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Sample records for crystal optical biosensor

  1. Optical modeling of liquid crystal biosensors

    NASA Astrophysics Data System (ADS)

    Hwang, Dae Kun; Rey, Alejandro D.

    2006-11-01

    Optical simulations of a liquid crystal biosensor device are performed using an integrated optical/textural model based on the equations of nematodynamics and two optical methods: the Berreman optical matrix method [J. Opt. Soc. Am. 62, 502 (1972)] and the discretization of the Maxwell equations based on the finite difference time domain (FDTD) method. Testing the two optical methods with liquid crystal films of different degrees of orientational heterogeneities demonstrates that only the FDTD method is suitable to model this device. Basic substrate-induced texturing process due to protein adsorption gives rise to an orientation correlation function that is nearly linear with the transmitted light intensity, providing a basis to calibrate the device. The sensitivity of transmitted light to film thickness, protein surface coverage, and wavelength is established. A crossover incident light wavelength close to λco≈500nm is found, such that when λ >λco thinner films are more sensitive to the amount of protein surface coverage, while for λ <λco the reverse holds. In addition it is found that for all wavelengths the sensitivity increases with the amount of protein coverage. The integrated device model based on FDTD optical simulations in conjunction with the Landau-de Gennes nematodynamics model provides a rational basis for further progress in liquid crystal biosensor devices.

  2. Optical detection of sepsis markers using liquid crystal based biosensors

    NASA Astrophysics Data System (ADS)

    McCamley, Maureen K.; Artenstein, Andrew W.; Opal, Steven M.; Crawford, Gregory P.

    2007-02-01

    A liquid crystal based biosensor for the detection and diagnosis of sepsis is currently in development. Sepsis, a major clinical syndrome with a significant public health burden in the US due to a large elderly population, is the systemic response of the body to a localized infection and is defined as the combination of pathologic infection and physiological changes. Bacterial infections are responsible for 90% of cases of sepsis in the US. Currently there is no bedside diagnostic available to positively identify sepsis. The basic detection scheme employed in a liquid crystal biosensor contains attributes that would find value in a clinical setting, especially for the early detection of sepsis. Utilizing the unique properties of liquid crystals, such as birefringence, a bedside diagnostic is in development which will optically report the presence of biomolecules. In a septic patient, an endotoxin known as lipopolysaccharide (LPS) is released from the outer membrane of Gram-negative bacteria and can be found in the blood stream. It is hypothesized that this long chained molecule will cause local disruptions to the open surface of a sensor containing aligned liquid crystal. The bulk liquid crystal ampli.es these local changes at the surface due to the presence of the sepsis marker, providing an optical readout through polarizing microscopy images. Liquid crystal sensors consisting of both square and circular grids, 100-200 μm in size, have been fabricated and filled with a common liquid crystal material, 5CB. Homeotropic alignment was confirmed using polarizing microscopy. The grids were then contacted with either saline only (control), or saline with varying concentrations of LPS. Changes in the con.guration of the nematic director of the liquid crystal were observed through the range of concentrations tested (5mg/mL - 1pg/mL) which have been confirmed by a consulting physician as clinically relevant levels.

  3. Photonic crystal biosensor based on optical surface waves.

    PubMed

    Konopsky, Valery N; Karakouz, Tanya; Alieva, Elena V; Vicario, Chiara; Sekatskii, Sergey K; Dietler, Giovanni

    2013-01-01

    A label-free biosensor device based on registration of photonic crystal surface waves is described. Angular interrogation of the optical surface wave resonance is used to detect changes in the thickness of an adsorbed layer, while an additional simultaneous detection of the critical angle of total internal reflection provides independent data of the liquid refractive index. The abilities of the device are demonstrated by measuring of biotin molecule binding to a streptavidin monolayer, and by measuring association and dissociation kinetics of immunoglobulin G proteins. Additionally, deposition of PSS / PAH polyelectrolytes is recorded in situ resulting calculation of PSS and PAH monolayer thicknesses separately. PMID:23429517

  4. Optical biosensors

    PubMed Central

    Damborský, Pavel; Švitel, Juraj

    2016-01-01

    Optical biosensors represent the most common type of biosensor. Here we provide a brief classification, a description of underlying principles of operation and their bioanalytical applications. The main focus is placed on the most widely used optical biosensors which are surface plasmon resonance (SPR)-based biosensors including SPR imaging and localized SPR. In addition, other optical biosensor systems are described, such as evanescent wave fluorescence and bioluminescent optical fibre biosensors, as well as interferometric, ellipsometric and reflectometric interference spectroscopy and surface-enhanced Raman scattering biosensors. The optical biosensors discussed here allow the sensitive and selective detection of a wide range of analytes including viruses, toxins, drugs, antibodies, tumour biomarkers and tumour cells. PMID:27365039

  5. Optical biosensors.

    PubMed

    Damborský, Pavel; Švitel, Juraj; Katrlík, Jaroslav

    2016-06-30

    Optical biosensors represent the most common type of biosensor. Here we provide a brief classification, a description of underlying principles of operation and their bioanalytical applications. The main focus is placed on the most widely used optical biosensors which are surface plasmon resonance (SPR)-based biosensors including SPR imaging and localized SPR. In addition, other optical biosensor systems are described, such as evanescent wave fluorescence and bioluminescent optical fibre biosensors, as well as interferometric, ellipsometric and reflectometric interference spectroscopy and surface-enhanced Raman scattering biosensors. The optical biosensors discussed here allow the sensitive and selective detection of a wide range of analytes including viruses, toxins, drugs, antibodies, tumour biomarkers and tumour cells. PMID:27365039

  6. Slotted photonic crystal biosensors

    NASA Astrophysics Data System (ADS)

    Scullion, Mark Gerard

    Optical biosensors are increasingly being considered for lab-on-a-chip applications due to their benefits such as small size, biocompatibility, passive behaviour and lack of the need for fluorescent labels. The light guiding mechanisms used by many of them result in poor overlap of the optical field with the target molecules, reducing the maximum sensitivity achievable. This thesis presents a new platform for optical biosensors, namely slotted photonic crystals, which engender higher sensitivities due to their ability to confine, spatially and temporally, the peak of optical mode within the analyte itself. Loss measurements showed values comparable to standard photonic crystals, confirming their ability to be used in real devices. A novel resonant coupler was designed, simulated, and experimentally tested, and was found to perform better than other solutions within the literature. Combining with cavities, microfluidics and biological functionalization allowed proof-of-principle demonstrations of protein binding to be carried out. High sensitivities were observed in smaller structures than most competing devices in the literature. Initial tests with cellular material for real applications was also performed, and shown to be of promise. In addition, groundwork to make an integrated device that includes the spectrometer function was also carried out showing that slotted photonic crystals themselves can be used for on-chip wavelength specific filtering and spectroscopy, whilst gas-free microvalves for automation were also developed. This body of work presents slotted photonic crystals as a realistic platform for complete on-chip biosensing; addressing key design, performance and application issues, whilst also opening up exciting new ideas for future study.

  7. Nano-optic label-free biosensors based on photonic crystal platform with negative refraction

    NASA Astrophysics Data System (ADS)

    Aroua, W.; Haxha, S.; AbdelMalek, F.

    2012-04-01

    In this paper, a novel biosensor based on hetero photonic crystal (PC) structures is proposed. The biosensor consists of photonic crystals with negative refraction (PCNR) embedded between two ordinary PC structures. The PCNR is employed in order to produce an image that is as similar as the light source, which is located in the first ordinary PC. Significant enhancement of the image is achieved when a nanocavity is introduced into the PCNR. It is found that the transmission peak shifts when the nanocavity is filled with blood plasma, liquid and dry air. It is shown that by careful selection of the radius of the nanocavity, the sensitivity of the proposed biosensor can be enhanced. The presented PCNR biosensor is investigated by employing the finite-difference time-domain method (FDTD).

  8. Highly-sensitive liquid crystal biosensor based on DNA dendrimers-mediated optical reorientation.

    PubMed

    Tan, Hui; Li, Xia; Liao, Shuzhen; Yu, Ruqin; Wu, Zhaoyang

    2014-12-15

    A novel highly-sensitive liquid crystal (LC) biosensing approach based on target-triggering DNA dendrimers was developed for the detection of p53 mutation gene segment at the LC-aqueous interface. In this study, the mutant-type p53 gene segment was the target to trigger the formation of DNA dendrimers from hairpin DNA probes by hybridization chain reaction, and the latter as a 'signal enhancement element' further induced the LC reorientation from tilted to homeotropic alignment, resulting in a corresponding optical changes of LC biosensors from birefringent to honeycombed textures or dark framework. The distinct optical reorientational appearances can serve as a characteristic signal to distinguish target concentrations ranging from 0.08 nM to 8 nM. Moreover, these optical phenomena suggest that the LC reorientation is related to the electric-dipole coupling between the adsorbed DNA and LC molecules, the conformational constraints of DNA and the internal electric field induction upon hybridization. This label-free LC biosensing strategy can open up a new platform for the sensitive detection of specific DNA sequences and enrich the application scope of an LC biosensing technique. PMID:24984288

  9. Triggered optical biosensor

    DOEpatents

    Song, Xuedong; Swanson, Basil I.

    2001-10-02

    An optical biosensor is provided for the detection of a multivalent target biomolecule, the biosensor including a substrate having a bilayer membrane thereon, a recognition molecule situated at the surface, the recognition molecule capable of binding with the multivalent target biomolecule, the recognition molecule further characterized as including a fluorescence label thereon and as being movable at the surface and a device for measuring a fluorescence change in response to binding between the recognition molecule and the multivalent target biomolecule.

  10. Fiber optic choline biosensor

    NASA Astrophysics Data System (ADS)

    Wang, Hong; Cao, Xiaojian; Jia, Ke; Chai, Xueting; Lu, Hua; Lu, Zuhong

    2001-10-01

    A fiber optic fluorescence biosensor for choline is introduced in this paper. Choline is an important neurotransmitter in mammals. Due to the growing needs for on-site clinical monitoring of the choline, much effect has been devoted to develop choline biosensors. Fiber-optic fluorescence biosensors have many advantages, including miniaturization, flexibility, and lack of electrical contact and interference. The choline fiber-optic biosensor we designed implemented a bifurcated fiber to perform fluorescence measurements. The light of the blue LED is coupled into one end of the fiber as excitation and the emission spectrum from sensing film is monitored by fiber-spectrometer (S2000, Ocean Optics) through the other end of the fiber. The sensing end of the fiber is coated with Nafion film dispersed with choline oxidase and oxygen sensitive luminescent Ru(II) complex (Tris(2,2'-bipyridyl)dichlororuthenium(II), hexahydrate). Choline oxidase catalyzes the oxidation of choline to betaine and hydrogen peroxide while consuming oxygen. The fluorescence intensity of oxygen- sensitive Ru(II) are related to the choline concentration. The response of the fiber-optic sensor in choline solution is represented and discussed. The result indicates a low-cost, high-performance, portable choline biosensor.

  11. Development of optical biosensor based on photonic crystal made of TiO2 using liquid phase deposition

    NASA Astrophysics Data System (ADS)

    Aono, Keigo; Aki, Shoma; Sueyoshi, Kenji; Hisamoto, Hideaki; Endo, Tatsuro

    2016-08-01

    We fabricated a titanium dioxide (TiO2)-based photonic crystal (PhC) using liquid phase deposition (LPD) to develop highly sensitive optical biosensors. The optical characteristics of the PhCs in the visible region were sensitive to the change in the refractive index of the surrounding medium due to an antigen–antibody reaction; thus, applications using the optical biosensor are expected to be highly sensitive. However, a base material with a high refractive index is indispensable for the fabrication of the PhC. Here, TiO2, which has optical transparency in the visible region, was selected as the high refractive index base material. The present LPD method allowed fabrication using low-cost apparatus. Furthermore, the mild conditions of the LPD method led to formation of TiO2-based PhC with fewer crack structures. Finally, the anti-neuron-specific enolase antibody was immobilized onto the TiO2-based PhC surface, and 1–1000 ng/mL of the neuron-specific enolase antigen was successfully detected.

  12. Photonic Crystal Nanolaser Biosensors

    NASA Astrophysics Data System (ADS)

    Kita, Shota; Otsuka, Shota; Hachuda, Shoji; Endo, Tatsuro; Imai, Yasunori; Nishijima, Yoshiaki; Misawa, Hiroaki; Baba, Toshihiko

    High-performance and low-cost sensors are critical devices for high-throughput analyses of bio-samples in medical diagnoses and life sciences. In this paper, we demonstrate photonic crystal nanolaser sensor, which detects the adsorption of biomolecules from the lasing wavelength shift. It is a promising device, which balances a high sensitivity, high resolution, small size, easy integration, simple setup and low cost. In particular with a nanoslot structure, it achieves a super-sensitivity in protein sensing whose detection limit is three orders of magnitude lower than that of standard surface-plasmon-resonance sensors. Our investigations indicate that the nanoslot acts as a protein condenser powered by the optical gradient force, which arises from the strong localization of laser mode in the nanoslot.

  13. Fiber optic-based biosensor

    NASA Technical Reports Server (NTRS)

    Ligler, Frances S.

    1991-01-01

    The NRL fiber optic biosensor is a device which measures the formation of a fluorescent complex at the surface of an optical fiber. Antibodies and DNA binding proteins provide the mechanism for recognizing an analyze and immobilizing a fluorescent complex on the fiber surface. The fiber optic biosensor is fast, sensitive, and permits analysis of hazardous materials remote from the instrumentation. The fiber optic biosensor is described in terms of the device configuration, chemistry for protein immobilization, and assay development. A lab version is being used for assay development and performance characterization while a portable device is under development. Antibodies coated on the fiber are stable for up to two years of storage prior to use. The fiber optic biosensor was used to measure concentration of toxins in the parts per billion (ng/ml) range in under a minute. Immunoassays for small molecules and whole bacteria are under development. Assays using DNA probes as the detection element can also be used with the fiber optic sensor, which is currently being developed to detect biological warfare agents, explosives, pathogens, and toxic materials which pollute the environment.

  14. Optical biosensors for environmental monitoring

    SciTech Connect

    Tamiya, Eiichi

    1996-12-31

    Environmental assessment is important to evaluate the overall health and ecological impact of domestic and industrial wastes. Biosensors are kinds of analytical devices which consist of biomaterials and transducers. Photoluminescence of recombinant E. coli containing lux related genes were used as indicators of environmental pollutions. This paper deals with sensitive and rapid optical sensing systems for monitoring BOD (Biochemical Oxygen Demand), toxic compounds and mutagens.

  15. Modelling a Peroxidase-based Optical Biosensor

    PubMed Central

    Baronas, Romas; Gaidamauskaite, Evelina; Kulys, Juozas

    2007-01-01

    The response of a peroxidase-based optical biosensor was modelled digitally. A mathematical model of the optical biosensor is based on a system of non-linear reaction-diffusion equations. The modelling biosensor comprises two compartments, an enzyme layer and an outer diffusion layer. The digital simulation was carried out using finite difference technique. The influence of the substrate concentration as well as of the thickness of both the enzyme and diffusion layers on the biosensor response was investigated. Calculations showed complex kinetics of the biosensor response, especially at low concentrations of the peroxidase and of the hydrogen peroxide.

  16. Recent Development in Optical Fiber Biosensors

    PubMed Central

    Bosch, María Espinosa; Sánchez, Antonio Jesús Ruiz; Rojas, Fuensanta Sánchez; Ojeda, Catalina Bosch

    2007-01-01

    Remarkable developments can be seen in the field of optical fibre biosensors in the last decade. More sensors for specific analytes have been reported, novel sensing chemistries or transduction principles have been introduced, and applications in various analytical fields have been realised. This review consists of papers mainly reported in the last decade and presents about applications of optical fiber biosensors. Discussions on the trends in optical fiber biosensor applications in real samples are enumerated.

  17. Integrated optical biosensor system (IOBS)

    DOEpatents

    Grace, Karen M.; Sweet, Martin R.; Goeller, Roy M.; Morrison, Leland Jean; Grace, Wynne Kevin; Kolar, Jerome D.

    2007-10-30

    An optical biosensor has a first enclosure with a pathogen recognition surface, including a planar optical waveguide and grating located in the first enclosure. An aperture is in the first enclosure for insertion of sample to be investigated to a position in close proximity to the pathogen recognition surface. A laser in the first enclosure includes means for aligning and means for modulating the laser, the laser having its light output directed toward said grating. Detection means are located in the first enclosure and in optical communication with the pathogen recognition surface for detecting pathogens after interrogation by the laser light and outputting the detection. Electronic means is located in the first enclosure and receives the detection for processing the detection and outputting information on the detection, and an electrical power supply is located in the first enclosure for supplying power to the laser, the detection means and the electronic means.

  18. Survey of the 1998 optical biosensor literature.

    PubMed

    Myszka, D G

    1999-01-01

    The utilization of optical biosensors to study molecular interactions continues to expand. In 1998, 384 articles relating to the use of commercial biosensors were published in 130 different journals. While significant strides in new applications and methodology were made, a majority of the biosensor literature is of rather poor quality. Basic information about experimental conditions is often not presented and many publications fail to display the experimental data, bringing into question the credibility of the results. This review provides suggestions on how to collect, analyze and report biosensor data. PMID:10611648

  19. Renewable Surface Biosensors with Optical Detection

    SciTech Connect

    Bruckner-Lea, Cindy J.; Ackerman, Eric J.; Dockendorff, Brian P.; Holman, David A.; Grate, Jay W.

    2001-04-30

    One major challenge in the development of biosensors is the limited lifetime of a chemically selective surface that includes biomolecules. Renewable surface biosensors address this issue by using fresh aliquots of derivatized microbeads for each analysis. The analyte detection can then occur on the microbeads, or downstream from the microbeads. In this paper, we will describe two types of renewable surface biosensors. The first renewable biosensor system includes on-column optical detection for monitoring the binding of biomolecules onto protein or DNA-derivatized Sepharose beads. The second renewable biosensor system includes detection downstream from the microparticles and is based on the use of derivatized magnetic particles for selective binding. The magnetic particles are fluidically captured and released in a sequential injection system to allow the automation of an Enzyme Linked ImmunoSorbent Assay.

  20. Renewable Surface Biosensors With Optical Detection

    SciTech Connect

    Bruckner-Lea, Cynthia J.; Ackerman, Eric J.; Dockendorff, Brian P.; Holman, David A.; Grate, Jay W.

    2001-12-01

    One major challenge in the development of biosensors is the limited lifetime of a chemically selective surface that includes biomolecules. Renewable surface biosensors address this issue by using fresh aliquots of derivatized microbeads for each analysis. The analyte detection can then occur on the microbeads, or downstream from the microbeads. In this paper, we will describe two types of renewable surface biosensors. The first renewable biosensor system includes on-column optical detection for monitoring the binding of biomolecules onto protein or DNA-derivatized Sepharose beads. The second renewable biosensor system includes detection downstream from the microparticles and is based on the use of derivatized magnetic particles for selective binding. The magnetic particles are fluidically captured and released in a sequential injection system to allow the automation of an Enzyme Linked ImmunoSorbent Assay.

  1. Thin Hydrogel Films for Optical Biosensor Applications

    PubMed Central

    Mateescu, Anca; Wang, Yi; Dostalek, Jakub; Jonas, Ulrich

    2012-01-01

    Hydrogel materials consisting of water-swollen polymer networks exhibit a large number of specific properties highly attractive for a variety of optical biosensor applications. This properties profile embraces the aqueous swelling medium as the basis of biocompatibility, non-fouling behavior, and being not cell toxic, while providing high optical quality and transparency. The present review focuses on some of the most interesting aspects of surface-attached hydrogel films as active binding matrices in optical biosensors based on surface plasmon resonance and optical waveguide mode spectroscopy. In particular, the chemical nature, specific properties, and applications of such hydrogel surface architectures for highly sensitive affinity biosensors based on evanescent wave optics are discussed. The specific class of responsive hydrogel systems, which can change their physical state in response to externally applied stimuli, have found large interest as sophisticated materials that provide a complex behavior to hydrogel-based sensing devices. PMID:24957962

  2. Graphene-Based Optical Biosensors and Imaging

    SciTech Connect

    Tang, Zhiwen; He, Shijiang; Pei, Hao; Du, Dan; Fan, Chunhai; Lin, Yuehe

    2014-01-13

    This chapter focuses on the design, fabrication and application of graphene based optical nanobiosensors. The emerging graphene based optical nanobiosensors demonstrated the promising bioassay and biomedical applications thanking to the unique optical features of graphene. According to the different applications, the graphene can be tailored to form either fluorescent emitter or efficient fluorescence quencher. The exceptional electronic feature of graphene makes it a powerful platform for fabricating the SPR and SERS biosensors. Today the graphene based optical biosensors have been constructed to detect various targets including ions, small biomolecules, DNA/RNA and proteins. This chapter reviews the recent progress in graphene-based optical biosensors and discusses the opportunities and challenges in this field.

  3. FIBER OPTIC BIOSENSOR FOR DNA DAMAGE

    EPA Science Inventory

    This paper describes a fiber optic biosensor for the rapid and sensitive detection of radiation-induced or chemically-induced oxidative DNA damage. The assay is based on the hybridization and temperature-induced dissociation (melting curves) of synthetic oligonucleotides. The...

  4. A liquid-crystal-based DNA biosensor for pathogen detection

    NASA Astrophysics Data System (ADS)

    Khan, Mashooq; Khan, Abdur Rahim; Shin, Jae-Ho; Park, Soo-Young

    2016-03-01

    A liquid-crystal (LC)-filled transmission electron microscopy (TEM) grid cell coated with the cationic surfactant dodecyltrimethylammonium bromide (DTAB), to which a single-stranded deoxyribonucleic acid probe (ssDNAprobe) was adsorbed at the LC/aqueous interface (TEMDTAB/DNA), was applied for the highly specific detection of target DNA molecules. The DTAB-coated E7 (used LC mixture) in the TEM grid (TEMDTAB) exhibited a homeotropic orientation, and changed to a planar orientation upon adsorption of the ssDNAprobe. The TEMDTAB/DNA was then exposed to complementary (target) ssDNA, which resulted in a planar-to-homeotropic configurational change of E7 that could be observed through a polarized optical microscope under crossed polarizers. The optimum adsorption density (2 μM) of ssDNAprobe enabled the detection of ≥0.05 nM complementary ssDNA. This TEMDTAB/DNA biosensor could differentiate complementary ssDNA from mismatched ssDNA as well as double-stranded DNA. It also successfully detected the genomic DNAs of the bacterium Erwinia carotovora and the fungi Rhazictonia solani. Owe to the high specificity, sensitivity, and label-free detection, this biosensor may broaden the applications of LC-based biosensors to pathogen detection.

  5. A liquid-crystal-based DNA biosensor for pathogen detection.

    PubMed

    Khan, Mashooq; Khan, Abdur Rahim; Shin, Jae-Ho; Park, Soo-Young

    2016-01-01

    A liquid-crystal (LC)-filled transmission electron microscopy (TEM) grid cell coated with the cationic surfactant dodecyltrimethylammonium bromide (DTAB), to which a single-stranded deoxyribonucleic acid probe (ssDNAprobe) was adsorbed at the LC/aqueous interface (TEMDTAB/DNA), was applied for the highly specific detection of target DNA molecules. The DTAB-coated E7 (used LC mixture) in the TEM grid (TEMDTAB) exhibited a homeotropic orientation, and changed to a planar orientation upon adsorption of the ssDNAprobe. The TEMDTAB/DNA was then exposed to complementary (target) ssDNA, which resulted in a planar-to-homeotropic configurational change of E7 that could be observed through a polarized optical microscope under crossed polarizers. The optimum adsorption density (2 μM) of ssDNAprobe enabled the detection of ≥0.05 nM complementary ssDNA. This TEMDTAB/DNA biosensor could differentiate complementary ssDNA from mismatched ssDNA as well as double-stranded DNA. It also successfully detected the genomic DNAs of the bacterium Erwinia carotovora and the fungi Rhazictonia solani. Owe to the high specificity, sensitivity, and label-free detection, this biosensor may broaden the applications of LC-based biosensors to pathogen detection. PMID:26940532

  6. A liquid-crystal-based DNA biosensor for pathogen detection

    PubMed Central

    Khan, Mashooq; Khan, Abdur Rahim; Shin, Jae-Ho; Park, Soo-Young

    2016-01-01

    A liquid-crystal (LC)-filled transmission electron microscopy (TEM) grid cell coated with the cationic surfactant dodecyltrimethylammonium bromide (DTAB), to which a single-stranded deoxyribonucleic acid probe (ssDNAprobe) was adsorbed at the LC/aqueous interface (TEMDTAB/DNA), was applied for the highly specific detection of target DNA molecules. The DTAB-coated E7 (used LC mixture) in the TEM grid (TEMDTAB) exhibited a homeotropic orientation, and changed to a planar orientation upon adsorption of the ssDNAprobe. The TEMDTAB/DNA was then exposed to complementary (target) ssDNA, which resulted in a planar-to-homeotropic configurational change of E7 that could be observed through a polarized optical microscope under crossed polarizers. The optimum adsorption density (2 μM) of ssDNAprobe enabled the detection of ≥0.05 nM complementary ssDNA. This TEMDTAB/DNA biosensor could differentiate complementary ssDNA from mismatched ssDNA as well as double-stranded DNA. It also successfully detected the genomic DNAs of the bacterium Erwinia carotovora and the fungi Rhazictonia solani. Owe to the high specificity, sensitivity, and label-free detection, this biosensor may broaden the applications of LC-based biosensors to pathogen detection. PMID:26940532

  7. Fiber optic biosensor using aptamer as receptors

    NASA Astrophysics Data System (ADS)

    Yu, Shuqin; Cai, Xiaokun; Tan, Xianglin; Zhu, Yexiang; Lu, Bin

    2001-09-01

    Reagentless biosensor that can directly transducer molecular recognition to optical signal should potentiate the development of sensor array fora wide variety of analytes. Nucleic acid aptamer can bind ligand tightly and specifically with conformational change of aptamer, and can be used as a receptor in biosensor. We have therefore developed a fiber-optic biosensor by aptamer connected with molecular beacon. Molecular beacons consist of an oligonucleotide sequence containing complementary sequence sections at either end. These two sequence containing segments base pair with each other to form a hairpin shaped loop structure, the fluorophore and quencher were attached at 5 foot- and 3 foot-end of molecular beacon respectively. When thrombin binding to the stem-loop of molecular beacon aptamer, the pseudoknot structure was interrupted, resulting a release of fluorescence from quenching and a increase in fluorescence emission. This novel biosensor system in this project has a large potential and is specific and sensitivity. A similar strategy could be used to study other analytes such as protein and small molecules.

  8. Fiber optic-based regenerable biosensor

    DOEpatents

    Sepaniak, Michael J.; Vo-Dinh, Tuan

    1993-01-01

    A fiber optic-based regenerable biosensor. The biosensor is particularly suitable for use in microscale work in situ. In one embodiment, the biosensor comprises a reaction chamber disposed adjacent the distal end of a waveguide and adapted to receive therein a quantity of a sample containing an analyte. Leading into the chamber is a plurality of capillary conduits suitable for introducing into the chamber antibodies or other reagents suitable for selective interaction with a predetermined analyte. Following such interaction, the contents of the chamber may be subjected to an incident energy signal for developing fluorescence within the chamber that is detectable via the optical fiber and which is representative of the presence, i.e. concentration, of the selected analyte. Regeneration of the biosensor is accomplished by replacement of the reagents and/or the analyte, or a combination of these, at least in part via one or more of the capillary conduits. The capillary conduits extend from their respective terminal ends that are in fluid communication with the chamber, away from the chamber to respective location(s) remote from the chamber thereby permitting in situ location of the chamber and remote manipulation and/or analysis of the activity with the chamber.

  9. Integrated-optical directional coupler biosensor

    NASA Astrophysics Data System (ADS)

    Luff, B. J.; Harris, R. D.; Wilkinson, J. S.; Wilson, R.; Schiffrin, D. J.

    1996-04-01

    We present measurements of biomolecular binding reactions, using a new type of integrated-optical biosensor based on a planar directional coupler structure. The device is fabricated by Ag+ - Na+ ion exchange in glass, and definition of the sensing region is achieved by use of transparent fluoropolymer isolation layers formed by thermal evaporation. The suitability of the sensor for application to the detection of environmental pollutants is considered.

  10. Fiber-Optic Chemical and Biosensors

    NASA Astrophysics Data System (ADS)

    El-Sherif, Mahmoud

    In the past 15 years, the fiber-optic communication industry has literally revolutionized the telecommunication industry by providing higher performance and more reliable telecommunication links. In parallel to these developments, and due to the high volume production of fiber-optic components at reasonable performance and costs, other industries associated with fiber optics have been developed like the sensors industry. As component prices have fallen and quality improvements have been made, the ability of fiber-optic sensors to displace conventional sensors have become a reality. A major category in fiber-optic sensors is the chemical and biosensors. These sensors can provide numerous advantages over conventional sensors. These advantages are higher performance, light weight, small and compact size, immunity to electromagnetic interference, remote sensing, ability to be multiplexed, and ability to be embedded into various structures and materials. The sensor's sensitivity and selectivity are enhanced by using optical transducers capable of precise detection of surround changes.

  11. High-density fiber optic biosensor arrays

    NASA Astrophysics Data System (ADS)

    Epstein, Jason R.; Walt, David R.

    2002-02-01

    Novel approaches are required to coordinate the immense amounts of information derived from diverse genomes. This concept has influenced the expanded role of high-throughput DNA detection and analysis in the biological sciences. A high-density fiber optic DNA biosensor was developed consisting of oligonucleotide-functionalized, 3.1 mm diameter microspheres deposited into the etched wells on the distal face of a 500 micrometers imaging fiber bundle. Imaging fiber bundles containing thousands of optical fibers, each associated with a unique oligonucleotide probe sequence, were the foundation for an optically connected, individually addressable DNA detection platform. Different oligonucleotide-functionalized microspheres were combined in a stock solution, and randomly dispersed into the etched wells. Microsphere positions were registered from optical dyes incorporated onto the microspheres. The distribution process provided an inherent redundancy that increases the signal-to-noise ratio as the square root of the number of sensors examined. The representative amount of each probe-type in the array was dependent on their initial stock solution concentration, and as other sequences of interest arise, new microsphere elements can be added to arrays without altering the existing detection capabilities. The oligonucleotide probe sequences hybridize to fluorescently-labeled, complementary DNA target solutions. Fiber optic DNA microarray research has included DNA-protein interaction profiles, microbial strain differentiation, non-labeled target interrogation with molecular beacons, and single cell-based assays. This biosensor array is proficient in DNA detection linked to specific disease states, single nucleotide polymorphism (SNP's) discrimination, and gene expression analysis. This array platform permits multiple detection formats, provides smaller feature sizes, and enables sensor design flexibility. High-density fiber optic microarray biosensors provide a fast

  12. Slow light engineering for high Q high sensitivity photonic crystal microcavity biosensors in silicon

    PubMed Central

    Chakravarty, Swapnajit; Zou, Yi; Lai, Wei-Cheng; Chen, Ray T.

    2012-01-01

    Current trends in photonic crystal microcavity biosensors in silicon-on-insulator (SOI), that focus on small and smaller sensors have faced a bottleneck trying to balance two contradictory requirements of resonance quality factor and sensitivity. By simultaneous control of the radiation loss and optical mode volumes, we show that both requirements can be satisfied simultaneously. Microcavity sensors are designed in which resonances show highest Q ~9,300 in the bio-ambient phosphate buffered saline (PBS) as well as highest sensitivity among photonic crystal biosensors. We experimentally demonstrated mass sensitivity 8.8 atto-grams with sensitivity per unit area of 0.8 picograms/mm2 Highest sensitivity, irrespective of the dissociation constant Kd, is demonstrated among all existing label-free optical biosensors in silicon at the concentration of 0.1μg/ml. PMID:22748964

  13. Low-cost label-free biosensors using photonic crystals embedded between crossed polarizers.

    PubMed

    Nazirizadeh, Yousef; Bog, Uwe; Sekula, Sylwia; Mappes, Timo; Lemmer, Uli; Gerken, Martina

    2010-08-30

    There is a strong need for low-cost biosensors to enable rapid, on-site analysis of biological, biomedical, or chemical substances. We propose a platform for label-free optical biosensors based on applying the analyte onto a surface-functionalized photonic crystal slab and performing a transmission measurement with two crossed polarization filters. This dark-field approach allows for efficient background suppression as only the photonic crystal guided-mode resonances interacting with the functionalized surface experience significant polarization rotation. We present a compact biosensor demonstrator using a low-cost light emitting diode and a simple photodiode capable of detecting the binding kinetics of a 2.5 nM solution of the protein streptavidin on a biotin-functionalized photonic crystal surface. PMID:20940807

  14. Liquid crystal-based proton sensitive glucose biosensor.

    PubMed

    Khan, Mashooq; Park, Soo-Young

    2014-02-01

    A transmission electron microscopy (TEM) grid filled with 4-cyno-4-pentylbiphenyl (5CB) on the octadecyltrichloro silane-coated glass in an aqueous medium was developed to construct a glucose biosensor by coating poly(acrylicacid-b-4-cynobiphenyl-4-oxyundecylacrylate) (PAA-b-LCP) at the aqueous/5CB interface and immobilizing glucose oxidase (GOx) covalently to the PAA chains. The glucose was detected from a homeotropic to planar orientational transition of 5CB by polarized optical microscopy under crossed polarizers. The maximum immobilization density of the GOx, 1.3 molecules/nm(2) obtained in this TEM grid cell enabled the detection of glucose at concentrations as low as 0.02 mM with a response time of 10 s. This liquid crystal-based glucose sensor provided a linear response of birefringence of the 5CB to glucose concentrations ranging from 0.05 to 2 mM with a Michaelis-Menten constant (Km) of 0.32 mM. This new and sensitive glucose biosensor has the merits of low production cost and easy detection through the naked eye and might be useful for prescreening the glucose level in the human body. PMID:24432733

  15. Non-Invasive Optical Biosensor for Probing Cell Signaling

    PubMed Central

    Fang, Ye

    2007-01-01

    Cell signaling mediated through a cellular target is encoded by spatial and temporal dynamics of downstream signaling networks. The coupling of temporal dynamics with spatial gradients of signaling activities guides cellular responses upon stimulation. Monitoring the integration of cell signaling in real time, if realized, would provide a new dimension for understanding cell biology and physiology. Optical biosensors including resonant waveguide grating (RWG) biosensor manifest a physiologically relevant and integrated cellular response related to dynamic redistribution of cellular matters, thus providing a non-invasive means for cell signaling study. This paper reviews recent progresses in biosensor instrumentation, and theoretical considerations and potential applications of optical biosensors for whole cell sensing.

  16. Fiber optic D dimer biosensor

    DOEpatents

    Glass, R.S.; Grant, S.A.

    1999-08-17

    A fiber optic sensor for D dimer (a fibrinolytic product) can be used in vivo (e.g., in catheter-based procedures) for the diagnosis and treatment of stroke-related conditions in humans. Stroke is the third leading cause of death in the United States. It has been estimated that strokes and stroke-related disorders cost Americans between $15-30 billion annually. Relatively recently, new medical procedures have been developed for the treatment of stroke. These endovascular procedures rely upon the use of microcatheters. These procedures could be facilitated with this sensor for D dimer integrated with a microcatheter for the diagnosis of clot type, and as an indicator of the effectiveness, or end-point of thrombolytic therapy. 4 figs.

  17. Fiber optic D dimer biosensor

    DOEpatents

    Glass, Robert S.; Grant, Sheila A.

    1999-01-01

    A fiber optic sensor for D dimer (a fibrinolytic product) can be used in vivo (e.g., in catheter-based procedures) for the diagnosis and treatment of stroke-related conditions in humans. Stroke is the third leading cause of death in the United States. It has been estimated that strokes and stroke-related disorders cost Americans between $15-30 billion annually. Relatively recently, new medical procedures have been developed for the treatment of stroke. These endovascular procedures rely upon the use of microcatheters. These procedures could be facilitated with this sensor for D dimer integrated with a microcatheter for the diagnosis of clot type, and as an indicator of the effectiveness, or end-point of thrombolytic therapy.

  18. Optical biosensors for cell adhesion.

    PubMed

    Ramsden, Jeremy J; Horvath, Robert

    2009-01-01

    Planar optical waveguides offer an ideal substratum for cells on which to reside. The materials from which the waveguides are made--high refractive index transparent dielectrics--correspond to the coatings of medical implants (e.g., the oxides of niobium, tantalum, and titanium) or the high molecular weight polymers used for culture flasks (e.g., polystyrene). The waveguides can furthermore be modified both chemically and morphologically while retaining their full capability for generating an evanescent optical field that has its greatest strength at the interface between the solid substratum and the liquid phase with which it is invariably in contact (i.e., the culture medium bathing the cells), decaying exponentially perpendicular to the interface at a rate controllable by varying the material parameters of the waveguide. Analysis of the perturbation of the evanescent field by the presence of living cells within it enables their size, number density, shape, refractive index (linked to their constitution) and so forth to be determined, the number of parameters depending on the number of waveguide lightmodes analyzed. No labeling of any kind is necessary, and convenient measurement setups are fully compatible with maintaining the cells in their usual environment. If the temporal evolution of the perturbation is analyzed, even more information can be obtained, such as the amount of material (microexudate) secreted by the cell while residing on the surface. Separation of parallel effects simultaneously contributing to the perturbation of the evanescent field can be accomplished by analysis of coupling peak shape when a grating coupler is used to measure the propagation constants of the waveguide lightmodes. PMID:19635032

  19. Highly sensitive bovine serum albumin biosensor based on liquid crystal

    NASA Astrophysics Data System (ADS)

    Sharma, Vikash; Kumar, Ajay; Ganguly, Prasun; Biradar, A. M.

    2014-01-01

    A highly sensitive liquid crystal (LC) based bovine serum albumin (BSA) protein biosensor is designed. A uniform homeotropic alignment of nematic LC was observed in BSA free substrate which changed into homogeneous in presence of BSA. The change in the LC orientation is found to depend strongly on BSA concentration. This change in the LC alignment is attributed to the modification in the surface conditions which is verified by contact angle measurements. We have detected an ultra low concentration (0.5 μg/ml) of BSA. The present study demonstrates the utilization of LC in the realization of high sensitivity biosensors.

  20. Fabrication of Optical Devices Based on Printable Photonics Technology and Its Application for Biosensor

    NASA Astrophysics Data System (ADS)

    Endo, Tatsuro; Okuda, Norimichi; Yanagida, Yasuko; Tanaka, Satoru; Hatsuzawa, Takeshi

    The specific optical characteristics which can be observed nanostructured optical device have great potentials for applying to several applications such as lifescience, optical communications, and data storage. Application of nanostrcutured optical device to industry, we suggest “printable photonics technology” for fabrication of nanostructured optical device based on nanoimprint lithography (NIL). In this study, using printable photonics technology, fabrication of flexible photonic crystal (PC) and its application for biosensor was performed. Using printable photonics technology-based PC for biosensing application, high sensitive detection of protein adsorption (detection limit: 1 pg/ml) could be detected.

  1. Optical Biosensors: A Revolution Towards Quantum Nanoscale Electronics Device Fabrication

    PubMed Central

    Dey, D.; Goswami, T.

    2011-01-01

    The dimension of biomolecules is of few nanometers, so the biomolecular devices ought to be of that range so a better understanding about the performance of the electronic biomolecular devices can be obtained at nanoscale. Development of optical biomolecular device is a new move towards revolution of nano-bioelectronics. Optical biosensor is one of such nano-biomolecular devices that has a potential to pave a new dimension of research and device fabrication in the field of optical and biomedical fields. This paper is a very small report about optical biosensor and its development and importance in various fields. PMID:22131802

  2. Integrated optical biosensor for detection of multivalent proteins

    SciTech Connect

    Kelly, Dan; Grace, Karen M.; Song, Xuedong; Swanson, Basil I.; Frayer, Daniel; Mendes, Sergio B.; Peyghambarian, Nasser

    1999-12-01

    We have developed a simple, highly sensitive and specific optical waveguide sensor for the detection of multivalent proteins. The optical biosensor is based on optically tagged glycolipid receptors embedded within a fluid phospholipid bilayer membrane formed upon the surface of a planar optical waveguide. Binding of multivalent cholera toxin triggers a fluorescence resonance energy transfer that results in a two-color optical change that is monitored by measurement of emitted luminescence above the waveguide surface. The sensor approach is highly sensitive and specific and requires no additional reagents and washing steps. Demonstration of protein-receptor recognition by use of planar optical waveguides provides a path forward for the development of fieldable miniaturized biosensor arrays. (c) 1999 Optical Society of America.

  3. Last Advances in Silicon-Based Optical Biosensors.

    PubMed

    Fernández Gavela, Adrián; Grajales García, Daniel; Ramirez, Jhonattan C; Lechuga, Laura M

    2016-01-01

    We review the most important achievements published in the last five years in the field of silicon-based optical biosensors. We focus specially on label-free optical biosensors and their implementation into lab-on-a-chip platforms, with an emphasis on developments demonstrating the capability of the devices for real bioanalytical applications. We report on novel transducers and materials, improvements of existing transducers, new and improved biofunctionalization procedures as well as the prospects for near future commercialization of these technologies. PMID:26927105

  4. Last Advances in Silicon-Based Optical Biosensors

    PubMed Central

    Fernández Gavela, Adrián; Grajales García, Daniel; Ramirez, Jhonattan C.; Lechuga, Laura M.

    2016-01-01

    We review the most important achievements published in the last five years in the field of silicon-based optical biosensors. We focus specially on label-free optical biosensors and their implementation into lab-on-a-chip platforms, with an emphasis on developments demonstrating the capability of the devices for real bioanalytical applications. We report on novel transducers and materials, improvements of existing transducers, new and improved biofunctionalization procedures as well as the prospects for near future commercialization of these technologies. PMID:26927105

  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. Fluctuating hydrodynamics of nematics for models of liquid-crystal based biosensors via lattice Boltzmann simulations

    NASA Astrophysics Data System (ADS)

    Guzman, Orlando; Velez, Jose Antonio; Castañeda, David

    2008-03-01

    Experimental biosensors based on liquid crystals (LC) use nematics to detect the presence of specific analytes, via the optical textures exhibited by the LC at long times. Efforts to model the time evolution of these textures have relied on relaxational models, ignoring transport phenomena. In this work we include hydrodynamics into a model for these LC biosensors, using lattice Boltzmann (LB) methods and assess the effect on the lifetime of multidomain structures, characteristic of high concentrations of analyte. We apply Yeoman's et al. LB algorithm, which reproduces the hydrodynamic equations developed by Beris and Edwards for LCs. We also take into account thermal fluctuations, by adding random perturbations to the hydrodynamic modes. Following Adhikari et al., their amplitude is determined by the Fluctuation-Dissipation theorem and we excite both hydrodynamic and the sub-hydrodynamic modes (also called ghost modes). As a result, we analyze the influence of the fluctuations and hydrodynamics on the movement of topological defects.

  7. [Optical surface plasmon resonance biosensors in molecular fishing].

    PubMed

    Ivanov, A S; Medvedev, A E

    2015-01-01

    An optical biosensor employing surface plasmon resonance is a highly efficient instrument applicable for direct real time registration of molecular interactions without additional use of any labels or coupled processes. As an independent approach it is especially effective in analysis of various ligand receptor interactions. SPR-biosensors are used for validation of studies on intermolecular interactions in complex biological systems (affinity profiling of various groups of proteins, etc.). Recently, potential application of the SPR-biosensor for molecular fishing (direct affinity binding of target molecules from complex biological mixtures on the optical biosensor surface followed by their elution for identification by LC-MS/MS) has been demonstrated. Using SPR-biosensors in such studies it is possible to solve the following tasks: (a) SPR-based selection of immobilization conditions required for the most effective affinity separation of a particular biological sample; (b) SPR-based molecular fishing for subsequent protein identification by mass spectrometry; (c) SPR-based validation of the interaction of identified proteins with immobilized ligand. This review considers practical application of the SPR technology in the context of recent studies performed in the Institute of Biomedical Chemistry on molecular fishing of real biological objects. PMID:25978389

  8. Optical properties of metal nanoparticles used in biosensors

    NASA Astrophysics Data System (ADS)

    Prokopyeva, Elena; Kaspar, Pavel; Tománek, Pavel; Grmela, Lubomír.

    2015-01-01

    Metal and semiconductor nanoparticles have excellent optical and electrochemical properties that strongly depend on their size and shape. Local biosensors are advanced devices, whose basic working principle is to analyze spectra of noble metal nanoparticles. Here a model of a local biosensor is described. It takes into account the interaction of the particle with a glass prism and the viewing angle of lens. The results for the layered particle made of a polystyrene latex core with a golden outer shell and for nanorods are presented. The influence of the metal shell thickness, particle diameter and the nanoscale rod form on the location of dissipation spectrum maximum is analyzed.

  9. Biosensors.

    ERIC Educational Resources Information Center

    Rechnitz, Garry A.

    1988-01-01

    Describes theory and principles behind biosensors that incorporate biological components as part of a sensor or probe. Projects major applications in medicine and veterinary medicine, biotechnology, food and agriculture, environmental studies, and the military. Surveys current use of biosensors. (ML)

  10. Survey of the year 2007 commercial optical biosensor literature.

    PubMed

    Rich, Rebecca L; Myszka, David G

    2008-01-01

    In 2007, 1179 papers were published that involved the application of optical biosensors. Reported developments in instrument hardware, assay design, and immobilization chemistry continue to improve the technology's throughput, sensitivity, and utility. Compared to recent years, the widest range of platforms, both traditional format and array-based, were used. However, as in the past, we found a disappointingly low percentage of well-executed experiments and thoughtful data interpretation. We are alarmed by the high frequency of suboptimal data and over-interpreted results in the literature. Fortunately, learning to visually recognize good--and more importantly, bad--data is easy. Using examples from the literature, we outline several features of biosensor responses that indicate experimental artifacts versus actual binding events. Our goal is to have everyone, from benchtop scientists to project managers and manuscript reviewers, become astute judges of biosensor results using nothing more than their eyes. PMID:18951413

  11. Application of Optical Biosensors in Small-Molecule Screening Activities

    PubMed Central

    Geschwindner, Stefan; Carlsson, Johan F.; Knecht, Wolfgang

    2012-01-01

    The last two decades have seen remarkable progress and improvements in optical biosensor systems such that those are currently seen as an important and value-adding component of modern drug screening activities. In particular the introduction of microplate-based biosensor systems holds the promise to match the required throughput without compromising on data quality thus representing a sought-after complement to traditional fluidic systems. This article aims to highlight the application of the two most prominent optical biosensor technologies, namely surface plasmon resonance (SPR) and optical waveguide grating (OWG), in small-molecule screening and will present, review and discuss the advantages and disadvantages of different assay formats on these platforms. A particular focus will be on the specific advantages of the inhibition in solution assay (ISA) format in contrast to traditional direct binding assays (DBA). Furthermore we will discuss different application areas for both fluidic as well as plate-based biosensor systems by considering the individual strength of the platforms. PMID:22666031

  12. Silicon photonic crystal resonators for label free biosensor

    NASA Astrophysics Data System (ADS)

    Sana, Amrita Kumar; Honzawa, Keita; Amemiya, Yoshiteru; Yokoyama, Shin

    2016-04-01

    We report the fabrication and characterization of a two-dimensional (2D) silicon photonic crystal biosensor consisting of waveguides and cavity-type and defect-type resonators for enhancing the interactions between light and biomaterials. Sensitivity was measured using sucrose solution and the sensor showed the highest sensitivity [1570 nm/RIU (refractive index unit)] ever reported. We also investigated cavity size effects on resonance wavelength shift, and we observed that a large cavity exhibits a greater resonance wavelength shift. The fabricated sensor has shown a high Q of ∼105 in water and a device figure of merit of 1.2 × 105, which represent the improvements of the device performance over other photonic-crystal-based sensors.

  13. Detection of Myoglobin with an Open-Cavity-Based Label-Free Photonic Crystal Biosensor

    PubMed Central

    Zhang, Bailin; Tamez-Vela, Juan Manuel; Solis, Steven; Bustamante, Gilbert; Peterson, Ralph; Rahman, Shafiqur; Morales, Andres; Tang, Liang; Ye, Jing Yong

    2013-01-01

    The label-free detection of one of the cardiac biomarkers, myoglobin, using a photonic-crystal-based biosensor in a total-internal-reflection configuration (PC-TIR) is presented in this paper. The PC-TIR sensor possesses a unique open optical microcavity that allows for several key advantages in biomolecular assays. In contrast to a conventional closed microcavity, the open configuration allows easy functionalization of the sensing surface for rapid biomolecular binding assays. Moreover, the properties of PC structures make it easy to be designed and engineered for operating at any optical wavelength. Through fine design of the photonic crystal structure, biochemical modification of the sensor surface, and integration with a microfluidic system, we have demonstrated that the detection sensitivity of the sensor for myoglobin has reached the clinically significant concentration range, enabling potential usage of this biosensor for diagnosis of acute myocardial infarction. The real-time response of the sensor to the myoglobin binding may potentially provide point-of-care monitoring of patients and treatment effects. PMID:27006922

  14. An Optical Biosensor for Bacillus Cereus Spore Detection

    NASA Astrophysics Data System (ADS)

    Li, Chengquan; Tom, Harry W. K.

    2005-03-01

    We demonstrate a new transduction scheme for optical biosensing. Bacillus cereus is a pathogen that may be found in food and dairy products and is able to produce toxins and cause food poisoning. It is related to Bacillus anthracis (anthrax). A CCD array covered with micro-structured glass coverslip is used to detect the optical resonant shift due to the binding of the antigen (bacillus cereus spore) to the antibody (polyclonal antibody). This novel optical biosensor scheme has the potential for detecting 10˜100 bioagents in a single device as well as the potential to test for antigens with multiple antibody tests to avoid ``false positives.''

  15. Biosensors based on GaN nanoring optical cavities

    NASA Astrophysics Data System (ADS)

    Kouno, Tetsuya; Takeshima, Hoshi; Kishino, Katsumi; Sakai, Masaru; Hara, Kazuhiko

    2016-05-01

    Biosensors based on GaN nanoring optical cavities were demonstrated using room-temperature photoluminescence measurements. The outer diameter, height, and thickness of the GaN nanorings were approximately 750–800, 900, and 130–180 nm, respectively. The nanorings functioned as whispering-gallery-mode (WGM)-type optical cavities and exhibited sharp resonant peaks like lasing actions. The evanescent component of the WGM was strongly affected by the refractive index of the ambient environment, the type of liquid, and the sucrose concentration of the analyzed solution, resulting in shifts of the resonant wavelengths. The results indicate that the GaN nanorings can potentially be used in sugar sensors of the biosensors.

  16. Gold nanoparticle based signal enhancement liquid crystal biosensors for DNA hybridization assays.

    PubMed

    Yang, Shengyuan; Liu, Yanmei; Tan, Hui; Wu, Chao; Wu, Zhaoyang; Shen, Guoli; Yu, Ruqin

    2012-03-18

    A novel signal enhanced liquid crystal biosensor based on using AuNPs for highly sensitive DNA detection has been developed. This biosensor not only significantly decreases the detection limit, but also offers a simple detection process and shows a good selectivity to distinguish perfectly matched target DNA from two-base mismatched DNA. PMID:22302154

  17. Optical biosensors for bacteria detection by a peptidomimetic antimicrobial compound.

    PubMed

    Tenenbaum, Elena; Segal, Ester

    2015-11-21

    In this work we present a label-free optical biosensor for rapid bacteria detection using a novel peptide-mimetic compound, as the recognition element. The biosensor design is based on an oxidized porous silicon (PSiO2) nanostructure used as the optical transducer, functionalized with the sequence K-[C12K]7 (referred to as K-7α12), which is a synthetic antimicrobial peptide. This compound is a member of a family of oligomers of acylated lysines (OAKs), mimicking the hydrophobicity and charge of natural antimicrobial peptides. The OAK is tethered to the PSiO2 film and the changes in the reflectivity spectrum are monitored upon exposure to Escherichia coli (E. coli) bacterial suspensions and their lysates. We show that capture of bacterial cell fragments induces predictable changes in the reflectivity spectrum, proportional to E. coli concentrations, thereby enabling rapid, sensitive and reproducible detection of E. coli at concentrations as low as 10(3) cells per mL. While for intact bacterial cells, the K-7α12-tethered PSiO2 shows a poor capturing ability, resulting in an insignificant optical response. The biosensor performance is also studied upon exposure to model Gram positive and negative bacterial lysates, suggesting preferential capture of E. coli cell fragments in the presented scheme. These OAK-based biosensors offer significant advantages in comparison with conventional antibody-based assays, in terms of their simple and cost-effective production, while providing numerous possible sequence combinations for designing new detection schemes. PMID:26456237

  18. Acetylcholinesterase liquid crystal biosensor based on modulated growth of gold nanoparticles for amplified detection of acetylcholine and inhibitor.

    PubMed

    Liao, Shuzhen; Qiao, Yanan; Han, Wenting; Xie, Zhaoxia; Wu, Zhaoyang; Shen, Guoli; Yu, Ruqin

    2012-01-01

    A novel acetylcholinesterase (AChE) liquid crystal (LC) biosensor based on enzymatic growth of gold nanoparticles (Au NPs) has been developed for amplified detection of acetylcholine (ACh) and AChE inhibitor. In this method, AChE mediates the hydrolysis of acetylthiocholine (ATCl) to form thiocholine, and the latter further reduces AuCl(4)(-) to Au NPs without Au nanoseeds. This process, termed biometallization, leads to a great enhancement in the optical signal of the LC biosensor due to the large size of Au NPs, which can greatly disrupt the orientational arrangement of LCs. On the other hand, the hydrolysis of ATCl is inhibited in the presence of ACh or organophosphate pesticides (OPs, a AChE inhibitor), which will decrease the catalytic growth of Au NPs and, as a result, reduce the orientational response of LCs. On the basis of such an inhibition mechanism, the AChE LC biosensor can be used as an effective way to realize the detection of ACh and AChE inhibitors. The results showed that the AChE LC biosensor was highly sensitive to ACh with a detection limit of 15 μmol/L and OPs with a detection limit of 0.3 nmol/L. This study provides a simple and sensitive AChE LC biosensing approach and offers effective signal enhanced strategies for the development of enzyme LC biosensors. PMID:22148672

  19. Photonic Crystal Biosensor with In-Situ Synthesized DNA Probes for Enhanced Sensitivity

    SciTech Connect

    Hu, Shuren; Zhao, Y.; Retterer, Scott T; Kravchenko, Ivan I; Weiss, Sharon

    2013-01-01

    We report on a nearly 8-fold increase in multi-hole defect photonic crystal biosensor response by incorporating in-situ synthesis of DNA probes, as compared to the conventional functionalization method employing pre-synthesized DNA probe immobilization.

  20. Portable multichannel fiber optic biosensor for field detection

    NASA Astrophysics Data System (ADS)

    Golden, Joel P.; Saaski, Elric W.; Shriver-Lake, Lisa C.; Anderson, George P.; Ligler, Frances S.

    1997-04-01

    A compact, portable fiber optic biosensor is developed that enables monitoring of up to four fiber optic probes simultaneously. The sensor employs a novel optical fiber bundle jumper for exciting and collecting fluorescence emission from the evanescent wave fiber optic probes. A single fiber in the center of the bundle couples laser excitation into the sensor probe, while the surrounding fibers collect the returning fluorescent emission light. This design requires no beamsplitter, enabling the detection optics and control circuitry to be reduced to a 4 X 6 in. circuit card. Four of these cards are integrated into a single portable system. Results from detection assays for hazardous biological agents and an environmental pollutant are shown.

  1. Miniature fiber optic surface plasmon resonance biosensors

    NASA Astrophysics Data System (ADS)

    Slavik, Radan; Brynda, Eduard; Homola, Jiri; Ctyroky, Jiri

    1999-01-01

    A novel design of surface plasmon resonance fiber optic sensor is reported which leads to a compact, highly miniaturized sensing element with excellent sensitivity. The sensing device is based on a side-polished single-mode optical fiber with a thin metal overlayer supporting surface plasmon waves. The strength of interaction between a fiber mode and a surface plasmon wave depends strongly on the refractive index near the sensing surface. Therefore, refractive index changes associated with biospecific interaction between antibodies immobilized on the sensor and antigen molecules can be monitored by measuring light intensity variations. Detection of horse radish peroxidase (HRP) of the concentration of 100 ng/ml has been accomplished using the fiber optic sensor with a matrix of monoclonal antibodies against HRP immobilized on the sensor surface.

  2. FIBER-OPTIC BIOSENSOR FOR DIRECT DETERMINATION OF ORGANOPHOSPHATE NERVE AGENTS. (R823663)

    EPA Science Inventory

    A fiber-optic enzyme biosensor for the direct measurement of organophosphate nerve
    agents was developed. The basic element of this biosensor is organophosphorus hydrolase
    immobilized on a nylon membrane and attached to the common end of a bifurcated optical fiber
    bundle....

  3. Handheld imaging photonic crystal biosensor for multiplexed, label-free protein detection

    PubMed Central

    Jahns, Sabrina; Bräu, Marion; Meyer, Björn-Ole; Karrock, Torben; Gutekunst, Sören B.; Blohm, Lars; Selhuber-Unkel, Christine; Buhmann, Raymund; Nazirizadeh, Yousef; Gerken, Martina

    2015-01-01

    We present a handheld biosensor system for the label-free and specific multiplexed detection of several biomarkers employing a spectrometer-free imaging measurement system. A photonic crystal surface functionalized with multiple specific ligands forms the optical transducer. The photonic crystal slab is fabricated on a glass substrate by replicating a periodic grating master stamp with a period of 370 nm into a photoresist via nanoimprint lithography and deposition of a 70-nm titanium dioxide layer. Capture molecules are coupled covalently and drop-wise to the photonic crystal surface. With a simple camera and imaging optics the surface-normal transmission is detected. In the transmission spectrum guided-mode resonances are observed that shift due to protein binding. This shift is observed as an intensity change in the green color channel of the camera. Non-functionalized image sections are used for continuous elimination of background drift. In a first experiment we demonstrate the specific and time-resolved detection of 90.0 nm CD40 ligand antibody, 90.0 nM EGF antibody, and 500 nM streptavidin in parallel on one sensor chip. In a second experiment, aptamers with two different spacer lengths are used as receptor. The binding kinetics with association and dissociation of 250 nM thrombin and regeneration of the sensor surface with acidic tris-HCl-buffer (pH 5.0) is presented for two measurement cycles. PMID:26504624

  4. Optical micro-bubble resonators as promising biosensors

    NASA Astrophysics Data System (ADS)

    Giannetti, A.; Barucci, A.; Berneschi, S.; Cosci, A.; Cosi, F.; Farnesi, D.; Nunzi Conti, G.; Pelli, S.; Soria, S.; Tombelli, S.; Trono, C.; Righini, G. C.; Baldini, F.

    2015-05-01

    Recently, optical micro-bubble resonators (OMBRs) have gained an increasing interest in many fields of photonics thanks to their particular properties. These hollow microstructures can be suitable for the realization of label - free optical biosensors by combining the whispering gallery mode (WGM) resonator properties with the intrinsic capability of integrated microfluidics. In fact, the WGMs are morphology-dependent modes: any change on the OMBR inner surface (due to chemical and/or biochemical binding) causes a shift of the resonance position and reduces the Q factor value of the cavity. By measuring this shift, it is possible to obtain information on the concentration of the analyte to be detected. A crucial step for the development of an OMBR-based biosensor is constituted by the functionalization of its inner surface. In this work we report on the development of a physical and chemical process able to guarantee a good homogeneity of the deposed bio-layer and, contemporary, to preserve a high quality factor Q of the cavity. The OMBR capability of working as bioassay was proved by different optical techniques, such as the real time measurement of the resonance broadening after each functionalization step and fluorescence microscopy.

  5. Integrated optical biosensor for rapid detection of bacteria

    NASA Astrophysics Data System (ADS)

    Mathesz, Anna; Valkai, Sándor; Újvárosy, Attila; Aekbote, Badri; Sipos, Orsolya; Stercz, Balázs; Kocsis, Béla; Szabó, Dóra; Dér, András

    2016-02-01

    In medical diagnostics, rapid detection of pathogenic bacteria from body fluids is one of the basic issues. Most state-of-the-art methods require optical labeling, increasing the complexity, duration and cost of the analysis. Therefore, there is a strong need for developing selective sensory devices based on label-free techniques, in order to increase the speed, and reduce the cost of detection. In a recent paper, we have shown that an integrated optical Mach-Zehnder interferometer, a highly sensitive all-optical device made of a cheap photopolymer, can be used as a powerful lab-on-a-chip tool for specific, labelfree detection of proteins. By proper modifications of this technique, our interferometric biosensor was combined with a microfluidic system allowing the rapid and specific detection of bacteria from solutions, having the surface of the sensor functionalized by bacterium-specific antibodies. The experiments proved that the biosensor was able to detect Escherichia coli bacteria at concentrations of 106 cfu/ml within a few minutes, that makes our device an appropriate tool for fast, label-free detection of bacteria from body fluids such as urine or sputum. On the other hand, possible applications of the device may not be restricted to medical microbiology, since bacterial identification is an important task in microbial forensics, criminal investigations, bio-terrorism threats and in environmental studies, as well.

  6. Fiber-optic evanescent wave biosensor of catecholamine neurotransmitter

    NASA Astrophysics Data System (ADS)

    Zhu, Yexiang; Ran, Yong; Xu, Shunqing

    2001-09-01

    Using quartz fiber-immobilized laccase, detection of catecholamine neurotransmitter is described in this work. Laccase is immobilized on the fiber-optic by means of 3- aminopropyltriethoxysilane/glutaraldehyde method. The oxidation products of adrenalin catalyzed by laccade would absorb the fiber-optic evanescent wave according to the products' concentration. The optimal detection range of this fiber-optic biosensor is between 50-250ng/ml. The minimum detection limit is 10ng/ml. The analysis can provide results in only two minutes to detect one sample. Finally, the specificity of the biosensor is high. The special interference of other substrates of laccase such as o- phyenylenediamine (OPD) and benzenediol can be removed by controlling the pH of the reaction buffer. When the OPD concentration is 100ng/ml, the relative error is only 6.3 percent. On the other hand, the non-special interference is removed by employing double-channel differential method.

  7. Optical biosensor based on silicon nanowire ridge waveguide

    NASA Astrophysics Data System (ADS)

    Gamal, Rania; Ismail, Yehia; Swillam, Mohamed A.

    2015-02-01

    Optical biosensors present themselves as an attractive solution for integration with the ever-trending lab-on-a-chip devices. This is due to their small size, CMOS compatibility, and invariance to electromagnetic interference. Despite their many benefits, typical optical biosensors rely on evanescent field detection, where only a small portion of the light interacts with the analyte. We propose to use a silicon nanowire ridge waveguide (SNRW) for optical biosensing. This structure is comprised of an array of silicon nanowires, with the envelope of a ridge, on an insulator substrate. The SNRW maximizes the overlap between the analyte and the incident light wave by introducing voids to the otherwise bulk structure, and strengthens the contribution of the material under test to the overall modal effective index will greatly augment the sensitivity. Additionally, the SNRW provides a fabrication convenience as it covers the entire substrate, ensuring that the etching process would not damage the substrate. FDTD simulations were conducted and showed that the percentage change in the effective index due to a 1% change in the surrounding environment was more than 170 times the amount of change perceived in an evanescent detection based bulk silicon ridge waveguide.

  8. Integrated optical biosensor for rapid detection of bacteria

    NASA Astrophysics Data System (ADS)

    Mathesz, Anna; Valkai, Sándor; Újvárosy, Attila; Aekbote, Badri; Sipos, Orsolya; Stercz, Balázs; Kocsis, Béla; Szabó, Dóra; Dér, András

    2015-12-01

    In medical diagnostics, rapid detection of pathogenic bacteria from body fluids is one of the basic issues. Most state-of-the-art methods require optical labeling, increasing the complexity, duration and cost of the analysis. Therefore, there is a strong need for developing selective sensory devices based on label-free techniques, in order to increase the speed, and reduce the cost of detection. In a recent paper, we have shown that an integrated optical Mach-Zehnder interferometer, a highly sensitive all-optical device made of a cheap photopolymer, can be used as a powerful lab-on-a-chip tool for specific, labelfree detection of proteins. By proper modifications of this technique, our interferometric biosensor was combined with a microfluidic system allowing the rapid and specific detection of bacteria from solutions, having the surface of the sensor functionalized by bacterium-specific antibodies. The experiments proved that the biosensor was able to detect Escherichia coli bacteria at concentrations of 106 cfu/ml within a few minutes, that makes our device an appropriate tool for fast, label-free detection of bacteria from body fluids such as urine or sputum. On the other hand, possible applications of the device may not be restricted to medical microbiology, since bacterial identification is an important task in microbial forensics, criminal investigations, bio-terrorism threats and in environmental studies, as well.

  9. Self assembled monolayer based liquid crystal biosensor for free cholesterol detection

    SciTech Connect

    Tyagi, Mukta; Agrawal, V. V.; Chandran, Achu; Joshi, Tilak; Prakash, Jai; Biradar, A. M.

    2014-04-14

    A unique cholesterol oxidase (ChOx) liquid crystal (LC) biosensor, based on the disruption of orientation in LCs, is developed for cholesterol detection. A self-assembled monolayer (SAM) of Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP) and (3-Aminopropyl)trimethoxy-silane (APTMS) is prepared on a glass plate by adsorption. The enzyme (ChOx) is immobilized on SAM surface for 12 h before utilizing the film for biosensing purpose. LC based biosensing study is conducted on SAM/ChOx/LC (5CB) cells for cholesterol concentrations ranging from 10 mg/dl to 250 mg/dl. The sensing mechanism has been verified through polarizing optical microscopy, scanning electron microscopy, and spectrometric techniques.

  10. Self assembled monolayer based liquid crystal biosensor for free cholesterol detection

    NASA Astrophysics Data System (ADS)

    Tyagi, Mukta; Chandran, Achu; Joshi, Tilak; Prakash, Jai; Agrawal, V. V.; Biradar, A. M.

    2014-04-01

    A unique cholesterol oxidase (ChOx) liquid crystal (LC) biosensor, based on the disruption of orientation in LCs, is developed for cholesterol detection. A self-assembled monolayer (SAM) of Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP) and (3-Aminopropyl)trimethoxy-silane (APTMS) is prepared on a glass plate by adsorption. The enzyme (ChOx) is immobilized on SAM surface for 12 h before utilizing the film for biosensing purpose. LC based biosensing study is conducted on SAM/ChOx/LC (5CB) cells for cholesterol concentrations ranging from 10 mg/dl to 250 mg/dl. The sensing mechanism has been verified through polarizing optical microscopy, scanning electron microscopy, and spectrometric techniques.

