Science.gov

Sample records for micro structures sensors

  1. Micro- and nano-structure based oligonucleotide sensors.

    PubMed

    Ferrier, David C; Shaver, Michael P; Hands, Philip J W

    2015-06-15

    This paper presents a review of micro- and nano-structure based oligonucleotide detection and quantification techniques. The characteristics of such devices make them very attractive for Point-of-Care or On-Site-Testing biosensing applications. Their small scale means that they can be robust and portable, their compatibility with modern CMOS electronics means that they can easily be incorporated into hand-held devices and their suitability for mass production means that, out of the different approaches to oligonucleotide detection, they are the most suitable for commercialisation. This review discusses the advantages of micro- and nano-structure based sensors and covers the various oligonucleotide detection techniques that have been developed to date. These include: Bulk Acoustic Wave and Surface Acoustic Wave devices, micro- and nano-cantilever sensors, gene Field Effect Transistors, and nanowire and nanopore based sensors. Oligonucleotide immobilisation techniques are also discussed.

  2. Piezoelectric cellular micro-structured PDMS material for micro-sensors and energy harvesting

    NASA Astrophysics Data System (ADS)

    Kachroudi, A.; Basrour, S.; Rufer, L.; Jomni, F.

    2015-12-01

    This paper reports a novel low-cost fabrication process of a charged cellular microstructured polydimethylsiloxane (PDMS) material referred as piezo-electret or ferro-electret for micro-sensors applications. The dielectric spectra reached on these structures exhibit a high piezoelectric longitudinal coefficient d33 of 350pC/N. A mechanical characterization method proves the reliability of this material for low-frequencies applications around 100Hz.

  3. A novel Michelson Fabry-Perot hybrid interference sensor based on the micro-structured fiber

    NASA Astrophysics Data System (ADS)

    Zhang, Yaxun; Zhang, Yu; Wang, Zhenzhen; Liu, Zhihai; Wei, Yong; Zhao, Enming; Yang, Xinghua; Zhang, Jianzhong; Yang, Jun; Yuan, Libo

    2016-09-01

    We propose and demonstrate a novel Michelson Fabry-Perot hybrid fiber interference sensor. By integrating a Michelson interferometer in a two-core fiber and a Fabry-Perot interferometer in a micro silica-capillary, we produce the Michelson Fabry-Perot hybrid interference sensor. Owing to the structure characteristic of the micro-structured fiber, this hybrid fiber interference sensor can achieve the measurement of the axial strain and radial bending simultaneously. The measurement sensitivity of the axial train is 0.015 nm/με and the measurement sensitivity of the radial bending is 1.393 nm/m-1.

  4. Highly sensitive methane catalytic combustion micro-sensor based on mesoporous structure and nano-catalyst.

    PubMed

    Su, Jiacan; Cao, Liehu; Li, Liang; Wei, Jie; Li, Gengnan; Yuan, Yinyin

    2013-10-21

    In order to get a methane catalytic combustion micro-sensor, two different catalytic systems used in traditional methane catalytic combustion sensors were fabricated into a mesoporous structure and their catalytic activities were investigated. In comparison, the Rh2O3-Al2O3 system can form more a uniform mesoporous structure and has a much higher specific surface area. Even more importantly, it has relatively higher catalytic activity and stability for the methane catalytic combustion reaction. After being coated on a microelectro-mechanical system (MEMS) micro-heater, a catalytic combustion type methane micro-sensor was fabricated. The meso-structured Rh2O3-Al2O3 hybrid based MEMS sensor demonstrated a short T90 response time, relatively high signal output, high enough signal/noise ratio for practical detecting and strong anti-poison properties.

  5. Electrochemical micro sensor

    DOEpatents

    Setter, Joseph R.; Maclay, G. Jordan

    1989-09-12

    A micro-amperometric electrochemical sensor for detecting the presence of a pre-determined species in a fluid material is disclosed. The sensor includes a smooth substrate having a thin coating of solid electrolytic material deposited thereon. The working and counter electrodes are deposited on the surface of the solid electrolytic material and adhere thereto. Electrical leads connect the working and counter electrodes to a potential source and an apparatus for measuring the change in an electrical signal caused by the electrochemical oxidation or reduction of the species. Alternatively, the sensor may be fabricated in a sandwich structure and also may be cylindrical, spherical or other shapes.

  6. Dielectric properties modelling of cellular structures with PDMS for micro-sensor applications

    NASA Astrophysics Data System (ADS)

    Kachroudi, Achraf; Basrour, Skandar; Rufer, Libor; Sylvestre, Alain; Jomni, Fathi

    2015-12-01

    Electro-active polymers are emerging in the fields of actuators and micro-sensors because their good dielectric and mechanical properties makes them suitable for such applications. In this work, we focus on micro-structured (cellular) polymer materials (referred as piezoelectrets or ferroelectrets) that need prior charging to attain piezoelectric behaviour. The development of such applications requires an in-depth knowledge of the intrinsic dielectric properties of such structures and models to enable the accurate prediction of a given micro-structured material’s dielectric properties. Various polymers including polypropylene, polytetrafluoroethylene, fluoroethylenepropylene, cyclo-olefines and poly(ethylene terephthalate) in a cellular form have been studied by researchers over the last fifteen years. However, there is still a lack of information on the intrinsic dielectric properties of the most recently used dielectric polymer (polydimethylsiloxane, PDMS) over wide frequency and temperature ranges. In this work, we shall propose an exhaustive equivalent electrical circuit model and explain how it can be used to predict the micro-structured PDMS complex permittivity versus frequency and temperature. The results obtained from the model were found to be in good agreement with experimental data for various micro-structured PDMS materials. Typically, for micro-sensor applications, the dielectric constant and dielectric losses are key factors which need to be minimized. We have developed a configuration which enables both to be strongly reduced with a reduction of 16% in the dielectric constant of a micro-structured PDMS compared with the bulk material. In addition, the phenomena responsible for dielectric losses variations with frequency and temperature are discussed and correlated with the theoretical model. Our model is thus proved to be a powerful tool for the control of the dielectric properties of micro-structured PDMS material for micro-sensor applications.

  7. Fabrication and Characterization of a-Si Micro and Nano-Gap Structure for Electrochemical Sensor

    NASA Astrophysics Data System (ADS)

    Dhahi, Th. S.; Hashim, U.; Ahmed, N. M.; Ali, Md. Eaqub

    2011-05-01

    The development and application of micro gap for electrochemical sensors and biomolecule detection are reviewed in this article. The preparation methods for micro- and nano-gaps and their properties are discussed along with their advantages in electrochemical sensors and biomolecule detection. Biology and medicine have seen great advances in biosensors and biochips capable of characterizing and quantifying electrochemical sensor. To understand the important relationship between sensibility and nano structure, we introduce the fabrication and characterization of micro- and nano-gap structures for electrochemical sensor. In this paper, two mask designs are proposed. The first is the lateral micro- and nano-gap with aluminum (Al) electrode, and the second mask is for pad Al electrode pattern. Lateral micro-gaps are introduced in the fabrication process using amorphous silicon (a-Si) and Al as an electrode. Conventional ultraviolet lithography technique and dry etching for a-Si layer with wet etching for Al surface processes are used to fabricate the micro- and nano-gaps based on the standard complementary metal-oxide-semiconductor technology and characterization of its conductivity. Electrical characterization is applied using Semiconductor Parameter Analyzer, Spectrum Analyzer, current-voltage (IV)-capacitance-voltage (CV) station for electrical characteristics. Conductivity, resistance, and capacitance tests are performed to characterize and verify the structure of the device, resulting in a small micro-gap as revealed by a further IV curve result showing a current in nano amps. The characteristics of the fabricated gap are close to those of a micro-gap, as verified by the literature.

  8. Fabrication and Structural Design of Micro Pressure Sensors for Tire Pressure Measurement Systems (TPMS).

    PubMed

    Tian, Bian; Zhao, Yulong; Jiang, Zhuangde; Zhang, Ling; Liao, Nansheng; Liu, Yuanhao; Meng, Chao

    2009-01-01

    In this paper we describe the design and testing of a micro piezoresistive pressure sensor for a Tire Pressure Measurement System (TPMS) which has the advantages of a minimized structure, high sensitivity, linearity and accuracy. Through analysis of the stress distribution of the diaphragm using the ANSYS software, a model of the structure was established. The fabrication on a single silicon substrate utilizes the technologies of anisotropic chemical etching and packaging through glass anodic bonding. The performance of this type of piezoresistive sensor, including size, sensitivity, and long-term stability, were investigated. The results indicate that the accuracy is 0.5% FS, therefore this design meets the requirements for a TPMS, and not only has a smaller size and simplicity of preparation, but also has high sensitivity and accuracy.

  9. A micro-force sensor with slotted-quad-beam structure for measuring the friction in MEMS bearings.

    PubMed

    Liu, Huan; Yang, Shuming; Zhao, Yulong; Jiang, Zhuangde; Liu, Yan; Tian, Bian

    2013-09-30

    Presented here is a slotted-quad-beam structure sensor for the measurement of friction in micro bearings. Stress concentration slots are incorporated into a conventional quad-beam structure to improve the sensitivity of force measurements. The performance comparison between the quad-beam structure sensor and the slotted-quad-beam structure sensor are performed by theoretical modeling and finite element (FE) analysis. A hollow stainless steel probe is attached to the mesa of the sensor chip by a tailor-made organic glass fixture. Concerning the overload protection of the fragile beams, a glass wafer is bonded onto the bottom of sensor chip to limit the displacement of the mesa. The calibration of the packaged device is experimentally performed by a tri-dimensional positioning stage, a precision piezoelectric ceramic and an electronic analytical balance, which indicates its favorable sensitivity and overload protection. To verify the potential of the proposed sensor being applied in micro friction measurement, a measurement platform is established. The output of the sensor reflects the friction of bearing resulting from dry friction and solid lubrication. The results accord with the theoretical modeling and demonstrate that the sensor has the potential application in measuring the micro friction force under stable stage in MEMS machines.

  10. A Micro Bubble Structure Based Fabry–Perot Optical Fiber Strain Sensor with High Sensitivity and Low-Cost Characteristics

    PubMed Central

    Yan, Lu; Gui, Zhiguo; Wang, Guanjun; An, Yongquan; Gu, Jinyu; Zhang, Meiqin; Liu, Xinglin; Wang, Zhibin; Wang, Gao; Jia, Pinggang

    2017-01-01

    A high-sensitivity, low-cost, ultrathin, hollow fiber micro bubble structure was proposed; such a bubble can be used to develop a high-sensitivity strain sensor based on a Fabry–Perot interferometer (FPI). The micro bubble is fabricated at the fiber tip by splicing a glass tube to a single mode fiber (SMF) and then the glass tube is filled with gas in order to expand and form a micro bubble. The sensitivity of the strain sensor with a cavity length of about 155 μm and a bubble wall thickness of about 6 μm was measured to be up to 8.14 pm/με. PMID:28282960

  11. Micro sun sensor

    NASA Technical Reports Server (NTRS)

    Liebe, C. C.; Mobasser, S.; Wrigley, C. J.; Bae, Y.; Howard, A.; Schroeder, J.

    2002-01-01

    A new generation of sun sensors is emerging. These sun sensors utilize an imaging detector and the sun sensor determines the sun angles based on an image of fringes or centroids on the detector plane. Typically determines the sun angle in two axes.

  12. Micro-Structured Sapphire Fiber Sensors for Simultaneous Measurements of High-T and Dynamic Gas Pressure in Harsh Environments

    SciTech Connect

    Xiao, Hai; Tsai, Hai-Lung; Dong, Junhang

    2014-09-30

    This is the final report for the program “Micro-Structured Sapphire Fiber Sensors for Simultaneous Measurements of High Temperature and Dynamic Gas Pressure in Harsh Environments”, funded by NETL, and performed by Missouri University of Science and Technology, Clemson University and University of Cincinnati from October 1, 2009 to September 30, 2014. Securing a sustainable energy economy by developing affordable and clean energy from coal and other fossil fuels is a central element to the mission of The U.S. Department of Energy’s (DOE) National Energy Technology Laboratory (NETL). To further this mission, NETL funds research and development of novel sensor technologies that can function under the extreme operating conditions often found in advanced power systems. The main objective of this research program is to conduct fundamental and applied research that will lead to successful development and demonstration of robust, multiplexed, microstructured silica and single-crystal sapphire fiber sensors to be deployed into the hot zones of advanced power and fuel systems for simultaneous measurements of high temperature and gas pressure. The specific objectives of this research program include: 1) Design, fabrication and demonstration of multiplexed, robust silica and sapphire fiber temperature and dynamic gas pressure sensors that can survive and maintain fully operational in high-temperature harsh environments. 2) Development and demonstration of a novel method to demodulate the multiplexed interferograms for simultaneous measurements of temperature and gas pressure in harsh environments. 3) Development and demonstration of novel sapphire fiber cladding and low numerical aperture (NA) excitation techniques to assure high signal integrity and sensor robustness.

  13. Chemical micro-sensor

    DOEpatents

    Ruggiero, Anthony J.

    2005-05-03

    An integrated optical capillary electrophoresis system for analyzing an analyte. A modulated optical pump beam impinges on an capillary containing the analyte/buffer solution which is separated by electrophoresis. The thermally-induced change in the index of refraction of light in said electrophoresis capillary is monitored using an integrated micro-interferometer. The interferometer includes a first interferometer arm intersecting the electrophoresis capillary proximate the excitation beam and a second, reference interferometer arm. Changes in index of refraction in the analyte measured by interrogating the interferometer state using white light interferometry and a phase-generated carrier demodulation technique. Background thermo-optical activity in the buffer solution is cancelled by splitting the pump beam and exciting pure buffer solution in a second section of capillary where it crosses the reference arm of the interferometer.

  14. Self-assembled micro-structured sensors for food safety in paper based food packaging.

    PubMed

    Hakovirta, M; Aksoy, B; Hakovirta, J

    2015-08-01

    Natural self-assembled microstructured particles (diatomaceous earth) were used to develop a gas sensor paper with detection mechanism based on visible and distinct color changes of the sensor paper when exposed to volatile basic nitrogen compounds. The coating formulation for paper was prepared by applying diatomites, polyvinyl alcohol (PVOH), and pH sensitive dyes on acidic paper substrate. The surface coating was designed to allow a maximum gas flow through the diatomite sensors. The produced sensor paper was tested for sensitivity using different ammonia concentrations and we observed a sensitivity lower limit at 63 ppm. As a comparison, the results show comparable sensitivity levels to carbon nanotube based sensor technologies reported in literature.

  15. Morphology tailoring of nano/micro-structured conductive polymers, composites and their applications in chemical sensors.

    PubMed

    Ma, Xingfa; Gao, Mingjun; He, Xiaochun; Li, Guang

    2010-11-01

    Conductive polymer is one of the important multi-functional materials. It has many applications in light-emitting diodes, chemical sensors, biosensors, et al. This paper provides a relatively comprehensive review on the progress of conductive polymer and composite as sensitive film for sensors to chemical vapors including patents, papers and our preliminary research results. Especially, the feature of conjugated polymers, the processing technology, doping characteristics and some factors affecting gas responses are discussed. Otherwise, the developments of nanostructured conductive polymer and organic-inorganic hybrid film sensor with high sensitivity and rapid response to vapors are also described, and some suggestions are proposed.

  16. Micro Sun Sensor for Spacecraft

    NASA Technical Reports Server (NTRS)

    Mobasser, Sohrab; Liebe, Carl; Bae, Youngsam; Schroeder, Jeffrey; Wrigley, Chris

    2004-01-01

    A report describes the development of a compact micro Sun sensor for use as a part of the attitude determination subsystem aboard future miniature spacecraft and planetary robotic vehicles. The prototype unit has a mass of only 9 g, a volume of only 4.2 cm(sup 3), a power consumption of only 30 mW, and a 120 degree field of view. The unit has demonstrated an accuracy of 1 arcminute. The unit consists of a multiple pinhole camera: A micromachined mask containing a rectangular array of microscopic pinholes, machined utilizing the microectromechanical systems (MEMS), is mounted in front of an active-pixel sensor (APS) image detector. The APS consists of a 512 x 512-pixel array, on-chip 10-bit analog to digital converter (ADC), on-chip bias generation, and on-chip timing control for self-sequencing and easy programmability. The digitized output of the APS is processed to compute the centroids of the pinhole Sun images on the APS. The Sun angle, relative to a coordinate system fixed to the sensor unit, is then computed from the positions of the centroids.

  17. Chronocoulometry for quantitative control of mass removal in micro-structures and sensors

    SciTech Connect

    Nowakowski, B. K.; Smith, S. T.; Pratt, J. R.; Shaw, G. A.

    2012-10-15

    In this work, tungsten wires have been etched in a KOH electrolyte solution. Based on the oxidation state of the electrolytic dissolution reaction's product and time integration of the Faradaic current produced during the reaction, this method is capable of providing a direct measurement of the change in mass of a structure from anodic dissolution. To assess the application of this process for controlled mass removal spanning sub-micrograms to milligrams, two experimental studies and accompanying uncertainty analyses have been undertaken. In the first of these, 5 tungsten wires of length 30 mm were used to remove mass values ranging from 50 to 350 {mu}g. Uncertainty estimates indicate relative combined standard uncertainties of less than 0.3% in the mass changes determined from the measurement of Faradaic current. Comparison of the mass change determined using the electrolytic method, and using a precision ultra-microbalance agreed within this uncertainty. The charge-based method was then applied to modify the dynamic characteristics of a quartz tuning fork oscillator. In these experiments, tungsten fiber attached to one tine of the oscillator was etched in 5 {mu}g increments up to 120 {mu}g of total removed mass. In general, frequency shifts of 2.8 Hz{center_dot}{mu}g{sup -1} were observed, indicating sub-microgram resolution for the characterization of probes based on frequency shift and charge-based mass measurement. Taken together, this study provides the basis for a precision method for determining changes in mass based on electrical measurements from an electrochemical system. The utility of this technique is demonstrated through controlled modification of the dynamic properties of a mechanical oscillator.

  18. Chronocoulometry for quantitative control of mass removal in micro-structures and sensors

    NASA Astrophysics Data System (ADS)

    Nowakowski, B. K.; Smith, S. T.; Pratt, J. R.; Shaw, G. A.

    2012-10-01

    In this work, tungsten wires have been etched in a KOH electrolyte solution. Based on the oxidation state of the electrolytic dissolution reaction's product and time integration of the Faradaic current produced during the reaction, this method is capable of providing a direct measurement of the change in mass of a structure from anodic dissolution. To assess the application of this process for controlled mass removal spanning sub-micrograms to milligrams, two experimental studies and accompanying uncertainty analyses have been undertaken. In the first of these, 5 tungsten wires of length 30 mm were used to remove mass values ranging from 50 to 350 μg. Uncertainty estimates indicate relative combined standard uncertainties of less than 0.3% in the mass changes determined from the measurement of Faradaic current. Comparison of the mass change determined using the electrolytic method, and using a precision ultra-microbalance agreed within this uncertainty. The charge-based method was then applied to modify the dynamic characteristics of a quartz tuning fork oscillator. In these experiments, tungsten fiber attached to one tine of the oscillator was etched in 5 μg increments up to 120 μg of total removed mass. In general, frequency shifts of 2.8 Hz.μg-1 were observed, indicating sub-microgram resolution for the characterization of probes based on frequency shift and charge-based mass measurement. Taken together, this study provides the basis for a precision method for determining changes in mass based on electrical measurements from an electrochemical system. The utility of this technique is demonstrated through controlled modification of the dynamic properties of a mechanical oscillator.

  19. Flight Qualified Micro Sun Sensor

    NASA Technical Reports Server (NTRS)

    Liebe, Carl Christian; Mobasser, Sohrab; Wrigley, Chris; Schroeder, Jeffrey; Bae, Youngsam; Naegle, James; Katanyoutanant, Sunant; Jerebets, Sergei; Schatzel, Donald; Lee, Choonsup

    2007-01-01

    A prototype small, lightweight micro Sun sensor (MSS) has been flight qualified as part of the attitude-determination system of a spacecraft or for Mars surface operations. The MSS has previously been reported at a very early stage of development in NASA Tech Briefs, Vol. 28, No. 1 (January 2004). An MSS is essentially a miniature multiple-pinhole electronic camera combined with digital processing electronics that functions analogously to a sundial. A micromachined mask containing a number of microscopic pinholes is mounted in front of an active-pixel sensor (APS). Electronic circuits for controlling the operation of the APS, readout from the pixel photodetectors, and analog-to-digital conversion are all integrated onto the same chip along with the APS. The digital processing includes computation of the centroids of the pinhole Sun images on the APS. The spacecraft computer has the task of converting the Sun centroids into Sun angles utilizing a calibration polynomial. The micromachined mask comprises a 500-micron-thick silicon wafer, onto which is deposited a 57-nm-thick chromium adhesion- promotion layer followed by a 200-nm-thick gold light-absorption layer. The pinholes, 50 microns in diameter, are formed in the gold layer by photolithography. The chromium layer is thin enough to be penetrable by an amount of Sunlight adequate to form measurable pinhole images. A spacer frame between the mask and the APS maintains a gap of .1 mm between the pinhole plane and the photodetector plane of the APS. To minimize data volume, mass, and power consumption, the digital processing of the APS readouts takes place in a single field-programmable gate array (FPGA). The particular FPGA is a radiation- tolerant unit that contains .32,000 gates. No external memory is used so the FPGA calculates the centroids in real time as pixels are read off the APS with minimal internal memory. To enable the MSS to fit into a small package, the APS, the FPGA, and other components are mounted

  20. Micro-sensor thin-film anemometer

    NASA Technical Reports Server (NTRS)

    Sheplak, Mark (Inventor); McGinley, Catherine B. (Inventor); Spina, Eric F. (Inventor); Stephens, Ralph M. (Inventor); Hopson, Jr., Purnell (Inventor); Cruz, Vincent B. (Inventor)

    1996-01-01

    A device for measuring turbulence in high-speed flows is provided which includes a micro-sensor thin-film probe. The probe is formed from a single crystal of aluminum oxide having a 14.degree. half-wedge shaped portion. The tip of the half-wedge is rounded and has a thin-film sensor attached along the stagnation line. The bottom surface of the half-wedge is tilted upward to relieve shock induced disturbances created by the curved tip of the half-wedge. The sensor is applied using a microphotolithography technique.

