need for a reliable and field-portable drinking water toxicity sensor was the catalyst for the development and evaluation of an electric cell-substrate impedance sensing (ECIS) device. Water testing technologies currently available to soldiers in the field are analyte-specific and have limited capabilities to detect broad-based water toxicity. The ECIS sensor described here uses rainbow trout gill epithelial cells seeded on fluidic biochips to measure changes in impedance for the detection of possible chemical contamination of drinking water supplies. Chemicals selected for testing were chosen as representatives of a broad spectrum of toxic industrial compounds. Results of a US Environmental Protection Agency (USEPA)-sponsored evaluation of the field portable device were similar to previously published US Army testing results of a laboratory-based version of the same technology. Twelve of the 18 chemicals tested following USEPA Technology Testing and Evaluation Program procedures were detected by the ECIS sensor within 1 h at USEPA-derived human lethal concentrations. To simplify field-testing methods further, elimination of a procedural step that acclimated cells to serum-free media streamlined the test process with only a slight loss of chemical sensitivity. For field use, the ECIS sensor will be used in conjunction with an enzyme-based sensor that is responsive to carbamate and organophosphorus pesticides.

  14. A targetable fluorescent sensor reveals that copper-deficient SCO1 and SCO2 patient cells prioritize mitochondrial copper homeostasis.

    PubMed

    Dodani, Sheel C; Leary, Scot C; Cobine, Paul A; Winge, Dennis R; Chang, Christopher J

    2011-06-08

    We present the design, synthesis, spectroscopy, and biological applications of Mitochondrial Coppersensor-1 (Mito-CS1), a new type of targetable fluorescent sensor for imaging exchangeable mitochondrial copper pools in living cells. Mito-CS1 is a bifunctional reporter that combines a Cu(+)-responsive fluorescent platform with a mitochondrial-targeting triphenylphosphonium moiety for localizing the probe to this organelle. Molecular imaging with Mito-CS1 establishes that this new chemical tool can detect changes in labile mitochondrial Cu(+) in a model HEK 293T cell line as well as in human fibroblasts. Moreover, we utilized Mito-CS1 in a combined imaging and biochemical study in fibroblasts derived from patients with mutations in the two synthesis of cytochrome c oxidase 1 and 2 proteins (SCO1 and SCO2), each of which is required for assembly and metalation of functionally active cytochrome c oxidase (COX). Interestingly, we observe that although defects in these mitochondrial metallochaperones lead to a global copper deficiency at the whole cell level, total copper and exchangeable mitochondrial Cu(+) pools in SCO1 and SCO2 patient fibroblasts are largely unaltered relative to wild-type controls. Our findings reveal that the cell maintains copper homeostasis in mitochondria even in situations of copper deficiency and mitochondrial metallochaperone malfunction, illustrating the importance of regulating copper stores in this energy-producing organelle.

  15. Highly Dispersed NiO Nanoparticles Decorating graphene Nanosheets for Non-enzymatic Glucose Sensor and Biofuel Cell

    PubMed Central

    Zeng, Guisheng; Li, Weiping; Ci, Suqin; Jia, Jingchun; Wen, Zhenhai

    2016-01-01

    Nickel oxide-decorated graphene nanosheet (NiO/GNS), as a novel non-enzymatic electrocatalyst for glucose oxidation reaction (GOR), was synthesized through a facile hydrothermal route followed by the heat treatment. The successful synthesis of NiO/GNS was characterized by a series of techniques including XRD, BET, SEM and TEM. Significantly, the NiO/GNS catalyst show excellent catalytic activity toward GOR, and was employed to develop a sensitive non-enzymatic glucose sensor. The developed glucose sensor could response to glucose in a wide range from 5 μM–4.2 mM with a low detection limit (LOD) of 5.0 μM (S/N = 3). Importantly, compared with bare NiO, the catalytic activity of NiO/GNS was much higher. The reason might be that the 2D structure of graphene could prevent the aggregation of NiO and facilitate the electron transfer at electrode interface. Moreover, the outstanding catalytic activity of NiO/GNS was further demonstrated by applying it to construct a biofuel cell using glucose as fuel, which exhibited high stability and current density. PMID:27805039

  16. Highly Dispersed NiO Nanoparticles Decorating graphene Nanosheets for Non-enzymatic Glucose Sensor and Biofuel Cell

    NASA Astrophysics Data System (ADS)

    Zeng, Guisheng; Li, Weiping; Ci, Suqin; Jia, Jingchun; Wen, Zhenhai

    2016-11-01

    Nickel oxide-decorated graphene nanosheet (NiO/GNS), as a novel non-enzymatic electrocatalyst for glucose oxidation reaction (GOR), was synthesized through a facile hydrothermal route followed by the heat treatment. The successful synthesis of NiO/GNS was characterized by a series of techniques including XRD, BET, SEM and TEM. Significantly, the NiO/GNS catalyst show excellent catalytic activity toward GOR, and was employed to develop a sensitive non-enzymatic glucose sensor. The developed glucose sensor could response to glucose in a wide range from 5 μM–4.2 mM with a low detection limit (LOD) of 5.0 μM (S/N = 3). Importantly, compared with bare NiO, the catalytic activity of NiO/GNS was much higher. The reason might be that the 2D structure of graphene could prevent the aggregation of NiO and facilitate the electron transfer at electrode interface. Moreover, the outstanding catalytic activity of NiO/GNS was further demonstrated by applying it to construct a biofuel cell using glucose as fuel, which exhibited high stability and current density.

  17. Inhibition of charge recombination for enhanced dye-sensitized solar cells and self-powered UV sensors by surface modification

    NASA Astrophysics Data System (ADS)

    Chu, Liang; Qin, Zhengfei; Liu, Wei; Ma, Xin'guo

    2016-12-01

    The surface modification to inhibit charge recombination was utilized in dye-sensitized solar cells (DSSCs) and self-powered ultraviolet (UV) sensors based on SnO2 hierarchical microspheres by TiO2 modification. For DSSCs with SnO2 photoelectrodes modified by TiO2, the power conversion efficiency (PCE) was improved from 1.40% to 4.15% under standard AM 1.5G illumination (100 mW/cm2). The electrochemical impedance spectroscopy and open-circuit voltage decay measurements indicated that the charge recombination was effectively inhibited, resulting in long electron lifetime. For UV sensors with SnO2 photoelectrodes modified by TiO2 layer, the self-powered property was more obvious, and the sensitivity and response time were enhanced from 91 to 6229 and 0.15 s to 0.055 s, respectively. The surface modification can engineer the interface energy to inhibit charge recombination, which is a desirable approach to improve the performance of photoelectric nanodevice.

  18. Use of Multi-Functional Flexible Micro-Sensors for in situ Measurement of Temperature, Voltage and Fuel Flow in a Proton Exchange Membrane Fuel Cell

    PubMed Central

    Lee, Chi-Yuan; Chan, Pin-Cheng; Lee, Chung-Ju

    2010-01-01

    Temperature, voltage and fuel flow distribution all contribute considerably to fuel cell performance. Conventional methods cannot accurately determine parameter changes inside a fuel cell. This investigation developed flexible and multi-functional micro sensors on a 40 μm-thick stainless steel foil substrate by using micro-electro-mechanical systems (MEMS) and embedded them in a proton exchange membrane fuel cell (PEMFC) to measure the temperature, voltage and flow. Users can monitor and control in situ the temperature, voltage and fuel flow distribution in the cell. Thereby, both fuel cell performance and lifetime can be increased. PMID:22163545

  19. Use of multi-functional flexible micro-sensors for in situ measurement of temperature, voltage and fuel flow in a proton exchange membrane fuel cell.