  11. Liquid crystal based biosensors for bile acid detection

    NASA Astrophysics Data System (ADS)

    He, Sihui; Liang, Wenlang; Tanner, Colleen; Fang, Jiyu; Wu, Shin-Tson

    2013-03-01

    The concentration level of bile acids is a useful indicator for early diagnosis of liver diseases. The prevalent measurement method in detecting bile acids is the chromatography coupled with mass spectrometry, which is precise yet expensive. Here we present a biosensor platform based on liquid crystal (LC) films for the detection of cholic acid (CA). This platform has the advantage of low cost, label-free, solution phase detection and simple analysis. In this platform, LC film of 4-Cyano-4'-pentylbiphenyl (5CB) was hosted by a copper grid supported with a polyimide-coated glass substrate. By immersing into sodium dodecyl sulfate (SDS) solution, the LC film was coated with SDS which induced a homeotropic anchoring of 5CB. Addition of CA introduced competitive adsorption between CA and SDS at the interface, triggering a transition from homeotropic to homogeneous anchoring. The detection limit can be tuned by changing the pH value of the solution from 12uM to 170uM.

  12. Hydrogenated amorphous silicon nitride photonic crystals for improved-performance surface electromagnetic wave biosensors

    PubMed Central

    Sinibaldi, Alberto; Descrovi, Emiliano; Giorgis, Fabrizio; Dominici, Lorenzo; Ballarini, Mirko; Mandracci, Pietro; Danz, Norbert; Michelotti, Francesco

    2012-01-01

    We exploit the properties of surface electromagnetic waves propagating at the surface of finite one dimensional photonic crystals to improve the performance of optical biosensors with respect to the standard surface plasmon resonance approach. We demonstrate that the hydrogenated amorphous silicon nitride technology is a versatile platform for fabricating one dimensional photonic crystals with any desirable design and operating in a wide wavelength range, from the visible to the near infrared. We prepared sensors based on photonic crystals sustaining either guided modes or surface electromagnetic waves, also known as Bloch surface waves. We carried out for the first time a direct experimental comparison of their sensitivity and figure of merit with surface plasmon polaritons on metal layers, by making use of a commercial surface plasmon resonance instrument that was slightly adapted for the experiments. Our measurements demonstrate that the Bloch surface waves on silicon nitride photonic crystals outperform surface plasmon polaritons by a factor 1.3 in terms of figure of merit. PMID:23082282

  13. Biosensor architecture for enhanced disease diagnostics: lab-in-a-photonic-crystal.

    PubMed

    Feng, Shuai; Jiang, Jian-Hua; Rashid, Abdullah Al; John, Sajeev

    2016-05-30

    A conceptual lab-in-a-photonic-crystal biosensor is demonstrated that can multiplex four or more distinct disease-markers and distinguish their presence and combinations simultaneously with unique spectral fingerprints. This biosensor consists of a photonic-band-gap, multi-mode waveguide coupled to surface modes on either side, encased in a glass slide with microfluidic channels. The spectral fingerprints consist of multiple peaks in optical transmission vs. frequency that respond sensitively and uniquely in both frequency shift and nonmonotonic change of peak transmittance levels to various analyte bindings. This special property enables complete, logical determination of twelve different combinations of four distinct disease-markers through one scan of the transmission spectrum. The results reveal unique phenomena such as switching between the strong-coupling and weak-coupling combinations of surface states by analyte binding at different locations along the central waveguide. The unconventional transmission spectra are explained using a Landauer-Büttiker, multiple-scattering, transmission theory that reproduces the main features of the exact finite-difference-time-domain simulation. PMID:27410136

  14. Thiol- and biotin-labeled probes for oligonucleotide quartz crystal microbalance biosensors of microalga alexandrium minutum.

    PubMed

    Lazerges, Mathieu; Perrot, Hubert; Rabehagasoa, Niriniony; Compère, Chantal

    2012-01-01

    Two quartz crystal microbalance oligonucleotide biosensors of a toxic microalga gene sequence (Alexandrium Minutum) have been designed. Grafting on a gold surface of 20-base thiol- or biotin-labeled probe, and selective hybridization with the complementary 20-base target, have been monitored in situ with a 27 MHz quartz crystal microbalance under controlled hydrodynamic conditions. The frequency of the set up is stable to within a few hertz, corresponding to the nanogram scale, for three hour experiments. DNA recognition by the two biosensors is efficient and selective. Hybridization kinetic curves indicate that the biosensor designed with the thiol-labeled probe is more sensitive, and that the biosensor designed with the biotin-labeled probe has a shorter time response and a higher hybridization efficiency. PMID:25585927

  15. Thiol- and Biotin-Labeled Probes for Oligonucleotide Quartz Crystal Microbalance Biosensors of Microalga Alexandrium Minutum

    PubMed Central

    Lazerges, Mathieu; Perrot, Hubert; Rabehagasoa, Niriniony; Compère, Chantal

    2012-01-01

    Two quartz crystal microbalance oligonucleotide biosensors of a toxic microalga gene sequence (Alexandrium Minutum) have been designed. Grafting on a gold surface of 20-base thiol- or biotin-labeled probe, and selective hybridization with the complementary 20-base target, have been monitored in situ with a 27 MHz quartz crystal microbalance under controlled hydrodynamic conditions. The frequency of the set up is stable to within a few hertz, corresponding to the nanogram scale, for three hour experiments. DNA recognition by the two biosensors is efficient and selective. Hybridization kinetic curves indicate that the biosensor designed with the thiol-labeled probe is more sensitive, and that the biosensor designed with the biotin-labeled probe has a shorter time response and a higher hybridization efficiency. PMID:25585927

  16. Fiber Optic Surface Plasmon Resonance-Based Biosensor Technique: Fabrication, Advancement, and Application.

    PubMed

    Liang, Gaoling; Luo, Zewei; Liu, Kunping; Wang, Yimin; Dai, Jianxiong; Duan, Yixiang

    2016-05-01

    Fiber optic-based biosensors with surface plasmon resonance (SPR) technology are advanced label-free optical biosensing methods. They have brought tremendous progress in the sensing of various chemical and biological species. This review summarizes four sensing configurations (prism, grating, waveguide, and fiber optic) with two ways, attenuated total reflection (ATR) and diffraction, to excite the surface plasmons. Meanwhile, the designs of different probes (U-bent, tapered, and other probes) are also described. Finally, four major types of biosensors, immunosensor, DNA biosensor, enzyme biosensor, and living cell biosensor, are discussed in detail for their sensing principles and applications. Future prospects of fiber optic-based SPR sensor technology are discussed. PMID:27119268

  17. Analysis of an integrated optic micro racetrack resonator based biosensor

    NASA Astrophysics Data System (ADS)

    Malathi, S.; Hegde, Gopalkrishna; Srinivas, T.; Roy, Ugra M.

    2014-06-01

    Silicon-On- Insulator (SOI) technology has huge potential in fabricating compact devices for various applications such as integrated optic waveguides, directional couplers, resonators etc. In this work, we present the analysis of a biosensor based on an integrated optic racetrack resonator, interrogated by a bus waveguide. The biomaterial is applied as a cladding layer. Here we analyze the coupling between the resonator and the bus waveguide, and its dependence on the bio layer. In traditional analysis, the effective refractive index and resonator total path length are the factors influencing the resonant wavelength. Our analysis shows that all parametric values decrease with increase in waveguide width and spacing. The inclusion of waveguide mode overlap and perturbation in coupled mode equation results in enhanced resonator sensitivity of an order of magnitude

  18. Multiplex fiber-optic biosensor using multiple particle plasmon resonances

    NASA Astrophysics Data System (ADS)

    Lin, Hsing-Ying; Huang, Chen-Han; Liu, Yu-Chia; Huang, Kuo-Wei; Chau, Lai-Kwan

    2012-02-01

    Multiplex fiber-optic biosensor implemented by integrating multiple particle plasmon resonances (PPRs), molecular bioassays, and microfluidics is successfully demonstrated. The multiple PPRs are achieved by chemical immobilization of silver nanoparticles (AgNPs) and gold nanorods (AuNRs) separately on two unclad portions of an optical fiber. The difference in morphology and nature of material of AgNPs and AuNRs are exploited to yield multiple plasmonic absorptions at 405 and 780 nm in the absorption spectrum measured from optical fiber by white light source illumination. Through the coaxial excitation of light-emitting diodes (LEDs) with 405 and 800 nm wavelengths, the distinct PPRs are advantageous for real-time and simultaneous detection of multiple analyte-probe pairs as AgNPs and AuNRs are separately functionalized with specific bio-probes. Here, the multi-window fiber-optic particle plasmon resonance (FO-PPR) biosensor has been shown to be capable of simultaneously detecting anti-dinitrophenyl antibody (anti-DNP, MW = 220 kDa) via N-(2,4-dinitrophenyl)-6-aminohexanoic acid (DNP, MW = 297.27 Da) functionalized AgNPs and streptavidin (MW = 75 kDa) via N-(3-aminopropyl)biotinamide trifluoroacetate (biotin, MW = 414.44 Da) functionalized AuNRs. The multiplex sensing chip possesses several advantages, including rapid and parallel detection of multiple analytes on a single chip, minimized sample to sample variation, reduced amount of sensor chip, and reduced analyte volume, hence it is ideally suitable for high-throughput multiplex biochemical sensing applications.

  19. BIOSENSORS

    EPA Science Inventory

    It has recently been proposed under the International Union of Pure and Applied Chemistry (IUPAC) Commission that biosensors be regarded as a subgroup of chemical sensors in which a biologically based mechanism is used for detection of the analyte. hemical sensors are defined und...

  20. Label-Free Biosensor Imaging on Photonic Crystal Surfaces

    PubMed Central

    Zhuo, Yue; Cunningham, Brian T.

    2015-01-01

    We review the development and application of nanostructured photonic crystal surfaces and a hyperspectral reflectance imaging detection instrument which, when used together, represent a new form of optical microscopy that enables label-free, quantitative, and kinetic monitoring of biomaterial interaction with substrate surfaces. Photonic Crystal Enhanced Microscopy (PCEM) has been used to detect broad classes of materials which include dielectric nanoparticles, metal plasmonic nanoparticles, biomolecular layers, and live cells. Because PCEM does not require cytotoxic stains or photobleachable fluorescent dyes, it is especially useful for monitoring the long-term interactions of cells with extracellular matrix surfaces. PCEM is only sensitive to the attachment of cell components within ~200 nm of the photonic crystal surface, which may correspond to the region of most interest for adhesion processes that involve stem cell differentiation, chemotaxis, and metastasis. PCEM has also demonstrated sufficient sensitivity for sensing nanoparticle contrast agents that are roughly the same size as protein molecules, which may enable applications in “digital” diagnostics with single molecule sensing resolution. We will review PCEM’s development history, operating principles, nanostructure design, and imaging modalities that enable tracking of optical scatterers, emitters, absorbers, and centers of dielectric permittivity. PMID:26343684

  1. Label-Free Biosensor Imaging on Photonic Crystal Surfaces.

    PubMed

    Zhuo, Yue; Cunningham, Brian T

    2015-01-01

    We review the development and application of nanostructured photonic crystal surfaces and a hyperspectral reflectance imaging detection instrument which, when used together, represent a new form of optical microscopy that enables label-free, quantitative, and kinetic monitoring of biomaterial interaction with substrate surfaces. Photonic Crystal Enhanced Microscopy (PCEM) has been used to detect broad classes of materials which include dielectric nanoparticles, metal plasmonic nanoparticles, biomolecular layers, and live cells. Because PCEM does not require cytotoxic stains or photobleachable fluorescent dyes, it is especially useful for monitoring the long-term interactions of cells with extracellular matrix surfaces. PCEM is only sensitive to the attachment of cell components within ~200 nm of the photonic crystal surface, which may correspond to the region of most interest for adhesion processes that involve stem cell differentiation, chemotaxis, and metastasis. PCEM has also demonstrated sufficient sensitivity for sensing nanoparticle contrast agents that are roughly the same size as protein molecules, which may enable applications in "digital" diagnostics with single molecule sensing resolution. We will review PCEM's development history, operating principles, nanostructure design, and imaging modalities that enable tracking of optical scatterers, emitters, absorbers, and centers of dielectric permittivity. PMID:26343684

  2. Surface plasmon resonance based fiber optic glucose biosensor

    NASA Astrophysics Data System (ADS)

    Srivastava, Sachin K.; Verma, Roli; Gupta, Banshi D.

    2012-02-01

    A surface plasmon resonance (SPR) based fiber optic biosensor has been fabricated and characterized for the detection of blood glucose. Optical fiber sensor was fabricated by first coating a 50 nm thick gold film on the bare core of optical fiber and then immobilizing glucose oxidase (GOx) over it. Aqueous glucose solutions of different concentrations were prepared. To mimic the blood glucose levels, the concentration of glucose solutions were kept equal to that in human blood. The refractive indices of these sample solutions were equal to that of water up to third decimal place. SPR spectra for the sensor were recorded for these glucose solutions. When the glucose comes in contact to glucose oxidase, chemical reactions take place and as a result, the refractive index of the immobilized GOx film changes, giving rise to a shift in the resonance wavelength. Unlike electrochemical sensors, the present sensor is based on optics and can be miniaturized because of optical fiber. The present study provides a different approach for blood glucose sensing and may be commercialized after optimization of certain parameters.

  3. Research on optical biosensor with up-converting phosphor marker

    NASA Astrophysics Data System (ADS)

    Zhao, Yongkai; Zhou, Lei; Wang, Jing; Huang, Lihua; Yan, Zhongqiang; Huang, Huijie; Yang, Ruifu; Liu, Lei; Ren, Bingqiang; Wang, Xiangzhao

    2006-08-01

    An optical biosensor with up-converting phosphor (UCP) marker is developed for the sensitive rapid immunoassay to the specific biomolecule. UCP can emit visible light when excited by infrared light. Through detecting and analyzing the content of UCP particles on the test strip after immunoreaction, the concentration of target analyte in the sample can be obtained. The detection sensitivity to plague IgG is better than 5 ng/ml; to plague FI-Ab is better than 100 pg/ml; to plague Yersinia pestis cell is better than 3*10^(4) CFU/ml. Good linear response characteristics and an excellent correlation (R2>=0.95) have been verified by quantitative detection results. In the practical application, detection results to 167 analytic samples have an excellent consistency with those obtained by reverse hemagglutination test. The up-converting phosphor technology (UPT) based biosensor has stable, reliable, and sensitive performances. It can meet the need of various bioassay applications.

  4. Sensitivity Improvement of Biosensors Using Si Ring Optical Resonators

    NASA Astrophysics Data System (ADS)

    Fukuyama, Masataka; Amemiya, Yoshiteru; Abe, Yosuke; Onishi, Yuto; Hirowatari, Anna; Terao, Kei; Ikeda, Takeshi; Kuroda, Akio; Yokoyama, Shin

    2011-04-01

    We have been demonstrating label-free detection of a variety of antigen-antibody reactions using Si ring optical resonators. Although the detection of biomarkers for the diagnosis of diseases generally requires high sensitivity of the order of 10-9 g/ml, the detection sensitivity of our device is currently of the order of 10-6 g/ml. In this paper, we show that the sensitivity of 10-9 g/ml will be possible by adopting the following four strategies: (1) use of slot-type waveguides with light wavelength of 1.3 µm, (2) improvement of quality factor Q of the ring resonator by smoothing the surface roughness, (3) specific adsorption of the bioreceptor protein to the resonator surface, and (4) maintaining temperature within ±0.005 °C. We have also proposed the on-chip temperature compensation method without the need for temperature control of the sample. By combining the proposed approaches, the sensitivity of the biosensor will be improved by a factor of >100, thus realizing practical application of our Si ring biosensor.

  5. Label-free liquid crystal biosensor based on specific oligonucleotide probes for heavy metal ions.

    PubMed

    Yang, Shengyuan; Wu, Chao; Tan, Hui; Wu, Yan; Liao, Shuzhen; Wu, Zhaoyang; Shen, Guoli; Yu, Ruqin

    2013-01-01

    In this study, to enhance the capability of metal ions disturbing the orientation of liquid crystals (LCs), we designed a new label-free LC biosensor for the highly selective and sensitive detection of heavy metal ions. This strategy makes use of the target-induced DNA conformational change to enhance the disruption of target molecules for the orientation of LC leading to an amplified optical signal. The Hg(2+) ion, which possesses a unique property to bind specifically to two DNA thymine (T) bases, is used as a model heavy metal ion. In the presence of Hg(2+), the specific oligonucleotide probes form a conformational reorganization of the oligonucleotide probes from hairpin structure to duplex-like complexes. The duplex-like complexes are then bound on the triethoxysilylbutyraldehyde/N,N-dimethyl-N-octadecyl (3-aminopropyl) trimethoxysilyl chloride (TEA/DMOAP)-coated substrate modified with capture probes, which can greatly distort the orientational profile of LC, making the optical image of LC cell birefringent as a result. The optical signal of LC sensor has a visible change at the Hg(2+) concentration of low to 0.1 nM, showing good detection sensitivity. The cost-effective LC sensing method can translate the concentration signal of heavy metal ions in solution into the presence of DNA duplexes and is expected to be a sensitive detection platform for heavy metal ions and other small molecule monitors. PMID:23214408

  6. Recent Advances in Optical Biosensors for Environmental Monitoring and Early Warning

    PubMed Central

    Long, Feng; Zhu, Anna; Shi, Hanchang

    2013-01-01

    The growing number of pollutants requires the development of innovative analytical devices that are precise, sensitive, specific, rapid, and easy-to-use to meet the increasing demand for legislative actions on environmental pollution control and early warning. Optical biosensors, as a powerful alternative to conventional analytical techniques, enable the highly sensitive, real-time, and high-frequency monitoring of pollutants without extensive sample preparation. This article reviews important advances in functional biorecognition materials (e.g., enzymes, aptamers, DNAzymes, antibodies and whole cells) that facilitate the increasing application of optical biosensors. This work further examines the significant improvements in optical biosensor instrumentation and their environmental applications. Innovative developments of optical biosensors for environmental pollution control and early warning are also discussed. PMID:24132229

  7. Biosensors for hepatitis B virus detection.

    PubMed

    Yao, Chun-Yan; Fu, Wei-Ling

    2014-09-21

    A biosensor is an analytical device used for the detection of analytes, which combines a biological component with a physicochemical detector. Recently, an increasing number of biosensors have been used in clinical research, for example, the blood glucose biosensor. This review focuses on the current state of biosensor research with respect to efficient, specific and rapid detection of hepatitis B virus (HBV). The biosensors developed based on different techniques, including optical methods (e.g., surface plasmon resonance), acoustic wave technologies (e.g., quartz crystal microbalance), electrochemistry (amperometry, voltammetry and impedance) and novel nanotechnology, are also discussed. PMID:25253948

  8. Liquid-Crystal Optical Correlator

    NASA Technical Reports Server (NTRS)

    Liu, Hua-Kuang

    1989-01-01

    Optical correlator uses commercially-available liquid-crystal television (LCTV) screen as spatial light modulator. Correlations with this device done at video frame rates, making such operations as bar-code recognition possible at reasonable cost. With further development, such correlator useful in automation, robotic vision, and optical image processing.

  9. Diamond turning of optical crystals

    SciTech Connect

    Saito, T.T.; Syn, C.K.; Fuchs, B.A.; Velsko, S.P.

    1990-03-01

    Diamond turning (DT) has proven to be a cost effective optical fabrication technique for both aspherical and spherical/flat figures when precise geometrical tolerances are important. We are interested in the DT of crystals for several reasons. DT has been very effective to insure requisite accurate geometrical orientation of optical surfaces to crystalline axes for frequency conversion applications. Also, DT can achieve figure up to the edge of the crystal. Another key DT benefit is enhanced laser damage threshold, which we feel in part is due to the freedom of the surface from polishing impurities. Several important issues for diamond turning optical crystals are the tool wear, associated surface finish, and laser damage properties. We have found that careful selection and control of diamond turning parameters can yield production techniques for crystals previously considered incompatible with diamond turning. 8 refs., 2 tabs.

  10. Highly sensitive color-indicating and quantitative biosensor based on cholesteric liquid crystal

    PubMed Central

    Hsiao, Yu-Cheng; Sung, Yu-Chien; Lee, Mon-Juan; Lee, Wei

    2015-01-01

    Liquid crystal (LC)-based biosensors employ highly sensitive interfaces between the alignment layers and LCs to detect biomolecules and their interactions. Present techniques based on optical texture observation of the homeotropic-to-planar response of nematic LCs are limited by their quantitative reproducibility of results, indicating that both the accuracy and reliability of LC-based detection require further improvements. Here we show that cholesteric LC (CLC) can be used as a novel sensing element in the design of an alternative LC-based biosensing device. The chirality of the vertically anchored (VA) CLC was exploited in the detection of bovine serum albumin (BSA), a protein standard commonly used in protein quantitation. The color appearance and the corresponding transmission spectrum of the cholesteric phase changed with the concentration of BSA, by which a detection limit of 1 fg/ml was observed. The optical response of the VA CLC interface offers a simple and inexpensive platform for highly sensitive and naked-eye color-indicating detection of biomolecules, and, thus, may facilitate the development of point-of-care devices for the detection of disease-related biomarkers. PMID:26713215

  11. Highly sensitive color-indicating and quantitative biosensor based on cholesteric liquid crystal.

    PubMed

    Hsiao, Yu-Cheng; Sung, Yu-Chien; Lee, Mon-Juan; Lee, Wei

    2015-12-01

    Liquid crystal (LC)-based biosensors employ highly sensitive interfaces between the alignment layers and LCs to detect biomolecules and their interactions. Present techniques based on optical texture observation of the homeotropic-to-planar response of nematic LCs are limited by their quantitative reproducibility of results, indicating that both the accuracy and reliability of LC-based detection require further improvements. Here we show that cholesteric LC (CLC) can be used as a novel sensing element in the design of an alternative LC-based biosensing device. The chirality of the vertically anchored (VA) CLC was exploited in the detection of bovine serum albumin (BSA), a protein standard commonly used in protein quantitation. The color appearance and the corresponding transmission spectrum of the cholesteric phase changed with the concentration of BSA, by which a detection limit of 1 fg/ml was observed. The optical response of the VA CLC interface offers a simple and inexpensive platform for highly sensitive and naked-eye color-indicating detection of biomolecules, and, thus, may facilitate the development of point-of-care devices for the detection of disease-related biomarkers. PMID:26713215

  12. Study and development of label-free optical biosensors for biomedical applications

    NASA Astrophysics Data System (ADS)

    Choi, Charles J.

    For the majority of assays currently performed, fluorescent or colorimetric chemical labels are commonly attached to the molecules under study so that they may be readily visualized. The methods of using labels to track biomolecular binding events are very sensitive and effective, and are employed as standardized assay protocol across research labs worldwide. However, using labels induces experimental uncertainties due to the effect of the label on molecular conformation, active binding sites, or inability to find an appropriate label that functions equivalently for all molecules in an experiment. Therefore, the ability to perform highly sensitive biochemical detection without the use of fluorescent labels would further simplify assay protocols and would provide quantitative kinetic data, while removing experimental artifacts from fluorescent quenching, shelf-life, and background fluorescence phenomena. In view of the advantages mentioned above, the study and development of optical label-free sensor technologies have been undertaken here. In general, label-free photonic crystal (PC) biosensors and metal nanodome array surface-enhanced Raman scattering (SERS) substrates, both of which are fabricated by nanoreplica molding process, have been used as the method to attack the problem. Chapter 1 shows the work on PC label-free biosensor incorporated microfluidic network for bioassay performance enhancement and kinetic reaction rate constant determination. Chapter 2 describes the work on theoretical and experimental comparison of label-free biosensing in microplate, microfluidic, and spot-based affinity capture assays. Chapter 3 shows the work on integration of PC biosensor with actuate-to-open valve microfluidic chip for pL-volume combinatorial mixing and screening application. In Chapter 4, the development and characterization of SERS nanodome array is shown. Lastly, Chapter 5 describes SERS nanodome sensor incorporated tubing for point-of-care monitoring of

  13. Multiplexed label-free optical biosensor for medical diagnostics.

    PubMed

    Bottazzi, Barbara; Fornasari, Lucia; Frangolho, Ana; Giudicatti, Silvia; Mantovani, Alberto; Marabelli, Franco; Marchesini, Gerardo; Pellacani, Paola; Therisod, Rita; Valsesia, Andrea

    2014-01-01

    This paper describes a new multiplexed label-free biosensor. The detection technology is based on nanostructured gold-polymer surfaces. These surfaces support surface plasmon resonance modes that can be probed by a miniaturized optical setup. The optical characterization of the sensing chip shows the sensitivity and the limit-of-detection to refractive index changes. Moreover, by studying the progressive adhesion of molecular monolayers of polyelectrolytes, the decay of the plasmonic mode electric field above the surface has been reconstructed. A multiplexed label-free biosensing device is then described and characterized in terms of sensitivity, lateral resolution, and sensitivity to a model biological assay. The sensitivity in imaging mode of the device is of the order of 10-6 refractive index units, while the measured lateral resolution is 6.25 μm within a field of view of several tenths of mm2, making the instrument unique in terms of multiplexing capability. Finally, the proof-of-concept application of the technology as a point-of-care diagnostic tool for an inflammatory marker is demonstrated. PMID:24474511

  14. Deep-Probe Optical Waveguides for Chemical and Biosensors

    NASA Astrophysics Data System (ADS)

    Zourob, Mohammed; Skivesen, Nina; Horvath, Robert; Mohr, Stephan; Goddard, Nicholas J.

    Typical evanescent wave biosensors generate an electromagnetic wave at the sensor surface that penetrates 100-200 nm into the analysed medium. This has proven to be a highly sensitive tool to monitor refractive index changes in the close vicinity of the sensor surface. The sensitivity of such sensors can be enhanced significantly to monitor interactions caused by large micron scale objects such as bacterial and mammalian cells by increasing the penetration depth of the evanescent field. Recently, different formats of deep-probe optical waveguides including reverse waveguides (RW) based on low refractive index substrates (below 1.33) and metal-clad leaky waveguides (MCLW) have been developed for various sensing applications. These sensors are designed to maximize the overlap between the optical mode and the adlayer (superstrate layer) to be sensed. Increasing the penetration depth of the evanescent field opens up new perspectives for the detection of larger biological objects as it accommodates the majority of their body within the evanescent field. RWs use substrate materials with lower refractive index than that of the monitored superstrate layer (aqueous solution). In MCLWs, a thin metal layer is inserted between the substrate and the thicker waveguide layer. These sensor designs facilitate both increasing and tuning the penetration depth of the modes into the monitored aqueous solution and thereby significantly extend the range of possible application areas of optical waveguide sensors. The developed devices have been used for a range of biosensing applications, including the detection of bacteria, mammalian cells, organophosphorous pesticides and glucose using refractive index changes, absorbance and fluorescence monitoring. Integrating deep-probe sensors with an external electrical field or ultrasonic standing waves shortens analysis time significantly and reduces non-specific binding due to enhanced diffusion of analytes to the immobilized recognition

  15. Liquid crystal assisted optical fibres.

    PubMed

    Wahle, M; Kitzerow, H-S

    2014-01-13

    Microstructured fibres which consist of a circular step index core and a liquid crystal inclusion running parallel to this core are investigated. The attenuation and electro-optic effects of light coupled into the core are measured. Coupled mode theory is used to study the interaction of core modes with the liquid crystal inclusion. The experimental and theoretical results show that these fibres can exhibit attenuation below 0.16 dB cm(-1) in off-resonant wavelength regions and still have significant electro-optic effects which can lead to a polarisation extinction of 6 dB cm(-1). PMID:24514987

  16. Four-channel label-free photonic crystal biosensor using nanocavity resonators

    NASA Astrophysics Data System (ADS)

    Olyaee, Saeed; Najafgholinezhad, Samira; Alipour Banaei, Hamed

    2013-09-01

    In this paper, we design and characterize a novel small size four-channel biosensor based on the two-dimensional photonic crystal with introducing waveguides and nano-cavities in the hexagonal lattice of air pores in the silicon slab. By removing a group of air pores, waveguides are achieved, and nano-cavities are shaped by modifying the radius of air pores. Highly parallel operation of this biosensor due to the special architecture is the capability of the designed structure. The biomaterials which are suspended in a liquid medium inside nano-cavities cause effective refractive index changes which lead to the resonant wavelength shift in the output terminal. According to results, with increasing the refractive index of nano-cavities, resonant wavelengths shifts to longer values. For biochemical sensing like DNA molecule and protein and for the refractive index detection, this novel designed biosensor can be utilized.

  17. Optical fiber SPR biosensor with sandwich assay for the detection of prostate specific antigen

    NASA Astrophysics Data System (ADS)

    Jang, Hyun Soo; Park, Kwang No; Kang, Chang Duk; Kim, Jun Pyo; Sim, Sang Jun; Lee, Kyung Shik

    2009-07-01

    We present a new, sensitive, few mode fiber (FMF) surface plasmon resonance (SPR) biosensor with a sandwich assay for the detection of PSA. The side-polished FMF biosensor does not need a polarizer and a thin high-index overlayer. The optical sensitivity of the SPR sensor was determined as 2.5 × 10 -6 RIU. In the SPR PSA sensor, the SPR signals were amplified by a factor of 6 in average over no secondary antibody, using the sandwich assay. The proposed FMF SPR biosensor has great potential for real-time analysis of immune reaction between biomolecules and the advantages of high-sensitivity and label-free detection.

  18. Investigation of Optical Properties of Biomolecular Materials for Developing a Novel Fiber Optic Biosensor.

    NASA Astrophysics Data System (ADS)

    Gao, Harry Hong

    1995-01-01

    Recently considerable efforts have been devoted to the development of optical biosensors for applications such as environmental monitoring and biomedical technology. The research described in this thesis focuses on the development of a novel fiber optic biosensor system for pesticide detection based on enzyme catalyzed chemiluminescence. To optimize the collection efficiency, the tapering effect of a fiber tip has been studied in different cases of light source distribution utilizing fluorescence technique. Our results indicate that a continuously tapered tip with the largest tapering angle is the most efficient configuration when the light source is in a "thick" layer ({> }1 μm) while a combination tapered tip is the best configuration when the light source is either in a thin layer ({<}1 mu m) or is uniformly distributed around the tip. Three immobilization schemes have been investigated. The molecular self assembly approach takes advantage of the strong binding between streptavidin and biotin, with a biotinylated polymer as a support. The sol-gel process has the advantage of encapsulating biomolecules in a transparent glass. A photodynamic protein phycoerythrin has been successfully immobilized on a fiber surface by both techniques. The multilayer enzyme assembly we developed utilizes a bifunctional amino coupling agent to link between different layers of enzyme through chemical bonding. The method offers the flexibility of controlling the number of enzymes on a fiber surface. Multilayer of alkaline phosphatase have been characterized using various techniques including chemiluminescence, ellipsometry and surface plasma resonance. The results indicated that at least 3 layers of enzyme can be assembled on a fiber surface. With this approach, it is possible to immobilize different kinds of enzyme on a fiber surface for biosensors based on a multi-enzyme system. Based on the studies of tapered tip and immobilization schemes, a novel fiber optic biosensor system for

  19. Active layer identification of photonic crystal waveguide biosensor chip for the detection of Escherichia coli

    NASA Astrophysics Data System (ADS)

    Painam, Balveer; Kaler, Rajinder S.; Kumar, Mukesh

    2016-07-01

    This work represents experimental and simulation analysis of photonic crystal waveguide (PCW)-based biosensor structures, which is used for detection of the Escherichia coli (E. coli) cell. A method is adopted for E. coli culture to measure length, diameter, and refractive index to finalize the structural design and to verify the suitability of PCW as a biosensor. This method is tested using DH5α strains of E. coli. The typical precisions of measurements are varied in ranges from 1.132 to 1.825 μm and from 0.447 to 0.66 μm for pathogen's length and diameter, respectively. The measured distribution of samples over length and diameter are in correlation with the measurements performed by scanning electron microscope. After obtaining average length and diameter of cylindrical shaped E. coli cell, we consider these values for simulation analysis of designed PCW biosensor. E. coli cell is trapped in the middle of the PCW biosensor having three different types of waveguides, i.e., gallium arsenide/silicon dioxide (GaAs/SiO2), silicon/silicon dioxide (Si/SiO2), or silicon nitride/silicon dioxide (Si3N4/SiO2) to observe the maximum resonance shift and sensitivity. It is observed from the simulation data analysis that GaAs/SiO2 is the preferred PCW biosensor for the identification of E. coli.

  20. Planar Photonic Crystal Biosensor for Quantitative Label-Free Cell Attachment Microscopy

    PubMed Central

    Chen, Weili; Long, Kenneth D.; Kurniawan, Jonas; Hung, Margaret; Yu, Hojeong; Harley, Brendan A.

    2016-01-01

    In this study, a planar-surface photonic crystal (PC) biosensor for quantitative, kinetic, label-free imaging of cell–surface interactions is demonstrated. The planar biosensor surface eliminates external stimuli to the cells caused by substrate topography to more accurately reflect smooth surface environment encountered by many cell types in vitro. Here, a fabrication approach that combines nanoreplica molding and a horizontal dipping process is used to planarize the surface of the PC biosensor. The planar PC biosensor maintains a high detection sensitivity that enables the monitoring of live cell–substrate interactions with spatial resolution sufficient for observing intracellular attachment strength gradients and the extensions of filopodia from the cell body. The evolution of cell morphology during the attachment and spreading process of 3T3 fibroblast cells is compared between planar and grating-structured PC biosensors. The planar surface effectively eliminates the directionally biased cellular attachment behaviors that are observed on the grating-structured surface. This work represents an important step forward in the development of label-free techniques for observing cellular processes without unintended external environmental modulation. PMID:26877910

  1. An immuno-biosensor system based on quartz crystal microbalance for avian influenza virus detection

    NASA Astrophysics Data System (ADS)

    Liu, Shengping; Chen, Guoming; Zhou, Qi; Wei, Yunlong

    2007-12-01

    For the quick detection of Avian Influenza Virus (AIV), a biosensor based on Quartz Crystal Microbalance (QCM) was fabricated according to the specific bonding principle between antibody and antigen. Staphylococcal Protein A (SPA) was extracted from Staphylococcus and purified. Then SPA was coated on the surface of QCM for immobilizing AIV monoclonal antibodies. The use of AIV monoclonal antibody could enhance the specificity of the immuno-biosensor. A multi-channel piezoelectricity detection system for the immuno-biosensor was developed. The system can work for the quick detection of AIV antigen in the case of the entirely aqueous status owe to one special oscillating circuit designed in this work. The optimum conditions of SPA coating and AIV monoclonal antibody immobilization were investigated utilizing the multi-channel detection system. The preliminary application of the immuno-biosensor system for detection of AIV was evaluated. Results indicate that the immuno-biosensor system can detect the AIV antigens with a linear range of 3-200ng/ml. The system can accomplish the detection of AIV antigens around 40 minutes.

  2. Optical tweezers on biaxial crystal

    NASA Astrophysics Data System (ADS)

    Angelsky, Oleg V.; Maksimyak, Andrew P.; Maksimyak, Peter P.

    2009-10-01

    In this paper, we propose optical tweezers based on a biaxial crystal. To control the movement of opaque particles, we use the shift polarization interferometer. The results of experimental study of laser tweezers are shown. We demonstrates movement of a microparticle of toner using singular-optical trap, rotate a particle due to orbital momentum, conversion of two traps when changing the plane of polarizer transmission and converging of two traps.

  3. Label-free Detection of Cardiac Troponin I with a Photonic Crystal Biosensor

    PubMed Central

    Zhang, Bailin; Morales, Andres W.; Peterson, Ralph; Tang, Liang; Ye, Jing Yong

    2014-01-01

    A biosensor has been developed with a photonic crystal structure used in a total-internal-reflection (PC-TIR) configuration for label-free detection of a cardiac biomarker: Troponin I (cTnI). In contrast to a conventional optical microcavity that has a closed structure with its cavity layer sandwiched between two high-reflection surfaces, the PC-TIR configuration creates a unique open microcavity, which allows its cavity layer (sensing layer) to be easily functionalized and directly exposed to analyte molecules for bioassays. In this study, a PC-TIR sensor has been used for the label-free measurements of cardiac biomarkers by monitoring the changes in the resonant condition of the cavity due to biomolecular binding processes. Antibodies against cTnI are immobilized on the sensor surface for specific detection of cTnI with a wide range of concentrations. Detection limit of cTnI with a concentration as low as 0.1 ng mL−1 has been achieved. PMID:24632136

  4. Optical biosensors. Monitoring studies of glycopeptide antibiotic fermentation using white light interference.

    PubMed

    Tünnemann, R; Mehlmann, M; Süssmuth, R D; Bühler, B; Pelzer, S; Wohlleben, W; Fiedler, H P; Wiesmüller, K H; Gauglitz, G; Jung, G

    2001-09-01

    This paper describes the design, characterization, and use of an optical biosensor suited for the process control of biotechnological processes. The detector principle is based on reflectometric interference spectroscopy (RIfS). RIfS enables a label-free, product-specific monitoring, with a future outline for on-line process control. The potential of the RIfS biosensor is exemplified by the qualitative and quantitative monitoring of the microbial production of vancomycin-type glycopeptide antibiotics. PMID:11569825

  5. Optics of globular photonic crystals

    SciTech Connect

    Gorelik, V S

    2007-05-31

    The results of experimental and theoretical studies of the optical properties of globular photonic crystals - new physical objects having a crystal structure with the lattice period exceeding considerably the atomic size, are presented. As globular photonic crystals, artificial opal matrices consisting of close-packed silica globules of diameter {approx}200 nm were used. The reflection spectra of these objects characterising the parameters of photonic bands existing in these crystals in the visible spectral region are presented. The idealised models of the energy band structure of photonic crystals investigated in the review give analytic dispersion dependences for the group velocity and the effective photon mass in a globular photonic crystal. The characteristics of secondary emission excited in globular photonic crystals by monochromatic and broadband radiation are presented. The results of investigations of single-photon-excited delayed scattering of light observed in globular photonic crystals exposed to cw UV radiation and radiation from a repetitively pulsed copper vapour laser are presented. The possibilities of using globular photonic crystals as active media for lasing in different spectral regions are considered. It is proposed to use globular photonic crystals as sensitive sensors in optoelectronic devices for molecular analysis of organic and inorganic materials by the modern methods of laser spectroscopy. The results of experimental studies of spontaneous and stimulated globular scattering of light are discussed. The conditions for observing resonance and two-photon-excited delayed scattering of light are found. The possibility of accumulation and localisation of the laser radiation energy inside a globular photonic crystal is reported. (review)

  6. Fiber-Optic Chemical Sensors and Fiber-Optic Bio-Sensors

    PubMed Central

    Pospíšilová, Marie; Kuncová, Gabriela; Trögl, Josef

    2015-01-01

    This review summarizes principles and current stage of development of fiber-optic chemical sensors (FOCS) and biosensors (FOBS). Fiber optic sensor (FOS) systems use the ability of optical fibers (OF) to guide the light in the spectral range from ultraviolet (UV) (180 nm) up to middle infrared (IR) (10 µm) and modulation of guided light by the parameters of the surrounding environment of the OF core. The introduction of OF in the sensor systems has brought advantages such as measurement in flammable and explosive environments, immunity to electrical noises, miniaturization, geometrical flexibility, measurement of small sample volumes, remote sensing in inaccessible sites or harsh environments and multi-sensing. The review comprises briefly the theory of OF elaborated for sensors, techniques of fabrications and analytical results reached with fiber-optic chemical and biological sensors. PMID:26437407

  7. Comparison of the efficiency control of mycotoxins by some optical immune biosensors

    NASA Astrophysics Data System (ADS)

    Slyshyk, N. F.; Starodub, N. F.

    2013-11-01

    It was compared the efficiency of patulin control at the application of such optical biosensors which were based on the surface plasmon resonance (SPR) and nano-porous silicon (sNPS). In last case the intensity of the immune reaction was registered by measuring level of chemiluminescence (ChL) or photocurrent of nPS. The sensitivity of this mycotoxin determination by first type of immune biosensor was 0.05-10 mg/L Approximately the same sensitivity as well as the overall time analysis were demonstrated by the immune biosensor based on the nPS too. Nevertheless, the last type of biosensor was simpler in technical aspect and the cost of analysis was cheapest. That is why, it was recommend the nPS based immune biosensor for wide screening application and SPR one for some additional control or verification of preliminary obtained results. In this article a special attention was given to condition of sample preparation for analysis, in particular, micotoxin extraction from potao and some juices. Moreover, it was compared the efficiency of the above mentioned immune biosensors with such traditional approach of mycotoxin determination as the ELISA-method. In the result of investigation and discussion of obtained data it was concluded that both type of the immune biosensors are able to fulfill modern practice demand in respect sensitivity, rapidity, simplicity and cheapness of analysis.

  8. Optical trapping in liquid crystals

    NASA Astrophysics Data System (ADS)

    Simoni, F.; Lucchetti, L.; Criante, L.; Bracalente, F.; Aieta, F.

    2010-08-01

    Optical trapping and manipulation of micrometric silica particles dispersed in a nematic liquid crystal is reported. Several kind of samples are considered: homeotropic and planar undoped cells and homeotropic and planar cells doped by a small amount of the azo-dye Methyl-Red. The incident light intensity is over the threshold for optical reorientation of the molecular director. The refractive index of the dispersed particles is lower than the ones of the liquid crystal therefore the usual conditions for laser trapping and manipulation are not fulfilled. Nevertheless optical trapping is possible and is closely related to the optical nonlinearity of the hosting liquid crystal1. Trapping in doped and undoped cells are compared and it is shown that in the first case intensity lower by more than one order of magnitude is required as compared to the one needed in undoped samples. The effect is faster and the structural forces are of longer range. The formation of bubble-gum like defects in doped samples under certain experimental conditions is also reported and discussed.

  9. Localized surface plasmon coupled fluorescence fiber-optic biosensor with gold nanoparticles.

    PubMed

    Hsieh, Bao-Yu; Chang, Ying-Feng; Ng, Ming-Yaw; Liu, Wei-Chih; Lin, Chao-Hsiung; Wu, Hsieh-Ting; Chou, Chien

    2007-05-01

    A novel fiber-optic biosensor based on a localized surface plasmon coupled fluorescence (LSPCF) system is proposed and developed. This biosensor consists of a biomolecular complex in a sandwich format of . It is immobilized on the surface of an optical fiber where a complex forms the fluorescence probe and is produced by mixing Cy5-labeled antibody and protein A conjugated gold nanoparticles (Au-PA). The LSPCF is excited by localized surface plasmon on the GNP surface where the evanescent field is applied near the core surface of the optical fiber. At the same time, the fluorescence signal is detected by a photomultiplier tube located beside the unclad optical fiber with high collection efficiency. Experimentally, this novel LSPCF biosensor is able to detect mouse immunoglobulin G (IgG) at a minimum concentration of 1 pg/mL (7 fM) during the biomolecular interaction of the IgG with anti-mouse IgG. The analysis is expanded by a discussion of the amplification of the LSPCF intensity by GNP coupling, and overall, this LSPCF biosensor is confirmed experimentally as a biosensor with very high sensitivity. PMID:17378542

  10. Optical Magnetometer Incorporating Photonic Crystals

    NASA Technical Reports Server (NTRS)

    Kulikov, Igor; Florescu, Lucia

    2007-01-01

    According to a proposal, photonic crystals would be used to greatly increase the sensitivities of optical magnetometers that are already regarded as ultrasensitive. The proposal applies, more specifically, to a state-of-the-art type of quantum coherent magnetometer that exploits the electromagnetically-induced-transparency (EIT) method for determining a small change in a magnetic field indirectly via measurement of the shift, induced by that change, in the hyperfine levels of resonant atoms exposed to the field.

  11. Towards a subcutaneous optical biosensor based on thermally hydrocarbonised porous silicon.

    PubMed

    Tong, Wing Yin; Sweetman, Martin J; Marzouk, Ezzat R; Fraser, Cara; Kuchel, Tim; Voelcker, Nicolas H

    2016-01-01

    Advanced biosensors in future medicine hinge on the evolvement of biomaterials. Porous silicon (pSi), a generally biodegradable and biocompatible material that can be fabricated to include environment-responsive optical characteristics, is an excellent candidate for in vivo biosensors. However, the feasibility of using this material as a subcutaneously implanted optical biosensor has never been demonstrated. Here, we investigated the stability and biocompatibility of a thermally-hydrocarbonised (THC) pSi optical rugate filter, and demonstrated its optical functionality in vitro and in vivo. We first compared pSi films with different surface chemistries and observed that the material was cytotoxic despite the outstanding stability of the THC pSi films. We then showed that the cytotoxicity correlates with reactive oxygen species levels, which could be mitigated by pre-incubation of THC pSi (PITHC pSi). PITHC pSi facilitates normal cellular phenotypes and is biocompatible in vivo. Importantly, the material also possesses optical properties capable of responding to microenvironmental changes that are readable non-invasively in cell culture and subcutaneous settings. Collectively, we demonstrate, for the first time, that PITHC pSi rugate filters are both biocompatible and optically functional for lab-on-a-chip and subcutaneous biosensing scenarios. We believe that this study will deepen our understanding of cell-pSi interactions and foster the development of implantable biosensors. PMID:26466356

  12. Novel image processing method study for a label-free optical biosensor

    NASA Astrophysics Data System (ADS)

    Yang, Chenhao; Wei, Li'an; Yang, Rusong; Feng, Ying

    2015-10-01

    Optical biosensor is generally divided into labeled type and label-free type, the former mainly contains fluorescence labeled method and radioactive-labeled method, while fluorescence-labeled method is more mature in the application. The mainly image processing methods of fluorescent-labeled biosensor includes smooth filtering, artificial gridding and constant thresholding. Since some fluorescent molecules may influence the biological reaction, label-free methods have been the main developing direction of optical biosensors nowadays. The using of wider field of view and larger angle of incidence light path which could effectively improve the sensitivity of the label-free biosensor also brought more difficulties in image processing, comparing with the fluorescent-labeled biosensor. Otsu's method is widely applied in machine vision, etc, which choose the threshold to minimize the intraclass variance of the thresholded black and white pixels. It's capacity-constrained with the asymmetrical distribution of images as a global threshold segmentation. In order to solve the irregularity of light intensity on the transducer, we improved the algorithm. In this paper, we present a new image processing algorithm based on a reflectance modulation biosensor platform, which mainly comprises the design of sliding normalization algorithm for image rectification and utilizing the improved otsu's method for image segmentation, in order to implement automatic recognition of target areas. Finally we used adaptive gridding method extracting the target parameters for analysis. Those methods could improve the efficiency of image processing, reduce human intervention, enhance the reliability of experiments and laid the foundation for the realization of high throughput of label-free optical biosensors.

  13. Polymer-on-glass waveguide structure for efficient fluorescence-based optical biosensors

    NASA Astrophysics Data System (ADS)

    Bernini, Romeo; Cennamo, Nunzio; Minardo, Aldo; Zeni, Luigi

    2005-03-01

    A novel waveguide geometry for an integrated optics bio-sensor suitable for fluorescence detection is presented. In particular, we propose a polymeric waveguide realized on a glass substrate. This new geometry is aimed to an efficient evanescent-wave excitation of the fluorophores and subsequent collection of the fluorescence emission with no need of optical filters. The absence of any optical filters simplifies the device operation and permits to avoid the losses resulting from the use of the filter itself.

  14. Quartz crystal microbalance (QCM) as biosensor for the detecting of Escherichia coli O157:H7

    NASA Astrophysics Data System (ADS)

    Thanh Ngo, Vo Ke; Giang Nguyen, Dang; Phuong Uyen Nguyen, Hoang; Tran, Van Man; Nguyen, Thi Khoa My; Phat Huynh, Trong; Lam, Quang Vinh; Dat Huynh, Thanh; Truong, Thi Ngoc Lien

    2014-12-01

    Although Escherichia coli (E. coli) is a commensalism organism in the intestine of humans and warm-blooded animals, it can be toxic at higher density and causes diseases, especially the highly toxic E. coli O157:H7. In this paper a quartz crystal microbalance (QCM) biosensor was developed for the detection of E. coli O157:H7 bacteria. The anti-E. coli O157:H7 antibodies were immobilized on a self-assembly monolayer (SAM) modified 5 MHz AT-cut quartz crystal resonator. The SAMs were activated with 16-mercaptopropanoic acid, in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and ester N-hydroxysuccinimide (NHS). The result of changing frequency due to the adsorption of E. coli O157:H7 was measured by the QCM biosensor system designed and fabricated by ICDREC-VNUHCM. This system gave good results in the range of 102-107 CFU mL-1 E. coli O157:H7. The time of bacteria E. coli O157:H7 detection in the sample was about 50 m. Besides, QCM biosensor from SAM method was comparable to protein A method-based piezoelectric immunosensor in terms of the amount of immobilized antibodies and detection sensitivity.

  15. Meeting current public health needs: optical biosensors for pathogen detection and analysis

    NASA Astrophysics Data System (ADS)

    Yang, Minghui; Sapsford, Kim E.; Sergeev, Nikolay; Sun, Steven; Rasooly, Avraham

    2009-02-01

    Pathogen detection and analysis is critical for medicine, food safety, agriculture, public health and biosecurity. Many current microbial detection approaches are based on century-old culturing methods which, while reliable, are slow, provide relatively little information about the pathogens and are not adaptable to high throughput operations. Optical biodetection represents a potential alternative. Most ELISA and chromatography systems are based on optical methods that are also used for analysis of molecular interactions, such as DNA hybridization and protein-protein interactions (e.g. microarrays or SPR biosensors). Various optical biosensor platforms have been developed that have many of the characteristics essential for modern pathogen molecular analysis including sensitivity, speed of analysis, multi-channel capability, relative simplicity and low cost. Here we provide several examples of the use of optical biosensor technology for pathogen detection and analysis including high throughput DNA microarray analysis, SPR-based rapid direct detection of bacterial toxins, CCD-based fluorescent activity analysis of microbial toxins and a simple ECL-based CCD detection system. However, while effective for molecular analysis, most of these technologies are not as sensitive as traditional culturing methods for detecting microorganisms. There is a need to combine optical biosensors with traditional methods to speed culture-based detection and to provide more information regarding the pathogens.

  16. Liquid crystal-based glucose biosensor functionalized with mixed PAA and QP4VP brushes.

    PubMed

    Khan, Mashooq; Park, Soo-Young

    2015-06-15

    4-Cyano-4'-pentylbiphenyl (5CB) in a transmission electron microscopy (TEM) grid was developed for glucose detection by coating with a monolayer of mixed polymer brushes using poly(acrylicacid-b-4-cynobiphenyl-4'-oxyundecylacrylate) (PAA-b-LCP) and quaternized poly(4-vinylpyridine-b-4-cynobiphenyl-4'-oxyundecylacrylate) (QP4VP-b-LCP) (LCP stands for liquid crystal polymer) at the 5CB/aqueous interface. The resultant 5CB in TEM grid was functionalized with the PAA and QP4VP brushes, which were strongly anchored by the LCP block. The PAA brush rendered the 5CB/aqueous interface pH-responsive and the QP4VP brush immobilized glucose oxidase (GOx) through electrostatic interactions without the aid of coupling agents. The glucose was detected through a homeotropic-to-planar orientational transition of the 5CB observed through a polarized optical microscope (POM) under crossed polarizers. The optimum immobilization with a 0.78 µM GOx solution on the dual-brush-coated TEM grid enabled glucose detection at concentrations higher than 0.5 mM with response times shorter than 180 s. This TEM grid glucose sensor provided a linear response of birefringence of the 5CB to glucose concentrations ranging from 0.5 to 11 mM with a Michaelis-Menten constant (Km) of 1.67 mM. This new and sensitive glucose biosensor has the advantages of low production cost, simple enzyme immobilization, high enzyme sensitivity and stability, and easy detection with POM, and may be useful for prescreening the glucose level in the human body. PMID:25617751

  17. Silicon on-chip bandpass filters for the multiplexing of high sensitivity photonic crystal microcavity biosensors

    SciTech Connect

    Yan, Hai Zou, Yi; Yang, Chun-Ju; Chakravarty, Swapnajit; Wang, Zheng; Tang, Naimei; Chen, Ray T.; Fan, Donglei

    2015-03-23

    A method for the dense integration of high sensitivity photonic crystal (PC) waveguide based biosensors is proposed and experimentally demonstrated on a silicon platform. By connecting an additional PC waveguide filter to a PC microcavity sensor in series, a transmission passband is created, containing the resonances of the PC microcavity for sensing purpose. With proper engineering of the passband, multiple high sensitivity PC microcavity sensors can be integrated into microarrays and be interrogated simultaneously between a single input and a single output port. The concept was demonstrated with a 2-channel L55 PC biosensor array containing PC waveguide filters. The experiment showed that the sensors on both channels can be monitored simultaneously from a single output spectrum. Less than 3 dB extra loss for the additional PC waveguide filter is observed.

  18. Development of a penicillin biosensor using a single optical imaging fiber

    NASA Astrophysics Data System (ADS)

    Healey, Brian G.; Walt, David R.

    1995-05-01

    A penicillin biosensor has been fabricated by photodepositing penicillin-sensitive polymer matrices and pH-sensitive polymer matrices on different regions of an optical imaging fiber. Penicillin is detected by coupling the enzymatic activity of penicillinase with the pH sensitivity of fluorescein. Penicillin concentration is correlated to the pH change in the microenvironment of the penicillin-sensitive matrix relative to the pH of the sample solution. This dual sensor removes the need to maintain a constant solution pH when measuring penicillin and should enhance greatly the application of biosensors.

  19. Photosensitive biosensor array system using optical addressing without an addressing circuit on array biochips

    NASA Astrophysics Data System (ADS)

    Ahn, Chang-Geun; Ah, Chil Seong; Kim, Tae-Youb; Park, Chan Woo; Yang, Jong-Heon; Kim, Ansoon; Sung, Gun Yong

    2010-09-01

    This paper introduces a photosensitive biosensor array system with a simple photodiode array that detects photocurrent changes caused by reactions between probe and target molecules. Using optical addressing, the addressing circuit on the array chip is removed for low-cost application, and real cell addressing is achieved using an externally located computer-controllable light-emitting diode array module. The fabricated biosensor array chip shows a good dynamic range of 1-100 ng/mL under prostate-specific antigen detection, with an on-chip resolution of roughly 1 ng/mL.

  20. Optical fiber biosensor based on enzymatic coating matrix for catecholamines assessment in human urine

    NASA Astrophysics Data System (ADS)

    Silva, Lurdes I. B.; Freitas, Ana C.; Rocha-Santos, Teresa A. P.; Pereira, M. E.; Duarte, Armando C.

    2010-09-01

    An optical fiber (OF) biosensor has been developed and applied for simultaneous determination of catecholamines (dopamine, norepinephrine and epinephrine) in human urine. The developed analytical device shows a high potential for catecholamines quantification with a detection limit of 2.1, 2.6 and 3.4 pg mL-1 for dopamine, norepinephrine and epinephrine, respectively. The analytical performance of the OF biosensor was found to be similar to that of the High Performance Liquid Chromatography - Electrochemical Detector (HPLC-ED) regarding catecholamines determination in samples of human urine.

  1. New insights into the molecular mechanisms of biomembrane structural changes and interactions by optical biosensor technology.

    PubMed

    Lee, Tzong-Hsien; Hirst, Daniel J; Aguilar, Marie-Isabel

    2015-09-01

    Biomolecular-membrane interactions play a critical role in the regulation of many important biological processes such as protein trafficking, cellular signalling and ion channel formation. Peptide/protein-membrane interactions can also destabilise and damage the membrane which can lead to cell death. Characterisation of the molecular details of these binding-mediated membrane destabilisation processes is therefore central to understanding cellular events such as antimicrobial action, membrane-mediated amyloid aggregation, and apoptotic protein induced mitochondrial membrane permeabilisation. Optical biosensors have provided a unique approach to characterising membrane interactions allowing quantitation of binding events and new insight into the kinetic mechanism of these interactions. One of the most commonly used optical biosensor technologies is surface plasmon resonance (SPR) and there have been an increasing number of studies reporting the use of this technique for investigating biophysical analysis of membrane-mediated events. More recently, a number of new optical biosensors based on waveguide techniques have been developed, allowing membrane structure changes to be measured simultaneously with mass binding measurements. These techniques include dual polarisation interferometry (DPI), plasmon waveguide resonance spectroscopy (PWR) and optical waveguide light mode spectroscopy (OWLS). These techniques have expanded the application of optical biosensors to allow the analysis of membrane structure changes during peptide and protein binding. This review provides a theoretical and practical overview of the application of biosensor technology with a specific focus on DPI, PWR and OWLS to study biomembrane-mediated events and the mechanism of biomembrane disruption. This article is part of a Special Issue entitled: Lipid-protein interactions. PMID:26009270

  2. Determining Optical Axes of Uniaxial Crystals

    NASA Technical Reports Server (NTRS)

    Schock, H. J.; Regan, C. A.; Lock, J. A.

    1987-01-01

    Polarizing-microscope concept adapted for thick samples. Optical axis of crystal usually found by examining sample thinner than 1 mm between crossed polarizing plates. Frequently impractical to cut off small sample of crystal for testing, technique modified to accommodate large crystals. Ability to circumvent effect of birefringence has applications where laser beams must be transmitted through uniaxial crystals, as in laser diagnostics of contained flows in systems requiring windows for optical access.

  3. A stable and high resolution optical waveguide biosensor based on dense TiO2/Ag multilayer film

    NASA Astrophysics Data System (ADS)

    Jin, Zhao; Guan, Weiming; Liu, Chang; Xue, Tianyu; Wang, Qiyu; Zheng, Weitao; Cui, Xiaoqiang

    2016-07-01

    Optical waveguide (OWG) biosensor has attracted much attention according to the high sensitivity and resolution compared with conventional surface plasmon resonance (SPR) biosensor. Nanoporous materials are usually used as the waveguide layer for absorbing analytes into the porous structure and enhancing the sensor signal. However, this kind of waveguide layer provides poor protection to the metal film and leads to the damage of the biosensor. Ag film can provide great sensitivity in SPR sensing comparing to other metal but was rarely used because of its poor chemical stability. Fabricating high stability Ag based SPR biosensor is still a challenge. In this work we produce an OWG biosensor using a dense TiO2 film as the waveguide layer which provides high resolution and remarkable protection to the metal film. This waveguide structure makes long time detection possible using Ag as the metal layer and is able to lead an enhancement of sensitivity comparing to the Au-based biosensor.

  4. A novel assay for detecting canine parvovirus using a quartz crystal microbalance biosensor.

    PubMed

    Kim, Yong Kwan; Lim, Seong-In; Choi, Sarah; Cho, In-Soo; Park, Eun-Hye; An, Dong-Jun

    2015-07-01

    Rapid and accurate diagnosis is crucial to reduce both the shedding and clinical signs of canine parvovirus (CPV). The quartz crystal microbalance (QCM) is a new tool for measuring frequency changes associated with antigen-antibody interactions. In this study, the QCM biosensor and ProLinker™ B were used to rapidly diagnosis CPV infection. ProLinker™ B enables antibodies to be attached to a gold-coated quartz surface in a regular pattern and in the correct orientation for antigen binding. Receiver operating characteristics (ROC) curves were used to set a cut-off value using reference CPVs (two groups: one CPV-positive and one CPV-negative). The ROC curves overlapped and the point of intersection was used as the cut-off value. A QCM biosensor with a cut-off value of -205 Hz showed 95.4% (104/109) sensitivity and 98.0% (149/152) specificity when used to test 261 field fecal samples compared to PCR. In conclusion, the QCM biosensor described herein is eminently suitable for the rapid diagnosis of CPV infection with high sensitivity and specificity. Therefore, it is a promising analytical tool that will be useful for clinical diagnosis, which requires rapid and reliable analyses. PMID:25813597

  5. Optical waveguide biosensor based on cascaded Mach-Zehnder interferometer and ring resonator with Vernier effect

    NASA Astrophysics Data System (ADS)

    Jiang, Xianxin; Tang, Longhua; Song, Jinyan; Li, Mingyu; He, Jian-Jun

    2014-03-01

    Optical waveguide biosensors based on silicon-on-insulator (SOI) have been extensively investigated owing to its various advantages and many potential applications. In this article, we demonstrate a novel highly sensitive biosensor based on cascaded Mach-Zehnder interferometer (MZI) and ring resonator with the Vernier effect using wavelength interrogation. The experimental results show that the sensitivity reached 1,960 nm/RIU and 19,100 nm/RIU for sensors based on MZI alone and cascaded MZI-ring with Vernier effect, respectively. A biosensing application was also demonstrated by monitoring the interaction between goat and antigoat immunoglobulin G (IgG) pairs. This integrated high sensitivity biosensor has great potential for medical diagnostic applications.

  6. Electrogenerated chemiluminescence of luminol for oxidase-based fibre-optic biosensors.

    PubMed

    Marquette, C A; Leca, B D; Blum, L J

    2001-01-01

    The luminol electrochemiluminescence has been exploited for the development of several fibre-optic biosensors allowing the detection of hydrogen peroxide and of substrates of H(2)O(2)-producing oxidases. Electro-optical flow injection analysis of glucose, lactate, cholesterol and choline are thus described. To perform the experiments, a glassy carbon electrode was polarized at a fixed potential. Luminol was then electrochemically oxidized and could react in the presence of hydrogen peroxide to produce light. Several parameters had to be optimized to obtain reliable optical biosensors. An optimum applied potential of +425 mV between the glassy carbon electrode and the platinum pseudo-reference electrode was determined, allowing the best signal: noise ratio to be obtained. It was also necessary to optimize the experimental conditions for the immobilization of the different oxidases involved (preactivated membranes, chemically activated collagen membranes, photopolymerized matrix). For each biosensor developed, the optimum reaction conditions have been studied: buffer composition, pH, temperature, flow rate and luminol concentration. Under optimal conditions, the detection limits (S/N = 3) were 30 pmol, 60 pmol, 0.6 nmol and 10 pmol for lactate, glucose, cholesterol and choline, respectively. The miniaturization of electrochemiluminescence-based biosensors has been realized using screen-printed electrodes instead of a glassy carbon macroelectrode, with choline oxidase as a model H(2)O(2)-generating oxidase. PMID:11312542

  7. pH-based fiber optic biosensors for use in clinical and biotechnological applications

    NASA Astrophysics Data System (ADS)

    Mueller, Cord; Hitzmann, Bernd; Schubert, Florian; Scheper, Thomas

    1995-05-01

    The development of pH-based fiber optic biosensors and their uses in clinical and biotechnological applications are described. Based on a pH-sensitive optode, different biosensors for urea, penicillin, glucose and creatinine were developed. A multichannel modular fluorimeter was used to measure signals from up to three optodes simultaneously. The pH value and the buffer capacity are critical factors for biosensors based on pH probes and influence the biosensor signal. A flow injection analysis (FIA) system is used to eliminate the latter influences. With this integrated system, samples can be analyzed sequentially by the injection of a defined volume of each sample into a continuously flowing buffer stream that transports the samples to the sensors. The complex signal is transformed and analyzed by a computer system. Characteristic features of the FIA peak give information about the buffer capacity in the solution. With the help of intelligent computing (neural networks) it is possible to recognize these features and relate them to the respective buffer capacity to obtain more accurate values. Various applications of these biosensors are discussed. The pH optode is also used to monitor enzymatic reactions in non aqueous solvents. In this case the production of acetic acid can be detected on line.

  8. Design optimization of structural parameters for highly sensitive photonic crystal label-free biosensors.

    PubMed

    Ju, Jonghyun; Han, Yun-ah; Kim, Seok-min

    2013-01-01

    The effects of structural design parameters on the performance of nano-replicated photonic crystal (PC) label-free biosensors were examined by the analysis of simulated reflection spectra of PC structures. The grating pitch, duty, scaled grating height and scaled TiO2 layer thickness were selected as the design factors to optimize the PC structure. The peak wavelength value (PWV), full width at half maximum of the peak, figure of merit for the bulk and surface sensitivities, and surface/bulk sensitivity ratio were also selected as the responses to optimize the PC label-free biosensor performance. A parametric study showed that the grating pitch was the dominant factor for PWV, and that it had low interaction effects with other scaled design factors. Therefore, we can isolate the effect of grating pitch using scaled design factors. For the design of PC-label free biosensor, one should consider that: (1) the PWV can be measured by the reflection peak measurement instruments, (2) the grating pitch and duty can be manufactured using conventional lithography systems, and (3) the optimum design is less sensitive to the grating height and TiO2 layer thickness variations in the fabrication process. In this paper, we suggested a design guide for highly sensitive PC biosensor in which one select the grating pitch and duty based on the limitations of the lithography and measurement system, and conduct a multi objective optimization of the grating height and TiO2 layer thickness for maximizing performance and minimizing the influence of parameter variation. Through multi-objective optimization of a PC structure with a fixed grating height of 550 nm and a duty of 50%, we obtained a surface FOM of 66.18 RIU-1 and an S/B ratio of 34.8%, with a grating height of 117 nm and TiO2 height of 210 nm. PMID:23470487

  9. Experimental demonstration of a Fresnel-reflection based optical fiber biosensor coated with polyelectrolyte multilayers

    NASA Astrophysics Data System (ADS)

    Yu, Wenjie; Lang, Tingting

    2014-11-01

    We report that the end facet of an optical fiber can be coated with polyelectrolyte multilayers (PEM) of polycation (diallyldimethyl ammonium chloride) and polyanion (styrenesulfonate sodium salt) (PDDA+PSS)n (n is the number of bilayers), which functions effectively as a Fresnel-reflection based biosensor. The experimental setup includes a broadband light source, a 3dB coupler, and an optical spectrum analyzer. Biotin and streptavidin are deposited onto the multilayers-coated end facet sequentially. The light intensity change due to variation of external refractive index is monitored. When the concentrations of streptavidin changes from 0.1mg/ml to 1mg/ml, a linear relationship between the concentration of streptavidin and the reflected optical power at the wavelength of 1530nm is observed. The sensitivity increases from -1.6262×10-3 dB/ppm to -4.7852 ×10-3 dB/ppm, when the number of PEM increases from 1 to 2. Then we confirm the optimized numbers of bilayers of PEM are 5 through experiment. Selectivity and repeatability of our proposed optical fiber biosensor are verified. When bovine serum albumin (BSA) is added instead of streptavidin, the obtained spectra overlaps with that of biotin's. The final end facet coated with PEM and biotin-streptavidin can be cleaned using microwave vibration or aqua regia. The microwave vibration method is utilized due to security concern. The optical spectra changes back to the initial one of the optical fiber in air. In conclusion, a Fresnel-reflection based optical fiber biosensor with good sensitivity, selectivity and repeatability is proposed. This biosensor has the advantages of simple structure, low cost and reliability.