  1. Electrokinetics Models for Micro and Nano Fluidic Impedance Sensors

    DTIC Science & Technology

    2010-11-01

    1 ELECTROKINETICS MODELS FOR MICRO AND NANO FLUIDIC IMPEDANCE SENSORS Yi Wang*, Hongjun Song, Ketan Bhatt, Kapil Pant CFD Research Corporation...analysis, design, and protocol development of novel micro - and nano - fluidics based impedance sensors. 1. INTRODUCTION Exposure to toxic...electrokinetic transport process at the micro - and nano -scale and to interrogate the sensor performance subject to the variations in design

  2. Revolution of Sensors in Micro-Electromechanical Systems

    NASA Astrophysics Data System (ADS)

    Esashi, Masayoshi

    2012-08-01

    Microsensors realized by micro-electromechanical systems (MEMS) technology play a key role as the input devices of systems. In this report, the following sensors are reviewed: piezoresistive and capacitive pressure sensors, surface acoustic wave (SAW) wireless pressure sensors, tactile sensor networks for robots, accelerometers, angular velocity sensors (gyroscopes), range image sensors using optical scanners, infrared imagers, chemical sensing systems as Fourier transform infrared (FTIR) spectroscopy and gas chromatography, flow sensors for fluids, and medical sensors such as ultrafine optical-fiber blood pressure sensors and implantable pressure sensors.

  3. CO Sensing Performance of a Micro Thermoelectric Gas Sensor with AuPtPd/SnO₂ Catalyst and Effects of a Double Catalyst Structure with Pt/α-Al₂O₃.

    PubMed

    Goto, Tomoyo; Itoh, Toshio; Akamatsu, Takafumi; Shin, Woosuck

    2015-12-15

    The CO sensing properties of a micro thermoelectric gas sensor (micro-TGS) with a double AuPtPd/SnO₂ and Pt/α-Al₂O₃ catalyst were investigated. While several nanometer sized Pt and Pd particles were uniformly dispersed on SnO₂, the Au particles were aggregated as particles measuring >10 nm in diameter. In situ diffuse reflectance Fourier transform Infrared spectroscopy (DRIFT) analysis of the catalyst showed a CO adsorption peak on Pt and Pd, but no clear peak corresponding to the interaction between CO and Au was detected. Up to 200 °C, CO combustion was more temperature dependent than that of H₂, while H₂ combustion was activated by repeated exposure to H₂ gas during the periodic gas test. Selective CO sensing of the micro-TGS against H₂ was attempted using a double catalyst structure with 0.3-30 wt% Pt/α-Al₂O₃ as a counterpart combustion catalyst. The sensor output of the micro-TGS decreased with increasing Pt content in the Pt/α-Al₂O₃ catalyst, by cancelling out the combustion heat from the AuPtPd/SnO₂ catalyst. In addition, the AuPtPd/SnO₂ and 0.3 wt% Pt/α-Al₂O₃ double catalyst sensor showed good and selective CO detection. We therefore demonstrated that our micro-TGS with double catalyst structure is useful for controlling the gas selectivity of CO against H₂.

  4. Hair-based sensors for micro-autonomous systems

    NASA Astrophysics Data System (ADS)

    Sadeghi, Mahdi M.; Peterson, Rebecca L.; Najafi, Khalil

    2012-06-01

    We seek to harness microelectromechanical systems (MEMS) technologies to build biomimetic devices for low-power, high-performance, robust sensors and actuators on micro-autonomous robot platforms. Hair is used abundantly in nature for a variety of functions including balance and inertial sensing, flow sensing and aerodynamic (air foil) control, tactile and touch sensing, insulation and temperature control, particle filtering, and gas/chemical sensing. Biological hairs, which are typically characterized by large surface/volume ratios and mechanical amplification of movement, can be distributed in large numbers over large areas providing unprecedented sensitivity, redundancy, and stability (robustness). Local neural transduction allows for space- and power-efficient signal processing. Moreover by varying the hair structure and transduction mechanism, the basic hair form can be used for a wide diversity of functions. In this paper, by exploiting a novel wafer-level, bubble-free liquid encapsulation technology, we make arrays of micro-hydraulic cells capable of electrostatic actuation and hydraulic amplification, which enables high force/high deflection actuation and extremely sensitive detection (sensing) at low power. By attachment of cilia (hair) to the micro-hydraulic cell, air flow sensors with excellent sensitivity (< few cm/s) and dynamic range (> 10 m/s) have been built. A second-generation design has significantly reduced the sensor response time while maintaining sensitivity of about 2 cm/s and dynamic range of more than 15 m/s. These sensors can be used for dynamic flight control of flying robots or for situational awareness in surveillance applications. The core biomimetic technologies developed are applicable to a broad range of sensors and actuators.

  5. Micro-position sensor using faraday effect

    SciTech Connect

    McElfresh, Michael; Lucas, Matthew; Silveira, Joseph P.; Groves, Scott E.

    2007-02-27

    A micro-position sensor and sensing system using the Faraday Effect. The sensor uses a permanent magnet to provide a magnetic field, and a magneto-optic material positioned in the magnetic field for rotating the plane of polarization of polarized light transmitted through the magneto-optic material. The magnet is independently movable relative to the magneto-optic material so as to rotate the plane of polarization of the polarized light as a function of the relative position of the magnet. In this manner, the position of the magnet relative to the magneto-optic material may be determined from the rotated polarized light. The sensing system also includes a light source, such as a laser or LED, for producing polarized light, and an optical fiber which is connected to the light source and to the magneto-optic material at a sensing end of the optical fiber. Processing electronics, such as a polarimeter, are also provided for determining the Faraday rotation of the plane of polarization of the back-reflected polarized light to determine the position of the magnet relative to the sensing end of the optical fiber.

  6. Micro-lens maker equation of a CMOS image sensor

    NASA Astrophysics Data System (ADS)

    Wu, Yang

    2007-09-01

    The demand of a large resolution CMOS image sensor (CIS) in a small package drives the pixel pitch size down to the neighborhood of 2 μm. Double-micro-lens (ML) structure is a promising technology to obtain the high focusing capability required by such a small pixel. In this work, an optical model of a double-ML is derived from the well-known lens maker equation. This model predicts the critical back focal length (BFL) and the effective focal length (EFL) of the double-ML embedded in the Back-End-Of-The-Line (BEOL) stack. Explained by this model, a design guideline is provided to optimize the amount of light collected by the photo diode area for a good quantum efficiency (QE), which is crucial to the sensitivity of the sensor.

  7. Hydrostatic pressure sensor based on micro-cavities developed by the catastrophic fuse effect

    NASA Astrophysics Data System (ADS)

    Domingues, M. F.; Paixão, T.; Mesquita, E.; Alberto, N.; Antunes, P.; Varum, H.; André, P. S.

    2015-09-01

    In this work, an optical fiber hydrostatic pressure sensor based in Fabry-Perot micro-cavities is presented. These micro structures were generated by the recycling of optical fiber previously damaged by the fiber fuse effect, resulting in a cost effective solution when compared with the traditional methods used to produce similar micro-cavities. The developed sensor was tested for pressures ranging from 20.0 to 190.0 cmH2O and a sensitivity of 53.7 +/- 2.6 pm/cmH2O for hydrostatic pressures below to 100 cmH2O was achieved.

  8. Design of micro-sensor-array detector for toxic gas

    NASA Astrophysics Data System (ADS)

    Liao, Hai-yang; Tian, Peng

    2010-08-01

    To quickly measure the trace concentration of the single component toxic gas (e.g. sarin), a micro-array toxic gas detector is designed. A 3 x 3 gas sensor array with metalloporphyrins as sensitive materials is introduced. A micro-capsule that can be easy to be loaded and unloaded is designed for the gas reaction. A fiber-array optical path is designed, which is based on the principle that gas sensors will show different colors after reaction with the toxic gas. The tricolor information about the concentration of gas is collected by the color liner CCD. A control handling system with C8051F021 MCU as the core is implemented and embedded into the detector to perform the functions of gas sampling, data collection and analysis calculation. Data acquisition experimental results show that the proposed scheme can effectively collect the color information after gas reaction. Moreover, the system has many important advantages, such as small size, compact structure, high degree of automation, fast detection speed and high performance-cost ratio, etc.

  9. Polymer-based micro flow sensor for dynamical flow measurements in hydraulic systems

    NASA Astrophysics Data System (ADS)

    Ahrens, R.; Festa, M.

    2010-06-01

    In this paper we present a micro flow sensor from a polymer for dynamical flow measurements in hydraulic systems. The flow sensor is based on the thermal anemometric principle and consists of two micro-structured housing shells from polysulfone (PSU) which form a small fluidic channel with a cross-section of 580 µm × 400 µm. In between there is a thin polyimide membrane supporting three gold track structures forming an electrical heater and two resistive thermometers which allows the detection of the flow direction, too. The complete sensor is inserted into the hydraulic system, but only a small bypass flow is directed through the fluidic channel by means of a special splitting system. Due to its small heat capacity, the sensor is suitable to detect flow pulsations up to about 1200 Hz which allows the sensor to be used for the condition monitoring or preventive maintenance of hydraulic systems.

  10. Integrated micro ring resonator displacement sensor for scanning probe microscopies

    NASA Astrophysics Data System (ADS)

    Kiyat, Isa; Kocabas, Coskun; Aydinli, Atilla

    2004-03-01

    We describe a novel displacement sensor for scanning probe microscopies using an integrated optical micro ring resonator. This device operates by means of monitoring the changes in the transmission spectrum of a high finesse micro ring resonator. Finite element method simulations were carried out to obtain the optimum sensor design and finite difference time domain simulation was used to obtain the transfer characteristics of micro ring resonators. Operation principles and sensitivity calculations are discussed in detail. To achieve high sensitivity, we have studied different types of ring resonator. The highest sensitivity is obtained in a race-track resonator. This new design should provide sensitivities as high as ~10-4 Å-1.

  11. Structural diagnostics using optical fiber sensors

    NASA Astrophysics Data System (ADS)

    Surace, Giuseppe; Chiaradia, Agostino

    1997-11-01

    After establishing the basis for assessing the structural implications of introducing a widespread sensor architecture in laminated composite materials in order to precisely identify and locate damage, the paper addresses the problem of structural diagnostics with a discussion of the development of several optical sensors. The research project will first investigate a passive optical fiber impact sensor to be implemented in the matrix of a composite material used in aeronautic and automotive applications. The senor's operating principle is based on the changes in propagation conditions occurring in a fiber subjected to transverse compression: under these circumstances, structural microdistortions produce local energy losses and hence a reduction in the optical power which propagates in the fiber and can be measured at its opposite end. As optical power losses also take place as a result of micro-bending of the optical fiber's longitudinal axis, a preliminary feasibility study will measure power attenuation versus fiber curve radius as the first step in the development of an optical fiber delamination sensor which locates separations between the layers of a composite material, i.e. debonding of sandwich panel core faces. Finally, an active impact sensor will be developed which uses optical fiber's sensitivity to pressure changes to detect the pressure gradient caused by an approaching vehicle or obstacle. The automotive industry will be able to make strategic use of these sensors, for example by installing them on vehicle sides to active the side airbag in the event of impact or collision.

  12. Micro-Pressure Sensors for Future Mars Missions

    NASA Technical Reports Server (NTRS)

    Catling, David C.

    1996-01-01

    The joint research interchange effort was directed at the following principal areas: u further development of NASA-Ames' Mars Micro-meteorology mission concept as a viable NASA space mission especially with regard to the science and instrument specifications u interaction with the flight team from NASA's New Millennium 'Deep-Space 2' (DS-2) mission with regard to selection and design of micro-pressure sensors for Mars u further development of micro-pressure sensors suitable for Mars The research work undertaken in the course of the Joint Research Interchange should be placed in the context of an ongoing planetary exploration objective to characterize the climate system on Mars. In particular, a network of small probes globally-distributed on the surface of the planet has often been cited as the only way to address this particular science goal. A team from NASA Ames has proposed such a mission called the Micrometeorology mission, or 'Micro-met' for short. Surface pressure data are all that are required, in principle, to calculate the Martian atmospheric circulation, provided that simultaneous orbital measurements of the atmosphere are also obtained. Consequently, in the proposed Micro-met mission a large number of landers would measure barometric pressure at various locations around Mars, each equipped with a micro-pressure sensor. Much of the time on the JRI was therefore spent working with the engineers and scientists concerned with Micro-met to develop this particular mission concept into a more realistic proposition.

  13. Batch patterning micro circuits and sensors with excimer laser machine

    NASA Astrophysics Data System (ADS)

    Yang, Ren; Pyka, Ralph; Kramer, Dennis; Mata, John; Souter, Matt; Thompson, Steven

    2008-02-01

    This paper will present the direct photo patterning of micro circuits and sensors with a XeCl excimer laser photo ablation system. The working principle and the ablation equipment for photo ablation of conductive thin film on polymer are described. Both large sheets and reel-to-reel webs can be ablated on this excimer laser photo ablation system. The ablation strategies and alignment strategies for the micro circuits and sensors are introduced. The test results show ablation results with high resolution, high throughput, high yield and cost-efficiency. This clearly shows that excimer laser photo ablation of the conductive materials on polymer substrates is a good choice for industrial mass product fabrication of low priced, disposable micro circuit and sensor devices.

  14. Micro-optics technology and sensor systems applications

    NASA Technical Reports Server (NTRS)

    Gal, George; Herman, B.; Anderson, W.; Whitney, R.; Morrow, H.

    1993-01-01

    The current generation of electro-optical sensors utilizing refractive and reflective optical elements require sophisticated, complex, and expensive designs. Advanced-technology-based electro-optical sensors of minimum size and weight require miniaturization of optical, electrical, and mechanical devices with an increasing trend toward integration of various components. Micro-optics technology has the potential in a number of areas to simplify optical design with improved performance. This includes internally cooled apertures, hybrid optical design, microlenses, dispersive multicolor microlenses, active dither, electronically controlled optical beam steer, and microscopic integration of micro-optics, detectors, and signal processing layers. This paper describes our approach to the development of micro-optics technology with our main emphasis for sensors applications.

  15. Functional micro/nanostructures: simple synthesis and application in sensors, fuel cells, and gene delivery.

    PubMed

    Guo, Shaojun; Wang, Erkang

    2011-07-19

    In order to develop new, high technology devices for a variety of applications, researchers would like to better control the structure and function of micro/nanomaterials through an understanding of the role of size, shape, architecture, composition, hybridization, molecular engineering, assembly, and microstructure. However, researchers continue to face great challenges in the construction of well-defined micro/nanomaterials with diverse morphologies. At the same time, the research interface where micro/nanomaterials meet electrochemistry, analytical chemistry, biomedicine, and other fields provides rich opportunities to reveal new chemical, physical, and biological properties of micro/nanomaterials and to uncover many new functions and applications of these materials. In this Account, we describe our recent progress in the construction of novel inorganic and polymer nanostructures formed through different simple strategies. Our synthetic strategies include wet-chemical and electrochemical methods for the controlled production of inorganic and polymer nanomaterials with well-defined morphologies. These methods are both facile and reliable, allowing us to produce high-quality micro/nanostructures, such as nanoplates, micro/nanoflowers, monodisperse micro/nanoparticles, nanowires, nanobelts, and polyhedron and even diverse hybrid structures. We implemented a series of approaches to address the challenges in the preparation of new functional micro/nanomaterials for a variety of important applications This Account also highlights new or enhanced applications of certain micro/nanomaterials in sensing applications. We singled out analytical techniques that take advantage of particular properties of micro/nanomaterials. Then by rationally tailoring experimental parameters, we readily and selectively obtained different types of micro/nanomaterials with novel morphologies with high performance in applications such as electrochemical sensors, electrochemiluminescent sensors

  16. Sensor technology for smart structures

    NASA Technical Reports Server (NTRS)

    Rogowski, R. S.; Heyman, J. S.; Holben, M. S., Jr.; Dehart, D. W.; Doederlein, T.

    1989-01-01

    Advanced aerospace structures are discussed that will very likely be fabricated with integral sensors, actuators, and microprocessors for monitoring and dynamic control of configuration. The concept of 'smart structures' integrates fiber-optic sensor technology with advanced composite materials, whereby the optical fibers are embedded in a composite material and provide internal sensing capability for monitoring parameters which are important for the safety, performance, and reliability of the material and the structure. Along with other research facilities, NASA has initiated a cooperative program to design, fabricate, and test composite trusses, tubes, and flat panels with embedded optical fibers for testing and developing prototype smart structures. It is shown that fiber-optic sensor technology can be combined with advanced material and structure concepts to produce a new class of materials with internal sensors for health monitoring of structures.

  17. A Micro Pressure Sensor with SU-8 Polymer

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaohong; Yin, Yonghua; Zheng, Xiaohu

    This paper investigated novel wireless RF pressure sensor fabricated with SU-8 polymer. To achieve highly simplified fabrication processes and designs for high-reliable operation, a passive wireless sensors were researched. SU-8 polymer-based micro pressure sensor was fabricated by micro-electro-mechenical system (MEMS) based batch process. The sensor consists of an inductor (L) interconnected with pressure-variable capacitor (C) to form a LC resonant circuit. Fabricated devices measure 4 × 3 mm2 in size and houses 9 turns of Cu electro-plated 100 nH coil. In this system, RF signal was transmitted from external antenna to the fabricated LC resonator. By detecting this abrupt resonant frequency shift of the fabricated device, the pressure change of the device can be measured by wireless method.

  18. A Novel Micro-cantilever Based Angular Speed Sensor Controlled Piezoelectrically and Tuned by Electrostatic Actuators

    NASA Astrophysics Data System (ADS)

    Shah-Mohammadi-Azar, A.; Shabani, R.; Rezazadeh, G.

    2015-11-01

    In this paper a novel sensor is proposed to measure rotational shafts speed. The sensor is composed of a micro-cantilever, with a piezoelectric actuator layer on the upper surface and a sensor layer on the lower surface. The sensor is attached to the shaft while the deflection of the micro-cantilever, due to centrifugal force of the rotating shaft, is actively controlled. Therefore the sensor deflection is suppressed and the controller output or the piezoelectric actuating voltage is employed to measure the angular speed of the shaft (Force balance technique). The micro-cantilever is symmetrically located between two electrodes giving it a wider operating range and also increasing its sensitivity. Imposing different electrostatic bias voltages alters the equivalent stiffness of the structure and consequently affects the micro-beam deflections and the controller outputs. Simulation results reveal that for lower velocities the resolution increases by increasing the bias voltages. It is shown that decreasing the micro-beam length increases the measurable velocity range and conversely decreasing the electrodes gap decreases the maximum measurable speed.

  19. Parametric excitation of a micro Coriolis mass flow sensor

    NASA Astrophysics Data System (ADS)

    Droogendijk, H.; Groenesteijn, J.; Haneveld, J.; Sanders, R. G. P.; Wiegerink, R. J.; Lammerink, T. S. J.; Lötters, J. C.; Krijnen, G. J. M.

    2012-11-01

    We demonstrate that a micro Coriolis mass flow sensor can be excited in its torsional movement by applying parametric excitation. Using AC-bias voltages for periodic electrostatic spring softening, the flow-filled tube exhibits a steady vibration at suitable voltage settings. Measurements show that the sensor for this type of excitation can be used to measure water flow rates within a range of 0 ± 500 μl/h with an accuracy of 1% full scale error.

  20. Micro-displacement fiber sensor using two-frequency interferometry

    NASA Technical Reports Server (NTRS)

    Tedjojuwono, Ken K.

    1991-01-01

    A He-Ne Zeeman laser has been utilized as a two-frequency light source in a Michelson-type micro-displacement fiber sensor. A polarization maintaining fiber has been installed in the sensing arm, which facilitates flexibility and allows the sensing region to be remotely located. This fiber sensing arm is arranged to replace a quarterwave plate component. The fiber sensor system has a resolution of half a micrometer.

  1. Structure factor in chemical sensorics

    SciTech Connect

    Gutman, E.E.; Belysheva, T.V.; Ryabtsev, S.V.; Chibirova, F.H.

    1996-12-31

    Additions of metals and metal oxides to semiconductor metal oxide films improve usually their gas sensitive sensor properties namely for detection of toxic and flammable gases. The aim of this work is the obtaining of new data and the elucidation of the role of the structure and the chemical nature of promoters in semiconductor gas sensorics. As examples, the authors consider the systems CO-SnO{sub 2} and O{sub 3}-In{sub 2}O{sub 3} sensors. The elaboration of mentioned sensors is aimed at the measurement of small gas constituent in Earth`s and Marth`s atmospheres.

  2. Analysis of Mach-Zehnder interferometric micro-opto-electro-mechanical (MOEM) pressure sensor

    NASA Astrophysics Data System (ADS)

    Srinivas, Talabuttala; Pattnaik, Prasant K.; Narayana, T. Badri; Selvarajan, Ananth

    1999-11-01

    Combination of Integrated Optics and micro-machining technologies offer immense potential for sensor applications. Small mechanical deformations can often produce considerable changes in optical properties of devices resulting in drastically improved sensitivities. Here we prose and analyze a novel pressure sensor consisting of integrated optic Mach-Zehnder interferometer whose sensing arm is fabricated on a silicon micro-machined diaphragm. The analysis consists of determining the changes in optical output corresponding to the diaphragm deflections due to impressed pressure. Dynamical equations of motion are solved and resulting displacement fields are related to refractive index and optical path length changes of the Mach-Zehnder interferometer. Results can be used to obtain the change in sensitivity due to change sin path length and refractive index variations. The analysis can easily be applied to other MOEM sensor devices like those consisting of micro-machined vibrating cantilevers and bridges controlling optical waveguides, directional couplers or multi-mode-multi-waveguide structures.

  3. Polymer-based micro-array sensors

    NASA Astrophysics Data System (ADS)

    Sharpe, Ruben B. A.; Rensing, Peter A.; van Heck, Gert T.; Allard, Bart A. M.; Koetse, Marc M.; Meulendijks, Nicole N. M. M.; Kruijt, Peter G. M.; Tijdink, Marcel W. W. J.; de Zwart, René M.; van Veen, Sjaak J. J. F.; Schoo, Herman F. M.

    2007-09-01

    The introduction in the market of ubiquitous sensing applications relies heavily on the availability of affordable sensors. Key in the cost of a sensor is its modus of manufacture. In this paper a sensing scheme is presented, in which the signal transduction is based on an induced change in the optical path between an organic light emitting diode (OLED) and an organic photovoltaic (OPV) array. Using this platform, several aspects of cost efficient manufacturing technology are investigated. These aspects include the intrinsic printability of the active (OLED, responsive coating and OPV) components, which allows control of the local sensor functionality and sensitivity. It offers a large amount of freedom in sensor layout, while using relatively few process steps. Also investigated is the ability to realize the active devices on foil, which enables high throughput processing (e.g. in a reel-to-reel scheme). Moreover, the presented generic sensing scheme is of a modular design. It allows easy switching of the sensor functionality mostly by simply changing the transduction module. Since this does not affect the production parameters of the other components, these may be standardized, thus invoking favorable economies of scale.