    PubMed

    Lee, Chi-Yuan; Chan, Pin-Cheng; Lee, Chung-Ju

    2010-01-01

    Temperature, voltage and fuel flow distribution all contribute considerably to fuel cell performance. Conventional methods cannot accurately determine parameter changes inside a fuel cell. This investigation developed flexible and multi-functional micro sensors on a 40 μm-thick stainless steel foil substrate by using micro-electro-mechanical systems (MEMS) and embedded them in a proton exchange membrane fuel cell (PEMFC) to measure the temperature, voltage and flow. Users can monitor and control in situ the temperature, voltage and fuel flow distribution in the cell. Thereby, both fuel cell performance and lifetime can be increased.

  20. Multiple model estimator based detection of abnormal cell overheating in a Li-ion battery string with minimum number of temperature sensors

    NASA Astrophysics Data System (ADS)

    Lystianingrum, Vita; Hredzak, Branislav; Agelidis, Vassilios G.

    2015-01-01

    This paper proposes modeling of abnormal cell overheating caused by internal short circuit in a cell of a Li-ion battery string by augmenting the cell state space model with unknown input disturbance. Furthermore, with minimum number of temperature sensors, in order to identify which of the cells in the string is experiencing the abnormal overheating, a multiple model estimator (MME) is used. Simulation results demonstrate that the proposed MME can detect the abnormally overheating cell as well as quickly detect that an abnormal overheating event occurred in the battery string.

  1. Real-time and high-throughput analysis of mitochondrial metabolic states in living cells using genetically encoded NAD(+)/NADH sensors.

    PubMed

    Zhao, Yuzheng; Yang, Yi

    2016-11-01

    Mitochondria are central organelles that regulate cellular bioenergetics, biosynthesis, and signaling processes. NADH, a key player in cell metabolism, is often considered as a marker of mitochondrial function. However, traditional methods for NADH measurements are either destructive or unable to distinguish between NADH and NADPH. In contrast to traditional methods, genetically encoded NADH sensors can be used for the real-time tracking and quantitative measurement of subcellular NADH levels in living cells. Therefore, these sensors provide innovative tools and address the limitations of current techniques. We herein summarize the properties of different types of recently developed NADH biosensors, discuss their advantages and disadvantages, and focus on the high-throughput analysis of mitochondrial function by using highly responsive NAD(+)/NADH sensors.

  2. Epithelial tricellular junctions act as interphase cell shape sensors to orient mitosis.

    PubMed

    Bosveld, Floris; Markova, Olga; Guirao, Boris; Martin, Charlotte; Wang, Zhimin; Pierre, Anaëlle; Balakireva, Maria; Gaugue, Isabelle; Ainslie, Anna; Christophorou, Nicolas; Lubensky, David K; Minc, Nicolas; Bellaïche, Yohanns

    2016-02-25

    The orientation of cell division along the long axis of the interphase cell--the century-old Hertwig's rule--has profound roles in tissue proliferation, morphogenesis, architecture and mechanics. In epithelial tissues, the shape of the interphase cell is influenced by cell adhesion, mechanical stress, neighbour topology, and planar polarity pathways. At mitosis, epithelial cells usually adopt a rounded shape to ensure faithful chromosome segregation and to promote morphogenesis. The mechanisms underlying interphase cell shape sensing in tissues are therefore unknown. Here we show that in Drosophila epithelia, tricellular junctions (TCJs) localize force generators, pulling on astral microtubules and orienting cell division via the Dynein-associated protein Mud independently of the classical Pins/Gαi pathway. Moreover, as cells round up during mitosis, TCJs serve as spatial landmarks, encoding information about interphase cell shape anisotropy to orient division in the rounded mitotic cell. Finally, experimental and simulation data show that shape and mechanical strain sensing by the TCJs emerge from a general geometric property of TCJ distributions in epithelial tissues. Thus, in addition to their function as epithelial barrier structures, TCJs serve as polarity cues promoting geometry and mechanical sensing in epithelial tissues.

  3. Bioinspired solar water splitting, sensitized solar cells, and ultraviolet sensor based on semiconductor nanocrystal antenna/graphene nanoassemblies

    NASA Astrophysics Data System (ADS)

    Chang, Haixin; Lv, Xiaojun; Zheng, Zijian; Wu, Hongkai

    2011-11-01

    Graphene, two-dimensional carbon crystal with only one atom thickness, provides a general platform for nanoscale even atomic scale optoelectronics and photonics. Graphene has many advantages for optoelectronics such as high conductivity, high electronic mobility, flexibility and transparency. However, graphene also has disadvantages such as low light absorption which are unfavorable for optoelectronic devices. On the other hand, many natural photonic systems provide wonderful solution to enhance light absorption for solar energy harvesting and conversion, such as chlorophyll in green plants. Herein, learning from nature, we described bioinspired photocatalytic solar-driven water splitting, sensitized solar cells and ultraviolet optoelectronic sensors enabled by introducing photosensitive semiconductor nanocrystal antenna to graphene for constructing a series of graphene/nanocrystal nanoassemblies. We have demonstrated that high performance optoelectronic devices can come true with the introducing of photosensitive nanocrystal antenna elements.

  4. Bioinspired solar water splitting, sensitized solar cells, and ultraviolet sensor based on semiconductor nanocrystal antenna/graphene nanoassemblies

    NASA Astrophysics Data System (ADS)

    Chang, Haixin; Lv, Xiaojun; Zheng, Zijian; Wu, Hongkai

    2012-02-01

    Graphene, two-dimensional carbon crystal with only one atom thickness, provides a general platform for nanoscale even atomic scale optoelectronics and photonics. Graphene has many advantages for optoelectronics such as high conductivity, high electronic mobility, flexibility and transparency. However, graphene also has disadvantages such as low light absorption which are unfavorable for optoelectronic devices. On the other hand, many natural photonic systems provide wonderful solution to enhance light absorption for solar energy harvesting and conversion, such as chlorophyll in green plants. Herein, learning from nature, we described bioinspired photocatalytic solar-driven water splitting, sensitized solar cells and ultraviolet optoelectronic sensors enabled by introducing photosensitive semiconductor nanocrystal antenna to graphene for constructing a series of graphene/nanocrystal nanoassemblies. We have demonstrated that high performance optoelectronic devices can come true with the introducing of photosensitive nanocrystal antenna elements.

  5. Enhanced response of microbial fuel cell using sulfonated poly ether ether ketone membrane as a biochemical oxygen demand sensor.