  10. Label-free detection of glycated haemoglobin in human blood using silicon-based photonic crystal nanocavity biosensor

    NASA Astrophysics Data System (ADS)

    Olyaee, Saeed; Seifouri, Mahmood; Mohsenirad, Hamideh

    2016-07-01

    In this paper, we describe a two-dimensional photonic crystal-based biosensor that consists of a waveguide and a nanocavity with high sensitivity. A new method is employed for increasing sensitivity of the biosensor. The simulation results show that biosensor is highly sensitive to the refractive index (RI) variations due to injected biomaterials, like glycated haemoglobin, into the sensing surface. The proposed biosensor is designed for the wavelength range of 1514.4-1896.3 nm. The sensitivity and the quality factor are calculated to be 3000 and 272.43 nm/RIU, respectively. The designed structure can detect a 0.002 change in the RI via resonant wavelength shift of 0.9 nm. The band diagram and transmission spectra are computed using plane wave expansion and finite difference time domain methods.

  11. Hollow core photonic crystal fiber as a robust Raman biosensor

    NASA Astrophysics Data System (ADS)

    Khetani, Altaf; Momenpour T. Monfared, Ali; Tiwari, Vidhu S.; Anis, Hanan; Riordon, Jason; Godin, Michel

    2013-03-01

    The present work demonstrates the integration of hollow core photonic crystal fibers (HC-PCF), microfluidics, and statistical analysis for monitoring biomolecules using Raman spectroscopy. HC-PCF as a signal enhancer has been proven by many researchers. However, there have been challenges in using HC-PCF for practical applications due to limitations such as coupling, stability, evaporation, clogging, consistent filling, and reusing the same fiber. This limited the potential of HC-PCF to detect low concentrations of liquid samples, which is why HC-PCF still hasn't transcended the lab barriers. The current device is based on an H-design lay-out which uses the pressure difference between the two ends of the fiber for filling and flushing the liquid samples. This mitigated several issues related to device performance by allowing us to fill the fiber with liquid samples consistently, rapidly and reproducibly. The resulting Raman signals were significantly more stable as various concentrations of ethanol in water were sequentially introduced into the fiber. The scheme also allowed us to overcome the barrier of predicting low concentrations by applying Partial Least Square (PLS) technique which was done for the first time using HC-PCF. Thus, the present scheme paves path for the inclusion of HC-PCF in the main stream point-of-care technology.

  12. Glucose biosensor based on GOx/HRP bienzyme at liquid-crystal/aqueous interface.

    PubMed

    Khan, Mashooq; Park, Soo-Young

    2015-11-01

    Glucose oxidase (GOx) and horseradish peroxidase (HRP) were co-immobilized to the polyacrylicacid block of a poly(acrylicacid-b-4-cyanobiphenyl-4'-undecylacrylate) (PAA-b-LCP) copolymer in water. PAA-b-LCP was strongly anchored by the LCP block in 4-cyano-4'-pentylbiphenyl (5CB) which was contained in a transmission electron microscope (TEM) grid for glucose detection. The optimal conditions for the performance of the TEM grid glucose biosensor were studied in terms of the activity and stability of the immobilized enzymes. Glucose in water was detected by the 5CB changing from a planar to a homeotropic orientation, as observed through a polarized optical microscope. The TEM biosensor detected glucose concentrations at ⩾0.02 mM, with an optimal GOx/HRP molar ratio of 3/1. This glucose biosensor has characteristics of enzyme sensitivity and stability, reusability, the ease and selective glucose detection which may provide a new way of detecting glucose. PMID:26196711

  13. Quartz crystal microbalance biosensor for rapid detection of aerosolized microorganisms

    NASA Astrophysics Data System (ADS)

    Farka, Zdenĕk.; Kovár, David; Skládal, Petr

    2015-05-01

    Biological warfare agents (BWAs) represent the current menace of the asymmetric war. The early detection of BWAs, especially in the form of bioaerosol, is a challenging task for governments all around the world. Label-free quartz crystal microbalance (QCM) immunosensor and electrochemical immunosensor were developed and tested for rapid detection of BWA surrogate (E. coli) in the form of bioaerosol. Two immobilization strategies for the attachment of antibody were tested; the gold sensor surface was activated by cysteamine and then antibody was covalently linked either using glutaraldehyde, or the reduced antibodies were attached via Sulfo-SMCC. A portable bioaerosol chamber was constructed and used for safe manipulation with aerosolized microorganisms. The dissemination was done using a piezoelectric humidifier, distribution of bioaerosol inside the chamber was ensured using three 12-cm fans. The whole system was controlled remotely using LAN network. The disseminated microbial cells were collected and preconcentrated using the wetted-wall cyclone SASS 2300, the analysis was done using the on-line linked immunosensors. The QCM immunosensor had limit of detection 1×104 CFU·L-1 of air with analysis time 16 min, the whole experiment including dissemination and sensor surface regeneration took 40 min. In case of blank (disseminated sterile buffer), no signal change was observed. The electrochemical immunosensor was able to detect 150 CFU·L-1 of air in 20 min; also in this case, no interferences were observed. Reference measurements were done using particle counter Met One 3400 and by cultivation method on agar plates. The sensors have proved to be applicable for rapid screening of microorganisms in air.

  14. Optical isopropanol biosensor using NADH-dependent secondary alcohol dehydrogenase (S-ADH).

    PubMed

    Chien, Po-Jen; Ye, Ming; Suzuki, Takuma; Toma, Koji; Arakawa, Takahiro; Iwasaki, Yasuhiko; Mitsubayashi, Kohji

    2016-10-01

    Isopropanol (IPA) is an important solvent used in industrial activity often found in hospitals as antiseptic alcohol rub. Also, IPA may have the potential to be a biomarker of diabetic ketoacidosis. In this study, an optical biosensor using NADH-dependent secondary alcohol dehydrogenase (S-ADH) for IPA measurement was constructed and evaluated. An ultraviolet light emitting diode (UV-LED, λ=340nm) was employed as the excitation light to excite nicotinamide adenine dinucleotide (NADH). A photomultiplier tube (PMT) was connected to a two-way branch optical fiber for measuring the fluorescence emitted from the NADH. S-ADH was immobilized on the membrane to catalyze IPA to acetone and reduce NAD(+) to be NADH. This IPA biosensor shows highly sensitivity and selectivity, the calibration range is from 500 nmol L(-1) to 1mmolL(-1). The optimization of buffer pH, temperature, and the enzyme-immobilized method were also evaluated. The detection of IPA in nail related cosmetic using our IPA biosensor was also carried out. The results showed that large amounts of IPA were used in these kinds of cosmetics. This IPA biosensor comes with the advantages of rapid reaction, good reproducibility, and wide dynamic range, and is also expected to use for clinical IPA detections in serum or other medical and health related applications. PMID:27474326

  15. Bifurcating optical pattern recognition in photorefractive crystals

    NASA Technical Reports Server (NTRS)

    Liu, Hua-Kuang

    1993-01-01

    A new concept and experimental demonstration of a bifurcating optical pattern recognizer that uses a nonlinear gain saturation memory medium such as a high-gain photorefractive crystal are presented. A barium titanate crystal is used as a typical example of the nonlinear medium for the demonstration of the bifurcating optical pattern recognizer.

  16. A novel antibody immobilization strategy for optical biosensors

    NASA Astrophysics Data System (ADS)

    Lifson, Mark A.; Carter, Jared A.; Miller, Benjamin L.

    2014-03-01

    Arrayed Imaging Reflectometry (AIR) is a highly sensitive label-free biosensor which can be used to detect hundreds of antigens on a single substrate. The signal monitored with AIR is the light intensity of an angled beam reflected off of a flat substrate which is composed of a protein-reactive film on a thermally grown silicon oxide layer. If the angle, wavelength, and polarization of the incident light beam is fixed, a near-zero reflectance condition can be obtained by adjusting the thickness of the thermally grown oxide. In a typical AIR biosensing experiment, antibodies are printed (using a piezoelectric microarrayer) on top of the oxide layer to create a minimum reflectance condition. If the substrate is exposed to a complex solution (such as serum), the patterned antibodies bind to their specific targets increasing the effective spot thickness, which perturbs the anti-reflective condition and causes a measurable signal increase. One of the main considerations with AIR is evaluating and controlling the bioactivity and efficiency of antibody immobilization after printing, since these factors significantly affect the dynamic range and limit of detection. Here, we present preliminary experiments towards using microgel nanoparticles as a simple and customizable construct to deposit antibodies on biosensor surfaces. This method can be generalized to work with other microarray technology formats, including those that are not label-free.

  17. Optical temperature sensor utilizing birefringent crystals

    NASA Technical Reports Server (NTRS)

    Quick, William H. (Inventor); James, Kenneth A. (Inventor); Strahan, Virgil H. (Inventor)

    1980-01-01

    A temperature sensor comprising an optical transducer member having an array of birefringent crystals. The length and, accordingly, the sensitivity to temperature change of successive birefringent crystals varies according to a particular relationship. The transducer is interconnected with a fiber optic transmission and detecting system. Respective optical output signals that are transmitted from the birefringent crystals via the fiber optic transmission system are detected and decoded so as to correspond to digits of a numbering system, whereby an accurate digital representation of temperature can ultimately be provided.

  18. Optical Fiber LSPR Biosensor Prepared by Gold Nanoparticle Assembly on Polyelectrolyte Multilayer

    PubMed Central

    Shao, Yunliang; Xu, Shuping; Zheng, Xianliang; Wang, Ye; Xu, Weiqing

    2010-01-01

    This article provides a novel method of constructing an optical fiber localized surface plasmon resonance (LSPR) biosensor. A gold nanoparticle (NP) assembled film as the sensing layer was built on the polyelectrolyte (PE) multilayer modified sidewall of an unclad optical fiber. By using a trilayer PE structure, we obtained a monodisperse gold NP assembled film. The preparation procedure for this LSPR sensor is simple and time saving. The optical fiber LSPR sensor has higher sensitivity and outstanding reproducibility. The higher anti-interference ability for response to an antibody makes it a promising method in application as a portable immuno-sensor. PMID:22319313

  19. Fibre-optic biosensor based on luminescence and immobilized enzymes: microdetermination of sorbitol, ethanol and oxaloacetate.

    PubMed

    Gautier, S M; Blum, L J; Coulet, P R

    1990-01-01

    We have investigated highly selective and ultrasensitive biosensors based on luminescent enzyme systems linked to optical transducers. A fibre-optic sensor with immobilized enzymes was designed; the solid-phase bioreagent was maintained in close contact contact with the tip of a glass fibre bundle connected to the photomultiplier tube of a luminometer. A bacterial luminescence fibre-optic sensor was used for the microdetermination of NADH. Various NAD(P)-dependent enzymes, sorbitol dehydrogenase, alcohol dehydrogenase and malate dehydrogenase, were co-immobilized on preactivated polyamide membranes with the bacterial system and used for the microdetermination of sorbitol, ethanol and oxaloacetate at the nanomolar level with a good precision. PMID:2316395

  20. Optical vortex arrays from smectic liquid crystals.

    PubMed

    Son, Baeksik; Kim, Sejeong; Kim, Yun Ho; Käläntär, K; Kim, Hwi-Min; Jeong, Hyeon-Su; Choi, Siyoung Q; Shin, Jonghwa; Jung, Hee-Tae; Lee, Yong-Hee

    2014-02-24

    We demonstrate large-area, closely-packed optical vortex arrays using self-assembled defects in smectic liquid crystals. Self-assembled smectic liquid crystals in a three-dimensional torus structure are called focal conic domains. Each FCD, having a micro-scale feature size, produces an optical vortex with consistent topological charge of 2. The spiral profile in the interferometry confirms the formation of an optical vortex, which is predicted by Jones matrix calculations. PMID:24663788

  1. A novel FRET-based optical fiber biosensor for rapid detection of Salmonella typhimurium.

    PubMed

    Ko, Sungho; Grant, Sheila A

    2006-01-15

    A biosensor that is portable and permits on-site analysis of samples would significantly reduce the large economical burden of food products recalls. A fiber optic portable biosensor utilizing the principle of fluorescence resonance energy transfer (FRET) was developed for fast detection of Salmonella typhimurium (S. typhimurium) in ground pork samples. Labeled antibody-protein G complexes were formed via the incubation of anti-Salmonella antibodies labeled with FRET donor fluorophores (Alexa Fluor 546) and protein G (PG) labeled with FRET acceptor fluorophores (Alexa Fluor 594). Utilizing silanization, the labeled antibodies-PG complexes were then immobilized on decladded, tapered silica fiber cores to form the evanescent wave-sensing region. The biosensors were tested in two different solutions: (1) PBS doped with S. typhimurium and (2) homogenized pork sample with S. typhimurium. The fiber probes tested in a S. typhimurium doped phosphate buffered solution demonstrated the feasibility of the biosensor for detecting S. typhimurium as well as determined the optimal packing density of the labeled antibody-PG complexes on the surface of fibers. The results showed that a packing density of 0.033 mg/ml produced the lowest limit of detection of 10(3)cells/ml with 8.2% change in fluorescence. The fiber probes placed in homogenized pork samples inoculated with S. typhimurium showed a limit of detection of 10(5)CFU/g with a 6.67% in fluorescence within a 5-min response time. These results showed that the FRET-based fiber optic biosensor can become a useful analytical tool for detection of S. typhimurium in real food samples. PMID:16040238

  2. Liquid crystals for optical non-display applications

    NASA Astrophysics Data System (ADS)

    Lavrentovich, Oleg D.

    2012-10-01

    Liquid crystals (LCs) demonstrate a number of unusual physical properties and effects that so far has been explored mainly for LC display (LCD) applications. This presentation discusses aspects of LCs that lead to the new opportunities in non-LCD applications, such as biosensors, micro- and opto-fluidics, switchable metamaterials. A LC is a unique medium for colloidal particles as it responds to the presence of inclusions by altering the orientation of LC molecules and thus the optic axis. The effect can be used in real-time sensing of microbes, as the molecular reorientation is easily detectable by optical means. Symmetry breaking associated with director distortions around inclusions in LCs enables a new mechanism of nonlinear electrophoresis. In the liquid-crystal enabled electrophoresis (LCEEP), the velocity of particle grows with the square of the applied field. The feature allows one to use an AC driving, to create steady flows and to move uncharged particle. The trajectory of particle is not necessarily parallel to the electric field and can be controlled by the director configuration. A gradient electric field can be used to align metallic nanorods into ordered LC-like birefringent structures with spatially varying refractive index; the latter represents a switchable medium for transformation optics.

  3. Towards a biosensor based on anti resonant reflecting optical waveguide fabricated from porous silicon.

    PubMed

    Hiraoui, M; Haji, L; Guendouz, M; Lorrain, N; Moadhen, A; Oueslati, M

    2012-01-01

    Recently, we demonstrated that Anti Resonant Reflecting Optical Waveguide (ARROW) based on porous silicon (PS) material can be used as a transducer for the development of a new optical biosensor. Compared to a conventional biosensor waveguide based on evanescent waves, the ARROW structure is designed to allow a better overlap between the propagated optical field and the molecules infiltrated in the porous core layer and so to provide better molecular interactions sensitivity. The aim of this work is to investigate the operating mode of an optical biosensor using the ARROW structure. We reported here an extensive study where the antiresonance conditions were adjusted just before the grafting of the studied molecules for a given refractive index range. The interesting feature of the studied ARROW structure is that it is elaborated from the same material which is the porous silicon obtained via a single electrochemical anodization process. After oxidation and preparation of the inner surface of porous silicon by a chemical functionalization process, bovine serum albumin (BSA) molecules, were attached essentially in the upper layer. Simulation study indicates that the proposed sensor works at the refractive index values ranging from 1.3560 to 1.3655. The experimental optical detection of the biomolecules was obtained through the modification of the propagated optical field and losses. The results indicated that the optical attenuation decreases after biomolecules attachment, corresponding to a refractive index change Δn(c) of the core. This reduction was of about 2 dB/cm and 3 dB/cm for Transverse Electric (TE) and Transverse Magnetic (TM) polarizations respectively. Moreover, at the detection step, the optical field was almost located inside the core layer. This result was in good agreement with the simulated near field profiles. PMID:22560108

  4. Use of liposomal amplifiers in total internal reflection fluorescence fiber-optic biosensors for protein detection.

    PubMed

    Chang, Ying-Feng; Fu, Chen; Chen, Yi-Ting; Fang-Ju Jou, Amily; Chen, Chii-Chang; Chou, Chien; Annie Ho, Ja-An

    2016-03-15

    Evanescent-wave excited fluorescence technology has been demonstrated to enhance sensitivity and reduce matrix effects, making it suitable for biosensor development. In this study, we developed a liposome-based, total internal reflection fluorescence, fiber-optic biosensor (TIRF-FOB) for protein detection, which integrates a liposomal amplifier and sandwich immunoassay format with TIRF-FOB. In addition, the antibody-tagged and fluorophore-entrapped liposomes for heterogeneous detection of target molecules were designed and synthesized. This biosensor successfully detected the target protein (model analyzed here is IgG) with a limit of detection (LOD) of 2.0 attomoles for the target protein (equivalent to 2.0 pg/mL of protein presented in 150 μL of sample solution). The features of this ultra-sensitive liposomal TIRF-FOB are (i) fluorescence is excited via evanescent waves and amplified via liposomes; (ii) the use of two polyclonal antibodies in the sandwich assay format increases the specificity and lowers the cost of our assay. Based on the exceptional detection sensitivity and cost-effectiveness, we believe that the proposed biosensor has great potential as a practical, clinical diagnostic tool in the near future. PMID:26595485

  5. Photonic crystal biosensor microplates with integrated fluid networks for high throughput applications in drug discovery

    NASA Astrophysics Data System (ADS)

    Choi, Charles J.; Chan, Leo L.; Pineda, Maria F.; Cunningham, Brian T.

    2007-09-01

    Assays used in pharmaceutical research require a system that can not only detect biochemical interactions with high sensitivity, but that can also perform many measurements in parallel while consuming low volumes of reagents. While nearly all label-free biosensor transducers to date have been interfaced with a flow channel, the liquid handling system is typically aligned and bonded to the transducer for supplying analytes to only a few sensors in parallel. In this presentation, we describe a fabrication approach for photonic crystal biosensors that utilizes nanoreplica molding to produce a network of sensors that are automatically self-aligned with a microfluidic network in a single process step. The sensor/fluid network is inexpensively produced on large surface areas upon flexible plastic substrates, allowing the device to be incorporated into standard format 96-well microplates. A simple flow scheme using hydrostatic pressure applied through a single control point enables immobilization of capture ligands upon a large number of sensors with 220 nL of reagent, and subsequent exposure of the sensors to test samples. A high resolution imaging detection instrument is capable of monitoring the binding within parallel channels at rates compatible with determining kinetic binding constants between the immobilized ligands and the analytes. The first implementation of this system is capable of monitoring the kinetic interactions of 11 flow channels at once, and a total of 88 channels within an integrated biosensor microplate in rapid succession. The system was initially tested to characterize the interaction between sets of proteins with known binding behavior.

  6. Evaluation of optical excitation conditions for ruthenium complex for biosensor optodes

    NASA Astrophysics Data System (ADS)

    Pieper, Sean; Zhong, Zhong; Lear, Kevin L.; Reardon, Ken

    2007-03-01

    Development of a fiber optic biosensor incorporating genetically engineered enzymes which catalyze chlorinated ethenes in an oxygen-consuming reaction for in situ monitoring of groundwater contaminants motivates optimization of optode excitation conditions. These conditions affect the sensitivity, signal-to-noise, and optode service life impacting the quality of the overall biosensor. Optodes are generally comprised of a fluorophore conjugated with a polymer as a substrate cross linked at the distal end of a fiber optic. We investigate the excitation conditions of tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) chloride (Ru(dpp)3) conjugated with poly(vinyl alcohol) (PVOH) as an optode. A reported advantage of Ru(dpp)3 is that it has no emission spectral shift occurring under varying chemical and environmental conditions. Photostability degradation due to photobleaching of Ru(dpp)3 with PVOH as a substrate is explored by varying the optical irradiance of the fluorophore containing optode. Other issues relating to practical implementation of Ru(dpp)3 as oxygen sensitive biosensors will be discussed.

  7. On-site detection of explosives in groundwater with a fiber optic biosensor

    SciTech Connect

    Van Bergen, S.K.; Bakaltcheva, I.B.; Lundgren, J.S.; Shriver-Lake, L.C.

    2000-02-15

    Two primary explosives involved in groundwater contamination, 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), were detected on-site at low ppb levels with a semiautomated fiber optic biosensor. Validation of the Analyte 2000 for TNT and RDX detection was performed at two Superfund sites, Umatilla Army Depot and Naval Surface Weapons Center Crane. Samples from monitoring wells were split for analysis using the fiber optic biosensor on-site and using US EPA SW-846 Method 8330 (reverse-phase high performance liquid chromatography) in an offsite laboratory. The Analyte 2000, a multifiber probe fluorimeter, was coupled to a fluidics unit for semiautomated operation. The fiber optic biosensor assay is based on a competitive fluorescent immunoassay performed on the silica core of a fiber probe. From these studies, the limit of detection was determined to be 5 {mu}g/L for both TNT and RDX. In addition to the field samples, extensive laboratory analyses were performed to determine cross-reactivity, matrix effects, and false positive/negative rates.

  8. Biosensor for direct determination of organophosphate nerve agents using recombinant Escherichia coli with surface-expressed organophosphorus hydrolase. 2. Fiber-optic microbial biosensor.

    PubMed

    Mulchandani, A; Kaneva, I; Chen, W

    1998-12-01

    A fiber-optic microbial biosensor suitable for direct measurement of organophosphate nerve agents was developed. The unique features of this novel microbial biosensor were the recombinant Escherichia coli cells expressing the enzyme organophosphorus hydrolase on the cell surface and the optical detection of the products of enzyme-catalyzed organophosphate hydrolysis. The use of cells with the metabolic enzyme expressed on the cell surface as a biological sensing element provides advantages of no resistance to mass transport of the analyte and product across the cell membrane and low cost due to elimination of enzyme purification, over the conventional microbial biosensors based on cells expressing enzyme intracellularly and enzyme-based sensors, respectively. The use of an optical transducer allows the detection of different organophosphates in a mixture, presently not feasible with acetylcholinesterase-based biosensors. E. coli cells expressing organophosphorus hydrolase (OPH) on the cell surface were immobilized in low melting temperature agarose on a nylon membrane and attached to the common end of a bifurcated fiber-optic bundle. OPH-expressing E. coli cells catalyzed the hydrolysis of organophosphorus pesticides to form stoichiometric amounts of chromophoric products that absorb light at specific wavelengths. The backscattered radiation of the specific wavelength incident light was measured using a photomultiplier detector and correlated to the organophosphate concentration. The best sensitivity and response time were obtained using a sensor constructed with 1.5 mg of cells operating in pH 9, 50 mM HEPES buffer with 100 mM NaCl and 0.05 mM CoCl2 at 30 degrees C. At optimized conditions, the biosensor measured paraoxon, parathion, and coumaphos pesticides with high selectivity against triazine and carbamate pesticides in approximately 10 min. The lower detection limits were 3 microM for paraoxon and parathion and 5 microM for coumaphos. When stored in the

  9. Crystal optical studies of lithium tetraborate

    NASA Astrophysics Data System (ADS)

    Kushnir, O. S.; Burak, Y. V.; Bevz, O. A.; Polovinko, I. I.

    1999-10-01

    Using the HAUP-type universal polarimeter and the Senarmont technique, detailed crystal optical studies of Li2B4O7, lithium tetraborate, are carried out. It is shown that the optical indicatrix rotation and the optical activity are absent from the crystal, in accordance with symmetry considerations. Measurements of optical birefringence reveal the existence of a regular staircase-like temperature behaviour in the whole range under investigation (290-480 K), a hysteresis character of the birefringence under cycling temperature and a pronounced thermooptical memory effect. The origins of the above phenomena are analysed, in particular the possible influence of the pyroelectric effect and systematic errors of the optical equipment. A conclusion is drawn that the main features of the birefringence are well explained by an incommensurately modulated super-structure which is at present a matter of debate. The peculiarities of the optical properties of lithium tetraborate are compared with those of incommensurate crystals known from the literature.

  10. Optical logic gates employing liquid crystal optical switches.

    PubMed

    Khan, A H; Nejib, U R

    1987-01-15

    This paper describes very simple optical logic gates consisting of liquid crystal optical switches. This technique was used to implement all possible 2-operand Boolean functions. The importance of these systems in making optical computers is discussed in terms of a binary half-adder and a flip-flop. A new algebra governing the function of these systems is also proposed. PMID:20454123

  11. Optical Diagnostics of Solution Crystal Growth

    NASA Technical Reports Server (NTRS)

    Kim, Yongkee; Reddy, B. R.; George, T. G.; Lal, R. B.

    1996-01-01

    Non-contact optical techniques such as, optical heterodyne, ellipsometry and interferometry, for real time in-situ monitoring of solution crystal growth are demonstrated. Optical heterodyne technique has the capability of measuring the growth rate as small as 1A/sec. In a typical Michelson interferometer set up, the crystal is illuminated by a Zeeman laser with frequency omega(sub 1) and the reference beam with frequency omega(sub 2). As the crystal grows, the phase of the rf signal changes with respect to the reference beam and this phase change is related to the crystal growth rate. This technique is demonstrated with two examples: (1) by measuring the copper tip expansion/shrinkage rate and (2) by measuring the crystal growth rate of L-Arginine Phosphate (LAP). The first test shows that the expansion/shrinkage rate of copper tip was fast in the beginning, and gets slower as the expansion begins to stabilize with time. In crystal growth, the phase change due the crystal growth is measured using a phase meter and a strip chart recorder. Our experimental results indicate a varied growth rate from 69.4 to 92.6A per sec. The ellipsometer is used to study the crystal growth interface. From these measurements and a theoretical modeling of the interface, the various optical parameters can be deduced. Interferometry can also be used to measure the growth rate and concentration gradient in the vicinity of the crystal.

  12. Piezoelectric Mass-Sensing Devices as Biosensors-An Alternative to Optical Biosensors?

    PubMed

    Janshoff; Galla; Steinem

    2000-11-17

    In the early days of electronic communication-as a result of the limited number of quartz resonators available-frequency adjustment was accomplished by a pencil mark depositing a foreign mass layer on the crystal. In 1959, Sauerbrey showed that the shift in resonance frequency of thickness-shear-mode resonators is proportional to the deposited mass. This was the starting point for the development of a new generation of piezoelectric mass-sensitive devices. However, it was the development of new powerful oscillator circuits that were capable of operating thickness shear mode resonators in fluids that enabled this technique to be introduced into bioanalytic applications. In the last decade adsorption of biomolecules on functionalized surfaces turned in to one of the paramount applications of piezoelectric transducers. These applications include the study of the interaction of DNA and RNA with complementary strands, specific recognition of protein ligands by immobilized receptors, the detection of virus capsids, bacteria, mammalian cells, and last but not least the development of complete immunosensors. Piezoelectric transducers allow a label-free detection of molecules; they are more than mere mass sensors since the sensor response is also influenced by interfacial phenomena, viscoelastic properties of the adhered biomaterial, surface charges of adsorbed molecules, and surface roughness. These new insights have recently been used to investigate the adhesion of cells, liposomes, and proteins onto surfaces, thus allowing the determination of the morphological changes of cells as a response to pharmacological substances and changes in the water content of biopolymers without employing labor-intense techniques. However, the future will show whether the quartz-crystal microbalance will assert itself against established label-free sensor devices such as surface plasmon resonance spectroscopy and interferometry. PMID:11093194

  13. Amplification of the Signal Intensity of Fluorescence-Based Fiber-Optic Biosensors Using a Fabry-Perot Resonator Structure

    PubMed Central

    Hsieh, Meng-Chang; Chiu, Yi-Hsin; Lin, Sheng-Fu; Chang, Jenq-Yang; Chang, Chia-Ou; Chiang, Huihua Kenny

    2015-01-01

    Fluorescent biosensors have been widely used in biomedical applications. To amplify the intensity of fluorescence signals, this study developed a novel structure for an evanescent wave fiber-optic biosensor by using a Fabry-Perot resonator structure. An excitation light was coupled into the optical fiber through a laser-drilled hole on the proximal end of the resonator. After entering the resonator, the excitation light was reflected back and forth inside the resonator, thereby amplifying the intensity of the light in the fiber. Subsequently, the light was used to excite the fluorescent molecules in the reactive region of the sensor. The experimental results showed that the biosensor signal was amplified eight-fold when the resonator reflector was formed using a 92% reflective coating. Furthermore, in a simulation, the biosensor signal could be amplified 20-fold by using a 99% reflector. PMID:25690548

  14. Surface plasmon resonance biosensor based on large size square-lattice photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Bing, Pibin; Li, Zhongyang; Yuan, Sheng; Yao, Jianquan; Lu, Ying

    2016-04-01

    A surface plasmon resonance biosensor based on large size square-lattice photonic crystal fiber has been designed and simulated by finite element method. The square-lattice airholes are first coated with a calcium fluoride layer to provide mode confinement, then a nanoscale gold layer is deposited to excite the plasmon mode, and finally, the sample is infiltrated into the holes. The numerical results reveal that the resonance properties are easily affected by many parameters. The refractive index resolution of corresponding sensor can reach 4.3 × 10-6 RIU when the optimum parameters are set as the radius of curvature of the airhole r = 2 μm, the thickness of the core struts c = 200 nm, the auxiliary dielectric layer s = 1 μm, and the gold film d = 40 nm. In addition, the effective area and nonlinear coefficient are calculated.

  15. Magneto-optic garnet and liquid crystal optical switches

    NASA Technical Reports Server (NTRS)

    Krawczak, J. A.; Torok, E. J.; Harvey, W. A.; Hewitt, F. G.; Nelson, G. L.

    1984-01-01

    Magnetic stripe domain and liquid crystal devices are being developed and evaluated as fiber optic switches that can be utilized for nonblocking type nxm optical matrix switches in networking and optical processing. Liquid crystal switches are characterized by very low insertion loss and crosstalk, while stripe domain switches commutate in less than one microsecond. Both switches operate on multimode, randomly polarized fiber light with potentially large values for (n,m). The applications of these magnetic stripe domain and liquid crystal devices are discussed.

  16. Bifurcating optical pattern recognition in photorefractive crystals

    NASA Technical Reports Server (NTRS)

    Liu, Hua-Kuang

    1993-01-01

    A concept of bifurcating optical pattern rocognizer (BIOPAR) is described and demonstrated experimentally, using barium titanate crystal. When an input is applied to BIOPAR, the output may be directed to two ports.

  17. Development and validation of an optical SPR biosensor assay for tylosin residues in honey.

    PubMed

    Caldow, Marianne; Stead, Sara L; Day, Joanna; Sharman, Matthew; Situ, Chen; Elliott, Chris

    2005-09-21

    In recent years there has been an increase in the use of tylosin in apiculture as bacterial brood diseases become resistant to oxytetracycline. Confirmatory mass spectrometry based methods have been developed but up until now there has been no complementary screening method available capable of sub 10 microg kg(-1) detection limits. In this paper the development and validation of a screening method using optical biosensor technology is presented. The honey was first dissolved in a phosphate buffer and following solid-phase extraction (SPE) cleanup was analyzed using a Biacore Q instrument. Using the criteria specified in European Commission Decision 2002/657/EC for qualitative screening methods, the detection capability (CCbeta) of the method was determined to be 2.5 microg kg(-)(1). Honey samples containing trace residue levels of tylosin were analyzed by both the biosensor screening method and a LC-MS/MS confirmatory procedure; the results were in good agreement. PMID:16159159

  18. Probing the mechanism of material specific peptides for optical biosensors

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, Sathish K.; Estephan, Elias; Martin, Marta; Cloitre, Thierry; Gergely, Csilla

    2013-05-01

    The possibility to engineer bio-nanomaterials with programmed synthesis and controlled immobilization of biomolecules through biomimetic molecular evolution approach has been demonstrated. Material specific peptides with exquisite molecular recognition function were used as a linker for the attachment of biomolecules. Exploring the origin of peptide material specificity not only opens up rational design approach with precise control over biomimetic bio-sensor design, but more importantly provides a new route of functionalizing for various material surfaces with enhanced sensitivity over classical grafting chemistry. To study the fine prints of experimentally obtained peptides, theoretical understanding of surface interactions may serve as important clues for further refinement. By taking advantage of classical molecular dynamics (MD) simulations and density functional theory (DFT), we investigated the origin of this smart recognition function through the strength of interaction of experimentally selected 12mer peptides revealing high binding affinity towards n+-Si(100). Here, we attempt for the very first time to model the interaction of the peptides (in buffer solution) with semiconductors and we calculate their binding energies at the atomic level, enabling thereby linking direct evidence to our experimental evidence. Several peptide conformations have been taken into account simultaneously upon the surface. Our studies demonstrate that the peptides possess certain recognition function and their high interaction energy with the surface makes them unique among the populations. Our work is a step towards the understanding of the interactions between peptides and semiconductor surfaces that is a highly relevant challenge in the development of novel devices with a high degree of biocompatibility as well.

  19. The Role of Transport Phenomena in Whispering Gallery Mode Optical Biosensor Performance

    NASA Astrophysics Data System (ADS)

    Gamba, Jason

    Whispering gallery mode (WGM) optical resonator sensors have emerged as promising tools for label-free detection of biomolecules in solution. These devices have even demonstrated single-molecule limits of detection in complex biological uids. This extraordinary sensitivity makes them ideal for low-concentration analytical and diagnostic measurements, but a great deal of work must be done toward understanding and optimizing their performance before they are capable of reliable quantitative measurents. The present work explores the physical processes behind this extreme sensitivity and how to best take advantage of them for practical applications of this technology. I begin by examining the nature of the interaction between the intense electromagnetic elds that build up in the optical biosensor and the biomolecules that bind to its surface. This work addresses the need for a coherent and thorough physical model that can be used to predict sensor behavior for a range of experimental parameters. While this knowledge will prove critical for the development of this technology, it has also shone a light on nonlinear thermo-optical and optical phenomena that these devices are uniquely suited to probing. The surprisingly rapid transient response of toroidal WGM biosensors despite sub-femtomolar analyte concentrations is also addressed. The development of asymmetric boundary layers around these devices under ow is revealed to enhance the capture rate of proteins from solution compared to the spherical sensors used previously. These lessons will guide the design of ow systems to minimize measurement time and consumption of precious sample, a key factor in any medically relevant assay. Finally, experimental results suggesting that WGM biosensors could be used to improve the quantitative detection of small-molecule biomarkers in exhaled breath condensate demonstrate how their exceptional sensitivity and transient response can enable the use of this noninvasive method to probe

  20. Hybrid nanoporous silicon optical biosensor architectures for biological sample analysis

    NASA Astrophysics Data System (ADS)

    Bonanno, Lisa M.; Zheng, Hong; DeLouise, Lisa A.

    2010-02-01

    This work focuses on demonstrating proof-of-concept for a novel nanoparticle optical signal amplification scheme employing hybrid porous silicon (PSi) sensors. We are investigating the development of target responsive hydrogels integrated with PSi optical transducers. These hybrid-PSi sensors can be designed to provide a tunable material response to target concentration ranging from swelling to complete chain dissolution. The corresponding refractive index changes are significant and readily detected by the PSi transducer. However, to increase signal to noise, lower the limit of detection, and provide a visual read out capability, we are investigating the incorporation of high refractive index nanoparticles (NP) into the hydrogel for optical signal amplification. These NPs can be nonspecifically encapsulated, or functionalized with bioactive ligands to bind polymer chains or participate in cross linking. In this work, we demonstrate encapsulation of high refractive index QD nanoparticles into a 5wt% polyacrylamide hydrogel crosslinked with N,N'-methylenebisacrylamide (BIS) and N,N Bis-acryloyl cystamine (BAC). A QD loading (~0.29 wt%) produced a 2X larger optical shift compared to the control. Dissolution of disulphide crosslinks, using Tris[2-carboxyethyl] phosphine (TCEP) reducing agent, induced gel swelling and efficient QD release. We believe this hybrid sensor concept constitutes a versatile technology platform capable of detecting a wide range of bio/chemical targets provided target analogs can be linked to the polymer backbone and crosslinks can be achieved with target responsive multivalent receptors, such a antibodies. The optical signal amplification scheme will enable a lower limit of detection sensitivity not yet demonstrated with PSi technology and colorimetric readout visible to the naked eye.

  1. Multidimensional optics and dynamics of liquid crystals

    NASA Astrophysics Data System (ADS)

    Tang, Shouping

    2007-12-01

    In this dissertation, we present an alternative description of multidimensional optics in liquid crystals and uniaxial media, and a systematical investigation on the dynamic properties of twist nematic devices and ECB devices including flow. We also present our investigation on the backflow and dynamic properties of nematic liquid crystals in modulated electric fields. Based on the understanding to backflow and dynamics of liquid crystals, the dynamics of colloidal particles dispersed in nematic liquid crystals and the flow-induced dynamic optical crosstalk between pixels in nematic liquid crystal devices are also studied. The alternative description of multidimensional optics combines the geometrical optics approximation (GOA) with the beam propagation method (BPM). The general treatment of this approach is developed both theoretically and numerically. The investigation on the dynamic properties of twist nematic devices and ECB devices with consideration of backflow is done experimentally, theoretically and numerically. The calculation results are compared with the experimental results, and the optical responses due to backflow are discussed in detail. The investigation on the backflow and dynamic properties of a nematic liquid crystal in modulated electric fields includes director, flow and the shift of liquid crystal fluid. Especially, an important phenomenon, reverseswitching, is shown in this investigation. The dynamics of colloidal particles dispersed in a nematic cela is studied experimentally and by computer simulation. The polarity of director distortions determines the direction of lift force, and the backflow is responsible for the horizontal translational motion. The optical crosstalk between pixels demonstrates the significance of switching-induce flow in pixilated devices. The electrical switching of a pixel in a twisted nematic device can induce an optical response in neighboring pixels. These phenomena are studied in detail, both experimentally and

  2. Porous silicon-based optical biosensors and biochips

    NASA Astrophysics Data System (ADS)

    Rendina, Ivo; Rea, Ilaria; Rotiroti, Lucia; De Stefano, Luca

    2007-04-01

    Porous silicon multilayered microstructures have unique optical and morphological properties that can be exploited in chemical and biological sensing. The large specific surface of nanostructured porous silicon can be chemically modified to link different molecular probes (DNA strands, enzymes, proteins and so on), which recognize the target analytes, in order to enhance the selectivity and specificity of the sensor device. We designed fabricated and characterized several photonic porous silicon-based structures, which were used in sensing some specific molecular interactions. The next step is the integration of the porous silicon-based optical transducer in biochip devices: at this aim, we have tested an innovative anodic bonding process between porous silicon and glass, and its compatibility with the biological probes.

  3. Development of optical biosensor technologies for cardiac troponin recognition.

    PubMed

    Abdolrahim, Mojgan; Rabiee, Mohammad; Alhosseini, Sanaz Naghavi; Tahriri, Mohammadreza; Yazdanpanah, Sara; Tayebi, Lobat

    2015-09-15

    Acute myocardial infarction (AMI) is the leading cause of death among cardiovascular diseases. Among the numerous attempts to develop coronary marker concepts into clinical strategies, cardiac troponin is known as a specific marker for coronary events. The cardiac troponin concentration level in blood has been shown to rise rapidly for 4-10 days after onset of AMI, making it an attractive approach for a long diagnosis window for detection. The extremely low clinical sensing range of cardiac troponin levels consequently makes the methods of detection highly sensitive. In this review, by taking into consideration optical methods applied for cardiac troponin detection, we discuss the most commonly used methods of optical immunosensing and provide an overview of the various diagnostic cardiac troponin immunosensors that have been employed for determination of cardiac troponin over the last several years. PMID:26050627

  4. The BioCD: High-Speed Interferometric Optical Biosensor

    NASA Astrophysics Data System (ADS)

    Nolte, David D.; Zhao, Ming; Wang, Xuefeng

    The bio-optical compact disc (BioCD) is an optical biochip that uses common-path interferometry on a disc spinning at high speed to detect captured proteins. High-speed scanning moves the detection frequency far from 1/f noise, providing high sensitivity and enabling rapid measurement of high-throughput multiplexed assays. The common-path configuration makes it ultra stable with surface height precision down to 20 pm within the focused probe area. This chapter reviews the state of the art in interferometric detection of proteins using spinning-disc interferometry. There are several common-path configurations that achieve phase quadrature for sensitive detection of surface-immobilized proteins. We have implemented differential phase contrast, in-line, microdiffraction, and adaptive optical approaches. Protein patterning provides spatial frequencies for Fourier-domain detection and spatial multiplexing on the BioCD surface. The detection limits of protein are set by a scaling surface mass density, with a metrology limit below 1 pg/mm. Specific immunoassay applications are described for prostate-specific antigen and haptoglobin. A highly multiplexed platform like the BioCD may enable a Moore's Law of protein detection as the scaling capabilities of protein patterning coevolve with proteomics to explore increasingly complex protein interaction networks.

  5. Optical diagnostics of solution crystal growth

    NASA Technical Reports Server (NTRS)

    Kim, Yongkee; Reddy, B. R.; George, Tharayil G.; Lal, Ravindra B.

    1995-01-01

    Solution crystal growth monitoring of LAP/TGS crystals by various optical diagnostics systems, such as conventional and Mach-Zehnder (M-Z) interferometers, optical heterodyne technique, and ellipsometry, is under development. The study of the dynamics of the crystal growth process requires a detailed knowledge of crystal growth rate and the concentration gradient near growing crystals in aqueous solution. Crystal growth rate can be measured using conventional interferometry. Laser beam reflections from the crystal front as well as the back surface interfere with each other, and the fringe shift due to the growing crystal yields information about the growth rate. Our preliminary results indicate a growth rate of 6 A/sec for LAP crystals grown from solution. Single wavelength M-Z interferometry is in use to calculate the concentration gradient near the crystal. Preliminary investigation is in progress using an M-Z interferometer with 2 cm beam diameter to cover the front region of the growing crystal. In the optical heterodyne technique, phase difference between two rf signals (250 KHZ) is measured of which one is a reference signal, and the other growth signal, whose phase changes due to a change in path length as the material grows. From the phase difference the growth rate can also be calculated. Our preliminary results indicate a growth rate of 1.5 A/sec. the seed and solution temperatures were 26.46 C and 27.92 C respectively, and the solution was saturated at 29.0 C. an ellipsometer to measure the growth rate and interface layer is on order from JOBIN YVON, France. All these systems are arranged in such a manner that measurements can be made either sequentially or simultaneously. These techniques will be adapted for flight experiment.

  6. User-friendly, miniature biosensor flow cell for fragile high fundamental frequency quartz crystal resonators.

    PubMed

    Sagmeister, Brigitte P; Graz, Ingrid M; Schwödiauer, Reinhard; Gruber, Hermann; Bauer, Siegfried

    2009-04-15

    For the application of high fundamental frequency (HFF) quartz crystal resonators as ultra sensitive acoustic biosensors, a tailor-made quartz crystal microbalance (QCM) flow cell has been fabricated and tested. The cell permits an equally fast and easy installation and replacement of small and fragile HFF sensors. Usability and simple fabrication are two central features of the HFF-QCM flow cell. Mechanical, thermal, electrical and chemical requirements are considered. The design of the cell combines these, partially contradictory, requirements within a simple device. Central design concepts are discussed and a brief description of the fabrication, with a special focus on the preparation of crucial parts, is provided. For test measurements, the cell was equipped with a standard 50 MHz HFF resonator which had been surface-functionalised with a self-assembled monolayer of 1-octadecanethiol. The reliable performance is demonstrated with two types of experiments: the real time monitoring of phospholipid monolayer formation and its removal with detergent, as well as step-wise growth of a protein multilayer system by an alternating immobilisation of streptavidin and biotinylated immunoglobulin G. PMID:19231152

  7. Fiber-Optic Chemiluminescent Biosensors for Monitoring Aqueous Alcohols and Other Water Quality Parameters

    NASA Technical Reports Server (NTRS)

    Verostko, Charles E. (Inventor); Atwater, James E. (Inventor); Akse, James R. (Inventor); DeHart, Jeffrey L. (Inventor); Wheeler, Richard R. (Inventor)

    1998-01-01

    A "reagentless" chemiluminescent biosensor and method for the determination of hydrogen peroxide, ethanol and D-glucose in water is disclosed. An aqueous stream is basified by passing it through a solid phase base bed. Luminol is then dissolved in the basified effluent at a controlled rate. Oxidation of the luminol is catalyzed by the target chemical to produce emitted light. The intensity of the emitted light is detected as a measure of the target chemical concentration in the aqueous stream. The emitted light can be transmitted by a fiber optic bundle to a remote location from the aqueous stream for a remote reading of the target chemical concentration.

  8. Biosensors and chemosensors based on the optical responses of polydiacetylenes.

    PubMed

    Chen, Xiaoqiang; Zhou, Guodong; Peng, Xiaojun; Yoon, Juyoung

    2012-07-01

    Polydiacetylenes (PDAs), a family of conjugated polymers, have very unique electrical and optical properties. Upon environmental stimulation, such as by viruses, proteins, DNAs, metal ions, organic molecules etc., the blue PDAs can undergo a colorimetric transition from blue to red, which is accompanied by a fluorescence enhancement. Since the first report on polymerized diacetylene molecules as sensors of influenza virus, the development of efficient sensory systems based on PDAs continues to be of great interest. This tutorial review highlights the recent advances in bio- and chemo-sensors derived from polydiacetylenes. PMID:22569480

  9. Development and study the performance of PBA cladding modified fiber optic intrinsic biosensor for urea detection

    NASA Astrophysics Data System (ADS)

    Botewad, S. N.; Pahurkar, V. G.; Muley, G. G.

    2016-05-01

    The fabrication and study of a cladding modified fiber optic intrinsic urea biosensor based on evanescent wave absorbance has been presented. The sensor was prepared using cladding modification technique by removing a small portion of cladding of an optical fiber and modifying with an active cladding of porous polyaniline-boric acid (PBA) matrix to immobilize enzyme-urease through cross-linking via glutaraldehyde. The nature of as-synthesized and deposited PBA film on fiber optic sensing element was studied by ultraviolet-visible (UV-vis) spectroscopy and X-ray diffraction (XRD) analysis. The performance of the developed sensor was studied for different urea concentrations in solutions prepared in phosphate buffer.

  10. Fabrication of polyaniline-HCl cladding modified fiber optic intrinsic biosensor for glucose detection

    NASA Astrophysics Data System (ADS)

    Pahurkar, Vikas; Tamgadge, Yuoraj; Muley, Gajanan

    2016-05-01

    In the present study, we have fabricated and studied response of cladding modified fiber optic intrinsic glucose biosensor (FOIGB). The optical fiber was used as a light transforming waveguide and sensing element fabricated over it by applying a thin layer of polymer. The cladding of the sensor was modified with the polyaniline-hydrochloric acid (PANI-HCl) polymer matrix. The PANI-HCl matrix provides an amorphous morphology useful to immobilize glucose oxidase (GOx) biomolecules through cross-linking technique via glutaraldehyde. The present sensor was used to detect the glucose analyte in the solution. In the sensing response study of FOIGB toward glucose, novel modal power distribution (MPD) technique was used. The reaction between GOx and glucose changes the optical properties of prepared FOIGB and hence modify MPD at output as a function of glucose concentration. The nature and surface morphology of PANI-HCl matrix has been studied.

  11. Design and realization of highly stable porous silicon optical biosensor based on proteins from extremophiles

    NASA Astrophysics Data System (ADS)

    De Stefano, Luca; Rotiroti, Lucia; Rea, Ilaria; De Tommasi, Edoardo; Vitale, Annalisa; Rossi, Mosè; Rendina, Ivo; D'Auria, Sabato

    2007-05-01

    The interaction between an analyte and a biological recognition system is normally detected in biosensors by the transducer element which converts the molecular event into a measurable effect, such as an electrical or optical signal. Porous silicon microstructures have unique optical and morphological properties that can be exploited in biosensing. The large specific surface area (even greater than 500 m2/cm 3) and the resonant optical response allow detecting the effect of a change in refractive index of liquid solutions, which interact with the porous matrix, with very high sensitivity. Moreover, the porous silicon surface can be chemically modified to link the bioprobe which recognize the target analytes, in order to enhance the selectivity and specificity of the sensor device. The molecular probe we used was purified by an extremophile organism, Thermococcus litoralis: the protein is very stable in a wide range of temperatures even if with different behavior respect to the interaction with the ligand.

  12. Optimization and Application of Reflective LSPR Optical Fiber Biosensors Based on Silver Nanoparticles

    PubMed Central

    Chen, Jiangping; Shi, Se; Su, Rongxin; Qi, Wei; Huang, Renliang; Wang, Mengfan; Wang, Libing; He, Zhimin

    2015-01-01

    In this study, we developed a reflective localized surface plasmon resonance (LSPR) optical fiber sensor, based on silver nanoparticles (Ag NPs). To enhance the sensitivity of the LSPR optical sensor, two key parameters were optimized, the length of the sensing area and the coating time of the Ag NPs. A sensing length of 1.5 cm and a 1-h coating time proved to be suitable conditions to produce highly sensitive sensors for biosensing. The optimized sensor has a high refractive index sensitivity of 387 nm/RIU, which is much higher than that of other reported individual silver nanoparticles in solutions. Moreover, the sensor was further modified with antigen to act as a biosensor. Distinctive wavelength shifts were found after each surface modification step. In addition, the reflective LSPR optical fiber sensor has high reproducibility and stability. PMID:26016910

  13. The development of FRET-based dual receptor optical biosensor

    NASA Astrophysics Data System (ADS)

    Xu, Juntao

    The focus of the research presented in this dissertation is the development of a new FRET-based dual receptor sensing method for detecting the human immunodeficiency virus (HIV). The new detection method presented in this dissertation imitates the way HIV infects cells. It utilizes the two receptor-binding event and integrates a chemical transducer system with two unique protein receptors, CD4 and mAb (HIV-1 gp120 monoclonal antibody), which both bind to gp120. The chemical transduction system is based on the distance-dependant principle of fluorescence resonance energy transfer (FRET). The work presented in this dissertation attempts to demonstrate the feasibility of this new sensing method both in solution and on an optical fiber. Appropriate FRET pairs which have high energy transfer efficiency as well as good conjugation properties with receptors were selected and optimized. The two receptors, CD4 and mAb which specifically bind to gp120, were conjugated to one of the optimized FRET fluorophore pairs, AMCA-NHS (succinimidyl-7-amino-4-methylcoumarin-3-acetic acid) and FITC (fluorescein isothiocyanate), respectively. For the solution test, the viral protein gp120, which is the featured protein on the surface of HIV-1, was detected by the mixed solution of the two FRET pair tagged receptors. A spectrofluorometer was used to detect the fluorescent change between AMCA-NHS and FITC peak intensities when the receptors bind to the gp120. Specific binding and non-specific binding gp120 were used to test the selectivity of this method. The results of the solution test indicated that FRET-conjugated receptors can efficiently distinguish the presence of specific and non-specific binding gp120 and proved the feasibility of the FRET-based dual receptor method in detecting the presence of gp120 with a limit of detection of 5ng/ml (0.5nM) in solution. For the optical fiber test, two FRET-conjugated receptors were immobilized onto an optical fiber silica core tip to detect the

  14. High density array fabrication and readout method for a fiber optic biosensor

    DOEpatents

    Pinkel, Daniel; Gray, Joe; Albertson, Donna G.

    2000-01-01

    The invention relates to the fabrication and use of biosensors comprising a plurality of optical fibers each fiber having attached to its "sensor end" biological "binding partners" (molecules that specifically bind other molecules to form a binding complex such as antibody-antigen, lectin-carbohydrate, nucleic acid-nucleic acid, biotin-avidin, etc.). The biosensor preferably bears two or more different species of biological binding partner. The sensor is fabricated by providing a plurality of groups of optical fibers. Each group is treated as a batch to attach a different species of biological binding partner to the sensor ends of the fibers comprising that bundle. Each fiber, or group of fibers within a bundle, may be uniquely identified so that the fibers, or group of fibers, when later combined in an array of different fibers, can be discretely addressed. Fibers or groups of fibers are then selected and discretely separated from different bundles. The discretely separated fibers are then combined at their sensor ends to produce a high density sensor array of fibers capable of assaying simultaneously the binding of components of a test sample to the various binding partners on the different fibers of the sensor array. The transmission ends of the optical fibers are then discretely addressed to detectors--such as a multiplicity of optical sensors. An optical signal, produced by binding of the binding partner to its substrate to form a binding complex, is conducted through the optical fiber or group of fibers to a detector for each discrete test. By examining the addressed transmission ends of fibers, or groups of fibers, the addressed transmission ends can transmit unique patterns assisting in rapid sample identification by the sensor.

  15. High density array fabrication and readout method for a fiber optic biosensor

    DOEpatents

    Pinkel, Daniel; Gray, Joe

    1997-01-01

    The invention relates to the fabrication and use of biosensors comprising a plurality of optical fibers each fiber having attached to its "sensor end" biological "binding partners" (molecules that specifically bind other molecules to form a binding complex such as antibody-antigen, lectin-carbohydrate, nucleic acid-nucleic acid, biotin-avidin, etc.). The biosensor preferably bears two or more different species of biological binding partner. The sensor is fabricated by providing a plurality of groups of optical fibers. Each group is treated as a batch to attach a different species of biological binding partner to the sensor ends of the fibers comprising that bundle. Each fiber, or group of fibers within a bundle, may be uniquely identified so that the fibers, or group of fibers, when later combined in an array of different fibers, can be discretely addressed. Fibers or groups of fibers are then selected and discretely separated from different bundles. The discretely separated fibers are then combined at their sensor ends to produce a high density sensor array of fibers capable of assaying simultaneously the binding of components of a test sample to the various binding partners on the different fibers of the sensor array. The transmission ends of the optical fibers are then discretely addressed to detectors--such as a multiplicity of optical sensors. An optical signal, produced by binding of the binding partner to its substrate to form a binding complex, is conducted through the optical fiber or group of fibers to a detector for each discrete test. By examining the addressed transmission ends of fibers, or groups of fibers, the addressed transmission ends can transmit unique patterns assisting in rapid sample identification by the sensor.

  16. High density array fabrication and readout method for a fiber optic biosensor

    DOEpatents

    Pinkel, Daniel; Gray, Joe; Albertson, Donna G.

    2002-01-01

    The invention relates to the fabrication and use of biosensors comprising a plurality of optical fibers each fiber having attached to its "sensor end" biological "binding partners" (molecules that specifically bind other molecules to form a binding complex such as antibody-antigen, lectin-carbohydrate, nucleic acid-nucleic acid, biotin-avidin, etc.). The biosensor preferably bears two or more different species of biological binding partner. The sensor is fabricated by providing a plurality of groups of optical fibers. Each group is treated as a batch to attach a different species of biological binding partner to the sensor ends of the fibers comprising that bundle. Each fiber, or group of fibers within a bundle, may be uniquely identified so that the fibers, or group of fibers, when later combined in an array of different fibers, can be discretely addressed. Fibers or groups of fibers are then selected and discretely separated from different bundles. The discretely separated fibers are then combined at their sensor ends to produce a high density sensor array of fibers capable of assaying simultaneously the binding of components of a test sample to the various binding partners on the different fibers of the sensor array. The transmission ends of the optical fibers are then discretely addressed to detectors--such as a multiplicity of optical sensors. An optical signal, produced by binding of the binding partner to its substrate to form a binding complex, is conducted through the optical fiber or group of fibers to a detector for each discrete test. By examining the addressed transmission ends of fibers, or groups of fibers, the addressed transmission ends can transmit unique patterns assisting in rapid sample identification by the sensor.

  17. High density array fabrication and readout method for a fiber optic biosensor

    DOEpatents

    Pinkel, D.; Gray, J.

    1997-11-25

    The invention relates to the fabrication and use of biosensors comprising a plurality of optical fibers each fiber having attached to its ``sensor end`` biological ``binding partners`` (molecules that specifically bind other molecules to form a binding complex such as antibody-antigen, lectin-carbohydrate, nucleic acid-nucleic acid, biotin-avidin, etc.). The biosensor preferably bears two or more different species of biological binding partner. The sensor is fabricated by providing a plurality of groups of optical fibers. Each group is treated as a batch to attach a different species of biological binding partner to the sensor ends of the fibers comprising that bundle. Each fiber, or group of fibers within a bundle, may be uniquely identified so that the fibers, or group of fibers, when later combined in an array of different fibers, can be discretely addressed. Fibers or groups of fibers are then selected and discretely separated from different bundles. The discretely separated fibers are then combined at their sensor ends to produce a high density sensor array of fibers capable of assaying simultaneously the binding of components of a test sample to the various binding partners on the different fibers of the sensor array. The transmission ends of the optical fibers are then discretely addressed to detectors--such as a multiplicity of optical sensors. An optical signal, produced by binding of the binding partner to its substrate to form a binding complex, is conducted through the optical fiber or group of fibers to a detector for each discrete test. By examining the addressed transmission ends of fibers, or groups of fibers, the addressed transmission ends can transmit unique patterns assisting in rapid sample identification by the sensor. 9 figs.

  18. DNA-Aptamer optical biosensors based on a LPG-SPR optical fiber platform for point-of-care diagnostic

    NASA Astrophysics Data System (ADS)

    Coelho, L.; Queirós, R. B.; Santos, J. L.; Martins, M. Cristina L.; Viegas, D.; Jorge, P. A. S.

    2014-03-01

    Surface Plasmon Resonance (SPR) is the base for some of the most sensitive label free optical fiber biosensors. However, most solutions presented to date require the use of fragile fiber optic structure such as adiabatic tapers or side polished fibers. On the other hand, long-period fiber gratings (LPG) present themselves as an interesting solution to attain an evanescent wave refractive index sensor platform while preserving the optical fiber integrity. The combination of these two approaches constitute a powerful platform that can potentially reach the highest sensitivities as it was recently demonstrated by detailed theoretical study [1, 2]. In this work, a LPG-SPR platform is explored in different configurations (metal coating between two LPG - symmetric and asymmetric) operating in the telecom band (around 1550 nm). For this purpose LPGs with period of 396 μm are combined with tailor made metallic thin films. In particular, the sensing regions were coated with 2 nm of chromium to improve the adhesion to the fiber and 16 nm of gold followed by a 100 nm thick layer of TiO2 dielectric material strategically chosen to attain plasmon resonance in the desired wavelength range. The obtained refractometric platforms were then validated as a biosensor. For this purpose the detection of thrombin using an aptamer based probe was used as a model system for protein detection. The surface of the sensing fibers were cleaned with isopropanol and dried with N2 and then the aminated thrombin aptamer (5'-[NH2]- GGTTGGTGTGGTTGG-3') was immobilized by physisorption using Poly-L-Lysine (PLL) as cationic polymer. Preliminary results indicate the viability of the LPFG-SPR-APTAMER as a flexible platforms point of care diagnostic biosensors.

  19. A fiber-optic sorbitol biosensor based on NADH fluorescence detection toward rapid diagnosis of diabetic complications.

    PubMed

    Gessei, Tomoko; Arakawa, Takahiro; Kudo, Hiroyuki; Mitsubayashi, Kohji

    2015-09-21

    Accumulation of sorbitol in the tissue is known to cause microvascular diabetic complications. In this paper, a fiber-optic biosensor for sorbitol which is used as a biomarker of diabetic complications was developed and tested. The biosensor used a sorbitol dehydrogenase from microorganisms of the genus Flavimonas with high substrate specificity and detected the fluorescence of reduced nicotinamide adenine dinucleotide (NADH) by the enzymatic reaction. An ultraviolet light emitting diode (UV-LED) was used as the excitation light source of NADH. The fluorescence of NADH was detected using a spectrometer or a photomultiplier tube (PMT). The UV-LED and the photodetector were coupled using a Y-shaped optical fiber. In the experiment, an optical fiber probe with a sorbitol dehydrogenase immobilized membrane was placed in a cuvette filled with a phosphate buffer containing the oxidized form of nicotinamide adenine dinucleotide (NAD(+)). The changes in NADH fluorescence intensity were measured after adding a standard sorbitol solution. According to the experimental assessment, the calibration range of the sorbitol biosensor systems using a spectrometer and a PMT was 5.0-1000 μmol L(-1) and 1.0-1000 μmol L(-1), respectively. The sorbitol biosensor system using the sorbitol dehydrogenase from microorganisms of the genus Flavimonas has high selectivity and sensitivity compared with that from sheep liver. The sorbitol biosensor allows for point-of-care testing applications or daily health care tests for diabetes patients. PMID:26244794

  20. Optical analysis of crystal growth

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.; Passeur, Andrea; Harper, Sabrina

    1994-01-01

    Processing and data reduction of holographic images from Spacelab presents some interesting challenges in determining the effects of microgravity on crystal growth processes. Evaluation of several processing techniques, including the Computerized Holographic Image Processing System and the image processing software ITEX150, will provide fundamental information for holographic analysis of the space flight data.

  1. Recognition of apoptotic cells by viable cells is specific, ubiquitous, and species independent: analysis using photonic crystal biosensors

    PubMed Central

    Pattabiraman, Goutham; Lidstone, Erich A.; Palasiewicz, Karol; Cunningham, Brian T.; Ucker, David S.

    2014-01-01

    Apoptotic recognition is innate and linked to a profound immune regulation (innate apoptotic immunity [IAI]) involving anti-inflammatory and immunosuppressive responses. Many of the molecular and mechanistic details of this response remain elusive. Although immune outcomes can be quantified readily, the initial specific recognition events have been difficult to assess. We developed a sensitive, real-time method to detect the recognition of apoptotic cells by viable adherent responder cells, using a photonic crystal biosensor approach. The method relies on characteristic spectral shifts resulting from the specific recognition and dose-dependent interaction of adherent responder cells with nonadherent apoptotic targets. Of note, the biosensor provides a readout of early recognition-specific events in responder cells that occur distal to the biosensor surface. We find that innate apoptotic cell recognition occurs in a strikingly species-independent manner, consistent with our previous work and inferences drawn from indirect assays. Our studies indicate obligate cytoskeletal involvement, although apoptotic cell phagocytosis is not involved. Because it is a direct, objective, and quantitative readout of recognition exclusively, this biosensor approach affords a methodology with which to dissect the early recognition events associated with IAI and immunosuppression. PMID:24694594

  2. Diatom-based label-free optical biosensor for biomolecules.

    PubMed

    Viji, S; Anbazhagi, M; Ponpandian, N; Mangalaraj, D; Jeyanthi, S; Santhanam, P; Devi, A Shenbaga; Viswanathan, C

    2014-10-01

    Diatoms are unicellular algae, which fabricates ornate biosilica shells called frustules that possess a surface rich in reactive silanol (Si-OH) groups. The intrinsic patterned porous structure of diatom frustules at nanoscale can be exploited in the effective detection of biomolecules. In this study, the frustules of a specific diatom Amphora sp. has been functionalized to detect bovine serum albumin (BSA). The functionalization of the diatom frustule substrate is achieved by using 3-aminopropyltriethoxysilane (APES). The field emission scanning electron microscopy (FESEM) results showed an ornately patterned surface of the frustule valve ordered at nanoscale. The Fourier transform infrared (FTIR) spectra confirmed the N-H bending and stretching of the amine group after amine functionalization. The emission peaks in the photoluminescence (PL) spectra of the amine-functionalized diatom biosilica selectively enhanced the intensity by a factor of ten when compared to that of a bare diatom biosilica. The result showed a significant quenching of PL intensity of BSA at around 445 nm due to the interaction of amine-functionalized diatom-BSA protein complex. The detection limit was found to be 3 × 10(-5) M of BSA protein. Hence, the study proves that the functionalized frustule of Amphora sp. is an effective quantitative analytical tool for optical label-free biosensing applications. PMID:24989453

  3. Liquid-crystal fiber-optic switch.

    PubMed

    Soref, R A

    1979-05-01

    An adjustable access coupler for multimode fiber-optic networks has been constructed, based on the voltage-tunable total-internal-reflection effect in nematic liquid crystals. Fibers are coupled via graded-index rod lenses at normal incidence to flint-glass prisms in contact with a 6-microm liquid-crystal layer. The achromatic four-port switch has a 1.6-dB optical insertion loss, a tap ratio controllable from -4.6 to -48 dB, a directionality of 44 dB, and an operating voltage of 5 to 20 V rms. PMID:19687832

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

    PubMed

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

    2016-05-01

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

  5. Monitoring glutamine in animal cell cultures using a chemiluminescence fiber optic biosensor.

    PubMed

    Cattaneo, M V; Luong, J H

    1993-03-15

    Together with flow injection analysis (FIA), a chemiluminescence (CL) fiber optic biosensor system has been developed for determining glutamine in animal cell cultures. Glutaminase (GAH) and glutamate oxidase (GLO) were onto separate porous aminopropyl glass beads via glutaraldehyde activation and packed to form an enzyme column. These two enzymes acted in sequence on glutamine to produce hydrogen peroxide, which was then reacted with luminol in the presence of ferricyanide to produce a light signal. An anion exchanger was introduced on-line to eliminate interfering endogenous glutamate in view of its negative charge at pH above 3.22 (isoelectric pH). Among several resins tested, the acetate form was most effective, and this type of ion exchanger also effectively adsorbed uric acid, acetaminophen, and aspartic acid.There was an excellent linear relationship between the CL response and standard glutamine concentration in the range 1 to 100 muM. A complete analysis could be performed in 2 min, including sampling and washing with a good reproducibility (+/- 4.4%). Both the bi-enzymic and ion exchange columns were useful for at least 500 analyses when the biosensor system was applied for the glutamine determination in murine hybridoma cell cultures and insect cell cultures. The values obtained compared well with those of HPLC, thus validating the applicability of the CL fiber optic system. PMID:18609602

  6. Optical resonance-enhanced absorption-based near-field immunochip biosensor for allergen detection.

    PubMed

    Maier, Irene; Morgan, Michael R A; Lindner, Wolfgang; Pittner, Fritz

    2008-04-15

    An optical immunochip biosensor has been developed as a rapid method for allergen detection in complex food matrixes, and its application evaluated for the detection of the egg white allergens, ovalbumin and ovomucoid. The optical near-field phenomenon underlying the basic principle of the sensor design is called resonance-enhanced absorption (REA), which utilizes gold nanoparticles (Au NPs) as signal transducers in a highly sensitive interferometric setup. Using this approach, a novel, simple, and rapid colorimetric solid-phase immunoassay on a planar chip substrate was realized in direct and sandwich assay formats, with a detection system that does not require any instrumentation for readout. Semiquantitative immunochemical responses are directly visible to the naked eye of the analyst. The biosensor shows concentration-dependent color development by capturing antibody-functionalized Au NPs on allergen-coated chips and has a detection limit of 1 ng/mL. To establish a rapid method, we took advantage of the physicochemical microenvironment of the Au NP-antibody bioconjugate to be bound directly over an interacting poly(styrene-methyl methacrylate) interlayer by an immobilized antigen. In the direct assay format, a coating time with allergen of only 5 min under "soft" nondenaturing conditions was sufficient for accurate reproducibility and sensitivity. In conclusion, the REA-based immunochip sensor is easy to fabricate, is reproducible and selective in its performance, has minimal technical requirements, and will enable high-throughput screening of affinity binding interactions in technological and medical applications. PMID:18358010

  7. Optical biosensor consisting of glutathione-S-transferase for detection of captan.

    PubMed

    Choi, Jeong-Woo; Kim, Young-Kee; Song, Sun-Young; Lee, In-ho; Lee, Won-Hong

    2003-10-15

    The optical biosensor consisting of a glutathione-S-transferase (GST)-immobilized gel film was developed to detect captan in contaminated water. The sensing scheme was based on the decrease of yellow product, s-(2,4-dinitrobenzene) glutathione, produced from substrates, 1-chloro-2,4-dinitrobenzene (CDNB) and glutathione (GSH), due to the inhibition of GST reaction by captan. Absorbance of the product as the output of enzyme reaction was detected and the light was guided through the optical fibers. The enzyme reactor of the sensor system was fabricated by the gel entrapment technique for the immobilized GST film. The immobilized GST had the maximum activity at pH 6.5. The optimal concentrations of substrates were determined with 1 mM for both of CDNB and GSH. The optimum concentration of enzyme was also determined with 100 microg/ml. The activity of immobilized enzyme was fairly sustained during 30 days. The proposed biosensor could successfully detect the captan up to 2 ppm and the response time to steady signal was about 15 min. PMID:12941561

  8. Novel FIA chemiluminescence fiber optic biosensor for urinary and blood glucose

    NASA Astrophysics Data System (ADS)

    Cattaneo, Maurice V.; Luong, J. H. T.