  4. Micro-sensors for in-situ meteorological measurements

    NASA Technical Reports Server (NTRS)

    Crisp, David; Kaiser, William J.; Vanzandt, Thomas R.; Tillman, James E.

    1993-01-01

    Improved in-situ meteorological measurements are needed for monitoring the weather and climate of the terrestrial and Martian atmospheres. We have initiated a program to assess the feasibility and utility of micro-sensors for precise in-situ meteorological measurements in these environments. Sensors are being developed for measuring pressure, temperature, wind velocity, humidity, and aerosol amounts. Silicon micro-machining and large scale integration technologies are being used to make sensors that are small, rugged, lightweight, and require very little power. Our long-term goal is to develop very accurate miniaturized sensors that can be incorporated into complete instrument packages or 'micro weather stations,' and deployed on a variety of platforms. If conventional commercially available silicon production techniques can be used to fabricate these sensor packages, it will eventually be possible to mass-produce them at low cost. For studies of the Earth's troposphere and stratosphere, they could be deployed on aircraft, dropsondes, radiosondes, or autonomous surface stations at remote sites. Improved sensor accuracy and reduced sensor cost are the primary challenges for these applications. For studies of the Martian atmosphere, these sensor packages could be incorporated into the small entry probes and surface landers that are being planned for the Mars Environmental SURvey (MESUR) Mission. That decade-long program will deploy a global network of small stations on the Martian surface for monitoring meteorological and geological processes. Low mass, low power, durability, large dynamic range and calibration stability are the principal challenges for this application. Our progress on each of these sensor types is presented.

  5. Method of Forming Micro-Sensor Thin-Film Anemometer

    NASA Technical Reports Server (NTRS)

    Sheplak, Mark (Inventor); McGinley, Catherine B. (Inventor); Spina, Eric F. (Inventor); Stephens, Ralph M. (Inventor); Hopson, Purnell, Jr. (Inventor); Cruz, Vincent B. (Inventor)

    2000-01-01

    A device for measuring turbulence in high-speed flows is provided which includes a micro- sensor thin-film probe. The probe is formed from a single crystal of aluminum oxide having a 14 deg half-wedge shaped portion. The tip of the half-wedge is rounded and has a thin-film sensor attached along the stagnation line. The bottom surface of the half-wedge is tilted upward to relieve shock induced disturbances created by the curved tip of the half-wedge. The sensor is applied using a microphotolithography technique.

  6. A Micro Aerosol Sensor for the Measurement of Airborne Ultrafine Particles

    PubMed Central

    Zhang, Chao; Zhu, Rong; Yang, Wenming

    2016-01-01

    Particle number concentration and particle size are the two key parameters used to characterize exposure to airborne nanoparticles or ultrafine particles that have attracted the most attention. This paper proposes a simple micro aerosol sensor for detecting the number concentration and particle size of ultrafine particles with diameters from 50 to 253 nm based on electrical diffusion charging. The sensor is composed of a micro channel and a couple of planar electrodes printed on two circuit boards assembled in parallel, which thus integrate charging, precipitating and measurement elements into one chip, the overall size of which is 98 × 38 × 25 mm3. The experiment results demonstrate that the sensor is useful for measuring monodisperse aerosol particles with number concentrations from 300 to 2.5 × 104 /cm3 and particle sizes from 50 to 253 nm. The aerosol sensor has a simple structure and small size, which is favorable for use in handheld devices. PMID:26999156

  7. Carbon nanotubes on polymer-based pressure micro-sensor for manometric catheters

    NASA Astrophysics Data System (ADS)

    Teng, M. F.; Hariz, A.; Hsu, H. Y.; Omari, T.

    2008-12-01

    In this paper we investigate the fabrication process of a novel polymer based pressure micro-sensor for use in manometric measurements in medical diagnostics. Review and analysis of polymer materials properties and polymer based sensors has been carried out and has been reported by us elsewhere [1]. The interest in developing a novel polymer based flexible pressure micro-sensor was motivated by the numerous problems inherent in the currently available manometric catheters used in the hospitals. The most critical issue regarding existing catheters was the running and maintenance costs [2]. Thus expensive operation costs lead to reuse of the catheters, which increase the risk for disease transmission. The novel flexible polymer based pressure micro-sensor was build using SU-8, which is a special kind of negative photoresist. Single-walled carbon nanotubes (SWCNTs) and aluminum are used as the sensing material and contacting electrodes respectively. The pressure sensor diaphragm was first patterned on top of an oxidized silicon wafer using SU-8, followed by aluminum deposition to define the electrodes. The carbon nanotube is then deposited using dielectrophoresis (DEP) process. Once the carbon nanotubes are aligned in between these electrodes, the remaining of the sensor structure is formed using SU-8. Patterning of SU-8 and release from the substrate make the device ready for further testing of sensing ability. This research not only investigates the use of polymeric materials to build pressure sensors, but also explores the feasibility of full utilization of polymeric materials to replace conventional silicon materials in micro-sensors fabrication for use in medical environments. The completed sensor is expected to form an integral part of a large versatile sensing system. For example, the biocompatible artificial skin, is predicted to be capable of sensing force, pressure, temperature, and humidity, and may be used in such applications as medical and robotic system.

  8. Fabrication and Characterization of a Micro Methanol Sensor Using the CMOS-MEMS Technique.

    PubMed

    Fong, Chien-Fu; Dai, Ching-Liang; Wu, Chyan-Chyi

    2015-10-23

    A methanol microsensor integrated with a micro heater manufactured using the complementary metal oxide semiconductor (CMOS)-microelectromechanical system (MEMS) technique was presented. The sensor has a capability of detecting low concentration methanol gas. Structure of the sensor is composed of interdigitated electrodes, a sensitive film and a heater. The heater located under the interdigitated electrodes is utilized to provide a working temperature to the sensitive film. The sensitive film prepared by the sol-gel method is tin dioxide doped cadmium sulfide, which is deposited on the interdigitated electrodes. To obtain the suspended structure and deposit the sensitive film, the sensor needs a post-CMOS process to etch the sacrificial silicon dioxide layer and silicon substrate. The methanol senor is a resistive type. A readout circuit converts the resistance variation of the sensor into the output voltage. The experimental results show that the methanol sensor has a sensitivity of 0.18 V/ppm.

  9. Fabrication and Characterization of a Micro Methanol Sensor Using the CMOS-MEMS Technique

    PubMed Central

    Fong, Chien-Fu; Dai, Ching-Liang; Wu, Chyan-Chyi

    2015-01-01

    A methanol microsensor integrated with a micro heater manufactured using the complementary metal oxide semiconductor (CMOS)-microelectromechanical system (MEMS) technique was presented. The sensor has a capability of detecting low concentration methanol gas. Structure of the sensor is composed of interdigitated electrodes, a sensitive film and a heater. The heater located under the interdigitated electrodes is utilized to provide a working temperature to the sensitive film. The sensitive film prepared by the sol-gel method is tin dioxide doped cadmium sulfide, which is deposited on the interdigitated electrodes. To obtain the suspended structure and deposit the sensitive film, the sensor needs a post-CMOS process to etch the sacrificial silicon dioxide layer and silicon substrate. The methanol senor is a resistive type. A readout circuit converts the resistance variation of the sensor into the output voltage. The experimental results show that the methanol sensor has a sensitivity of 0.18 V/ppm. PMID:26512671

  10. Micro-optical Distributed Sensors for Aero Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Arnold, S.; Otugen, V.; Seasholtz, Richard G. (Technical Monitor)

    2003-01-01

    The objective of this research is to develop micro-opto-mechanical system (MOMS)-based sensors for time- and space-resolved measurements of flow properties in aerodynamics applications. The measurement technique we propose uses optical resonances in dielectric micro-spheres that can be excited by radiation tunneling from optical fibers. It exploits the tunneling-induced and morphology-dependent shifts in the resonant frequencies. The shift in the resonant frequency is dependent on the size, shape, and index of refraction of the micro-sphere. A physical change in the environment surrounding a micro-bead can change one or more of these properties of the sphere thereby causing a shift in frequency of resonance. The change of the resonance frequency can be detected with high resolution by scanning a frequency-tunable laser that is coupled into the fiber and observing the transmission spectrum at the output of the fiber. It is expected that, in the future, the measurement concept will lead to a system of distributed micro-sensors providing spatial data resolved in time and space. The present project focuses on the development and demonstration of temperature sensors using the morphology-dependent optical resonances although in the latter part of the work, we will also develop a pressure sensor. During the period covered in this report, the optical and electronic equipment necessary for the experimental work was assembled and the experimental setup was designed for the single sensor temperature measurements. Software was developed for real-time tracking of the optical resonance shifts. Some preliminary experiments were also carried out to detect temperature using a single bead in a water bath.

  11. Demonstration of a refractometric sensor based on an optical micro-fiber three-beam interferometer

    NASA Astrophysics Data System (ADS)

    Han, Chunyang; Ding, Hui; Lv, Fangxing

    2014-12-01

    With diameter close to the wavelength of the guided light and high index contrast between the fiber and the surrounding, an optical micro-fiber shows a variety of interesting waveguiding properties, including widely tailorable optical confinement, strong evanescent fields and waveguide dispersion. Among various micro-fiber applications, optical sensing has been attracting increasing research interest due to its possibilities of realizing miniaturized fiber optic sensors with small footprint, high sensitivity, and low optical power consumption. Typical micro-fiber based sensing structures, including Michelson interferometer, Mach-Zenhder interferometer, Fabry-Perot interferometer, micro-fiber ring resonator, have been proposed. The sensitivity of these structures heavily related to the fraction of evanescent field outside micro-fiber. In this paper, we report the first theoretical and experimental study of a new type of refractometric sensor based on micro-fiber three-beam interferometer. Theoretical and experimental analysis reveals that the sensitivity is not only determined by the fraction of evanescent field outside the micro-fiber but also related to the values of interferometric arms. The sensitivity can be enhanced significantly when the effective lengths of the interferometric arms tends to be equal. We argue that this has great potential for increasing the sensitivity of refractive index detection.

  12. Demonstration of a refractometric sensor based on an optical micro-fiber three-beam interferometer.

    PubMed

    Han, Chunyang; Ding, Hui; Lv, Fangxing

    2014-12-16

    With diameter close to the wavelength of the guided light and high index contrast between the fiber and the surrounding, an optical micro-fiber shows a variety of interesting waveguiding properties, including widely tailorable optical confinement, strong evanescent fields and waveguide dispersion. Among various micro-fiber applications, optical sensing has been attracting increasing research interest due to its possibilities of realizing miniaturized fiber optic sensors with small footprint, high sensitivity, and low optical power consumption. Typical micro-fiber based sensing structures, including Michelson interferometer, Mach-Zenhder interferometer, Fabry-Perot interferometer, micro-fiber ring resonator, have been proposed. The sensitivity of these structures heavily related to the fraction of evanescent field outside micro-fiber. In this paper, we report the first theoretical and experimental study of a new type of refractometric sensor based on micro-fiber three-beam interferometer. Theoretical and experimental analysis reveals that the sensitivity is not only determined by the fraction of evanescent field outside the micro-fiber but also related to the values of interferometric arms. The sensitivity can be enhanced significantly when the effective lengths of the interferometric arms tends to be equal. We argue that this has great potential for increasing the sensitivity of refractive index detection.

  13. Innovative smart micro sensors for Army weaponry applications

    NASA Astrophysics Data System (ADS)

    Ruffin, Paul B.; Brantley, Christina; Edwards, Eugene

    2008-03-01

    Micro sensors offer the potential solution to cost, size, and weight issues associated with smart networked sensor systems designed for environmental/missile health monitoring and rocket out-gassing/fuel leak detection, as well as situational awareness on the battlefield. In collaboration with the University of Arkansas (Fayetteville), University of Alabama (Tuscaloosa and Birmingham), Alabama A&M University (Normal), and Streamline Automation (Huntsville, AL), scientists and engineers at the Army Aviation & Missile Research, Development, and Engineering Center (AMRDEC) are investigating several nano-based technologies to solve the problem of sensing extremely small levels of toxic gases associated with both chemical warfare agents (in air and liquids) and potential rocket motor leaks. Innovative techniques are being devised to adapt voltammetry, which is a well established technique for the detection and quantification of substances dissolved in liquids, to low-cost micro sensors for detecting airborne chemical agents and potential missile propellant leakages. In addition, a surface enhanced Raman scattering (SERS) technique, which enhances Raman scattered light by excitation of surface plasmons on nanoporous metal surfaces (nanospheres), is being investigated to develop novel smart sensors for the detection of chemical agents (including rocket motor out-gassing) and potential detection of home-made explosive devices. In this paper, results are delineated that are associated with experimental studies, which are conducted for the aforementioned cases and for several other nano-based technology approaches. The design challenges of each micro sensor technology approach are discussed. Finally, a comparative analysis of the various innovative micro-sensor techniques is provided.

  14. A novel air flow sensor from printed PEDOT micro-hairs

    NASA Astrophysics Data System (ADS)

    Parcell, J.; Aydemir, N.; Devaraj, H.; Travas-Sejdic, J.; Williams, D. E.; Aw, K. C.

    2013-11-01

    We report the creation of a low flow rate sensor from PEDOT micro-hairs. The hairs are printed as pipette-defined depositions using a nanopositioning system. The printing technique was developed for fabricating structures in 2D and 3D. Here micro-hairs with diameters of 4.4 μm were repeatedly extruded with constant heights. These hairs were then applied to produce a prototype flow rate sensor, which was shown to detect flows of 3.5 l min-1. Structural analysis was performed to demonstrate that the design can be modified to potentially observe flows as low as 0.5 l min-1. The results are extended to propose a practical digital flow rate sensor.

  15. CP-OCT sensor guided SMART micro-forceps

    NASA Astrophysics Data System (ADS)

    Song, Cheol; Gehlbach, Peter L.; Kang, Jin U.

    2014-02-01

    Even the most stable hands have unintended movements on the order of 50-100 microns within 0-15 Hz. Micro-forceps are one of the frequently used microsurgical tools used to grasp thin layers of tissue during microsurgery. Here, a handheld Smart Micromanipulation Aided Robotic-surgery Tool (SMART) micro-forceps is developed by integrating a fiber-optic common-path optical coherence tomography (CP-OCT) sensor into the micro-forceps. This forceps design could significantly improve performance by canceling unwanted hand tremor during the moment of a grasping. The basic grasping and peeling functions of the micro-forceps are evaluated in dry phantoms and in a biological tissue model.

  16. Micro-Vibration-Based Slip Detection in Tactile Force Sensors

    PubMed Central

    Fernandez, Raul; Payo, Ismael; Vazquez, Andres S.; Becedas, Jonathan

    2014-01-01

    Tactile sensing provides critical information, such as force, texture, shape or temperature, in manipulation tasks. In particular, tactile sensors traditionally used in robotics are emphasized in contact force determination for grasping control and object recognition. Nevertheless, slip detection is also crucial to successfully manipulate an object. Several approaches have appeared to detect slipping, the majority being a combination of complex sensors with complex algorithms. In this paper, we deal with simplicity, analyzing how a novel, but simple, algorithm, based on micro-vibration detection, can be used in a simple, but low-cost and durable, force sensor. We also analyze the results of using the same principle to detect slipping in other force sensors based on flexible parts. In particular, we show and compare the slip detection with: (i) a flexible finger, designed by the authors, acting as a force sensor; (ii) the finger torque sensor of a commercial robotic hand; (iii) a commercial six-axis force sensor mounted on the wrist of a robot; and (iv) a fingertip piezoresistive matrix sensor. PMID:24394598

  17. High temperature gradient micro-sensor for wall shear stress and flow direction measurements

    NASA Astrophysics Data System (ADS)

    Ghouila-Houri, C.; Claudel, J.; Gerbedoen, J.-C.; Gallas, Q.; Garnier, E.; Merlen, A.; Viard, R.; Talbi, A.; Pernod, P.

    2016-12-01

    We present an efficient and high-sensitive thermal micro-sensor for near wall flow parameters measurements. By combining substrate-free wire structure and mechanical support using silicon oxide micro-bridges, the sensor achieves a high temperature gradient, with wires reaching 1 mm long for only 3 μm wide over a 20 μm deep cavity. Elaborated to reach a compromise solution between conventional hot-films and hot-wire sensors, the sensor presents a high sensitivity to the wall shear stress and to the flow direction. The sensor can be mounted flush to the wall for research studies such as turbulence and near wall shear flow analysis, and for technical applications, such as flow control and separation detection. The fabrication process is CMOS-compatible and allows on-chip integration. The present letter describes the sensor elaboration, design, and micro-fabrication, then the electrical and thermal characterizations, and finally the calibration experiments in a turbulent boundary layer wind tunnel.

  18. Fly eye radar or micro-radar sensor technology

    NASA Astrophysics Data System (ADS)

    Molchanov, Pavlo; Asmolova, Olga

    2014-05-01

    To compensate for its eye's inability to point its eye at a target, the fly's eye consists of multiple angularly spaced sensors giving the fly the wide-area visual coverage it needs to detect and avoid the threats around him. Based on a similar concept a revolutionary new micro-radar sensor technology is proposed for detecting and tracking ground and/or airborne low profile low altitude targets in harsh urban environments. Distributed along a border or around a protected object (military facility and buildings, camp, stadium) small size, low power unattended radar sensors can be used for target detection and tracking, threat warning, pre-shot sniper protection and provides effective support for homeland security. In addition it can provide 3D recognition and targets classification due to its use of five orders more pulses than any scanning radar to each space point, by using few points of view, diversity signals and intelligent processing. The application of an array of directional antennas eliminates the need for a mechanical scanning antenna or phase processor. It radically decreases radar size and increases bearing accuracy several folds. The proposed micro-radar sensors can be easy connected to one or several operators by point-to-point invisible protected communication. The directional antennas have higher gain, can be multi-frequency and connected to a multi-functional network. Fly eye micro-radars are inexpensive, can be expendable and will reduce cost of defense.

  19. Flexible Wing Base Micro Aerial Vehicles: Micro Air Vehicles (MAVs) for Surveillance and Remote Sensor Delivery

    NASA Technical Reports Server (NTRS)

    Ifju, Peter

    2002-01-01

    Micro Air Vehicles (MAVs) will be developed for tracking individuals, locating terrorist threats, and delivering remote sensors, for surveillance and chemical/biological agent detection. The tasks are: (1) Develop robust MAV platform capable of carrying sensor payload. (2) Develop fully autonomous capabilities for delivery of sensors to remote and distant locations. The current capabilities and accomplishments are: (1) Operational electric (inaudible) 6-inch MAVs with novel flexible wing, providing superior aerodynamic efficiency and control. (2) Vision-based flight stability and control (from on-board cameras).

  20. The Micro-Pillar Shear-Stress Sensor MPS3 for Turbulent Flow

    PubMed Central

    Große, Sebastian; Schröder, Wolfgang

    2009-01-01

    Wall-shear stress results from the relative motion of a fluid over a body surface as a consequence of the no-slip condition of the fluid in the vicinity of the wall. To determine the two-dimensional wall-shear stress distribution is of utter importance in theoretical and applied turbulence research. In this article, characteristics of the Micro-Pillar Shear-Stress Sensor MPS3, which has been shown to offer the potential to measure the two-directional dynamic wall-shear stress distribution in turbulent flows, will be summarized. After a brief general description of the sensor concept, material characteristics, possible sensor-structure related error sources, various sensitivity and distinct sensor performance aspects will be addressed. Especially, pressure-sensitivity related aspects will be discussed. This discussion will serve as ‘design rules’ for possible new fields of applications of the sensor technology. PMID:22574010

  1. Fiber optic micro sensor for the measurement of tendon forces.

    PubMed

    Behrmann, Gregory P; Hidler, Joseph; Mirotznik, Mark S

    2012-10-03

    A fiber optic sensor developed for the measurement of tendon forces was designed, numerically modeled, fabricated, and experimentally evaluated. The sensor incorporated fiber Bragg gratings and micro-fabricated stainless steel housings. A fiber Bragg grating is an optical device that is spectrally sensitive to axial strain. Stainless steel housings were designed to convert radial forces applied to the housing into axial forces that could be sensed by the fiber Bragg grating. The metal housings were fabricated by several methods including laser micromachining, swaging, and hydroforming. Designs are presented that allow for simultaneous temperature and force measurements as well as for simultaneous resolution of multi-axis forces.The sensor was experimentally evaluated by hydrostatic loading and in vitro testing. A commercial hydraulic burst tester was used to provide uniform pressures on the sensor in order to establish the linearity, repeatability, and accuracy characteristics of the sensor. The in vitro experiments were performed in excised tendon and in a dynamic gait simulator to simulate biological conditions. In both experimental conditions, the sensor was found to be a sensitive and reliable method for acquiring minimally invasive measurements of soft tissue forces. Our results suggest that this sensor will prove useful in a variety of biomechanical measurements.

  2. Fiber optic micro sensor for the measurement of tendon forces

    PubMed Central

    2012-01-01

    A fiber optic sensor developed for the measurement of tendon forces was designed, numerically modeled, fabricated, and experimentally evaluated. The sensor incorporated fiber Bragg gratings and micro-fabricated stainless steel housings. A fiber Bragg grating is an optical device that is spectrally sensitive to axial strain. Stainless steel housings were designed to convert radial forces applied to the housing into axial forces that could be sensed by the fiber Bragg grating. The metal housings were fabricated by several methods including laser micromachining, swaging, and hydroforming. Designs are presented that allow for simultaneous temperature and force measurements as well as for simultaneous resolution of multi-axis forces. The sensor was experimentally evaluated by hydrostatic loading and in vitro testing. A commercial hydraulic burst tester was used to provide uniform pressures on the sensor in order to establish the linearity, repeatability, and accuracy characteristics of the sensor. The in vitro experiments were performed in excised tendon and in a dynamic gait simulator to simulate biological conditions. In both experimental conditions, the sensor was found to be a sensitive and reliable method for acquiring minimally invasive measurements of soft tissue forces. Our results suggest that this sensor will prove useful in a variety of biomechanical measurements. PMID:23033868

  3. Silicon Nanotips Antireflection Surface for Micro Sun Sensor

    NASA Technical Reports Server (NTRS)

    Bae, Sam Y.; Lee, Choonsup; Mobasser, Sohrab; Manohara, Harish

    2006-01-01

    We have developed a new technique to fabricate antireflection surface using silicon nano-tips for use on a micro sun sensor for Mars rovers. We have achieved randomly distributed nano-tips of radius spanning from 20 nm to 100 nm and aspect ratio of 200 using a two-step dry etching process. The 30(deg) specular reflectance at the target wavelength of 1 (mu)m is only about 0.09 %, nearly three orders of magnitude lower than that of bare silicon, and the hemispherical reflectance is 8%. By changing the density and aspect ratio of these nanotips, the change in reflectance is demonstrated. Using surfaces covered with these nano-tips, the critical problem of ghost images that are caused by multiple internal reflections in a micro sun sensor was solved.