    PubMed

    Ayyaru, Sivasankaran; Dharmalingam, Sangeetha

    2014-03-25

    The present study is focused on the development of single chamber microbial fuel cell (SCMFC) using sulfonated poly ether ether ketone (SPEEK) membrane to determine the biochemical oxygen demand (BOD) matter present in artificial wastewater (AW). The biosensor produces a good linear relationship with the BOD concentration up to 650 ppm when using artificial wastewater. This sensing range was 62.5% higher than that of Nafion(®). The most serious problem in using MFC as a BOD sensor is the oxygen diffusion into the anode compartment, which consumes electrons in the anode compartment, thereby reducing the coulomb yield and reducing the electrical signal from the MFC. SPEEK exhibited one order lesser oxygen permeability than Nafion(®), resulting in low internal resistance and substrate loss, thus improving the sensing range of BOD. The system was further improved by making a double membrane electrode assembly (MEA) with an increased electrode surface area which provide high surface area for electrically active bacteria.

  6. Transepithelial projections from basal cells are luminal sensors in pseudostratified epithelia

    PubMed Central

    Shum, Winnie Wai Chi; Silva, Nicolas Da; McKee, Mary; Smith, Peter J.S.; Brown, Dennis; Breton, Sylvie

    2008-01-01

    Basal cells are by definition located on the basolateral side of several epithelia, and they have never been observed reaching the lumen. Using high-resolution 3D confocal imaging, we report that basal cells extend long and slender cytoplasmic projections that not only reach towards the lumen but can cross the tight junction barrier in some epithelia of the male reproductive and respiratory tracts. In this way, the basal cell plasma membrane is exposed to the luminal environment. In the epididymis, in which luminal acidification is crucial for sperm maturation and storage, these projections contain the angiotensin II type 2 receptor (AGTR2). Activation of AGTR2 by luminal angiotensin II, increases proton secretion by adjacent clear cells, which are devoid of AGTR2. We propose a new paradigm in which basal cells scan and sense the luminal environment of pseudostratified epithelia, and modulate epithelial function by a mechanism involving cross-talk with other epithelial cells. PMID:19070580

  7. Paper-based cell impedance sensor and its application for cytotoxic evaluation

    NASA Astrophysics Data System (ADS)

    Yu, Chunmei; Wang, Qiuhong; Li, Weibo; Li, Yubin; Liu, Shuxian; Bao, Ning; Gu, Haiying

    2015-08-01

    Disposable analytical devices for developing sensitive and label-free monitoring of cancerous cells would be attractive for cancer research. Here, paper-based electroanalytical devices based on impedance spectrometry were applied for the study of K562 cells and the toxic effect of anticancer drugs. The proposed device integrating gold nanorods modified ITO electrodes could provide a biocompatible surface for immobilization of living cells maintaining their bioactivity. The impedance results exhibited good correlation to the logarithmic value of cell numbers ranging from 7.5 × 102 to 3.9 × 106 cells mL-1 with a detection limit of 500 cells mL-1. Furthermore, this strategy was used to evaluate the cytotoxic effects of arsenic trioxide and cyclophosphamide. Results obtained by the impedimetric method correlate well with the conventional cell viability assay. Cells exposed to drugs exhibited a prominent reduction of impedance data, showing an inverse dose-dependent relationship. This simple, cost-effective and portable paper-based electrochemical analytical device could provide a new impedance platform for applications in monitoring cell behavior, pharmacological studies and toxicological analyses.

  8. Ratiometric fluorescent sensor based on inhibition of resonance for detection of cadmium in aqueous solution and living cells.

    PubMed

    Xue, Lin; Li, Guoping; Liu, Qing; Wang, Huanhuan; Liu, Chun; Ding, Xunlei; He, Shenggui; Jiang, Hua

    2011-04-18

    Although cadmium has been recognized as a highly toxic heavy metal and poses many detrimental effects on human health, the Cd(2+)-uptake and nosogenesis mechanisms are still insufficiently understood, mainly because of the lack of facile analytical methods for monitoring changes in the environmental and intracellular Cd(2+) concentrations with high spatial and temporal reliability. To this end, we present the design, synthesis, and photophysical properties of a cadmium sensor, DQCd1 based on the fluorophore 4-isobutoxy-6-(dimethylamino)-8-methoxyquinaldine (model compound 1). Preliminary investigations indicate that 1 could be protonated under neutral media and yield a resonance process over the quinoline fluorophore. Upon excitation at 405 nm, 1 shows a strong fluorescence emission at 554 nm with a quantum yield of 0.17. Similarly, DQCd1 bears properties comparable to its precursor. It exhibits fluorescence emission at 558 nm (Φ(f) = 0.15) originating from the monocationic species under physiological conditions. Coordination with Cd(2+) causes quenching of the emission at 558 nm and simultaneously yields a significant hypsochromic shift of the emission maximum to 495 nm (Φ(f) = 0.11) due to inhibition of the resonance process. Thus, a single-excitation, dual-emission ratiometric measurement with a large blue shift in emission (Δλ = 63 nm) and remarkable changes in the ratio (F(495 nm)/F(558 nm)) of the emission intensity (R/R(0) up to 15-fold) is established. Moreover, the sensor DQCd1 exhibits very high sensitivity for Cd(2+) (K(d) = 41 pM) and excellent selectivity response for Cd(2+) over other heavy- and transition-metal ions and Na(+), K(+), Mg(2+), and Ca(2+) at the millimolar level. Therefore, DQCd1 can act as a ratiometric fluorescent sensor for Cd(2+) through inhibition of the resonance process. Confocal microscopy and cytotoxicity experiments indicate that DQCd1 is cell-permeable and noncytotoxic under our experimental conditions. It can indeed

  9. Laser intensity modulated real time monitoring cell growth sensor for bioprocess applications

    NASA Astrophysics Data System (ADS)

    Kishore, P.; Babu, P. Ravindra; Devi, V. Rama; Maunika, T.; Soujanya, P.; Kishore, P. V. N.; Dinakar, D.

    2016-04-01

    This article proposes an optical method for monitoring the growth of Escherichia coli in Luria Bertani medium and Saccharomyces cereviciae in YPD. Suitable light is selected which on interaction with the analyte under consideration, gets adsorption / scattered. Required electronic circuitry is designed to drive the laser source and to detect the intensity of light using Photo-detector. All these components are embedded and arranged in a proper way and monitored the growth of the microbs in real time. The sensors results are compared with standard techniques such as colorimeter, Nephelometer and hemocytometer. The experimental results are in good agreement with the existed techniques and well suitable for real time monitoring applications of the growth of the microbs.

  10. A Fluidic Cell Embedded Electromagnetic Wave Sensor for Online Indication of Neurological Impairment during Surgical Procedures

    NASA Astrophysics Data System (ADS)

    Blakey, R. T.; Mason, A.; Al-Shamma'a, A. I.

    2013-06-01

    Lactate is known to be an indicator of neurological impairment during aortic aneurysm surgery. It is suggested that cerebrospinal fluid removed during such surgery could provide useful information in this regard. Medical professionals find the prospect of online detection of such analytes exciting, as current practice is time consuming and leads to multiple invasive procedures. Advancing from the current laboratory based analysis techniques to online methods could provide the basis for improved treatment regimes, better quality of care, and enhanced resource efficiency within hospitals. Accordingly, this article considers the use of a low power fluidic system with embedded electromagnetic wave sensor to detect varying lactate concentrations. Results are promising over the physiological range of 0 - 20 mmol/L with a calibration curve demonstrating an R2 value > 0.98.