    1993-05-01

    A chemiluminescence fiber optic biosensor system coupled to FIA was developed to measure glucose in bodily fluids. Glucose oxidase was immobilized on a preactivated nylon membrane and attached to the tip of a fiber optic bundle. This enzyme acts on (beta) -D-glucose to produce hydrogen peroxide which was then reacted with luminol in the presence of ferricyanide to produce a light signal. The sensitivity of the biosensor was determined to be 32 +/- 0.65 nV (mu) M-1 with a minimum detectable level of 5 (mu) M. The addition of a glucose oxidase column with a higher enzyme loading improved the sensitivity by at least 25-fold thus permitting the measurement of the lower glucose levels found in urine. The enzyme membrane could be reused for at least 50 analyses while the glucose oxidase column could be reused for over 500 analyses without losing the original activity. Endogenous ascorbate and urate usually present in urine samples which interfere with the chemiluminescence signal were effectively retained by an upstream ion exchange column. When applied for the determination of urinary and blood glucose levels, the results obtained compared well with those of the widely accepted hexokinase assay.

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

    PubMed Central

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

    2016-01-01

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

  10. Optical monitoring of protein crystal growth

    NASA Technical Reports Server (NTRS)

    Choudry, A.

    1988-01-01

    The possibility of using various optical techniques for detecting the onset of nucleation in protein crystal growth was investigated. Direct microscopy, general metrologic techniques, light scattering, ultraviolet absorption, and interferometry are addressed along with techniques for determining pH value. The necessity for collecting basic data on the optical properties of the growth solution as a prerequisite to the evaluation of monitoring techniques is pointed out.

  11. Accurate Optical Detection of Amphiphiles at Liquid-Crystal-Water Interfaces

    NASA Astrophysics Data System (ADS)

    Popov, Piotr; Mann, Elizabeth K.; Jákli, Antal

    2014-04-01

    Liquid-crystal-based biosensors utilize the high sensitivity of liquid-crystal alignment to the presence of amphiphiles adsorbed to one of the liquid-crystal surfaces from water. They offer inexpensive, easy optical detection of biologically relevant molecules such as lipids, proteins, and cells. Present techniques use linear polarizers to analyze the alignment of the liquid crystal. The resulting images contain information not only about the liquid-crystal tilt with respect to the surface normal, the quantity which is controlled by surface adsorption, but also on the uncontrolled in-plane liquid-crystal alignment, thus making the detection largely qualitative. Here we show that detecting the liquid-crystal alignment between circular polarizers, which are only sensitive to the liquid-crystal tilt with respect to the interface normal, makes possible quantitative detection by measuring the transmitted light intensity with a spectrophotometer. Following a new procedure, not only the concentration dependence of the optical path difference but also the film thickness and the effective birefringence can be determined accurately. We also introduce a new "dynamic" mode of sensing, where (instead of the conventional "steady" mode, which detects the concentration dependence of the steady-state texture) we increase the concentration at a constant rate.

  12. Improving the binding efficiency of quartz crystal microbalance biosensors by applying the electrothermal effect

    PubMed Central

    Huang, Yao-Hung; Chang, Jeng-Shian; Chao, Sheng D.; Wu, Kuang-Chong; Huang, Long-Sun

    2014-01-01

    A quartz crystal microbalance (QCM) serving as a biosensor to detect the target biomolecules (analytes) often suffers from the time consuming process, especially in the case of diffusion-limited reaction. In this experimental work, we modify the reaction chamber of a conventional QCM by integrating into the multi-microelectrodes to produce electrothermal vortex flow which can efficiently drive the analytes moving toward the sensor surface, where the analytes were captured by the immobilized ligands. The microelectrodes are placed on the top surface of the chamber opposite to the sensor, which is located on the bottom of the chamber. Besides, the height of reaction chamber is reduced to assure that the suspended analytes in the fluid can be effectively drived to the sensor surface by induced electrothermal vortex flow, and also the sample costs are saved. A series of frequency shift measurements associated with the adding mass due to the specific binding of the analytes in the fluid flow and the immobilized ligands on the QCM sensor surface are performed with or without applying electrothermal effect (ETE). The experimental results show that electrothermal vortex flow does effectively accelerate the specific binding and make the frequency shift measurement more sensible. In addition, the images of the binding surfaces of the sensors with or without applying electrothermal effect are taken through the scanning electron microscopy. By comparing the images, it also clearly indicates that ETE does raise the specific binding of the analytes and ligands and efficiently improves the performance of the QCM sensor. PMID:25538808

  13. Real-time multianalyte biosensors based on interference-free multichannel monolithic quartz crystal microbalance.

    PubMed

    Jaruwongrungsee, Kata; Waiwijit, Uraiwan; Wisitsoraat, Anurat; Sangworasil, Manas; Pintavirooj, Chuchart; Tuantranont, Adisorn

    2015-05-15

    In this work, we design, fabricate and characterize a new interference-free multichannel monolithic quartz crystal microbalance (MQCM) platform for bio-sensing applications. Firstly, interference due to thickness-shear vibration mode coupling between channels in MQCM array is effectively suppressed by interposing a polydimethylsiloxane wall between adjacent QCM electrodes on a quartz substrate to form inverted-mesa-like structure. In addition, the electrical coupling due to the electrical impedance of solution is diminished by extending the flow path between them with an extended-design flow channel. The electrical testing results show that individual QCM signal is unaffected by those of adjacent channels under liquid loading, signifying the achievement of interference-free MQCM. The MQCM is applied for multi-analyte biosensing of IgG and HSA. The anti-IgG and anti-HSA are separately immobilized on two adjacent QCM electrodes, which are subsequently blocked with BSA to avoid unspecific binding. The MQCM biosensors are tested with single- and double-analyte solutions under continuous flow of buffer. The IgG and HSA QCM sensors only show frequency shift responses to their corresponding analytes and there are very small cross frequency shifts due to remnant unspecific binding. Moreover, MQCM sensors show approximately linear frequency shift response with analyte concentration. Therefore, the developed MQCM platform is promising for real-time interference-free label-free detection and quantification of multiple bio-analytes. PMID:25307623

  14. Optical crystal temperature gauge with fiber optic connections

    SciTech Connect

    Sharma, M.M.

    1982-07-01

    An optical temperature gauge uses a semiconductor crystal with a band-edge shift property which is temperature dependent. An external narrow band light source provides optical excitation through a optical fiber and light energy thus passed through the crystal is conveyed by a second optical fiber to a light-to-electric transducers at an external location. The crystal can be located in cryogenic or other systems, to provide remote read-out. The light wavelength is varied (scanned) in a repetitive pattern in source with the instantaneous wavelength passing over the band-edge wavelength during each cycle of the scan. The timing of the crossover is related to the temperature of the crystal by electronic means. Several alternative elements of instrumentation are disclosed. A variation in the basic measurement apparatus is also disclosed, in which the band gap voltage of a light source such as a laser diode is evaluated at the time of band-edge crossover in the crystal and converted to a temperature value. Official Gazette of the U.S. Patent and Trademark Office

  15. A stable, label-free optical interferometric biosensor based on TiO2 nanotube arrays.

    PubMed

    Mun, Kyu-Shik; Alvarez, Sara D; Choi, Won-Youl; Sailor, Michael J

    2010-04-27

    Optical interferometry of a thin film array of titanium dioxide (TiO2) nanotubes allows the label-free sensing of rabbit immunoglobulin G (IgG). A protein A capture probe is used, which is immobilized on the inner pore walls of the nanotubes by electrostatic adsorption. Control experiments using IgG from chicken (which does not bind to protein A) confirms the specificity of the protein A-modified TiO2 nanotube array sensor. The aqueous stability of the TiO2 nanotube array was examined and compared with porous silica (SiO2), a more extensively studied thin film optical biosensor. The TiO2 nanotube array is stable in the pH range 2 to 12, whereas the porous SiO2 sensor displays significant degradation at pH > 8. PMID:20356100

  16. An Optical Biosensor from Green Fluorescent Escherichia coli for the Evaluation of Single and Combined Heavy Metal Toxicities

    PubMed Central

    Futra, Dedi; Heng, Lee Yook; Ahmad, Asmat; Surif, Salmijah; Ling, Tan Ling

    2015-01-01

    A fluorescence-based fiber optic toxicity biosensor based on genetically modified Escherichia coli (E. coli) with green fluorescent protein (GFP) was developed for the evaluation of the toxicity of several hazardous heavy metal ions. The toxic metals include Cu(II), Cd(II), Pb(II), Zn(II), Cr(VI), Co(II), Ni(II), Ag(I) and Fe(III). The optimum fluorescence excitation and emission wavelengths of the optical biosensor were 400 ± 2 nm and 485 ± 2 nm, respectively. Based on the toxicity observed under optimal conditions, the detection limits of Cu(II), Cd(II), Pb(II), Zn(II), Cr(VI), Co(II), Ni(II), Ag(I) and Fe(III) that can be detected using the toxicity biosensor were at 0.04, 0.32, 0.46, 2.80, 100, 250, 400, 720 and 2600 μg/L, respectively. The repeatability and reproducibility of the proposed biosensor were 3.5%–4.8% RSD (relative standard deviation) and 3.6%–5.1% RSD (n = 8), respectively. The biosensor response was stable for at least five weeks, and demonstrated higher sensitivity towards metal toxicity evaluation when compared to a conventional Microtox assay. PMID:26029952

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

    PubMed

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

    2010-05-15

    This paper presents a disposable microfluidic biochip with on-chip molecularly imprinted biosensors for optical detection of anesthetic propofol. So far, the methods to detect anesthetic propofol in hospitals are liquid chromatography (LC), high-performance liquid chromatography (HPLC), and gas chromatography-mass spectroscopy (GC-MS). These conventional instruments are bulky, expensive, and not ease of access. In this work, a novel plastic microfluidic biochip with on-chip anesthetic biosensor has been developed and characterized for rapid detection of anesthetic propofol. The template-molecule imprinted polymers were integrated into microfluidic biochips to be used for detecting anesthetic propofol optically at 655 nm wavelength after the reaction of propofol with color reagent. Experimental results show that the sensitivity of the microfluidic biochip with on-chip molecularly imprinted polymers (MIPs) biosensor is 6.47 mV/(ppm mm(2)). The specific binding of MIP to non-imprinted polymer (NIP) is up to 456%. And the detection limit of the microsystem is 0.25 ppm with a linear detection range from 0.25 to 10 ppm. The disposable microfluidic biochip with on-chip anesthetic biosensor using molecularly imprinted polymers presented in this work showed excellent performance in separation and sensing of anesthetic propofol molecules. While compared to large-scale conventional instruments, the developed microfluidic biochips with on-chip MIP biosensors have the advantages of compact size, high sensitivity, high selectivity, low cost, and fast response. PMID:20206494

  18. Crystal-field effects in fluoride crystals for optical refrigeration

    SciTech Connect

    Hehlen, Markus P

    2010-01-01

    The field of optical refrigeration of rare-earth-doped solids has recently seen an important breakthrough. The cooling of a YLiF{sub 4} (YLF) crystal doped with 5 mol% Yb3+ to 155 K by Seletskiy et al [NPhot] has surpassed the lowest temperatures ({approx}170 K for {approx}100 mW cooling capacity) that are practical with commercial multi-stage thermoelectric coolers (TEC) [Glaister]. This record performance has advanced laser cooling into an application relevant regime and has put first practical optical cryocoolers within reach. The result is also relevant from a material perspective since for the first time, an Yb3+-doped crystal has outperformed an Yb3+-doped glass. The record temperature of 208 K was held by the Yb3+-doped fluorozirconate glass ZBLAN. Advanced purification and glass fabrication methods currently under development are expected to also advance ZBLAN:Yb3+ to sub-TEC temperatures. However, recent achievements with YLF:Yb3+ illustrate that crystalline materials may have two potentially game-changing advantajes over glassy materials. First, the crystalline environment reduces the inhomogeneous broadening of the Yb3+ electronic transitions as compared to a glassy matrix. The respective sharpening of the crystal-field transitions increases the peak absorption cross section at the laser excitation wavelength and allows for more efficient pumping of the Yb3+ ions, particularly at low temperatures. Second, many detrimental impurities present in the starting materials tend to be excluded from the crystal during its slow growth process, in contrast to a glass where all impurities present in the starting materials are included in the glass when it is formed by temperature quenching a melt. The ultra high purity required for laser cooling materials [PRB] therefore may be easier to realize in crystals than in glasses. Laser cooling occurs by laser excitation of a rare-earth ion followed by anti-Stokes luminescence. Each such laser-cooling cycle extracts

  19. Preparation of QP4VP-b-LCP liquid crystal block copolymer and its application as a biosensor.

    PubMed

    Omer, Muhammad; Park, Soo-Young

    2014-09-01

    The interface between nematic liquid crystal, 4-cyano-4'-pentylbiphenyl (5CB), and water in a transmission electron microscopy (TEM) grid cell coated with QP4VP-b-LCP (quaternized poly(4-vinylpyridine) (QP4VP) and poly(4-cyanobiphenyl-4'-oxyundecylacrylate) (LCP)) was examined for protein and DNA detection. QP4VP-b-LCP was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Quaternization of P4VP with iodomethane (CH3I) made it a strong cationic polyelectrolyte and allowed QP4VP-b-LCP to form complexes with oppositely charged biological species. Several proteins, such as bovine serum albumin (BSA), hemoglobin (Hb), α chymotrypsinogen-A (ChTg), and lysozyme (LYZ), were tested for nonspecific protein detection. By injecting the protein solutions into the TEM grid cell, the initial homeotropic orientation of the TEM grid cell changed to a planar orientation above their isoelectric points (PIs) due to electrostatic interactions between QP4VP (+charge) and proteins (-charge), which did not occur below the PIs of the tested proteins. Their minimum concentrations at which the homeotropic to planar configurational change (H-P change) occurred were 0.01, 0.02, 0.03, and 0.04 wt.% for BSA, ChTg, Hb, and LYZ, respectively. One of the strong anionic polyelectrolytes, deoxyribonucleic acid (DNA) (due to the phosphate deoxyribose backbone) was also tested. A H-P change was observed with as little as 0.0013 wt.% salmon sperm DNA regardless of the pH of the cell. A H-P change occurred in 5CB and was observed by polarized optical microscopy. This simple and inexpensive setup for nonspecific biomaterial detection provides the basic idea for developing effective selective biosensors by introducing specific binding groups, such as the aptamer and antibody. PMID:24980600

  20. Nonlinear waveguide optics and photonic crystal fibers.

    PubMed

    Knight, J C; Skryabin, D V

    2007-11-12

    Focus Serial: Frontiers of Nonlinear Optics

    Optical fibers and waveguides provide unique and distinct environments for nonlinear optics, because of the combination of high intensities, long interaction lengths, and control of the propagation constants. They are also becoming of technological importance. The topic has a long history but continues to generate rapid development, most recently through the invention of the new forms of optical fiber collectively known as photonic crystal fibers. Some of the discoveries and ideas from the new fibers look set to have lasting influence in the broader field of guided-wave nonlinear optics. In this paper we introduce some of these ideas. PMID:19550822

  1. Optical solitons in liquid crystals

    SciTech Connect

    Yung, Y.S.; Lam, L.; Los Alamos National Lab., NM )

    1989-01-01

    In this paper, we will discuss theoretically the possible existence of optical solitons in the isotropic liquid and in the nematic phase. For the same compound, when heated, the nematic phase will go through a first order transition at temperature T{sub c} to the isotropic liquid phase. As temperature increases from below T{sub c}, the orientation order parameter, Q, decreases, drops to zero abruptly at T{sub c} and remains zero for T > T{sub c}. 10 refs., 1 fig.

  2. Nanostructured porous Si optical biosensors: effect of thermal oxidation on their performance and properties.

    PubMed

    Shtenberg, Giorgi; Massad-Ivanir, Naama; Fruk, Ljiljana; Segal, Ester

    2014-09-24

    The influence of thermal oxidation conditions on the performance of porous Si optical biosensors used for label-free and real-time monitoring of enzymatic activity is studied. We compare three oxidation temperatures (400, 600, and 800 °C) and their effect on the enzyme immobilization efficiency and the intrinsic stability of the resulting oxidized porous Si (PSiO2), Fabry-Pérot thin films. Importantly, we show that the thermal oxidation profoundly affects the biosensing performance in terms of greater optical sensitivity, by monitoring the catalytic activity of horseradish peroxidase and trypsin-immobilized PSiO2. Despite the significant decrease in porous volume and specific surface area (confirmed by nitrogen gas adsorption-desorption studies) with elevating the oxidation temperature, higher content and surface coverage of the immobilized enzymes is attained. This in turn leads to greater optical stability and sensitivity of PSiO2 nanostructures. Specifically, films produced at 800 °C exhibit stable optical readout in aqueous buffers combined with superior biosensing performance. Thus, by proper control of the oxide layer formation, we can eliminate the aging effect, thus achieving efficient immobilization of different biomolecules, optical signal stability, and sensitivity. PMID:25159537

  3. Microplate based optical biosensor for L-Dopa using tyrosinase from Amorphophallus campanulatus.

    PubMed

    Saini, Amardeep Singh; Kumar, Jitendra; Melo, Jose Savio

    2014-11-01

    Developing a biosensor which is capable of simultaneously monitoring l-Dopa levels in multiple samples besides requiring small reaction volume is of great value. The present study describes the detection of l-Dopa using tyrosinase enzyme extracted from Amorphophallus campanulatus and immobilized on the surface of the microplate wells. Among the different approaches used for immobilizing tyrosinase onto the microplate wells, glutaraldehyde treatment was found to be most effective. Besides enzyme activity, ESEM-EDS (environmental scanning electron microscope-energy dispersive system) and Atomic Force Microscopy (AFM) were also carried out to confirm the immobilization of tyrosinase enzyme onto the microplate well surface. This immobilized biocomponent was then integrated with an optical transducer for l-Dopa detection and it showed good reproducibility. The sensing property of the system was studied by measuring the initial rate of dopachrome formation at 475 nm. The calibration plot gave a linear range of detection from 10-1000 μM and the detection limit was calculated to be 3 μM. The immobilized biocomponent was stable for 41 days and was reused up to nine times. Spiked samples (blood plasma) were also analyzed using this biocomponent. This microplate based biosensor thus provides a convenient system for detection of multiple samples in a single run. PMID:25300217

  4. Fabrication of Refractive Index Tunable Polydimethylsiloxane Photonic Crystal for Biosensor Application

    NASA Astrophysics Data System (ADS)

    Raman, Karthik; Murthy, T. R. Srinivasa; Hegde, G. M.

    Photonic crystal based nanostructures are expected to play a significant role in next generation nanophotonic devices. Recent developments in two-dimensional (2D) photonic crystal based devices have created widespread interest as such planar photonic structures are compatible with conventional microelectronic and photonic devices. Various optical components such as waveguides, resonators, modulators and demultiplexers have been designed and fabricated based on 2D photonic crystal geometry. This paper presents the fabrication of refractive index tunable Polydimethylsiloxane (PDMS) polymer based photonic crystals. The advantages of using PDMS are mainly its chemical stability, bio-compatibility and the stack reduces sidewall roughness scattering. The PDMS structure with square lattice was fabricated by using silicon substrate patterned with SU8-2002 resist. The 600 nm period grating of PDMS is then fabricated using Nano-imprinting. In addition, the refractive index of PDMS is modified using certain additive materials. The resulting photonic crystals are suitable for application in photonic integrated circuits and biological applications such as filters, cavities or microlaser waveguides.

  5. Optical mirage in graded photonic crystals

    NASA Astrophysics Data System (ADS)

    Centeno, Emmanuel; Cassagne, David; Albert, Jean Paul

    2006-04-01

    We present the concept of graded photonic crystals (GPC) and show its ability to enhance the control of light propagation. It is shown that gradual modifications of photonic crystal parameters are able to curve the path of light. This light bending which depends on the wavelength and on the incident angle is examined through parametric studies of the iso-frequency curves. We demonstrate that photonic mirages originate from the same physical principles as the usual atmospheric mirages. Two optical components based on two-dimensional GPCs presenting a super bending effect and a large beam shifting are presented.

  6. Optical amplification enhancement in photonic crystals

    SciTech Connect

    Sapienza, R.; Leonetti, M.; Froufe-Perez, L. S.; Galisteo-Lopez, J. F.; Lopez, C.; Conti, C.

    2011-02-15

    Improving and controlling the efficiency of a gain medium is one of the most challenging problems of laser research. By measuring the gain length in an opal-based photonic crystal doped with laser dye, we demonstrate that optical amplification is more than twenty-fold enhanced along the {Gamma}-K symmetry directions of the face-centered-cubic photonic crystal. These results are theoretically explained by directional variations of the density of states, providing a quantitative connection between density of the states and light amplification.

  7. Microalgae dual-head biosensors for selective detection of herbicides with fiber-optic luminescent O2 transduction.

    PubMed

    Haigh-Flórez, David; de la Hera, Cristina; Costas, Eduardo; Orellana, Guillermo

    2014-04-15

    The microalgal species Dictyosphaerium chlorelloides (D. c.) was immobilized into porous silicone films and their photosynthetic activity was monitored with an integrated robust luminescent O2 sensor. The biosensor specificity towards a particular pesticide has been achieved by manufacturing a fiber-optic dual-head device containing both analyte-sensitive and analyte-resistant D. c. strains. The latter are not genetically modified microalgae, but a product of modified Luria-Delbrück fluctuation analysis followed by ratchet selection cycles. In this way the target herbicide decreases the O2 production of the analyte-sensitive immobilized strain without affecting the analyte-resistant population response; any other pollutant will lower the O2 production of both strains. The effect of the sample flow-rate, exposure time to the herbicide, biomass loading, biosensor film thickness, intensity of the actinic light, illumination cycle, and temperature on the biosensor response has been evaluated using waterborne simazine as test bench. The biosensing device is able to provide in situ measurements of the herbicide concentration every 180 min. The biosensor limit of detection for this herbicide was 12 μg L(-1), with a working range of 50-800 μg L(-1). The biosensor specificity to simazine has been assessed by comparing its response to that of isoproturon. PMID:24316451

  8. Optical fiber direct-sensing biosensor applied in detecting biolayer thickness of nanometer grade

    NASA Astrophysics Data System (ADS)

    Sun, Yan; Li, Mingming; Zhao, Hong; Yang, Yu Xiao; Zhang, Lu

    2006-02-01

    An optical fiber biosensor is introduced herein, which could directly detect biological interaction such as immunoreactions of antigens and antibodies without destroy the biolayer. The test is based on the theory of multilayer-reflection principle in white-light interferometry. When immunoreactions occur, the reflected spectrum phase shifts. Immunoreactions could be detected by means of reflected spectrum phase shifting, or by biolayer thickness changing. Continuously detecting of thickness changing on a fractional nanometer scale with subsecond repetition times is allowed in this system. The detecting system has high sensitivity, high precision, high speed, cost effective and working on a high reliability. The bioprobe is easy integrated as a BlAcore. The system and the experimental results on the reaction of rabbit-IgG with anti-rabbit-IgG are described in this paper. A sandwich method was adopted in the experiments.

  9. 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.

  10. Measuring binding kinetics of biomolecular interactions using a localized surface plasmon couple fluorescence fiber optic biosensor

    NASA Astrophysics Data System (ADS)

    Chang, Ying-Feng; Hsieh, Jo-Ping; Su, Li-Chen; Li, Ying-Chang; Lee, Cheng-Chung; Chou, Chien

    2010-08-01

    In this study, we describe a novel method for analyzing protein-protein binding kinetics at ultra-low concentration (1 pg/mL) using a localized surface plasmon coupled fluorescence fiber-optic biosensor (LSPCF-FOB). The association and dissociation rate constants, ka and kd, respectively, for the binding kinetics of the mouse IgG/ anti-mouse IgG interaction have been calculated to be ka = (5.9928+/-3.1540)x106 M-1s-1 and kd = (1.0587+/-0.5572)x10-3 s-1. The theoretical basis of this analytical approach is a rapid-mixing model integrated with a two-compartment model; has been experimentally verified in this study as well. The LSPCF-FOB provides a potentially alternative option for characterizing the interaction of biomolecules at ultra-low concentrations.

  11. Optical Restoration of Lead Fluoride Crystals

    SciTech Connect

    Spilker, A.; Cole, P. L.; Forest, T. A.; Mestari, M.; Naeem, S.; LeBaron, N.; Bertin, P.; Camacho, C. Munoz; Roche, J.

    2009-03-10

    Due to its relatively high resistance to high radiation, lead fluoride (PbF{sub 2}) crystals are becoming an increasingly popular material of choice for electromagnetic calorimetry, such as for experiments requiring the measurement of high-energy photons in Hall A of Jefferson Lab. For our studies we irradiated the PbF{sub 2} crystals using an electron linear accelerator (LINAC) followed by exposing the crystals to blue light so as to restore the nominal optical properties. This technique of optical bleaching with blue light affords an efficient and low-cost means for reversing the deleterious effects of optical transmission loss in radiation-damaged lead fluoride crystals. Whereas earlier experiments irradiated the PbF{sub 2} samples with 1.1 and 1.3 MeV gammas from {sup 60}Co, we used pulsed beams of energetic electrons from the tunable 25-MeV LINAC at Idaho Accelerator Center of Idaho State University in Pocatello, Idaho. A 20-MeV beam of electrons was targeted onto four separate 19 cm length samples of lead fluoride over periods of 1, 2, and 4 hours yielding doses between 7 kGy and 35 kGy. Samples were then bleached with blue light of wavelength 410-450 nm for periods between 19.5 and 24 hours. We performed this process twice - radiation, bleaching, radiation, and then followed by bleaching again - for each of these four PbF{sub 2} samples. We shall discuss the efficacy of blue light curing on samples that have undergone two cycles of electron irradiation and optical bleaching.

  12. Solitonic optical waveguides in PR crystals

    NASA Astrophysics Data System (ADS)

    Klotz, Matthew Jason

    This dissertation describes a new technique for creating permanent, two-dimensional optical circuitry in bulk ferroelectric photorefractive crystals. This method utilizes steady state photorefractive screening spatial solitons to produce a localized space charge field capable of modulating the spontaneous polarization of the ferroelectric crystal. This localized change in the spontaneous polarization results in a permanent index change within the material that is capable of guiding optical waves. Individual waveguides were formed in the crystal by fixing single screening solitons. The waveguides were found to be identical in size to the soliton responsible for their formation and were observed to efficiently guide light for periods of continuous illumination in excess of 12 hours without degradation. In addition, arrays of waveguides were formed using binary optics to form several solitons in the material at the same time. It was determined that waveguides formed by extraordinarily polarized solitons were single mode and that those formed by ordinarily polarized solitons were multimode, due to the difference in the magnitude of the nonlinear optical properties of the crystal for the different polarization states. Thus the size and mode guiding properties of the fixed waveguides can be controlled by changing the input solitons properties. In addition to single waveguides formed by a single screening soliton, coherent collisions of two screening solitons were used to form a permanent y-junction in the crystal. The screening soliton collision results in two initially independent solitons fusing into a single soliton. After fixing, the resulting waveguide structure allows signals from two distinct inputs to be combined into a single output. It was demonstrated that this fixed structure was bidirectional, i.e. that light sent into the output would exit the original input branches with an even division of power. Again, the size and mode guiding properties were found to

  13. Liquid crystals for holographic optical data storage.

    PubMed

    Matharu, Avtar S; Jeeva, Shehzad; Ramanujam, P S

    2007-12-01

    A tutorial review is presented to inform and inspire the reader to develop and integrate strong scientific links between liquid crystals and holographic data storage, from a materials scientist's viewpoint. The principle of holographic data storage as a means of providing a solution to the information storage demands of the 21st century is detailed. Holography is a small subset of the much larger field of optical data storage and similarly, the diversity of materials used for optical data storage is enormous. The theory of polarisation holography which produces holograms of constant intensity, is discussed. Polymeric liquid crystals play an important role in the development of materials for holographic storage and photoresponsive materials based on azobenzene are targeted for discussion due to their ease of photo-reversion between trans- and cis-states. Although the final polymer may not be liquid crystalline, irradiation can induce ordered domains. The mesogens act in a co-operative manner, enhancing refractive indices and birefringences. Surface relief gratings are discussed as a consequence of holographic storage. Cholesteric polymers comprising azobenzene are briefly highlighted. Irradiation causing cis-trans-isomerisation can be used to control helix pitch. A brief mention of liquid crystals is also made since these materials may be of future interest since they are optically transparent and amenable to photo-induced anisotropy. PMID:17982514

  14. Optical biosensor with poly[N-nonyl-3,6-bis(ethylenedioxythiophene)carbazole] matrix for monitoring of phenol derivatives

    NASA Astrophysics Data System (ADS)

    Jedrychowska, Agnieszka; Malecha, Karol; Cabaj, Joanna; Sołoducho, Jadwiga

    2014-08-01

    The aim of the research was to develop an enzymatic, optical biosensor which provides quick and convenient determination of phenolic compounds in aqueous solutions. The biosensing strategy concerns design, fabrication and testing of a miniature ceramic-based biosensor which is destined for in-situ substrate monitoring. The base of the measuring system was fabricated using low temperature co-fired ceramics (LTCC) technology. The biocatalyst - laccase- was immobilized on the thin film of poly[N-nonyl-3,6-bis(ethylenedioxythiophene)carbazole] which provided good binding of the enzyme to the substrate and positively affected on the catalytic activity of the protein. In order to evaluate properties of the designed biosensor, its response for various concentrations of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diamonnium sal (ABTS) was measured. The optical biosensor produced by presented method could find applications in many fields, i.e. for detection of phenolic compounds in food products and beverages, in industry for control of technological processes or for environmental monitoring

  15. Sensitivity control of optical fiber biosensors utilizing turnaround point long period gratings with self-assembled polymer coatings

    NASA Astrophysics Data System (ADS)

    Gifford, Erika; Wang, Z.; Ramachandran, S.; Heflin, J. R.

    2007-09-01

    Ionic self-assembled multilayers (ISAMs) adsorbed on long period fiber gratings (LPGs) can serve as an inexpensive, robust, portable, biosensor platform. The ISAM technique is a layer-by-layer deposition technique that creates thin films on the nanoscale level. The combination of ISAMs with LPGs yields exceptional sensitivity of the optical fiber transmission spectrum. We have shown theoretically that the resonant wavelength shift for a thin-film coated LPG can be caused by the variation of the film's refractive index and/or the variation of the thickness of the film. We have experimentally demonstrated that the deposition of nm-thick ISAM films on LPGs induces shifts in the resonant wavelength of > 1.6 nm per nm of thin film. It has also been shown that the sensitivity of the LPG to the thickness of the ISAM film increases with increased film thickness. We have further demonstrated that ISAM-coated LPGs can function effectively as biosensors by using the biotin-streptavidin system and by using the Bacillus anthracis (Anthrax) antibody- PA (Protective Antigen) system. Experiments have been successfully performed in both air and solution, which illustrates the versatility of the biosensor. The results confirm that ISAM-LPGs yield a reusable, thermally-stable, and robust platform for designing and building efficient optical biosensors.

  16. Use of Label-free Optical Biosensors to Detect Modulation of Potassium Channels by G-protein Coupled Receptors

    PubMed Central

    Fleming, Matthew R.; Shamah, Steven M.; Kaczmarek, Leonard K.

    2014-01-01

    Ion channels control the electrical properties of neurons and other excitable cell types by selectively allowing ions to flow through the plasma membrane1. To regulate neuronal excitability, the biophysical properties of ion channels are modified by signaling proteins and molecules, which often bind to the channels themselves to form a heteromeric channel complex2,3. Traditional assays examining the interaction between channels and regulatory proteins require exogenous labels that can potentially alter the protein's behavior and decrease the physiological relevance of the target, while providing little information on the time course of interactions in living cells. Optical biosensors, such as the X-BODY Biosciences BIND Scanner system, use a novel label-free technology, resonance wavelength grating (RWG) optical biosensors, to detect changes in resonant reflected light near the biosensor. This assay allows the detection of the relative change in mass within the bottom portion of living cells adherent to the biosensor surface resulting from ligand induced changes in cell adhesion and spreading, toxicity, proliferation, and changes in protein-protein interactions near the plasma membrane. RWG optical biosensors have been used to detect changes in mass near the plasma membrane of cells following activation of G protein-coupled receptors (GPCRs), receptor tyrosine kinases, and other cell surface receptors. Ligand-induced changes in ion channel-protein interactions can also be studied using this assay. In this paper, we will describe the experimental procedure used to detect the modulation of Slack-B sodium-activated potassium (KNa) channels by GPCRs. PMID:24562095

  17. Multiscattering-enhanced optical biosensor: multiplexed, non-invasive and continuous measurements of cellular processes

    PubMed Central

    Koman, Volodymyr B.; Santschi, Christian; Martin, Olivier J. F.

    2015-01-01

    The continuous measurement of uptake or release of biomarkers provides invaluable information for understanding and monitoring the metabolism of cells. In this work, a multiscattering-enhanced optical biosensor for the multiplexed, non-invasive, and continuous detection of hydrogen peroxide (H2O2), lactate and glucose is presented. The sensing scheme is based on optical monitoring of the oxidation state of the metalloprotein cytochrome c (cyt c). The analyte of interest is enzymatically converted into H2O2 leading to an oxidation of the cyt c. Contact microspotting is used to prepare nanoliter-sized sensing spots containing either pure cyt c, a mixture of cyt c with glucose oxidase (GOx) to detect glucose, or a mixture of cyt c with lactate oxidase (LOx) to detect lactate. The sensing spots are embedded in a multiscattering porous medium that enhances the optical signal. We achieve limits of detection down to 240 nM and 110 nM for lactate and glucose, respectively. A microfluidic embodiment enables multiplexed and crosstalk-free experiments on living organisms. As an example, we study the uptake of exogenously supplied glucose by the green algae Chlamydomonas reinhardtii and simultaneously monitor the stress-related generation of H2O2. This multifunctional detection scheme provides a powerful tool to study biochemical processes at cellular level. PMID:26203366

  18. Multiscattering-enhanced optical biosensor: multiplexed, non-invasive and continuous measurements of cellular processes.

    PubMed

    Koman, Volodymyr B; Santschi, Christian; Martin, Olivier J F

    2015-07-01

    The continuous measurement of uptake or release of biomarkers provides invaluable information for understanding and monitoring the metabolism of cells. In this work, a multiscattering-enhanced optical biosensor for the multiplexed, non-invasive, and continuous detection of hydrogen peroxide (H2O2), lactate and glucose is presented. The sensing scheme is based on optical monitoring of the oxidation state of the metalloprotein cytochrome c (cyt c). The analyte of interest is enzymatically converted into H2O2 leading to an oxidation of the cyt c. Contact microspotting is used to prepare nanoliter-sized sensing spots containing either pure cyt c, a mixture of cyt c with glucose oxidase (GOx) to detect glucose, or a mixture of cyt c with lactate oxidase (LOx) to detect lactate. The sensing spots are embedded in a multiscattering porous medium that enhances the optical signal. We achieve limits of detection down to 240 nM and 110 nM for lactate and glucose, respectively. A microfluidic embodiment enables multiplexed and crosstalk-free experiments on living organisms. As an example, we study the uptake of exogenously supplied glucose by the green algae Chlamydomonas reinhardtii and simultaneously monitor the stress-related generation of H2O2. This multifunctional detection scheme provides a powerful tool to study biochemical processes at cellular level. PMID:26203366

  19. Thermally Engineered Blue Photoluminescence of Porous Anodic Alumina Membranes for Promising Optical Biosensors

    NASA Astrophysics Data System (ADS)

    Bu, Sang Don; Cho, Sam Yeon; Choi, Yong Chan; Kim, Jin Woo; Han, Jin Kyu; Kwak, Jin Ho; Yang, Sun A.

    Optical biosensors based on porous anodic alumina membranes (PAAMs) have shown to be an effective device because of their unique optical properties and biocompatibility. Among various optical properties, photoluminescence (PL) emission derived from PAAMs is one of the most suitable characteristics. However, the origin of PL from PAA is unclear and still in doubt. Therefore, it is essential for further potential practical applications to understand the origin of PL and PL variations. Here, we investigate the effects of post-annealing temperatures on the blue PL of amorphous PAAMs fabricated in oxalic acid. We find that the blue PL emission is strongly dependent on the thermal properties. A strong blue PL at a peak of ~460 nm is observed from the initial PAAM (not annealed PAAM) and this PL band can be divided into two Gaussian components at 458 ~ +/- ~ 4 nm (P1 band) and 517 ~ +/- 7nm (P2 band). As the temperature increases to 600 ° C , the intensities of two PL bands gradually increase. During temperature increases from 600 to 700 ° C , the P2 band increases but the P1 band decreases. The analyses of electron paramagnetic resonance, Fourier transform infrared spectroscopy, and ultraviolet-visible absorption spectroscopy show that the P1 and P2 bands originate from the unstable carboxylates and the stable carboxylates, respectively.

  20. DNA aptamer-based fiber optic biosensor for selective and label-free detection of dopamine

    NASA Astrophysics Data System (ADS)

    Zibaii, M. I.; Latifi, H.; Asadollahi, A.; Bayat, A. H.; Haghparast, A.

    2015-09-01

    Dopamine (DA) analysis is complicated by the interference from other electrochemically active endogenous compounds present in the brain, including DA precursors and metabolites and other neurotransmitters (NT). Here we report a simple, sensitive and selective optical fiber biosensor for the detection of DA in the presence of other NT. It is composed of a 57-mer dopamine-binding aptamer (DBA) as recognition element and nonadiabatic tapered optical fiber (NATOF) as probe. Upon the addition of DA, the conformation of DBA would change from a random coil structure to a rigid tertiary structure like a pocket. The conformational change of DBA lead to the refractive index (RI) change around the tapered fiber surface. Specific recognition of DA by the aptamer allowed a selective optical detection of DA within the physiologically relevant 500 nM to 10 μM range. Some common interferents such as epinephrine (EP) and ascorbic acid (AA) showed no or just a little interference in the determination of DA.

  1. Submicron diameter single crystal sapphire optical fiber

    SciTech Connect

    Hill, Cary; Homa, Daniel; Liu, Bo; Yu, Zhihao; Wang, Anbo; Pickrell, Gary

    2014-10-02

    In this work, a submicron-diameter single crystal sapphire optical fiber was demonstrated via wet acid etching at elevated temperatures. Etch rates on the order 2.3 µm/hr were achievable with a 3:1 molar ratio sulfuric-phosphoric acid solution maintained at a temperature of 343°C. A sapphire fiber with an approximate diameter of 800 nm was successfully fabricated from a commercially available fiber with an original diameter of 50 µm. The simple and controllable etching technique provides a feasible approach to the fabrication of unique waveguide structures via traditional silica masking techniques. The ability to tailor the geometry of sapphire optical fibers is the first step in achieving optical and sensing performance on par with its fused silica counterpart.

  2. Submicron diameter single crystal sapphire optical fiber

    DOE PAGESBeta

    Hill, Cary; Homa, Daniel; Liu, Bo; Yu, Zhihao; Wang, Anbo; Pickrell, Gary

    2014-10-02

    In this work, a submicron-diameter single crystal sapphire optical fiber was demonstrated via wet acid etching at elevated temperatures. Etch rates on the order 2.3 µm/hr were achievable with a 3:1 molar ratio sulfuric-phosphoric acid solution maintained at a temperature of 343°C. A sapphire fiber with an approximate diameter of 800 nm was successfully fabricated from a commercially available fiber with an original diameter of 50 µm. The simple and controllable etching technique provides a feasible approach to the fabrication of unique waveguide structures via traditional silica masking techniques. The ability to tailor the geometry of sapphire optical fibers ismore » the first step in achieving optical and sensing performance on par with its fused silica counterpart.« less

  3. Optics in Microstructured and Photonic Crystal Fibers

    NASA Astrophysics Data System (ADS)

    Knight, J. C.

    2008-10-01

    The development of optical fibers with two-dimensional patterns of air holes running down their length has reinvigorated research in the field of fiber optics. It has greatly—and fundamentally—broadened the range of specialty optical fibers, by demonstrating that optical fibers can be more "special" than previously thought. Fibers with air cores have made it possible to deliver energetic femtosecond-scale optical pulses, transform limited, as solitons, using single-mode fiber. Other fibers with anomalous dispersion at visible wavelengths have spawned a new generation of single-mode optical supercontinuum sources, spanning visible and near-infrared wavelengths and based on compact pump sources. A third example is in the field of fiber lasers, where the use of photonic crystal fiber concepts has led to a new hybrid laser technology, in which the very high numerical aperture available sing air holes have enabled fibers so short they are more naturally held straight than bent. This paper describes some of the basic physics and technology behind these developments, illustrated with some of the impressive demonstrations of the past 18 months.

  4. Plastic optical fiber-based biosensor platform for rapid cell detection.

    PubMed

    Wandermur, Gisele; Rodrigues, Domingos; Allil, Regina; Queiroz, Vanessa; Peixoto, Raquel; Werneck, Marcelo; Miguel, Marco

    2014-04-15

    This work presents a novel, fast response time, plastic optic fiber (POF) biosensor to detect Escherichia coli. It discloses the technique for the development, calibration and measurement of this robust and simple-to-construct POF biosensor. The probes in U-shaped format were manufactured with a specially developed device. The calibration process led to the evaluation of the sensitivity, accuracy and repeatability by using solutions of sucrose for obtaining refractive indices (RI) in the range 1.33-1.39 IR equivalent of water and bacteria, respectively. The POF probes were functionalized with antibody anti-E. coli serotype O55 and tested firstly with saline and then with bacterial concentrations of 10(4), 10(6), and 10(8) colony forming units/ml (CFU/ml). The optoelectronic setup consists of an 880 nm LED connected to the U-shaped probe driven by a sine waveform generated by the Simulink (from Matlab(®)). On the other side of the probe a photodetector generates a photocurrent which is amplified by a transconductance amplifier. The output voltage signal is read by the analog-to-digital (A/D) input of the microcontroller. In all tested concentrations, the results presented a tendency of a decrease in the output signal with time, due to the attachment of the bacteria to the POF probe and consequent increase in the RI close to the sensitive area of the fiber surface. It has been shown that the system is capable of providing positive response to the bacterial concentration in less than 10 min, demonstrating good possibilities to be commercially developed as a portable field sensor. PMID:24334281

  5. Optically optimized photoluminescent and interferometric biosensors based on nanoporous anodic alumina: a comparison.

    PubMed

    Santos, Abel; Kumeria, Tushar; Losic, Dusan

    2013-08-20

    Herein, we present a comparative study about the sensing performance of optical biosensors based on photoluminescence spectroscopy (PLS) and reflectometric interference spectroscopy (RIfS) combined with nanoporous anodic alumina (NAA) platforms when detecting different analytes under distinct adsorption conditions. First, NAA platforms are structurally engineered in order for optimizing the optical signals obtained by PLS and RIfS. Then, the most optimal NAA platforms combined with PLS and RIfS are quantitatively compared by detecting two different analytes: d-glucose and l-cysteine under nonspecific and specific adsorption conditions, respectively. The obtained results demonstrate that such parameters as the analyte nature and adsorption conditions play a direct role in the sensing performance of these platforms. However, as this study demonstrates, PLS-NAA platforms are more sensitive than RIfS-NAA ones. The former shows better linearity (i.e., proportional change in the sensing parameter with analyte concentration), higher sensitivity toward analytes (i.e., sharper change in the sensing parameter with analyte concentration), and lower limit of detection (i.e., minimum detectable concentration of analyte). PMID:23862775

  6. Flow injection analysis with bioluminescence-based fiber-optic biosensors

    NASA Astrophysics Data System (ADS)

    Blum, Loic J.; Gautier, Sabine; Coulet, Pierre R.

    1991-09-01

    Fiber optic biosensors based on the firefly and the bacterial bioluminescence reactions have been constructed and incorporated in a specially designed flow-cell for the sensitive determination of ATP and NADH, respectively. The bioluminescence enzymes were immobilized on preactivated polyamide membranes which were placed in close contact with the surface on one end of a glass-fiber bundle, the other end being connected to the photomultiplier tube of a luminometer. When using the continuous-flow device with the firefly luciferase or the bacterial system immobilized separately on different membranes, the detection limit for ATP and NADH were 0.25 and 2 pmol, respectively. The versatility of the fiber optic probe has been improved by co-immobilizing the bacterial bioluminescent system and the firefly luciferase on the same support enabling the use of a single sensor for the selective, specific, and alternate determination of these two analytes. Compatible reaction conditions preserving the activity of each co-immobilized enzyme without impairing its stability were found. The selection of the appropriate reaction medium was done using a four port valve. Alternate quantification of ATP and NADH could then be performed in the linear ranges 0.25 pmol - 3 nmol and 5 pmol - 1 nmol, respectively with a RSD of 4.0 - 4.5%.

  7. Water quality monitoring using an automated portable fiber optic biosensor: RAPTOR

    NASA Astrophysics Data System (ADS)

    Anderson, George P.; Rowe-Taitt, Chris A.

    2001-03-01

    The RAPTOR is a portable, automated biosensor capable of performing rapid, ten-minute assays on a sample for four target analytes simultaneously. Samples are analyzed using a fluorescent sandwich immunoassay on the surface of short polystyrene optical probes with capture antibody adsorbed to the probe surface. Target analytes bound to the fiber by capture antibodies are detected with fluorescently labeled tracer antibodies, which are held in a separate reservoir. Since target recognition is a two-step process, selectivity is enhanced, and the optical probes can be reused up to forty times, or until a positive result is obtained. This greatly reduces the logistical burden for field operations. Numerous assays for toxins, such as SEB and ricin, and bacteria, such as Bacillus anthracis and Francisella tularensis, have been developed for the RAPTOR. An assay of particular interest for water quality monitoring and the screening of fruits and vegetables is detection of Giardia cysts. Giardia lamblia is a parasitic protozoan common in the developing world that causes severe intestinal infections. Thus, a simple field assay for screening water supplies would be highly useful. Such an assay has been developed using the RAPTOR. The detection limit for Giardia cysts was 5x104/ml for a 10-minute assay.

  8. Optical biosensor technologies for molecular diagnostics at the point-of-care

    NASA Astrophysics Data System (ADS)

    Schotter, Joerg; Schrittwieser, Stefan; Muellner, Paul; Melnik, Eva; Hainberger, Rainer; Koppitsch, Guenther; Schrank, Franz; Soulantika, Katerina; Lentijo-Mozo, Sergio; Pelaz, Beatriz; Parak, Wolfgang; Ludwig, Frank; Dieckhoff, Jan

    2015-05-01

    Label-free optical schemes for molecular biosensing hold a strong promise for point-of-care applications in medical research and diagnostics. Apart from diagnostic requirements in terms of sensitivity, specificity, and multiplexing capability, also other aspects such as ease of use and manufacturability have to be considered in order to pave the way to a practical implementation. We present integrated optical waveguide as well as magnetic nanoparticle based molecular biosensor concepts that address these aspects. The integrated optical waveguide devices are based on low-loss photonic wires made of silicon nitride deposited by a CMOS compatible plasma-enhanced chemical vapor deposition (PECVD) process that allows for backend integration of waveguides on optoelectronic CMOS chips. The molecular detection principle relies on evanescent wave sensing in the 0.85 μm wavelength regime by means of Mach-Zehnder interferometers, which enables on-chip integration of silicon photodiodes and, thus, the realization of system-on-chip solutions. Our nanoparticle-based approach is based on optical observation of the dynamic response of functionalized magneticcore/ noble-metal-shell nanorods (`nanoprobes') to an externally applied time-varying magnetic field. As target molecules specifically bind to the surface of the nanoprobes, the observed dynamics of the nanoprobes changes, and the concentration of target molecules in the sample solution can be quantified. This approach is suitable for dynamic real-time measurements and only requires minimal sample preparation, thus presenting a highly promising point-of-care diagnostic system. In this paper, we present a prototype of a diagnostic device suitable for highly automated sample analysis by our nanoparticle-based approach.

  9. Microstructured Optical Fiber-based Biosensors: Reversible and Nanoliter-Scale Measurement of Zinc Ions.

    PubMed

    Heng, Sabrina; McDevitt, Christopher A; Kostecki, Roman; Morey, Jacqueline R; Eijkelkamp, Bart A; Ebendorff-Heidepriem, Heike; Monro, Tanya M; Abell, Andrew D

    2016-05-25

    Sensing platforms that allow rapid and efficient detection of metal ions would have applications in disease diagnosis and study, as well as environmental sensing. Here, we report the first microstructured optical fiber-based biosensor for the reversible and nanoliter-scale measurement of metal ions. Specifically, a photoswitchable spiropyran Zn(2+) sensor is incorporated within the microenvironment of a liposome attached to microstructured optical fibers (exposed-core and suspended-core microstructured optical fibers). Both fiber-based platforms retains high selectivity of ion binding associated with a small molecule sensor, while also allowing nanoliter volume sampling and on/off switching. We have demonstrated that multiple measurements can be made on a single sample without the need to change the sensor. The ability of the new sensing platform to sense Zn(2+) in pleural lavage and nasopharynx of mice was compared to that of established ion sensing methodologies such as inductively coupled plasma mass spectrometry (ICP-MS) and a commercially available fluorophore (Fluozin-3), where the optical-fiber-based sensor provides a significant advantage in that it allows the use of nanoliter (nL) sampling when compared to ICP-MS (mL) and FluoZin-3 (μL). This work paves the way to a generic approach for developing surface-based ion sensors using a range of sensor molecules, which can be attached to a surface without the need for its chemical modification and presents an opportunity for the development of new and highly specific ion sensors for real time sensing applications. PMID:27152578

  10. Modal liquid crystal array of optical elements.

    PubMed

    Algorri, J F; Love, G D; Urruchi, V

    2013-10-21

    In this study, a novel liquid crystal array based on modal control principle is proposed and demonstrated. The advanced device comprises a six striped electrode structure that forms a configurable 2D matrix of optical elements. A simulation program based on the Frank-Oseen equations and modal control theory has been developed to predict the device electrooptic response, that is, voltage distribution, interference pattern and unwrapped phase. A low-power electronics circuit, that generates complex waveforms, has been built for driving the device. A combined variation of the waveform amplitude and phase has provided a high tuning versatility to the device. Thus, the simulations have demonstrated the generation of a liquid crystal prism array with tunable slope. The proposed device has also been configured as an axicon array. Test measurements have allowed us to demonstrate that electrooptic responses, simulated and empirical, are fairly in agreement. PMID:24150324

  11. Wide Angle Liquid Crystal Optical Phased Array

    NASA Technical Reports Server (NTRS)

    Wang, Xing-Hua; Wang, Bin; Bos, Philip J.; Anderson, James E.; Pouch, John J.; Miranda, Felix A.; McManamon, Paul F.

    2004-01-01

    Accurate modeling of a high resolution, liquid crystal (LC) based, optical phased array (OPA) is shown. The simulation shows excellent agreement with a test 2-D LC OPA. The modeling method is extendable to cases where the array element size is close to the wavelength of light. The fringing fields of such a device are first studied, and subsequently reduced. This results in a device that demonstrates plus or minus 7.4 degrees of continuous beam steering at a wavelength of 1550 nm, and a diffraction efficiency (DE) higher than 72%.

  12. Optical trapping apparatus, methods and applications using photonic crystal resonators

    SciTech Connect

    Erickson, David; Chen, Yih-Fan

    2015-06-16

    A plurality of photonic crystal resonator optical trapping apparatuses and a plurality optical trapping methods using the plurality of photonic crystal resonator optical trapping apparatuses include located and formed over a substrate a photonic waveguide that is coupled (i.e., either separately coupled or integrally coupled) with a photonic crystal resonator. In a particular embodiment, the photonic waveguide and the photonic crystal resonator comprise a monocrystalline silicon (or other) photonic material absent any chemical functionalization. In another particular embodiment, the photonic waveguide and the photonic crystal resonator comprise a silicon nitride material which when actuating the photonic crystal resonator optical trapping apparatus with a 1064 nanometer resonant photonic radiation wavelength (or other resonant photonic radiation wavelength in a range from about 700 to about 1200 nanometers) provides no appreciable heating of an aqueous sample fluid that is analyzed by the photonic crystal resonator optical trapping apparatus.

  13. Metallic photonic crystals at optical wavelengths

    NASA Astrophysics Data System (ADS)

    El-Kady, I.; Sigalas, M. M.; Biswas, R.; Ho, K. M.; Soukoulis, C. M.

    2000-12-01

    We theoretically study three-dimensional metallic photonic-band-gap (PBG) materials at near-infrared and optical wavelengths. Our main objective is to find the importance of absorption in the metal and the suitability of observing photonic band gaps in this structure. For that reason, we study simple cubic structures and the metallic scatterers are either cubes or interconnected metallic rods. Several different metals have been studied (aluminum, gold, copper, and silver). Copper gives the smallest absorption and aluminum is more absorptive. The isolated metallic cubes are less lossy than the connected rod structures. The calculations suggest that isolated copper scatterers are very attractive candidates for the fabrication of photonic crystals at the optical wavelengths.

  14. Optical nanofiber-based photonic crystal cavity.

    PubMed

    Nayak, K P; Zhang, Pengfei; Hakuta, K

    2014-01-15

    We demonstrate the fabrication of photonic crystal (PhC) cavities on optical nanofibers using femtosecond laser ablation. PhC cavities with cavity lengths varying from 0.54 to 3.43 mm are fabricated by controlling the profile of the nanocrater array formed on the nanofiber. Such PhC cavities show high transmission of 87% for a finesse of 39. For higher finesse values from 150 to 500, the transmission can still be maintained at 20%-25%. Due to the strong confinement of the field and the efficient coupling to single-mode optical fibers, such nanofiber-based PhC cavities may become an interface between quantum and classical networks. PMID:24562114

  15. Detection of six genetically modified maize lines using optical thin-film biosensor chips.

    PubMed

    Bai, Sulan; Zhang, Jie; Li, Shucheng; Chen, Haodong; Terzaghi, William; Zhang, Xin; Chi, Xiurong; Tian, Jin; Luo, Hongxia; Huang, Wensheng; Chen, Ying; Zhang, Yaochuan

    2010-08-11

    As more and more genetically modified organisms (GMO) are commercialized, efficient and inexpensive assays are required for their quick detection. An event-specific detection strategy based on the unique and specific sequences of integration junctions is useful because of its high specificity. This study developed a system for detecting six GM maize lines (Bt11, Bt176, GA21, MON810, NK603, and T25) using optical silicon thin-film biosensor chips. Aldehyde-labeled probes were arrayed and covalently attached to a hydrazine-derivatized chip surface. Biotinylated PCR amplicons were then hybridized with the probes. After washing and brief incubation with an anti-biotin IgG horseradish peroxidase conjugate and a precipitable horseradish peroxidase substrate, biotinylated PCR amplicons perfectly matched with the probes can be visualized by the color change on the chip surface (gold to blue/purple). This assay is extremely robust, exhibits high sensitivity and specificity, and is flexible from low through moderate to high throughput. PMID:20614904

  16. Highly sensitive optical fibre long period grating biosensor anchored with silica core gold shell nanoparticles.

    PubMed

    Marques, L; Hernandez, F U; James, S W; Morgan, S P; Clark, M; Tatam, R P; Korposh, S

    2016-01-15

    An optical fibre long period grating (LPG), modified with a coating of silica core gold shell (SiO2:Au) nanoparticles (NPs) deposited using the layer-by-layer method, was employed for the development of a biosensor. The SiO2:Au NPs were electrostatically assembled onto the LPG with the aid of a poly(allylamine hydrochloride) (PAH) polycation layer. The LPG sensor operates at the phase matching turning point to provide the highest sensitivity. The SiO2:Au NPs were modified with biotin, which was used as a ligand for streptavidin (SV) detection. The sensing mechanism is based on the measurement of the refractive index change induced by the binding of the SV to the biotin. The effect on sensitivity of increasing the surface area by virtue of the SiO2:Au nanoparticles' diameter and film thickness was studied. The lowest measured concentration of SV was 2.5nM, achieved using an LPG modified with a 3 layer (PAH/SiO2:Au) thin film composed of SiO2 NPs of 300nm diameter with a binding constant of k=1.7(pM)(-1), sensitivity of 6.9nm/ng/mm(2) and limit of detection of 19pg/mm(2). PMID:26319165

  17. Combining an Optical Resonance Biosensor with Enzyme Activity Kinetics to Understand Protein Adsorption and Denaturation

    PubMed Central

    Wilson, Kerry A.; Finch, Craig A.; Anderson, Phillip; Vollmer, Frank; Hickman, James J.

    2014-01-01

    Understanding protein adsorption and resultant conformation changes on modified and unmodified silicon dioxide surfaces is a subject of keen interest in biosensors, microfluidic systems and for medical diagnostics. However, it has been proven difficult to investigate the kinetics of the adsorption process on these surfaces as well as understand the topic of the denaturation of proteins and its effect on enzyme activity. A highly sensitive optical whispering gallery mode (WGM) resonator was used to study a catalytic enzyme’s adsorption processes on different silane modified glass substrates (plain glass control, DETA, 13F, and SiPEG). The WGM sensor was able to obtain high resolution kinetic data of glucose oxidase (GO) adsorption with sensitivity of adsorption better than that possible with SPR. The kinetic data, in combination with a functional assay of the enzyme activity, was used to test hypotheses on adsorption mechanisms. By fitting numerical models to the WGM sensograms for protein adsorption, and by confirming numerical predictions of enzyme activity in a separate assay, we were able to identify mechanisms for GO adsorption on different alkylsilanes and infer information about the adsorption of protein on nanostructured surfaces. PMID:25453976

  18. Optical biosensor system for the quick and reliable detection of virus infections: VIROSENS

    NASA Astrophysics Data System (ADS)

    Proll, Günther; Hartjes, Anja; Sinclair, Alexander; Markovic, Goran; Pröll, Florian; Patel, Pranav; Niedrig, Matthias

    2014-10-01

    Viral infections are of special threat because they can induce severe courses of disease but only few medical treatments are available. Because of socio-economic and climate changes, increased worldwide mobility and population growth, the risk of newly occurring and quickly spreading viral pathogens has increased. A diagnosis of these diseases at an early stage is essential for a quick risk assessment and a proper health management as well as patient's treatment in an optimal way. Currently, the diagnosis of such diseases is based on time consuming and costly detection methods that can only be performed by specially trained personnel in laboratories at specific security levels. Aim of the project VIROSENS is the development of a biosensor platform that can specifically detect virus particles as well as virus-specific antibodies out of biological matrices like blood, serum, plasma and other body fluids. For this purpose, a disposable cartridge for such antibody- and virus-arrays is designed and developed within the project. The optical detection of viruses is performed with a portable device that will be benchmarked and evaluated concerning currently used standard detection methods in terms of its analytical performance. Within this project, a novel combination of serological tests and direct detection of virus particles will be developed, which will provide faster and more reliable results than presently available and used test systems.

  19. Label-Enhanced Surface Plasmon Resonance: A New Concept for Improved Performance in Optical Biosensor Analysis

    PubMed Central

    Granqvist, Niko; Hanning, Anders; Eng, Lars; Tuppurainen, Jussi; Viitala, Tapani

    2013-01-01

    Surface plasmon resonance (SPR) is a well-established optical biosensor technology with many proven applications in the study of molecular interactions as well as in surface and material science. SPR is usually applied in the label-free mode which may be advantageous in cases where the presence of a label may potentially interfere with the studied interactions per se. However, the fundamental challenges of label-free SPR in terms of limited sensitivity and specificity are well known. Here we present a new concept called label-enhanced SPR, which is based on utilizing strongly absorbing dye molecules in combination with the evaluation of the full shape of the SPR curve, whereby the sensitivity as well as the specificity of SPR is significantly improved. The performance of the new label-enhanced SPR method was demonstrated by two simple model assays: a small molecule assay and a DNA hybridization assay. The small molecule assay was used to demonstrate the sensitivity enhancement of the method, and how competitive assays can be used for relative affinity determination. The DNA assay was used to demonstrate the selectivity of the assay, and the capabilities in eliminating noise from bulk liquid composition variations. PMID:24217357

  20. Silicon Photonic Crystal Nanocavity-Coupled Waveguides for Error-Corrected Optical Biosensing

    PubMed Central

    Pal, Sudeshna; Guillermain, Elisa; Sriram, Rashmi; Miller, Benjamin L.; Fauchet, Philippe M.

    2011-01-01

    A photonic crystal (PhC) waveguide based optical biosensor capable of label-free and error-corrected sensing was investigated in this study. The detection principle of the biosensor involved shifts in the resonant mode wavelength of nanocavities coupled to the silicon PhC waveguide due to changes in ambient refractive index. The optical characteristics of the nanocavity structure were predicted by FDTD theoretical methods. The device was fabricated using standard nanolithography and reactive-ion-etching techniques. Experimental results showed that the structure had a refractive index sensitivity of 10−2 RIU. The biosensing capability of the nanocavity sensor was tested by detecting human IgG molecules. The device sensitivity was found to be 2.3 ± 0.24 × 105 nm/M with an achievable lowest detection limit of 1.5 fg for human IgG molecules. Additionally, experimental results demonstrated that the PhC devices were specific in IgG detection and provided concentration-dependent responses consistent with Langmuir behavior. The PhC devices manifest outstanding potential as microscale label-free error-correcting sensors, and may have future utility as ultrasensitive multiplex devices. PMID:21524903

  1. Optical biosensor for environmental on-line monitoring of naphthalene and salicylate bioavailability with an immobilized bioluminescent catabolic reporter bacterium

    SciTech Connect

    Heitzer, A.; Malachowsky, K.; Thonnard, J.E.

    1994-05-01

    An optical whole-cell biosensor based on a genetically engineered bioluminescent catabolic reporter bacterium was developed for continuous on-line monitoring of naphthalene and salicylate bioavailability and microbial catabolic activity potential in waste streams. The bioluminescent reporter bacterium, Pseudomonas fluorescens HK44, carries a transcriptional nahG-luxCDABE fusion for naphthalene and salicylate catabolism. Exposure to either compound resulted in inducible bioluminescence. The reporter culture was immobilized onto the surface of an optical guide by using strontium alginate. The biosensor probe was then inserted into a measurement cell which simultaneously received the waste stream solution and a maintenance medium. Exposure under defined conditions to both naphthalene and salicylate resulted in a rapid increase in bioluminescence. The magnitude of the response and the response time were concentration dependent. Good reproducibility of the response was observed during repetitive perturbations with either napthalene or salicylate. Exposure to other compounds, such as glucose and complex nutrient medium or toluene, resulted in either minor bioluminescence increases after significantly longer response times compared with naphthalene or no response, respectively. The environmental utility of the biosensor was tested by using real pollutant mixtures. A specific bioluminescence response was obtained after exposure to either an aqueous solution saturated with JP-4 fuel or an aqueous leachate from a manufactured-gas plant soil, since napthalene was present in both pollutant mixtures. 43 refs., 4 figs., 1 tab.

  2. Methods of making composite optical devices employing polymer liquid crystal

    DOEpatents

    Jacobs, S.D.; Marshall, K.L.; Cerqua, K.A.

    1991-10-08

    Composite optical devices are disclosed using polymer liquid crystal materials both as optical and adhesive elements. The devices are made by assembling a heated polymer liquid crystal compound, while in a low viscosity form between optically transparent substrates. The molecules of the polymer are oriented, while in the liquid crystalline state and while above the glass transition temperature (T[sub g]) of the polymer, to provide the desired optical effects, such as polarization, and selective reflection. The liquid crystal polymer cements the substrates together to form an assembly providing the composite optical device. 7 figures.

  3. Methods of making composite optical devices employing polymer liquid crystal

    DOEpatents

    Jacobs, Stephen D.; Marshall, Kenneth L.; Cerqua, Kathleen A.

    1991-01-01

    Composite optical devices using polymer liquid crystal materials both as optical and adhesive elements. The devices are made by assembling a heated polymer liquid crystal compound, while in a low viscosity form between optically transparent substrates. The molecules of the polymer are oriented, while in the liquid crystalline state and while above the glass transition temperature (T.sub.g) of the polymer, to provide the desired optical effects, such as polarization, and selective reflection. The liquid crystal polymer cements the substrates together to form an assembly providing the composite optical device.