  4. Multiplexing of six micro-displacement suspended-core Sagnac interferometer sensors with a Raman-Erbium fiber laser.

    PubMed

    Bravo, Mikel; Fernández-Vallejo, Montserrat; Echapare, Mikel; López-Amo, Manuel; Kobelke, J; Schuster, K

    2013-02-11

    This work experimentally demonstrates a long-range optical fiber sensing network for the multiplexing of fiber sensors based on photonic crystal fibers. Specifically, six photonic crystal fiber sensors which are based on a Sagnac interferometer that includes a suspended-core fiber have been used. These sensors offer a high sensitivity for micro-displacement measurements. The fiber sensor network presents a ladder structure and its operation mode is based on a fiber ring laser which combines Raman and Erbium doped fiber amplification. Thus, we show the first demonstration of photonic crystal fiber sensors for remote measurement applications up to 75 km.

  5. Analysis of the reflection of a micro drop fiber sensor

    NASA Astrophysics Data System (ADS)

    Sun, Weimin; Liu, Qiang; Zhao, Lei; Li, Yingjuan; Yuan, Libo

    2005-01-01

    Micro drop fiber sensors are effective tools for measuring characters of liquids. These types of sensors are wildly used in biotechnology, beverage and food markets. For a fiber micro drop sensor, the signal of the output light is wavy with two peaks, normally. Carefully analyzing the wavy process can identify the liquid components. Understanding the reason of forming this wavy signal is important to design a suitable sensing head and to choose a suitable signal-processing method. The dripping process of a type of liquids is relative to the characters of the liquid and the shape of the sensing head. The quasi-Gauss model of the light field from the input-fiber end is used to analyse the distribution of the light field in the liquid drop. In addition, considering the characters of the liquid to be measured, the dripping process of the optical signal from the output-fiber end can be expected. The reflection surface of the micro drop varies as serials of spheres with different radiuses and global centers. The intensity of the reflection light changes with the shape of the surface. The varying process of the intensity relates to the tense, refractive index, transmission et al. To support the analyse above, an experimental system is established. In the system, LED is chosen as the light source and the PIN transform the light signal to the electrical signal, which is collected by a data acquisition card. An on-line testing system is made to check the theory discussed above.

  6. In2O3-based micro gas sensor for detecting NO x gases

    NASA Astrophysics Data System (ADS)

    Kim, Bum-Joon; Song, In-Gyu; Kim, Jung-Sik

    2014-03-01

    In this study, NO x micro gas sensors for monitoring the indoor atmosphere of automobile were fabricated using MEMS (microelectromechanical system) technology and a sol-gel process. The sensing electrode and micro heater were designed to have a co-planar typed structure in a Pt thin film layer. The thermal characteristics of a micro heater array were analyzed using a finite element method (FEM). The chip size of the gas sensor was approximately 2 mm × 2 mm. Indium oxide as a sensing material for NO x gas was synthesized by a sol-gel process with indium isopropoxide as a precursor. Field emission Scanning electron microscopy and x-ray diffraction showed that particle size of the synthesized In2O3 was approximately 17-45 nm. The maximum gas sensitivity as the relative resistance ( R s = R gas / R air ) was observed at 275°C with a value of 8.0 at 1 ppm NO2 gas. The response (80% saturation) and recovery times were within 1 min. The sensing properties of NO2 gas exhibited linear behavior with increasing gas concentration. The sensing mechanism of the gas sensor was explained by the variations in the electron depletion layers and the adsorption of gas molecules on the In2O3 particle surface. These results suggest that in the future, MEMS-based gas sensors can be used as automotive-exhaust-gas sensors.

  7. A Micro-Thermal Sensor for Focal Therapy Applications

    PubMed Central

    Natesan, Harishankar; Hodges, Wyatt; Choi, Jeunghwan; Lubner, Sean; Dames, Chris; Bischof, John

    2016-01-01

    There is an urgent need for sensors deployed during focal therapies to inform treatment planning and in vivo monitoring in thin tissues. Specifically, the measurement of thermal properties, cooling surface contact, tissue thickness, blood flow and phase change with mm to sub mm accuracy are needed. As a proof of principle, we demonstrate that a micro-thermal sensor based on the supported “3ω” technique can achieve this in vitro under idealized conditions in 0.5 to 2 mm thick tissues relevant to cryoablation of the pulmonary vein (PV). To begin with “3ω” sensors were microfabricated onto flat glass as an idealization of a focal probe surface. The sensor was then used to make new measurements of ‘k’ (W/m.K) of porcine PV, esophagus, and phrenic nerve, all needed for PV cryoabalation treatment planning. Further, by modifying the sensor use from traditional to dynamic mode new measurements related to tissue vs. fluid (i.e. water) contact, fluid flow conditions, tissue thickness, and phase change were made. In summary, the in vitro idealized system data presented is promising and warrants future work to integrate and test supported “3ω” sensors on in vivo deployed focal therapy probe surfaces (i.e. balloons or catheters). PMID:26916460

  8. Micro-electromechanical sensors in the analytical field.

    PubMed

    Zougagh, Mohammed; Ríos, Angel

    2009-07-01

    Micro- and nano-electromechanical systems (MEMS and NEMS) for use as sensors represent one of the most exciting new fields in analytical chemistry today. These systems are advantageous over currently available non-miniaturized sensors, such as quartz crystal microbalances, thickness shear mode resonators, and flexural plate wave oscillators, because of their high sensitivity, low cost and easy integration into automated systems. In this article, we present and discuss the evolution in the use of MEMS and NEMS, which are basically cantilever-type sensors, as good analytical tools for a wide variety of applications. We discuss the analytical features and the practical potential of micro(nano)-cantilever sensors, which combine the synergetic advantages of selectivity, provided by their functionalization, and the high sensitivity, which is attributed largely to the extremely small size of the sensing element. An insight is given into the different types of functionalization and detection strategies and a critical discussion is presented on the existing state of the art concerning the applications reported for mechanical microsensors. New developments and the possibilities for routine work in the near future are also covered.

  9. Snow Micro-Structure Model

    SciTech Connect

    Micah Johnson, Andrew Slaughter

    2014-06-25

    PIKA is a MOOSE-based application for modeling micro-structure evolution of seasonal snow. The model will be useful for environmental, atmospheric, and climate scientists. Possible applications include application to energy balance models, ice sheet modeling, and avalanche forecasting. The model implements physics from published, peer-reviewed articles. The main purpose is to foster university and laboratory collaboration to build a larger multi-scale snow model using MOOSE. The main feature of the code is that it is implemented using the MOOSE framework, thus making features such as multiphysics coupling, adaptive mesh refinement, and parallel scalability native to the application. PIKA implements three equations: the phase-field equation for tracking the evolution of the ice-air interface within seasonal snow at the grain-scale; the heat equation for computing the temperature of both the ice and air within the snow; and the mass transport equation for monitoring the diffusion of water vapor in the pore space of the snow.

  10. Geometry optimization for micro-pressure sensor considering dynamic interference

    SciTech Connect

    Yu, Zhongliang; Zhao, Yulong Li, Lili; Tian, Bian; Li, Cun

    2014-09-15

    Presented is the geometry optimization for piezoresistive absolute micro-pressure sensor. A figure of merit called the performance factor (PF) is defined as a quantitative index to describe the comprehensive performances of a sensor including sensitivity, resonant frequency, and acceleration interference. Three geometries are proposed through introducing islands and sensitive beams into typical flat diaphragm. The stress distributions of sensitive elements are analyzed by finite element method. Multivariate fittings based on ANSYS simulation results are performed to establish the equations about surface stress, deflection, and resonant frequency. Optimization by MATLAB is carried out to determine the dimensions of the geometries. Convex corner undercutting is evaluated. Each PF of the three geometries with the determined dimensions is calculated and compared. Silicon bulk micromachining is utilized to fabricate the prototypes of the sensors. The outputs of the sensors under both static and dynamic conditions are tested. Experimental results demonstrate the rationality of the defined performance factor and reveal that the geometry with quad islands presents the highest PF of 210.947 Hz{sup 1/4}. The favorable overall performances enable the sensor more suitable for altimetry.

  11. Torque sensor having a spoked sensor element support structure

    NASA Technical Reports Server (NTRS)

    Lurie, Boris J. (Inventor); Schier, J. Alan (Inventor)

    1990-01-01

    Piezoelectric sensor devices are attached across pairs of circularly arranged spokes arrayed on the periphery of an annular ring. The sensor devices each include a preloaded steel ball mounting arrangement for mounting a piezoelectric sensor element. A first circular interface plate on one side of the sensor structure attaches to alternate one of the spokes, and a circular interface plate on the opposite side of the same diameter as the first interface plate attaches to the remaining spokes.

  12. Cobalt oxide nanosheet and CNT micro carbon monoxide sensor integrated with readout circuit on chip.

    PubMed

    Dai, Ching-Liang; Chen, Yen-Chi; Wu, Chyan-Chyi; Kuo, Chin-Fu

    2010-01-01

    The study presents a micro carbon monoxide (CO) sensor integrated with a readout circuit-on-a-chip manufactured by the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process and a post-process. The sensing film of the sensor is a composite cobalt oxide nanosheet and carbon nanotube (CoOOH/CNT) film that is prepared by a precipitation-oxidation method. The structure of the CO sensor is composed of a polysilicon resistor and a sensing film. The sensor, which is of a resistive type, changes its resistance when the sensing film adsorbs or desorbs CO gas. The readout circuit is used to convert the sensor resistance into the voltage output. The post-processing of the sensor includes etching the sacrificial layers and coating the sensing film. The advantages of the sensor include room temperature operation, short response/recovery times and easy post-processing. Experimental results show that the sensitivity of the CO sensor is about 0.19 mV/ppm, and the response and recovery times are 23 s and 34 s for 200 ppm CO, respectively.

  13. Study on the micro-heater geometry in In,2O3 micro electro mechanical systems gas sensor platforms and effects on NO2 gas detecting performances.

    PubMed

    Choi, Woo-Seok; Kim, Bum-Joon; Lee, Hoi-Jung; Choi, Jung-Woon; Kim, Si-Dong; Min, Nam-Ki

    2012-02-01

    Micro electro mechanical systems (MEMS) platforms for gas sensing devices with the co-planar type micro-heaters were designed, fabricated and its effects on the In2O3 gas sensors were investigated. Micro-heaters in MEMS gas sensor platforms were designed in the four-type heater patterns with different geometries. Electro-thermal characterizations showed that the designed platforms had highly thermal efficiency because the micro hot-plate structures were formed in the diaphragm and the thermal efficiencies were analyzed for all of 16 models and compared with each other, respectively. The designed micro-platforms were fabricated by MEMS process, and Indium oxide (In2O3) nanoparticles were synthesized by sol-gel process and dropped on the MEMS platforms for detecting the noxious oxide gas (NO2) Fabricated micro-platforms had a very low power consumption in the fabricated 16-type models, especially, the minimum power consumption was 41 mW at the operating temperature of 250 degrees C. After experiments on gas sensing characteristics to NO2 gases, fabricated In2O3 gas sensors had almost the same gas sensitivity (Rs) at the operation temperature of 250 degrees C. It is concluded that the micro-heater geometries, pattern shapes and sizes, can be influential on the power consumption of the devices and its gas sensing characteristics.

  14. Applications of micro/nanoparticles in microfluidic sensors: a review.

    PubMed

    Jiang, Yusheng; Wang, Hui; Li, Shunbo; Wen, Weijia

    2014-04-21

    This paper reviews the applications of micro/nanoparticles in microfluidics device fabrication and analytical processing. In general, researchers have focused on two properties of particles--electric behavior and magnetic behavior. The applications of micro/nanoparticles could be summarized on the chip fabrication level and on the processing level. In the fabrication of microfluidic chips (chip fabrication level), particles are good additives in polydimethylsiloxane (PDMS) to prepare conductive or magnetic composites which have wide applications in sensors, valves and actuators. On the other hand, particles could be manipulated according to their electric and magnetic properties under external electric and magnetic fields when they are travelling in microchannels (processing level). Researchers have made a great progress in preparing modified PDMS and investigating the behaviors of particles in microchannels. This article attempts to present a discussion on the basis of particles applications in microfluidics.

  15. Applications of Micro/Nanoparticles in Microfluidic Sensors: A Review

    PubMed Central

    Jiang, Yusheng; Wang, Hui; Li, Shunbo; Wen, Weijia

    2014-01-01

    This paper reviews the applications of micro/nanoparticles in microfluidics device fabrication and analytical processing. In general, researchers have focused on two properties of particles—electric behavior and magnetic behavior. The applications of micro/nanoparticles could be summarized on the chip fabrication level and on the processing level. In the fabrication of microfluidic chips (chip fabrication level), particles are good additives in polydimethylsiloxane (PDMS) to prepare conductive or magnetic composites which have wide applications in sensors, valves and actuators. On the other hand, particles could be manipulated according to their electric and magnetic properties under external electric and magnetic fields when they are travelling in microchannels (processing level). Researchers have made a great progress in preparing modified PDMS and investigating the behaviors of particles in microchannels. This article attempts to present a discussion on the basis of particles applications in microfluidics. PMID:24755517

  16. Thermal chip fabrication with arrays of sensors and heaters for micro-scale impingement cooling heat transfer analysis and measurements.

    PubMed

    Shen, C H; Gau, C

    2004-07-30

    The design and fabrication for a thermal chip with an array of temperature sensors and heaters for study of micro-jet impingement cooling heat transfer process are presented. This thermal chip can minimize the heat loss from the system to the ambient and provide a uniform heat flux along the wall, thus local heat transfer processes along the wall can be measured and obtained. The fabrication procedure presented can reach a chip yield of 100%, and every one of the sensors and heaters on the chip is in good condition. In addition, micro-jet impingement cooling experiments are performed to obtain the micro-scale local heat transfer Nusselt number along the wall. Flow visualization for the micro-impinging jet is also made. The experimental results indicate that both the micro-scale impinging jet flow structure and the heat transfer process along the wall is significantly different from the case of large-scale jet impingement cooling process.

  17. Micro Electro-Mechanical System (MEMS) Pressure Sensor for Footwear

    DOEpatents

    Kholwadwala, Deepesh K.; Rohrer, Brandon R.; Spletzer, Barry L.; Galambos, Paul C.; Wheeler, Jason W.; Hobart, Clinton G.; Givler, Richard C.

    2008-09-23

    Footwear comprises a sole and a plurality of sealed cavities contained within the sole. The sealed cavities can be incorporated as deformable containers within an elastic medium, comprising the sole. A plurality of micro electro-mechanical system (MEMS) pressure sensors are respectively contained within the sealed cavity plurality, and can be adapted to measure static and dynamic pressure within each of the sealed cavities. The pressure measurements can provide information relating to the contact pressure distribution between the sole of the footwear and the wearer's environment.

  18. Development of Magnetically Excited Flexural Plate Wave Devices for Implementation as Physical, Chemical, and Acoustic Sensors, and as Integrated Micro-Pumps for Sensored Systems

    NASA Astrophysics Data System (ADS)

    Schubert, W. K.; Mitchell, M. A.; Graf, D. C.; Shul, R. J.

    2002-05-01

    The magnetically excited flexural plate wave (mag-FPW) device has great promise as a versatile sensor platform. FPW's can have better sensitivity at lower operating frequencies than surface acoustic wave (SAW) devices. Lower operating frequency simplifies the control electronics and makes integration of sensor with electronics easier. Magnetic rather than piezoelectric excitation of the FPW greatly simplifies the device structure and processing by eliminating the need for piezoelectric thin films, also simplifying integration issues. The versatile mag-FPW resonator structure can potentially be configured to fulfill a number of critical functions in an autonomous sensored system. As a physical sensor, the device can be extremely sensitive to temperature, fluid flow, strain, acceleration and vibration. By coating the membrane with self-assembled monolayers (SAMs), or polymer films with selective absorption properties (originally developed for SAW sensors), the mass sensitivity of the FPW allows it to be used as biological or chemical sensors. Yet another critical need in autonomous sensor systems is the ability to pump fluid. FPW structures can be configured as micro-pumps. This report describes work done to develop mag-FPW devices as physical, chemical, and acoustic sensors, and as micro-pumps for both liquid and gas-phase analytes to enable new integrated sensing platform.

  19. MicroSensors Systems: detection of a dismounted threat

    NASA Astrophysics Data System (ADS)

    Shimazu, Ron N.; Berglund, Victor P.; Falkofske, Dwight M.; Krantz, Brian S.

    2004-11-01

    The MicroSensors Systems (MSS) Program is developing a layered sensor network to detect dismounted threats approaching high value assets. The MSS subsystem elements include sensitive receivers (capable of detecting<<1 Watt emissions in dense signal or degraded signal environments) and low power, miniature, disposable sensors (acoustic, magnetic, and infrared). A novel network protocol has been developed to reduce the network traffic resulting in conservation of system power and lower probability of detection and interception. The MSS program will provide unprecedented levels of real-time battlefield information, greatly enhancing combat situational awareness when integrated with the existing Command, Control, and Communications, Computers, Intelligence, Surveillance and Reconnaissance (C4ISR) infrastructure. This system will provide an important boost to realizing the information dominant, network-centric objective of Joint Vision 2020. The program has established two Centers of Excellence for Sensor Technology each of which is capable of designing and building next generation, networked microsensor systems. The Defense Microelectronics Activity has teamed with the Centers of Excellence and industry to preserve long-term Department of Defense access to key next generation manufacturing technologies.

  20. Microstructured optical fiber-based micro-cavity sensor for chemical detection

    NASA Astrophysics Data System (ADS)

    Kim, Bongkyun; Ahn, Jin-Chul; Chung, Phil-Sang; Chung, Youngjoo

    2014-02-01

    The studies on microstructured optical fibers (MOF) have drawn considerable interest and played an important role in many applications. MOFs provide unique optical properties and controllable modal properties because of their flexibilities on manipulation of the transmission spectrum and the waveguide dispersion properties. MOFs are especially useful for optical sensing applications because the micro-structured air channels in MOF can host various types of analytes such as liquids, gases, and chemical molecules. Recently, many studies have focused on the development of MOF-based optical sensors for various gases and chemical molecules. We propose a compact, and highly sensitive optical micro-cavity chemical sensor using microstructured fiber. The sensor probe is composed of a hollow optical fiber and end cleaved microstructured fiber with a solid core. The interference spectrum resulting from the reflected light at the silica and air interfaces changes when the micro-cavity is infiltrated with external chemical molecules. This structure enables the direct detection of chemical molecules such as volatile organic compounds (VOCs) without the introduction of any permeable material.

  1. An Asynchronous Multi-Sensor Micro Control Unit for Wireless Body Sensor Networks (WBSNs)

    PubMed Central

    Chen, Chiung-An; Chen, Shih-Lun; Huang, Hong-Yi; Luo, Ching-Hsing

    2011-01-01

    In this work, an asynchronous multi-sensor micro control unit (MCU) core is proposed for wireless body sensor networks (WBSNs). It consists of asynchronous interfaces, a power management unit, a multi-sensor controller, a data encoder (DE), and an error correct coder (ECC). To improve the system performance and expansion abilities, the asynchronous interface is created for handshaking different clock domains between ADC and RF with MCU. To increase the use time of the WBSN system, a power management technique is developed for reducing power consumption. In addition, the multi-sensor controller is designed for detecting various biomedical signals. To prevent loss error from wireless transmission, use of an error correct coding technique is important in biomedical applications. The data encoder is added for lossless compression of various biomedical signals with a compression ratio of almost three. This design is successfully tested on a FPGA board. The VLSI architecture of this work contains 2.68-K gate counts and consumes power 496-μW at 133-MHz processing rate by using TSMC 0.13-μm CMOS process. Compared with the previous techniques, this work offers higher performance, more functions, and lower hardware cost than other micro controller designs. PMID:22164000

  2. An asynchronous multi-sensor micro control unit for wireless body sensor networks (WBSNs).

    PubMed

    Chen, Chiung-An; Chen, Shih-Lun; Huang, Hong-Yi; Luo, Ching-Hsing

    2011-01-01

    In this work, an asynchronous multi-sensor micro control unit (MCU) core is proposed for wireless body sensor networks (WBSNs). It consists of asynchronous interfaces, a power management unit, a multi-sensor controller, a data encoder (DE), and an error correct coder (ECC). To improve the system performance and expansion abilities, the asynchronous interface is created for handshaking different clock domains between ADC and RF with MCU. To increase the use time of the WBSN system, a power management technique is developed for reducing power consumption. In addition, the multi-sensor controller is designed for detecting various biomedical signals. To prevent loss error from wireless transmission, use of an error correct coding technique is important in biomedical applications. The data encoder is added for lossless compression of various biomedical signals with a compression ratio of almost three. This design is successfully tested on a FPGA board. The VLSI architecture of this work contains 2.68-K gate counts and consumes power 496-μW at 133-MHz processing rate by using TSMC 0.13-μm CMOS process. Compared with the previous techniques, this work offers higher performance, more functions, and lower hardware cost than other micro controller designs.

  3. Development of micro-heaters with optimized temperature compensation design for gas sensors.

    PubMed

    Hwang, Woo-Jin; Shin, Kyu-Sik; Roh, Ji-Hyoung; Lee, Dae-Sung; Choa, Sung-Hoon

    2011-01-01

    One of the key components of a chemical gas sensor is a MEMS micro-heater. Micro-heaters are used in both semiconductor gas sensors and NDIR gas sensors; however they each require different heat dissipation characteristics. For the semiconductor gas sensors, a uniform temperature is required over a wide area of the heater. On the other hand, for the NDIR gas sensor, the micro-heater needs high levels of infrared radiation in order to increase sensitivity. In this study, a novel design of a poly-Si micro-heater is proposed to improve the uniformity of heat dissipation on the heating plate. Temperature uniformity of the micro-heater is achieved by compensating for the variation in power consumption around the perimeter of the heater. With the power compensated design, the uniform heating area is increased by 2.5 times and the average temperature goes up by 40 °C. Therefore, this power compensated micro-heater design is suitable for a semiconductor gas sensor. Meanwhile, the poly-Si micro-heater without compensation shows a higher level of infrared radiation under equal power consumption conditions. This indicates that the micro-heater without compensation is more suitable for a NDIR gas sensor. Furthermore, the micro-heater shows a short response time of less than 20 ms, indicating a very high efficiency of pulse driving.