  11. An integrated micro-volume fiber-optic sensor for oxygen determination in exhaled breath based on iridium(III) complexes immobilized in fluorinated xerogels.

    PubMed

    Xiong, Yan; Ye, Zhongbin; Xu, Jing; Zhu, Yuanqiang; Chen, Chen; Guan, Yafeng

    2013-03-21

    A novel integrated fiber-optic sensor with micro detection volume is developed and evaluated for O(2) determination on a breath-by-breath basis in human health monitoring applications. The sensing element was fabricated by dip-coating an uncladded optical fiber with [Ir(piq)(2)(acac)]-doped hybrid fluorinated ORMOSIL (organically modified silicate) film, which was prepared from 3,3,3-trifluoropropyltrimethoxysilane (TFP-TriMOS) and n-propyltrimethoxysilane (n-propyl-TriMOS). The sensor was then constructed by inserting the prepared optical fiber into a transparent capillary. A microchannel formed between the optical fiber and the capillary inner wall acted as a flow cell for the sample flowing through. The evanescent wave (EW) field produced on the fiber core surface can excite the O(2)-sensitive fluorophores of [Ir(piq)(2)(acac)] to produce emission fluorescence. O(2) can be sensed by its quenching effect on the emission fluorescence intensity. Spectroscopic properties have been characterized by FTIR and fluorescence measurements. Stern-Volmer and Demas models were both employed to analyse the sensor sensitivity, which is 13.0 with the LOD = 0.009% (3σ) and the response time is about 1 s. By integrating the sensing and detection elements on the optical fiber, the novel configuration showed advantages of easy fabrication and low cost. Parameters of sensitivity, response time, repeatability, humidity effect and temperature effect were discussed in detail. The proposed sensor showed potential for practical in-breath O(2) analysis application due to its advantages of easy fabrication, low cost, fast response, excellent hydrophobicity, negligible temperature interference and suitable sensitivity.

  12. The energy sensor AMPK regulates Hedgehog signaling in human cells through a unique Gli1 metabolic checkpoint

    PubMed Central

    Di Magno, Laura; Basile, Alessio; Coni, Sonia; Manni, Simona; Sdruscia, Giulia; D'Amico, Davide; Antonucci, Laura; Infante, Paola; De Smaele, Enrico; Cucchi, Danilo; Ferretti, Elisabetta; Di Marcotullio, Lucia; Screpanti, Isabella; Canettieri, Gianluca

    2016-01-01

    Hedgehog signaling controls proliferation of cerebellar granule cell precursors (GCPs) and its aberrant activation is a leading cause of Medulloblastoma, the most frequent pediatric brain tumor. We show here that the energy sensor AMPK inhibits Hh signaling by phosphorylating a single residue of human Gli1 that is not conserved in other species. Studies with selective agonists and genetic deletion have revealed that AMPK activation inhibits canonical Hh signaling in human, but not in mouse cells. Indeed we show that AMPK phosphorylates Gli1 at the unique residue Ser408, which is conserved only in primates but not in other species. Once phosphorylated, Gli1 is targeted for proteasomal degradation. Notably, we show that selective AMPK activation inhibits Gli1-driven proliferation and that this effect is linked to Ser408 phosphorylation, which represents a key metabolic checkpoint for Hh signaling. Collectively, this data unveil a novel mechanism of inhibition of Gli1 function, which is exclusive for human cells and may be exploited for the treatment of Medulloblastoma or other Gli1 driven tumors. PMID:26843621

  13. A novel ligand of calcitonin receptor reveals a potential new sensor that modulates programmed cell death

    PubMed Central

    Furness, SGB; Hare, DL; Kourakis, A; Turnley, AM; Wookey, PJ

    2016-01-01

    We have discovered that the accumulation of an anti-calcitonin receptor (anti-CTR) antibody conjugated to a fluorophore (mAb2C4:AF568) provides a robust signal for cells undergoing apoptotic programmed cell death (PCD). PCD is an absolute requirement for normal development of metazoan organisms. PCD is a hallmark of common diseases such as cardiovascular disease and tissue rejection in graft versus host pathologies, and chemotherapeutics work by increasing PCD. This robust signal or high fluorescent events were verified by confocal microscopy and flow cytometry in several cell lines and a primary culture in which PCD had been induced. In Jurkat cells, GBM-L2 and MG63 cells, the percentage undergoing PCD that were positive for both mAb2C4:AF568 and annexin V ranged between 70 and >90%. In MG63 cells induced for the preapoptotic cell stress response (PACSR), the normal expression of α-tubulin, a key structural component of the cytoskeleton, and accumulation of mAb2C4:AF568 were mutually exclusive. Our data support a model in which CTR is upregulated during PACSR and recycles to the plasma membrane with apoptosis. In cells committed to apoptosis (α-tubulin negative), there is accumulation of the CTR-ligand mAb2C4:AF568 generating a high fluorescent event. The reagent mAb2C4:AF568 effectively identifies a novel event linked to apoptosis. PMID:27777788

  14. Invariant natural killer T cells as sensors and managers of inflammation.

    PubMed

    Van Kaer, Luc; Parekh, Vrajesh V; Wu, Lan

    2013-02-01

    Invariant natural killer T (iNKT) cells are a subset of innate-like lymphocytes that recognize glycolipid antigens bound by the major histocompatibility complex (MHC)-class-I-related protein CD1d. iNKT cells are activated early during a variety of infections and inflammatory diseases and contribute to the subsequent development of adaptive immune responses. Consequently, iNKT cells play a critical role in the development and resolution of inflammatory diseases and represent attractive targets for the development of immunotherapies. Recent studies have provided important insight into the mechanisms by which iNKT cells become activated in response to diverse inflammatory stimuli. These new findings should be instrumental to promote the immunomodulatory properties of iNKT cells for treatment of inflammatory diseases.

  15. Commandeering Channel Voltage Sensors for Secretion, Cell Turgor, and Volume Control.

    PubMed

    Karnik, Rucha; Waghmare, Sakharam; Zhang, Ben; Larson, Emily; Lefoulon, Cécile; Gonzalez, Wendy; Blatt, Michael R

    2017-01-01

    Control of cell volume and osmolarity is central to cellular homeostasis in all eukaryotes. It lies at the heart of the century-old problem of how plants regulate turgor, mineral and water transport. Plants use strongly electrogenic H(+)-ATPases, and the substantial membrane voltages they foster, to drive solute accumulation and generate turgor pressure for cell expansion. Vesicle traffic adds membrane surface and contributes to wall remodelling as the cell grows. Although a balance between vesicle traffic and ion transport is essential for cell turgor and volume control, the mechanisms coordinating these processes have remained obscure. Recent discoveries have now uncovered interactions between conserved subsets of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins that drive the final steps in secretory vesicle traffic and ion channels that mediate in inorganic solute uptake. These findings establish the core of molecular links, previously unanticipated, that coordinate cellular homeostasis and cell expansion.