  4. Optically rewritable 3D liquid crystal displays.

    PubMed

    Sun, J; Srivastava, A K; Zhang, W; Wang, L; Chigrinov, V G; Kwok, H S

    2014-11-01

    Optically rewritable liquid crystal display (ORWLCD) is a concept based on the optically addressed bi-stable display that does not need any power to hold the image after being uploaded. Recently, the demand for the 3D image display has increased enormously. Several attempts have been made to achieve 3D image on the ORWLCD, but all of them involve high complexity for image processing on both hardware and software levels. In this Letter, we disclose a concept for the 3D-ORWLCD by dividing the given image in three parts with different optic axis. A quarter-wave plate is placed on the top of the ORWLCD to modify the emerging light from different domains of the image in different manner. Thereafter, Polaroid glasses can be used to visualize the 3D image. The 3D image can be refreshed, on the 3D-ORWLCD, in one-step with proper ORWLCD printer and image processing, and therefore, with easy image refreshing and good image quality, such displays can be applied for many applications viz. 3D bi-stable display, security elements, etc. PMID:25361316

  5. Electrochemical and optical biosensors based on nanomaterials and nanostructures: a review.

    PubMed

    Li, Ming; Li, Rui; Li, Chang Ming; Wu, Nianqiang

    2011-01-01

    Nanomaterials and nanostructures exhibit unique size-tunable and shape-dependent physicochemical properties that are different from those of bulk materials. Advances of nanomaterials and nanostructures open a new door to develop various novel biosensors. The present work has reviewed the recent progress in electrochemical, surface plasmon resonance (SPR), surface-enhanced Raman scattering (SERS) and fluorescent biosensors based on nanomaterials and nanostructures. An emphasis is put on the research that demonstrates how the performance of biosensors such as the limit of detection, sensitivity and selectivity is improved by the use of nanomaterials and nanostructures. PMID:21622273

  6. Optical pulse generator using liquid crystal light valve

    NASA Technical Reports Server (NTRS)

    Collins, S. A., Jr.

    1984-01-01

    Numerical optical computing is discussed. A design for an optical pulse generator using a Hughes Liquid crystal light valve and intended for application as an optical clock in a numerical optical computer is considered. The pulse generator is similar in concept to the familiar electronic multivibrator, having a flip-flop and delay units.

  7. Development of a Mass Sensitive Quartz Crystal Microbalance (QCM)-Based DNA Biosensor Using a 50 MHz Electronic Oscillator Circuit

    PubMed Central

    García-Martinez, Gonzalo; Bustabad, Enrique Alonso; Perrot, Hubert; Gabrielli, Claude; Bucur, Bogdan; Lazerges, Mathieu; Rose, Daniel; Rodriguez-Pardo, Loreto; Fariña, Jose; Compère, Chantal; Vives, Antonio Arnau

    2011-01-01

    This work deals with the design of a high sensitivity DNA sequence detector using a 50 MHz quartz crystal microbalance (QCM) electronic oscillator circuit. The oscillator circuitry is based on Miller topology, which is able to work in damping media. Calibration and experimental study of frequency noise are carried out, finding that the designed sensor has a resolution of 7.1 ng/cm2 in dynamic conditions (with circulation of liquid). Then the oscillator is proved as DNA biosensor. Results show that the system is able to detect the presence of complementary target DNAs in a solution with high selectivity and sensitivity. DNA target concentrations higher of 50 ng/mL can be detected. PMID:22164037

  8. A biosensor of high-density lipoprotein of human serum on a liquid crystal and polymer composite film

    NASA Astrophysics Data System (ADS)

    Lin, Yi-Hsin; Chang, Kai-Han; Chu, Wei-Lin; Tsou, Yu-Shih; Wu, Li-Ching; Li, Chien-Feng

    2013-10-01

    A biosensor for the concentration of high-density lipoprotein (HDL) in human serum on a liquid crystal and polymer composite film (LCPCF) is demonstrated. The sensing mechanism is based on a polar-polar interaction between orientation of LC directors and HDL in human serum. The concentration of polar HDL in human serum affects the orientations of LC directors at the interface between LCPCF and the human serum. In addition, the surface free energy of LCPCF changes with the applied voltage due to the electrically tunable orientations of LC directors anchored among the polymer grains of LCPCF. As a result, the droplet motion of human serum on LCPCF under applied voltages can sense the concentration of HDL in human serum.

  9. Development of a mass sensitive quartz crystal microbalance (QCM)-based DNA biosensor using a 50 MHz electronic oscillator circuit.

    PubMed

    García-Martinez, Gonzalo; Bustabad, Enrique Alonso; Perrot, Hubert; Gabrielli, Claude; Bucur, Bogdan; Lazerges, Mathieu; Rose, Daniel; Rodriguez-Pardo, Loreto; Fariña, Jose; Compère, Chantal; Vives, Antonio Arnau

    2011-01-01

    This work deals with the design of a high sensitivity DNA sequence detector using a 50 MHz quartz crystal microbalance (QCM) electronic oscillator circuit. The oscillator circuitry is based on Miller topology, which is able to work in damping media. Calibration and experimental study of frequency noise are carried out, finding that the designed sensor has a resolution of 7.1 ng/cm(2) in dynamic conditions (with circulation of liquid). Then the oscillator is proved as DNA biosensor. Results show that the system is able to detect the presence of complementary target DNAs in a solution with high selectivity and sensitivity. DNA target concentrations higher of 50 ng/mL can be detected. PMID:22164037

  10. Optical, dielectric and microhardness studies on (100) directed ADP crystal.

    PubMed

    Rajesh, P; Ramasamy, P

    2009-09-15

    (100) directed ammonium dihydrogen phosphate single crystal has been grown using the uniaxially solution-crystallization method of Sankaranarayanan-Ramasamy (SR). The size of the grown crystal is 40 mm in diameter and 50mm in thickness. The grown crystals were characterized by UV-vis spectroscopy, Vickers hardness and dielectric studies. Comparing the (100) plane of the conventional method grown ADP crystal with (100) directed SR method grown ADP crystal, optical transparency, dielectric constant and Vickers hardness number are increased and dielectric loss is decreased in SR method grown crystal. PMID:19592298

  11. A comparative study of the cytoskeleton binding drugs nocodazole and taxol with a mammalian cell quartz crystal microbalance biosensor: different dynamic responses and energy dissipation effects.

    PubMed

    Marx, Kenneth A; Zhou, Tiean; Montrone, Anne; McIntosh, Donna; Braunhut, Susan J

    2007-02-01

    The quartz crystal microbalance (QCM) was used to create piezoelectric whole-cell biosensors utilizing either living endothelial cells (ECs) or the metastatic human mammary cancer cell line MDA-MB-231 adhering to the gold QCM surface under in vitro growth conditions. We utilized the whole-cell QCM biosensors for the detection of the effects of varying concentrations of the microtubule binding drugs taxol and nocodazole by measuring changes in the QCM steady state frequency (Deltaf) and motional resistance (DeltaR), shift values. Using 0.11-50 microM nocodazole, we observed the Deltaf shift values of the biosensors, consisting of 20,000 ECs, to decrease significantly in magnitude (nearly 100%) to a limiting value, in a dose-dependent fashion, over a 5- to 6-h incubation period following drug addition. This effect is consistent with nocodazole's known disruption of intracellular microtubules. On the other hand, 10 microM taxol caused little alteration in Deltaf over the same time period, consistent with its microtubule hyperstabilization effect. When the EC QCM biosensor Deltaf shift values were normalized by the number of ECs found firmly attached to the QCM surface via trypsin removal and electronic counting, the dose curve was shifted to lower nocodazole concentrations, resulting in a more sensitive drug biosensor. The kinetics of the Deltaf decrease with increasing nocodazole concentrations measured by the EC QCM biosensor was found to be similar at all drug concentrations and was well fit by a single first-order exponential decay equation. For all nocodazole doses, t(0.5) was invariant, averaging t(0.5)=0.83+/-0.14 h. These data demonstrate that a single dynamic sensing system within the cell, the microtubules, is disrupted by the addition of nocodazole and this process is sensed by the cell QCM biosensor. This interpretation of the data was confirmed by a fluorescence light microscopy investigation of ECs undergoing treatment with increasing nocodazole doses

  12. Planar optics with patterned chiral liquid crystals

    NASA Astrophysics Data System (ADS)

    Kobashi, Junji; Yoshida, Hiroyuki; Ozaki, Masanori

    2016-06-01

    Reflective metasurfaces based on metallic and dielectric nanoscatterers have attracted interest owing to their ability to control the phase of light. However, because such nanoscatterers require subwavelength features, the fabrication of elements that operate in the visible range is challenging. Here, we show that chiral liquid crystals with a self-organized helical structure enable metasurface-like, non-specular reflection in the visible region. The phase of light that is Bragg-reflected off the helical structure can be controlled over 0–2π depending on the spatial phase of the helical structure; thus planar elements with arbitrary reflected wavefronts can be created via orientation control. The circular polarization selectivity and external field tunability of Bragg reflection open a wide variety of potential applications for this family of functional devices, from optical isolators to wearable displays.

  13. Liquid-crystal prisms for tip-tilt adaptive optics.

    PubMed

    Love, G D; Major, J V; Purvis, A

    1994-08-01

    Results from an electrically addressed liquid-crystal cell producing continuous phase profiles are presented. The adaptive deflection of a beam of light for use in a tip-tilt adaptive optics system is demonstrated. We compare the optical performance of liquid-crystal prisms with experimental data on atmospheric seeing at the William Herschel Telescope. PMID:19844566

  14. Determining crystal growth kinetic parameters using optical fibre sensors

    NASA Astrophysics Data System (ADS)

    Boerkamp, M.; Lamb, D. W.; Lye, P. G.

    2012-12-01

    The capability of an 'intrinsic exposed core optical fibre sensor' (IECOFS) as a monitoring device of scale formation has been evaluated. The IECOFS has been used to measure kinetics parameters of calcium carbonate heterogeneous crystal growth such as the activation energy, the crystal growth rate and the induction time. The IECOFS was able to evaluate crystal growth inhibition through the use of chemical inhibitors.

  15. Microalgae fiber optic biosensors for herbicide monitoring using sol-gel technology.

    PubMed

    Peña-Vázquez, Elena; Maneiro, Emilia; Pérez-Conde, Concepción; Moreno-Bondi, Maria Cruz; Costas, Eduardo

    2009-08-15

    Three microalgal species (Dictyosphaerium chlorelloides (D.c.), Scenedesmus intermedius (S.i.) and Scenedesmus sp. (S.s.)) were encapsulated in silicate sol-gel matrices and the increase in the amount of chlorophyll fluorescence signal was used to quantify simazine. Influence of several parameters on the preparation of the sensing layers has been evaluated: effect of pH on sol-gel gelation time; effect of algae density on sensor response; influence of glycerol (%) on the membrane stability. Long term stability was also tested and the fluorescence signal from biosensors remained stable for at least 3 weeks. D.c. biosensor presented the lowest detection limits for simazine (3.6 microg L(-1)) and the broadest dynamic calibration range (19-860 microg L(-1)) with IC(50) 125+/-14 microg L(-1). Biosensor was validated by HPLC with UV/DAD detection. The biosensor showed response to those herbicides that inhibit the photosynthesis at photosystem II (triazines: simazine, atrazine, propazine, terbuthylazine; urea based herbicides: linuron). However, no significant increases of fluorescence response was obtained for similar concentrations of 2,4-D (hormonal herbicide) or Cu(II). The combined use of two biosensors that use two different genotypes, sensitive and resistant to simazine, jointly allowed improving microalgae biosensor specificity. PMID:19497732

  16. Utilizing a high fundamental frequency quartz crystal resonator as a biosensor in a digital microfluidic platform.

    PubMed

    Lederer, Thomas; Stehrer, Brigitte P; Bauer, Siegfried; Jakoby, Bernhard; Hilber, Wolfgang

    2011-12-01

    We demonstrate the operation of a digital microfluidic lab-on-a-chip system utilizing Electro Wetting on Dielectrics (EWOD) as the actuation principle and a High Fundamental Frequency (HFF; 50 MHz) quartz crystal microbalance (QCM) resonator as a mass-sensitive sensor. In a first experiment we have tested the reversible formation of a phosphor-lipid monolayer of phospholipid vesicles out of an aqueous buffer suspension onto a bio-functionalized integrated QCM sensor. A binding of bio-molecules results in an altered mass load of the resonant sensor and a shift of the resonance frequency can be measured. In the second part of the experiment, the formation of a protein multilayer composed of the biomolecule streptavidin and biotinylated immunoglobulin G was monitored. Additionally, the macroscopic contact angle was optically measured in order to verify the bio-specific binding and to test the implications onto the balance of the surface tensions. Using these sample applications, we were able to demonstrate and to verify the feasibility of integrating a mass-sensitive QCM sensor into a digital microfluidic chip. PMID:22241942

  17. Optical dephasing in semiconductor mixed crystals

    NASA Astrophysics Data System (ADS)

    Siegner, U.; Weber, D.; Göbel, E. O.; Bennhardt, D.; Heuckeroth, V.; Saleh, R.; Baranovskii, S. D.; Thomas, P.; Schwab, H.; Klingshirn, C.; Hvam, J. M.; Lyssenko, V. G.

    1992-08-01

    The influence of disorder and localization on optical dephasing of excitons in the semiconductor mixed crystals CdS1-xSex and AlxGa1-xAs has been investigated by means of time-resolved four-wave mixing and photon echo experiments. A dephasing time of several hundreds of picoseconds is found for resonantly excited localized excitons in CdS1-xSex while the dephasing time in AlxGa1-xAs amounts to only a few picoseconds. In CdS1-xSex dephasing results mainly from hopping processes, i.e., exciton-phonon interaction. The contribution of disorder is negligible in terms of phase relaxation in CdS1-xSex. In contrast, in AlxGa1-xAs elastic disorder scattering yields an essential contribution to the dephasing rate. We present a theoretical model, which treats dephasing of optical excitations in a disordered semiconductor, including the influence of disorder as well as exciton-phonon interaction. On the base of this model, the experimentally observed differences in the dephasing behavior of excitons in CdS1-xSex and AlxGa1-xAs are related to the microscopic structure of the disorder potential and the mechanism of exciton localization.

  18. An ultrasensitive optical label-free polymeric biosensor based on concentric triple microring resonators with a central microdisk resonator

    NASA Astrophysics Data System (ADS)

    Malmir, Kiana; Habibiyan, Hamidreza; Ghafoorifard, Hassan

    2016-04-01

    In this paper we propose an optical label-free biosensor based on a polymeric platform. Label-free biosensors have not the drawbacks and stability problems of commercialized devices which are used for detection of labeled molecules. In addition, we choose polymeric platform, due to simple and low cost fabrication process and also high biocompatibility properties. The suggested structure consists of concentric triple ring resonators along with a disk resonator which offers deeper notches, higher sensitivity and vaster detection area with respect to other similar configurations such as single ring resonator, double concentric ring resonators, etc. Our numerical simulations based on the finite difference time domain (FDTD) method, show that in optimized structure, a transmission notch depth of -48.7 dB for sensor at rest and a free spectral range of 56 nm are achievable. In addition, resonance wavelength sensitivity and output power sensitivity of sensor are 1000 nm/RIU and 1.8×104 dB/RIU, respectively. The external radius of outer ring resonator is only 5 μm, and detection area of the sensor is 40.37 μm2. With this small size, to the best of our knowledge, the obtained notch depth and sensitivity parameters are one of the highest values in ring resonator-based biosensors reported to date.

  19. QUARTZ CRYSTAL MICROBALANCE BIOSENSOR FOR MEASUREMENT OF 2,4-D IN WATER

    EPA Science Inventory

    Due to proportional relationship between vibrational frequency and surface mass, the quartz crystal microbalance (QCM) has been used to detect the accumulation of small quantities of chemical and biological compounds on electrode-covered quartz crystals. lassically, these devices...

  20. Optical characterization of lyotropic chromonic liquid crystals

    NASA Astrophysics Data System (ADS)

    Liu, Hui

    Lyotropic chromonic liquid crystals (LCLCs) represent a special class of lyotropic mesophases markedly different from conventional amphiphilic mesogens. Materials forming LCLCs are composed of plank-like molecules with a polyaromatic central core and hydrophilic ionic groups at the periphery. The individual molecules tend to assemble into rodlike aggregates that form the N phase once the concentration exceeds about 0.1M. The LCLC materials show a tremendous potential for applications in optics as self-assembling polarizing and compensating films and in the area of real-time biological sensing. The emerging applications require an understanding of basic properties of LCLC. This work addresses these needs by providing the optical characterization of LCLC. We studied in detail the optical anisotropic properties of three different nematic LCLCs: disodium cromoglycate (DSCG), Blue 27, and Violet 20. We determined the birefringence of these three materials as the function of the temperature T and wavelength lambda and the corresponding dependencies of the absorption coefficients for Blue 27 and Violet 20. The birefringence is negative and significantly lower in the absolute value as compared to the birefringence of typical thermotropic N materials. We determined the scalar order parameter of the nematic phase of Blue 27 and its temperature dependence. The scalar order parameter is close to the one predicted by the classic Onsager theory for solutions of rigid rods. However, this similarity is not complete, as the measured scalar order parameter depends on temperature. The I-N pretransitional fluctuations in an aqueous solution of DSCG were studied by light scattering. We obtained the correlation length of the orientational order-parameter fluctuations of isotropic DSCG solution. The pretransitional behavior of light scattering does not completely follow the classic Landau-de Gennes model. This feature is explained by the variable length of DSCG aggregates as a function

  1. Computational studies of optical textures of twist disclination loops in liquid-crystal films by using the finite-difference time-domain method

    NASA Astrophysics Data System (ADS)

    Hwang, Dae Kun; Rey, Alejandro D.

    2006-02-01

    Optical images of textured liquid-crystal films containing various types of twist disclination loops are computed using an approximate matrix method and a direct numerical simulation based on the finite-difference time-domain (FDTD) method. The selected defects introduce large multidirectional spatial gradients in the optic axis, mimicking the orientation textures that arise in the construction and use of biosensors based on liquid-crystal vision. It is shown that under these experimentally relevant conditions, the matrix method fails to capture important signatures in the transmitted light intensity under crossed polarizers. The differences between the predictions by the two methods are analyzed with respect to gradients in the optic axis. We show that the FDTD method is a useful tool to perform computational optics of textured liquid-crystal films.

  2. Use of a photonic crystal for optical amplifier gain control

    DOEpatents

    Lin, Shawn-Yu; Fleming, James G.; El-Kady, Ihab

    2006-07-18

    An optical amplifier having a uniform gain profile uses a photonic crystal to tune the density-of-states of a gain medium so as to modify the light emission rate between atomic states. The density-of-states of the gain medium is tuned by selecting the size, shape, dielectric constant, and spacing of a plurality of microcavity defects in the photonic crystal. The optical amplifier is particularly useful for the regeneration of DWDM signals in long optical fibers.

  3. Lightweight optical mirrors formed in single crystal substrate

    NASA Technical Reports Server (NTRS)

    Bly, Vincent T. (Inventor)

    2006-01-01

    This invention is directed to a process for manufacturing a lightweight mirror from a single crystal material, such as single crystal silicon. As a near perfect single crystal material, single crystal silicon has much lower internal stress than a conventional material. This means much less distortion of the optical surface during the light weighting process. After being ground and polished, a single crystal silicon mirror is light weighted by removing material from the back side using ultrasonic machining. After the light weighting process, the single crystal silicon mirror may be used as-is or further figured by conventional polishing or ion milling, depending on the application and the operating wavelength.

  4. Minimizing radiation damage in nonlinear optical crystals

    DOEpatents

    Cooke, D.W.; Bennett, B.L.; Cockroft, N.J.

    1998-09-08

    Methods are disclosed for minimizing laser induced damage to nonlinear crystals, such as KTP crystals, involving various means for electrically grounding the crystals in order to diffuse electrical discharges within the crystals caused by the incident laser beam. In certain embodiments, electrically conductive material is deposited onto or into surfaces of the nonlinear crystals and the electrically conductive surfaces are connected to an electrical ground. To minimize electrical discharges on crystal surfaces that are not covered by the grounded electrically conductive material, a vacuum may be created around the nonlinear crystal. 5 figs.

  5. Minimizing radiation damage in nonlinear optical crystals

    DOEpatents

    Cooke, D. Wayne; Bennett, Bryan L.; Cockroft, Nigel J.

    1998-01-01

    Methods are disclosed for minimizing laser induced damage to nonlinear crystals, such as KTP crystals, involving various means for electrically grounding the crystals in order to diffuse electrical discharges within the crystals caused by the incident laser beam. In certain embodiments, electrically conductive material is deposited onto or into surfaces of the nonlinear crystals and the electrically conductive surfaces are connected to an electrical ground. To minimize electrical discharges on crystal surfaces that are not covered by the grounded electrically conductive material, a vacuum may be created around the nonlinear crystal.

  6. Development of a fast and sensitive glucose biosensor using iridium complex-doped electrospun optical fibrous membrane.

    PubMed

    Zhou, Cuisong; Shi, Yalin; Ding, Xiaodong; Li, Ming; Luo, Jiaojiao; Lu, Zhiyun; Xiao, Dan

    2013-01-15

    Polystyrene electrospun optical fibrous membrane (EOF) was fabricated using a one-step electrospinning technique, functionalized with glucose oxidases (GOD/EOF), and used as a quick and highly sensitive optical biosensor. Because of the doped iridium complex, the fibrous membrane emitted yellow luminescence (562 nm) when excited at 405 nm. Its luminescence was significantly enhanced with the presence of extremely low concentration glucose. The detection limit was of 1.0 × 10(-10) M (S/N = 3), superior to that of reported glucose biosensor with 1.2 × 10(-10) M. A linear range between the relative intensity increase and the logarithm of glucose concentration was exhibited from 3.0 × 10(-10) M to 1.3 × 10(-4) M, which was much wider than reported results. Notably, the response time was less than 1 s. These high sensitivity and fast response were attributed to the high surface-area-to-volume of the porous fibrous membrane, the efficient GOD biocatalyst reaction on the fibers surface, as well as the fast electron or energy transfer between dissolved oxygen and the optical fibrous membrane. PMID:23215003

  7. Study on micro-crystallization, growth, optical properties and defects of a nonlinear optical crystal: MnHg(SCN) 4

    NASA Astrophysics Data System (ADS)

    Liu, Xitao; Wang, Xinqiang; Sun, Zhihua; Lin, Xiaojing; Zhang, Guanghui; Xu, Dong

    2011-02-01

    High optical quality single crystals of a nonlinear optical material, manganese mercury thiocyanate, MnHg(SCN) 4 (MMTC), with dimensions up to 21×14×13 mm 3 have been grown by the solvent evaporation method. The growth habit of MMTC crystal crystallized under different conditions was investigated by means of micro-crystallization method. Two typical growth morphologies of the crystal were indexed and compared with the morphology deduced from the single crystal structure data. The results show that two novel {1 0 0} and {1 1 2} facets appear during the crystal growth. Powder second harmonic generation and spectral transmittance measurements were also performed. The results indicate that MMTC is phase-matchable and the UV transparency cutoff occurs at 373 nm. Various defects were found in MMTC crystal. Their formation mechanisms and the methods to eliminate these defects are discussed.

  8. Disposable micro-fluidic biosensor array for online parallelized cell adhesion kinetics analysis on quartz crystal resonators

    NASA Astrophysics Data System (ADS)

    Cama, G.; Jacobs, T.; Dimaki, M. I.; Svendsen, W. E.; Hauptmann, P.; Naumann, M.

    2010-08-01

    In this contribution we present a new disposable micro-fluidic biosensor array for the online analysis of adherent Madin Darby canine kidney (MDCK-II) cells on quartz crystal resonators (QCRs). The device was conceived for the parallel cultivation of cells providing the same experimental conditions among all the sensors of the array. As well, dedicated sensor interface electronics were developed and optimized for fast spectra acquisition of all 16 QCRs with a miniaturized impedance analyzer. This allowed performing cell cultivation experiments for the observation of fast cellular reaction kinetics with focus on the comparison of the resulting sensor signals influenced by different cell distributions on the sensor surface. To prove the assumption of equal flow circulation within the symmetric micro-channel network and support the hypothesis of identical cultivation conditions for the cells living above the sensors, the influence of fabrication tolerances on the flow regime has been simulated. As well, the shear stress on the adherent cell layer due to the flowing media was characterized. Injection molding technology was chosen for the cheap mass production of disposable devices. Furthermore, the injection molding process was simulated in order to optimize the mold geometry and minimize the shrinkage and the warpage of the parts. MDCK-II cells were cultivated in the biosensor array. Parallel cultivation of cells on the gold surface of the QCRs led to first observations of the impact of the cell distribution on the sensor signals during cell cultivation. Indeed, the initial cell distribution revealed a significant influence on the changes in the measured acoustic load on the QCRs suggesting dissimilar cell migrations as well as proliferation kinetics of a non-confluent MDCK-II cell layer.

  9. Theoretical studies for novel non-linear optical crystals

    NASA Astrophysics Data System (ADS)

    Wu, Kechen; Chen, Chuangtian

    1996-09-01

    To fulfil the "molecular engineering" of non-linear optical crystals, two theoretical models suitable respectively for the studies of the absorption edge and birefringence of a non-linear optical crystal have been set up. Molecular quantum chemical methods have been adopted in the systematic calculations of some typical crystals. DV-SCM-X α methods have been used to calculate the absorption edge on the UV side of BBO, LBO, KB5, KDP, Na 2SbF 5, Ba 2TiSi 2O 8, iodate and NaNO 2 crystals. Ab initio methods have been adopted to study the birefringence of NaNO 2, BBO, LiIO 3 and urea crystals. All the theoretical results agreed well with the experimental values. The relationship between structure and properties has been discussed. The results will be helpful to the search for novel non-linear optical crystals.

  10. Gelled colloidal crystals as tunable optical filters for spectrophotometers

    NASA Astrophysics Data System (ADS)

    Sugao, Yukihiro; Onda, Sachiko; Toyotama, Akiko; Takiguchi, Yoshihiro; Sawada, Tsutomu; Hara, Shigeo; Nishikawa, Suguru; Yamanaka, Junpei

    2016-08-01

    We examined the performance of charged colloidal crystals immobilized in a polymer gel as tunable optical filters. The colloidal crystals of charged silica particles (particle diameter = 121 nm; particle concentration = 3.5 vol %; and Bragg wavelength λB = 630–720 nm) were produced by unidirectional crystallization under a temperature gradient. Photocurable gelation reagents were dissolved in the sample beforehand; this enabled gel immobilization of the crystals under ultraviolet illumination. The crystals had dimensions of more than 25 mm2 in area and 1 mm in thickness, and spatial λB variations of less than 1%. Upon mechanical compression, λB values shifted linearly and reversibly over almost the entire visible spectrum. Using the gelled crystals as tunable optical filters, we measured the transmittance spectra of various samples and found them to be in close agreement with those determined using a spectrophotometer equipped with optical gratings.

  11. Absorption-edge calculations of inorganic nonlinear optical crystals

    NASA Astrophysics Data System (ADS)

    Wu, Kechen; Chen, Chuangtian

    1992-03-01

    A theoretical model suitable for calculating absorption edges of inorganic nonlinear optical (NLO) crystals is introduced. This model is proved to be useful to elucidate the relationship between electronic structures of NLO-active groups and macroscopic properties of absorption edges on the UV side of most of the inorganic nonlinear optical crystals. A systematic calculation of absorption edges on the UV side for several important inorganic NLO crystals is carried out by means of DV-SCM-Xα method and all calculated results are in good agreement with experimental data. These inorganic NLO crystals include LiB3O5(LBO), β-BaB2O4(BBO), KB5, KDP, Na2SbF5, Ba2TiSi2O8, iodate and NaNO2. The calculated energy level structures of LiB3O5 and β-BaB2O4 crystals are compared with the measured XPS spectra. The unusual transparent spectra of KB5 and KDP crystals are partly explained from the microstructure point of view. The effect of lone electron pair in iodate and NaNO2 crystals on their absorption edges are discussed. All these results show that Anionic Group Theory of Nonlinear Optical Crystals is useful to evaluate the absorption edges of the inorganic nonlinear optical crystal and is a powerful tool in a Molecular Engineering approach to search for new nonlinear optical materials.

  12. Progress in linear optics, non-linear optics and surface alignment of liquid crystals

    SciTech Connect

    Ong, H.L.; Meyer, R.B.; Hurd, A.J.; Karn, A.J.; Arakelian, S.M.; Shen, Y.R.; Sanda, P.N.; Dove, D.B.; Jansen, S.A.; Hoffmann, R.

    1989-01-01

    We first discuss the progress in linear optics, in particular, the formulation and application of geometrical-optics approximation and its generalization. We then discuss the progress in non-linear optics, in particular, the enhancement of a first-order Freedericksz transition and intrinsic optical bistability in homeotropic and parallel oriented nematic liquid crystal cells. Finally, we discuss the liquid crystal alignment and surface effects on field-induced Freedericksz transition. 50 refs.

  13. Crystal-free Formation of Non-Oxide Optical Fiber

    NASA Technical Reports Server (NTRS)

    Nabors, Sammy A.

    2015-01-01

    Researchers at NASA Marshall Space Flight Center have devised a method for the creation of crystal-free nonoxide optical fiber preforms. Non-oxide fiber optics are extensively used in infrared transmitting applications such as communication systems, chemical sensors, and laser fiber guides for cutting, welding and medical surgery. However, some of these glasses are very susceptible to crystallization. Even small crystals can lead to light scatter and a high attenuation coefficient, limiting their usefulness. NASA has developed a new method of non-oxide fiber formation that uses axial magnetic fields to suppress crystallization. The resulting non-oxide fibers are crystal free and have lower signal attenuation rates than silica based optical fibers.

  14. REVIEW: Optical neural computers based on photorefractive crystals

    NASA Astrophysics Data System (ADS)

    Bel'dyugin, Igor'M.; Zolotarev, M. V.; Sviridov, K. A.

    1992-05-01

    The results are given of recent investigations of the feasibility of using photorefractive crystals in the construction of optical neural computers and of associative memories. The physical basis of the interaction of laser radiation with photorefractive crystals is given and the principles governing the formation of an all-optical neuron and of links (synapses) between neurons in such crystals are discussed. An analysis is made of the learning capabilities of various models of neural networks (Boltzmann machine, perceptron, associatron, neural networks with competition, etc.) and optical systems implementing these models with the aid of photorefractive crystals are described. Extensive experimental data are reported and the results are given of modeling of various tasks (multidimensional optimization, image recognition, etc.) by optical neural computers.

  15. Spectro-angular optical biosensor based on surface plasmon resonance operating in the visible spectrum

    NASA Astrophysics Data System (ADS)

    Filion Côté, Sandrine; Roche, Philip J. R.; Kirk, Andrew G.

    2013-02-01

    Surface plasmon resonance (SPR) sensing is one of the most widely used methods to implement biosensors due to its sensitivity and capacity for label-free detection. Most conventional SPR sensors measure the change in reflectance at a metal-dielectric interface as a function of either angle or wavelength. However, it has recently been shown that an increase in sensitivity and a greater robustness against noise can be achieved by measuring reflectivity in both domains simultaneously, in a so-called spectro-angular SPR biosensor. This provides a surface plasmon dispersion curve captured on an image sensor that can be tracked in real time. A single value decomposition method is used to project the dispersion curve onto a basis set and allow the image obtained from an unknown refractive index sample to be compared very accurately with a pre-calculated reference set. The objective of the current work is to further improve the detection limit of the spectro-angular biosensor. Simulations have shown that the spatial resolution and numerical precision of the image sensor have a significant impact on the accuracy of the refractive index change measurement. Therefore, upgrading the cameras used for the data acquisition could significantly improve the detection limit of the SPR biosensor. In this work, simulation results are presented to justify the modifications of the experimental system and to estimate the expected improvement in the detection limit of the spectro-angular biosensor by using higher spatial resolution and higher data precision cameras. Experimental results are presented and compared with the previous design.

  16. Label-free optical detection of bacteria on a 1-D photonic crystal of porous silicon

    NASA Astrophysics Data System (ADS)

    Wu, Chia-Chen; Alvarez, Sara D.; Rang, Camilla U.; Chao, Lin; Sailor, Michael J.

    2009-02-01

    The construction of a specific, label-free, bacteria biosensor using porous silicon 1-D photonic crystals will be described. Bacteria resident on the surface of porous silicon act as scattering centers for light resonant with the photonic crystal; the diffusely scattered light possesses the optical spectrum of the underlying photonic crystal. Using a spectrometer fitted to a light microscope, the bacteria are imaged without using exogenous dyes or labels and are quantified by measuring the intensity of scattered light. In order to selectively bind and identify bacteria using porous Si, we use surface modifications to reduce nonspecific binding to the surface and to engineer bacteria specificity onto the surface. Bovine serum albumin (BSA) was adsorbed to the porous Si surface to reduce nonspecific binding of bacteria. The coatings were then chemically activated to immobilize polyclonal antibodies specific to Escherichia coli. Two E. coli strains were used in our study, E. coli DH5α and non-pathogenic enterohemorrhagic Escherichia coli (EHEC) strain. The nonpathogenic Vibrio cholerae O1 strain was used to test for antibody specificity. Successful attachment of antibodies was measured using fluorescence microscopy and the scattering method was used to test for bacteria binding specificity.

  17. Electro-optical switching by liquid-crystal controlled metasurfaces.

    PubMed

    Decker, Manuel; Kremers, Christian; Minovich, Alexander; Staude, Isabelle; Miroshnichenko, Andrey E; Chigrin, Dmitry; Neshev, Dragomir N; Jagadish, Chennupati; Kivshar, Yuri S

    2013-04-01

    We study the optical response of a metamaterial surface created by a lattice of split-ring resonators covered with a nematic liquid crystal and demonstrate millisecond timescale switching between electric and magnetic resonances of the metasurface. This is achieved due to a high sensitivity of liquid-crystal molecular reorientation to the symmetry of the metasurface as well as to the presence of a bias electric field. Our experiments are complemented by numerical simulations of the liquid-crystal reorientation. PMID:23571978

  18. Detection of methicillin-resistant staphylococci by biosensor assay consisting of nanoscale films on optical fiber long-period gratings.

    PubMed

    Bandara, Aloka B; Zuo, Ziwei; Ramachandran, Siddharth; Ritter, Alfred; Heflin, James R; Inzana, Thomas J

    2015-08-15

    Methicillin-resistance among Staphylococcus species is a major health problem in hospitals, communities, and animals. There is a need for culture-free diagnostic assays that can be carried out rapidly, and maintain a high degree of sensitivity and specificity. To address this need an ionic self-assembled multilayer (ISAM) film was deposited on the surface of a long-period grating (LPG) optical fiber by immersion alternately in poly-allylamine hydrochloride and in poly-1-[p-(3'-carboxy-4'-hydroxyphenylazo) benzenesulfonamido]-1,2-ethandiyl (PCBS), resulting in terminal carboxyl groups on the LPG-ISAM. The terminal carboxyl groups were covalently conjugated to monoclonal antibodies (MAb) specific to penicillin-binding-protein 2a of methicillin resistant (MR) staphylococci. After exposure of the LPG-ISAM to 10(2) colony forming units (CFU)/ml of MR S. aureus (MRSA) for 50 min., light transmission was reduced by 19.7%. In contrast, after exposure to 10(6) CFU/ml of methicillin-sensitive S. aureus (MSSA) attenuation of light transmission was less than 1.8%. Exposure of the LPG-ISAM to extracts of liver, lungs, or spleen from mice infected with MRSA attenuated light transmission by 11.7-73.5%. In contrast, exposure of the biosensor to extracts from MSSA-infected mice resulted in 5.6% or less attenuation of light transmission. When the sensor was tested with 36 strains of MR staphylococci, 15 strains of methicillin-sensitive staphylococci, 10 strains of heterologous genera (all at 10(4) CFU/ml), or tissue samples from mice infected with MRSA, there was complete agreement between MR and non-MR bacteria determined by antibiotic susceptibility testing and the biosensor assay when the cutoff value for attenuation of light transmission was 6.3%. Thus, the biosensor described has the potential to detect MR staphylococci in clinical samples with a high degree of sensitivity and specificity. PMID:25845336

  19. Optical and photoelectrochemical study of WTe2 single crystals

    NASA Astrophysics Data System (ADS)

    Desai, P. F.; Patel, D. D.; Bhavsar, D. N.; Jani, A. R.

    2013-06-01

    Single crystals of Tungsten Ditelluride (WTe2) having a layered structure grown by chemical vapor transport method using iodine as the transporting agent are studied here. The optical response of these crystals has been obtained by UV-Vis-NIR spectroscopy at room temperature. Results of optical spectra have been analyzed on the basis of three dimensional models. Photoelectrochemical (PEC) characterization of WTe 2 single crystals have been carried out. Photo response measurements were obtained at different intensities of light source to illuminate the photoanode. The effect of intensity in the efficiency of PEC solar cell has been studied. The implications of the results have been discussed.

  20. Phase correction in two-crystal optical parametric oscillators

    SciTech Connect

    Armstron, D.J.; Alford, W.J.; Raymond, T.D.; Smith, A.V.

    1995-02-01

    The effect of the pump, signal, and idler wave phases on three-wave nonlinear parametric mixing is investigated in a series of single-pass-gain experiments. Measurements are made with two angle-tuned KTP crystals in a 532 nm pumped, walkoff-compensated, optical parametric amplifier that is seeded by an 800 nm cw diode laser. In one of the measurements the second crystal is orientated to have its effective nonlinearity d{sub eff.} of opposite sign to that of the first crystal, so that all mixing that occurred in the first crystal is cancelled by the second when the phase mismatch {Delta}k{sub crystal 1} = {Delta}k{sub crystal 2} = 0. Efficient two-crystal amplification is subsequently restored by selecting the correct phase relationship for the three waves entering the crystal by inserting a dispersive plate between the crystals. The experimental results are explained in a straightforward manner with diagrams involving the three input wave polarizations. These results demonstrate that walkoff-compensated geometries require phase correction to achieve efficient mixing in the second crystal whenever the nonlinear interaction involves two extraordinary waves (e-waves). One practical application of this work may be lower oscillation thresholds and enhanced performance in walkoff-compensated optical parametric oscillators which use two e-waves.

  1. Optical stress sensor based on electro-optic compensation for photoelastic birefringence in a single crystal

    SciTech Connect

    Li Changsheng

    2011-09-20

    An optical stress sensor is proposed by using a single crystal with both electro-optic and photoelastic effects. Different from previous crystal-based stress sensors, the proposed sensor is based on electro-optic compensation for stress-induced birefringence and does not need an additional quarter-wave plate or modulator, because the stress-sensing element is simultaneously used as an electro-optic compensator. Candidate sensing materials include electro-optic crystals of the 3 m symmetry group and all glass with large Kerr coefficients. A primary experiment has demonstrated that the stress-induced birefringence in lithium niobate crystal can be compensated by its electro-optic birefringence. The proposed stress sensor is compact and low cost, and it is possible to achieve closed-loop stress measurement.

  2. Rapid detection of Escherichia coli O157:H7 in ground beef using a fiber-optic biosensor.

    PubMed

    DeMarco, D R; Saaski, E W; McCrae, D A; Lim, D V

    1999-07-01

    A portable fiber-optic biosensor was used to detect Escherichia coli O157:H7 in seeded ground beef samples. The principle of the system is a sandwich immunoassay using cyanine 5 dye-labeled polyclonal anti-E. coli O157:H7 antibodies for generation of a specific fluorescent signal. Signal acquisition is effected by launching light from a 635-nm diode laser into a dual tapered 600-microm silica fiber. Fluorescent molecules within approximately 100 nm of the fiber surface are excited by the evanescent field, and a portion of the emission recouples into the fiber. A photodiode allows for quantitation of the collected emission light at wavelengths of 670 to 710 nm. Biotin-avidin interactions are used to attach polyclonal antibodies specific for E. coli O157:H7 to the final 7.5 cm of the fiber probe. The biosensor was able to detect E. coli O157:H7 to 3 to 30 CFU/ml in seeded ground beef samples. The reaction was highly specific. Signals with Listeria monocytogenes, Salmonella Typhimurium, or E. coli nonO157:H7 were 2 to 3% of those observed with a similar concentration of E. coli O157:H7. Assays were conducted at or near real-time with results obtained within 20 min of sampling. PMID:10419260

  3. Tunable optical anisotropy in three-dimensional photonic crystals

    SciTech Connect

    Che Ming; Li Zhiyuan; Liu Rongjuan

    2007-08-15

    Artificial optical birefringence can be realized in three-dimensional photonic crystals with a uniaxial structural symmetry: e.g., woodpile photonic crystals with a tetragonal lattice structure in the long-wavelength limit. The ordinary and extraordinary indices of refraction are determined from calculation of the reflection coefficient for a plane wave incident on the surface of a semi-infinite photonic crystal at different angles. We find that the anisotropy can be widely tuned by simply changing the width and thickness of the dielectric rod. A large relative negative anisotropy over 33% is found. A transition from positive anisotropy to negative anisotropy can be readily achieved. At certain parameters, a structurally anisotropic nanostructure can behave like an optically isotropic medium. Our study opens a window to use artificial nanostructures to create an arbitrary optical anisotropy that is not possible in natural crystals.

  4. Evolution of molecular crystal optical phonons near structural phase transitions

    NASA Astrophysics Data System (ADS)

    Michki, Nigel; Niessen, Katherine; Xu, Mengyang; Markelz, Andrea

    Molecular crystals are increasingly important photonic and electronic materials. For example organic semiconductors are lightweight compared to inorganic semiconductors and have inexpensive scale up processing with roll to roll printing. However their implementation is limited by their environmental sensitivity, in part arising from the weak intermolecular interactions of the crystal. These weak interactions result in optical phonons in the terahertz frequency range. We examine the evolution of intermolecular interactions near structural phase transitions by measuring the optical phonons as a function of temperature and crystal orientation using terahertz time-domain spectroscopy. The measured orientation dependence of the resonances provides an additional constraint for comparison of the observed spectra with the density functional calculations, enabling us to follow specific phonon modes. We observe crystal reorganization near 350 K for oxalic acid as it transforms from dihydrate to anhydrous form. We also report the first THz spectra for the molecular crystal fructose through its melting point.

  5. A novel organic nonlinear optical crystal: Creatininium succinate

    NASA Astrophysics Data System (ADS)

    Thirumurugan, R.; Anitha, K.

    2015-06-01

    A novel organic material complex of creatininium succinate (CS) has been synthesized and single crystals were grown by the reaction of creatinine and succinic acid from aqueous solution by employing the technique of slow evaporation at room temperature. The structure of the grown crystal has been elucidated using single crystal X-ray diffraction analysis and the structure was refined by least-squares method to R = 0.027 for 1840 reflections. FT-IR spectral investigation has been carried out to identify the various functional groups in the title compound. UV-Vis transmission was carried out which shows the crystal has a good optical transmittance in the visible region with lower cutoff wavelength around 220 nm. Nonlinear optical property of the crystal was confirmed by Kurtz-Perry powder technique.

  6. Crystal growth of organics for nonlinear optical applications

    NASA Technical Reports Server (NTRS)

    Singh, N. B.; Mazelsky, R.

    1993-01-01

    The crystal growth and characterization of organic and inorganic nonlinear optical materials were extensively studied. For example, inorganic crystals such as thallium arsenic selenide were studied in our laboratory for several years and crystals in sizes over 2.5 cm in diameter are available. Organic crystals are suitable for the ultraviolet and near infrared region, but are relatively less developed than their inorganic counterparts. Very high values of the second harmonic conversion efficiency and the electro-optic coefficient were reported for organic compounds. Single crystals of a binary organic alloy based on m.NA and CNA were grown and higher second harmonic conversion efficiency than the values reported for m.NA were observed.

  7. A novel organic nonlinear optical crystal: Creatininium succinate

    SciTech Connect

    Thirumurugan, R.; Anitha, K.

    2015-06-24

    A novel organic material complex of creatininium succinate (CS) has been synthesized and single crystals were grown by the reaction of creatinine and succinic acid from aqueous solution by employing the technique of slow evaporation at room temperature. The structure of the grown crystal has been elucidated using single crystal X-ray diffraction analysis and the structure was refined by least-squares method to R = 0.027 for 1840 reflections. FT-IR spectral investigation has been carried out to identify the various functional groups in the title compound. UV–Vis transmission was carried out which shows the crystal has a good optical transmittance in the visible region with lower cutoff wavelength around 220 nm. Nonlinear optical property of the crystal was confirmed by Kurtz-Perry powder technique.

  8. Process of making cryogenically cooled high thermal performance crystal optics

    SciTech Connect

    Kuzay, T.M.

    1990-06-29

    A method for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N{sub 2} is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation.

  9. Process of making cryogenically cooled high thermal performance crystal optics

    DOEpatents

    Kuzay, T.M.

    1992-06-23

    A method is disclosed for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N[sub 2] is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation. 7 figs.

  10. Process of making cryogenically cooled high thermal performance crystal optics

    DOEpatents

    Kuzay, Tuncer M.

    1992-01-01

    A method for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N.sub.2 is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation.

  11. Open loop liquid crystal adaptive optics systems: progresses and results

    NASA Astrophysics Data System (ADS)

    Cao, Zhao-liang; Mu, Quan-quan; Xu, Huan-yu; Zhang, Pei-guang; Yao, Li-shuang; Xuan, Li

    2015-10-01

    Liquid crystal wavefront corrector (LCWFC) is one of the most attractive wavefront correction devices for adaptive optics system. The main disadvantages for conventional nematic LCWFC are polarization dependence and narrow working waveband. In this paper, a polarized beam splitter (PBS) based open loop optical design and an optimized energy splitting method was used to overcome these problems respectively. The results indicate that the open loop configuration was suitable for LCWFC and the novel energy splitting method can significantly improve the detection capability of the liquid crystal adaptive optics system.

  12. Laser-induced microwave generation with nonlinear optical crystals

    NASA Astrophysics Data System (ADS)

    Borghesani, Francesco; Braggio, Caterina; Carugno, Giovanni; Della Valle, Federico; Ruoso, Giuseppe

    2014-05-01

    We report about a novel technique to generate microwave radiation by the irradiation of a nonlinear optical crystal with uniformly spaced, ultrashort optical pulses delivered by a mode-locked laser. We study systematically the laser polarization and intensity dependence of the microwave signal to conclusively show that it is a nonlinear phenomenon and that it originates from optical rectification. The measurements have been conducted using KTP, LBO and ZnSe crystals. The observed pulsed microwave signals are harmonically related to the laser pulses repetition rate, a feature that can be exploited to develop an innovative ultrafast laser detector.

  13. The liquid crystal light valve, an optical-to-optical interface device

    NASA Technical Reports Server (NTRS)

    Jacobson, A. D.; Beard, T. D.; Bleha, W. P.; Margerum, J. D.; Wong, S. Y.

    1972-01-01

    A photoactivated liquid crystal light valve is described as an optical-to-optical interface device (OTTO) which is designed to transfer an optical image from a noncoherent light beam to a spatially coherent beam of light, in real time. Schematics of OTTO in use, the liquid cyrstal cell, and the liquid crystal structure are presented. Sensitivity characteristics and the principles of operation are discussed.

  14. Nonlinear optics, active plasmonics and metamaterials with liquid crystals

    NASA Astrophysics Data System (ADS)

    Khoo, Iam Choon

    2014-03-01

    Nematic liquid crystals possess large and versatile optical nonlinearities suitable for photonics applications spanning the femtoseconds to milliseconds time scales, and across a wide spectral window. We present a comprehensive review of the physical properties and mechanisms that underlie these multiple time scales nonlinearities, delving into individual molecular electronic responses as well as collective ordered-phase dynamical processes. Several exemplary theoretical formalisms and feasibility demonstrations of ultrafast all-optical transmission switching and tunable metamaterials and plasmonic photonic structures where the liquid crystal constituents play the critical role of enabling the processes are discussed. Emphasis is placed on all-optical processes, but we have also highlighted cases where electro-optical means could provide additional control, flexibility and enhancement possibility. We also point out how another phase of chiral nematic, namely, Blue-Phase liquid crystals could circumvent some of the limitations of nematic and present new possibilities.

  15. Single Crystal Sapphire Optical Fiber Sensor Instrumentation

    SciTech Connect

    Anbo Wang; Russell May; Gary R. Pickrell

    2000-10-28

    The goal of this 30 month program is to develop reliable accurate temperature sensors based on single crystal sapphire materials that can withstand the temperatures and corrosive agents present within the gasifier environment. The research for this reporting period has been segregated into two parallel paths--corrosion resistance measurements for single crystal sapphire fibers and investigation of single crystal sapphire sensor configurations. The ultimate goal of this phase one segment is to design, develop and demonstrate on a laboratory scale a suitable temperature measurement device that can be field tested in phase two of the program.

  16. Non-linear optical crystal vibration sensing device

    DOEpatents

    Kalibjian, R.

    1994-08-09

    A non-linear optical crystal vibration sensing device including a photorefractive crystal and a laser is disclosed. The laser produces a coherent light beam which is split by a beam splitter into a first laser beam and a second laser beam. After passing through the crystal the first laser beam is counter-propagated back upon itself by a retro-mirror, creating a third laser beam. The laser beams are modulated, due to the mixing effect within the crystal by vibration of the crystal. In the third laser beam, modulation is stable and such modulation is converted by a photodetector into a usable electrical output, intensity modulated in accordance with vibration applied to the crystal. 3 figs.

  17. Non-linear optical crystal vibration sensing device

    DOEpatents

    Kalibjian, Ralph

    1994-01-11

    A non-linear optical crystal vibration sensing device (10) including a photorefractive crystal (26) and a laser (12). The laser (12 ) produces a coherent light beam (14) which is split by a beam splitter (18) into a first laser beam (20) and a second laser beam (22). After passing through the crystal (26) the first laser beam (20) is counter-propagated back upon itself by a retro-mirror (32), creating a third laser beam (30). The laser beams (20, 22, 30) are modulated, due to the mixing effect within the crystal (26) by vibration of the crystal (30). In the third laser beam (30), modulation is stable and such modulation is converted by a photodetector (34) into a usable electrical output, intensity modulated in accordance with vibration applied to the crystal (26).

  18. Second-Order Nonlinear Optical Imaging of Chiral Crystals

    PubMed Central

    Kissick, David J.; Wanapun, Debbie; Simpson, Garth J.

    2012-01-01

    Second-order nonlinear optical imaging of chiral crystals (SONICC) is an emerging technique for crystal imaging and characterization. We provide a brief overview of the origin of second harmonic generation signals in SONICC and discuss recent studies using SONICC for biological applications. Given that they provide near-complete suppression of any background, SONICC images can be used to determine the presence or absence of protein crystals through both manual inspection and automated analysis. Because SONICC creates high-resolution images, nucleation and growth kinetics can also be observed. SONICC can detect metastable, homochiral crystalline forms of amino acids crystallizing from racemic solutions, which confirms Ostwald’s rule of stages for crystal growth. SONICC’s selectivity, based on order, and sensitivity, based on background suppression, make it a promising technique for numerous fields concerned with chiral crystal formation. PMID:21469954

  19. Surface mediated nonlinear optic effects in liquid crystals

    NASA Astrophysics Data System (ADS)

    Merlin, Jessica M.

    Liquid crystals have become a significant part of technology, mainly through their use in the display industry. This is due in part to the fact that the optical properties of liquid crystals are easily manipulated electronically. It has been recognized that the optical properties liquid crystals may also be controlled using light. Because of this, there are other various applications being explored for liquid crystals in photorefraction, optical limiting and switching, and in spatial light modulators. Although, the photorefractive effect was reported in liquid crystals over 10 years ago, there is still controversy over the exact mechanism for the reorientation of the liquid crystal director. This difficulty may be due in part to the fact that it is difficult to characterize the effect using photorefractive measurements and figures of merit. The optical and electronic control of liquid crystals will be studied here using a Friedericksz transition measurement in a twist cell geometry. This type of apparatus was chosen because it leads to a more direct demonstration of the surface effect. Namely, by studying changes in the Friedericksz transition threshold in a twist cell, a more direct observation of changes in the internal field may be observed. First a brief introduction to liquid crystals and their role in technology will be presented. This will be followed by a more rigorous discussion of the physics of liquid crystals and a review of the important literature. The experimental apparatus and the materials and cell geometry used will be described followed by the results of those measurements. Finally, the results will be considered in terms of a model involving interfacial charge and discussed in the context of previous work.

  20. Crystal growth and characterization of new semiorganic nonlinear optical single crystals

    NASA Astrophysics Data System (ADS)

    Kulshrestha, Shobha; Shrivastava, A. K.

    2016-05-01

    An organic material of a L-histidine monohydrochloride single crystal was grown in a distilled water solution using the slow evaporation method at 40-45°C. The grown crystal was transparent and colourless, with a size of about 20 × 9 × 5 mm3, obtained within a period of 21 days. The solubility of grown crystals have found out at various temperatures. The UV-visible transmittance studies show that the grown crystals have wide optical transparency in the entire visible region It is observed that the crystal has transparency window from 255nm to 700nm and its energy gap (Eg) found to be is 3.1eV. The grown crystal was subjected to powder X-ray diffraction analysis, confirming that the orthorhombic crystalline nature of the crystal. To identify the surface morphology, the as grown crystal was subjected to FE-SEM technique. The chemical composition of the grown crystal was estimated by Energy dispersive X-ray analysis. The optical behaviour of the grown crystal was analyzed by PL study.

  1. Synthesis, crystal growth and characterization of nonlinear optical organic crystal: p-Toluidinium p-toluenesulphonate

    SciTech Connect

    Vijayakumar, P.; Anandha Babu, G.; Ramasamy, P.

    2012-04-15

    Graphical abstract: p-Toluidinium p-toluenesulphonate (p-TTS) an organic nonlinear optical crystal has been grown from the aqueous solution by slow evaporation solution growth technique. Single crystal X-ray diffraction analysis reveals that p-TTS crystallizes in monoclinic crystal system. p-TTS single crystal belongs to negative birefringence crystal. Second harmonic conversion efficiency of p-TTS has been found to be 1.3 times higher than that of KDP. Multiple shot surface laser damage threshold is determined to be 0.30 GW/cm{sup 2} at 1064 nm laser radiation. Highlights: Black-Right-Pointing-Pointer It deals with the synthesis, growth and characterization of p-TTS an organic NLO crystal. Black-Right-Pointing-Pointer Wide optical transparency window between 280 nm and 1100 nm. Black-Right-Pointing-Pointer Negative birefringence crystal and dispersion of birefringence is negligibly small. Black-Right-Pointing-Pointer Thermal study reveals that the grown crystal is stable up to 210 Degree-Sign C. Black-Right-Pointing-Pointer Multiple shot surface laser damage threshold is 0.30 GW/cm{sup 2} at 1064 nm laser radiation. -- Abstract: p-Toluidinium p-toluenesulphonate (p-TTS) an organic nonlinear optical crystal has been grown from the aqueous solution by slow evaporation solution growth technique. Single crystal X-ray diffraction analysis reveals that p-TTS crystallizes in monoclinic crystal system. The structural perfection of the grown p-TTS single crystal has been analyzed by high-resolution X-ray diffraction rocking curve measurements. Fourier transform infrared spectral studies have been performed to identify the functional groups. The optical transmittance window and the lower cutoff wavelength of the grown crystals have been identified by UV-vis-IR studies. Birefringence of p-TTS crystal has been studied using channel spectrum measurement. The laser damage threshold value was measured using Nd:YAG laser. The second harmonic conversion efficiency of p-TTS has

  2. Engineering closed optical transitions in rare-earth ion crystals

    NASA Astrophysics Data System (ADS)

    Bartholomew, John G.; Ahlefeldt, Rose L.; Sellars, Matthew J.

    2016-01-01

    We propose a protocol to preserve the spin state of rare-earth ions when they are optically cycled. This technique uses large magnetic fields to increase the probability of an optically excited ion returning to its initial spin state. This Zeeman enhanced cyclicity is shown to be applicable to non-Kramers ions in various crystals irrespective of the site symmetry. The specific example of Pr3 +:Y2SiO5 is investigated to demonstrate that the protocol can create closed optical transitions even where the point group symmetry of the site is C1. In this example, the predicted cyclicity exceeds 104. This high level of cyclicity extends the usefulness of rare-earth ion crystals for applications in quantum and classical information processing. We explore the use of this technique to enable single-ion, spin-state optical readout and the creation of ensemble-based spectral features that are robust against optical cycling.

  3. Genomagnetic Electrochemical Biosensors

    NASA Astrophysics Data System (ADS)

    Wang, Joseph; Erdem, Arzum

    The use of nucleic acid technologies has significantly improved preparation and diagnostic procedures in life sciences. Nucleic acid layers combined with electrochemical or optical transducers produce a new kind of affinity biosensors as DNA Biosensor for small molecular weight molecules. Electrochemical DNA biosensors are attractive devices for converting the hybridization event into an analytical signal for obtaining sequence-specific information in connection with clinical, environmental or forensic investigations. DNA hybridization biosensors, based on electrochemical transduction of hybridization, couple the high specificity of hybridization reactions with the excellent sensitivity and portability of electrochemical transducers. The main goal in all researches is to design DNA biosensors for preparing a basis for the future DNA microarray system. DNA chip has now become a powerful tool in biological research, however the real clinic assay is still under development. Recently, there has been a great interest to the magnetic beads and/or nanoparticles labelled with metals such as gold, cadmium, silver, etc. for designing of novel electrochemical DNA biosensor approaches resulting in efficient separation. The attractive features of this technology include simple approach, rapid results, multi-analyte detection, low-cost per measurument, stable, and non-hazardous reagents, and reduced waste handling. Some of these new approaches and applications of the electrochemical DNA biosensors based on magnetic beads and its combining with nanoparticles labelled with metals are described and discussed.

  4. Reporter Proteins in Whole-Cell Optical Bioreporter Detection Systems, Biosensor Integrations, and Biosensing Applications

    PubMed Central

    Close, Dan M.; Ripp, Steven; Sayler, Gary S.

    2009-01-01

    Whole-cell, genetically modified bioreporters are designed to emit detectable signals in response to a target analyte or related group of analytes. When integrated with a transducer capable of measuring those signals, a biosensor results that acts as a self-contained analytical system useful in basic and applied environmental, medical, pharmacological, and agricultural sciences. Historically, these devices have focused on signaling proteins such as green fluorescent protein, aequorin, firefly luciferase, and/or bacterial luciferase. The biochemistry and genetic development of these sensor systems as well as the advantages, challenges, and common applications of each one will be discussed. PMID:22291559

  5. Optical properties of borate crystals in terahertz region

    NASA Astrophysics Data System (ADS)

    Antsygin, V. D.; Mamrashev, A. A.; Nikolaev, N. A.; Potaturkin, O. I.; Bekker, T. B.; Solntsev, V. P.

    2013-11-01

    In this paper we study the optical properties of a family of borate crystals comprising alpha and beta barium borates, barium fluoroborate, lithium triborate, and lithium tetraborate in the frequency range from 0.3 to 2.0 THz. We extract the refractive indices and absorption coefficients for both ordinary and extraordinary beams from terahertz time-domain spectroscopy data. All of the investigated crystals exhibit substantial birefringence and dichroism, which qualifies them as potential materials for terahertz polarization-optical devices. We also find an additional absorption band in barium borate crystals, which is not defined by the group of phonon modes lying above 2 THz. We argue that this phenomenon may be caused by excessive sodium atoms and ions in the crystal lattice.

  6. Nonreciprocal optical properties in resonant hybrid photonic crystals

    NASA Astrophysics Data System (ADS)

    D'Andrea, A.; Tomassini, N.

    2016-07-01

    The present work is devoted to the theoretical study of the nonreciprocal optical properties in hybrid (isotropic and anisotropic) periodic multilayers for photon energy values chosen close to the electronic energy gaps of semiconductors (excitons). The optical properties of these resonant nonmagnetic photonic crystals, where linear and quadratic spatial dispersion effects are both present, will be studied in the framework of exciton-polariton self-consistent solutions of the Maxwell and Schrödinger equations in the effective-mass approximation. The main interesting optical properties, namely, giant transmission, absorption suppression, and optical unidirectional propagation, will be computed by implementing a two-layer "minimum model."

  7. Crystal structure, growth and nonlinear optical studies of isonicotinamide p-nitrophenol: A new organic crystal for optical limiting applications

    NASA Astrophysics Data System (ADS)

    Vijayalakshmi, A.; Vidyavathy, B.; Vinitha, G.

    2016-08-01

    Isonicotinamide p-nitrophenol (ICPNP), a new organic material, was synthesized using methanol solvent. Single crystals of ICPNP were grown using a slow evaporation solution growth technique. Crystal structure of ICPNP is elucidated by single crystal X-ray diffraction analysis. It belongs to monoclinic crystal system with space group of P21/c. It forms two dimensional networks by O-H…O, N-H…O and C-H…O hydrogen bonds. The molecular structure of ICPNP was further confirmed by Fourier transform infrared (FTIR) spectral analysis. The optical transmittance range and the lower cut-off wavelength (421 nm) with the optical band gap (2.90 eV) of the ICPNP crystal were determined by UV-vis-NIR spectral study. Thermal behavior of ICPNP was studied by thermo gravimetric and differential thermal analyses (TG/DTA). The relative dielectric permittivity was calculated for various temperature ranges. Laser damage threshold of ICPNP crystal was found to be 1.9 GW/cm2 using an Nd:YAG laser. A Z-scan technique was employed to measure the nonlinear absorption coefficient, nonlinear refractive index and nonlinear optical susceptibility. Optical limiting behavior of ICPNP was observed at 35 mW input power.

  8. Optical modulator based on coupled photonic crystal cavities

    NASA Astrophysics Data System (ADS)

    Serafimovich, Pavel G.; Kazanskiy, Nikolay L.

    2016-07-01

    We propose and numerically investigate an optical signal modulator based on two-photonic crystal nanobeam cavities coupled through a waveguide. The suggested modulator shifts the resonant frequency over a scalable range. We design a compact optical modulator based on photonic crystal nanobeams cavities that exhibits high stability to manufacturing. Photonic crystal waveguide tuning in the low-intensity region of the resonant mode is demonstrated. The advantages of the suggested approach over the single-resonator optical modulator approaches include the possibilities to shift the modulator frequency over a scalable range that depends on switching energy level and to effectively electrically tune the device in the low-intensity region of the resonant mode.

  9. Label-free optical biosensor for detection and quantification of the non-steroidal anti-inflammatory drug diclofenac in milk without any sample pretreatment.

    PubMed

    Rau, Sabrina; Hilbig, Urs; Gauglitz, Günter

    2014-05-01

    A label-free optical biosensor for detection and quantification of diclofenac in bovine milk has been developed. This was achieved by using reflectometric interference spectroscopy as detection method. In a first step, the immunosensor was developed and optimised in buffer concerning sensitivity, selectivity, stability and reproducibility. By comparing recovery rates—not only the good intra- but also the good inter-chip—reproducibility could be proven. Consequently, the assay was transferred in the more complex matrix milk. By utilising an optimised surface modification and evaluation method, matrix effects could successfully be prevented or circumvented. As a result, the developed immunosensor does not need sample pretreatment at all. By obtaining a limit of detection of 0.112 μg L(−1) (0.108 μg kg(−1)), the capability of the developed biosensor is comparable or better than those of standard detection methods. Moreover, the presented biosensor reaches the range of the maximum residue limit (0.1 μg kg(−1)) set by the European Union. Thus, for the first time, diclofenac was successfully quantified at relevant levels in milk by using an optical biosensor. PMID:24658575

  10. Electro-optic crystal mosaics for the generation of terahertz radiation

    DOEpatents

    Carrig, Timothy J.; Taylor, Antoinette J.; Stewart, Kevin R.

    1996-01-01

    Apparatus for the generation of high energy terahertz radiation is presented and comprises laser means effective to produce subpicosecond optical pulses and a mosaic comprising a plurality of planar electro-optic crystals fastened together edge to edge in the form of a grid. The electro-optic crystals are in optical communication with the subpicosecond optical pulses, and behave as a single large electro-optic crystal, producing high energy terahertz radiation by way of optical rectification.

  11. Electro-optic crystal mosaics for the generation of terahertz radiation

    DOEpatents

    Carrig, T.J.; Taylor, A.J.; Stewart, K.R.

    1996-08-06

    Apparatus for the generation of high energy terahertz radiation is presented and comprises laser means effective to produce subpicosecond optical pulses and a mosaic comprising a plurality of planar electro-optic crystals fastened together edge to edge in the form of a grid. The electro-optic crystals are in optical communication with the subpicosecond optical pulses, and behave as a single large electro-optic crystal, producing high energy terahertz radiation by way of optical rectification. 5 figs.

  12. Modeling of Optical Aberration Correction using a Liquid Crystal Device

    NASA Technical Reports Server (NTRS)

    Xinghua, Wang; Bin, Wang; McManamon, Paul F.; Pouch, John J.; Miranda, Felix A.

    2006-01-01

    Gruneisen (sup 1-3), has shown that small, light weight, liquid crystal based devices can correct for the optical distortion caused by an imperfect primary mirror in a telescope and has discussed the efficiency of this correction. In this paper we expand on that work and propose a semi-analytical approach for quantifying the efficiency of a liquid crystal based wavefront corrector for this application.

  13. Thermal, optical and spectroscopic characterizations of borate laser crystals

    NASA Astrophysics Data System (ADS)

    Chavoutier, M.; Jubera, V.; Veber, P.; Velazquez, M.; Viraphong, O.; Hejtmanek, J.; Decourt, R.; Debray, J.; Menaert, B.; Segonds, P.; Adamietz, F.; Rodriguez, V.; Manek-Hönninger, I.; Fargues, A.; Descamps, D.; Garcia, A.

    2011-02-01

    The Yb-content Li 6Ln(BO 3) 3 ( Ln: Gd, Y) solid solution has been investigated. Crystal growth has been successful for several compositions. A 22% molar content of ytterbium ions was determined by chemical analysis (ICP). Physical properties relevant to laser operation like mechanical hardness, thermal expansion and thermal conductivity were measured on single crystals. Optical measurements, including refractive index and low temperature spectroscopy, were also performed. Finally, the effect of the Y/Gd ratio is discussed.