  4. Micro-machined millimeter wave sensor array for FM radar application

    NASA Astrophysics Data System (ADS)

    Trontelj, Janez; Sešek, Aleksander

    2012-10-01

    The objective of this work was to create a low cost sensor array that operates at room temperature for millimeter wave applications and could be used for FM radars and various heterodyne receivers. The selected technology was silicon wafer micromachining allowing the creation of microstructures on silicon membranes using different metal layers. The technology used allowed submicron dimensions for a photolithography pattern and thin membranes down to a few micrometers. One of the most critical requirements for the sensor was to achieve a high signal-to-noise ratio and a high bandwidth for a mixed frequency. The sensor is a titanium-based micro-bolometer connected to the micro-antenna which is integrated with the bolometer. The results are very promising. The measured NEP is below 5pW/√Hz and the sensitivity is close to 1000 V/W. In the paper the antenna - bolometer sensor microstructure is analyzed. Theoretical analysis and design guidelines for the bolometer itself are discussed. Simulation results of the bolometer and antenna show very close matching to the measured results. Characterization measurements were performed, and thermal behavior of microbolometer structure was simulated and measured. The measurement results are presented for THz FM radar different targets, and a technology demonstrator is also described.

  5. Further Structural Intelligence for Sensors Cluster Technology in Manufacturing

    PubMed Central

    Mekid, Samir

    2006-01-01

    With the ever increasing complex sensing and actuating tasks in manufacturing plants, intelligent sensors cluster in hybrid networks becomes a rapidly expanding area. They play a dominant role in many fields from macro and micro scale. Global object control and the ability to self organize into fault-tolerant and scalable systems are expected for high level applications. In this paper, new structural concepts of intelligent sensors and networks with new intelligent agents are presented. Embedding new functionalities to dynamically manage cooperative agents for autonomous machines are interesting key enabling technologies most required in manufacturing for zero defects production.

  6. Low-power-Consumption metal oxide NO2 gas sensor based on micro-heater and screen printing technology.

    PubMed

    Moon, S E; Lee, H K; Choi, N J; Lee, J; Yang, W S; Kim, J; Jong, J J; Yoo, D J

    2012-07-01

    An NO2 micro gas sensor was fabricated based on a micro-heater using tin oxide nano-powders for effective gas detection and monitoring system with low power consumption and high sensitivity. The processes of the fabrication were acceptable to the conventional CMOS processes for mass-production. Semiconducting SnO2 nano-powders were synthesized via the co-precipitation method; and to increase the sensitivity of the NO2 gas rare metal dopants were added. In the structure of the micro-heater, the resistances of two semi-circular Pt heaters were connected to the spreader for thermal uniformity. The resistance of each heater becomes an electrically equal Wheatstone-bridge, which was divided in half by the heat spreading structure. Based on the aforementioned design, a low-power-consumption micro-heater was fabricated using the CMOS-compatible MEMS processes. A bridge-type micro-heater based on the Si substrate was fabricated via surface micro-machining. The NO2 sensing properties of a screen-printed tin oxide thick film device were measured The micro gas sensors showed substantial sensitivity down to 0.5 ppm NO2 at a low power consumption (34.2 mW).

  7. Design and characterization of a silicon piezoresistive three-axial force sensor for micro-flapping wing MAV applications

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Truong, Van T.; Lua, Kim B.; Kumar, A. S.; Lim, Tee Tai; Yeo, Khoon Seng; Zhou, Guangya

    2015-03-01

    This paper describes the design and electro-mechanical characterizations of a three-axial micro piezoresistive force sensor fabricated by microelectromechanical systems (MEMS) technologies. This is the first three-axial MEMS micro force sensor applied to the study of Micro Aerial Vehicle (MAV) aerodynamics. A standard dry etching fabrication process using Silicon On Insulator (SOI) wafer is employed to fabricate the multi-axis sensors. Conventional cross-beam structure is employed. There are eight piezoresistors on the beams, and each of the silicon strain gauge size is 15 μm in width, and between 400 and 500 μm in length. The Finite Element Method (FEM) analysis for confirming the piezoresistors attachment locations is performed. The miniaturized force sensor (11×11 mm2) is attached at the wing base of a micro flapping wing system (MAV, 70×30 mm2 ) by a short pillar. The sensor is designed to detect the dynamic drag force and lift force generated by a single wing under a moderate flapping frequency (5~10Hz) simultaneously. The characterizations are experimentally investigated. The sensor should be stiff enough to withstand the high inertial force (200 millinewton) and also has high resolution to detect the minimal force correctly. Measurements show that the resolution is on the order of a millinewton. High linearity and low hysteresis under normal forces and tangential forces are demonstrated by applying forces from 0 to 0.1 N. The micro flapping wing mechanism and the assembly of wing and sensor are also discussed in this paper.

  8. The investigation of liquid analysis method based on fiber micro-drop sensor

    NASA Astrophysics Data System (ADS)

    Sun, Weimin; Li, Xiaomei; Zeng, Youmin

    2007-01-01

    A portable and practical fiber micro-drop sensor, with which can determine the refractive index and the concentration of the liquid, has be designed and realized. The advantages of this sensors combines simplicity of structure, facility of operation, wide range of measurement and low price. Liquid drops formed at the tip of a liquid sensing head are measured by a fiber sensor. The fiber sensor works as follows: infrared light source is injected into the drop through an optical fiber and the total internal reflections and absorptions are detected by a photo detector. A drop speed independent one-dimensional waveform, fiber fingerprint drop trace (FFDT), is generated. Liquid surface tension, refractive index and dielectric constant can be estimated from the fingerprint. For the effective use of the sensor, a new on-line method of liquid drop analysis is proposed, which is used for liquid discrimination with the orderliness of the fiber fingerprint drop trace. To compare two fingerprints effectively, signal analysis is required. Comparing fiber fingerprint drop trace, which might cause peaks and valleys in the trace at almost the same wavelet, digital signals process is more intuitionist. Analyzing every part of the fingerprint drop trace with impactful signal analysis method, as Fast Fourier Transform algorithm and correlative analysis, some orderliness can be revealed. Colligating the orderliness, we can discriminate all kinds of liquids or their characteristic parameters, such as liquid concentration, refractive index and so on.

  9. 3D printing of nano- and micro-structures

    NASA Astrophysics Data System (ADS)

    Ramasamy, Mouli; Varadan, Vijay K.

    2016-04-01

    Additive manufacturing or 3D printing techniques are being vigorously investigated as a replacement to the traditional and conventional methods in fabrication to bring forth cost and time effective approaches. Introduction of 3D printing has led to printing micro and nanoscale structures including tissues and organelles, bioelectric sensors and devices, artificial bones and transplants, microfluidic devices, batteries and various other biomaterials. Various microfabrication processes have been developed to fabricate micro components and assemblies at lab scale. 3D Fabrication processes that can accommodate the functional and geometrical requirements to realize complicated structures are becoming feasible through advances in additive manufacturing. This advancement could lead to simpler development mechanisms of novel components and devices exhibiting complex features. For instance, development of microstructure electrodes that can penetrate the epidermis of the skin to collect the bio potential signal may prove very effective than the electrodes that measure signal from the skin's surface. The micro and nanostructures will have to possess extraordinary material and mechanical properties for its dexterity in the applications. A substantial amount of research being pursued on stretchable and flexible devices based on PDMA, textiles, and organic electronics. Despite the numerous advantages these substrates and techniques could solely offer, 3D printing enables a multi-dimensional approach towards finer and complex applications. This review emphasizes the use of 3D printing to fabricate micro and nanostructures for that can be applied for human healthcare.

  10. High-Frequency Fiber-Optic Ultrasonic Sensor Using Air Micro-Bubble for Imaging of Seismic Physical Models.

    PubMed

    Gang, Tingting; Hu, Manli; Rong, Qiangzhou; Qiao, Xueguang; Liang, Lei; Liu, Nan; Tong, Rongxin; Liu, Xiaobo; Bian, Ce

    2016-12-14

    A micro-fiber-optic Fabry-Perot interferometer (FPI) is proposed and demonstrated experimentally for ultrasonic imaging of seismic physical models. The device consists of a micro-bubble followed by the end of a single-mode fiber (SMF). The micro-structure is formed by the discharging operation on a short segment of hollow-core fiber (HCF) that is spliced to the SMF. This micro FPI is sensitive to ultrasonic waves (UWs), especially to the high-frequency (up to 10 MHz) UW, thanks to its ultra-thin cavity wall and micro-diameter. A side-band filter technology is employed for the UW interrogation, and then the high signal-to-noise ratio (SNR) UW signal is achieved. Eventually the sensor is used for lateral imaging of the physical model by scanning UW detection and two-dimensional signal reconstruction.

  11. High-Frequency Fiber-Optic Ultrasonic Sensor Using Air Micro-Bubble for Imaging of Seismic Physical Models

    PubMed Central

    Gang, Tingting; Hu, Manli; Rong, Qiangzhou; Qiao, Xueguang; Liang, Lei; Liu, Nan; Tong, Rongxin; Liu, Xiaobo; Bian, Ce

    2016-01-01

    A micro-fiber-optic Fabry-Perot interferometer (FPI) is proposed and demonstrated experimentally for ultrasonic imaging of seismic physical models. The device consists of a micro-bubble followed by the end of a single-mode fiber (SMF). The micro-structure is formed by the discharging operation on a short segment of hollow-core fiber (HCF) that is spliced to the SMF. This micro FPI is sensitive to ultrasonic waves (UWs), especially to the high-frequency (up to 10 MHz) UW, thanks to its ultra-thin cavity wall and micro-diameter. A side-band filter technology is employed for the UW interrogation, and then the high signal-to-noise ratio (SNR) UW signal is achieved. Eventually the sensor is used for lateral imaging of the physical model by scanning UW detection and two-dimensional signal reconstruction. PMID:27983639

  12. Silicon micro sensors as integrated readout platform for colorimetric and fluorescence based opto-chemical transducers

    NASA Astrophysics Data System (ADS)

    Will, Matthias; Martan, Tomas; Brodersen, Olaf

    2011-09-01

    Opto-chemical transducer almost offers unlimited possibilities for detection of physical quantities. New technologies and research show a steady increasing of publications in the area of sensoric principles. For transfer to real world applications the optical response has to be converted into an electrical signal. An exceptional opto chemical transducer loses the attraction if complex and expensive instruments for analysis are requires. Therefore, the readout system must be very compact and producible for low cost. In this presentation, the technology platform as a solution for these problems will be presented. We combine micro structuring of silicon, photodiode fabrication, chip in chip mounting and novel assembly technologies for creation of a flexible sensor platform. This flexible combination of technologies allows fabricating a family of planar optical remission sensors. With variation of design and modifications, we are able to detect colorimetric, fluorescent properties of an sensitive layer attached on the sensor surface. In our sensor with typical size of 6mm x 6mm x 1mm different emitting sources based on LED's or laser diodes, multiple detection cannels for the remitted light and also measurement of temperature are included. Based on these sensors we proof the concept by demonstrating sensors for oxygen, carbon dioxide and ammonia based on colorimetric and fluorescent changes in the transducer layer. In both configurations, LED's irradiated the sensitive polymer layer through a transparent substrate. The absorption or fluorescence properties of dyed polymer are changed by the chemical reaction and light response is detected by PIN diodes. The signal shift is analyzed by using a computer controlled evaluation board of own construction. Accuracy and reliability of the remission sensor system were verified and the whole sensor system was experimentally tested in the range of concentrations from 50 ppm up to 100 000 ppm for CO2 and O2 Furthermore, we develop

  13. Silicon micro sensors as integrated readout platform for colorimetric and fluorescence based opto-chemical transducers

    NASA Astrophysics Data System (ADS)

    Will, Matthias; Martan, Tomas; Brodersen, Olaf

    2012-02-01

    Opto-chemical transducer almost offers unlimited possibilities for detection of physical quantities. New technologies and research show a steady increasing of publications in the area of sensoric principles. For transfer to real world applications the optical response has to be converted into an electrical signal. An exceptional opto chemical transducer loses the attraction if complex and expensive instruments for analysis are requires. Therefore, the readout system must be very compact and producible for low cost. In this presentation, the technology platform as a solution for these problems will be presented. We combine micro structuring of silicon, photodiode fabrication, chip in chip mounting and novel assembly technologies for creation of a flexible sensor platform. This flexible combination of technologies allows fabricating a family of planar optical remission sensors. With variation of design and modifications, we are able to detect colorimetric, fluorescent properties of an sensitive layer attached on the sensor surface. In our sensor with typical size of 6mm x 6mm x 1mm different emitting sources based on LED's or laser diodes, multiple detection cannels for the remitted light and also measurement of temperature are included. Based on these sensors we proof the concept by demonstrating sensors for oxygen, carbon dioxide and ammonia based on colorimetric and fluorescent changes in the transducer layer. In both configurations, LED's irradiated the sensitive polymer layer through a transparent substrate. The absorption or fluorescence properties of dyed polymer are changed by the chemical reaction and light response is detected by PIN diodes. The signal shift is analyzed by using a computer controlled evaluation board of own construction. Accuracy and reliability of the remission sensor system were verified and the whole sensor system was experimentally tested in the range of concentrations from 50 ppm up to 100 000 ppm for CO2 and O2 Furthermore, we develop

  14. Global Environmental Micro Sensors Test Operations in the Natural Environment

    NASA Technical Reports Server (NTRS)

    Adams, Mark L.; Buza, Matthew; Manobianco, John; Merceret, Francis J.

    2007-01-01

    ENSCO, Inc. is developing an innovative atmospheric observing system known as Global Environmental Micro Sensors (GEMS). The GEMS concept features an integrated system of miniaturized in situ, airborne probes measuring temperature, relative humidity, pressure, and vector wind velocity. In order for the probes to remain airborne for long periods of time, their design is based on a helium-filled super-pressure balloon. The GEMS probes are neutrally buoyant and carried passively by the wind at predetermined levels. Each probe contains onboard satellite communication, power generation, processing, and geolocation capabilities. ENSCO has partnered with the National Aeronautics and Space Administration's Kennedy Space Center (KSC) for a project called GEMS Test Operations in the Natural Environment (GEMSTONE) that will culminate with limited prototype flights of the system in spring 2007. By leveraging current advances in micro and nanotechnology, the probe mass, size, cost, and complexity can be reduced substantially so that large numbers of probes could be deployed routinely to support ground, launch, and landing operations at KSC and other locations. A full-scale system will improve the data density for the local initialization of high-resolution numerical weather prediction systems by at least an order of magnitude and provide a significantly expanded in situ data base to evaluate launch commit criteria and flight rules. When applied to launch or landing sites, this capability will reduce both weather hazards and weather-related scrubs, thus enhancing both safety and cost-avoidance for vehicles processed by the Shuttle, Launch Services Program, and Constellation Directorates. The GEMSTONE project will conclude with a field experiment in which 10 to 15 probes are released over KSC in east central Florida. The probes will be neutrally buoyant at different altitudes from 500 to 3000 meters and will report their position, speed, heading, temperature, humidity, and

  15. Structure and yarn sensor for fabric

    DOEpatents

    Mee, David K.; Allgood, Glenn O.; Mooney, Larry R.; Duncan, Michael G.; Turner, John C.; Treece, Dale A.

    1998-01-01

    A structure and yarn sensor for fabric directly determines pick density in a fabric thereby allowing fabric length and velocity to be calculated from a count of the picks made by the sensor over known time intervals. The structure and yarn sensor is also capable of detecting full length woven defects and fabric. As a result, an inexpensive on-line pick (or course) density measurement can be performed which allows a loom or knitting machine to be adjusted by either manual or automatic means to maintain closer fiber density tolerances. Such a sensor apparatus dramatically reduces fabric production costs and significantly improves fabric consistency and quality for woven or knitted fabric.

  16. Sensitivity enhancement of a micro-scale biomimetic tactile sensor with epidermal ridges

    NASA Astrophysics Data System (ADS)

    Zhang, Yuhua

    2010-08-01

    A microscale biomimetic tactile sensor with epidermal ridges is proposed to enhance the sensitivity of force detection. Guided by the principles of the human tactile perception mechanism, specifically the epidermal ridges, artificial epidermal ridges made of polydimethylsiloxane (PDMS) were designed and placed on micro-fabricated metal strain gauge arrays. A polyimide layer was fabricated to facilitate attachment between the metal and PDMS, so that patterned copper could be deposited on the polyimide to function as the strain gauges. The aspect ratio of the artificial epidermal ridges was optimized using material stability calculations and finite element method (FEM) simulations, and the optimal structure obtained was 400 µm in width and 110 µm in height. Experiments verified the effectiveness of enhancing the sensitivity of such a tactile sensor with the artificial epidermal ridges, in that the outputs of the strain gauges were 1.8 times more sensitive than those of a tactile sensor without ridges. The proposed artificial epidermal ridges are readily applicable to any developed tactile sensors for performance enhancement.

  17. Discrete shaped strain sensors for intelligent structures

    NASA Technical Reports Server (NTRS)

    Andersson, Mark S.; Crawley, Edward F.

    1992-01-01

    Design of discrete, highly distributed sensor systems for intelligent structures has been studied. Data obtained indicate that discrete strain-averaging sensors satisfy the functional requirements for distributed sensing of intelligent structures. Bartlett and Gauss-Hanning sensors, in particular, provide good wavenumber characteristics while meeting the functional requirements. They are characterized by good rolloff rates and positive Fourier transforms for all wavenumbers. For the numerical integration schemes, Simpson's rule is considered to be very simple to implement and consistently provides accurate results for five sensors or more. It is shown that a sensor system that satisfies the functional requirements can be applied to a structure that supports mode shapes with purely sinusoidal curvature.

  18. Selected examples of intelligent (micro) sensor systems: state-of-the-art and tendencies

    NASA Astrophysics Data System (ADS)

    Hauptmann, Peter R.

    2006-03-01

    The capability of intelligent sensors to have more intelligence built into them continues to drive their application in areas including automotive, aerospace and defense, industrial, intelligent house and wear, medical and homeland security. In principle it is difficult to overestimate the importance of intelligent (micro) sensors or sensor systems within advanced societies but one characteristic feature is the global market for sensors, which is now about 20 billion annually. Therefore sensors or sensor systems play a dominant role in many fields from the macro sensor in manufacturing industry down to the miniaturized sensor for medical applications. The diversity of sensors precludes a complete description of the state-of-the-art; selected examples will illustrate the current situation. MEMS (microelectromechanical systems) devices are of special interest in the context of micro sensor systems. In past the main requirements of a sensor were in terms of metrological performance. The electrical (or optical) signal produced by the sensor needed to match the measure relatively accurately. Such basic functionality is no longer sufficient. Data processing near the sensor, the extraction of more information than just the direct sensor information by signal analysis, system aspects and multi-sensor information are the new demands. A shifting can be observed away from aiming to design perfect single-function transducers and towards the utilization of system-based sensors as system components. In the ideal case such systems contain sensors, actuators and electronics. They can be realized in monolithic, hybrid or discrete form—which kind is used depends on the application. In this article the state-of-the-art of intelligent sensors or sensor systems is reviewed using selected examples. Future trends are deduced.

  19. Micro-LiDAR velocity, temperature, density, concentration sensor

    NASA Technical Reports Server (NTRS)

    Danehy, Paul M. (Inventor); Dorrington, Adrian A. (Inventor)

    2010-01-01

    A light scatter sensor includes a sensor body in which are positioned a plurality of optical fibers. The sensor body includes a surface, in one end of each of the optical fibers terminates at the surface of the sensor body. One of the optical fibers is an illumination fiber for emitting light. A plurality of second optical fibers are collection fibers for collecting scattered light signals. A light sensor processor is connected to the collection fibers to detect the scattered light signals.

  20. Micro structured glass optics - basics and benefits

    NASA Astrophysics Data System (ADS)

    Geyer, Ulf; Paßlick, Christian; Heßling, Thomas; Hellwig, Ansgar; Hübner, Marc C.

    2016-09-01

    Today's trends in illumination engineering clearly turn towards high power LED applications with a precisely controlled light output. The first requires glass optics which will withstand the increasing temperature load and lumen output of LEDs. The second requires tight control of production tolerances and defined surface structuring. Especially the surface structure - which can be realized for example as micro lens arrays - is of increasing importance. Using two different fabrication techniques we investigated the implementation of micro surface textures on glass optics. The first method uses directly molded glass from the liquid phase while the second is an imprint process. For both methods we determined the minimum replicable feature size and found current limits of only 50 μm for the imprint process.

  1. Pulse-driven micro gas sensor fitted with clustered Pd/SnO2 nanoparticles.

    PubMed

    Suematsu, Koichi; Shin, Yuka; Ma, Nan; Oyama, Tokiharu; Sasaki, Miyuki; Yuasa, Masayoshi; Kida, Tetsuya; Shimanoe, Kengo

    2015-08-18

    Real-time monitoring of specific gas concentrations with a compact and portable gas sensing device is required to sense potential health risk and danger from toxic gases. For such purposes, we developed an ultrasmall gas sensor device, where a micro sensing film was deposited on a micro heater integrated with electrodes fabricated by the microelectromechanical system (MEMS) technology. The developed device was operated in a pulse-heating mode to significantly reduce the heater power consumption and make the device battery-driven and portable. Using clustered Pd/SnO2 nanoparticles, we succeeded in introducing mesopores ranging from 10 to 30 nm in the micro gas sensing film (area: ϕ 150 μm) to detect large volatile organic compounds (VOCs). The micro sensor showed quick, stable, and high sensor responses to toluene at ppm (parts per million) concentrations at 300 °C even by operating the micro heater in a pulse-heating mode where switch-on and -off cycles were repeated at one-second intervals. The high performance of the micro sensor should result from the creation of efficient diffusion paths decorated with Pd sensitizers by using the clustered Pd/SnO2 nanoparticles. Hence we demonstrate that our pulse-driven micro sensor using nanostructured oxide materials holds promise as a battery-operable, portable gas sensing device.