  16. Yeast Based Sensors

    NASA Astrophysics Data System (ADS)

    Shimomura-Shimizu, Mifumi; Karube, Isao

    Since the first microbial cell sensor was studied by Karube et al. in 1977, many types of yeast based sensors have been developed as analytical tools. Yeasts are known as facultative anaerobes. Facultative anaerobes can survive in both aerobic and anaerobic conditions. The yeast based sensor consisted of a DO electrode and an immobilized omnivorous yeast. In yeast based sensor development, many kinds of yeast have been employed by applying their characteristics to adapt to the analyte. For example, Trichosporon cutaneum was used to estimate organic pollution in industrial wastewater. Yeast based sensors are suitable for online control of biochemical processes and for environmental monitoring. In this review, principles and applications of yeast based sensors are summarized.

  17. Intimal smooth muscle cells are a source but not a sensor of anti-inflammatory CYP450 derived oxylipins

    SciTech Connect

    Thomson, Scott; Edin, Matthew L.; Lih, Fred B.; Yaqoob, Muhammad M.; Hammock, Bruce D.; Gilroy, Derek; Zeldin, Darryl C.

    2015-08-07

    Vascular pathologies are associated with changes in the presence and expression of morphologically distinct vascular smooth muscle cells. In particular, in complex human vascular lesions and models of disease in pigs and rodents, an intimal smooth muscle cell (iSMC) which exhibits a stable epithelioid or rhomboid phenotype in culture is often found to be present in high numbers, and may represent the reemergence of a distinct developmental vascular smooth muscle cell phenotype. The CYP450-oxylipin - soluble epoxide hydrolase (sEH) pathway is currently of great interest in targeting for cardiovascular disease. sEH inhibitors limit the development of hypertension, diabetes, atherosclerosis and aneurysm formation in animal models. We have investigated the expression of CYP450-oxylipin-sEH pathway enzymes and their metabolites in paired intimal (iSMC) and medial (mSMC) cells isolated from rat aorta. iSMC basally released significantly larger amounts of epoxy-oxylipin CYP450 products from eicosapentaenoic acid > docosahexaenoic acid > arachidonic acid > linoleic acid, and expressed higher levels of CYP2C12, CYP2B1, but not CYP2J mRNA compared to mSMC. When stimulated with the pro-inflammatory TLR4 ligand LPS, epoxy-oxylipin production did not change greatly in iSMC. In contrast, LPS induced epoxy-oxylipin products in mSMC and induced CYP2J4. iSMC and mSMC express sEH which metabolizes primary epoxy-oxylipins to their dihydroxy-counterparts. The sEH inhibitors TPPU or AUDA inhibited LPS-induced NFκB activation and iNOS induction in mSMC, but had no effect on NFκB nuclear localization or inducible nitric oxide synthase in iSMC; effects which were recapitulated in part by addition of authentic epoxy-oxylipins. iSMCs are a rich source but not a sensor of anti-inflammatory epoxy-oxylipins. Complex lesions that contain high levels of iSMCs may be more resistant to the protective effects of sEH inhibitors. - Highlights: • We examined oxylipin production in different

  18. Novel localized surface plasmon resonance based optical fiber sensor

    NASA Astrophysics Data System (ADS)

    Muri, Harald Ian D. I.; Hjelme, Dag R.

    2016-03-01

    Over the last decade various optical fiber sensing schemes have been proposed based on local surface plasmon resonance (LSPR). LSPR are interacting with the evanescent field from light propagating in the fiber core or by interacting with the light at the fiber end face. Sensor designs utilizing the fiber end face is strongly preferred from a manufacturing point of view. However, the different techniques available to immobilize metallic nanostructures on the fiber end face for LSPR sensing is limited to essentially a monolayer, either by photolithographic structuring of metal film, thermal nucleation of metal film, or by random immobilization of nanoparticles (NP). In this paper, we report on a novel LSPR based optical fiber sensor architecture. The sensor is prepared by immobilizing gold NP's in a hydrogel droplet polymerized on the fiber end face. This design has several advantages over earlier designs. It dramatically increase the number of NP's available for sensing, it offers precise control over the NP density, and the NPs are position in a true 3D aqueous environment. The sensor design is also compatible with low cost manufacturing. The sensor design can measure volumetric changes in a stimuli-responsive hydrogel or measure binding to receptors on the NP surface. It can also be used as a two-parameter sensor by utilizing both effects. We present results from proof-of-concept experiments demonstrating a pH sensor based on LSPR sensing in a poly(acrylamide-co-acrylic acid) hydrogel embedding gold nanoparticles.

  19. γδ T cells as early sensors of tissue damage and mediators of secondary neurodegeneration

    PubMed Central

    Gelderblom, Mathias; Arunachalam, Priyadharshini; Magnus, Tim

    2014-01-01

    Spontaneous or medically induced reperfusion occurs in up to 70% of patients within 24 h after cerebral ischemia. Reperfusion of ischemic brain tissue can augment the inflammatory response that causes additional injury. Recently, T cells have been shown to be an essential part of the post-ischemic tissue damage, and especially IL-17 secreting T cells have been implicated in the pathogenesis of a variety of inflammatory reactions in the brain. After stroke, it seems that the innate γδ T cells are the main IL-17 producing cells and that the γδ T cell activation constitutes an early and mainly damaging immune response in stroke. Effector mechanism of γδ T cell derived IL-17 in the ischemic brain include the induction of metalloproteinases, proinflammatory cytokines and neutrophil attracting chemokines, leading to a further amplification of the detrimental inflammatory response. In this review, we will give an overview on the concepts of γδ T cells and IL-17 in stroke pathophysiology and on their potential importance for human disease conditions. PMID:25414640

  20. Multichannel lens-free CMOS sensors for real-time monitoring of cell growth.

    PubMed

    Chang, Ko-Tung; Chang, Yu-Jen; Chen, Chia-Ling; Wang, Yao-Nan

    2015-02-01

    A low-cost platform is proposed for the growth and real-time monitoring of biological cells. The main components of the platform include a PMMA cell culture microchip and a multichannel lens-free CMOS (complementary metal-oxide-semiconductor) / LED imaging system. The PMMA microchip comprises a three-layer structure and is fabricated using a low-cost CO2 laser ablation technique. The CMOS / LED monitoring system is controlled using a self-written LabVIEW program. The platform has overall dimensions of just 130 × 104 × 115 mm(3) and can therefore be placed within a commercial incubator. The feasibility of the proposed system is demonstrated using HepG2 cancer cell samples with concentrations of 5000, 10 000, 20 000, and 40 000 cells/mL. In addition, cell cytotoxicity tests are performed using 8, 16, and 32 mM cyclophosphamide. For all of the experiments, the cell growth is observed over a period of 48 h. The cell growth rate is found to vary in the range of 44∼52% under normal conditions and from 17.4∼34.5% under cyclophosphamide-treated conditions. In general, the results confirm the long-term cell growth and real-time monitoring ability of the proposed system. Moreover, the magnification provided by the lens-free CMOS / LED observation system is around 40× that provided by a traditional microscope. Consequently, the proposed system has significant potential for long-term cell proliferation and cytotoxicity evaluation investigations.