  14. Three-dimensional metallic photonic crystals with optical bandgaps.

    PubMed

    Vasilantonakis, Nikos; Terzaki, Konstantina; Sakellari, Ioanna; Purlys, Vytautas; Gray, David; Soukoulis, Costas M; Vamvakaki, Maria; Kafesaki, Maria; Farsari, Maria

    2012-02-21

    The fabrication of fully three-dimensional photonic crystals with a bandgap at optical wavelengths is demonstrated by way of direct femtosecond laser writing of an organic-inorganic hybrid material with metal-binding moieties, and selective silver coating using electroless plating. The crystals have 600-nm intralayer periodicity and sub-100 nm features, and they exhibit well-defined diffraction patterns. PMID:22278944

  15. Liquid Crystal Droplet-Embedded Biopolymer Hydrogel Sheets for Biosensor Applications.

    PubMed

    Deng, Jinan; Liang, Wenlang; Fang, Jiyu

    2016-02-17

    The development of simple, portable, and low-cost biosensing platforms is of great interest in the clinical diagnosis of disease. Here, we report liquid crystal (LC) droplet-embedded chitosan (CHI) hydrogel films formed by the Ag(+) ion-triggered fast gelation of the CHI/surfactant complex-stabilized LC emulsion which is cast on substrates. The small sheets cut from the LC droplet-embedded hydrogel films combine the advantages of both hydrogels and LC droplets, offering a portable and label-free sensing platform for the real-time detection of bile acids in a small amount of solution. We find that the response time and detection limit of LC droplet-embedded hydrogel sheets for bile acids depend on their chemical structures. PMID:26808341

  16. An Integrative Biosensor Based on Contra-Directional Coupling Two-dimensional Photonic Crystal Waveguides

    NASA Astrophysics Data System (ADS)

    Mao, Xiao-Yu; Yao, Di-Bi; Zhao, Ling-Yun; Huang, Yi-Dong; Zhang, Wei; Peng, Jiang-De

    2008-01-01

    We propose an integrative biochemical sensor utilizing the dip in the transmission spectrum of a normal single-line defect photonic crystal (PC) waveguide, which has a contra-directional coupling with another PC waveguide. When the air holes in the PC slab are filled with a liquid analyte with different refractive indices, the dip has a wavelength shift By detecting the output power variation at a certain fixed wavelength, a sensitivity of 1.2 × 10-4 is feasible. This structure is easy for integration due to its plane waveguide structure and omissible pump source. In addition, high signal to noise ratio can be expected because signal transmits via a normal single-line defect PC waveguide instead of the PC hole area or analyte.

  17. Growth and nonlinear optical characterization of organic single crystal films

    NASA Astrophysics Data System (ADS)

    Zhou, Ligui

    1997-12-01

    Organic single crystal films are important for various future applications in photonics and integrated optics. The conventional method for inorganic crystal growth is not suitable for organic materials, and the high temperature melting method is not good for most organic materials due to decomposition problems. We developed a new method-modified shear method-to grow large area organic single crystal thin films which have exceptional nonlinear optical properties and high quality surfaces. Several organic materials (NPP, PNP and DAST) were synthesized and purified before the thin film crystal growth. Organic single crystal thin films were grown from saturated organic solutions using modified shear method. The area of single crystal films were about 1.5 cm2 for PNP, 1 cm2 for NPP and 5 mm2 for DAST. The thickness of the thin films which could be controlled by the applied pressure ranged from 1μm to 10 μm. The single crystal thin films of organic materials were characterized by polarized microscopy, x-ray diffraction, polarized UV-Visible and polarized micro-FTIR spectroscopy. Polarized microscopy showed uniform birefringence and complete extinction with the rotation of the single crystal thin films under crossed- polarization, which indicated high quality single crystals with no scattering. The surface orientation of single crystal thin films was characterized by x-ray diffraction. The molecular orientation within the crystal was further studied by the polarized UV-Visible and Polarized micro-FTIR techniques combined with the x-ray and polarized microscopy results. A Nd:YAG laser with 35 picosecond pulses at 1064nm wavelength was employed to perform the nonlinear optical characterization of the organic single crystal thin films. Two measurement techniques were used to study the crystal films: second harmonic generation (SHG) and electro-optic (EO) effect. SHG results showed that the nonlinear optical coefficient of NPP was 18 times that of LiNbO3, a standard

  18. Optically induced melting of colloidal crystals and their recrystallization.

    PubMed

    Harada, Masashi; Ishii, Masahiko; Nakamura, Hiroshi

    2007-04-15

    Colloidal crystals melt by applying focused light of optical tweezers and recrystallize after removing it. The disturbed zone by the light grows radially from the focus point and the ordering starts from the interface with the crystal. Although the larger disturbed zone is observed for the higher power optical tweezers, a master curve is extracted by normalization of the disturbed zone. The temporal changes of the normalized disturbed zone are well described with exponential functions, indicating that the melting and recrystallization process is governed by a simple relaxation mechanism. PMID:17049820

  19. Optical Properties of TGS Crystal with L-Valine Admixture

    SciTech Connect

    Stadnyk, V. Yo. Romanyuk, N. A.; Kiryk, Yu. I.

    2010-11-15

    The thermal expansion and temperature and the spectral dependences of the refractive indices and birefringence of triglycine sulphate (TGS) crystals with a 5% L-valine admixture have been investigated. It is established that the introduction of L-valine weakens the temperature dependence of the refractive indices and the birefringence and thermal expansion of TGS crystals. The parameters of the Sellmeier formula, refractions, and electronic polarizabilities are calculated. The changes observed may be related to the increase in hardness of admixture-containing crystals, the decrease in the spontaneous polarization, the replacement of the refraction components of the valine bond, or the spontaneous electro-optic effect.

  20. Optical Properties of TGS Crystal with L-Valine Admixture

    NASA Astrophysics Data System (ADS)

    Stadnyk, V. Yo.; Romanyuk, N. A.; Kiryk, Yu. I.

    2010-11-01

    The thermal expansion and temperature and the spectral dependences of the refractive indices and birefringence of triglycine sulphate (TGS) crystals with a 5% L-valine admixture have been investigated. It is established that the introduction of L-valine weakens the temperature dependence of the refractive indices and the birefringence and thermal expansion of TGS crystals. The parameters of the Sellmeier formula, refractions, and electronic polarizabilities are calculated. The changes observed may be related to the increase in hardness of admixture-containing crystals, the decrease in the spontaneous polarization, the replacement of the refraction components of the valine bond, or the spontaneous electro-optic effect.

  1. Optical-diffraction method for determining crystal orientation

    DOEpatents

    Sopori, B.L.

    1982-05-07

    Disclosed is an optical diffraction technique for characterizing the three-dimensional orientation of a crystal sample. An arbitrary surface of the crystal sample is texture etched so as to generate a pseudo-periodic diffraction grating on the surface. A laser light beam is then directed onto the etched surface, and the reflected light forms a farfield diffraction pattern in reflection. Parameters of the diffraction pattern, such as the geometry and angular dispersion of the diffracted beam are then related to grating shape of the etched surface which is in turn related to crystal orientation. This technique may be used for examining polycrystalline silicon for use in solar cells.

  2. Photonic crystal chips for optical communications and quantum information processing

    NASA Astrophysics Data System (ADS)

    Englund, Dirk; Fushman, Ilya; Faraon, Andrei; Ellis, Bryan; Vučković, Jelena

    2008-08-01

    We discuss recent our recent progress on functional photonic crystals devices and circuits for classical and quantum information processing. For classical applications, we have demonstrated a room-temperature-operated, low threshold, nanocavity laser with pulse width in the picosecond regime; and an all-optical switch controlled with 60 fJ pulses that shows switching time on the order of tens of picoseconds. For quantum information processing, we discuss the promise of quantum networks on multifunctional photonic crystals chips. We also discuss a new coherent probing technique of quantum dots coupled to photonic crystal nanocavities and demonstrate amplitude and phase nonlinearities realized with control beams at the single photon level.

  3. Highly Non-Linear Optical (NLO) organic crystals

    NASA Technical Reports Server (NTRS)

    Harris, J. Milton

    1987-01-01

    This research project involves the synthesis and characterization of organic materials having powerful nonlinear optical (NLO) properties and the growth of highly ordered crystals and monomolecular films of these materials. Research in four areas is discussed: theoretical design of new materials, characterization of NLO materials, synthesis of new materials and development of coupling procedures for forming layered films, and improvement of the techniques for vapor phase and solution phase growth of high quality organic crystals. Knowledge gained from these experiments will form the basis for experiments in the growth of these crystals.

  4. Phenomenological study of binding in optically trapped photonic crystals

    NASA Astrophysics Data System (ADS)

    Maystre, D.; Vincent, P.

    2007-08-01

    We describe a phenomenological theory of the phenomenon of binding observed both experimentally and numerically when particles are trapped by an interference system in order to make a structure close to a photonic crystal. This theory leads to a very simple conclusion, which links the binding phenomenon to the bottom of the lowest bandgap of the trapped crystal in a given direction. The phenomenological theory allows one to calculate the period of the trapped crystal by using numerical tools on dispersion diagrams of photonic crystals. It emerges that the agreement of our theory with our rigorous numerical results given in a previous paper [J. Opt A8, 1059 (2006)] is better than 2% on the crystal period. Furthermore, it is shown that in two-dimensional problems and s polarization, all the optical forces derive from a scalar potential.

  5. Label-free optical detection of C-reactive protein by nanoimprint lithography-based 2D-photonic crystal film.

    PubMed

    Endo, Tatsuro; Kajita, Hiroshi; Kawaguchi, Yukio; Kosaka, Terumasa; Himi, Toshiyuki

    2016-06-01

    The development of high-sensitive, and cost-effective novel biosensors have been strongly desired for future medical diagnostics. To develop novel biosensor, the authors focused on the specific optical characteristics of photonic crystal. In this study, a label-free optical biosensor, polymer-based two-dimensional photonic crystal (2D-PhC) film fabricated using nanoimprint lithography (NIL), was developed for detection of C-reactive protein (CRP) in human serum. The nano-hole array constructed NIL-based 2D-PhC (hole diameter: 230 nm, distance: 230, depth: 200 nm) was fabricated on a cyclo-olefin polymer (COP) film (100 µm) using thermal NIL and required surface modifications to reduce nonspecific adsorption of target proteins. Antigen-antibody reactions on the NIL-based 2D-PhC caused changes to the surrounding refractive index, which was monitored as reflection spectrum changes in the visible region. By using surface modified 2D-PhC, the calculated detection limit for CRP was 12.24 pg/mL at an extremely short reaction time (5 min) without the need for additional labeling procedures and secondary antibody. Furthermore, using the dual-functional random copolymer, CRP could be detected in a pooled blood serum diluted 100× with dramatic reduction of nonspecific adsorption. From these results, the NIL-based 2D-PhC film has great potential for development of an on-site, high-sensitivity, cost-effective, label-free biosensor for medical diagnostics applications. PMID:27150702

  6. Optical phonon modes and crystal structure of NaLaF4 single crystals

    NASA Astrophysics Data System (ADS)

    Lage, Márcio Martins; Matinaga, Franklin Massami; Gesland, Jean-Yves; Moreira, Roberto Luiz

    2006-03-01

    Polarized Raman scattering and infrared reflectivity measurements have been used to investigate the crystal structure of Czochralski-grown NaLaF4 single crystals. The phonon symmetries, the simultaneous presence of polar modes in the infrared and Raman spectra, as well as the observation of piezoelectric resonance, helped us to identify the P6 group as the correct one for this crystal. This material belongs to a family of sodium lanthanide tetrafluorides (NaLnF4) crystals, whose photoluminescence efficiency is comparable to LiYF4. Therefore, NaLaF4 crystals may be important in the development of diode pumped up-conversion solid-state lasers. The number and behavior of the observed optical phonon modes were analyzed in terms of group theory predictions for the group symmetry found. A few anomalies in the phonon characteristics are discussed in terms of cationic disorder in the crystal lattice.

  7. Optical Properties of Irradiated Topaz Crystals

    NASA Astrophysics Data System (ADS)

    Skvortsova, V.; Mironova-Ulmane, N.; Trinkler, L.

    2015-04-01

    The results of an investigation of UV-Visible absorption and photoluminescence spectra of colorless topaz before and after neutron irradiation, natural blue topaz from Ukraine, and yellow topaz are presented. We assume that the absorption band ∼ 620 nm and broad emission band 300-700 nm in topaz crystals are associated with exchange interaction between a radiation defect (anion vacancies, which capture one or two electrons) and impurity ions Cr3+, Fe3+ and Mn2+.

  8. Optical microfiber-based photonic crystal cavity

    NASA Astrophysics Data System (ADS)

    Yu, Yang; Sun, Yi-zhi; Andrews, Steve; Li, Zhi-yuan; Ding, Wei

    2016-01-01

    Using a focused ion beam milling technique, we fabricate broad stop band (∼10% wide) photonic crystal (PhC) cavities in adiabatically-tapered silica fibers. Abrupt structural design of PhC mirrors efficiently reduces radiation loss, increasing the cavity finesse to ∼7.5. Further experiments and simulations verify that the remaining loss is mainly due to Ga ion implantation. Such a microfiber PhC cavity probably has potentials in many light-matter interaction applications.

  9. Optical cleaning of congruent lithium niobate crystals

    NASA Astrophysics Data System (ADS)

    Kösters, M.; Sturman, B.; Werheit, P.; Haertle, D.; Buse, K.

    2009-09-01

    Lithium niobate (LiNbO3), also called the `silicon of photonics', is indispensable in advanced photonics and nonlinear optics. For many applications, however, the material is too polluted by transition metals, which are unavoidable at the parts per million level. These impurities serve as sources and traps for photoelectrons, causing optical damage and hampering the usability of LiNbO3. Efforts have therefore been made to get rid of the photoexcitable electrons. Here we introduce a method termed `optical cleaning'. We show theoretically and experimentally that, if the material is heated to moderate temperatures, allowing ions to migrate and to maintain charge neutrality, an appropriately moving light beam pushes photoexcitable electrons out of the illuminated region like a brush, and provides exponential cleaning. This promises purification levels that are beyond the reach of current technologies.

  10. Role of point defects in optical damage of nonlinear crystals

    NASA Astrophysics Data System (ADS)

    Scripsick, Michael P.; Edwards, Gary J.

    1993-07-01

    We have initiated a program at West Virginia University to establish the properties of point defects that are relevant to the optical damage phenomena in KTP, BBO, and LBO crystals. Defects have been characterized using optical absorption, electron paramagnetic resonance (EPR), electron-nuclear double resonance (ENDOR), and luminescence techniques. Among the defects which have been observed are impurity ions (iron, platinum, hydrogen, etc.), trapped hole centers, and trapped electron centers.

  11. Polychromatic Optical Vortex Generation from Patterned Cholesteric Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Kobashi, Junji; Yoshida, Hiroyuki; Ozaki, Masanori

    2016-06-01

    Generation of optical vortices is described in cholesteric liquid crystals with a singular point in the spatial distribution of a helix phase. The phenomenon uses the fact that a Bragg reflected light phase varies in proportion to the spatial phase of the helix, both at normal and oblique incidences. Our proposal enables high-efficiency, polychromatic generation of optical vortices without the need of a cumbersome fabrication process and fine-tuning.

  12. Polychromatic Optical Vortex Generation from Patterned Cholesteric Liquid Crystals.

    PubMed

    Kobashi, Junji; Yoshida, Hiroyuki; Ozaki, Masanori

    2016-06-24

    Generation of optical vortices is described in cholesteric liquid crystals with a singular point in the spatial distribution of a helix phase. The phenomenon uses the fact that a Bragg reflected light phase varies in proportion to the spatial phase of the helix, both at normal and oblique incidences. Our proposal enables high-efficiency, polychromatic generation of optical vortices without the need of a cumbersome fabrication process and fine-tuning. PMID:27391724

  13. Comments on the paper: 'Optical reflectance, optical refractive index and optical conductivity measurements of nonlinear optics for L-aspartic acid nickel chloride single crystal'

    NASA Astrophysics Data System (ADS)

    Srinivasan, Bikshandarkoil R.; Naik, Suvidha G.; Dhavskar, Kiran T.

    2016-02-01

    We argue that the 'L-aspartic acid nickel chloride' crystal reported by the authors of the title paper (Optics Communications, 291 (2013) 304-308) is actually the well-known diaqua(L-aspartato)nickel(II) hydrate crystal.

  14. Structural and optical properties of a new chalcone single crystal

    NASA Astrophysics Data System (ADS)

    Rajesh Kumar, P. C.; Ravindrachary, V.; Janardhana, K.; Poojary, Boja

    2012-09-01

    A new nonlinear optical material 1-(4-methylthiophenyl)-3-(4-methoxyphenyl)prop-2-en-1-one with molecular formula C17H16O2S was synthesized by using the Claisen-Schmidt condensation reaction method. The Various functional groups present in the compound were identified using recorded FT-IR spectrum. The crystal growth parameters have been studied using solubility test and acetone is found to be a very good solvent for the crystal growth at an ambient temperature. The transparent high quality single crystals up to a size of 26×2×2 mm3 were grown using the slow evaporation solution growth technique. UV-visible study was carried out and the spectrum reveals that the crystal is transparent in the entire visible region and absorptive in the UV region. The refractive index is determined using Brewster's angle method. The optical energy band gap of the material is measured using Tauc's plot and the direct method. The single crystal XRD of MMPP crystal shows the following cell parameters: a=5.9626(2) Å, b=15.3022(6) Å, c=16.0385(7) Å, α=β=γ=90°, volume=1463.37(10) Å3 with a space group of Pna21. The compound MMPP exhibits optical nonlinearity (NLO) and its second order NLO efficiency is 3.15 times to that of urea. The effect of functional groups OCH3 and SCH3 on the non-linearity as well as the structural property of the compound has been discussed. The crystal is thermally stable. High NLO efficiency, good thermal stability, good transparency and ability to grow as a high quality single crystal make this material very attractive for opto-electronic applications.

  15. Propagation optical quarks after an uniaxial crystal: the experiment

    NASA Astrophysics Data System (ADS)

    Egorov, Yu. A.; Konovalenko, V. L.; Zinovev, A. O.; Anischenko, P. M.; Glumova, M. V.

    2013-12-01

    There is a lots of different papers reporting about the propagation of the different types of an optical beams in a uniaxial crystals are known by that time. This beams are: Lager-Gaussian and Bessel- Gaussian beams. It is common for all this types of beams, that if propagation axis and crystal axis coincides, and accident beam had a circular polarization, are can get type spiral type degenerated umbilici, which corresponds to the charge 2 optical vortex in the orthogonal polarized beam component, generated by crystal [1] (Fig 1). This generation accurse due to total angular momentum conservation law symmetry axis of the crystal. One to the changing of the spin momentum which is associated with the beam polarization, this leads to the orbital momentum changes that associated with topological charge of formed orthogonal circular component. Double charged optical vortex could be easily perturbed by tilting beam axis with respect to the crystal axis. If the tilt angles are small (<0.1°) central umbilici splits on two lemons and the surrounding ring umbilici splits on two pairs of monster-star. The further increasing of the tilt angle leads to the topological charge of circular components becomes, equal, and additional orbital moment correspond to the beam mass center displacement.

  16. Optical manipulation and imaging of assemblies of topological defects and colloids in liquid crystals

    NASA Astrophysics Data System (ADS)

    Trivedi, Rahul P.

    Liquid Crystals (LCs) have proven to be important for electro-optic device applications such as displays, spatial light modulators, non-mechanical beam-steerers, etc. Owing to their unique mechanical, electrical, and optical properties, they are also being explored for wide array of advanced technological applications such as biosensors, tunable lenses, distributed feedback lasers, muscle-like actuators, etc. The thesis explores LC media from the standpoint of controlling their elastic and optical properties by generating and manipulating assemblies of defects and colloidal particles. To achieve the goal of optically manipulating these configurations comprising defects and particles at microscale with an unprecedented control, and then to visualize the resultant molecular director patterns, requires development of powerful optical system. The thesis discusses design and implementation of such an integrated system capable of 3D holographic optical manipulation and multi-modal 3D imaging (in nonlinear optical modes like multiphoton fluorescence, coherent anti-Stokes Raman scattering, etc.) and how they are used to extensively study a vast number of LC based systems. Understanding of LCs and topological defects go hand in hand. Appreciation of defects leads to their precise control, which in turn can lead to applications. The thesis describes discovery of optically generated stable, quasiparticle-like, localized defect structures in a LC cell, that we call "Torons". Torons enable twist of molecules in three dimensions and resemble both Skyrmion-like and Hopf fibration features. Under different conditions of generation, we optically realize an intriguing variety of novel solitonic defect structures comprising rather complicated configurations of point and line topological defects. Introducing colloidal particles to LC systems imparts to these hybrid material system a fascinating degree of richness of properties on account of colloidal assemblies supported by networks

  17. Demonstrations of Some Optical Properties of Liquid Crystals.

    ERIC Educational Resources Information Center

    Nicastro, Anthony J.

    1983-01-01

    Discusses several properties of liquid crystal displays. Includes instructions for demonstrating liquid crystalline phase, ordering of the long axes of molecules along one direction, and electro-optic effects. The latter is accomplished with the use of an overhead projector following preparation of a sandwich cell. (JN)

  18. Screening of Protein Crystallization Trials by Second Order Nonlinear Optical Imaging of Chiral Crystals (SONICC)

    PubMed Central

    Haupert, Levi; Simpson, Garth

    2011-01-01

    Second order nonlinear optical imaging of chiral crystals (SONICC) is a promising new method for the sensitive and selective detection of protein crystals. Relevant general principles of second harmonic generation, which underpins SONICC, are reviewed. Instrumentation and methods for SONICC measurements are described and critically assessed in terms of performance trade-offs. Potential origins of false-positives and false-negatives are also discussed. PMID:22101350

  19. Rapid detection of Mycobacterium tuberculosis biomarkers in a sandwich immunoassay format using a waveguide-based optical biosensor.

    PubMed

    Mukundan, Harshini; Kumar, Sandeep; Price, Dominique N; Ray, Sonja M; Lee, Ye-Jin; Min, Seonyeong; Eum, Seokyong; Kubicek-Sutherland, Jessica; Resnick, Jesse M; Grace, W Kevin; Anderson, Aaron S; Hwang, Soo Hee; Cho, Sang Nae; Via, Laura E; Barry, Clifton; Sakamuri, Ramamurthy; Swanson, Basil I

    2012-09-01

    Early diagnosis of active tuberculosis (TB) remains an elusive challenge, especially in individuals with disseminated TB and HIV co-infection. Recent studies have shown a promise for the direct detection of pathogen-specific biomarkers such as lipoarabinomannan (LAM) for the diagnosis of TB in HIV-positive individuals. Currently, traditional immunoassay platforms that suffer from poor sensitivity and high non-specific interactions are used for the detection of such biomarkers. In this manuscript, we demonstrate the development of sandwich immunoassays for the direct detection of three TB-specific biomarkers, namely LAM, early secretory antigenic target 6 (ESAT6) and antigen 85 complex (Ag85), using a waveguide-based optical biosensor platform. Combining detection within the evanescent field of a planar optical waveguide with functional surfaces that reduce non-specific interactions allows for the ultra-sensitive and quantitative detection of biomarkers (an order of magnitude enhanced sensitivity, as compared to plate-based ELISA) in complex patient samples (urine, serum) within a short time. We also demonstrate the detection of LAM in urine from a small sample of subjects being treated for TB using this approach with excellent sensitivity and 100% corroboration with disease status. These results suggest that pathogen-specific biomarkers can be applied for the rapid and effective diagnosis of disease. It is likely that detection of a combination of biomarkers offers greater reliability of diagnosis, rather than detection of any single pathogen biomarker. NCT00341601. PMID:22710249

  20. An optical biosensor for detection of pathogen biomarkers from Shiga toxin-producing Escherichia coli in ground beef samples

    NASA Astrophysics Data System (ADS)

    Lamoureux, Loreen; Adams, Peter; Banisadr, Afsheen; Stromberg, Zachary; Graves, Steven; Montano, Gabriel; Moxley, Rodney; Mukundan, Harshini

    2014-03-01

    Shiga toxin-producing Escherichia coli (STEC) poses a serious threat to human health through the consumption of contaminated food products, particularly beef and produce. Early detection in the food chain, and discrimination from other non-pathogenic Escherichia coli (E. coli), is critical to preventing human outbreaks, and meeting current agricultural screening standards. These pathogens often present in low concentrations in contaminated samples, making discriminatory detection difficult without the use of costly, time-consuming methods (e.g. culture). Using multiple signal transduction schemes (including novel optical methods designed for amphiphiles), specific recognition antibodies, and a waveguide-based optical biosensor developed at Los Alamos National Laboratory, we have developed ultrasensitive detection methods for lipopolysaccharides (LPS), and protein biomarkers (Shiga toxin) of STEC in complex samples (e.g. beef lysates). Waveguides functionalized with phospholipid bilayers were used to pull down amphiphilic LPS, using methods (membrane insertion) developed by our team. The assay format exploits the amphiphilic biochemistry of lipoglycans, and allows for rapid, sensitive detection with a single fluorescent reporter. We have used a combination of biophysical methods (atomic force and fluorescence microscopy) to characterize the interaction of amphiphiles with lipid bilayers, to efficiently design these assays. Sandwich immunoassays were used for detection of protein toxins. Biomarkers were spiked into homogenated ground beef samples to determine performance and limit of detection. Future work will focus on the development of discriminatory antibodies for STEC serotypes, and using quantum dots as the fluorescence reporter to enable multiplex screening of biomarkers.

  1. Theoretical design of photonic crystal devices for integrated optical circuits

    NASA Astrophysics Data System (ADS)

    Mekis, Attila

    2000-12-01

    In this thesis we investigate novel photonic crystal devices that can be used as building blocks of all- optical circuits. We contrast the behavior of light in photonic crystal systems and in their traditional counterparts. We exhibit that bends in photonic crystals are able to transmit light with over 90% efficiency for large bandwidths and with 100% efficiency for specific frequencies. In contrast to traditional waveguides, bound states in photonic crystal waveguides can also exist in constrictions and above the cutoff frequency. We discuss how to lower reflections encountered when photonic crystal waveguides are terminated, both in an experimental setup as well as in numerical simulations. We show that light can be very efficiently coupled into and out of photonic crystal waveguides using tapered dielectric waveguides. In time-domain simulations of photonic crystal waveguides, spurious reflections from cell edges can be eliminated by terminating the waveguide with a Bragg reflector waveguide. We demonstrate novel lasing action in two-dimensional photonic crystal slabs with gain media, where lasing occurs at saddle points in the band structure, in contrast to one-dimensional photonic crystals. We also design a photonic crystal slab with organic gain media that has a TE-like pseudogap. We demonstrate that such a slab can support a high- Q defect mode, enabling low threshold lasing, and we discuss how the quality factor depends on the design parameters. We also propose to use two- dimensional photonic crystal slabs as directionally efficient free-space couplers. We draft methods to calculate the coupling constant both numerically and analytically, using a finite-difference time-domain method and the volume current method with a Green's function approach, respectively. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)

  2. Configuration of singular optical cones in gyrotropic crystals with dichroism

    SciTech Connect

    Merkulov, V. S.

    2015-02-15

    Optical conic singularities in crystals with linear dichroism and natural optical activity at the point of intersection of dispersion curves for the main refractive indices are considered. The possible existence of singularities like a nodal point, tangency point, triple point, and cusps of the first and second order is demonstrated. Forty-nine different types of irreducible fourth-order optical cones obtained by sequential bifurcations of eight main singular cones are established. The classification is based on the concept of roughness of systems depending on parameters.

  3. Study on optical weak absorption of borate crystals

    NASA Astrophysics Data System (ADS)

    Li, Xiaomao; Hu, Zhanggui; Yue, Yinchao; Yu, Xuesong; Lin, Zheshuai; Zhang, Guochun

    2013-10-01

    Borate crystal is an important type of nonlinear optical crystals used in frequency conversion in all-solid-state lasers. Especially, LiB3O5 (LBO), CsB3O5 (CBO) and CsLiB6O10 (CLBO) are the most advanced. Although these borate crystals are all constructed by the same anionic group-(B3O7)5-, they show different nonlinear optical properties. In this study, bulk weak absorption values of three borate crystals have been studied at 1064 nm by a photothermal common-path interferometer. The bulk weak absorption values of them along [1 0 0], [0 1 0] and [0 0 1] directions were obtained, respectively, to be approximately 17.5 ppm cm-1, 15 ppm cm-1 and 20 ppm cm-1 (LBO); 80 ppm cm-1, 100 ppm cm-1 and 40 ppm cm-1 (CBO); 600 ppm cm-1, 600 ppm cm-1 and 150 ppm cm-1 (CLBO) at 1064 nm. The results showed an obvious discrepancy of the values of these crystals along three axis directions. A correlation between the bulk weak absorption property and crystal intrinsic structure was then discussed. It is found that the bulk weak absorption values strongly depend on the interstitial area surrounded by the B-O frames. The interstitial area is larger, the bulk weak absorption value is higher.

  4. Optical trapping of the anisotropic crystal nanorod.

    PubMed

    Bareil, Paul B; Sheng, Yunlong

    2015-05-18

    We observed in the optical tweezers experiment that some anisotropic nanorod was stably trapped in an orientation tiled to the beam axis. We explain this trapping with the T-matrix calculation. As the vector spherical wave functions do not individually satisfy the anisotropic vector wave equation, we expand the incident and scattered fields in the isotropic buffer in terms of E→, and the internal field in the anisotropic nanoparticle in terms of D→, and use the boundary condition for the normal components of D→ to compute the T-matrix. We found that when the optical axes of an anisotropic nanorod are not aligned to the nanorod axis, the nanorod may be trapped stably at a tilted angle, under which the lateral torque equals to zero and the derivative of the torque is negative. PMID:26074566

  5. PEG Functionalization of Whispering Gallery Mode Optical Microresonator Biosensors to Minimize Non-Specific Adsorption during Targeted, Label-Free Sensing.

    PubMed

    Wang, Fanyongjing; Anderson, Mark; Bernards, Matthew T; Hunt, Heather K

    2015-01-01

    Whispering Gallery Mode (WGM) optical microresonator biosensors are a powerful tool for targeted detection of analytes at extremely low concentrations. However, in complex environments, non-specific adsorption can significantly reduce their signal to noise ratio, limiting their accuracy. To overcome this, poly(ethylene glycol) (PEG) can be employed in conjunction with appropriate recognition elements to create a nonfouling surface capable of detecting targeted analytes. This paper investigates a general route for the addition of nonfouling elements to WGM optical biosensors to reduce non-specific adsorption, while also retaining high sensitivity. We use the avidin-biotin analyte-recognition element system, in conjunction with PEG nonfouling elements, as a proof-of-concept, and explore the extent of non-specific adsorption of lysozyme and fibrinogen at multiple concentrations, as well as the ability to detect avidin in a concentration-dependent fashion. Ellipsometry, contact angle measurement, fluorescence microscopy, and optical resonator characterization methods were used to study non-specific adsorption, the quality of the functionalized surface, and the biosensor's performance. Using a recognition element ratio to nonfouling element ratio of 1:1, we showed that non-specific adsorption could be significantly reduced over the controls, and that high sensitivity could be maintained. Due to the frequent use of biotin-avidin-biotin sandwich complexes in functionalizing sensor surfaces with biotin-labeled recognition elements, this chemistry could provide a common basis for creating a non-fouling surface capable of targeted detection. This should improve the ability of WGM optical biosensors to operate in complex environments, extending their application towards real-world detection. PMID:26213937

  6. Ionic and electronic processes in non-linear optical crystals

    NASA Astrophysics Data System (ADS)

    Ogorodnikov, Igor N.; Yakovlev, Victor Yu.

    2005-01-01

    The paper presents the results of a study of the formation and decay of lattice defects in nonlinear optical crystals of NH4H2PO4 (ADP), KH2PO4 (KDP), Li2B4O7 (LTB) and LiB3O5 (LBO) with a sublattice of mobile hydrogen (ADP, KDP) and lithium (LTB, LBO) cations. By means of the luminescent and absorption optical spectroscopy with (the) a nanosecond time resolution under excitation with an electron beam, it was revealed that the optical absorption of these crystals in the visible and UV spectral ranges is produced by optical hole-transitions from the local defect level to the valence band states. The valence band density of the states determines the optical absorption spectral profile, and the relaxation kinetics is rated by the interdefect radiationless tunnel recombination between the trapped hole center and the H0 and Li0 electron trapped centers. At 290 K, the H0 and Li0 centers are subject to thermally stimulated migration. All manifestations of a radiative recombination observed in these crystals are accounted for by the involvement of additional electronic and hole centers of a different nature in the recombination process.

  7. Optical diode made from a moving photonic crystal.

    PubMed

    Wang, Da-Wei; Zhou, Hai-Tao; Guo, Miao-Jun; Zhang, Jun-Xiang; Evers, Jörg; Zhu, Shi-Yao

    2013-03-01

    Optical diodes controlling the flow of light are of principal significance for optical information processing. They transmit light from an input to an output, but not in the reverse direction. This breaking of time reversal symmetry is conventionally achieved via Faraday or nonlinear effects. For applications in a quantum network, features such as the abilities of all-optical control, on-chip integration, and single-photon operation are important. Here we propose an all-optical optical diode which requires neither magnetic fields nor strong input fields. It is based on a "moving" photonic crystal generated in a three-level electromagnetically induced transparency medium in which the refractive index of a weak probe is modulated by the moving periodic intensity of a strong standing coupling field with two detuned counterpropagating components. Because of the Doppler effect, the frequency range of the crystal's band gap for the probe copropagating with the moving crystal is shifted from that for the counterpropagating probe. This mechanism is experimentally demonstrated in a room temperature Cs vapor cell. PMID:23496710

  8. Sensors and Biosensors for the Determination of Small Molecule Biological Toxins

    PubMed Central

    Wang, Xiang-Hong; Wang, Shuo

    2008-01-01

    The following review of sensors and biosensors focuses on the determination of commonly studied small molecule biological toxins, including mycotoxins and small molecule neurotoxins. Because of the high toxicity of small molecule toxins, an effective analysis technique for determining their toxicity is indispensable. Sensors and biosensors have emerged as sensitive and rapid techniques for toxicity analysis in the past decade. Several different sensors for the determination of mycotoxins and other small molecule neurotoxins have been reported in the literature, and many of these sensors such as tissue biosensors, enzyme sensors, optical immunosensors, electrochemical sensors, quartz crystal sensors, and surface plasmon resonance biosensors are reviewed in this paper. Sensors are a practical and convenient monitoring tool in the area of routine analysis, and their specificity, sensitivity, reproducibility and analysis stability should all be improved in future work. In addition, accuracy field portable sensing devices and multiplexing analysis devices will be important requirement for the future.

  9. Ultrabroadband noncollinear optical parametric amplification with LBO crystal.

    PubMed

    Zhao, Baozhen; Jiang, Yongliang; Sueda, Keiich; Miyanaga, Noriaki; Kobayashi, Takayoshi

    2008-11-10

    Ultrabroadband visible noncollinear optical parametric amplification (NOPA) was achieved in an LBO crystal, with a continuum seed pulse generated from a sapphire plate. The spectral bandwidth of the amplified visible pulse was about 200 nm, which can support sub-5 fs pulse amplification. An amplified output of 0.21 microJ with an average gain of about 210 was achieved. This provides, to the best of our knowledge, the first-time demonstration of such broadband amplification with a biaxial nonlinear optical crystal. Both the simulation and experimental results indicate that the LBO has a great potential as nonlinear medium in power amplifier for TW to PW noncollinear optical parametric chirped pulse amplification (NOPCPA) systems. PMID:19581976

  10. Piezoelectric resonance calorimetry of nonlinear-optical crystals under laser irradiation

    NASA Astrophysics Data System (ADS)

    Ryabushkin, Oleg A.; Konyashkin, Aleksey V.; Myasnikov, Daniil V.; Tyrtyshnyy, Valentin A.; Vershinin, Oleg I.

    2013-09-01

    Novel method is proposed for determination of nonlinear-optical crystal both heat transfer and optical absorption coefficients by measuring kinetics of the laser-irradiated crystal temperature-dependent piezoelectric resonance frequency. When laser radiation propagates through the crystal its temperature evaluation with time is directly determined from crystal piezoelectric resonance frequency shift, which is precisely measured by analyzing crystal response to the applied ac electric voltage. Heat transfer and optical absorption coefficients are obtained using measured characteristic time of crystal laser heating kinetics by solving nonstationary heat conduction equation. Experiments were performed with nonlinear-optical α-quartz, lithium triborate (LBO) and periodically poled lithium niobate (PPLN) crystals.

  11. Biosensor utilizing a liquid crystal/water interface functionalized with poly(4-cyanobiphenyl-4'-oxyundecylacrylate-b-((2-dimethyl amino) ethyl methacrylate)).

    PubMed

    Omer, Muhammad; Khan, Mashooq; Kim, Young Kyoo; Lee, Joon Hyung; Kang, Inn-Kyu; Park, Soo-Young

    2014-09-01

    TEMPDMAEMA grid cell. DNA, a pH-independent strong anionic polyelectrolyte, was also tested with the TEMPDMAEMA grid cell, and it exhibited an H-P transformation at the charged state of PDMAEMA below its pKa threshold at concentrations higher than 0.01wt%. Thus, we demonstrated that the TEMPDMAEMA grid cell effectively facilitated the detection of negatively charged biomaterials (i.e.; protein and DNA) through the H-P transformation using the polarized optical microscope. This simple and inexpensive experimental set-up for non-specific biomaterial detection lays the basic groundwork for developing effective biosensors using polyelectrolytes. PMID:25009103

  12. Topographical studies on GNF crystals of non linear optical origin

    NASA Astrophysics Data System (ADS)

    Khandpekar, M. M.; Pati, S. P.

    2013-02-01

    α-glycine has been combined with equal amount of nitric acid and hydrofluoric acid to form GNF crystals. Transparent and elongated crystals of appreciable sizes (2.5 cm length) useful for dislocation studies have been obtained from solution by slow evaporation in 3-4 weeks time. Crystals were found to be delicate and care is needed while handling them. The external geometry of the crystals was found to vary with composition. Glacial acetic acid (GAA) is found to be universal etching agent. GAA produces well defined elongated etch pits on the habit faces and curved triangular pits on cleavage faces in 15 seconds time. Evidence of impurity inclusions and pits on these inclusions have been detected. The orientation of pits on partial cleavage faces are clearly seen to differ. Occasional presence of long domain lines crossing the field of view has been observed. The curvature of pits edges indicates an optically active material with lower symmetry.

  13. Complementary interference method for determining optical parameters of liquid crystals

    NASA Astrophysics Data System (ADS)

    Kowiorski, K.; Kędzierski, J.; Raszewski, Z.; Kojdecki, M. A.; Chojnowska, O.; Garbat, K.; Miszczyk, E.; Piecek, W.

    2016-04-01

    Wedge cells of small apex angle, filled with liquid crystals, were used to determining optical characteristics as functions of temperature for three liquid crystalline mixtures recently produced and a reference nematic. The interference fringes appearing in polarised monochromatic light (of sodium yellow line) normally incident on the cell were exploited to measure the ordinary and extraordinary refractive indices in the reflection mode and birefringence in the transmission mode. The measurements were repeated using Abbe's refractometer for 6CHBT as the reference to verifying the precision. Additionally the order parameter was computed from birefringence as a function of temperature. The results confirm the usefulness of the method and provide the properties of two nematic liquid crystals of small and large birefringence and one smectic liquid crystal of medium birefringence, recently produced. The experimental systems served also to investigating phase transition between the liquid crystals and the isotropic liquid at near-clearing temperature.

  14. Dislocations, microhardness and optical studies on glycine potassium nitrate crystal

    NASA Astrophysics Data System (ADS)

    Chandra, Ch. Sateesh; Nagaraju, D.; Shekar, P. V. Raja; Rao, T. Tirumal; Krishna, N. Gopi

    2015-06-01

    Single crystals of glycine potassium nitrate (GPN), a semiorganic nonlinear optical crystal, of dimensions 15×12×4 mm3 were grown in a period of 10 days. The defect content present in the crystals was estimated by chemical etching technique. The results indicate that the average dislocation density is about 4.1×103/cm2. The UV-Vis. studies indicate that the crystal has a wide transmission range. The Kurtz powder test indicates that the second harmonic generation efficiency of GPN is 2.5 times that of KDP. The load-hardness curves for GPN were studied over the load range 10-100 g. The anisotropy in hardness was studied using Knoop indentation technique.

  15. Silicon dioxide nanoporous structure with liquid crystal for optical sensors

    NASA Astrophysics Data System (ADS)

    Sushynskyi, Orest; Vistak, Maria; Gotra, Zenon; Fechan, Andriy; Mikityuk, Zinoviy

    2013-05-01

    It has been studied the spectral characteristics of the porous silicon dioxide and cholesteric liquid crystal. It has been shown that doping of the EE1 cholesteric liquid crystal with Fe3O4 magnetite nanoparticles doesn't shift significantly the position of the transmittance minimum of the material. It has been found that the deformation of chiral pitch of cholesteric liquid crystal with magnetite is observed in case of doping of porous nanocomposite host with following shifting of minimum of transmittance into short wavelength direction. It has been shown that influence of carbon monoxide on optical characteristics of the cholesteric liquid crystal with magnetite can be explained by the interaction of CARBON MONOXIDE molecules with magnetite nanodopants.

  16. Hydrothermal crystal growth of oxides for optical applications

    NASA Astrophysics Data System (ADS)

    McMillen, Colin David

    2007-12-01

    The manipulation of light has proven to be an integral part of today's technology-based society. In particular, there is great interest in obtaining coherent radiation in all regions of the optical spectrum to advance technology in military, medical, industrial, scientific and consumer fields. Exploring new crystal growth techniques as well as the growth of new optical materials is critical in the advancement of solid state optics. Surprisingly, the academic world devotes little attention to the growth of large crystals. This shortcoming has left gaps in the optical spectrum inaccessible by solid state devices. This dissertation explores the hydrothermal crystal growth of materials that could fill two such gaps. The first gap exists in the deep-UV region, particularly below 200 nm. Some materials such as LiB3O5 and beta-BaB2O4 can generate coherent light at wavelengths as low as 205 nm. The growth of these materials was explored to investigate the feasibility of the hydrothermal method as a new technique for growing these crystals. Particular attention was paid to the descriptive chemistry surrounding these systems, and several novel structures were elucidated. The study was also extended to the growth of materials that could be used for the generation of coherent light as low as 155 nm. Novel synthetic schemes for Sr2Be2B2O7 and KBe2BO 3F2 were developed and the growth of large crystals was explored. An extensive study of the structures, properties and crystal growth of related compounds, RbBe2BO3F2 and CsBe2BO 3F2, was also undertaken. Optimization of a number of parameters within this family of compounds led to the hydrothermal growth of large, high quality single crystal at rates suitable for large-scale growth. The second gap in technology is in the area of high average power solid state lasers emitting in the 1 mum and eye-safe (>1.5 mum) regions. A hydrothermal technique was developed to grow high quality crystals of Sc 2O3 and Sc2O3 doped with suitable

  17. Electro-optical field sensor using single total internal reflection in electro-optical crystals

    NASA Astrophysics Data System (ADS)

    Kijima, K.; Abe, O.; Shimizu, A.; Nakamura, T.; Kono, H.; Hagihara, S.; Torikai, E.; Hori, H.

    2015-08-01

    A novel electro-optical radio frequency field sensor with simple structure and high sensitivity is realized using single total internal reflection in electro-optical crystals. Without employing any waveguide structures, the minimum detectable electric field strength of the total internal reflection electro-optical-sensor is estimated to 86.52 dB μV/m (21.18 mV/m) at a resolution band width of 100 Hz for a short interaction length.

  18. Growth of bulk single crystals of organic materials for nonlinear optical devices - An overview

    NASA Technical Reports Server (NTRS)

    Penn, Benjamin G.; Cardelino, Beatriz H.; Moore, Craig E.; Shields, Angela W.; Frazier, D. O.

    1991-01-01

    Highly perfect single crystals of nonlinear optical organic materials are required for use in optical devices. An overview of the bulk crystal growth of these materials by melt, vapor, and solution processes is presented. Additionally, methods that may be used to purify starting materials, detect impurities at low levels, screen materials for crystal growth, and process grown crystals are discussed.

  19. Organic silicone sol-gel polymer as a noncovalent carrier of receptor proteins for label-free optical biosensor application.

    PubMed

    Ren, Jun; Wang, Linghua; Han, Xiuyou; Cheng, Jianfang; Lv, Huanlin; Wang, Jinyan; Jian, Xigao; Zhao, Mingshan; Jia, Lingyun

    2013-01-23

    Optical biosensing techniques have become of key importance for label-free monitoring of biomolecular interactions in the current proteomics era. Together with an increasing emphasis on high-throughput applications in functional proteomics and drug discovery, there has been demand for facile and generally applicable methods for the immobilization of a wide range of receptor proteins. Here, we developed a polymer platform for microring resonator biosensors, which allows the immobilization of receptor proteins on the surface of waveguide directly without any additional modification. A sol-gel process based on a mixture of three precursors was employed to prepare a liquid hybrid polysiloxane, which was photopatternable for the photocuring process and UV imprint. Waveguide films were prepared on silicon substrates by spin coating and characterized by atomic force microscopy for roughness, and protein adsorption. The results showed that the surface of the polymer film was smooth (rms = 0.658 nm), and exhibited a moderate hydrophobicity with the water contact angle of 97°. Such a hydrophobic extent could provide a necessary binding strength for stable immobilization of proteins on the material surface in various sensing conditions. Biological activity of the immobilized Staphylococcal protein A and its corresponding biosensing performance were demonstrated by its specific recognition of human Immunoglobulin G. This study showed the potential of preparing dense, homogeneous, specific, and stable biosensing surfaces by immobilizing receptor proteins on polymer-based optical devices through the direct physical adsorption method. We expect that such polymer waveguide could be of special interest in developing low-cost and robust optical biosensing platform for multidimensional arrays. PMID:23259485

  20. A Flexible Parameterization for Shortwave Optical Properties of Ice Crystals

    NASA Technical Reports Server (NTRS)

    VanDiedenhoven, Bastiaan; Ackerman, Andrew S.; Cairns, Brian; Fridlind, Ann M.

    2014-01-01

    A parameterization is presented that provides extinction cross section sigma (sub e), single-scattering albedo omega, and asymmetry parameter (g) of ice crystals for any combination of volume, projected area, aspect ratio, and crystal distortion at any wavelength in the shortwave. Similar to previous parameterizations, the scheme makes use of geometric optics approximations and the observation that optical properties of complex, aggregated ice crystals can be well approximated by those of single hexagonal crystals with varying size, aspect ratio, and distortion levels. In the standard geometric optics implementation used here, sigma (sub e) is always twice the particle projected area. It is shown that omega is largely determined by the newly defined absorption size parameter and the particle aspect ratio. These dependences are parameterized using a combination of exponential, lognormal, and polynomial functions. The variation of (g) with aspect ratio and crystal distortion is parameterized for one reference wavelength using a combination of several polynomials. The dependences of g on refractive index and omega are investigated and factors are determined to scale the parameterized (g) to provide values appropriate for other wavelengths. The parameterization scheme consists of only 88 coefficients. The scheme is tested for a large variety of hexagonal crystals in several wavelength bands from 0.2 to 4 micron, revealing absolute differences with reference calculations of omega and (g) that are both generally below 0.015. Over a large variety of cloud conditions, the resulting root-mean-squared differences with reference calculations of cloud reflectance, transmittance, and absorptance are 1.4%, 1.1%, and 3.4%, respectively. Some practical applications of the parameterization in atmospheric models are highlighted.

  1. Single crystal x-ray diffraction: optical and micro hardness studies on chalcone derivative single crystal

    NASA Astrophysics Data System (ADS)

    Crasta, Vincent; Ravindrachary, V.; Bhajantri, R. F.; Naveen, S.; Shridar, M. A.; Shashidhara Prasad, J.

    2005-08-01

    1-(4-methylphenyl)-3-(4- N, N dimethyl amino phenyl)-2-propen-1-one, a chalcone derivative nonlinear optical material has been synthesized by standard method. FT-IR and NMR spectral studies have been performed to confirm the molecular structure of the synthesized compound. The single crystals up to a dimension of 13 x 9 x 3 mm3 were grown by slow evaporation method. The grown crystals were transparent in the entire visible region and absorbs in the UV-region. The refractive index has been measured using a He-Ne laser. The grown crystals have been subjected to single crystal X-ray diffraction studies to determine the crystal structure and hence the cell parameters of the crystal. From this study it is found that this compound crystallizes in orthorhombic system with a space group P212121 and corresponding lattice parameters are, a = 7.3610(13) Å, b = 11.651(2) Å, c = 17.6490(17) Å. The Kurtz powder second harmonic generation test shows that the compound is a potential candidate for Photonic application. The micro hardness test on these crystals were carried out and the load dependence hardness was observed

  2. An optical biosensor assay for rapid dual detection of Botulinum neurotoxins A and E

    PubMed Central

    Lévêque, Christian; Ferracci, Géraldine; Maulet, Yves; Mazuet, Christelle; Popoff, Michel R.; Blanchard, Marie-Pierre; Seagar, Michael; El Far, Oussama

    2015-01-01

    The enzymatic activity of the pathogenic botulinum neurotoxins type A and E (BoNT/A and E) leads to potentially lethal paralytic symptoms in humans and their prompt detection is of crucial importance. A chip assay based on Surface Plasmon Resonance monitoring of the cleavage products is a simple method that we have previously established to detect BoNT/A activity. We have now developed a similar format assay to measure BoNT/E activity. A monoclonal antibody specifically recognizing SNAP25 cleaved by BoNT/E was generated and used to measure the appearance of the neo-epitope following injection of BoNT/E over SNAP-25 immobilized on a chip. This assay detects BoNT/E activity at 1 LD50/ml within minutes and linear dose-responses curves were obtained using a multiplexed biosensor. A threshold of 0.01 LD50/ml was achieved after 5 h of cleavage. This assay is 10-fold more sensitive than the in vivo assay for direct detection of BoNT/E in serum samples. The SNAP25 chip assay is able to discriminate in an automated manner the presence of BoNT/E, BoNT/A or a combination of both toxins. PMID:26648139

  3. Preliminary study of simultaneous multi-anticoagulant deficiency diagnosis by fiber optic multi-analyte biosensor.

    PubMed

    Tang, Liang; Kang, Kyung A

    2005-01-01

    Protein C (PC), protein S (PS), antithrombin III, and plasminogen are four important anticoagulants in blood plasma. Deficiency of any of these biomolecules may lead to thrombo-embolic complications including lung embolism, heart attack, and stroke. A multi-factor sensing system is beneficial for identifying the cause of abnormal blood clotting more effectively, rapidly, and cost-effectively. As an initial effort toward simultaneous multi-anticoagulant detection, a PC and PS dual-sensing system has been under development in our research group. A fiberoptic PC biosensor utilizing fluorophore-mediated sandwich immunoassay was already developed for rapid (-5 minutes) PC deficiency diagnosis. After a single PS sensor was developed for the PS deficiency diagnosis, the two sensors were connected in series to form a dual-sensing system. The cross-reactivity between the analytes and the sensors was found to be minimal. For easier sensing operation, a mixture of fluorophore-linked anti-PC and anti-PS was applied. The results showed that the mixture can be used with a slight signal reduction. When PC and PS was mixed in a sample, the signal intensity was decreased by approximately 5% for both sensors. A study is currently being performed to overcome the signal reduction by increasing the flow velocity and incubation time. PMID:16594166

  4. Nonlinear optical processes in liquid crystals and applications in optical switching

    NASA Astrophysics Data System (ADS)

    Zhao, Shuo

    This dissertation research completes the exploration and development of the theoretical framework for collective liquid crystalline optical nonlinearities capable of response speeds in the microseconds---nanoseconds scale, which is more than 1000 times faster than the conventional liquid crystal (LC) response speed. Also explored in this dissertation are utilizations of these new discoveries to achieve all-optical switching. This work demonstrates all-optical switching using nonlinear orientational and thermal effects, respectively, in pure and dye-doped twisted nematic liquid crystal (TNLC) cells set between crossed polarizers. In the former case, the flow of liquid crystal molecules is generated by Maxwell stress and thereby exerts a torque on the liquid crystal. The resulting reorientation changes the effective birefringence of the liquid crystal, affecting the overall transmission. In dye-doped twisted nematics, the absorption of dye enhances laser heating in the liquid crystal, which leads to reduction of the order parameter and the corresponding macroscopic birefringence, finally making the transmission drop to zero. Following the sequences of these processes, detailed modeling for collective responses of liquid crystal and the time evolution of transmissions under short laser pulses are presented. Besides theoretical description and modeling, we demonstrate the nonlinear optical switching experimentally. The switching threshold and time are consistent with the simulation results. While dye-doped liquid crystals have a low threshold for nonlinear switching, pure twisted nematics possess high transparency in the entire visible and nearinfrared spectrum. These findings are believed to advance the current arsenal of highperformance materials for integration/use in advanced optical systems designed for sensor protection; laser hardening; and other beam/image switching, sensing, and processing operations.

  5. Thermo-optical effects and fiber optic sensing device based on polymer dispersed liquid crystals

    NASA Astrophysics Data System (ADS)

    Sirleto, Luigi; Righini, Giancarlo C.; Ciaccheri, Leonardo; Rish, Mahmoud A.; Simoni, Francesco F.

    2001-05-01

    In this paper an experimental study of thermo-optical properties of polymer dispersed liquid crystals (PDLC), prepared by PIPS in bulk and in confined cylindrical geometry, is presented. The transmissivity of PDLC In bulk as a function of temperature proves the existence of temperature optical switching. We have also demonstrated the existence of optical bistability, which could be interesting in develop of logical optical devices as optical memory elements. A bistable al fiber optic sensors based on PDLC is also presented. In this device PDLC permits at the same time the optomechanical interconnection of tow fibers and the modulation of the light crossing the device. As the modulation can be controlled by external temperature, the device has been proved to be suitable for the realization of a heat flow sensor. Without any optimization of the device we have obtained an ON-OFF contrast of 8 dB and a response time comparable with other conventional device using nematic LCs. This sensor is compact, rugged and is cheap, because it does not require a complex fabrication and alignment technology. It presents the typical advantages of both the fiber optic sensor and the liquid crystal technology. We note that its main advantage is a small thermal capacity, which is comparable with electronic device as thermistors, and it represents a significant improvement for the sensor based on liquid crystals. Further theoretical studies are necessary in order to understand in depth it thermo-optical characteristics.

  6. Liquid-Crystal Biosensor Based on Nickel-Nanosphere-Induced Homeotropic Alignment for the Amplified Detection of Thrombin.

    PubMed

    Zhao, Dongyu; Peng, Yi; Xu, Lihong; Zhou, Wei; Wang, Qian; Guo, Lin

    2015-10-28

    A new liquid-crystal (LC)-based sensor operated by nickel nanosphere (NiNS)-induced homeotropic alignment for the label-free monitoring of thrombin was reported. When doped with NiNSs, a uniform vertical orientation of 4-cyano-4'-pentylbiphenyl (5CB) was easily obtained. A sandwich system of aptamer/thrombin/aptamer-functionalized gold nanoparticles (AuNPs) was fabricated, and AuNPs-aptamer conjugation caused the disruption of the 5CB orientation, leading to an obvious change of the optical appearance from a dark to a bright response to thrombin concentrations from 0.1 to 100 nM. This design also allowed quantitative detection of the thrombin concentration. This distinctive and sensitive thrombin LC sensor provides a new principle for building LC-sensing systems. PMID:26458050

  7. Silicon single-crystal cryogenic optical resonator.

    PubMed

    Wiens, Eugen; Chen, Qun-Feng; Ernsting, Ingo; Luckmann, Heiko; Rosowski, Ulrich; Nevsky, Alexander; Schiller, Stephan

    2014-06-01

    We report on the demonstration and characterization of a silicon optical resonator for laser frequency stabilization, operating in the deep cryogenic regime at temperatures as low as 1.5 K. Robust operation was achieved, with absolute frequency drift less than 20 Hz over 1 h. This stability allowed sensitive measurements of the resonator thermal expansion coefficient (α). We found that α=4.6×10(-13)  K(-1) at 1.6 K. At 16.8 K α vanishes, with a derivative equal to -6×10(-10)  K(-2). The temperature of the resonator was stabilized to a level below 10 μK for averaging times longer than 20 s. The sensitivity of the resonator frequency to a variation of the laser power was also studied. The corresponding sensitivities and the expected Brownian noise indicate that this system should enable frequency stabilization of lasers at the low-10(-17) level. PMID:24876023

  8. Tubular optical waveguide particle plasmon resonance biosensor for multiplex real-time and label-free detection

    NASA Astrophysics Data System (ADS)

    Huang, Chen-Han; Lin, Hsing-Ying; Chau, Lai-Kwan

    2013-05-01

    A tubular optical waveguide particle plasmon resonance (TW-PPR) sensor is demonstrated for higher-throughput and sensitive label-free biochemical detections. Compared to other evanescent field absorption sensors, the TW-PPR sensor possesses merits of itself being a microchamber of a defined sample volume, a mechanical support for sensor coatings, and ease of systematic multichannel expansion. The sensor resolution is estimated to be 2.6 × 10-6 RIU in measuring solutions of various refractive indices (RIs). Additionally, the multichannel TW-PPR sensing system can perform independent measurements simultaneously and its limit of detection (LOD) of anti-DNP antibody and streptavidin separately measured by DNP-functionalized and biotin-functionalized TW-PPR microchambers is demonstrated to be 1.21 × 10-10 and 2.27 × 10-10 g/ml, respectively. Accurate determinations of these molecules with known concentrations spiked in artificial urine are examined and the sensor responses give excellent correlation with results demonstrated in standard buffer examinations, supporting the utility of the device for analyte screening in more complex media. The TWPPR sensor can be inexpensively fabricated and has a special niche as high-sensitivity refractive index sensor as well as biosensor for label-free monitoring biomolecular interactions in real-time. It is ideally suitable for disposable uses, especially promising for convenient higher-throughput biochemical sensing applications.

  9. Development of combination tapered fiber-optic biosensor dip probe for quantitative estimation of interleukin-6 in serum samples

    NASA Astrophysics Data System (ADS)

    Wang, Chun Wei; Manne, Upender; Reddy, Vishnu B.; Oelschlager, Denise K.; Katkoori, Venkat R.; Grizzle, William E.; Kapoor, Rakesh

    2010-11-01

    A combination tapered fiber-optic biosensor (CTFOB) dip probe for rapid and cost-effective quantification of proteins in serum samples has been developed. This device relies on diode laser excitation and a charged-coupled device spectrometer and functions on a technique of sandwich immunoassay. As a proof of principle, this technique was applied in a quantitative estimation of interleukin IL-6. The probes detected IL-6 at picomolar levels in serum samples obtained from a patient with lupus, an autoimmune disease, and a patient with lymphoma. The estimated concentration of IL-6 in the lupus sample was 5.9 +/- 0.6 pM, and in the lymphoma sample, it was below the detection limit. These concentrations were verified by a procedure involving bead-based xMAP technology. A similar trend in the concentrations was observed. The specificity of the CTFOB dip probes was assessed by analysis with receiver operating characteristics. This analysis suggests that the dip probes can detect 5-pM or higher concentration of IL-6 in these samples with specificities of 100%. The results provide information for guiding further studies in the utilization of these probes to quantify other analytes in body fluids with high specificity and sensitivity.

  10. Photonic crystal-based RGB primary colour optical filter

    NASA Astrophysics Data System (ADS)

    Singh, Brahm Raj; Rawal, Swati; Sinha, R. K.

    2016-08-01

    We have presented an RGB optical filter, based on photonic crystal (PhC) waveguides, with the hexagonal arrangement of GaP rods in air. It filters out the three primary colours of the visible range, red (R, λ = 648 nm), green (G, λ = 540 nm) and blue (B, λ = 470 nm). The plane wave expansion method is applied for estimating the dispersion curves and finite element method is utilized in examining the propagation characteristics of the designed PhC-based optical filter. Transmittance, extinction ratio and tolerance analysis have further been calculated to confirm the performance of the proposed optical filter to work in the visible range of optical spectrum and filter out the three primary colours (red, green, blue) along different output ports.

  11. Nonlinear Optics and Solitons in Photonic Crystal Fibres

    NASA Astrophysics Data System (ADS)

    Skryabin, Dmitry V.; Wadsworth, William J.

    The fibre optics revolution in communication technologies followed the 1950's demonstration of the glass fibres with dielectric cladding [1]. Transmission applications of fibre optics have become a dominant modern day technology not least because nonlinearities present in - or introduced into - glass and enhanced by the tight focusing of the fibre modes allow for numerous light processing techniques, such as amplification, frequency conversion, pulse shaping, and many others. For these reasons, and because of the rich fundamental physics behind it, nonlinear fibre optics has become a blossoming discipline in its own right [1]. The 1990's witnessed another important development in fibre optics. Once again it came from a new approach to the fibre cladding, comprising a periodic pattern of air holes separated by glass membranes forming a photonic crystal structure [2, 3]. This prompted the name Photonic Crystal Fibres (PCFs). The fascinating story behind the invention of PCF and research into various fibre designs can be found, e.g., in [4]. Our aim here is to review the role played by PCFs in nonlinear and quantum optics, which is becoming the mainstream of the PCF related research and applications. Our focus will be on the areas where PCFs have brought to life effects and applications which were previously difficult, impossible to observe or simply not thought about.

  12. Extreme optical confinement in a slotted photonic crystal waveguide

    SciTech Connect

    Caër, Charles; Le Roux, Xavier; Cassan, Eric; Combrié, Sylvain De Rossi, Alfredo

    2014-09-22

    Using Optical Coherence Tomography, we measure the attenuation of slow light modes in slotted photonic crystal waveguides. When the group index is close to 20, the attenuation is below 300 dB cm{sup −1}. Here, the optical confinement in the empty slot is very strong, corresponding to an ultra-small effective cross section of 0.02 μm{sup 2}. This is nearly 10 times below the diffraction limit at λ = 1.5 μm, and it enables an effective interaction with a very small volume of functionalized matter.

  13. Nanosecond Electro-Optic Switching of a Liquid Crystal

    NASA Astrophysics Data System (ADS)

    Borshch, Volodymyr; Shiyanovskii, Sergij V.; Lavrentovich, Oleg D.

    2013-09-01

    Electrically induced reorientation of nematic liquid crystal (NLC) molecules caused by dielectric anisotropy of the material is a fundamental phenomenon widely used in modern technologies. Its Achilles heel is a slow (millisecond) relaxation from the field-on to the field-off state. We present an electro-optic effect in an NLC with a response time of about 30 ns to both the field-on and field-off switching. This effect is caused by the electric field induced modification of the order parameters and does not require reorientation of the optic axis (director).

  14. Optical modulator based on GaAs photonic crystals

    NASA Astrophysics Data System (ADS)

    Li, Jiusheng

    2005-11-01

    In this letter, we propose a novel optical modulator based on GaAs photonic crystals and investigate its optically properties numerically by using the finite-difference time-domain method. The position of the cutoff frequency can be varied by free carriers injection, and the band gap shift can be observed. Band gap shift is used to modulate light. Bing several micrometers length, low insertion loss, and large extinction ratios, the modulator can be used in ultra-small and ultra-dense photonic integrated circuits.

  15. Eliminating crystals in non-oxide optical fiber preforms and optical fibers

    NASA Technical Reports Server (NTRS)

    LaPointe, Michael R. (Inventor); Tucker, Dennis S. (Inventor)

    2010-01-01

    A method is provided for eliminating crystals in non-oxide optical fiber preforms as well as optical fibers drawn therefrom. The optical-fiber-drawing axis of the preform is aligned with the force of gravity. A magnetic field is applied to the preform as it is heated to at least a melting temperature thereof. The magnetic field is applied in a direction that is parallel to the preform's optical-fiber-drawing axis. The preform is then cooled to a temperature that is less than a glass transition temperature of the preform while the preform is maintained in the magnetic field. When the processed preform is to have an optical fiber drawn therefrom, the preform's optical-fiber-drawing axis is again aligned with the force of gravity and a magnetic field is again applied along the axis as the optical fiber is drawn from the preform.

  16. Simulation of optical diagnostics for crystal growth: models and results

    NASA Astrophysics Data System (ADS)

    Banish, Michele R.; Clark, Rodney L.; Kathman, Alan D.; Lawson, Shelah M.

    1991-12-01

    A computer simulation of a two-color holographic interferometric (TCHI) optical system was performed using a physical (wave) optics model. This model accurately simulates propagation through time-varying, 2-D or 3-D concentration and temperature fields as a wave phenomenon. The model calculates wavefront deformations that can be used to generate fringe patterns. This simulation modeled a proposed TriGlycine sulphate TGS flight experiment by propagating through the simplified onion-like refractive index distribution of the growing crystal and calculating the recorded wavefront deformation. The phase of this wavefront was used to generate sample interferograms that map index of refraction variation. Two such fringe patterns, generated at different wavelengths, were used to extract the original temperature and concentration field characteristics within the growth chamber. This proves feasibility for this TCHI crystal growth diagnostic technique. This simulation provides feedback to the experimental design process.

  17. Optical Fluctuation of Texture in Nematic Liquid Crystal Droplets

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Jo; Back, Sang-In; Lev, Bohdan; Kim, Jong-Hyun

    2016-07-01

    We report the observation of texture of a nematic liquid crystal droplet using a high-speed camera mounted on a polarizing optical microscope. The dark crossed texture obtained by the polarizing optical microscope of a nematic liquid crystal droplet has texture wobbles, which are related to the director field fluctuation excited by thermal energy. We confirm relaxation and oscillation modes. An exact solution of the director fluctuation modes with one-constant approximation and an external electric field is proposed. The theoretical predictions of the relaxation time match with our experimental results when varying the temperature, droplet size, and electric field. Relaxation time was insensitive to the temperature, increased with radius of droplet and slightly decreased with electric field. Several oscillation modes, which have no specific trend, were also found. The external electric field freezes the oscillation modes.

  18. Crystallization, Optical and Chemical Properties of Fluoride Glasses

    NASA Technical Reports Server (NTRS)

    Doremus, R. H.

    1985-01-01

    Fluoride glasses have great promise as infrared optical components, especially fibers, because they are transparent to 8 micrometers and higher. In order to optimize properties, different glass compositions are needed. Some are hard to form in a container, and may possibly be formable in a containerless furnace. Understanding of crystallization with and without a container could lead to glasses with optimum properties. Chemical durability (attack by water) can limit or extend the applicability of fluoride glasses. Progress to date is given.