  2. Applications of optical micro-ring and micro-disk resonators as physical, chemical, and biological sensors

    NASA Astrophysics Data System (ADS)

    Bhola, Bipin

    This dissertation presents the applications of optical micro-ring and micro-disk resonators as various sensors in physical, chemical, and biological applications. This work describes the functioning of 5 different sensors and suggests ways for optimizing the performance of each of them. All of these sensors work on the principle of shift in the resonance wavelength of the micro-ring or the micro-disk in response to an external physical, chemical or biological perturbation. The first portion describes the functioning of a ring resonator device and details the various parameters which are important in sensing applications. Then a strain sensor, an accelerometer, and a humidity sensor based on polymer micro-ring resonator are described. The strain sensor has a sensitivity of 0.32pm/muε and a dynamic range of 17000muε, the accelerometer has a sensitivity of 31pm/g and a dynamic range of +/-7g, whereas, the humidity sensor has a sensitivity of 16pm/%RH and a dynamic range of 72%. The dependency of each of their sensitivities and dynamic ranges on various geometrical parameters are also discussed. The response time of the humidity sensor was reduced to less than 200ms which enables us to utilize this device as a human breathing monitor in hospitals. The second portion of the thesis, discusses the possible incorporation of ultra-high-Q silica micro-disk resonators, developed at the Jet Propulsion Laboratory by Mr. Thanh M. Le, into various sensing devices. This device is first proposed as a biosensor for detecting trace amounts of specific biomolecules. The first experiments are performed for developing the silica micro-disk as a biosensor. In this experiment, the sensitivity of the micro-disk as a function of change in refractive index of the surrounding medium is demonstrated. The observed sensitivity is 11.82nm/RIU (Refractive Index Units). Then, the possibility of using this device as a specific biosensor is explored. The method for surface functionalization of the

  3. A thermal-driven silicon micro xy-stage integrated with piezoresistive sensors for nano-positioning

    NASA Astrophysics Data System (ADS)

    Choi, Young-Soo; Zhang, Yan; Lee, Dong-Weon

    2012-05-01

    This paper describes a novel micro xy-stage, driven by double-hot arm horizontal thermal micro-actuators integrated with a piezoresistive sensor (PS) for low-voltage operation and precise control. This micro xy-stage structure is linked with chevron beams and optimized to amplify the displacement generated by the micro-actuators that provide a pull force to the movable platform. The PS employed for in situ displacement detection and feedback control is fabricated at the base of a cold arm, which minimizes the influence of temperature change induced by electro-thermal heating. The micro xy-stage structure is defined through the use of a simple micromachining process, released by backside wet etching with a special tool. For an input power of approximately 44 mW, each chevron actuator provides about 16 µm and the total displacement of the platform is close to 32 µm. The sensitivity of the PS is better than 1 mV µm-1, obtained from the amplified voltage output of the Wheatstone bridge circuit. The potential applications of the proposed micro xy-stage lie in micro- or nano-manipulation, as well as the positioning of ultra-small objects in nanotechnology.

  4. Model-based Processing of Micro-cantilever Sensor Arrays

    SciTech Connect

    Tringe, J W; Clague, D S; Candy, J V; Lee, C L; Rudd, R E; Burnham, A K

    2004-11-17

    We develop a model-based processor (MBP) for a micro-cantilever array sensor to detect target species in solution. After discussing the generalized framework for this problem, we develop the specific model used in this study. We perform a proof-of-concept experiment, fit the model parameters to the measured data and use them to develop a Gauss-Markov simulation. We then investigate two cases of interest: (1) averaged deflection data, and (2) multi-channel data. In both cases the evaluation proceeds by first performing a model-based parameter estimation to extract the model parameters, next performing a Gauss-Markov simulation, designing the optimal MBP and finally applying it to measured experimental data. The simulation is used to evaluate the performance of the MBP in the multi-channel case and compare it to a ''smoother'' (''averager'') typically used in this application. It was shown that the MBP not only provides a significant gain ({approx} 80dB) in signal-to-noise ratio (SNR), but also consistently outperforms the smoother by 40-60 dB. Finally, we apply the processor to the smoothed experimental data and demonstrate its capability for chemical detection. The MBP performs quite well, though it includes a correctable systematic bias error. The project's primary accomplishment was the successful application of model-based processing to signals from micro-cantilever arrays: 40-60 dB improvement vs. the smoother algorithm was demonstrated. This result was achieved through the development of appropriate mathematical descriptions for the chemical and mechanical phenomena, and incorporation of these descriptions directly into the model-based signal processor. A significant challenge was the development of the framework which would maximize the usefulness of the signal processing algorithms while ensuring the accuracy of the mathematical description of the chemical-mechanical signal. Experimentally, the difficulty was to identify and characterize the non

  5. Phase coded, micro-power impulse radar motion sensor

    DOEpatents

    McEwan, Thomas E.

    1996-01-01

    A motion sensing, micro-power impulse radar MIR impresses on the transmitted signal, or the received pulse timing signal, one or more frequencies lower than the pulse repetition frequency, that become intermediate frequencies in a "IF homodyne" receiver. Thus, many advantages of classical RF receivers can be thereby be realized with ultra-wide band radar. The sensor includes a transmitter which transmits a sequence of electromagnetic pulses in response to a transmit timing signal at a nominal pulse repetition frequency. A receiver samples echoes of the sequence of electromagnetic pulses from objects within the field with controlled timing, in response to a receive timing signal, and generates a sample signal in response to the samples. A timing circuit supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver. The relative timing of the transmit timing signal and the receive timing signal is modulated between a first relative delay and a second relative delay at an intermediate frequency, causing the receiver to sample the echoes such that the time between transmissions of pulses in the sequence and samples by the receiver is modulated at the intermediate frequency. Modulation may be executed by modulating the pulse repetition frequency which drives the transmitter, by modulating the delay circuitry which controls the relative timing of the sample strobe, or by modulating amplitude of the transmitted pulses. The electromagnetic pulses will have a nominal center frequency related to pulse width, and the first relative delay and the second relative delay between which the timing signals are modulated, differ by less than the nominal pulse width, and preferably by about one-quarter wavelength at the nominal center frequency of the transmitted pulses.

  6. Phase coded, micro-power impulse radar motion sensor

    DOEpatents

    McEwan, T.E.

    1996-05-21

    A motion sensing, micro-power impulse radar MIR impresses on the transmitted signal, or the received pulse timing signal, one or more frequencies lower than the pulse repetition frequency, that become intermediate frequencies in a ``IF homodyne`` receiver. Thus, many advantages of classical RF receivers can be thereby be realized with ultra-wide band radar. The sensor includes a transmitter which transmits a sequence of electromagnetic pulses in response to a transmit timing signal at a nominal pulse repetition frequency. A receiver samples echoes of the sequence of electromagnetic pulses from objects within the field with controlled timing, in response to a receive timing signal, and generates a sample signal in response to the samples. A timing circuit supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver. The relative timing of the transmit timing signal and the receive timing signal is modulated between a first relative delay and a second relative delay at an intermediate frequency, causing the receiver to sample the echoes such that the time between transmissions of pulses in the sequence and samples by the receiver is modulated at the intermediate frequency. Modulation may be executed by modulating the pulse repetition frequency which drives the transmitter, by modulating the delay circuitry which controls the relative timing of the sample strobe, or by modulating amplitude of the transmitted pulses. The electromagnetic pulses will have a nominal center frequency related to pulse width, and the first relative delay and the second relative delay between which the timing signals are modulated, differ by less than the nominal pulse width, and preferably by about one-quarter wavelength at the nominal center frequency of the transmitted pulses. 5 figs.

  7. Micro-and Nano-Optomechanical Devices for Sensors, Oscillators, and Photonics

    DTIC Science & Technology

    2015-10-26

    AFRL-AFOSR-VA-TR-2015-0345 (MICRO-AND NANO-OPTOMECHANICAL DEVICES FOR SENSORS , OSCILLATORS, AND PHOTONICS Oskar Painter CALIFORNIA INSTITUTE OF...DEVICES FOR SENSORS , OSCILLATORS, AND PHOTONICS 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-10-1-0284 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S...coupling between light and mechanical motion could be realized via radiation pressure. Application of these devices to mechanical sensors , microwave

  8. Micro optical fiber light source and sensor and method of fabrication thereof

    DOEpatents

    Kopelman, Raoul; Tan, Weihong; Shi, Zhong-You

    1997-01-01

    This invention relates generally to the development of and a method of fabricating a fiber optic micro-light source and sensor (50). An optical fiber micro-light source (50) is presented whose aperture is extremely small yet able to act as an intense light source. Light sources of this type have wide ranging applications, including use as micro-sensors (22) in NSOM. Micro-sensor light sources have excellent detection limits as well as photo stability, reversibility, and millisecond response times. Furthermore, a method for manufacturing a micro optical fiber light source is provided. It involves the photo-chemical attachment of an optically active material onto the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture. More specifically, photopolymerization has been applied as a means to photo-chemically attach an optically active material (60). This process allows significant control of the size of the micro light source (50). Furthermore, photo-chemically attaching an optically active material (60) enables the implementation of the micro-light source in a variety of sensor applications.

  9. Micro optical fiber light source and sensor and method of fabrication thereof

    DOEpatents

    Kopelman, R.; Tan, W.; Shi, Z.Y.

    1997-05-06

    This invention relates generally to the development of and a method of fabricating a fiber optic micro-light source and sensor. An optical fiber micro-light source is presented whose aperture is extremely small yet able to act as an intense light source. Light sources of this type have wide ranging applications, including use as micro-sensors in NSOM. Micro-sensor light sources have excellent detection limits as well as photo stability, reversibility, and millisecond response times. Furthermore, a method for manufacturing a micro optical fiber light source is provided. It involves the photo-chemical attachment of an optically active material onto the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture. More specifically, photopolymerization has been applied as a means to photo-chemically attach an optically active material. This process allows significant control of the size of the micro light source. Furthermore, photo-chemically attaching an optically active material enables the implementation of the micro-light source in a variety of sensor applications. 10 figs.

  10. Piezoelectric Sensor Evaluation for Structural Health Monitoring of Cryogenic Structures

    NASA Technical Reports Server (NTRS)

    Lassiter, John; Engberg, Robert

    2005-01-01

    This viewgraph presentation provides an overview of Structural Health Monitoring (SHM), and profiles piezoelectric sensors useful for SHM of cryogenic structures. The presentation also profiles impedance tests and other SHM tests conducted at Marshall Space Flight Center (MSFC).

  11. Photonic Low Cost Micro-Sensor for in-Line Wear Particle Detection in Flowing Lube Oils

    PubMed Central

    Mabe, Jon; Zubia, Joseba; Gorritxategi, Eneko

    2017-01-01

    The presence of microscopic particles in suspension in industrial fluids is often an early warning of latent or imminent failures in the equipment or processes where they are being used. This manuscript describes work undertaken to integrate different photonic principles with a micro- mechanical fluidic structure and an embedded processor to develop a fully autonomous wear debris sensor for in-line monitoring of industrial fluids. Lens-less microscopy, stroboscopic illumination, a CMOS imager and embedded machine vision technologies have been merged to develop a sensor solution that is able to detect and quantify the number and size of micrometric particles suspended in a continuous flow of a fluid. A laboratory test-bench has been arranged for setting up the configuration of the optical components targeting a static oil sample and then a sensor prototype has been developed for migrating the measurement principles to real conditions in terms of operating pressure and flow rate of the oil. Imaging performance is quantified using micro calibrated samples, as well as by measuring real used lubricated oils. Sampling a large fluid volume with a decent 2D spatial resolution, this photonic micro sensor offers a powerful tool at very low cost and compacted size for in-line wear debris monitoring. PMID:28335436

  12. The Non-Destructive Test of Steel Corrosion in Reinforced Concrete Bridges Using a Micro-Magnetic Sensor

    PubMed Central

    Zhang, Hong; Liao, Leng; Zhao, Ruiqiang; Zhou, Jianting; Yang, Mao; Xia, Runchuan

    2016-01-01

    This paper presents a non-destructive test method for steel corrosion in reinforced concrete bridges by using a 3-dimensional digital micro-magnetic sensor to detect and analyze the self-magnetic field leakage from corroded reinforced concrete. The setup of the magnetic scanning device and the measurement mode of the micro-magnetic sensor are introduced. The numerical analysis model is also built based on the linear magnetic charge theory. Compared to the self-magnetic field leakage data obtained from magnetic sensor-based measurement and numerical calculation, it is shown that the curves of tangential magnetic field at different lift-off height all intersect near the edge of the steel corrosion zone. The result indicates that the intersection of magnetic field curves can be used to detect and evaluate the range of the inner steel corrosion in engineering structures. The findings of this work propose a new and effective non-destructive test method for steel corrosion, and therefore enlarge the application of the micro-magnetic sensor. PMID:27608029

  13. The Non-Destructive Test of Steel Corrosion in Reinforced Concrete Bridges Using a Micro-Magnetic Sensor.

    PubMed

    Zhang, Hong; Liao, Leng; Zhao, Ruiqiang; Zhou, Jianting; Yang, Mao; Xia, Runchuan

    2016-09-06

    This paper presents a non-destructive test method for steel corrosion in reinforced concrete bridges by using a 3-dimensional digital micro-magnetic sensor to detect and analyze the self-magnetic field leakage from corroded reinforced concrete. The setup of the magnetic scanning device and the measurement mode of the micro-magnetic sensor are introduced. The numerical analysis model is also built based on the linear magnetic charge theory. Compared to the self-magnetic field leakage data obtained from magnetic sensor-based measurement and numerical calculation, it is shown that the curves of tangential magnetic field at different lift-off height all intersect near the edge of the steel corrosion zone. The result indicates that the intersection of magnetic field curves can be used to detect and evaluate the range of the inner steel corrosion in engineering structures. The findings of this work propose a new and effective non-destructive test method for steel corrosion, and therefore enlarge the application of the micro-magnetic sensor.

  14. Structural control sensors for the CASES GTF

    NASA Technical Reports Server (NTRS)

    Davis, Hugh W.; Bukley, Angelia P.

    1993-01-01

    CASES (Controls, Astrophysics and Structures Experiment in Space) is a proposed space experiment to collect x-ray images of the galactic center and solar disk with unprecedented resolution. This requires precision pointing and suppression of vibrations in the long flexible structure that comprises the 32-m x-ray telescope optical bench. Two separate electro-optical sensor systems are provided for the ground test facility (GTF). The Boom Motion Tracker (BMT) measures eigenvector data for post-mission use in system identification. The Tip Displacement Sensor (TDS) measures boom tip position and is used as feedback for the closed-loop control system that stabilizes the boom. Both the BMT and the TDS have met acceptance specifications and were delivered to MSFC in February 1992. This paper describes the sensor concept, the sensor configuration as implemented in the GTF, and the results of characterization and performance testing.

  15. Structure and yarn sensor for fabric

    DOEpatents

    Mee, D.K.; Allgood, G.O.; Mooney, L.R.; Duncan, M.G.; Turner, J.C.; Treece, D.A.

    1998-10-20

    A structure and yarn sensor for fabric directly determines pick density in a fabric thereby allowing fabric length and velocity to be calculated from a count of the picks made by the sensor over known time intervals. The structure and yarn sensor is also capable of detecting full length woven defects and fabric. As a result, an inexpensive on-line pick (or course) density measurement can be performed which allows a loom or knitting machine to be adjusted by either manual or automatic means to maintain closer fiber density tolerances. Such a sensor apparatus dramatically reduces fabric production costs and significantly improves fabric consistency and quality for woven or knitted fabric. 13 figs.

  16. Porous Silicon Structures as Optical Gas Sensors

    PubMed Central

    Levitsky, Igor A.

    2015-01-01

    We present a short review of recent progress in the field of optical gas sensors based on porous silicon (PSi) and PSi composites, which are separate from PSi optochemical and biological sensors for a liquid medium. Different periodical and nonperiodical PSi photonic structures (bares, modified by functional groups or infiltrated with sensory polymers) are described for gas sensing with an emphasis on the device specificity, sensitivity and stability to the environment. Special attention is paid to multiparametric sensing and sensor array platforms as effective trends for the improvement of analyte classification and quantification. Mechanisms of gas physical and chemical sorption inside PSi mesopores and pores of PSi functional composites are discussed. PMID:26287199

  17. Micro-ring sensor used in the diagnosis of gastric cancer

    NASA Astrophysics Data System (ADS)

    Shi, Sichao; Cheng, Qing; Lin, Rong; Su, Da; Huang, Ying

    2016-01-01

    To find a detecting method that can be applied to the clinical screening and diagnosis, the cascaded micro-ring sensor with Vernier effect was used to distinguish gastric cancerous and normal cells. The simulation by FDTD of the cascaded microring sensor with different refractive indexes of the analyte (normal cells and gastric cancer cells) will be presented. In the simulation, with the refractive index's change Δn=0.02 for the two different analyte, the shift of sensor's resonant wavelength is 6.71nm. And the cascaded micro-ring sensor's sensitivity S is 335.5nm/RIU, and it is much larger compared to 19nm/RIU for a single ring sensor.

  18. Integrated micro-electro-mechanical sensor development for inertial applications

    SciTech Connect

    Allen, J.J.; Kinney, R.D.; Sarsfield, J.

    1998-04-01

    Electronic sensing circuitry and micro electro mechanical sense elements can be integrated to produce inertial instruments for applications unheard of a few years ago. This paper will describe the Sandia M3EMS fabrication process, inertial instruments that have been fabricated, and the results of initial characterization tests of micro-machined accelerometers.

  19. Magnetic bead counter using a micro-Hall sensor for biological applications

    SciTech Connect

    Lee, W.; Kim, K.; Joo, S.; Kim, S.U.; Rhie, K.; Hong, J.; Shin, K-H.; and Kim, K.H.

    2009-04-13

    Micro-Hall sensors have been fabricated, and various numbers of micron-size magnetic beads have been placed within the sensor area. The Hall resistances measured at room temperature are found to be proportional to the number of the beads, and are in good agreement with the numerically simulated results presented in this study. Our sensors are designed to measure the number of beads between zero and full-scale signals for a given number range of interest. The effects of miniaturizing the beads and sensors to nanoscale are also discussed.

  20. A Challenge for Micro and Mini UAV: The Sensor Problem

    DTIC Science & Technology

    2005-05-01

    pressure airspeed sensors on one single circuit board (Figure 8). Figure 8: Autopilot. The Quadcopter The fourth and final MAV is a quad-copter with...UNCLASSIFIED/UNLIMITED Figure 9: Quadcopter MAV. Figure 10: Loopshaping Diagram. The IMU contains 3 MEMS gyros. These form the rotational sensors Gx

  1. Micro optical fiber light source and sensor and method of fabrication thereof

    DOEpatents

    Kopelman, Raoul; Tan, Weihong; Shi, Zhong-You

    1994-01-01

    This invention relates generally to the development of and a method of fabricating a micro optical fiber light source. An optical fiber micro-light source is presented whose aperture is extremely small yet able to act as an intense light source. Light sources of this type have wide ranging applications, including use as micro-sensors in NSOM. Micro-sensor light sources have excellent detection limits as well as photo stability, reversibility, and millisecond response times. Furthermore, a method for manufacturing a micro optical fiber light source is provided. It involves the photo-chemical attachment of an optically active material onto the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture. More specifically, photopolymerization has been applied as a means to photo-chemically attach an optically active material. This process allows significant control of the size of the micro light source. Furthermore, photo-chemically attaching an optically active material enables the implementation of the micro-light source in a variety of sensor applications.

  2. Micro optical fiber light source and sensor and method of fabrication thereof

    DOEpatents

    Kopelman, R.; Tan, W.; Shi, Z.Y.

    1994-11-01

    This invention relates generally to the development of and a method of fabricating a micro optical fiber light source. An optical fiber micro-light source is presented whose aperture is extremely small yet able to act as an intense light source. Light sources of this type have wide ranging applications, including use as micro-sensors in NSOM. Micro-sensor light sources have excellent detection limits as well as photo stability, reversibility, and millisecond response times. Furthermore, a method for manufacturing a micro optical fiber light source is provided. It involves the photo-chemical attachment of an optically active material onto the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture. More specifically, photopolymerization has been applied as a means to photo-chemically attach an optically active material. This process allows significant control of the size of the micro light source. Furthermore, photo-chemically attaching an optically active material enables the implementation of the micro-light source in a variety of sensor applications. 4 figs.

  3. Analysis of a Micro-Optomechatronic Force Sensor

    NASA Astrophysics Data System (ADS)

    Fakhrabadi, M. M. S.; Ghanbari, A.; Rostami, A.; Janabi Sharifi, F.

    2010-11-01

    The purpose of this article is to study the dynamic behavior and modal analysis of a micro-optomechatronic device with primary applications to force sensing and optical attenuation/coupling. The system consists of two initially aligned micro-cantilevers with a narrow gap between them. The light beam enters to the first waveguide and, after propagation along it, couples to second waveguide through the mentioned narrow gap. The externally static or dynamic applied force on the first micro-cantilever deflects it and results in reduced optical coupling between the two waveguides. Changes in this factor are measured to give the properties of the applied force.

  4. Fully front-side bulk-micromachined single-chip micro flow sensors for bare-chip SMT (surface mounting technology) packaging

    NASA Astrophysics Data System (ADS)

    Liu, Jiedan; Wang, Jiachou; Li, Xinxin

    2012-03-01

    This paper reports novel single-wafer-based piezoresistive micro flow sensors, which are bulk micromachined only from the front side of the silicon wafer to facilitate the sensor-bare chips directly packaged into micro-fluidic systems with low-cost surface mounting technology (SMT). With neither double-sided micromachining nor multiwafer bonding needed, two structural types of the piezoresistive flow sensors are designed and fabricated in (1 1 1) wafers, where ‘type A’ sensor has a smaller channel cross section area compared to ‘type B’ sensor. After the bare sensor chip directly attached on a printed circuit board (PCB), wire bonded between the pads and the PCB for electric interconnection and the inlet/outlet front side connected, deionized water is flowed into the both types of flow sensors to characterize piezoresistive output of the differential pressure sensing elements in terms of the flow rate. For ‘type A’ and ‘type B’ sensors that are both power supplied with DC 5 V, the sensitivities are sequentially measured as 766.80 mV (µL s-1)-1 and 19.12 mV (µL s-1)-1, with the nonlinearities as 0.4% FS and 0.9% FS, respectively. Compared with traditionally fabricated micro flow sensors, the single-chip fabricated differential-pressure flow sensors can be low-cost volume manufactured. Moreover, the bare sensor chips can be simply SMT packaged for low-cost micro-system applications.