  1. Chemical, biochemical, and environmental fiber sensors III; Proceedings of the Meeting, Boston, MA, Sept. 4, 5, 1991

    SciTech Connect

    Lieberman, R.A.

    1992-01-01

    Various papers on chemical, biochemical, and environmental fiber sensors are presented. Individual topics addressed include: fiber optic pressure sensor for combustion monitoring and control, viologen-based fiber optic oxygen sensors, renewable-reagent fiber optic sensor for ocean pCO2, transition metal complexes as indicators for a fiber optic oxygen sensor, fiber optic pH measurements using azo indicators, simple reversible fiber optic chemical sensors using solvatochromic dyes, totally integrated optical measuring sensors, integrated optic biosensor for environmental monitoring, radiation dosimetry using planar waveguide sensors, optical and piezoelectric analysis of polymer films for chemical sensor characterization, source polarization effects in an optical fiber fluorosensor, lens-type refractometer for on-line chemical analysis, fiber optic hydrocarbon sensor system, chemical sensors for environmental monitoring, optical fibers for liquid-crystal sensing and logic devices, suitability of single-mode fluoride fibers for evanescent-wave sensing, integrated modules for fiber optic sensors, optoelectronic sensors based on narrowband A3B5 alloys, fiber Bragg grating chemical sensor.

  2. Real-time determination of telomerase activity in cell extracts using an optical biosensor.

    PubMed

    Schmidt, Peter M; Matthes, Eckart; Scheller, Frieder W; Bienert, Michael; Lehmann, Christine; Ehrlich, Angelika; Bier, Frank F

    2002-10-01

    A biosensoric approach has been developed to determine the activity of telomerase in tumor cell lysates. An optical sensor, the grating coupler, was used to monitor the association and dissociation of unlabeled compounds on the sensor surface in real time, by virtue of an evanescent field. An oligonucleotide was immobilized on the surface of the optical biosensor and linked with two other oligonucleotides by complementary sequences in an overlapping manner. The 3'-end of the last one carried the sequence of the telomeric substrate (TS) primer used for elongation by telomerase in the telomeric repeat amplification protocol (TRAP) assay. This primer sequence was phosphorothioate (PS)-modified, which is known to strongly increase the affinity to the primer binding site of telomerase protein and consequently the velocity of the telomerase reaction. We show that the PS primer binds to the modified biosensor and is elongated effectively by the telomerase from HL-60 cell lysates. A synthesis rate of 1 nucleotide/min was determined. The inhibitory effect of peptide nucleic acid (PNA) was shown by using immobilized TS. The velocity of the telomerase reaction was slowed down and the signal intensity was below the signal-to-noise ratio. Most nucleic acid detection systems use amplification steps such as polymerase chain reaction (PCR) to increase the amount of the probe. Since telomerase is a polymerase itself amplification of DNA by PCR is not required. Furthermore, no purification steps were required since all measurements were performed with crude cell extract.

  3. Energy metabolism and metabolic sensors in stem cells: the metabostem crossroads of aging and cancer.

    PubMed

    Menendez, Javier A; Joven, Jorge

    2014-01-01

    We are as old as our adult stem cells are; therefore, stem cell exhaustion is considered a hallmark of aging. Our tumors are as aggressive as the number of cancer stem cells (CSCs) they bear because CSCs can survive treatments with hormones, radiation, chemotherapy, and molecularly targeted drugs, thus increasing the difficulty of curing cancer. Not surprisingly, interest in stem cell research has never been greater among members of the public, politicians, and scientists. But how can we slow the rate at which our adult stem cells decline over our lifetime, reducing the regenerative potential of tissues, while efficiently eliminating the aberrant, life-threatening activity of "selfish", immortal, and migrating CSCs? Frustrated by the gene-centric limitations of conventional approaches to aging diseases, our group and other groups have begun to appreciate that bioenergetic metabolism, i.e., the production of fuel & building blocks for growth and division, and autophagy/mitophagy, i.e., the quality-control, self-cannibalistic system responsible for "cleaning house" and "recycling the trash", can govern the genetic and epigenetic networks that facilitate stem cell behaviors. Indeed, it is reasonable to suggest the existence of a "metabostem" infrastructure that operates as a shared hallmark of aging and cancer, thus making it physiologically plausible to maintain or even increase the functionality of adult stem cells while reducing the incidence of cancer and extending the lifespan. This "metabostemness" property could lead to the discovery of new drugs that reprogram cell metabotypes to increase the structural and functional integrity of adult stem cells and positively influence their lineage determination, while preventing the development and aberrant function of stem cells in cancer tissues. While it is obvious that the antifungal antibiotic rapamycin, the polyphenol resveratrol, and the biguanide metformin already belong to this new family of metabostemness

  4. SPR-based PCF D-type sensor based on a metamaterial composed of planar metals for refractive index sensing

    NASA Astrophysics Data System (ADS)

    Santos, D. F.; Guerreiro, A.; Baptista, J. M.

    2016-05-01

    This paper presents a numerically investigation of the performance analysis of a conventional photonic crystal fiber (PCF) with a planar metamaterials structure for refractive index sensing, based on surface plasmon resonance (SPR), using the finite element method (FEM). We study the concentration metamaterials conformed by the aluminium oxide (Al2O3) and silver (Ag) and compared its performance with a single metal (Ag), assessing their impacts in the effective refractive index. Furthermore, we also use different types of mechanics to describe the effects of varying the structural parameters sensor on the evanescent field and the sensor performance.

  5. Suitability of invertebrate and vertebrate cells in a portable impedance-based toxicity sensor: temperature mediated impacts on long-term survival.

    PubMed

    Curtis, T M; Collins, A M; Gerlach, B D; Brennan, L M; Widder, M W; van der Schalie, W H; Vo, N T K; Bols, N C

    2013-10-01

    Using ECIS (electric cell-substrate impedance sensing) to monitor the impedance of vertebrate cell monolayers provides a sensitive measure of toxicity for a wide range of chemical toxicants. One major limitation to using a cell-based sensor for chemical toxicant detection in the field is the difficulty in maintaining cell viability over extended periods of time prior to use. This research was performed to identify cell lines suitable for ECIS-based toxicity sensing under field conditions. A variety of invertebrate and vertebrate cell lines were screened for their abilities to be stored for extended periods of time on an enclosed fluidic biochip with minimal maintenance. Three of the ten cell lines screened exhibited favorable portability characteristics on the biochips. Interestingly, all three cell lines were derived from ectothermic vertebrates, and the storage temperature that allowed long-term cell survival on the enclosed fluidic biochips was also at the lower end of reported body temperature for the organism, suggesting that reduced cellular metabolism may be essential for longterm survival on the biochip. Future work with the ectothermic vertebrate cells will characterize their sensitivity to a wide range of chemical toxicants to determine if they are good candidates for use in a field portable toxicity sensor.