  19. Optical Study of Liquid Crystal Doped with Multiwalled Carbon Nanotube

    NASA Astrophysics Data System (ADS)

    Gharde, Rita A.; Thakare, Sangeeta Y.

    2014-11-01

    Liquid crystalline materials have been useful for display devices i.e watches, calculators, automobile dashboards, televisions, multi media projectors etc. as well as in electro tunable lasers, optical fibers and lenses. Carbon nanotube is chosen as the main experimental factor in this study as it has been observed that Carbon Nano Tube influence the existing properties of liquid crystal host and with the doping of CNT can enhance1 the properties of LC. The combination of carbon nanotube (CNT) and liquid crystal (LC) materials show considerable interest in the scientific community due to unique physical properties of CNT in liquid crystal. Dispersion of CNTs in LCs can provide us a cheap, simple, versatile and effective means of controlling nanotube orientation on macroscopic scale with no restrictions on nanotube type. LCs have the long range orientational order rendering them to be anisotropic phases. If CNTs can be well dispersed in LC matrix, they will align with their long axes along the LC director to minimize distortions of the LC director field and the free energy. In this paper, we doped liquid crystal (Cholesteryl Nonanoate) by a small amount of multiwall carbon nanotube 0.05% and 0.1% wt. We found that by adding carbon nanotube to liquid crystals the melting point of the mixture is decreased but TNI is increased. It has been also observed that with incereas in concentration of carbon nanotube into liquid crystal shows conciderable effect on LC. The prepared samples were characterized using various techniques to study structural, thermal and optical properties i.e PMS, FPSS, UV-Vis spectroscopy, FT-IR measurements, and DTA.

  20. Eliminating Crystals in Non-Oxide Optical Fiber Preforms and Optical Fibers

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis S.; LaPointe, Michael R.

    2012-01-01

    Non ]oxide fiber optics such as heavy metal fluoride and chalcogenide glasses are extensively used in infrared transmitting applications such as communication systems, chemical sensors, and laser fiber guides for cutting, welding and medical surgery. The addition of rare earths such as erbium, enable these materials to be used as fiber laser and amplifiers. Some of these glasses however are very susceptible to crystallization. Even small crystals can lead to light scatter and a high attenuation coefficient, limiting their usefulness. Previously two research teams found that microgravity suppressed crystallization in heavy metal fluoride glasses. Looking for a less expensive method to suppress crystallization, ground based research was performed utilizing an axial magnetic field. The experiments revealed identical results to those obtained via microgravity processing. This research then led to a patented process for eliminating crystals in optical fiber preforms and the resulting optical fibers. In this paper, the microgravity results will be reviewed as well as patents and papers relating to the use of magnetic fields in various material and glass processing applications. Finally our patent to eliminate crystals in non ]oxide glasses utilizing a magnetic field will be detailed.

  1. Theoretical modelling of one dimensional photonic crystal based optical demultiplexer

    NASA Astrophysics Data System (ADS)

    Sharma, Gaurav; Kumar, Sushil; Prasad, Surendra; Singh, Vivek

    2016-05-01

    An optical demultiplexer through one-dimensional Si-SiO2 photonic crystal structure in the presence of air cavity with a single crystal PMN-0.38PT material is presented. The transmittance of this structure is obtained using the transfer matrix method. The transmittance of this structure shows a sharp passband in the band gap region. It is observed that by introducing PMN-0.38PT layer in both sides of the air cavity, the existing band gap region of Si-SiO2 structure is slightly increased. Here, PMN-0.38PT material is working as a tunable element for passband. By applying some external potential on PMN-0.38PT crystal, the thickness of cavity layer can be tuned and the passband can be placed at any desired wavelength in the band gap region. Since the photonic band gap region contains a range of wavelengths which are not allowed to pass through the structure can be considered as a multiplex signal for the proposed demultiplexer. Therefore, any optical signal that lies in the band gap region of the structure can be separated into its components as a pass band. Hence, the proposed structure will work as an optical demultiplexer.

  2. Enhanced sandwich immunoassay using antibody-functionalized magnetic iron-oxide nanoparticles for extraction and detection of soluble transferrin receptor on a photonic crystal biosensor.

    PubMed

    Peterson, Ross D; Chen, Weili; Cunningham, Brian T; Andrade, Juan E

    2015-12-15

    Iron deficiency anemia (IDA) has detrimental effects on individuals and societies worldwide. A standard sandwich assay (SA) for the detection of soluble transferrin receptor (sTfR), a biomarker of IDA, on a photonic crystal (PC) biosensor was established, but it was susceptible to non-specific signals from complex matrixes. In this study, iron-oxide nanoparticles (fAb-IONs) were used as magnetic immuno-probes to bind sTfR and minimize non-specific signals, while enhancing detection on the PC biosensor. This inverse sandwich assay (IA) method completely bound sTfR with low variability (<4% RSD) in buffer and allowed for its accurate and precise detection in sera (Liquichek™ control sera) on the PC biosensor using two certified ELISAs as reference methods. A linear dose-response curve was elicited at the fAb-IONs concentration in which the theoretical binding ratio (sTfR:fAb-IONs) was calculated to be <1 on the IA. The LoDs for sTfR in the SA and IA were similar (P>0.05) at 14 and 21 μg/mL, respectively. The inherent imprecision of the IA and reference ELISAs was σ(δ)=0.45 µg/mL and the mean biases for Liquichek™ 1, 2 and 3 were 0.18, 0.19 and -0.04 µg/mL, respectively. Whereas the inherent imprecision of the SA and reference ELISAs was σ(δ)=0.52 µg/mL and the biases for Liquichek™ 1, 2 and 3 were 0.66, 0.14 and -0.67 µg/mL, respectively. Thus, unlike the SA, the IA method measures sTfR with the same bias as the reference ELISAs. Combined magnetic separation and detection of nutrition biomarkers on PC biosensors represents a facile method for their accurate and reliable quantification in complex matrixes. PMID:26232676

  3. Direct observation of crystal growth from solution using optical investigation of a growing crystal face

    NASA Technical Reports Server (NTRS)

    Lal, Ravindra

    1994-01-01

    The first technical report for the period 1 Jan. 1993 till 31 Dec. 1993 for the research entitled, 'Direct observation of crystal growth from solution using Optical Investigation of a growing crystal Face' is presented. The work on the project did not start till 1 June 1993 due to the non-availability of the required personnel. The progress of the work during the period 1 June 1993 till the end of 1993 is described. Significant progress was made for testing various optical diagnostic techniques for monitoring crystal solution. Some of the techniques that are being tested are: heterodyne detection technique, in which changes in phase are measured as a interferometric function of time/crystal growth; a conventional technique, in which a fringe brightness is measured as a function of crystal growth/time; and a Mach-Zehnder interferometric technique in which a fringe brightness is measured as a function of time to obtain information on concentration changes. During the second year it will be decided to incorporate the best interferometric technique along with the ellipsometric technique, to obtain real time in-situ growth rate measurements. A laboratory mock-up of the first two techniques were made and tested.

  4. Optical switch using electro-optic crystal with phase matching films

    NASA Astrophysics Data System (ADS)

    Shirasaki, M.; Takagi, N.; Obokata, T.

    1981-07-01

    An electro-optical switch for the 1.3 micron wavelength is demonstrated which uses a thin crystal plate of Bi12SiO20 with SiO2-Si:H-SiO2 phase matching films as the polarization converter. The switch has a drive voltage of 390 V and an extinction ratio of less than -20 dB. By reducing the crystal thickness from 100 to 50 microns, the drive voltage could be reduced by a factor of two; a further reduction could be obtained by optimizing the crystal orientation.

  5. Optical apparatus using liquid crystals for shaping the spatial intensity of optical beams having designated wavelengths

    DOEpatents

    Jacobs, Stephen D.; Cerqua, Kathleen A.

    1987-01-01

    The spatial intensity profile of an optical beam of designated wavelengths, such as a laser beam, is shaped (the beam is apodized) by means of cholesteric liquid crystals of opposite chirality disposed successively along the path of the beam. The crystals have curved surfaces, which may be defined by a lens which defines the thickness of the liquid crystal fluid gap in a liquid crystal cell, so as to vary the selective reflection of the designated wavelength across the aperture of the beam. In this way, a soft aperture is provided. By using tandem cell pairs having liquid crystals of opposite chirality, but of different pitch, and with lenses of different curvature, beams of different wavelengths which are projected colinearly along the path may be individually tailored in spatial intensity profile.

  6. Optical apparatus using liquid crystals for shaping the spatial intensity of optical beams having designated wavelengths

    DOEpatents

    Jacobs, S.D.; Cerqua, K.A.

    1987-07-14

    The spatial intensity profile of an optical beam of designated wavelengths, such as a laser beam, is shaped (the beam is apodized) by means of cholesteric liquid crystals of opposite chirality disposed successively along the path of the beam. The crystals have curved surfaces, which may be defined by a lens which defines the thickness of the liquid crystal fluid gap in a liquid crystal cell, so as to vary the selective reflection of the designated wavelength across the aperture of the beam. In this way, a soft aperture is provided. By using tandem cell pairs having liquid crystals of opposite chirality, but of different pitch, and with lenses of different curvature, beams of different wavelengths which are projected colinearly along the path may be individually tailored in spatial intensity profile. 11 figs.

  7. Growth and optical property of methyl para hydroxybenzoate sodium dihydrate single crystals

    NASA Astrophysics Data System (ADS)

    Karunagaran, N.; Ramasamy, P.

    2013-06-01

    Methyl parahydroxybenzoate sodium dihydrate (MHBN), a novel semiorganic single crystal has been grown by slow evaporation solution technique (SEST). Single crystal of MHBN with the size of 30 × 30 × 10 mm3 has been grown using methanol as a solvent. The crystal structure of MHBN has been confirmed by single crystal X-ray diffraction. The grown crystals were subjected to powder X-ray diffraction studies. The optical transparency was studied using UV-VIS spectrophotometer and it was found that the crystal is having good optical transparency. The mechanical strength of the grown crystal is measured using Vickers microhardness tester. Thermal properties of the MHBN crystals were studied.

  8. Magneto-Optical Relaxation Measurements of Functionalized Nanoparticles as a Novel Biosensor

    PubMed Central

    Aurich, Konstanze; Glöckl, Gunnar; Nagel, Stefan; Weitschies, Werner

    2009-01-01

    Measurements of magneto-optical relaxation signals of magnetic nanoparticles functionalized with biomolecules are a novel biosensing tool. Upon transmission of a laser beam through a nanoparticle suspension in a pulsed magnetic field, the properties of the laser beam change. This can be detected by optical methods. Biomolecular binding events leading to aggregation of nanoparticles are ascertainable by calculating the relaxation time and from this, the hydrodynamic diameters of the involved particles from the optical signal. Interaction between insulin-like growth factor 1 (IGF-1) and its antibody was utilized for demonstration of the measurement setup applicability as an immunoassay. Furthermore, a formerly developed kinetic model was utilized in order to determine kinetic parameters of the interaction. Beside utilization of the method as an immunoassay it can be applied for the characterization of diverse magnetic nanoparticles regarding their size and size distribution. PMID:22408511

  9. High-sensitivity DNA biosensor based on optical fiber taper interferometer coated with conjugated polymer tentacle.

    PubMed

    Huang, Yunyun; Tian, Zhuang; Sun, Li-Peng; Sun, Dandan; Li, Jie; Ran, Yang; Guan, Bai-Ou

    2015-10-19

    A sensitive bio-probe to in situ detect unlabeled single-stranded DNA targets based on optical microfiber taper interferometer coated by a high ordered pore arrays conjugated polymer has been presented. The polymer coating serves as tentacles to catch single-stranded DNA molecules by π-π conjugated interaction and varies the surface refractive index of the optical microfiber. The microfiber taper interferometer translates the refractive index information into wavelength shift of the interference fringe. The sensor exhibits DNA concentration sensitivity of 2.393 nm/log M and the lowest detection ability of 10(-10) M or even lower. PMID:26480357

  10. PEG Functionalization of Whispering Gallery Mode Optical Microresonator Biosensors to Minimize Non-Specific Adsorption during Targeted, Label-Free Sensing

    PubMed Central

    Wang, Fanyongjing; Anderson, Mark; Bernards, Matthew T.; Hunt, Heather K.

    2015-01-01

    Whispering Gallery Mode (WGM) optical microresonator biosensors are a powerful tool for targeted detection of analytes at extremely low concentrations. However, in complex environments, non-specific adsorption can significantly reduce their signal to noise ratio, limiting their accuracy. To overcome this, poly(ethylene glycol) (PEG) can be employed in conjunction with appropriate recognition elements to create a nonfouling surface capable of detecting targeted analytes. This paper investigates a general route for the addition of nonfouling elements to WGM optical biosensors to reduce non-specific adsorption, while also retaining high sensitivity. We use the avidin-biotin analyte-recognition element system, in conjunction with PEG nonfouling elements, as a proof-of-concept, and explore the extent of non-specific adsorption of lysozyme and fibrinogen at multiple concentrations, as well as the ability to detect avidin in a concentration-dependent fashion. Ellipsometry, contact angle measurement, fluorescence microscopy, and optical resonator characterization methods were used to study non-specific adsorption, the quality of the functionalized surface, and the biosensor’s performance. Using a recognition element ratio to nonfouling element ratio of 1:1, we showed that non-specific adsorption could be significantly reduced over the controls, and that high sensitivity could be maintained. Due to the frequent use of biotin-avidin-biotin sandwich complexes in functionalizing sensor surfaces with biotin-labeled recognition elements, this chemistry could provide a common basis for creating a non-fouling surface capable of targeted detection. This should improve the ability of WGM optical biosensors to operate in complex environments, extending their application towards real-world detection. PMID:26213937

  11. Thermo-optical properties and nonlinear optical response of smectic liquid crystals containing gold nanoparticles.

    PubMed

    de Melo, P B; Nunes, A M; Omena, L; do Nascimento, S M S; da Silva, M G A; Meneghetti, M R; de Oliveira, I N

    2015-10-01

    The present work is devoted to the study of the thermo-optical and nonlinear optical properties of smectic samples containing gold nanoparticles with different shapes. By using the time-resolved Z-scan technique, we determine the effects of nanoparticle addition on the critical behavior of the thermal diffusivity and thermo-optical coefficient at the vicinity of the smectic-A-nematic phase transition. Our results reveal that introduction of gold nanoparticles affects the temperature dependence of thermo-optical parameters, due to the local distortions in the orientational order and heat generation provided by guest particles during the laser exposure. Further, we show that a nonlinear optical response may take place at temperatures where the smectic order is well established. We provide a detailed discussion of the effects associated with the introduction gold nanoparticles on the mechanisms behind the thermal transport and optical nonlinearity in liquid-crystal samples. PMID:26565262

  12. Thermo-optical properties and nonlinear optical response of smectic liquid crystals containing gold nanoparticles

    NASA Astrophysics Data System (ADS)

    de Melo, P. B.; Nunes, A. M.; Omena, L.; Nascimento, S. M. S. do; da Silva, M. G. A.; Meneghetti, M. R.; de Oliveira, I. N.

    2015-10-01

    The present work is devoted to the study of the thermo-optical and nonlinear optical properties of smectic samples containing gold nanoparticles with different shapes. By using the time-resolved Z-scan technique, we determine the effects of nanoparticle addition on the critical behavior of the thermal diffusivity and thermo-optical coefficient at the vicinity of the smectic-A -nematic phase transition. Our results reveal that introduction of gold nanoparticles affects the temperature dependence of thermo-optical parameters, due to the local distortions in the orientational order and heat generation provided by guest particles during the laser exposure. Further, we show that a nonlinear optical response may take place at temperatures where the smectic order is well established. We provide a detailed discussion of the effects associated with the introduction gold nanoparticles on the mechanisms behind the thermal transport and optical nonlinearity in liquid-crystal samples.

  13. Thermo-Optical Effects and Fiber Optic Sensing Device Based on Polymer Dispersed Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Sirleto, L.; Righini, G. C.; Mahmoud, Aburish; Simoni, F.

    In this article, the thermo-optical properties of polymer dispersed liquid crystals (PDLCs) in confined geometry are experimentally investigated to demonstrate the feasibility of a fiber optic sensing device based on PDLCsE Since an unexpected behavior of PDLCs in confined geometry has been experienced, a systematic study of PDLCs' thermo-optical properties in bulk is presented also to point out principal differences. Finally, bistable all fiber optic temperature sensors, in which a PDLC permits at the same time the opto-mechanical interconnection of two fibers and the modulation of light crossing the device, has been realized and characterized, for the first time. Being the modulation controlled by external temperature, the device has been proven to be suitable for the realization of a heat flow sensor. The sensor presents the typical advantages of both fiber optic sensors and liquid crystal technology. Moreover, due to its small thermal capacity, it should exhibit little influence on thermal equilibrium and, above all, it represents a significant improvement compared to a temperature fiber optic sensor based on liquid crystals (presented in the literature).

  14. Single crystal and polycrystalline CVD diamond for demanding optical applications

    NASA Astrophysics Data System (ADS)

    Dodson, J. M.; Brandon, J. R.; Dhillon, H. K.; Friel, I.; Geoghegan, S. L.; Mollart, T. P.; Santini, P.; Scarsbrook, G. A.; Twitchen, D. J.; Whitehead, A. J.; Wilman, J. J.; de Wit, H.

    2011-06-01

    Diamond's extremely wide transparency, combined with its other exceptional properties including hardness, strength and thermal conductivity make it a desirable material for optical windows. Polycrystalline diamond grown by chemical vapour deposition (CVD) has become the preferred window material for high power CO2 laser systems since its development in the 1990s. The range and availability of diamond materials is expanding, and in recent years has been extended to include CVD single crystal diamond. This paper reviews the quality of these materials, looking at optical scatter and absorption around 1 and 10 microns, along with their thermal and mechanical properties. We also discuss selection of appropriate grades and how they may best be integrated into demanding optical applications.

  15. Optical birefringence of liquid crystals for label-free optical biosensing diagnosis

    PubMed Central

    Nguyen, Tan Tai; Han, Gyeo-Re; Jang, Chang-Hyun; Ju, Heongkyu

    2015-01-01

    Purpose We present a polarization-sensitive optical detection platform for label-free quantitative optical biosensing diagnosis using liquid crystals (LCs). This is capable of determining quantitatively the optical birefringence of optical cells containing LCs, whose orientation depends on the immobilized biomolecules. Patients and methods This technique uses a polarization-dependent double-port detection without any polarizer at a single wavelength and removes the need of aligning optical cells of LCs in the azimuthal direction, with respect to the light path through the optical cell. Thus, this technique enables a stand-alone detection in a relatively compact format without an additional optical instrument, such as a retardation compensator, a Michael–Levy chart, and a spectrophotometer, in order to determine the optical birefringence quantitatively. Results We demonstrate that bovine serum albumin immobilized on the gold surface of the cell hybrid interfaces that support both homeotropic and planar anchoring of LCs causes optical phase retardation change which can be determined quantitatively. We also provide estimation of the zenithal orientation of LCs near the gold surface of the hybrid interfaces, based on the phase retardation determined. The estimated limit of bovine serum albumin detection is approximately 2.1 μM. Conclusion This optical technique with LCs can serve an optical platform for label-free quantitative diagnosis of proteins in a real time manner. PMID:26347013

  16. Optical Nano Antennas: State of the Art, Scope and Challenges as a Biosensor Along with Human Exposure to Nano-Toxicology

    PubMed Central

    Kausar, Abu Sulaiman Mohammad Zahid; Reza, Ahmed Wasif; Latef, Tarik Abdul; Ullah, Mohammad Habib; Karim, Mohammad Ershadul

    2015-01-01

    The concept of optical antennas in physical optics is still evolving. Like the antennas used in the radio frequency (RF) regime, the aspiration of optical antennas is to localize the free propagating radiation energy, and vice versa. For this purpose, optical antennas utilize the distinctive properties of metal nanostructures, which are strong plasmonic coupling elements at the optical regime. The concept of optical antennas is being advanced technologically and they are projected to be substitute devices for detection in the millimeter, infrared, and visible regimes. At present, their potential benefits in light detection, which include polarization dependency, tunability, and quick response times have been successfully demonstrated. Optical antennas also can be seen as directionally responsive elements for point detectors. This review provides an overview of the historical background of the topic, along with the basic concepts and parameters of optical antennas. One of the major parts of this review covers the use of optical antennas in biosensing, presenting biosensing applications with a broad description using different types of data. We have also mentioned the basic challenges in the path of the universal use of optical biosensors, where we have also discussed some legal matters. PMID:25884787

  17. Optical nano antennas: state of the art, scope and challenges as a biosensor along with human exposure to nano-toxicology.

    PubMed

    Kausar, Abu Sulaiman Mohammad Zahid; Reza, Ahmed Wasif; Latef, Tarik Abdul; Ullah, Mohammad Habib; Karim, Mohammad Ershadul

    2015-01-01

    The concept of optical antennas in physical optics is still evolving. Like the antennas used in the radio frequency (RF) regime, the aspiration of optical antennas is to localize the free propagating radiation energy, and vice versa. For this purpose, optical antennas utilize the distinctive properties of metal nanostructures, which are strong plasmonic coupling elements at the optical regime. The concept of optical antennas is being advanced technologically and they are projected to be substitute devices for detection in the millimeter, infrared, and visible regimes. At present, their potential benefits in light detection, which include polarization dependency, tunability, and quick response times have been successfully demonstrated. Optical antennas also can be seen as directionally responsive elements for point detectors. This review provides an overview of the historical background of the topic, along with the basic concepts and parameters of optical antennas. One of the major parts of this review covers the use of optical antennas in biosensing, presenting biosensing applications with a broad description using different types of data. We have also mentioned the basic challenges in the path of the universal use of optical biosensors, where we have also discussed some legal matters. PMID:25884787

  18. Biosensors in Clinical Practice: Focus on Oncohematology

    PubMed Central

    Fracchiolla, Nicola S.; Artuso, Silvia; Cortelezzi, Agostino

    2013-01-01

    Biosensors are devices that are capable of detecting specific biological analytes and converting their presence or concentration into some electrical, thermal, optical or other signal that can be easily analysed. The first biosensor was designed by Clark and Lyons in 1962 as a means of measuring glucose. Since then, much progress has been made and the applications of biosensors are today potentially boundless. This review is limited to their clinical applications, particularly in the field of oncohematology. Biosensors have recently been developed in order to improve the diagnosis and treatment of patients affected by hematological malignancies, such as the biosensor for assessing the in vitro pre-treatment efficacy of cytarabine in acute myeloid leukemia, and the fluorescence resonance energy transfer-based biosensor for assessing the efficacy of imatinib in chronic myeloid leukemia. The review also considers the challenges and future perspectives of biosensors in clinical practice. PMID:23673681

  19. Crystal structure, thermal and optical properties of Benzimidazole benzimidazolium picrate crystal

    NASA Astrophysics Data System (ADS)

    Jagadesan, A.; Peramaiyan, G.; Srinivasan, T.; Kumar, R. Mohan; Arjunan, S.

    2016-02-01

    A new organic framework of benzimidazole with picric acid has been synthesized. A single crystal with a size of 38×10×4 mm3 was grown by a slow evaporation solution growth technique. X-ray diffraction study revealed that the BZP crystal belongs to triclinic system with space group P-1. High resolution X-ray diffraction study shows the absence of grain boundaries without any defects. The thermal stability and specific heat capacity of BZP were investigated by TG/DT and TG/DSC analyses. From the UV-vis-NIR spectral study, optical transmission window and band gap of BZP were found out. The nonlinear refractive index (n2) and third order susceptibility Re(χ(3)) values of BZP crystal are estimated to be 1.73×10-7 cm2/W and 1.26×10-5 esu, respectively using a Z-scan technique.

  20. Studies on Growth and Characterization of bis Thiourea Lead Chloride:. a Novel Nonlinear Optical Crystal

    NASA Astrophysics Data System (ADS)

    Kirubavathi, K.; Selvaraju, K.; Kumararaman, S.

    Single crystals of the metal-organic nonlinear optical material bis thiourea lead chloride were grown from solution growth technique for the first time. The grown crystals were characterized by single crystal X-ray diffraction analysis to confirm the crystal structure. The presence of various functional groups and the coordination of metal ions to thiourea were confirmed by Fourier transform infrared analysis. UV-Vis. spectrum was recorded to study the optical transparency of the grown crystals. The second order nonlinear optical property of the grown crystal was examined by Kurtz powder technique and mechanical behavior was studied by Vickers micro hardness test.

  1. Photonic crystal-based optical filters for operating in second and third optical fiber windows

    NASA Astrophysics Data System (ADS)

    Zamani, Mehdi

    2016-04-01

    In this paper, the filtering properties of photonic crystals (PCs) to perform narrow-channel transmission-type filters in second and third optical fiber telecommunication windows have been studied. Filtration of these zero dispersion and low-loss windows have simultaneously been established by utilizing of a triple-cavity transmission-type one-dimensional PC that provides perfect transmittances and narrow-channels at corresponding wavelengths. Such PC-based optical filter can be used in wavelength division multiplexing (WDM) optical communications systems.

  2. Biosensor application of resonance coupling to thin film planar waveguides on side-polished optical fiber

    NASA Astrophysics Data System (ADS)

    Ecke, Wolfgang; Andreev, Andrey; Csaki, Andrea; Kirsch, Konstantin; Schroeder, Kerstin; Wieduwilt, Torsten; Willsch, Reinhardt

    2011-05-01

    Optical resonance coupling between a side-polished fiber and thin film waveguides has been investigated in the presence of biochemical adsorbates. The shift of the resonance wavelengths was found to be highly sensitive to the capture of target DNA recognition elements with Au nanoparticle markers, allowing for a sensitivity limit of 10 particles on the side-polished fiber core area (2000 μm²) during on-line measurements using a polychromator spectrometer.

  3. Piezo-optic, photoelastic, and acousto-optic properties of SrB4O7 crystals.

    PubMed

    Mytsyk, Bohdan; Demyanyshyn, Natalia; Martynyuk-Lototska, Irina; Vlokh, Rostyslav

    2011-07-20

    On the basis of studies of the piezo-optic effect, it has been shown that SrB(4)O(7) crystals can be used as efficient acousto-optic materials in the vacuum ultraviolet spectral range. The full matrices of piezo-optic and photoelastic coefficients have been experimentally obtained for these crystals. The acousto-optic figure of merit and the diffraction efficiency have been estimated for both the visible and deep ultraviolet spectral ranges. PMID:21772372

  4. Optical Spectroscopy of Defects in Yttrium Orthovanadate (YVO4) Crystals

    NASA Astrophysics Data System (ADS)

    Sze Cheung, Wai; Wiechmann, Katrina; Sheldon, Peter; Yochum, Hank; Yochum, Marcia

    2007-04-01

    Yttrium orthovanadate (YVO4) is an insulating crystal used in several important and emerging optical technologies such as a solid-state laser host material and in fiber optic components for telecommunications. We are engaged in a study of the growth-related and radiation-related point defects that result in discoloration of commercial quality YVO4. These defects can reduce the usefulness of the material. Alternatively, these same defects may actually play a beneficial role in the use of YVO4 for other applications, such as the observed Anti-Stokes Luminescence (light which is converted to a higher energy due to a two-photon process in the crystal) which could make the YVO4 a candidate for blue lasers. It has been surmised [1] that some of these ``useful'' defects are related to oxygen vacancies in the crystal, so we are exploring the effects on defects after annealing the YVO4 in Oxygen and other gas atmospheres. [1] Anti-Stokes emission in undoped YVO4, W. Ryba-Romanowksi, S. Golab, P. Solarz, and G. Dominiak-Dzik, Applied Physics Letters, 80, 1183 (2002).

  5. Comparison of formats for the development of fiber-optic biosensors utilizing sol-gel derived materials entrapping fluorescently-labelled protein.

    PubMed

    Flora, K; Brennan, J D

    1999-10-01

    The development of fiber-optic biosensors requires that a biorecognition element and a fluorescent reporter group be immobilized at or near the surface of an optical element such as a planar waveguide or optical fiber. In this study, we examined a model biorecognition element-reporter group couple consisting of human serum albumin that was site-selectively labelled at Cys 34 with iodoacetoxy-nitrobenzoxadiazole (HSA-NBD). The labelled protein was encapsulated into sol-gel derived materials that were prepared either as monoliths, as beads that were formed at the distal tip of a fused silica optical fiber, or as thin films that were dipcast along the length of a glass slide or optical fiber. For fiber-based studies, the entrapped protein was excited using a helium-cadmium laser that was launched into a single optical fiber, and emission was separated from the incident radiation using a perforated mirror beam-splitter, and detected using a monochromator-photomultiplier tube assembly. Changes in fluorescence intensity were generated by denaturant-induced conformational changes in the protein or by iodide quenching. The analytical parameters of merit for the different encapsulation formats, including minimum protein loading level, response time and limit-of-detection, were examined, as were factors such as protein accessibility, leaching and photobleaching. Overall, the results indicated that both beads and films were suitable for biosensor development. In both formats, a substantial fraction of the entrapped protein remained accessible, and the entrapped protein retained a large degree of conformational flexibility. Thin films showed the most rapid response times, and provided good detection limits for a model analyte. However, the entrapment of proteins into beads at the distal tip of fibers provided better signal-to-noise and signal-to-background ratios, and required less protein for preparation. Hence, beads appear to be the most viable method for interfacing of

  6. Automated mineral identification algorithm using optical properties of crystals

    NASA Astrophysics Data System (ADS)

    Aligholi, Saeed; Khajavi, Reza; Razmara, Morteza

    2015-12-01

    A method has been developed to automatically characterize the type of mineral phases by means of digital image analysis using optical properties of crystals. The method relies on microscope automation, digital image acquisition, image processing and analysis. Two hundred series of digital images were taken from 45 standard thin sections using a digital camera mounted on a conventional microscope and then transmitted to a computer. CIELab color space is selected for the processing, in order to effectively employ its well-defined color difference metric for introducing appropriate color-based feature. Seven basic optical properties of minerals (A. color; B. pleochroism; C. interference color; D. birefringence; E. opacity; F. isotropy; G. extinction angle) are redefined. The Local Binary Pattern (LBP) operator and modeling texture is integrated in the Mineral Identification (MI) scheme to identify homogeneous regions in microscopic images of minerals. The accuracy of mineral identification using the method was %99, %98, %96 and %95 for biotite, hornblende, quartz and calcite minerals, respectively. The method is applicable to other minerals and phases for which individual optical properties of crystals do not provide enough discrimination between the relevant phases. On the basis of this research, it can be concluded that if the CIELab color space and the local binary pattern (LBP) are applied, it is possible to recognize the mineral samples with the accuracy of more than 98%.

  7. Recent development of nonlinear optical borate crystals for UV generation

    NASA Astrophysics Data System (ADS)

    Mori, Y.; Yap, Y. K.; Kamimura, T.; Yoshimura, M.; Sasaki, T.

    2002-02-01

    Recent development of high-power solid-state UV radiation by nonlinear optical (NLO) borate crystals is reviewed. The performance of such UV light sources has rapidly improved in the past five years because of the superior NLO properties of CsLiB 6O 10 (CLBO) crystals. The performance of such UV light sources also depends on the reliability of the NLO crystals. The relation between the bulk laser-induced damage threshold (LIDT), dislocation density and UV absorption of CsLiB 6O 10 (CLBO) was investigated. A newly developed synthesis process allows the growth of CLBO crystals with LIDT 2.5-fold higher than those grown by the conventional top-seeded solution growth (TSSG) technique. High-quality CLBO possesses lower dislocation density and smaller absorption of UV light ( λ=266 nm) than conventional CLBO. Reduction of the dislocation density can suppress absorption of UV light that helps to enhance the resistance of CLBO to laser-induced damages, to alleviate thermal dephasing during high-power generation of UV light and thus strengthen the reliability of CLBO for UV light generation.

  8. Adaptive optics fundus camera using a liquid crystal phase modulator

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Tatsuo; Nakazawa, Naoki; Bessho, Kenichiro; Kitaguchi, Yoshiyuki; Maeda, Naoyuki; Fujikado, Takashi; Mihashi, Toshifumi

    2008-05-01

    We have developed an adaptive optics (AO) fundus camera to obtain high resolution retinal images of eyes. We use a liquid crystal phase modulator to compensate the aberrations of the eye for better resolution and better contrast in the images. The liquid crystal phase modulator has a wider dynamic range to compensate aberrations than most mechanical deformable mirrors and its linear phase generation makes it easy to follow eye movements. The wavefront aberration was measured in real time with a sampling rate of 10 Hz and the closed loop system was operated at around 2 Hz. We developed software tools to align consecutively obtained images. From our experiments with three eyes, the aberrations of normal eyes were reduced to less than 0.1 μm (RMS) in less than three seconds by the liquid crystal phase modulator. We confirmed that this method was adequate for measuring eyes with large aberrations including keratoconic eyes. Finally, using the liquid crystal phase modulator, high resolution images of retinas could be obtained.

  9. Thermal, optical and spectroscopic characterizations of borate laser crystals

    SciTech Connect

    Chavoutier, M.; Jubera, V.; Veber, P.; Velazquez, M.; Viraphong, O.; Hejtmanek, J.; Decourt, R.; Debray, J.; Menaert, B.; Segonds, P.; Adamietz, F.; Rodriguez, V.; Manek-Hoenninger, I.; Fargues, A.; Descamps, D.; Garcia, A.

    2011-02-15

    The Yb-content Li{sub 6}Ln(BO{sub 3}){sub 3} (Ln: Gd, Y) solid solution has been investigated. Crystal growth has been successful for several compositions. A 22% molar content of ytterbium ions was determined by chemical analysis (ICP). Physical properties relevant to laser operation like mechanical hardness, thermal expansion and thermal conductivity were measured on single crystals. Optical measurements, including refractive index and low temperature spectroscopy, were also performed. Finally, the effect of the Y/Gd ratio is discussed. -- Graphical abstract: Several solid solutions of a rare earth borate were studied. The figure illustrates one of these single crystals obtained by Czochralski and shows thermal behaviour and absorption spectra at low temperature. Display Omitted Research highlights: {yields} We have grown by Czochralski method five Li{sub 6}Ln(BO{sub 3}){sub 3} (Ln=Y, Gd,Yb) single crystals. {yields} Chemical, physical and spectroscopic characteristics are reported. {yields} Data relevant to laser operation are listed.

  10. Characterization and Operation of Liquid Crystal Adaptive Optics Phoropter

    SciTech Connect

    Awwal, A; Bauman, B; Gavel, D; Olivier, S; Jones, S; Hardy, J L; Barnes, T; Werner, J S

    2003-02-05

    Adaptive optics (AO), a mature technology developed for astronomy to compensate for the effects of atmospheric turbulence, can also be used to correct the aberrations of the eye. The classic phoropter is used by ophthalmologists and optometrists to estimate and correct the lower-order aberrations of the eye, defocus and astigmatism, in order to derive a vision correction prescription for their patients. An adaptive optics phoropter measures and corrects the aberrations in the human eye using adaptive optics techniques, which are capable of dealing with both the standard low-order aberrations and higher-order aberrations, including coma and spherical aberration. High-order aberrations have been shown to degrade visual performance for clinical subjects in initial investigations. An adaptive optics phoropter has been designed and constructed based on a Shack-Hartmann sensor to measure the aberrations of the eye, and a liquid crystal spatial light modulator to compensate for them. This system should produce near diffraction-limited optical image quality at the retina, which will enable investigation of the psychophysical limits of human vision. This paper describes the characterization and operation of the AO phoropter with results from human subject testing.

  11. Optical measurement of Verdet constants of two electrooptic crystals and their applications to optical sensors

    NASA Astrophysics Data System (ADS)

    Li, Changsheng

    2013-12-01

    Verdet constants of beta-barium borate (BBO) and lead molybdate (PMO) crystals are measured experimentally by the method of comparison with a block of terbium-doped glass with a known Verdet constant. Experimental setups mainly include two prism polarizers, a solenoid and ac current supply, and signal processing circuits. The influences of light intensity fluctuation, applied magnetic field and signal processing circuits on measurement result of Verdet constant can be removed by using the method of comparison. For light wavelength of 635nm, the measured Verdet constants respectively are 5.80+/-0.06 rad/(T.m) for the BBO crystal and 54.6+/-1.1 rad/(T.m) for the PMO crystal. A novel optical current sensor based on electrooptic compensation is designed in principle using the BBO crystal.

  12. Photonic-crystal-based all-optical NOT logic gate.

    PubMed

    Singh, Brahm Raj; Rawal, Swati

    2015-12-01

    In the present paper, we have utilized the concept of photonic crystals for the implementation of an optical NOT gate inverter. The designed structure has a hexagonal arrangement of silicon rods in air substrate. The logic function is based on the phenomenon of the existence of the photonic bandgap and resulting guided modes in defect photonic crystal waveguides. We have plotted the transmission, extinction ratio, and tolerance analysis graphs for the structure, and it has been observed that the maximum output is obtained for a telecom wavelength of 1.554 μm. Dispersion curves are obtained using the plane wave expansion method, and the transmission is simulated using the finite element method. The proposed structure is applicable for photonic integrated circuits due to its simple structure and clear operating principle. PMID:26831380

  13. DNA biosensors implemented on PNA-functionalized microstructured optical fibers Bragg gratings

    NASA Astrophysics Data System (ADS)

    Candiani, A.; Giannetti, S.; Cucinotta, A.; Bertucci, A.; Manicardi, A.; Konstantaki, M.; Margulis, W.; Pissadakis, S.; Corradini, R.; Selleri, S.

    2013-05-01

    A novel DNA sensing platform based on a Peptide Nucleic Acid - functionalized Microstructured Optical Fibers gratings has been demonstrated. The inner surface of different MOFs has been functionalized using PNA probes, OligoNucleotides mimic that are well suited for specific DNA target sequences detection. The hybrid sensing systems were tested for optical DNA detection of targets of relevance in biomedical application, using the cystic fibrosis gene mutation, and food-analysis, using the genomic DNA from genetic modified organism soy flour. After the solutions of DNA molecules has been infiltrated inside the fibers capillaries and hybridization has occurred, oligonucleotidefunctionalized gold nanoparticles were infiltrated and used to form a sandwich-like system to achieve signal amplification. Spectral measurements of the reflected signal reveal a clear wavelength shift of the reflected modes when the infiltrated complementary DNA matches with the PNA probes placed on the inner fiber surface. Measurements have also been made using the mismatched DNA solution for the c, containing a single nucleotide polymorphism, showing no significant changes in the reflected spectrum. Several experiments have been carried out demonstrating the reproducibility of the results and the high selectivity of the sensors, showing the simplicity and the potential of this approach.

  14. ZnO Nanorod-Based Non-Enzymatic Optical Glucose Biosensor.

    PubMed

    Sarangi, Sachindra Nath; Nozaki, Shinji; Sahu, Surendra Nath

    2015-06-01

    The highly sensitive, interference-free and non-enzymatic optical sensing of glucose has been made possible for the first time using the hydrothermally synthesized ZnO nanorods. The UV irradiation of glucose-treated ZnO nanorods decomposes glucose into hydrogen peroxide (H2O2) and gluconic acid by UV oxidation. The ZnO nanorods play the role of a catalyst similar to the oxidase used in the enzymatic glucose sensors. The photoluminescence (PL) intensity of the near-band edge emission of the ZnO nanorods linearly decreased with the increased concentration of H2O2. Therefore, the glucose concentration is monitored over the wide range of 0.5-30 mM, corresponding to 9-540 mg/dL. The concentration range of the linear region in the calibration curve is suitable for its clinical use as a glucose sensor, because the glucose concentration of human serum is typically in the range of 80-120 mg/dL. In addition, the optical glucose sensor made of the ZnO nanorods is free from interference by bovin serum albumin, ascorbic acid or uric acid, which are also present in human blood. The non-enzymatic ZnO-nanorod sensor has been demonstrated with human serum samples from both normal persons and diabetic patients. There is a good agreement between the glucose concentrations measured by the PL quenching and standard clinical methods. PMID:26353588

  15. Dual optical biosensors for imaging microRNA-1 during myogenesis.

    PubMed

    Kang, Won Jun; Cho, Ye Lim; Chae, Ju Ri; Lee, Jong Doo; Ali, Bahy A; Al-Khedhairy, Abdulaziz A; Lee, Chang Hyun; Kim, Soonhag

    2012-09-01

    Dual optical microRNA (miRNA) imaging systems, bioluminescent reporter gene (a signal-off mechanism)- or fluorescent molecular beacon (MB) (a signal-on mechanism)-based miRNA imaging system, have individually allowed us to sense miRNA biogenesis in a noninvasive and iterative manner. Both of these imaging systems have shortcomings with respect to image quality. Therefore, we designed a dual optical imaging systems by simultaneous imaging of a miRNA-1 reporter gene (CMV/Gluc/3xPT_miR-1) and miRNA-1 MB in a single cell to overcome these limitations and used it to visualize miRNA-1, a highly expressed miRNA in cardiac and skeletal muscle. During myogenic differentiation of C2C12 cells, the bioluminescence intensity from CMV/Gluc/3xPT_miR-1 revealed a miRNA-1-dependent gradual decrease and the fluorescence intensity from miR-1 MB demonstrated a miRNA-1-dependent gradual increase both in vitro and in vivo. The dual miRNA-1 imaging systems, which provides the complementary imaging information about miRNA biogenesis, could be useful to sense miRNA expression during various biologic processes. PMID:22698721

  16. Programmable lattices of optical vortices in nematic liquid crystal

    NASA Astrophysics Data System (ADS)

    Barboza, R.; Assanto, G.; Bortolozzo, U.; Clerc, M. G.; Residori, S.; Vidal-Henriquez, E.

    2015-09-01

    Using self-induced vortex-like defects in the nematic liquid crystal layer of a light valve with photo-sensible wall, we demonstrate the realization of programable optical vortices lattices with arbitrary configuration in space. On each lattice site, every matter vortex acts as a photonic spin-to-orbital momentum coupler and an array of circularly polarized input beams is converted into an output array of vortex beams with topological charges consistent with the vortex matter lattice. The vortex arrangements are explained the basis of light-induced matter defects and topological rules.

  17. Exploring optical mechanotransduction in fluorescent liquid crystal elastomers.

    PubMed

    Garcia-Amorós, Jaume; Bassaganyas, Sergi; Velasco, Dolores

    2016-02-21

    Carbazole-based nematic liquid single crystal elastomers switch their fluorescence mechanically on demand enabling a fast optical mechanotransduction under ambient conditions. The identification of the key factors controlling such process is of utmost importance since it might lead to a significant improvement of the transducing abilities of these smart materials. In particular, variations in the length of the fluorophore flexible spacer translates in a distinct mutual interaction between both mesogenic and fluorogenic platforms, giving rise thereby to functional materials with a significantly different mechanofluorescent behaviour. PMID:26863282

  18. Optical biosensor system with integrated microfluidic sample preparation and TIRF based detection

    NASA Astrophysics Data System (ADS)

    Gilli, Eduard; Scheicher, Sylvia R.; Suppan, Michael; Pichler, Heinz; Rumpler, Markus; Satzinger, Valentin; Palfinger, Christian; Reil, Frank; Hajnsek, Martin; Köstler, Stefan

    2013-05-01

    There is a steadily growing demand for miniaturized bioanalytical devices allowing for on-site or point-of-care detection of biomolecules or pathogens in applications like diagnostics, food testing, or environmental monitoring. These, so called labs-on-a-chip or micro-total analysis systems (μ-TAS) should ideally enable convenient sample-in - result-out type operation. Therefore, the entire process from sample preparation, metering, reagent incubation, etc. to detection should be performed on a single disposable device (on-chip). In the early days such devices were mainly fabricated using glass or silicon substrates and adapting established fabrication technologies from the electronics and semiconductor industry. More recently, the development focuses on the use of thermoplastic polymers as they allow for low-cost high volume fabrication of disposables. One of the most promising materials for the development of plastic based lab-on-achip systems are cyclic olefin polymers and copolymers (COP/COC) due to their excellent optical properties (high transparency and low autofluorescence) and ease of processing. We present a bioanalytical system for whole blood samples comprising a disposable plastic chip based on TIRF (total internal reflection fluorescence) optical detection. The chips were fabricated by compression moulding of COP and microfluidic channels were structured by hot embossing. These microfluidic structures integrate several sample pretreatment steps. These are the separation of erythrocytes, metering of sample volume using passive valves, and reagent incubation for competitive bioassays. The surface of the following optical detection zone is functionalized with specific capture probes in an array format. The plastic chips comprise dedicated structures for simple and effective coupling of excitation light from low-cost laser diodes. This enables TIRF excitation of fluorescently labeled probes selectively bound to detection spots at the microchannel surface

  19. Optical spectroscopy of single crystals and nanoscale films of pentacene

    NASA Astrophysics Data System (ADS)

    He, Rui

    Growing interest in organic molecular semiconductors is stimulated by their promising applications in flexible devices. Transistors based on pentacene have reached device mobilities comparable to amorphous Si. This creates incentives for fundamental studies of organic molecular crystals and nanoscale structures. The research presented in this dissertation demonstrates optical spectroscopy venues for studies of organic molecular semiconductors. Pentacene single crystals and nanoscale films, reaching sub-monolayer thickness, are probed by photoluminescence and resonance Raman spectroscopies. The studies of single crystals reveal new physics linked to intrinsic and extrinsic excitations and provide benchmarks for evaluating the results in nanoscale films. By studying single crystals with different degrees of purities, I identified extrinsic luminescence bands in high quality crystals. Large resonance enhancements of Raman intensities occur when photon energies overlap intrinsic luminescence bands of free and self-trapped excitons. A four-step Raman scattering mechanism is proposed to describe the resonance processes with the self-trapped state. Photoluminescence spectra of discontinuous clusters and ultra-thin films with few monolayers in thickness reveal two fundamental excitations that are assigned to Davydov doublets of the lowest singlet exciton. The observations suggest that pentacene nanoscale films develop a structure with two molecules per unit cell. Pentacene monolayers deposited on substrates functionalized with the polymer of poly alpha-methylstyrene exhibit great lateral uniformity. These monolayers display sharp and intense free exciton luminescence bands which offer giant resonance enhancements of Raman scattering intensities. The enhancements enable the first observations of low-lying lattice modes from pentacene monolayers. The lattice modes show characteristic changes when the number of layers is increased. The low-lying lattice modes reveal inter

  20. Improving the performance of gold nanohole array biosensors by controlling the optical collimation conditions.

    PubMed

    Weber de Menezes, Jacson; Thesing, Anderson; Valsecchi, Chiara; Armas, Luis E G; Brolo, Alexandre G

    2015-07-20

    An experimental investigation on how the bulk and surface sensitivities of gold nanohole arrays fabricated by interference lithography affect the degree of white light beam collimation is presented. The optical transmission response of nanohole arrays has been recorded by focused and collimated beam transmission spectra. The results show that both the bulk and surface sensitivities for the collimated case are much larger than for the focused case. In particular, the shape of the spectra was dependent on the degree of beam collimation. The results showed that improved sensing performance (around 3.5 times) and higher figure of merit (around 4.4 times) can be obtained by simply adjusting the incident/collection experimental conditions in transmission measurements. PMID:26367835

  1. Easy to Use Plastic Optical Fiber-Based Biosensor for Detection of Butanal

    PubMed Central

    Varriale, Antonio; Staiano, Maria; Di Pietrantonio, Fabio; Notargiacomo, Andrea; Zeni, Luigi; D’Auria, Sabato

    2015-01-01

    The final goal of this work is to achieve a selective detection of butanal by the realization of a simple, small-size and low cost experimental approach. To this end, a porcine odorant-binding protein was used in connection with surface plasmon resonance transduction in a plastic optical fiber tool for the selective detection of butanal by a competitive assay. This allows to reduce the cost and the size of the sensing device and it offers the possibility to design a “Lab-on-a-chip” platform. The obtained results showed that this system approach is able to selectively detect the presence of butanal in the concentration range from 20 μM to 1000 μM. PMID:25789470

  2. Plasmonic nanoparticles: Towards the fabrication of biosensors

    NASA Astrophysics Data System (ADS)

    Shen, Hui

    2015-07-01

    Au and Ag nanoparticles are mainly employed in the fabrication of biosensors owing to their unique optical properties compared to other noble metal nanoparticles. Many biosensors are fabricated for the rapid detection of different analytes such as organic and inorganic molecules, biomolecules like DNA, proteins, biotoxins and pathogens. In this mini review we mainly discuss on the usage of Au and Ag nanoparticles for the fabrication of colorimetric, SERS and two photon based photoluminescence biosensors.

  3. Dispersion of the temperature-noncritical frequency conversion and birefringence in biaxial optical crystals

    SciTech Connect

    Grechin, Sergei G; Dmitriev, Valentin G; Dyakov, Vladimir A; Pryalkin, Vladimir I

    2004-05-31

    Dispersion of the temperature-noncritical frequency conversion (phase matching) and birefringence in biaxial crystals is considered. The possibility of simultaneous realisation of these processes during SHG in a KTP crystal is discussed. (nonlinear optical phenomena)

  4. Broadband optical switch based on liquid crystal dynamic scattering.

    PubMed

    Geis, M W; Bos, P J; Liberman, V; Rothschild, M

    2016-06-27

    This work demonstrates a novel broadband optical switch, based on dynamic-scattering effect in liquid crystals (LCs). Dynamic-scattering-mode technology was developed for display applications over four decades ago, but was displaced in favor of the twisted-nematic LCs. However, with the recent development of more stable LCs, dynamic scattering provides advantages over other technologies for optical switching. We demonstrate broadband polarization-insensitive attenuation of light directly passing thought the cell by 4 to 5 orders of magnitude at 633 nm. The attenuation is accomplished by light scattering to higher angles. Switching times of 150 μs to 10% transmission have been demonstrated. No degradation of devices is found after hundreds of switching cycles. The light-rejection mechanism is due to scattering, induced by disruption of LC director orientation with dopant ion motion with an applied electric field. Angular dependence of scattering is characterized as a function of bias voltage. PMID:27410544

  5. Optical properties and diffraction effects in opal photonic crystals.

    PubMed

    Balestreri, Alessandra; Andreani, Lucio Claudio; Agio, Mario

    2006-09-01

    Optical properties of fcc opals oriented along the [111] direction are calculated by means of a scattering-matrix approach based on approximating each sphere with cylindrical slices. The use of a plane-wave basis in each layer allows distinguishing zero-order reflection and transmission from higher-order (diffraction) spectra. Optical spectra at large values of the angle of incidence indicate the presence of diffraction effects and of polarization mixing along the LW orientation. Reflectance and transmittance in the high-energy region show a rich spectral dependence and compare reasonably well with recent experimental observations on polystyrene opals. Diffraction spectra as a function of the number of layers display an oscillatory behavior, pointing to the existence of a Pendellösung phenomenon, related to the exchange of energy between two propagating modes in the investigated three-dimensional photonic crystal. This phenomenon could be observed in transmittance experiments on high-quality opals with controlled thickness. PMID:17025760

  6. Optically responsive liquid crystal microfibers for display and nondisplay applications

    NASA Astrophysics Data System (ADS)

    Buyuktanir, Ebru A.; West, John L.; Frey, Margaret W.

    2011-03-01

    We demonstrate the fabrication and characterization of optically-tunable and stimuli-responsive electrospun microfibers endowed with liquid crystal (LC) functionality. The highly flexible LC microfibers are electrospun from a solution of 4- pentyl-4'-cyanobiphenyl (5CB) and polylactic acid (PLA) in chloroform/acetone solvent. In the electrospinning process, the low molecular weight 5CB phase-separates and self-assembles to form a planarly aligned nematic core within a PLA shell. Most importantly, the orientation of LC domains and, therefore, the optical properties of the 5CB/PLA fibers can be tuned by application of an external electric field. These properties of LC fibers may, in turn, be utilized to fabricate a variety of photonic textiles, and ultimately may introduce an entirely new manufacturing process where weaving will reach well beyond the roll-to-roll manufacturing envisioned for the currently emerging flexible displays printed on flexible plastic substrates.

  7. Crystal growth, spectral, optical and thermal properties of semiorganic nonlinear optical material: Picolinic acid hydrochloride

    NASA Astrophysics Data System (ADS)

    Gowri, S.; Uma Devi, T.; Sajan, D.; Surendra Dilip, C.; Chandramohan, A.; Lawrence, N.

    2013-06-01

    The bulk single crystal of 2-picolinic acid hydrochloride (PHCL) (a semi-organic nonlinear optical material of dimensions 25 × 15 × 10 mm3) was successfully grown by slow solvent evaporation technique. The XRD results revealed the cell parameters and the centrosymmetric nature of the crystal structure. FT-IR spectral study identified the functional groups, nature of bonding and their bond strength. The UV-Vis-NIR studies recognized the optical transmittance window and the lower cut off wavelength of the PHCL crystal and thus it could be performed as a NLO material. 1H NMR and 13CNMR spectra were correlated with the XRD standard for the molecular structure reveals harmony of the materials. Thermal properties of the crystal were studied by thermo gravimetric analysis (TGA) and differential thermal analysis (DTA); the derived kinetic parameter values support the intuitive association of picolinicacid and HCl leads to the spontaneous formation of PHCL with a first order reaction. The presence of a proton and a proton acceptor groups provide the necessary stability to induce charge asymmetry in the PHCL structure. The load dependent hardness values of the crystal were measured by microhardness testing.

  8. Optical and Acoustic Device Applications of Ferroelastic Crystals

    NASA Astrophysics Data System (ADS)

    Meeks, Steven Wayne

    This dissertation presents the discovery of a means of creating uniformly periodic domain gratings in a ferroelastic crystal of neodymium pentaphosphate (NPP). The uniform and non-uniform domain structures which can be created in NPP have the potential applications as tunable active gratings for lasers, tunable diffraction gratings, tunable Bragg reflection gratings, tunable acoustic filters, optical modulators, and optical domain wall memories. The interaction of optical and acoustic waves with ferroelastic domain walls in NPP is presented in detail. Acoustic amplitude reflection coefficients from a single domain wall in NPP are much larger than other ferroelastic-ferroelectrics such as gadolinium molybdate (GMO). Domain walls of NPP are used to make two demonstration acoustic devices: a tunable comb filter and a tunable delay line. The tuning process is accomplished by moving the position of the reflecting surface (the domain wall). A theory of the reflection of optical waves from NPP domain walls is discussed. The optical reflection is due to a change in the polarization of the wave, and not a change in the index, as the wave crosses the domain wall. Theoretical optical power reflection coefficients show good agreement with the experimentally measured values. The largest optical reflection coefficient of a single domain wall is at a critical angle and is 2.2% per domain wall. Techniques of injecting periodic and aperiodic domain walls into NPP are presented. The nucleation process of the uniformly periodic domain gratings in NPP is described in terms of a newly-discovered domain structure, namely the ferroelastic bubble. A ferroelastic bubble is the elastic analogue to the well-known magnetic bubble. The period of the uniformly periodic domain grating is tunable from 100 to 0.5 microns and the grating period may be tuned relatively rapidly. The Bragg efficiency of these tunable gratings is 77% for an uncoated crystal. Several demonstration devices which use

  9. Optical Properties of Small Ice Crystals with Black Carbon Inclusions

    NASA Astrophysics Data System (ADS)

    Yang, X.; Geier, M.; Arienti, M.

    2013-12-01

    The optical properties of ice crystals play a fundamental role in modeling atmospheric radiation and hydrological cycle, which are critical in monitoring climate change. While Black Carbon (BC) is recognized as the dominant absorber with positive radiative forcing (warming) (Ramanathan & Carmichael, 2008), in-situ observations (Cappa, et al, 2012) indicate that the characterization of the mixing state of BC with ice crystals and other non-BC particles in global climate models (Ghan & Schwartz, 2007) needs further investigation. The limitation in the available mixing models is due to the drastically different absorbing properties of BC compared to other aerosols. We explore the scattering properties of ice crystals (in shapes commonly found in cirrus clouds and contrails - Yang, et al. 2012) with the inclusion of BC particles. The Discrete Dipole Approximation (DDA) (Yurkin & Hoekstra, 2011) is utilized to directly calculate the optical properties of the crystals with multiple BC inclusions, modeled as a distribution of spheres. The results are then compared with the most popular models of internal and external mixing (Liou, et al. 2011). The DDA calculations are carried out over a broad range of BC particle sizes and volume fractions within the crystal at the 532 nm wavelength and for ice crystals smaller than 50 μm. The computationally intensive database generated in this study is critical for understanding the effect of different types of BC inclusions on the atmosphere radiative forcing. Examples will be discussed to illustrate the modification of BC optical properties by encapsulation in ice crystals and how the parameterization of the BC mixing state in global climate models can be improved. Acknowledgements Support by Sandia National Laboratories' LDRD (Laboratory Directed Research and Development) is gratefully acknowledged. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of

  10. Increase of bulk optical damage threshold fluences of KDP crystals by laser irradiation and heat treatment

    DOEpatents

    Swain, J.E.; Stokowski, S.E.; Milam, D.; Kennedy, G.C.; Rainer, F.

    1982-07-07

    The bulk optical damage threshold fluence of potassium dihydrogen phosphate (KDP) crystals is increased by irradiating the crystals with laser pulses of duration 1 to 20 nanoseconds of increasing fluence, below the optical damage threshold fluence for untreated crystals, or by baking the crystals for times of the order of 24 hours at temperatures of 110 to 165/sup 0/C, or by a combination of laser irradiation and baking.

  11. Synthesis, Growth, Spectral and Optical Properties of Glycinyl Urea Single Crystal

    SciTech Connect

    Shanthi, N. Theresita; Selvarajan, P.; Rose, A. S. J. Lucia

    2011-10-20

    Single crystals of Glycinyl Urea were grown from aqueous solution by slow evaporation technique at room temperature. The cell parameters of the grown crystals were estimated by Single X-ray diffraction studies. The functional groups present in the grown crystals were ascertained using FTIR spectrum analysis. UV-visible transmittance spectrum was recorded to study the optical transparency of the grown crystal. The non-linear optical property has been tested by Kurtz powder technique.

  12. Silicon coupled-resonator optical-waveguide-based biosensors using light-scattering pattern recognition with pixelized mode-field-intensity distributions

    PubMed Central

    Wang, Jiawei; Yao, Zhanshi; Lei, Ting; Poon, Andrew W.

    2014-01-01

    Chip-scale, optical microcavity-based biosensors typically employ an ultra-high-quality microcavity and require a precision wavelength-tunable laser for exciting the cavity resonance. For point-of-care applications, however, such a system based on measurements in the spectral domain is prone to equipment noise and not portable. An alternative microcavity-based biosensor that enables a high sensitivity in an equipment-noise-tolerant and potentially portable system is desirable. Here, we demonstrate the proof-of-concept of such a biosensor using a coupled-resonator optical-waveguide (CROW) on a silicon-on-insulator chip. The sensing scheme is based on measurements in the spatial domain, and only requires exciting the CROW at a fixed wavelength and imaging the out-of-plane elastic light-scattering intensity patterns of the CROW. Based on correlating the light-scattering intensity pattern at a probe wavelength with the light-scattering intensity patterns at the CROW eigenstates, we devise a pattern-recognition algorithm that enables the extraction of a refractive index change, Δn, applied upon the CROW upper-cladding from a calibrated set of correlation coefficients. Our experiments using an 8-microring CROW covered by NaCl solutions of different concentrations reveal a Δn of ~1.5 × 10−4 refractive index unit (RIU) and a sensitivity of ~752 RIU−1, with a noise-equivalent detection limit of ~6 × 10−6 RIU. PMID:25519726

  13. Silicon coupled-resonator optical-waveguide-based biosensors using light-scattering pattern recognition with pixelized mode-field-intensity distributions.

    PubMed

    Wang, Jiawei; Yao, Zhanshi; Lei, Ting; Poon, Andrew W

    2014-01-01

    Chip-scale, optical microcavity-based biosensors typically employ an ultra-high-quality microcavity and require a precision wavelength-tunable laser for exciting the cavity resonance. For point-of-care applications, however, such a system based on measurements in the spectral domain is prone to equipment noise and not portable. An alternative microcavity-based biosensor that enables a high sensitivity in an equipment-noise-tolerant and potentially portable system is desirable. Here, we demonstrate the proof-of-concept of such a biosensor using a coupled-resonator optical-waveguide (CROW) on a silicon-on-insulator chip. The sensing scheme is based on measurements in the spatial domain, and only requires exciting the CROW at a fixed wavelength and imaging the out-of-plane elastic light-scattering intensity patterns of the CROW. Based on correlating the light-scattering intensity pattern at a probe wavelength with the light-scattering intensity patterns at the CROW eigenstates, we devise a pattern-recognition algorithm that enables the extraction of a refractive index change, Δn, applied upon the CROW upper-cladding from a calibrated set of correlation coefficients. Our experiments using an 8-microring CROW covered by NaCl solutions of different concentrations reveal a Δn of ~1.5 × 10(-4) refractive index unit (RIU) and a sensitivity of ~752 RIU(-1), with a noise-equivalent detection limit of ~6 × 10(-6) RIU. PMID:25519726

  14. Fabrication and optical transmission characteristics of polymers woodpile photonic crystal structures with different crystal planes

    NASA Astrophysics Data System (ADS)

    Chen, Ling-Jing; Dong, Xian-Zi; Zhao, Yuan-Yuan; Zhang, Yong-Liang; Liu, Jie; Zheng, Mei-Ling; Duan, Xuan-Ming; Zhao, Zhen-Sheng

    2015-10-01

    The photonic band gap effect which originates from the translational invariance of the periodic lattice of dielectrics has been widely applied in the technical applications of microwave, telecommunication and visible wavelengths. Among the various examples, polymers based three dimensional (3D) photonic crystals (PhCs) have attracted considerable interest because they can be easily fabricated by femo-second (fs) ultrafast laser direct writing (DLW) method. However, it is difficult to realize complete band gap in polymers PhCs due to the low index contrast between polymers and air. Here, we report the design and experimental realization of light's nonreciprocal propagation in woodpile PhCs fabricated with DLW method. Firstly, we fabricated several polymers woodpile PhCs on glass substrate with different crystal planes. The Fourier transform infrared spectroscopy (FTIR) measurements are in agreement with the theoretical predictions, which proves the validity and the accuracy of our DLW method. Further measurements of the transmission spectra with respect to the incident angle reveal that the surface crystal planes and incident wave vectors play important roles in the optical response. Furthermore, we designed and fabricated a 30° PhC wedge. And we find nonreciprocal transmission effect between the forward and backward waves, resulting from the nonsymmetrical refraction of the light in different planes. Our results may find potential applications in future 3D photonic integrated circuits and pave the way for the fabrication of other photonic and optical devices with DLW method.

  15. Label-free, disposable fiber-optic biosensors for DNA hybridization detection.

    PubMed

    Yin, Ming-jie; Wu, Chuang; Shao, Li-yang; Chan, Wing Kin Edward; Zhang, A Ping; Lu, Chao; Tam, Hwa-yaw

    2013-04-01

    A novel and highly sensitive fiber-optic DNA sensor based on a thin-core fiber modal interferometer (TCFMI) is demonstrated by using a layer-by-layer (LbL) self-assembly technology. Poly(ethylenimine) (PEI), poly(acrylic acid) (PAA) and single-stranded DNA (ssDNA) were used for the preparation of a polyelectrolyte multilayer film for DNA detection. The film thickness was measured through a surface profilometer. The surface morphologies of (PEI/PAA)4, (PEI/PAA)4.5 and (PEI/PAA)4(PEI/DNA)1 multilayer films were characterized by atomic force microscopy. The fabricated DNA sensors were tested with different types of target ssDNA solutions with a concentration of 1 μM. The results show that the sensitivity of the TCFMI-based ssDNA sensor is 0.27 nm/matched-base at the concentration of 1 μM and can even distinguish the number of matched bases of ssDNA chains. PMID:23397583

  16. Self-assembled, photoluminescent peptide hydrogel as a versatile platform for enzyme-based optical biosensors.

    PubMed

    Kim, Jae Hong; Lim, Seong Yoon; Nam, Dong Heon; Ryu, Jungki; Ku, Sook Hee; Park, Chan Beum

    2011-01-15

    A self-assembled peptide hydrogel consisting of Fmoc-diphenylalanine has been employed as a biosensing platform through the encapsulation of enzyme bioreceptors (e.g., glucose oxidase or horseradish peroxidase) and fluorescent reporters (e.g., CdTe and CdSe quantum dots). Enzymes and quantum dots (QDs) were physically immobilized within the hydrogel matrix in situ in a single step by simply mixing aqueous solution containing QDs and enzymes with monomeric peptide (Fmoc-diphenylalanine) solution. By using atomic force microscopy and scanning transmission electron microscopy, we observed that the self-assembled peptide hydrogel had a three-dimensional network of nanofibers (with a diameter of approximately 70-90 nm) that physically hybridized with QDs and encapsulated enzyme bioreceptors with a minimal leakage. We successfully applied the peptide hydrogel to the detection of analytes such as glucose and toxic phenolic compounds by using a photoluminescence quenching of the hybridized QDs. The Michaelis-Menten constant (K(M)) of the photoluminescent peptide hydrogel was found to be 3.12 mM (GOx for glucose) and 0.82 mM (HRP for hydroquinone), respectively, which were much lower than those of conventional gel materials. These results suggest that the peptide hydrogel is an alternative optical biosensing platform with practical advantages such as simple fabrication via self-assembly, efficient diffusion of target analytes, and high encapsulation efficiencies for fluorescent reporters and bioreceptors. PMID:20171868

  17. Functional Polymers in Protein Detection Platforms: Optical, Electrochemical, Electrical, Mass-Sensitive, and Magnetic Biosensors

    PubMed Central

    Hahm, Jong-in

    2011-01-01

    The rapidly growing field of proteomics and related applied sectors in the life sciences demands convenient methodologies for detecting and measuring the levels of specific proteins as well as for screening and analyzing for interacting protein systems. Materials utilized for such protein detection and measurement platforms should meet particular specifications which include ease-of-mass manufacture, biological stability, chemical functionality, cost effectiveness, and portability. Polymers can satisfy many of these requirements and are often considered as choice materials in various biological detection platforms. Therefore, tremendous research efforts have been made for developing new polymers both in macroscopic and nanoscopic length scales as well as applying existing polymeric materials for protein measurements. In this review article, both conventional and alternative techniques for protein detection are overviewed while focusing on the use of various polymeric materials in different protein sensing technologies. Among many available detection mechanisms, most common approaches such as optical, electrochemical, electrical, mass-sensitive, and magnetic methods are comprehensively discussed in this article. Desired properties of polymers exploited for each type of protein detection approach are summarized. Current challenges associated with the application of polymeric materials are examined in each protein detection category. Difficulties facing both quantitative and qualitative protein measurements are also identified. The latest efforts on the development and evaluation of nanoscale polymeric systems for improved protein detection are also discussed from the standpoint of quantitative and qualitative measurements. Finally, future research directions towards further advancements in the field are considered. PMID:21691441

  18. Modal reduction in single crystal sapphire optical fiber

    NASA Astrophysics Data System (ADS)

    Cheng, Yujie; Hill, Cary; Liu, Bo; Yu, Zhihao; Xuan, Haifeng; Homa, Daniel; Wang, Anbo; Pickrell, Gary

    2015-10-01

    A type of single crystal sapphire optical fiber (SCSF) design is proposed to reduce the number of guided modes via a highly dispersive cladding with a periodic array of high- and low-index regions in the azimuthal direction. The structure retains a "core" region of pure single crystal (SC) sapphire in the center of the fiber and a "cladding" region of alternating layers of air and SC sapphire in the azimuthal direction that is uniform in the radial direction. The modal characteristics and confinement losses of the fundamental mode were analyzed via the finite element method by varying the effective core diameter and the dimensions of the "windmill"-shaped cladding. The simulation results showed that the number of guided modes was significantly reduced in the windmill fiber design, as the radial dimension of the air and SC sapphire cladding regions increase with corresponding decrease in the azimuthal dimension. It is anticipated that the windmill SCSF will readily improve the performance of current fiber optic sensors in the harsh environment and potentially enable those that were limited by the extremely large modal volume of unclad SCSF.