  5. The Combination of Micro Diaphragm Pumps and Flow Sensors for Single Stroke Based Liquid Flow Control.

    PubMed

    Jenke, Christoph; Pallejà Rubio, Jaume; Kibler, Sebastian; Häfner, Johannes; Richter, Martin; Kutter, Christoph

    2017-04-03

    With the combination of micropumps and flow sensors, highly accurate and secure closed-loop controlled micro dosing systems for liquids are possible. Implementing a single stroke based control mode with piezoelectrically driven micro diaphragm pumps can provide a solution for dosing of volumes down to nanoliters or variable average flow rates in the range of nL/min to μL/min. However, sensor technologies feature a yet undetermined accuracy for measuring highly pulsatile micropump flow. Two miniaturizable in-line sensor types providing electrical readout-differential pressure based flow sensors and thermal calorimetric flow sensors-are evaluated for their suitability of combining them with mircopumps. Single stroke based calibration of the sensors was carried out with a new method, comparing displacement volumes and sensor flow volumes. Limitations of accuracy and performance for single stroke based flow control are described. Results showed that besides particle robustness of sensors, controlling resistive and capacitive damping are key aspects for setting up reproducible and reliable liquid dosing systems. Depending on the required average flow or defined volume, dosing systems with an accuracy of better than 5% for the differential pressure based sensor and better than 6.5% for the thermal calorimeter were achieved.

  6. Solid state magnetic field sensors for micro unattended ground networks using spin dependent tunneling

    NASA Astrophysics Data System (ADS)

    Tondra, Mark; Nordman, Catherine A.; Lange, Erik H.; Reed, Daniel; Jander, Albrect; Akou, Seraphin; Daughton, James

    2001-09-01

    Micro Unattended Ground Sensor Networks will likely employ magnetic sensors, primarily for discrimination of objects as opposed to initial detection. These magnetic sensors, then, must fit within very small cost, size, and power budgets to be compatible with the envisioned sensor suites. Also, a high degree of sensitivity is required to minimize the number of sensor cells required to survey a given area in the field. Solid state magnetoresistive sensors, with their low cost, small size, and ease of integration, are excellent candidates for these applications assuming that their power and sensitivity performance are acceptable. SDT devices have been fabricated into prototype magnetic field sensors suitable for use in micro unattended ground sensor networks. They are housed in tiny SOIC 8-pin packages and mounted on a circuit board with required voltage regulation, signal amplification and conditioning, and sensor control and communications functions. The best sensitivity results to date are 289 pT/rt. Hz at 1 Hz, and and 7 pT/rt. Hz at f > 10 kHz. Expected near term improvements in performance would bring these levels to approximately 10 pT/rt Hz at 1 Hz and approximately 1 pT/rt. Hz at > 1 kHz.

  7. Micro manipulator motion control to counteract macro manipulator structural vibrations

    SciTech Connect

    Lew, J.Y.; Trudnowski, D.J.; Evans, M.S.; Bennett, D.W.

    1995-02-01

    Inertial force damping control by micro manipulator modulation is proposed to suppress the vibrations of a micro/macro manipulator system. The proposed controller, developed using classical control theory, is added to the existing control system. The proposed controller uses real-time measurements of macro manipulator flexibility to adjust the motion of the micro manipulator to counteract structural vibrations. Experimental studies using an existing micro/macro flexible link manipulator testbed demonstrate the effectiveness of the proposed approach to suppression of vibrations in the macro/micro manipulator system using micro-manipulator-based inertial active damping control.

  8. Magnetic Sensor for Building Structural Vibrations

    PubMed Central

    García, Alfonso; Morón, Carlos; Tremps, Enrique

    2014-01-01

    This paper shows a new displacement-to-frequency transducer based on the variation of a coil inductance when a magnetic core is partially or completely inserted inside. This transducer is based on a Colpitts oscillator due its low manufacturing price, behavior and immunity to noise. A tank circuit with a configuration in parallel was used because it can be employed at lower frequencies and it enables it to make a direct analysis. The sensor has a dynamic range equal to the length of the coil. The cores can exchange sensors (coils with its ferromagnetic core) using the same electronic measuring system. In this way, with only an electronic circuit, the core sensor determines the measurement range. The obtained resolution is higher than 1/100,000, and the sensor also allows the measurement and knowing in real time the effect of vibration, thermal expansion, referred overload movements, etc.., that can occur in the structural elements of a building. PMID:24504104

  9. Magnetic sensor for building structural vibrations.

    PubMed

    García, Alfonso; Morón, Carlos; Tremps, Enrique

    2014-02-05

    This paper shows a new displacement-to-frequency transducer based on the variation of a coil inductance when a magnetic core is partially or completely inserted inside. This transducer is based on a Colpitts oscillator due its low manufacturing price, behavior and immunity to noise. A tank circuit with a configuration in parallel was used because it can be employed at lower frequencies and it enables it to make a direct analysis. The sensor has a dynamic range equal to the length of the coil. The cores can exchange sensors (coils with its ferromagnetic core) using the same electronic measuring system. In this way, with only an electronic circuit, the core sensor determines the measurement range. The obtained resolution is higher than 1/100,000, and the sensor also allows the measurement and knowing in real time the effect of vibration, thermal expansion, referred overload movements, etc.., that can occur in the structural elements of a building.

  10. A micro resonant charge sensor with enhanced sensitivity based on differential sensing scheme and leverage mechanisms

    NASA Astrophysics Data System (ADS)

    Chen, Dongyang; Zhao, Jiuxuan; Xu, Zhonggui; Xie, Jin

    2016-10-01

    This letter reports a micro-electro-mechanical systems (MEMS) resonant charge sensor with enhanced sensitivity based on differential sensing scheme and leverage mechanisms. The sensor comprises two symmetrically-distributed double-ended tuning fork (DETF) resonators, each of which connects with dual micro-leverage mechanisms. The micro-leverages amplify electrostatic force in opposite directions and cause differential frequency shift of the two resonators. Both the resonators show a similar trend in behaviors of electrical and mechanical nonlinearity. Effect of environment disturbance is suppressed by the differential sensing scheme. The measured sensitivity of the two resonators are 3.31×10-4 Hz/fC2 and 1.85×10-4 Hz/fC2 respectively, and an overall sensitivity for the resonant charge sensor is 5.16×10-4 Hz/fC2.

  11. Sensor devices comprising field-structured composites

    DOEpatents

    Martin, James E.; Hughes, Robert C.; Anderson, Robert A.

    2001-02-27

    A new class of sensor devices comprising field-structured conducting composites comprising a textured distribution of conducting magnetic particles is disclosed. The conducting properties of such field-structured materials can be precisely controlled during fabrication so as to exhibit a large change in electrical conductivity when subject to any environmental influence which changes the relative volume fraction. Influences which can be so detected include stress, strain, shear, temperature change, humidity, magnetic field, electromagnetic radiation, and the presence or absence of certain chemicals. This behavior can be made the basis for a wide variety of sensor devices.

  12. Sensors, Volume 8, Micro- and Nanosensor Technology - Trends in Sensor Markets

    NASA Astrophysics Data System (ADS)

    Jones, Robert; Meixner, Hans

    1996-12-01

    Sensors is the first self-contained series to deal with the whole area of sensors. It describes general aspects, technical and physical fundamentals, construction, function, applications and developments of the various types of sensors. This final volume of the series uncovers trends in sensor technology and gives a comprehensive overview of the sensor market. The use of sensors in microsystems and in vacuum microelectronic as well as in acoustic wave devices is discussed. Present and emerging applications of sensors in aerospace, environmental, automotive, and medical industries, among others, are described. This volume is an indispensable reference work for both specialists and newcomers, researchers and developers

  13. Smart Sensors Assess Structural Health

    NASA Technical Reports Server (NTRS)

    2010-01-01

    NASA frequently inspects launch vehicles, fuel tanks, and other components for structural damage. To perform quick evaluation and monitoring, the Agency pursues the development of structural health monitoring systems. In 2001, Acellent Technologies Inc., of Sunnyvale, California, received Small Business Innovation Research (SBIR) funding from Marshall Space Flight Center to develop a hybrid Stanford Multi-Actuator Receiver Transduction (SMART) Layer for aerospace vehicles and structures. As a result, Acellent expanded the technology's capability and now sells it to aerospace and automotive companies; construction, energy, and utility companies; and the defense, space, transportation, and energy industries for structural condition monitoring, damage detection, crack growth monitoring, and other applications.

  14. Evaluation of High-Precision Sensors in Structural Monitoring

    PubMed Central

    Erol, Bihter

    2010-01-01

    One of the most intricate branches of metrology involves the monitoring of displacements and deformations of natural and anthropogenic structures under environmental forces, such as tidal or tectonic phenomena, or ground water level changes. Technological progress has changed the measurement process, and steadily increasing accuracy requirements have led to the continued development of new measuring instruments. The adoption of an appropriate measurement strategy, with proper instruments suited for the characteristics of the observed structure and its environmental conditions, is of high priority in the planning of deformation monitoring processes. This paper describes the use of precise digital inclination sensors in continuous monitoring of structural deformations. The topic is treated from two viewpoints: (i) evaluation of the performance of inclination sensors by comparing them to static and continuous GPS observations in deformation monitoring and (ii) providing a strategy for analyzing the structural deformations. The movements of two case study objects, a tall building and a geodetic monument in Istanbul, were separately monitored using dual-axes micro-radian precision inclination sensors (inclinometers) and GPS. The time series of continuous deformation observations were analyzed using the Least Squares Spectral Analysis Technique (LSSA). Overall, the inclinometers showed good performance for continuous monitoring of structural displacements, even at the sub-millimeter level. Static GPS observations remained insufficient for resolving the deformations to the sub-centimeter level due to the errors that affect GPS signals. With the accuracy advantage of inclination sensors, their use with GPS provides more detailed investigation of deformation phenomena. Using inclinometers and GPS is helpful to be able to identify the components of structural responses to the natural forces as static, quasi-static, or resonant. PMID:22163499

  15. Evaluation of high-precision sensors in structural monitoring.

    PubMed

    Erol, Bihter

    2010-01-01

    One of the most intricate branches of metrology involves the monitoring of displacements and deformations of natural and anthropogenic structures under environmental forces, such as tidal or tectonic phenomena, or ground water level changes. Technological progress has changed the measurement process, and steadily increasing accuracy requirements have led to the continued development of new measuring instruments. The adoption of an appropriate measurement strategy, with proper instruments suited for the characteristics of the observed structure and its environmental conditions, is of high priority in the planning of deformation monitoring processes. This paper describes the use of precise digital inclination sensors in continuous monitoring of structural deformations. The topic is treated from two viewpoints: (i) evaluation of the performance of inclination sensors by comparing them to static and continuous GPS observations in deformation monitoring and (ii) providing a strategy for analyzing the structural deformations. The movements of two case study objects, a tall building and a geodetic monument in Istanbul, were separately monitored using dual-axes micro-radian precision inclination sensors (inclinometers) and GPS. The time series of continuous deformation observations were analyzed using the Least Squares Spectral Analysis Technique (LSSA). Overall, the inclinometers showed good performance for continuous monitoring of structural displacements, even at the sub-millimeter level. Static GPS observations remained insufficient for resolving the deformations to the sub-centimeter level due to the errors that affect GPS signals. With the accuracy advantage of inclination sensors, their use with GPS provides more detailed investigation of deformation phenomena. Using inclinometers and GPS is helpful to be able to identify the components of structural responses to the natural forces as static, quasi-static, or resonant.

  16. Wavelength-independent integrated focus sensor using a reflection twin micro-Fresnel lens.

    PubMed

    Shiono, T; Setsune, K

    1989-12-01

    A compact focus sensor constructed with thin film components such as a reflection twin micro-Fresnel lens and a photodetector is proposed. This sensor has a folded optical path and is insensitive to wavelength shift. Theoretical analysis indicates that the optical performance of reflection Fresnel lenses can be improved in comparison with a conventional transmission micro-Fresnel lens. The reflection twin Fresnel lens was fabricated using electron-beam lithography and exhibited diffraction-limited focusing performance with high (71%) efficiency. It was demonstrated that the focus sensor had excellent spot displacement characteristics in agreement with theoretical results, and a focus error signal was detected. This focus sensor could be useful for the optical head of an optical disk system.

  17. The detection of specific biomolecular interactions with micro-Hall magnetic sensors.

    PubMed

    Manandhar, Pradeep; Chen, Kan-Sheng; Aledealat, Khaled; Mihajlović, Goran; Yun, C Steven; Field, Mark; Sullivan, Gerard J; Strouse, Geoffrey F; Chase, P Bryant; von Molnár, Stephan; Xiong, Peng

    2009-09-02

    The detection of reagent-free specific biomolecular interactions through sensing of nanoscopic magnetic labels provides one of the most promising routes to biosensing with solid-state devices. In particular, Hall sensors based on semiconductor heterostructures have shown exceptional magnetic moment sensitivity over a large dynamic field range suitable for magnetic biosensing using superparamagnetic labels. Here we demonstrate the capability of such micro-Hall sensors to detect specific molecular binding using biotin-streptavidin as a model system. We apply dip-pen nanolithography to selectively biotinylate the active areas of InAs micro-Hall devices with nanoscale precision. Specific binding of complementarily functionalized streptavidin-coated superparamagnetic beads to the Hall crosses occurs via molecular recognition, and magnetic detection of the assembled beads is achieved at room temperature using phase sensitive micro-Hall magnetometry. The experiment constitutes the first unambiguous demonstration of magnetic detection of specific biomolecular interactions with semiconductor micro-Hall sensors, and the selective molecular functionalization and resulting localized bead assembly demonstrate the possibility of multiplexed sensing of multiple target molecules using a single device with an array of micro-Hall sensors.

  18. Silicon cantilever sensor for micro-/nanoscale dimension and force metrology

    NASA Astrophysics Data System (ADS)

    Peiner, Erwin; Doering, Lutz; Balke, Michael; Christ, Andreas

    2007-05-01

    A piezoresistive silicon cantilever-type tactile sensor was described as well as its application for dimensional metrology with micro components and as a transferable force standard in the micro-to-nano Newton range. As an example for tactile probing metrology the novel cantilever sensor was used for surface scanning with calibrated groove and roughness artifacts. Force metrology was addressed based on calibration procedures which were developed for commercial stylus instruments as well as for glass pipettes designed for the characterization of the vital forces of isolated cells.

  19. Micro-optomechanical sensor for optical connection in the near field

    NASA Astrophysics Data System (ADS)

    Belier, B.; Santoso, A.; Bonnafe, J.; Nicu, L.; Temple-Boyer, P.; Bergaud, C.

    2000-09-01

    A micro-optomechanical sensor has been used to collect and carry optical information at the nanometer scale. This simple device consists of a SiNx microfabricated cantilever used simultaneously as an atomic-force microscope (AFM) probe and optical waveguide. When approaching the micro-optical cantilever close to the surface, the tip converts evanescent waves into radiative waves that propagate within the cantilever over long distances. Since the device is also employed as an AFM probe, mechanical contact is fully controlled as the tip approaches the surface, thus avoiding any crash. This sensor has been used to collect optical information from an optical fiber in the near field.

  20. A Fiber Bragg Grating Sensing-Based Micro-Vibration Sensor and Its Application

    PubMed Central

    Li, Tianliang; Tan, Yuegang; Zhou, Zude

    2016-01-01

    This paper proposes a fiber Bragg grating sensing-based micro-vibration sensor. The optical fiber has been directly treated as an elastomer to design the micro-vibration sensor, which possesses two FBGs. The mass is fixed on the middle of the fiber, and the vertical vibration of the mass has been converted into the axial tension/compression of the fiber. The principle of the sensor has been introduced, and the experiment conclusions show that the sensor sensitivity is 2362 pm/g within the range of 200–1200 mm/s2, which is consistent with theoretical analysis sensitivity of 2532.6 pm/g, and it shows an excellent linearity of 1.376%, while the resonant frequency of the sensor is 34 Hz, and the flat frequency range resides in the 0–22 Hz range. When used to measure micro-vibrations, its measured frequency relative error is less than 1.69% compared with the values acquired with a MEMS accelerometer, and the amplitude values of its measured vibration signal are consistent with the MEMS accelerometer under different excitation conditions too, so it can effectively realize the micro-vibration measurements. PMID:27092507

  1. A Fiber Bragg Grating Sensing-Based Micro-Vibration Sensor and Its Application.

    PubMed

    Li, Tianliang; Tan, Yuegang; Zhou, Zude

    2016-04-15

    This paper proposes a fiber Bragg grating sensing-based micro-vibration sensor. The optical fiber has been directly treated as an elastomer to design the micro-vibration sensor, which possesses two FBGs. The mass is fixed on the middle of the fiber, and the vertical vibration of the mass has been converted into the axial tension/compression of the fiber. The principle of the sensor has been introduced, and the experiment conclusions show that the sensor sensitivity is 2362 pm/g within the range of 200-1200 mm/s², which is consistent with theoretical analysis sensitivity of 2532.6 pm/g, and it shows an excellent linearity of 1.376%, while the resonant frequency of the sensor is 34 Hz, and the flat frequency range resides in the 0-22 Hz range. When used to measure micro-vibrations, its measured frequency relative error is less than 1.69% compared with the values acquired with a MEMS accelerometer, and the amplitude values of its measured vibration signal are consistent with the MEMS accelerometer under different excitation conditions too, so it can effectively realize the micro-vibration measurements.

  2. Concept Studies of Micro-Pump for Chemical Concentration in Handheld Micro Sensors

    DTIC Science & Technology

    2007-11-02

    This report summarizes the preliminary results of a short-term innovative research project on the concept study of micro pumps for chemical...main objective of the work is to study the feasibility of certain micro pumping concepts and their potential integration with the sensing material and... micro pumps is demonstrated, although the quantitative assessment of the pumping system is still elusive, partly because of lack of specifications. The

  3. Development of a micro-potentiometric sensor for the microchip analysis of alkali ions.

    PubMed

    Smirnova, Adelina; Mawatari, Kazuma; Takahashi, Hiroko; Tanaka, Yo; Nakanishi, Hiroaki; Kitamori, Takehiko

    2009-12-01

    This paper reports on the development of a micro-potentiometric sensor based on external microelectrodes introduced into a microchip. We miniaturized reference and ion-selective electrodes (ISEs) and embedded them into a plastic (PDMS) microchip; the miniaturization of ISE was attained by using a monolithic capillary-based membrane. This sensor was applied to the detection of alkali ions (Na+, K+ and NH4+) in a microflow on the microg/L level.

  4. Design of acoustic wave biochemical sensors using micro-electro-mechanical systems

    NASA Astrophysics Data System (ADS)

    Valentine, Jane E.; Przybycien, Todd M.; Hauan, Steinar

    2007-03-01

    Acoustic wave biochemical sensors work by detecting the frequency shifts resulting from the binding of target molecules to a functionalized resonator. Resonator types currently in use or under development include macroscopic quartz crystal microbalances (QCMs) as well as a number of different integrated Micro-electro-mechanical Systems (MEMS) structures. Due to an increased resonator surface area to mass ratio, we believe that membrane-based MEMS systems are particularly promising with regard to sensitivity. Prototypes have been developed [S. Hauan et al., U.S. Patent Application (filed 6 Nov. 2003)] and preliminary calculations [M. J. Bartkovsky et al., paper 385e presented at the AIChE Annual Meeting, Nov. 2003; J. E. Valentine et al., paper 197h presented at the AICHE Annual Meeting, Nov. 2003] indicate significant improvements over other methods, both macroscopic and MEMS based. In this article we describe our work on a MEMS-based acoustic wave biochemical sensor using a membrane resonator. We demonstrate the effects of spatial distributions of mass on the membrane on sensitivity and show how to use this spatial sensitivity to detect multiple targets simultaneously. To do so we derive a function approximating the membrane response surface to spatial mass loadings under the applicable range of conditions. We verify the agreement using finite element methods, and present our initial sensitivity calculations demonstrating the advantages of variable mass loadings.

  5. Validation of a new micro-manometer pressure sensor for cardiovascular measurements in mice.

    PubMed

    Trevino, Rodolfo J; Jones, Douglas L; Escobedo, Daniel; Porterfield, John; Larson, Erik; Chisholm, Gary B; Barton, Amanda; Feldman, Marc D

    2010-01-01

    Abstract The Scisense (London, ON, Canada) micro-manometer pressure sensor is currently being used by investigators to evaluate cardiovascular physiology in mice, but has not been validated to date. The purpose of the current study is to compare the 1.2 F Scisense pressure sensor to the current gold standard produced by Millar Instruments (Houston, TX) (1.4 F). In vitro comparisons were preformed including temperature drift, frequency response analysis up to 250 Hz, and damping coefficient and natural frequency determined via a pop test. The authors also performed in vivo comparisons including pressure drift, dose-response studies to IV isoproterenol, maximum adrenergic stimulation with IV dobutamine, and simultaneous placement of both micro-manometer pressure sensors in the same intact murine hearts. The authors conclude that both sensors are equivalent, and that the Scisense pressure sensor represents an alternative to the current gold standard, the Millar micro-manometer pressure sensor for in vivo pressure measurements in the mouse.