  6. A 4,5-quinolimide-based fluorescent sensor for the turn-on detection of Cd(2+) with live-cell imaging.

    PubMed

    Zhang, Yu; Guo, Xiangfeng; Zheng, Mengmeng; Yang, Rui; Yang, Hongming; Jia, Lihua; Yang, Mengmeng

    2017-03-08

    A 4,5-quinolimide derivative, BNA, bearing the amide-DPA receptor, was synthesized as a turn-on fluorescent sensor for Cd(2+). Under physiological conditions, BNA could distinguish Cd(2+) from Zn(2+), showing turn-on fluorescence behaviour and an increased fluorescence lifetime. BNA and Cd(2+) formed a 1 : 1 stoichiometric complex, and the detection limit was measured to be as low as 11 nM. Furthermore, BNA was utilized for fluorescence imaging of Cd(2+) in live cells. To the best of our knowledge, it is the first 4,5-quinolimide-based sensor for the detection of metal ions.

  7. Mast cells as rapid innate sensors of cytomegalovirus by TLR3/TRIF signaling-dependent and -independent mechanisms.

    PubMed

    Becker, Marc; Lemmermann, Niels A W; Ebert, Stefan; Baars, Pamela; Renzaho, Angelique; Podlech, Jürgen; Stassen, Michael; Reddehase, Matthias J

    2015-03-01

    The succinct metaphor, 'the immune system's loaded gun', has been used to describe the role of mast cells (MCs) due to their storage of a wide range of potent pro-inflammatory and antimicrobial mediators in secretory granules that can be released almost instantly on demand to fight invaders. Located at host-environment boundaries and equipped with an arsenal of pattern recognition receptors, MCs are destined to be rapid innate sensors of pathogens penetrating endothelial and epithelial surfaces. Although the importance of MCs in antimicrobial and antiparasitic defense has long been appreciated, their role in raising the alarm against viral infections has been noted only recently. Work on cytomegalovirus (CMV) infection in the murine model has revealed MCs as players in a novel cross-talk axis between innate and adaptive immune surveillance of CMV, in that infection of MCs, which is associated with MC degranulation and release of the chemokine CCL5, enhances the recruitment of protective CD8 T cells to extravascular sites of virus replication, specifically to lung interstitium and alveolar epithelium. Here, we have expanded on these studies by investigating the conditions for MC activation and the consequent degranulation in response to host infection. Surprisingly, the data revealed two temporally and mechanistically distinct waves of MC activation: an almost instant indirect activation that depended on TLR3/TRIF signaling and delayed activation by direct infection of MCs that did not involve TLR3/TRIF signaling. Cell type-specific Cre-recombination that yielded eGFP-expressing reporter virus selectively originating from MCs identified MC as a new in vivo, first-hit target cell of productive murine CMV infection.

  8. Development of materials for solid state electrochemical sensors and fuel cell applications. Final report, September 30, 1995--December 30, 1995

    SciTech Connect

    Bobba, R.; Hormes, J.; Young, V.; Baker, J.A.

    1995-12-31

    The intent of this project was two fold: (1) to develop new ionically conducting materials for solid state gas phase sensors and fuel cells and (2) to train students and create an environment conducive to Solid State Ionics research at Southern University. The authors have investigated the electrode-electrolyte interfacial reactions, defect structure and defect stability in some perovoskite type solid electrolyte materials and the effect of electrocatalyst and electrolyte on direct hydrocarbon and methanol/air fuel cell performance using synchrotron radiation based Extended X-ray Absorption Spectroscopy (EXAFS), surface analytical and Impedance Spectroscopic techniques. They have measured the AC impedance and K edge EXAFS of the entire family of rare earth dopants in Cerium Oxide to understand the effect of dopants on the conductivity and its impact on the structural properties of Cerium Oxide. All of the systems showed an increase in the conductivity over undoped ceria with ceria doped Gd, Sm and Y showing the highest values. The conductivity increased with increasing ionic radius of the dopant cation. The authors have measured the K edge of the EXAFS of these dopants to determine the local structural environment and also to understand the nature of the defect clustering between oxygen vacancies and trivalent ions. The analysis and the data reduction of these complex EXAFS spectra is in progress. Where as in the DOWCs, the authors have attempted to explore the impact of catalyst loadings on the performance of direct oxidation of methanol fuel cells. Their initial measurements on fuel cell performance characteristics and EXAFS are made on commercial membranes Pt/Ru/Nafion 115, 117 and 112.

  9. Evanescent-wave pumped room-temperature single-mode GaAs/AlGaAs core-shell nanowire lasers

    SciTech Connect

    Wei, Wei; Zhang, Xia Ren, Xiaomin; Liu, Yange Wang, Zhi

    2014-06-02

    Evanescent-wave pumped room-temperature single-mode GaAs/AlGaAs core-shell nanowire lasers are proposed and demonstrated. The nanowires are axially excited by evanescent wave outside a microfiber with a diameter about 10 μm via a ns-pulse laser. The lasing emission with a low effective threshold less than 90 nJ is achieved at 868.62 nm along with a linewidth of ∼1.8 nm. Moreover, multiple lasing lines in a wavelength range from 852.56 nm to 882.48 nm are observed. The mechanism of diverse lasing wavelengths is revealed. Furthermore, the proposed GaAs/AlGaAs nanowire laser has advantages such as simple structure, easy to operate, and controllable lasing wavelength, tending to be practical in optical communications and integrated photonic circuits.

  10. Nano-islands integrated evanescence-based lab-on-a-chip on silica-on-silicon and polydimethylsiloxane hybrid platform for detection of recombinant growth hormone

    PubMed Central

    Ozhikandathil, J.; Packirisamy, M.

    2012-01-01

    Integration of nano-materials in optical microfluidic devices facilitates the realization of miniaturized analytical systems with enhanced sensing abilities for biological and chemical substances. In this work, a novel method of integration of gold nano-islands in a silica-on-silicon-polydimethylsiloxane microfluidic device is reported. The device works based on the nano-enhanced evanescence technique achieved by interacting the evanescent tail of propagating wave with the gold nano-islands integrated on the core of the waveguide resulting in the modification of the propagating UV-visible spectrum. The biosensing ability of the device is investigated by finite-difference time-domain simulation with a simplified model of the device. The performance of the proposed device is demonstrated for the detection of recombinant growth hormone based on antibody-antigen interaction. PMID:24106526

  11. Superluminal advanced transmission of X waves undergoing frustrated total internal reflection: the evanescent fields and the Goos-Hänchen effect.

    PubMed

    Shaarawi, Amr M; Tawfik, Bassem H; Besieris, Ioannis M

    2002-10-01

    A study of X waves undergoing frustrated total internal reflection at a planar slab is provided. This is achieved by choosing the spectral plane wave components of the incident X wave to fall on the upper interface at angles greater than the critical angle. Thus, evanescent fields are generated in the slab and the peak of the field tunneling through the slab appears to be transmitted at a superluminal speed. Furthermore, it is shown that for deep barrier penetration, the peak of the transmitted field emerges from the rear interface of the slab before the incident peak reaches the front interface. To understand this advanced transmission of the peak of the pulse, a detailed study of the behavior of the evanescent fields in the barrier region is undertaken. The difference in tunneling behavior between deep and shallow barrier penetrations is shown to be influenced by the sense of the Goos-Hänchen shift.