  19. Lasing and waveguiding in smectic A liquid crystal optical fibers.

    PubMed

    Peddireddy, Karthik; Jampani, V S R; Thutupalli, Shashi; Herminghaus, Stephan; Bahr, Christian; Muševič, Igor

    2013-12-16

    We demonstrate a new class of soft matter optical fibers, which are self-assembled in a form of smectic-A liquid crystal microtubes grown in an aqueous surfactant dispersion of a smectic-A liquid crystal. The diameter of the fibers is highly uniform and the fibers are highly birefringent. They are characterized by a line topological defect in the core of the fiber with an optical axis pointing from the defect core towards the surface. We demonstrate guiding of light along the fiber and Whispering Gallery Mode (WGM) lasing in a plane perpendicular to the fiber. The light guiding as well as the lasing threshold are significantly dependent on the polarization of the excitation beam. The observed threshold for WGM lasing is very low (≈ 75μJ/cm(2)) when the pump beam polarization is perpendicular to the direction of the laser dye alignment and is similar to the lasing threshold in nematic droplets. The smectic-A fibers are soft and flexible and can be manipulated with laser tweezers demonstrating a promising approach for realization of soft photonic circuits. PMID:24514602

  20. Modal reduction in single crystal sapphire optical fiber

    SciTech Connect

    Cheng, Yujie; Hill, Cary; Liu, Bo; Yu, Zhihao; Xuan, Haifeng; Homa, Daniel; Wang, Anbo; Pickrell, Gary

    2015-10-12

    A new type of single crystal sapphire optical fiber (SCSF) design is proposed to reduce the number of guided modes via a highly dispersive cladding with a periodic array of high and low index regions in the azimuthal direction. The structure retains a “core” region of pure single crystal (SC) sapphire in the center of the fiber and a “cladding” region of alternating layers of air and SC sapphire in the azimuthal direction that is uniform in the radial direction. The modal characteristics and confinement losses of the fundamental mode were analyzed via the finite element method by varying the effective core diameter and the dimensions of the “windmill” shaped cladding. The simulation results showed that the number of guided modes were significantly reduced in the “windmill” fiber design, as the radial dimension of the air and SC sapphire cladding regions increase with corresponding decrease in the azimuthal dimension. It is anticipated that the “windmill” SCSF will readily improve the performance of current fiber optic sensors in the harsh environment and potentially enable those that were limited by the extremely large modal volume of unclad SCSF.

  1. Modal reduction in single crystal sapphire optical fiber

    DOE PAGESBeta

    Cheng, Yujie; Hill, Cary; Liu, Bo; Yu, Zhihao; Xuan, Haifeng; Homa, Daniel; Wang, Anbo; Pickrell, Gary

    2015-10-12

    A new type of single crystal sapphire optical fiber (SCSF) design is proposed to reduce the number of guided modes via a highly dispersive cladding with a periodic array of high and low index regions in the azimuthal direction. The structure retains a “core” region of pure single crystal (SC) sapphire in the center of the fiber and a “cladding” region of alternating layers of air and SC sapphire in the azimuthal direction that is uniform in the radial direction. The modal characteristics and confinement losses of the fundamental mode were analyzed via the finite element method by varying themore » effective core diameter and the dimensions of the “windmill” shaped cladding. The simulation results showed that the number of guided modes were significantly reduced in the “windmill” fiber design, as the radial dimension of the air and SC sapphire cladding regions increase with corresponding decrease in the azimuthal dimension. It is anticipated that the “windmill” SCSF will readily improve the performance of current fiber optic sensors in the harsh environment and potentially enable those that were limited by the extremely large modal volume of unclad SCSF.« less

  2. Chiral multichromic single crystals for optical devices (LDRD 99406).

    SciTech Connect

    Kemp, Richard Alan; Felix, Ana M. (University of New Mexico, Albuquerque, NM)

    2006-12-01

    This report summarizes our findings during the study of a novel system that yields multi-colored materials as products. This system is quite unusual as it leads to multi-chromic behavior in single crystals, where one would expect that only a single color would exist. We have speculated that these novel solids might play a role in materials applications such as non-linear optics, liquid crystal displays, piezoelectric devices, and other similar applications. The system examined consisted of a main-group alkyl compound (a p block element such as gallium or aluminum) complexed with various organic di-imines. The di-imines had substituents of two types--either alkyl or aromatic groups attached to the nitrogen atoms. We observed that single crystals, characterized by X-ray crystallography, were obtained in most cases. Our research during January-July, 2006, was geared towards understanding the factors leading to the multi-chromic nature of the complexes. The main possibilities put forth initially considered (a) the chiral nature of the main group metal, (b) possible reduction of the metal to a lower-valent, radical state, (c) the nature of the ligand(s) attached to the main group metal, and (d) possible degradation products of the ligand leading to highly-colored products. The work carried out indicates that the most likely explanation considered involves degradation of the aromatic ligands (a combination of (c) and (d)), as the experiments performed can clearly rule out (a) and (b).

  3. Interaction of high-density and low-density lipoproteins to solid surfaces coated with cholesterol as determined by an optical fiber-based biosensor

    NASA Astrophysics Data System (ADS)

    Singh, Bal R.; Poirier, Michelle A.

    1993-05-01

    In recent years, the use of fiber optics has become an important tool in biomedicine and biotechnology. We are involved in developing and employing a new system which, through the use of fiber optics, may be capable of measuring the content of cholesterol and lipoproteins in blood samples in real time. In the optical fiber-based biosensor, a laser beam having a wavelength of 512 nm (green light) is launched into an optical fiber, which transmits the light to its distal end. An evanescent wave (travelling just outside the fiber core) is used to excite rhodamine-labelled HDL or LDL which become bound to the fiber or to fiber-bound molecules. The fluorescence (red light) is coupled back into the fiber and detected with a photodiode. Preliminary work has involved testing of high density lipoprotein (HDL) binding to a cholesterol-coated fiber and to a bare fiber and low density lipoprotein (LDL) binding to a cholesterol-coated fiber. A significant difference was observed in the binding rate of HDL (5 (mu) g/mL and lower) to a bare fiber as opposed to a cholesterol-coated fiber. The binding rate of HDL (5 (mu) g/mL) to a bare fiber was 7.5 (mu) V/sec and to a cholesterol-coated fiber was 3.5 (mu) V/sec. We have calculated the binding affinity of LDL to a cholesterol- coated fiber as 1.4 (mu) M-1. These preliminary results suggest that the optical fiber-based biosensor can provide a unique and promising approach to the analysis of lipoprotein interaction with solid surfaces and with cholesterol. More importantly, the results suggest that this technique may be used to assess the binding of blood proteins to artificial organs/tissues, and to measure the amount of cholesterol, HDL and LDL in less than a minute.

  4. Crystal structure, growth and characterizations of a novel organic third-order nonlinear optical crystal: guanidinium cinnamate

    NASA Astrophysics Data System (ADS)

    Dhavamurthy, M.; Raja, R.; Syed Suresh Babu, K.; Mohan, R.

    2016-08-01

    Guanidinium cinnamate (GUCN), a single crystal, was grown by slow evaporation technique. Single-crystal X-ray diffraction study revealed that GUCN crystal belongs to monoclinic crystal system with the space group P21/c. Thermal studies revealed that the GUCN is thermally stable up to 238 °C. The optical transmittance studies were carried out for the crystal, and the lower cutoff wavelength of the grown crystal was observed at 322 nm. The luminescent study showed that the GUCN crystal has high degree of luminescence. Third-order nonlinear refractive index n2, nonlinear absorption coefficient β and susceptibility χ(3) parameters were estimated by Z-scan technique. The four independent tensor coefficients ɛ11, ɛ22, ɛ33 and ɛ13 of dielectric permittivities for monoclinic GUCN were calculated. The mechanical properties of the grown crystals were studied using Vickers micro-hardness tester at different planes.

  5. Optical harmonic generation in hollow-core photonic-crystal fibres: analysis of optical losses and phase-matching conditions

    SciTech Connect

    Naumov, A N; Zheltikov, Aleksei M

    2002-02-28

    We consider hollow-core fibres with a microstructure photonic-crystal cladding, which open a unique opportunity of implementing nonlinear-optical interactions of waveguide modes with transverse sizes on the order of several microns in the gas phase. Phase-matching conditions for optical harmonic generation can be improved in higher waveguide modes of hollow-core photonic-crystal fibres by optimising parameters of the gas medium filling the fibre and characteristics of the fibre. (optical fibres)

  6. Improvement of up-converting phosphor technology-based biosensor

    NASA Astrophysics Data System (ADS)

    Xie, Chengke; Huang, Lihua; Zhang, Youbao; Guo, Xiaoxian; Qu, Jianfeng; Huang, Huijie

    2008-12-01

    A novel biosensor based on up-converting phosphor technology (UPT) was developed several years ago. It is a kind of optical biosensor using up-converting phosphor (UCP) particles as the biological marker. From then on, some improvements have been made for this UPT-based biosensor. The primary aspects of the improvement lie in the control system. On one hand, the hardware of the control system has been optimized, including replacing two single chip microcomputers (SCM) with only one, the optimal design of the keyboard interface circuit and the liquid crystal module (LCM) control circuit et al.. These result in lower power consumption and higher reliability. On the other hand, a novel signal processing algorithm is proposed in this paper, which can improve the automation and operating simplicity of the UPT-based biosensor. It has proved to have high sensitivity (~ng/ml), high stability and good repeatability (CV<5%), which is better than the former system. It can meet the need of some various applications such as rapid immunoassay, chemical and biological detection and so on.

  7. Optical, elemental and structural analyses of acetoacetanilide single crystals for nonlinear optical applications.

    PubMed

    Vijayan, N; Rani, Neelam; Bhagavannarayana, G; Haranath, D; Jayabharathi, J; Wahab, M A; Das, S

    2012-07-01

    Single crystals of acetoacetanilide have been successfully grown by slow evaporation solution growth method at room temperature. The grown crystal belongs to orthorhombic crystal system having the lattice dimensions of a=8.686Å, b=11.104Å, c=19.232Å. Its crystalline perfection was examined by home-made high resolution X-ray diffractometer (HRXRD), and found that that the quality of the specimen is reasonable. The presence of carbon, hydrogen and nitrogen were experimentally determined by elemental analysis and that are in good agreement with the theoretically calculated values. Its laser damage threshold, phase matching and second harmonic generation efficiency were determined by using Nd:YAG laser as a source. Optical behavior of acetoacetanilide was examined by using photoluminescence studies. Its hyerpolarizability and HOMO-LUMO energies were calculated by using density functional theory (DFT). PMID:22465771

  8. Optical Basicity and Nepheline Crystallization in High Alumina Glasses

    SciTech Connect

    Rodriguez, Carmen P.; McCloy, John S.; Schweiger, M. J.; Crum, Jarrod V.; Winschell, Abigail E.

    2011-02-25

    The purpose of this study was to find compositions that increase waste loading of high-alumina wastes beyond what is currently acceptable while avoiding crystallization of nepheline (NaAlSiO4) on slow cooling. Nepheline crystallization has been shown to have a large impact on the chemical durability of high-level waste glasses. It was hypothesized that there would be some composition regions where high-alumina would not result in nepheline crystal production, compositions not currently allowed by the nepheline discriminator. Optical basicity (OB) and the nepheline discriminator (ND) are two ways of describing a given complex glass composition. This report presents the theoretical and experimental basis for these models. They are being studied together in a quadrant system as metrics to explore nepheline crystallization and chemical durability as a function of waste glass composition. These metrics were calculated for glasses with existing data and also for theoretical glasses to explore nepheline formation in Quadrant IV (passes OB metric but fails ND metric), where glasses are presumed to have good chemical durability. Several of these compositions were chosen, and glasses were made to fill poorly represented regions in Quadrant IV. To evaluate nepheline formation and chemical durability of these glasses, quantitative X-ray diffraction (XRD) analysis and the Product Consistency Test were conducted. A large amount of quantitative XRD data is collected here, both from new glasses and from glasses of previous studies that had not previously performed quantitative XRD on the phase assemblage. Appendix A critically discusses a large dataset to be considered for future quantitative studies on nepheline formation in glass. Appendix B provides a theoretical justification for choice of the oxide coefficients used to compute the OB criterion for nepheline formation.

  9. All-optical intensity modulation of near infrared light in a liquid crystal channel waveguide

    NASA Astrophysics Data System (ADS)

    d'Alessandro, Antonio; Asquini, Rita; Trotta, Marco; Gilardi, Giovanni; Beccherelli, Romeo; Khoo, Iam Choon

    2010-08-01

    We demonstrate a nonlinear optical channel waveguide made of E7 nematic liquid crystal infiltrated in a silica on silicon groove. Near infrared light at the wavelength of 1560 nm fiber coupled to the core of the liquid crystal waveguide was optically modulated by an optical beam with power below 25 mW by exploiting the optical Freedericks transition. By modeling the optical molecular reorientation in the nematic liquid crystal confined in a waveguiding geometry we are able to reproduce the experimental results.

  10. Linear and nonlinear optical, mechanical, electrical and surface studies of a novel nonlinear optical crystal - Manganese mercury thiocyanate (MMTC)

    NASA Astrophysics Data System (ADS)

    Josephine Usha, R.; Sagayaraj, P.; Joseph, V.

    2014-12-01

    The highly efficient nonlinear optical single crystal of manganese mercury thiocyanate has been grown from slow evaporation solvent technique. The second harmonic generation and optical transmittance of the grown crystal are studied by Kurtz and Perry powder technique and spectroscopic absorbance spectrum. Mechanical behaviour is analyzed using Vickers microhardness test. The dielectric response of the grown crystal is studied as a function of the temperature and the results are discussed. Further, electronic properties such as plasma energy, Penngap, Fermi energy and electronic polarizability are evaluated. Third order nonlinear optical studies are performed using by single beam Z-scan technique using Nd:YAG laser and parameters such as nonlinear refractive index n2, absorption co-efficient β and nonlinear optical susceptibility χ(3) are evaluated for the grown crystal. The surface of the grown crystal is analyzed with field emission scanning electron microscope and atomic force microscope analyses.

  11. Linear and nonlinear optical, mechanical, electrical and surface studies of a novel nonlinear optical crystal - manganese mercury thiocyanate (MMTC).

    PubMed

    Josephine Usha, R; Sagayaraj, P; Joseph, V

    2014-12-10

    The highly efficient nonlinear optical single crystal of manganese mercury thiocyanate has been grown from slow evaporation solvent technique. The second harmonic generation and optical transmittance of the grown crystal are studied by Kurtz and Perry powder technique and spectroscopic absorbance spectrum. Mechanical behaviour is analyzed using Vickers microhardness test. The dielectric response of the grown crystal is studied as a function of the temperature and the results are discussed. Further, electronic properties such as plasma energy, Penngap, Fermi energy and electronic polarizability are evaluated. Third order nonlinear optical studies are performed using by single beam Z-scan technique using Nd:YAG laser and parameters such as nonlinear refractive index n2, absorption co-efficient β and nonlinear optical susceptibility χ((3)) are evaluated for the grown crystal. The surface of the grown crystal is analyzed with field emission scanning electron microscope and atomic force microscope analyses. PMID:24945865

  12. All-optical signal processing at 10 GHz using a photonic crystal molecule

    SciTech Connect

    Combrié, Sylvain; Lehoucq, Gaëlle; Junay, Alexandra; De Rossi, Alfredo; Malaguti, Stefania; Bellanca, Gaetano; Trillo, Stefano; Ménager, Loic; Peter Reithmaier, Johann

    2013-11-04

    We report on 10 GHz operation of an all-optical gate based on an Indium Phosphide Photonic Crystal Molecule. Wavelength conversion and all-optical mixing of microwave signals are demonstrated using the 2 mW output of a mode locked diode laser. The spectral separation of the optical pump and signal is crucial in suppressing optical cross-talk.

  13. Growth, structure and optical properties of nonlinear optical crystal BaZnBO3F

    NASA Astrophysics Data System (ADS)

    Xia, Mingjun; Li, R. K.

    2016-01-01

    Nonlinear optical (NLO) crystal BaZnBO3F (BZBF) with the size of about 20×20×0.5 mm3 is obtained from BaF2-NaF flux, and single crystal X-ray diffraction reveals that it belongs to space group P 6 ̅ with cell parameters of a=5.1045(6) Å, c=4.3116(10) Å and Z=1. In the structure of BZBF, the BO3 planar triangles are interconnected through O atoms from ZnO3F2 trigonal bipyramid to form (Zn3B3O6F6) twelve-membered rings (12-MRs), then the layers which are built with condensation from 12-MRs at ab plane, are further linked by the apical F from ZnO3F2 to form three dimensional framework along the c direction. The title crystal exhibits high transmittance in the range of 300-3000 nm with a UV transmission cutoff at 223 nm according to transmission spectra. Powder SHG tests indicate that the effective NLO coefficient of BZBF crystal is about 2.8 times that of KH2PO4 (KDP) crystal due to perfect alignment of the BO3 groups.

  14. Optical, dielectric and microhardness studies on <1 0 0> directed ADP crystal

    NASA Astrophysics Data System (ADS)

    Rajesh, P.; Ramasamy, P.

    2009-09-01

    <1 0 0> directed ammonium dihydrogen phosphate single crystal has been grown using the uniaxially solution-crystallization method of Sankaranarayanan-Ramasamy (SR). The size of the grown crystal is 40 mm in diameter and 50 mm in thickness. The grown crystals were characterized by UV-vis spectroscopy, Vickers hardness and dielectric studies. Comparing the <1 0 0> plane of the conventional method grown ADP crystal with <1 0 0> directed SR method grown ADP crystal, optical transparency, dielectric constant and Vickers hardness number are increased and dielectric loss is decreased in SR method grown crystal.

  15. Synthesis, crystal growth, structural, thermal, optical and mechanical properties of solution grown 4-methylpyridinium 4-hydroxybenzoate single crystal.

    PubMed

    Sudhahar, S; Krishna Kumar, M; Sornamurthy, B M; Mohan Kumar, R

    2014-01-24

    Organic nonlinear optical material, 4-methylpyridinium 4-hydroxybenzoate (4MPHB) was synthesized and single crystal was grown by slow evaporation solution growth method. Single crystal and powder X-ray diffraction analyses confirm the structure and crystalline perfection of 4MPHB crystal. Infrared, Raman and NMR spectroscopy techniques were used to elucidate the functional groups present in the compound. TG-DTA analysis was carried out in nitrogen atmosphere to study the decomposition stages, endothermic and exothermic reactions. UV-visible and Photoluminescence spectra were recorded for the grown crystal to estimate the transmittance and band gap energy respectively. Linear refractive index, birefringence, and SHG efficiency of the grown crystal were studied. Laser induced surface damage threshold and mechanical properties of grown crystal were studied to assess the suitability of the grown crystals for device applications. PMID:24184578

  16. Optical nonreciprocal transmission in an asymmetric silicon photonic crystal structure

    SciTech Connect

    Wu, Zheng; Chen, Juguang; Ji, Mengxi; Huang, Qingzhong; Xia, Jinsong; Wang, Yi E-mail: ywangwnlo@mail.hust.edu.cn; Wu, Ying E-mail: ywangwnlo@mail.hust.edu.cn

    2015-11-30

    An optical nonreciprocal transmission (ONT) is realized by employing the nonlinear effects in a compact asymmetric direct-coupled nanocavity-waveguide silicon photonic crystal structure with a high loaded quality factor (Q{sub L}) of 42 360 and large extinction ratio exceeding 30 dB. Applying a single step lithography and successive etching, the device can realize the ONT in an individual nanocavity, alleviating the requirement to accurately control the resonance of the cavities. A maximum nonreciprocal transmission ratio of 21.1 dB as well as a working bandwidth of 280 pm in the telecommunication band are obtained at a low input power of 76.7 μW. The calculated results by employing a nonlinear coupled-mode model are in good agreement with the experiment.

  17. Path to meter class single crystal silicon (SCSi) space optics

    NASA Astrophysics Data System (ADS)

    McCarter, Douglas R.

    2012-03-01

    With the global financial crisis affecting funding for space systems development, customers are calling for lower cost systems. Yet, at the same time, these lower cost systems must have increased thermal response to operational environments and load survivability. We submit that single crystal silicon (SCSi) meets both of these requirements. This paper will highlight some key SCSi material properties, discuss the opportunities that led to the development of McCarter processing methods, and present the latest steps in the manufacturing path of McCarter Mirrors using SCSi, GFB (glass frit bonding) and MSF (McCarter super finish), including the concept drawing of a one meter SCSi lightweight mirror, which together sets up the last step toward a lower cost, high performing one meter SCSi space optic.

  18. Development of optical systems. [holographic technique for monitoring crystal growth

    NASA Technical Reports Server (NTRS)

    Vikram, Chandra S.

    1995-01-01

    Several key aspects of multi-color holography and laser speckle technique to study holographic reconstructions are considered in the report. Holographic fringe contrast in two-color holography in the presence of a fluid cell in the object beam is discussed in detail. A specific example of triglycine sulfate crystal growth is also considered. A breadboard design using fiber optics and diode lasers for three-color holography for fluid experiments is presented. A possible role of multi-color holography in various new applications is summarized. Finally, the use of a a laser speckle technique is demonstrated for the study of holographic reconstructions. The demonstration is performed using a Spacelab 3 hologram.

  19. Optical switch based on the electrically controlled liquid crystal interface.

    PubMed

    Komar, Andrei A; Tolstik, Alexei L; Melnikova, Elena A; Muravsky, Alexander A

    2015-06-01

    The peculiarities of the linearly polarized light beam reflection at the interface within the bulk of a nematic liquid crystal (NLC) cell with different orientations of the director are analyzed. Two methods to create the interface are considered. Combination of the planar and homeotropic orientations of the NLC director is realized by means of a spatially structured electrode under the applied voltage. In-plane patterned azimuthal alignment of the NLC director is created by the patterned rubbing alignment technique. All possible orthogonal orientations of the LC director are considered; the configurations for realization of total internal reflection are determined. The revealed relationship between the propagation of optical beams in a liquid crystal material and polarization of laser radiation has enabled realization of the spatial separation for the orthogonally polarized light beams at the interface between two regions of NLC with different director orientations (domains). Owing to variations in the applied voltage and, hence, in the refractive index gradient, the light beam propagation directions may be controlled electrically. PMID:26192675

  20. Single crystal growth, structural characterization, thermal and optical properties of a novel organometallic nonlinear optical crystal: MnHg(SCN) 4(C 2H 5NO) 2

    NASA Astrophysics Data System (ADS)

    Wang, X. Q.; Cheng, X. F.; Zhang, S. J.; Xu, D.; Zhang, G. H.; Sun, Z. H.; Yu, F. P.; Liu, X. J.; Liu, W. L.; Chen, C. L.

    2010-02-01

    A novel potentially useful organometallic nonlinear optical crystal, manganese mercury thiocyanate-bis(N-methylformamide), MnHg(SCN) 4(C 2H 5NO) 2 (MMTN) has been prepared, and large highly-optical quality single crystals with dimensions up to 29×28×14 mm 3 have been grown. The structural characterization, thermal and optical properties of the grown crystals are investigated. The growth morphology was obtained by indexing the X-ray powder diffraction data and compared with that deducing from the single crystal structure data using the Bravais-Friedel-Donnay-Harker model. The thermal analysis reveals that MMTN crystal possesses good physicochemical stability. The specific heat of the crystal is 635.1 J mol -1 K -1 at 300 K. The thermal expansion coefficient along the a, b, and c axis is α1=6.18×10 -5 K -1, α2=3.91×10 -5 K -1 and α3=9.53×10 -6 K -1, respectively. The laser damage threshold of MMTN crystal is about 225.7 MW/cm 2 with pulse width of 18 ns at 1064 nm. The powder second harmonic efficiency of the crystal is about 1.1 pm/V and the UV transparency cutoff is 354 nm, which are interpreted on the basis of the crystal structure with the Molecular Orbital theory using a GAUSSIAN03 program.

  1. Ultra-fast optical switches using 1D polymeric photonic crystals

    NASA Astrophysics Data System (ADS)

    Katouf, R.; Komikado, T.; Itoh, M.; Yatagai, T.; Umegaki, S.

    2005-12-01

    We report fabrication of ultra-fast optical switches operated at a wavelength of 1064 nm using spin-coated one-dimensional polymeric photonic crystals doped with nonlinear-optical dyes. The optical switches are controlled either by an applied electric-field voltage or by a pump light by use of two different optical-configurations. The response time of the electro-optic switch and the all-optical switch are limited by the applied voltage and the laser used, respectively. The polymeric photonic crystals can be easily fabricated with low cost.

  2. Optical and electrical characteristics of pure and doped potassium hydrogen tartrate single crystals

    NASA Astrophysics Data System (ADS)

    Quasim, I.; Firdous, A.; Khosa, S. K.; Kotru, P. N.

    2009-08-01

    The optical and electrical characteristics of pure, sodium- and lithium-doped potassium hydrogen tartrate crystals grown by the gel technique are reported. An optical absorption study conducted in the UV-Vis range of 200-800 nm reveals the transparency of these crystals in the entire visible range but not in the ultraviolet range. The optical band gap of pure potassium hydrogen tartrate crystals is found to be dependent on doping by Na or Li ions. The non-linear optical behaviour of these crystals is reported and explained. The electrical properties of pure and doped potassium hydrogen tartrate crystals are studied by measuring electrical resistivity from 80 to 300 K. It is shown that while pure potassium hydrogen tartrate crystal is an insulator at room temperature (300 K), doping by Na or Li ions makes it a semiconductor. The results have been explained in terms of the variable range hopping model.

  3. Visualising apoptosis in live zebrafish using fluorescence lifetime imaging with optical projection tomography to map FRET biosensor activity in space and time.

    PubMed

    Andrews, Natalie; Ramel, Marie-Christine; Kumar, Sunil; Alexandrov, Yuriy; Kelly, Douglas J; Warren, Sean C; Kerry, Louise; Lockwood, Nicola; Frolov, Antonina; Frankel, Paul; Bugeon, Laurence; McGinty, James; Dallman, Margaret J; French, Paul M W

    2016-04-01

    Fluorescence lifetime imaging (FLIM) combined with optical projection tomography (OPT) has the potential to map Förster resonant energy transfer (FRET) readouts in space and time in intact transparent or near transparent live organisms such as zebrafish larvae, thereby providing a means to visualise cell signalling processes in their physiological context. Here the first application of FLIM OPT to read out biological function in live transgenic zebrafish larvae using a genetically expressed FRET biosensor is reported. Apoptosis, or programmed cell death, is mapped in 3-D by imaging the activity of a FRET biosensor that is cleaved by Caspase 3, which is a key effector of apoptosis. Although apoptosis is a naturally occurring process during development, it can also be triggered in a variety of ways, including through gamma irradiation. FLIM OPT is shown here to enable apoptosis to be monitored over time, in live zebrafish larvae via changes in Caspase 3 activation following gamma irradiation at 24 hours post fertilisation. Significant apoptosis was observed at 3.5 hours post irradiation, predominantly in the head region. PMID:26753623

  4. Optical biosensors for environmental monitoring based on computational and biotechnological tools for engineering the photosynthetic D1 protein of Chlamydomonas reinhardtii.

    PubMed

    Giardi, Maria Teresa; Scognamiglio, Viviana; Rea, Giuseppina; Rodio, Giuseppe; Antonacci, Amina; Lambreva, Maya; Pezzotti, Gianni; Johanningmeier, Udo

    2009-10-15

    Homology-based protein modelling and computational screening followed by virtual mutagenesis analyses were used to identify functional amino acids in the D1 protein of the photosynthetic electron transfer chain interacting with herbicides. A library of functional mutations in the unicellular green alga Chlamydomonas reinhardtii for preparing biomediators was built and their interactions with herbicides were calculated. D1 proteins giving the lowest and highest binding energy with herbicides were considered as suitable for preparing the environmental biosensors for detecting specific herbicide classes. Arising from the results of theoretical calculations, three mutants were prepared by site-directed mutagenesis and characterized by fluorescence analysis. Their adsorption and selective recognition ability were studied by an equilibrium-adsorption method. The S268C and S264K biomediators showed high sensitivity and resistance, respectively, to both triazine and urea classes of herbicides. When immobilized on a silicon septum, the biomediators were found to be highly stable, remaining so for at least 1-month at room temperature. The fluorescence properties were exploited and a reusable and portable multiarray optical biosensor for environmental monitoring was developed with limits of detection between 0.8 x 10(-11) and 3.0 x 10(-9), depending on the target analyte. In addition, biomediator regeneration without obvious deterioration in performance was demonstrated. PMID:19674888

  5. Growth, structural, optical and electrical study of Na-substituted potassium hydrogen tartrate crystals

    NASA Astrophysics Data System (ADS)

    Mir, F. A.

    2012-02-01

    K1-xNaxHC4H4O6 · H2O (x = 0.3 and 0.7) single crystals have been grown by the gel encapsulation technique. The composition-related structural, optical and electrical properties are investigated. All the crystals have an orthorhombic structure. With the increase of Na content, the transparency of the crystals increases and the band gap values decrease. Good optical transmission of these crystals predicts them to be potential candidates for nonlinear optical applications. From the study on electrical conductivity, a semiconducting behavior is observed for these crystals. Resistivity, activation energy and hoping range are found to decrease with Na doping. DC conductivity behavior observed in these crystals is found to follow a variable-range hopping model. A clear indication of disorder induced in these crystals after Na doping is observed.

  6. Optical study of Sb-S-I glass photonic crystals

    NASA Astrophysics Data System (ADS)

    Starczewska, Anna; Kępińska, Mirosława; Nowak, Marian; Szperlich, Piotr

    2015-12-01

    This work is focused on optical investigations of Sb-S-I glass photonic crystals based on three-dimensional opal template with a closed-packed face centered cubic (fcc) lattice prepared from monodisperse silicon (SiO2) spheres by gravity sedimentation. Three types of photonic structures have been examined: SiO2-opals, opals filled with Sb-S-I glass (direct opals) and Sb-S-I inverted opals obtained after removing SiO2 templates. Optical properties have been investigated by reflectance spectroscopy for wavelengths from 250 nm to 1100 nm. These measurements exhibit Bragg's peaks connected with photonic band gap that is tunable in position and width by varying the diameter of spheres and medium filling the opal. Values of the real parts of refractive index of the Sb-S-I in the fabricated inverted opals nmed[λ ∈ (850-950) nm] = 2.42 ± 0.08 and nmed[λ ∈ (675-750) nm] = 2.39 ± 0.11 have been determined.

  7. Optical coatings on laser crystals for HiPER project

    NASA Astrophysics Data System (ADS)

    Oulehla, Jindrich; Pokorný, Pavel; Lazar, Josef

    2011-12-01

    In this contribution we present a technology for deposition of interference coatings for optical components designed to operate as active media in power pulsed lasers. The aim of the technology is to prepare crystals for lasers for the HiPER project (High Power laser Energy Research facility) which should demonstrate the feasibility of laser driven fusion as a future energy source. Diode pumped solid state lasers (DPSSL) are the most likely option for fusion ignition. The choice of the material for the lasers' active medium is critical. Some of the most important properties include the ability to be antireflection coated to reduce the energy losses and increase the overall efficiency. This contribution deals with some of the materials considered to be candidates for slabs serving as the active medium of the DPSSLs. We tested Yb:YAG and Yb:CaF2 samples. As large amounts of heat need to be dissipated during laser operation, cryogenic cooling is necessary. Appropriate coating materials and techniques need to be chosen. Therefore differences between available coating techniques are investigated in terms of adhesion, enduring of stress from temperature shocks, etc. Coated samples were placed into cryogenic environment in order to simulate conditions similar to those in real life operation. Optical microscopy was used for coating investigation after the conducted experiments.

  8. Optical coatings on laser crystals for HiPER project

    NASA Astrophysics Data System (ADS)

    Oulehla, Jindrich; Pokorný, Pavel; Lazar, Josef

    2011-06-01

    In this contribution we present a technology for deposition of interference coatings for optical components designed to operate as active media in power pulsed lasers. The aim of the technology is to prepare crystals for lasers for the HiPER project (High Power laser Energy Research) which should demonstrate the feasibility of laser driven fusion as a future energy source. Diode pumped solid state lasers (DPSSL) are the most likely option for fusion ignition. The choice of material for the lasers active medium is critical. Some of the most important properties include the ability to be antireflection coated to reduce the energy losses and increase the overall efficiency. This contribution deals with some of the materials considered to be candidates for slabs serving as the active medium of the DPSSLs. We tested Yb:YAG, Yb:CaF2 and Yb:KGW samples. As large amounts of heat need to be dissipated during laser operation, cryogenic cooling is necessary. Appropriate coating materials and techniques need to be chosen. Therefore differences between available coating techniques are investigated in terms of adhesion, enduring of stress resulting from temperature shocks, etc. Coated samples were placed in a specially designed cryogenic apparatus in order to simulate conditions similar to those in real life operation. Optical microscopy and spectrophotometer measurements were used for coating investigation after the conducted experiments.

  9. Ultracompact variable optical attenuator based on photonic crystal waveguide

    NASA Astrophysics Data System (ADS)

    Zhao, Qiang; Cui, Kaiyu; Huang, Yidong

    2011-12-01

    We demonstrated and fabricated a 20μm-long ultra-compact variable optical attenuator based on thermo-optical effect with slow light photonic crystal waveguide (PCWG). In simulation, we optimize the line-defect width and radius/period ratio (r/a) of the PCWG for deep photonic band gap and large slope photonic band edge. An r/a=140nm/410nm W1 PCWG is selected for its -60dB depth and 36dB variable attenuation range when the tunable refractive index change is 0.01. We also study different shapes of micro-heaters for low power consumption and high heat transfer efficiency. A 24.6mW and 75.9% heat transfer efficiency are achieved in a 2μm-wide right-angle-shaped micro-heater. In experiment, A 4.6nm red shift at the cutoff wavelength of the fundamental mode and a 10dB tunable attenuation range are achieved through tuning the temperature of the W1 PCWG by an 4.7μm-wide aluminum micro-heater with a maximum power consumption as low as 30.7mW.

  10. Carbon nanotube biosensors

    PubMed Central

    Tîlmaciu, Carmen-Mihaela; Morris, May C.

    2015-01-01

    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular, carbon nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical, and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites, or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we describe their structural and physical properties, functionalization and cellular uptake, biocompatibility, and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers. PMID:26579509

  11. Carbon Nanotube Biosensors

    NASA Astrophysics Data System (ADS)

    Tilmaciu, Carmen-Mihaela; Morris, May

    2015-10-01

    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular Carbon Nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we will describe their structural and physical properties, discuss functionalization and cellular uptake, biocompatibility and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers.

  12. DNA nanotechnology-enabled biosensors.

    PubMed

    Chao, Jie; Zhu, Dan; Zhang, Yinan; Wang, Lianhui; Fan, Chunhai

    2016-02-15

    Biosensors employ biological molecules to recognize the target and utilize output elements which can translate the biorecognition event into electrical, optical or mass-sensitive signals to determine the quantities of the target. DNA-based biosensors, as a sub-field to biosensor, utilize DNA strands with short oligonucleotides as probes for target recognition. Although DNA-based biosensors have offered a promising alternative for fast, simple and cheap detection of target molecules, there still exist key challenges including poor stability and reproducibility that hinder their competition with the current gold standard for DNA assays. By exploiting the self-recognition properties of DNA molecules, researchers have dedicated to make versatile DNA nanostructures in a highly rigid, controllable and functionalized manner, which offers unprecedented opportunities for developing DNA-based biosensors. In this review, we will briefly introduce the recent advances on design and fabrication of static and dynamic DNA nanostructures, and summarize their applications for fabrication and functionalization of DNA-based biosensors. PMID:26212206

  13. Growth, Structural And Optical Studies On Bis L-alanine Lithium Chloride (BLALC) Single Crystal

    NASA Astrophysics Data System (ADS)

    Rose, A. S. J. Lucia; Selvarajan, P.; Perumal, S.

    2011-10-01

    Bis L-alanine Lithium Chloride (BLALC) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 15 x 9 x 4 mm3 have been obtained in 28 days. The grown crystals were colourless and transparent. Single crystal X-ray diffraction (XRD) study showed that BLALC belongs to orthorhombic system with a non-centro-symmetric space group P212121. The crystallinity of BLALC crystal was confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. The functional groups of the grown crystals have been identified by FTIR studies. UV-visible transmittance spectrum was recorded to study the optical transparency of BLALC crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique.

  14. Structural, optical, mechanical and dielectric studies of pure and doped L-Prolinium Trichloroacetate single crystals

    NASA Astrophysics Data System (ADS)

    Renuka, N.; Ramesh Babu, R.; Vijayan, N.; Vasanthakumar, Geetha; Krishna, Anuj; Ramamurthi, K.

    2015-02-01

    In the present work, pure and metal substituted L-Prolinium trichloroacetate (LPTCA) single crystals were grown by slow evaporation method. The grown crystals were subjected to single crystal X-ray diffraction (XRD), powder X-ray diffraction, FTIR, UV-Visible-NIR, hardness, photoluminescence and dielectric studies. The dopant concentration in the crystals was measured by inductively coupled plasma (ICP) analysis. Single crystal X-ray diffraction studies of the pure and metal substituted LPTCA revealed that the grown crystals belong to the trigonal system. Ni2+ and Co2+ doping slightly altered the lattice parameters of LPTCA without affecting the basic structure of the crystal. FTIR spectral analysis confirms the presence of various functional groups in the grown crystals. The mechanical behavior of pure and doped crystals was analyzed by Vickers's microhardness test. The optical transmittance, dielectric and photoluminescence properties of the pure and doped crystals were analyzed.

  15. Photonic crystal planar waveguide devices exploiting the thermo-optic effect (Keynote Paper)

    NASA Astrophysics Data System (ADS)

    De La Rue, Richard M.; Chong, Harold; Camargo, Edilson; Ciminelli, Caterina; Armenise, Mario

    2005-07-01

    Photonic crystal devices are now being produced for a variety of functions-and the need to provide thermal control of the behaviour suggests the use of thermo-optic effects. It has emerged that thermo-optic effects can provide useful modulation, switching and tuning capability. Future trends indicate fast, low-power, thermo-optically operated photonic crystal and photonic wire devices-and the possibility of simultaneous athermal characteristics.

  16. Generation of optical crystals and quasicrystal beams: Kaleidoscopic patterns and phase singularity

    SciTech Connect

    Chen, Y. F.; Liang, H. C.; Lin, Y. C.; Tzeng, Y. S.; Su, K. W.; Huang, K. F.

    2011-05-15

    We explore the feasibility of the generation of pseudonondiffracting optical beams related to crystal and quasicrystal structures. It is experimentally confirmed that optical crystal and quasicrystal beams can be remarkably generated with a collimated light to illuminate a high-precision mask with multiple apertures regularly distributed on a ring. We also found that exotic kaleidoscopic patterns can be exhibited with the high-order quasicrystal beams. More importantly, the structures of phase singularities in optical quasicrystal beams are manifested.

  17. Single crystal growth of Sr2TiMnO6 by optical floating zone technique

    NASA Astrophysics Data System (ADS)

    Murugesan, G.; Nithya, R.; Kalainathan, S.; Das, Amitabh

    2016-05-01

    Single crystals of Sr2TiMnO6 were grown by optical floating zone technique. Powder X-ray diffraction studies confirmed the single phase nature of the grown crystal. Laue diffraction studies proved the quality of the grown crystal. Neutron diffraction showed no magnetic ordering down to 6K. Impedance studies showed temperature dependant relaxation which is due to the presence of oxygen vacancies in the grown crystal.

  18. Growth and characterization of nonlinear optical single crystal: Nicotinic L-tartaric

    SciTech Connect

    Sheelarani, V.; Shanthi, J.

    2015-06-24

    Nonlinear optical single crystals were grown from Nicotinic and L-Tartaric acid by slow evaporation technique at room temperature. Structure of the grown crystal was confirmed by single crystal X-ray diffraction studies, The crystallinity of the Nicotinic L-Tartaric (NLT) crystals was confirmed from the powder XRD pattern. The transparent range and cut off wavelength of the grown crystal was studied by the UV–Vis spectroscopic analysis.The thermal stability of the crystal was studied by TG-DTA. The second harmonic generation (SHG) efficiency of NLT was confirmed by Kurtz Perry technique.

  19. Calculation of optical second-harmonic susceptibilities and optical activity for crystals

    SciTech Connect

    Levine, Z.H.

    1994-12-31

    A new generation of nearly first-principles calculations predicts both the linear and second-harmonic susceptibilities for a variety of insulating crystals, including GaAs, GaP, AlAs, AlP, Se, {alpha}-quartz, and c-urea. The results are typically in agreement with experimental measurements. The calculations have been extended to optical activity, with somewhat less success to date. The theory, based on a simple self-energy correction to the local density approximation, and results are reviewed herein.

  20. Glycerol capped PbS/CdS core/shell nanoparticles at different molar ratio and its application in biosensors: An optical properties study

    NASA Astrophysics Data System (ADS)

    Das, D.; Hussain, A. M. P.

    2016-05-01

    Glycerol capped PbS/CdS core/shell type nanoparticles fabricated with two different molar ratios are characterized for study of structural and optical properties. The X-ray diffraction (XRD) pattern exhibits cubic phased polycrystalline nanocrystals. The calculated grain sizes from Williamson-Hall plot were found to be around 6 nm with increased strain. HRTEM investigation confirms the formation of core/shell nanostructures and the sizes of the particles were found to be around 7 nm which is in good agreement with the results of the W-H plot. An increase of band gap with the decrease in precursor concentration is confirmed from the blue shift in the absorption spectra and also from Tauc plot. A clear blue shifted intense emission is observed in the photoluminescence spectra with decrease in particle size. Intense luminescence from the core/shell nanostructure may be applied in bio labelling and biosensors.

  1. Self-Action of Light Fields in Waveguide Photon Structures Based on Electro-Optic Crystals

    NASA Astrophysics Data System (ADS)

    Shandarov, V. M.

    2016-02-01

    Special features of spatial self-action of light fields in nonlinear optical photonic waveguide structures formed in strontium barium niobate and lithium niobate electro-optic crystals are discussed. The main methods of forming such structures including photorefractive waveguide elements and systems are briefly considered. The formation of spatial optical solitons in planar waveguides based on lithium niobate and strontium barium niobate crystals as well as in one-dimensional photonic lattices in lithium niobate is demonstrated experimentally for light beams of microwatt power. In regimes of spatial optical solitons, channel optical waveguides are formed not only in the planar waveguides, but also in the volume of photorefractive lithium niobate.

  2. Observation of optical limiting and backscattering of nanosecond laser pulses in liquid-crystal fibers.

    PubMed

    Khoo, I C; Li, H; Lopresti, P G; Liang, Y

    1994-04-15

    We report the recent observation of nonlinear-optical phenomena occurring in isotropic liquid-crystal-cored optical fibers, including passive all-optical self-limiting effects, stimulated backscattering, and phase conjugation. These processes occur at relatively low thresholds and short fiber lengths. PMID:19844362

  3. Slotted photonic crystal sensors.

    PubMed

    Scullion, Mark G; Krauss, Thomas F; Di Falco, Andrea

    2013-01-01

    Optical biosensors are increasingly being considered for lab-on-a-chip applications due to their benefits such as small size, biocompatibility, passive behaviour and lack of the need for fluorescent labels. The light guiding mechanisms used by many of them results in poor overlap of the optical field with the target molecules, reducing the maximum sensitivity achievable. This review article presents a new platform for optical biosensors, namely slotted photonic crystals, which provide higher sensitivities due to their ability to confine, spatially and temporally, the optical mode peak within the analyte itself. Loss measurements showed values comparable to standard photonic crystals, confirming their ability to be used in real devices. A novel resonant coupler was designed, simulated, and experimentally tested, and was found to perform better than other solutions within the literature. Combining with cavities, microfluidics and biological functionalization allowed proof-of-principle demonstrations of protein binding to be carried out. Higher sensitivities were observed in smaller structures than possible with most competing devices reported in the literature. This body of work presents slotted photonic crystals as a realistic platform for complete on-chip biosensing; addressing key design, performance and application issues, whilst also opening up exciting new ideas for future study. PMID:23503295

  4. Slotted Photonic Crystal Sensors

    PubMed Central

    Scullion, Mark G.; Krauss, Thomas F.; Di Falco, Andrea

    2013-01-01

    Optical biosensors are increasingly being considered for lab-on-a-chip applications due to their benefits such as small size, biocompatibility, passive behaviour and lack of the need for fluorescent labels. The light guiding mechanisms used by many of them results in poor overlap of the optical field with the target molecules, reducing the maximum sensitivity achievable. This review article presents a new platform for optical biosensors, namely slotted photonic crystals, which provide higher sensitivities due to their ability to confine, spatially and temporally, the optical mode peak within the analyte itself. Loss measurements showed values comparable to standard photonic crystals, confirming their ability to be used in real devices. A novel resonant coupler was designed, simulated, and experimentally tested, and was found to perform better than other solutions within the literature. Combining with cavities, microfluidics and biological functionalization allowed proof-of-principle demonstrations of protein binding to be carried out. Higher sensitivities were observed in smaller structures than possible with most competing devices reported in the literature. This body of work presents slotted photonic crystals as a realistic platform for complete on-chip biosensing; addressing key design, performance and application issues, whilst also opening up exciting new ideas for future study. PMID:23503295

  5. SINGLE-CRYSTAL SAPPHIRE OPTICAL FIBER SENSOR INSTRUMENTATION

    SciTech Connect

    A. Wang; G. Pickrell; R. May

    2002-09-10

    Accurate measurement of temperature is essential for the safe and efficient operation and control of a wide range of industrial processes. Appropriate techniques and instrumentation are needed depending on the temperature measurement requirements in different industrial processes and working environments. Harsh environments are common in many industrial applications. These harsh environments may involve extreme physical conditions, such as high-temperature, high-pressure, corrosive agents, toxicity, strong electromagnetic interference, and high-energy radiation exposure. Due to these severe environmental conditions, conventional temperature sensors are often difficult to apply. This situation has opened a new but challenging opportunity for the sensor society to provide robust, high-performance, and cost-effective temperature sensors capable of operating in those harsh environments. The focus of this research program has been to develop a temperature measurement system for temperature measurements in the primary and secondary stages of slagging gasifiers. For this application the temperature measurement system must be able to withstand the extremely harsh environment posed by the high temperatures and corrosive agents present in these systems. Real-time, accurate and reliable monitoring of temperature for the coal gasification process is important to realize the full economic potential of these gasification systems. Long life and stability of operation in the high temperature environment is essential for the temperature measurement system to ensure the continuous running of the coal gasification system over the long term. In this high temperature and chemically corrosive environment, rather limited high temperature measurement techniques such as high temperature thermocouples and optical/acoustic pyrometers are available, each with their own limitations. In this research program, five different temperature sensing schemes based on the single crystal sapphire

  6. Nonlinear optical studies of liquid crystals and polymers

    NASA Astrophysics Data System (ADS)

    Hong, Seok-Cheol

    Polymers are indispensable in our life. A life is a continuous event maintained by many complex processes in which biological polymers participate. It also gets help from a variety of natural and synthetic polymers with useful functions. Such functions depend on the chemical and conformational structures of polymers and often largely on the surface structures and properties of polymers. We used second order nonlinear optical techniques (sum frequency vibrational spectroscopy (SFVS) and second harmonic generation (SHG)) to obtain structural information on polymers. We also studied liquid crystal molecules deposited on polymer surfaces. The first part of the thesis is aimed at understanding liquid crystal (LC) alignment on rubbed polymer surfaces by determining the molecular orientations of LC adsorbates and surface polymer chains. The alignment of LCs by rubbed polymers is not only of fundamental interest but also of practical importance because it is a technique enabling production of commercial liquid crystal displays. We observed that rubbing induces alignment of surface polymer chains along the rubbing direction, and there is a strong correlation between the molecular orientations of LC adsorbates and the surface chains of rubbed polymers such as polyvinyl alcohol (PVA) and polyimide (6FDA-6CBO). The latter revealed a relatively large but negative pretilt angle, which is highly unusual. On a rubbed polystyrene (PS) surface, we found that the phenyl side groups of PS are oriented perpendicularly to the rubbing direction at the surface, rendering an LC alignment also perpendicular to the rubbing direction. The second part of the thesis is our discovery of rubbing-induced polar ordering on nylon 11 surfaces. Nylon 11 is known to be ferroelectric. We found that mechanical rubbing can induce strong ferroelectric polarization on an initially amorphous film of nylon 11. The surface chains of rubbed nylon 11 are aligned along the rubbing direction while the induced

  7. Synthesis, growth and optical properties of an efficient nonlinear optical single crystal: L-alanine DL-malic acid

    NASA Astrophysics Data System (ADS)

    Kirubagaran, R.; Madhavan, J.

    2015-02-01

    Single crystals of L-alanine DL-malic acid (LADLMA) have been grown from aqueous solution by slow-cooling technique. Powder X-ray diffraction studies reveal the structure of the crystal to be orthorhombic. The nonlinear optical conversion efficiency test was carried out for the grown crystals using the Kurtz powder technique. The third order nonlinear refractive index and the nonlinear absorption coefficient where evaluated by Z-scan measurements. As the material have a negative refractive index it could be used in the protection of optical sensors such as night vision devices.

  8. A living cell quartz crystal microbalance biosensor for continuous monitoring of cytotoxic responses of macrophages to single-walled carbon nanotubes

    PubMed Central

    2011-01-01

    Background Numerous engineered nanomaterials (ENMs) exist and new ENMs are being developed. A challenge to nanotoxicology and environmental health and safety is evaluating toxicity of ENMs before they become widely utilized. Cellular assays remain the predominant test platform yet these methods are limited by using discrete time endpoints and reliance on organic dyes, vulnerable to interference from ENMs. Label-free, continuous, rapid response systems with biologically meaningful endpoints are needed. We have developed a device to detect and monitor in real time responses of living cells to ENMs. The device, a living cell quartz crystal microbalance biosensor (QCMB), uses macrophages adherent to a quartz crystal. The communal response of macrophages to treatments is monitored continuously as changes in crystal oscillation frequency (Δf). We report the ability of this QCMB to distinguish benign from toxic exposures and reveal unique kinetic information about cellular responses to varying doses of single-walled carbon nanotubes (SWCNTs). Results We analyzed macrophage responses to additions of Zymosan A, polystyrene beads (PBs) (benign substances) or SWCNT (3-150 μg/ml) in the QCMB over 18 hrs. In parallel, toxicity was monitored over 24/48 hrs using conventional viability assays and histological stains to detect apoptosis. In the QCMB, a stable unchanging oscillation frequency occurred when cells alone, Zymosan A alone, PBs alone or SWCNTs without cells at the highest dose alone were used. With living cells in the QCMB, when Zymosan A, PBs or SWCNTs were added, a significant decrease in frequency occurred from 1-6 hrs. For SWCNTs, this Δf was dose-dependent. From 6-18 hrs, benign substances or low dose SWCNT (3-30 μg/ml) treatments showed a reversal of the decrease of oscillation frequency, returning to or exceeding pre-treatment levels. Cell recovery was confirmed in conventional assays. The lag time to see the Δf reversal in QCMB plots was linearly SWCNT

  9. Fabrication of optical element from unidirectional grown imidazole-imidazolium picrate monohydrate (IIP) organic crystals for nonlinear optical applications

    NASA Astrophysics Data System (ADS)

    Vivek, P.; Murugakoothan, P.

    2014-12-01

    Nonlinear optical bulk single crystal of Imidazole-imidazolium picrate monohydrate (IIP) has been grown by Sankaranarayanan-Ramasamy (SR) method using acetonitrile as solvent. First time we report the bulk growth of IIP crystal by SR method. The transparent IIP single crystal of maximum diameter 21 mm and length 46 mm was obtained by employing SR method. The grown crystal was subjected to high resolution X-ray diffraction, UV-vis-NIR transmittance, refractive index, hardness, dielectric and laser damage threshold studies. The crystalline perfection of the grown crystal was analyzed using HRXRD. Cut off wavelength and optical transmission window of the crystal was assessed by UV-vis-NIR and the refractive index of the crystal was found. The mechanical property of the crystal was estimated by Vicker's hardness test. The dielectric property of the crystal was measured as a function of frequency. The laser damage threshold value was determined. The particle size dependent second harmonic generation efficiency for IIP was evaluated with standard reference material potassium dihydrogen phosphate (KDP) by Kurtz-Perry powder method using Nd:YAG laser, which established the existence of phase matching. The second harmonic generation (SHG) of IIP crystal was investigated by the SHG Maker fringes technique. The mechanism of growth is revealed by carrying out chemical etching using acetonitrile as etchant.

  10. Growth and birefringence studies of semi organic non-linear optical LHB single crystal

    NASA Astrophysics Data System (ADS)

    Jayaramakrishnan, V.; Prasanyaa, T.; Haris, M.; Bhoopathi, G.

    2015-02-01

    In the last few decades nonlinear optical materials are getting attention in the field of optical data storage, telecommunication, second harmonic generation (SHG) and optical signal processing, etc. In the present work we are reporting the single crystal growth of L-Histidine with hydro-bromic acid. The L-Histidine bromide (LHB) single crystals have been harvested from the solution in a span of 34 days by adopting slow cooling solution growth technique. The grown crystals have been subjected to powder X-ray diffraction studies to identify the cell parameters and structure. The crystalline perfection has been defined by rocking curve (HRXRD) analysis. Optical transmission spectra reveal the optical properties of the grown crystals. The Modified channel spectrum (MCS) method has been adopted for the study of spectral dependence of linear birefringence over the wavelength range 480-620 nm. The second harmonic generation efficiency was tested by using Kurtz and Perry method, keeping KDP as reference.

  11. Boundary effects in finite size plasmonic crystals: focusing and routing of plasmonic beams for optical communications

    NASA Astrophysics Data System (ADS)

    Benetou, M. I.; Bouillard, J.-S.; Segovia, P.; Dickson, W.; Thomsen, B. C.; Bayvel, P.; Zayats, A. V.

    2015-11-01

    Plasmonic crystals, which consist of periodic arrangements of surface features at a metal-dielectric interface, allow the manipulation of optical information in the form of surface plasmon polaritons. Here we investigate the excitation and propagation of plasmonic beams in and around finite size plasmonic crystals at telecom wavelengths, highlighting the effects of the crystal boundary shape and illumination conditions. Significant differences in broad plasmonic beam generation by crystals of different shapes are demonstrated, while for narrow beams, the propagation from a crystal onto the smooth metal film is less sensitive to the crystal boundary shape. We show that by controlling the boundary shape, the size and the excitation beam parameters, directional control of propagating plasmonic modes and their behaviour such as angular beam splitting, focusing power and beam width can be efficiently achieved. This provides a promising route for robust and alignment-independent integration of plasmonic crystals with optical communication components.

  12. Boundary effects in finite size plasmonic crystals: focusing and routing of plasmonic beams for optical communications.

    PubMed

    Benetou, M I; Bouillard, J-S; Segovia, P; Dickson, W; Thomsen, B C; Bayvel, P; Zayats, A V

    2015-11-01

    Plasmonic crystals, which consist of periodic arrangements of surface features at a metal-dielectric interface, allow the manipulation of optical information in the form of surface plasmon polaritons. Here we investigate the excitation and propagation of plasmonic beams in and around finite size plasmonic crystals at telecom wavelengths, highlighting the effects of the crystal boundary shape and illumination conditions. Significant differences in broad plasmonic beam generation by crystals of different shapes are demonstrated, while for narrow beams, the propagation from a crystal onto the smooth metal film is less sensitive to the crystal boundary shape. We show that by controlling the boundary shape, the size and the excitation beam parameters, directional control of propagating plasmonic modes and their behaviour such as angular beam splitting, focusing power and beam width can be efficiently achieved. This provides a promising route for robust and alignment-independent integration of plasmonic crystals with optical communication components. PMID:26469205

  13. Optical electric-field sensor based on angular optical bias using single β-BaB2O4 crystal.

    PubMed

    Li, Changsheng; Shen, Xiaoli; Zeng, Rong

    2013-11-01

    A novel optical electric-field sensor is proposed and demonstrated in experiment by use of a single beta barium borate (β-BaB2O4, BBO) crystal. The optical sensing unit is only composed of one BBO crystal and two polarizers. An optical phase bias of 0.5π is provided by using natural birefringence in the BBO crystal itself. A small angle (e.g., 0.6°) between the sensing light beam and principal axis of the crystal is required in order to produce the above optical bias. Thus the BBO crystal is used as the electric-field-sensing element and quarter waveplate. The ac electric field in the range of (1.4-703.2) kV/m has been measured with measurement sensitivity of 1.39 mV/(kV/m) and nonlinear error of 0.6%. Compared with lithium niobate crystal used as an electric-field sensor, main advantages of the BBO crystal include higher measurement sensitivity, compact configuration, and no ferroelectric ringing effect. PMID:24216661

  14. Review on recent progress of three-dimensional optical photonic crystal

    SciTech Connect

    Hsieh, Mei-Li; Kuang, Ping; Bur, James A.; Lin, Shawn-Yu; John, Sajeev

    2014-03-31

    Over the past two decades, the field of photonic-crystals has become one of the most influential realms of contemporary optics. In this paper, we will review two recent experimental progresses in three-dimensional photonic-crystal operating in optical wavelengths. The first is the observation of anomalous light-refraction, an acutely negative refraction, in a 3D photonic-crystal for light trapping, guiding and near-unity absorption. The second is the observation of quasi-coherent thermal emission from an all-metallic 3D photonic-crystal at elevated temperatures.

  15. Appearance of singularities of optical fields under torsion of crystals containing threefold symmetry axes.

    PubMed

    Skab, Ihor; Vasylkiv, Yurij; Zapeka, Bohdan; Savaryn, Viktoriya; Vlokh, Rostyslav

    2011-07-01

    We present an analysis of the effect of torsion stresses on the spatial distribution of optical birefringence in crystals of different point symmetry groups. The symmetry requirements needed so that the optical beam carries dislocations of the phase front are evaluated for the case when the crystals are twisted and the beam closely corresponds to a plane wave. It is shown that the torsion stresses can produce screw-edge, pure screw, or pure edge dislocations of the phase front in the crystals belonging to cubic and trigonal systems. The conditions for appearance of canonical and noncanonical vortices in the conditions of crystal torsion are analyzed. PMID:21734730

  16. Organic Single-Crystal Light-Emitting Transistor Coupling with Optical Feedback Resonators

    PubMed Central

    Bisri, Satria Zulkarnaen; Sawabe, Kosuke; Imakawa, Masaki; Maruyama, Kenichi; Yamao, Takeshi; Hotta, Shu; Iwasa, Yoshihiro; Takenobu, Taishi

    2012-01-01

    Organic light-emitting transistors (OLETs) are of great research interest because they combine the advantage of the active channel of a transistor that can control the luminescence of an in-situ light-emitting diode in the same device. Here we report a novel single-crystal OLET (SCLET) that is coupled with single crystal optical feedback resonators. The combination of single-crystal waveguides with native Fabry-Perot cavities, formed by parallel crystal edges, drastically lowers the threshold energy for spectral narrowing and non-linear intensity enhancement. We apply this structure to SCLETs and demonstrate the first fabrication of a SCLET with the optical feedback resonators. PMID:23248748

  17. Liquid crystals as optical amplifiers for bacterial detection.

    PubMed

    Zafiu, C; Hussain, Z; Küpcü, S; Masutani, A; Kilickiran, P; Sinner, E-K

    2016-06-15

    Interactions of bacteria with target molecules (e.g. antibiotics) or other microorganisms are of growing interest. The first barrier for targeting gram-negative bacteria is layer of a Lipopolysaccharides (LPS). Liquid crystal (LC) based sensors covered with LPS monolayers, as presented in this study, offer a simple model to study and make use of this type of interface for detection and screening. This work describes in detail the production and application of such sensors based on three different LPS that have been investigated regarding their potential to serve as sensing layer to detect bacteria. The LPS O127:B8 in combination with a LC based sensor was identified to be most useful as biomimetic sensing surface. This LPS/LC combination interacts with three different bacteria species, one gram-positive and two gram-negative species, allowing the detection of bacterial presence regardless from their viability. It could be shown that even very low bacterial cell numbers (minimum 500 cell ml(-1)) could be detected within minutes (maximum 15 min). The readout mechanism is the adsorption of bacterial entities on surface bond LPS molecules with the LC serving as an optical amplifier. PMID:26827146

  18. Optical detection and characterization of ice crystals in LACIS

    NASA Astrophysics Data System (ADS)

    Kiselev, Alexei; Clauß, Tina; Niedermeier, Dennis; Hartmann, Susan; Wex, Heike; Stratmann, Frank

    2010-05-01

    Tropospheric ice and mixed phase clouds are an integral part of the earth system and their microphysical and radiative properties are strongly coupled e.g. through the complexities of the ice nucleation process. Therefore the investigation of influences of different aerosol particles which act as ice nuclei (IN) on the freezing behaviour of cloud droplets is important and still poses unresolved questions. The Leipzig Aerosol and Cloud Interaction Simulator (LACIS) is used to investigate the IN activity of different natural and artificial aerosol particles (mineral dust, soot etc.) in heterogeneous freezing processes (immersion or deposition freezing). A critical part of LACIS is the particle detection system allowing for size-resolved counting of activated seed particles and discrimination between ice crystals and water droplets. Recently, two instruments have been developed to provide these measurements at the LACIS facility. The Thermally-stabilized Optical Particle Spectrometer (TOPS) is measuring the particle size based on the intensity of light scattered by individual particles into a near-forward (15° to 45°) direction. Two symmetrical forward scattering channels allow for optical determination of the sensing volume, thus reducing the coincidence counting error and the edge zone effect. The backscatter channel (162° to 176°) equipped with a rotatable cross polarizer allows for establishing the change in linear polarization state of the scattered light. The backscatter elevation angle is limited so that the linear depolarization of light scattered by spherical particles of arbitrary size is zero. Any detectable signal in the depolarization channel can be therefore attributed to non-spherical particles (ice crystals). With consideration of the signal in the backscatter channel the separate counting of water drops and ice particle is possible. The Leipzig Ice Scattering Apparatus (LISA) is a modified version of the Small Ice Detector (SID3), developed at the

  19. Crystal growth and optical characteristics of beryllium-free polyphosphate, KLa(PO3)4, a possible deep-ultraviolet nonlinear optical crystal

    NASA Astrophysics Data System (ADS)

    Shan, Pai; Sun, Tongqing; Chen, Hong; Liu, Hongde; Chen, Shaolin; Liu, Xuanwen; Kong, Yongfa; Xu, Jingjun

    2016-04-01

    Deep-ultraviolet nonlinear optical crystals are of great importance as key materials in generating coherent light with wavelength below 200 nm through cascaded frequency conversion of solid-state lasers. However, the solely usable crystal in practice, KBe2BO3F2 (KBBF), is still commercially unavailable because of the high toxicity of beryllium-containing and the extreme difficulty of crystal growth. Here, we report the crystal growth and characteristics of an beryllium-free polyphosphate, KLa(PO3)4. Centimeter-sized single crystals have been easily obtained by the flux method and slow-cooling technique. The second-harmonic generation efficiency of KLa(PO3)4 powder is 0.7 times that of KH2PO4; moreover, the KLa(PO3)4 crystal is phase-matchable. Remarkably, the KLa(PO3)4 crystal exhibits an absorption edge of 162 nm, which is the shortest among phase-matchable phosphates so far. These attributes make KLa(PO3)4 a possible deep-ultraviolet nonlinear optical crystal. An analysis of the dipole moments of the polyhedra and theoretical calculations by density functional theory were made to elucidate the structure-properties relationships of KLa(PO3)4.

  20. Crystal growth and optical characteristics of beryllium-free polyphosphate, KLa(PO3)4, a possible deep-ultraviolet nonlinear optical crystal.

    PubMed

    Shan, Pai; Sun, Tongqing; Chen, Hong; Liu, Hongde; Chen, Shaolin; Liu, Xuanwen; Kong, Yongfa; Xu, Jingjun

    2016-01-01

    Deep-ultraviolet nonlinear optical crystals are of great importance as key materials in generating coherent light with wavelength below 200 nm through cascaded frequency conversion of solid-state lasers. However, the solely usable crystal in practice, KBe2BO3F2 (KBBF), is still commercially unavailable because of the high toxicity of beryllium-containing and the extreme difficulty of crystal growth. Here, we report the crystal growth and characteristics of an beryllium-free polyphosphate, KLa(PO3)4. Centimeter-sized single crystals have been easily obtained by the flux method and slow-cooling technique. The second-harmonic generation efficiency of KLa(PO3)4 powder is 0.7 times that of KH2PO4; moreover, the KLa(PO3)4 crystal is phase-matchable. Remarkably, the KLa(PO3)4 crystal exhibits an absorption edge of 162 nm, which is the shortest among phase-matchable phosphates so far. These attributes make KLa(PO3)4 a possible deep-ultraviolet nonlinear optical crystal. An analysis of the dipole moments of the polyhedra and theoretical calculations by density functional theory were made to elucidate the structure-properties relationships of KLa(PO3)4. PMID:27126353