  12. A non-invasive fluorescence-based oxygen sensor and platform for studying cell responses to metabolic agents in real-time

    NASA Astrophysics Data System (ADS)

    Buchapudi, Koutilya Reddy

    A fluorescence-based sensor in a transverse flow/stop measurement platform has been developed to determine real-time changes in oxygen consumption rates for cell metabolic studies. The oxygen sensitive fluorophore platinum octaethylporphyrin was embedded in a cellulose acetate matrix and affixed to a fiber optic bundle, which provided for transmission of the excitation and emission wavelengths of the film. The fiber optic bundle was sealed in a sensor head that can be used in standard 24-well plates common to research labs. The utility of the sensor and sensing platform were determined by measuring the changes in oxygen consumption rates of Candida albicans during 90/30 s flow/stop cycles. Exposure of these cells to metabolic antagonists and an enhancer showed the expected decrease and increase in oxygen consumption rates in real time. The applicability of the platform to biological studies is illustrated by determination of synergistic activities between antifungal drugs and fluoride exposure in Candida albicans. The robustness of the fluorophore film is demonstrated by perfusion with different media and analyte conditions in the absence of cells. For stop cycle time intervals less than 1 minute the sensor exhibited a rapid and fairly linear change in fluorescence intensity to changing oxygen concentrations in the measurement chamber. Flow cycle fluorescence intensities were used as a baseline correction for treating the stop cycle fluorescence peaks.

  13. Optical Electronic Bragg Reflection Sensor System with Hydrodynamic Flow Applications

    NASA Technical Reports Server (NTRS)

    Lyons, D. R.

    2003-01-01

    This project, as described in the following report, involved design and fabrication of fiber optic sensors for the detection and measurement of dynamic fluid density variations. These devices are created using UV (ultraviolet) ablation and generally modified transverse holographic fiber grating techniques. The resulting phase gratings created on or immediately underneath the flat portion of D-shaped optical waveguides are characterized as evanescent field sensing devices. The primary applications include the sensor portion of a real-time localized or distributed measurement system for hydrodynamic flow, fluid density measurements, and phase change phenomena. Several design modifications were implemented in an attempt to accomplish the tasks specified in our original proposal. In addition, we have established key collaborative relationships with numerous people and institutions.

  14. Preliminary Development of a Fiber Optic Sensor for Measuring Bilirubin

    PubMed Central

    Babin, Steven M; Sova, Raymond M

    2014-01-01

    Preliminary development of a fiber optic bilirubin sensor is described, where an unclad sensing portion is used to provide evanescent wave interaction of the transmitted light with the chemical environment. By using a wavelength corresponding to a bilirubin absorption peak, the Beer–Lambert Law can be used to relate the concentration of bilirubin surrounding the sensing portion to the amount of absorbed light. Initial testing in vitro suggests that the sensor response is consistent with the results of bulk absorption measurements as well as the Beer–Lambert Law. In addition, it is found that conjugated and unconjugated bilirubin have different peak absorption wavelengths, so that two optical frequencies may potentially be used to measure both types of bilirubin. Future development of this device could provide a means of real-time, point-of-care monitoring of intravenous bilirubin in critical care neonates with hyperbilirubinemia. PMID:25057239

  15. A sensitive pressure sensor for diamond anvil cell experiments up to 2 GPa: FluoSpheres®

    NASA Astrophysics Data System (ADS)

    Picard, Aude; Oger, Phil M.; Daniel, Isabelle; Cardon, Hervé; Montagnac, Gilles; Chervin, Jean-Claude

    2006-08-01

    We present an optical pressure sensor suitable for experiments in diamond anvil cell in the 0.1MPa-2GPa pressure range, for temperatures between ambient and 323K. It is based on the pressure-dependent fluorescence spectrum of FluoSpheres®, which are commercially available fluorescent microspheres commonly used to measure blood flow in experimental biology. The fluorescence of microspheres is excited by the 514.5nm line of an Ar+ laser, and the resulting spectrum displays three very intense broad bands at 534, 558, and 598nm, respectively. The reference wavelength and pressure gauge is that of the first inflection point of the spectrum, located at 525.6±0.2nm at ambient pressure. It is characterized by an instantaneous and large linear pressure shift of 9.93(±0.08)nm/GPa. The fluorescence of the FluoSpheres® has been investigated as a function of pressure (0.1-4GPa), temperature (295-343K), pH (3-12), salinity, and pressure transmitting medium. These measurements show that, for pressures comprised between 0.1MPa and 2GPa, at temperatures not exceeding 323K, at any pH, in aqueous pressure transmitting media, pressure can be calculated from the wavelength shift of two to three beads, according to the relation P =0.100 (±0.001) Δλi(P ) with Δλi(P )=λi(P)-λi(0) and λi(P) as the wavelength of the first inflection point of the spectrum at the pressure P. This pressure sensor is approximately thirty times more sensitive than the ruby scale and responds instantaneously to pressure variations.

  16. A sensitive pressure sensor for diamond anvil cell experiments up to 2 GPa: FluoSpheres[reg

    SciTech Connect

    Picard, Aude; Oger, Phil M.; Daniel, Isabelle; Cardon, Herve; Montagnac, Gilles; Chervin, Jean-Claude

    2006-08-01

    We present an optical pressure sensor suitable for experiments in diamond anvil cell in the 0.1 MPa-2 GPa pressure range, for temperatures between ambient and 323 K. It is based on the pressure-dependent fluorescence spectrum of FluoSpheres[reg], which are commercially available fluorescent microspheres commonly used to measure blood flow in experimental biology. The fluorescence of microspheres is excited by the 514.5 nm line of an Ar{sup +} laser, and the resulting spectrum displays three very intense broad bands at 534, 558, and 598 nm, respectively. The reference wavelength and pressure gauge is that of the first inflection point of the spectrum, located at 525.6{+-}0.2 nm at ambient pressure. It is characterized by an instantaneous and large linear pressure shift of 9.93({+-}0.08) nm/GPa. The fluorescence of the FluoSpheres[reg] has been investigated as a function of pressure (0.1-4 GPa), temperature (295-343 K), pH (3-12), salinity, and pressure transmitting medium. These measurements show that, for pressures comprised between 0.1 MPa and 2 GPa, at temperatures not exceeding 323 K, at any pH, in aqueous pressure transmitting media, pressure can be calculated from the wavelength shift of two to three beads, according to the relation P=0.100 ({+-}0.001) {delta}{lambda}{sub i}(P) with {delta}{lambda}{sub i}(P)={lambda}{sub i}(P)-{lambda}{sub i}(0) and {lambda}{sub i}(P) as the wavelength of the first inflection point of the spectrum at the pressure P. This pressure sensor is approximately thirty times more sensitive than the ruby scale and responds instantaneously to pressure variations.

  17. Submicrometer fiber-optic chemical sensors: Measuring pH inside single cells. Progress report, October 1990--August 1993

    SciTech Connect

    Kopelman, R.

    1993-12-01

    Starting from scratch, we went in two and a half years to 0.04 micron optical microscopy resolution. We have demonstrated the application of near-field scanning optical microscopy to DNA samples and opened the new fields of near-field scanning spectroscopy and submicron opto- chemical sensors. All of these developments have been important steps towards in-situ DNA imaging and characterization on the nanoscale. Our first goal was to make NSOM (near-field scanning optical microscopy) a working enterprise, capable of