  6. A micro-Doppler sonar for acoustic surveillance in sensor networks

    NASA Astrophysics Data System (ADS)

    Zhang, Zhaonian

    Wireless sensor networks have been employed in a wide variety of applications, despite the limited energy and communication resources at each sensor node. Low power custom VLSI chips implementing passive acoustic sensing algorithms have been successfully integrated into an acoustic surveillance unit and demonstrated for detection and location of sound sources. In this dissertation, I explore active and passive acoustic sensing techniques, signal processing and classification algorithms for detection and classification in a multinodal sensor network environment. I will present the design and characterization of a continuous-wave micro-Doppler sonar to image objects with articulated moving components. As an example application for this system, we use it to image gaits of humans and four-legged animals. I will present the micro-Doppler gait signatures of a walking person, a dog and a horse. I will discuss the resolution and range of this micro-Doppler sonar and use experimental results to support the theoretical analyses. In order to reduce the data rate and make the system amenable to wireless sensor networks, I will present a second micro-Doppler sonar that uses bandpass sampling for data acquisition. Speech recognition algorithms are explored for biometric identifications from one's gait, and I will present and compare the classification performance of the two systems. The acoustic micro-Doppler sonar design and biometric identification results are the first in the field as the previous work used either video camera or microwave technology. I will also review bearing estimation algorithms and present results of applying these algorithms for bearing estimation and tracking of moving vehicles. Another major source of the power consumption at each sensor node is the wireless interface. To address the need of low power communications in a wireless sensor network, I will also discuss the design and implementation of ultra wideband transmitters in a three dimensional

  7. Selective binding and detection of magnetic labels using PHR sensor via photoresist micro-wells.

    PubMed

    Oh, Sunjong; Baek, Nam Seob; Jung, Sang-Don; Chung, Myung-Ae; Hung, Tran Quang; Anandakumar, S; Rani, V Sudha; Jeong, Jong-Ryul; Kim, CheolGi

    2011-05-01

    We have developed a novel platform for selective binding of magnetic labels on planar Hall resistance sensor (PHR) for biosensing applications. The photoresist (PR) micro wells were prepared on the PHR sensor junctions to trap the magnetic bead at specified locations on the sensor surface and thin layer of Au was sputtered in the PR wells immobilize bimolecular. The Au surface is functionalized with single-stranded oligonucleotide and further biotin was used to immobilize streptavidin coated magnetic labels (Dynabeads Myone 1.0 microm, Invitrogen Co.). After removal of the PR wells on the sensor surface the non specific binding magnetic labels were successfully removed and only the chemically bounded magnetic labels were remained on the Au surface for detection of biomolecules using PHR sensor. We controlled the number of magnetic labels on the PHR sensor surface by using different sizes of the PR well on the junctions. The specifically bounded magnetic labels were successfully detected by characterizing the individual PHR sensor junctions. This technique enables the complete control over the magnetic labels for selective binding of biomolecules on the sensor surface for increasing the sensitivity of the PHR sensor as well as removal of the non specific bindings on the sensor surface.

  8. GRIN-optics-based hyperspectral imaging micro-sensor

    NASA Astrophysics Data System (ADS)

    Zhou, Wei; Leger, James

    2007-09-01

    By utilizing diffractive, refractive and graded-index optics technology, a miniature (1 mm x 1 mm x 2 mm) Computer-Tomography Imaging Spectrometer (CTIS) sensor has been designed with 16 independent optical channels working in a snap-shot mode for hyper-spectral imaging. The designed prototype covers a 400~700 nm wavelength range. One optical channel has been fabricated and characterized. By azimuthally rotating this optical channel along the optical axis and collecting different dispersed images to simulate the full sensor read-out, the full hyperspectral detection scheme has been demonstrated.

  9. Combined simulation of a micro permanent magnetic linear contactless displacement sensor.

    PubMed

    Gao, Jing; Müller, Wolfgang F O; Greiner, Felix; Eicher, Dirk; Weiland, Thomas; Schlaak, Helmut F

    2010-01-01

    The permanent magnetic linear contactless displacement (PLCD) sensor is a new type of displacement sensor operating on the magnetic inductive principle. It has many excellent properties and has already been used for many applications. In this article a Micro-PLCD sensor which can be used for microelectromechanical system (MEMS) measurements is designed and simulated with the CST EM STUDIO(®) software, including building a virtual model, magnetostatic calculations, low frequency calculations, steady current calculations and thermal calculations. The influence of some important parameters such as air gap dimension, working frequency, coil current and eddy currents etc. is studied in depth.

  10. A micro flow sensor from a polymer for gases and liquids

    NASA Astrophysics Data System (ADS)

    Ahrens, R.; Schlote-Holubek, K.

    2009-07-01

    In this paper, we present a micro flow sensor from a polymer based on the thermal anemometric principle. A sensor with outer dimensions of 5.5 × 6 × 1.2 mm3 and a small fluidic channel with a cross-section of 240 µm × 400 µm may be operated with both gases (up to 200 ml min-1) and liquids (for water up to 200 µl min-1). Due to its small heat capacity, the sensor is also suitable for dynamical measurements of liquid flows, e.g. flow pulsations up to several 100 Hz even within high-pressure hydraulic systems.

  11. Strain evaluation of strengthened concrete structures using FBG sensors

    NASA Astrophysics Data System (ADS)

    Lau, Kin-tak; Zhou, Li-min; Ye, Lin

    1999-12-01

    Fibre-optic Bragg Grating (FBG) sensor presents a great deal of potential in monitoring the internal status of the concrete structures after repairing or strengthening by an external adhered reinforcement. It can be used in a variety of configurations ranging from pointwise to multi-point strain measurement in order to investigate the strain distribution of the structures. In this paper, an experimental investigation on the rectangular notched-concrete beam, which was strengthened by glass fibre composites with the embedment of multiplexing FBG sensors is presented. Three point bending test was performed to investigate the strain profile of the specimen. Frequency modulated continuous wave (FMCW) technique was used to measure the strain variation of the fibre-grating regions. The results give a good agreement with the electrical resistance strain gauge in early loading condition. The difference of the strain-measuring results between the strain-gauge and FBG sensor was increased when further increasing the applied load. It was suspected that the micro/marco cracks occurred on the concrete surface and that the externally bonded strain-measuring device cannot be detected.

  12. Strain evaluation of strengthened concrete structures using FBG sensors

    SciTech Connect

    Lau Kintak; Zhou Limin; Ye Lin

    1999-12-02

    Fibre-optic Bragg Grating (FBG) sensor presents a great deal of potential in monitoring the internal status of the concrete structures after repairing or strengthening by an external adhered reinforcement. It can be used in a variety of configurations ranging from pointwise to multi-point strain measurement in order to investigate the strain distribution of the structures. In this paper, an experimental investigation on the rectangular notched-concrete beam, which was strengthened by glass fibre composites with the embedment of multiplexing FBG sensors is presented. Three point bending test was performed to investigate the strain profile of the specimen. Frequency modulated continuous wave (FMCW) technique was used to measure the strain variation of the fibre-grating regions. The results give a good agreement with the electrical resistance strain gauge in early loading condition. The difference of the strain-measuring results between the strain-gauge and FBG sensor was increased when further increasing the applied load. It was suspected that the micro/marco cracks occurred on the concrete surface and that the externally bonded strain-measuring device cannot be detected.

  13. Injection moulding of optical functional micro structures using laser structured, PVD-coated mould inserts

    NASA Astrophysics Data System (ADS)

    Hopmann, Ch.; Weber, M.; Schöngart, M.; Schäfer, C.; Bobzin, K.; Bagcivan, N.; Brögelmann, T.; Theiß, S.; Münstermann, T.; Steger, M.

    2015-05-01

    Micro structured optical plastics components are intensively used i. e. in consumer electronics, for optical sensors in metrology, innovative LED-lighting or laser technology. Injection moulding has proven to be successful for the large-scale production of those parts. However, the production of those parts still causes difficulties due to challenges in the moulding and demoulding of plastics parts created with laser structured mould inserts. A complete moulding of the structures often leads to increased demoulding forces, which then cause a breaking of the structures and a clogging of the mould. An innovative approach is to combine PVD-coated (physical vapour deposition), laser structured inserts and a variothermal moulding process to create functional mic8iüro structures in a one-step process. Therefore, a PVD-coating is applied after the laser structuring process in order to improve the wear resistance and the anti-adhesive properties against the plastics melt. In a series of moulding trials with polycarbonate (PC) and polymethylmethacrylate (PMMA) using different coated moulds, the mould temperature during injection was varied in the range of the glass transition and the melt temperature of the polymers. Subsequently, the surface topography of the moulded parts is evaluated by digital 3D laser-scanning microscopy. The influence of the moulding parameters and the coating of the mould insert on the moulding accuracy and the demoulding behaviour are being analysed. It is shown that micro structures created by ultra-short pulse laser ablation can be successfully replicated in a variothermal moulding process. Due to the mould coating, significant improvements could be achieved in producing micro structured optical plastics components.

  14. Injection moulding of optical functional micro structures using laser structured, PVD-coated mould inserts

    SciTech Connect

    Hopmann, Ch.; Weber, M.; Schöngart, M.; Schäfer, C.; Bobzin, K.; Bagcivan, N.; Brögelmann, T.; Theiß, S.; Münstermann, T.; Steger, M.

    2015-05-22

    Micro structured optical plastics components are intensively used i. e. in consumer electronics, for optical sensors in metrology, innovative LED-lighting or laser technology. Injection moulding has proven to be successful for the large-scale production of those parts. However, the production of those parts still causes difficulties due to challenges in the moulding and demoulding of plastics parts created with laser structured mould inserts. A complete moulding of the structures often leads to increased demoulding forces, which then cause a breaking of the structures and a clogging of the mould. An innovative approach is to combine PVD-coated (physical vapour deposition), laser structured inserts and a variothermal moulding process to create functional mic8iüro structures in a one-step process. Therefore, a PVD-coating is applied after the laser structuring process in order to improve the wear resistance and the anti-adhesive properties against the plastics melt. In a series of moulding trials with polycarbonate (PC) and polymethylmethacrylate (PMMA) using different coated moulds, the mould temperature during injection was varied in the range of the glass transition and the melt temperature of the polymers. Subsequently, the surface topography of the moulded parts is evaluated by digital 3D laser-scanning microscopy. The influence of the moulding parameters and the coating of the mould insert on the moulding accuracy and the demoulding behaviour are being analysed. It is shown that micro structures created by ultra-short pulse laser ablation can be successfully replicated in a variothermal moulding process. Due to the mould coating, significant improvements could be achieved in producing micro structured optical plastics components.

  15. Microscope-on-Chip Using Micro-Channel and Solid State Image Sensors

    NASA Technical Reports Server (NTRS)

    Wang, Yu

    2000-01-01

    Recently, Jet Propulsion Laboratory has invented and developed a miniature optical microscope, microscope-on-chip using micro-channel and solid state image sensors. It is lightweight, low-power, fast speed instrument, it has no image lens, does not need focus adjustment, and the total mass is less than 100g. A prototype has been built and demonstrated at JPL.

  16. A micro-thermoelectric gas sensor for detection of hydrogen and atomic oxygen.

    PubMed

    Park, Se-Chul; Yoon, Seung-Il; Lee, Chung-il; Kim, Yong-Jun; Song, Soonho

    2009-02-01

    This paper demonstrates the fabrication and performance of a micro-thermoelectric gas sensor for an effective and inexpensive gas analysis system. The proposed micro-thermoelectric gas sensor was fabricated by using a surface micromachining technique. The sensing mechanism, consisting of thermoelectric material and a novel metal catalyst, was fabricated on the highly thermally resistive layer for reduced heat transfer to the substrate allowing for a simple fabrication process. The micro-thermoelectric gas sensor detects target gas species by measuring the reaction heat of the catalytic reaction between the target gas and a novel metal catalyst using Cu-Bi thermopiles. The catalytic reaction occurs only on the hot junction of the sensing thermopile where the metal catalyst is deposited. In order to reduce the external thermal noise, a difference between the output voltage of the sensing and the reference thermopiles was measured by using a differential amplifier. The response of the fabricated sensor was linear to temperature difference. The fabricated sensor can be used to detect various concentrations of hydrogen and atomic oxygen, where the output voltage linearly increased with the gas concentration.

  17. In situ monitoring of temperature inside lithium-ion batteries by flexible micro temperature sensors.

    PubMed

    Lee, Chi-Yuan; Lee, Shuo-Jen; Tang, Ming-Shao; Chen, Pei-Chi

    2011-01-01

    Lithium-ion secondary batteries are commonly used in electric vehicles, smart phones, personal digital assistants (PDA), notebooks and electric cars. These lithium-ion secondary batteries must charge and discharge rapidly, causing the interior temperature to rise quickly, raising a safety issue. Over-charging results in an unstable voltage and current, causing potential safety problems, such as thermal runaways and explosions. Thus, a micro flexible temperature sensor for the in in-situ monitoring of temperature inside a lithium-ion secondary battery must be developed. In this work, flexible micro temperature sensors were integrated into a lithium-ion secondary battery using the micro-electro-mechanical systems (MEMS) process for monitoring temperature in situ.

  18. Numerical Study on the Particle Trajectory Tracking in a Micro-UV Bio-Fluorescence Sensor.

    PubMed

    Byeon, Sun-Seok; Cho, Moon-Young; Lee, Jong-Chul; Kim, Youn-Jea

    2015-03-01

    A micro-UV bio-fluorescence sensor was developed to detect primary biological aerosols including bacteria, bacterial spores, fungal spores, pollens, viruses, algae, etc. In order to effectively detect the bio-particles in a micro-UV bio-fluorescence sensor, numerical calculations were performed to adjust for appropriate flow conditions of the sensor by regulating the sample aerosols and sheath flow. In particular, a CFD-based model of hydrodynamic processes was developed by computing the trajectory of particles using commercially available ANSYS CFX-14 software and the Lagrangian tracking model. The established model was evaluated with regard to the variation of sheath flow rate and particle size. Results showed that the sheath flow was changed rapidly at the end of nozzle tip, but the sample particles moved near the center of aerosol jet for aerodynamic focusing with little deviation from the axis.

  19. Fabrication and Characteristics of Micro-Electro-Mechanical-System-Based Tilt Sensor

    NASA Astrophysics Data System (ADS)

    Choi, Ju Chan; Kong, Seong Ho

    2009-06-01

    A miniaturized tilt sensor using air medium, which is measurable on a two-axis inclination angle, is fabricated and its output characteristics are evaluated. The proposed tilt sensor consists of a central microheater surrounded by four temperature sensors. Without an inclination, the microheater creates a symmetric temperature profile in an encapsulated microchamber filled with air medium. When the device is tilted, the temperature sensors formed around the central heater measure the asymmetric temperature profile, caused by the effect of convection. The proposed tilt sensor covers a measurement range of ±90° on two axes with excellent linearity and symmetric sensitivity. Furthermore, the structure and fabrication sequence of the proposed sensor are quite simple; that is, the microheater and temperature sensors can be simultaneously formed because they are made of the same material. Several issues, confronting the previously reported electrolytic tilt sensor, such as metal electrode corrosion, electrolyte deterioration, surface tension of the electrolyte, and difficulty in packaging, were avoided.

  20. Development of Micro Air Reconnaissance Vehicle as a Test Bed for Advanced Sensors and Electronics

    NASA Technical Reports Server (NTRS)

    Shams, Qamar A.; Vranas, Thomas L.; Fox, Robert L.; Kuhn, Theodore R.; Ingham, John; Logan, Michael J.; Barnes, Kevin N.; Guenther, Benjamin F.

    2002-01-01

    This paper describes the development of a Micro/Mini Air Reconnaissance Vehicle for advanced sensors and electronics at NASA Langley Research Center over the last year. This vehicle is expected to have a total weight of less than four pounds, a design velocity of 40 mph, an endurance of 15-20 minutes, and a maximum range of 5km. The vehicle has wings that are simple to detach yet retain the correct alignment. The upper fuselage surface has a quick release hatch used to access the interior and also to mount the varying propulsion systems. The sensor suite developed for this vehicle consists of a Pitot-static measurement system for determining air speed, an absolute pressure measurement for determining altitude, magnetic direction measurement, and three orthogonal gyros to determine body angular rates. Swarming GPS-guidance and in-flight maneuvering is discussed, as well as design and installation of some other advance sensors like MEMS microphones, infrared cameras, GPS, humidity sensors, and an ultrasonic sonar sensor. Also low cost, small size, high performance control and navigation system for the Micro Air Vehicle is discussed. At the end, laboratory characterization of different sensors, motors, propellers, and batteries will be discussed.

  1. Fabrication of micro-rotating structure by micro reciprocated wire-EDM

    NASA Astrophysics Data System (ADS)

    Wang, Yukui; Chen, Xiang; Wang, Zhenlong; Li, Huichao; Liu, Hongzheng

    2016-11-01

    Micro rotating-structure manufacture has been largely carried out using a variety of processing methods. However, it is difficult to achieve the high-precise machining of the micro rotating structure due to the material constraints and the geometrical limitation of the free-form profile. This paper discusses the fabrication of micro-rotating structure using micro reciprocated wire electrical discharge machining (wire-EDM). To ensure machining accuracy, a gravity takeup for maintaining constant wire tension and a unit for suppressing the wire vibration are designed and fabricated, respectively. Besides, the effects of processing parameters on rotating groove width are investigated by conducting preliminary experiments, showing that high open voltage, discharge capacitance and revolving speed, and low discharge resistance and wire tension cause larger rotating groove width. Nevertheless, the rotating groove width firstly decreases with the reference voltage and feed rate increase in the initial stage and then increases when applying higher values. Based on the preliminary experiments, the proper processing parameters are determined and are used for machining micro bellows core-mould. Ultimately, the micro bellows core-mould is successfully machined by micro reciprocated wire-EDM, exhibiting high machining accuracy, excellent geometric shape and uniformity. Specifically, the machining errors along the axial direction and the radial direction of the micro bellows core-mould are less than 1.4 µm and 2.3 µm, respectively.

  2. Design and experiment of spectrometer based on scanning micro-grating integrating with angle sensor

    NASA Astrophysics Data System (ADS)

    Biao, Luo; Wen, Zhi-yu

    2014-01-01

    A compact, low cost, high speed, non-destructive testing NIR (near infrared) spectrometer optical system based on MOEMS grating device is developed. The MOEMS grating works as the prismatic element and wavelength scanning element in our optical system. The MOEMS grating enables the design of compact grating spectrometers capable of acquiring full spectra using a single detector element. This MOEMS grating is driven by electromagnetic force and integrated with angle sensor which used to monitored deflection angle while the grating working. Comparing with the traditional spectral system, there is a new structure with a single detector and worked at high frequency. With the characteristics of MOEMS grating, the structure of the spectrometer system is proposed. After calculating the parameters of the optical path, ZEMAX optical software is used to simulate the system. According the ZEMAX output file of the 3D model, the prototype is designed by SolidWorks rapidly, fabricated. Designed for a wavelength range between 800 nm and 1500 nm, the spectrometer optical system features a spectral resolution of 16 nm with the volume of 97 mm × 81.7 mm × 81 mm. For the purpose of reduce modulated effect of sinusoidal rotation, spectral intensity of the different wavelength should be compensated by software method in the further. The system satisfies the demand of NIR micro-spectrometer with a single detector.

  3. Fully Self-Contained Vision-Aided Navigation and Landing of a Micro Air Vehicle Independent from External Sensor Inputs

    NASA Technical Reports Server (NTRS)

    Brockers, Roland; Susca, Sara; Zhu, David; Matthies, Larry

    2012-01-01

    Direct-lift micro air vehicles have important applications in reconnaissance. In order to conduct persistent surveillance in urban environments, it is essential that these systems can perform autonomous landing maneuvers on elevated surfaces that provide high vantage points without the help of any external sensor and with a fully contained on-board software solution. In this paper, we present a micro air vehicle that uses vision feedback from a single down looking camera to navigate autonomously and detect an elevated landing platform as a surrogate for a roof top. Our method requires no special preparation (labels or markers) of the landing location. Rather, leveraging the planar character of urban structure, the landing platform detection system uses a planar homography decomposition to detect landing targets and produce approach waypoints for autonomous landing. The vehicle control algorithm uses a Kalman filter based approach for pose estimation to fuse visual SLAM (PTAM) position estimates with IMU data to correct for high latency SLAM inputs and to increase the position estimate update rate in order to improve control stability. Scale recovery is achieved using inputs from a sonar altimeter. In experimental runs, we demonstrate a real-time implementation running on-board a micro aerial vehicle that is fully self-contained and independent from any external sensor information. With this method, the vehicle is able to search autonomously for a landing location and perform precision landing maneuvers on the detected targets.

  4. Study of poly (3-hexylthiophene) conducting polymer thin film micro-sensor for hydrazine vapor detection

    NASA Astrophysics Data System (ADS)

    Yang, Hong

    This dissertation discussed the construction and investigation of a poly (3-hexylthiophene) conducting polymer based thin film micro-sensor for a real-time detection of hydrazine vapor at ambient pressure. A type of low cost, small size, passive poly (3-hexylthiophene) thin film micro-sensor was designed and fabricated. The micro-sensor platform consisted of a rectangular shaped inert substrate and gold interdigited electrode pairs. A layer of poly (3-hexylthiophene) thin film was coated onto the sensor platform using a spin coating method, and nitrosonium hexafluorophosphate (NOPF6) was used to dope the poly (3-hexylthiophene) thin film to increase its electrical conductivity and form the finished sensor. The basic responses of the sensor to hydrazine vapor were experimentally investigated. The primary results showed that the sensor responded to hydrazine vapor in less than a few seconds; attained orders of magnitude change in normalized resistance during hydrazine exposure, and was not easily saturated. The interaction between the hydrazine gas molecules and doped poly (3-hexylthiophene) thin film was studied. The plausible mechanism was determined as: Charge carriers inside the doped poly (3-hexylthiophene) thin film were depleted during the oxidation-reduction chemical reaction between the hydrazine vapor and polymer film, resulting a reduction in the polymer film's electrical conductivity. Experiments were also conducted to find out the effects of hydrazine concentration, poly (3-hexylthiophene) thin film thickness, sensor storage time, environment temperature, and environment humidity on the sensor's performance. The response rate of the sensor under different sensing conditions was calculated and discussed. A diffusion-reaction model was applied to simulate the interaction between hydrazine molecules and doped poly (3-hexylthiophene) thin film. The profiles of hydrazine gas diffusion and positive charge carrier neutralization in the polymer film were

  5. Identification of Cross-Country Skiing Movement Patterns Using Micro-Sensors

    PubMed Central

    Marsland, Finn; Lyons, Keith; Anson, Judith; Waddington, Gordon; Macintosh, Colin; Chapman, Dale

    2012-01-01

    This study investigated the potential of micro-sensors for use in the identification of the main movement patterns used in cross-country skiing. Data were collected from four elite international and four Australian athletes in Europe and in Australia using a MinimaxX™ unit containing accelerometer, gyroscope and GPS sensors. Athletes performed four skating techniques and three classical techniques on snow at moderate velocity. Data from a single micro-sensor unit positioned in the centre of the upper back was sufficient to visually identify cyclical movement patterns for each technique. The general patterns for each technique were identified clearly across all athletes while at the same time distinctive characteristics for individual athletes were observed. Differences in speed, snow condition and gradient of terrain were not controlled in this study and these factors could have an effect on the data patterns. Development of algorithms to process the micro-sensor data into kinematic measurements would provide coaches and scientists with a valuable performance analysis tool. Further research is needed to develop such algorithms and to determine whether the patterns are consistent across a range of different speeds, snow conditions and terrain, and for skiers of differing ability. PMID:22666075

  6. Developments and Applications of Electrogenerated Chemiluminescence Sensors Based on Micro- and Nanomaterials

    PubMed Central

    Hazelton, Sandra G.; Zheng, Xingwang; Zhao, Julia Xiaojun; Pierce, David T.

    2008-01-01

    A variety of recent developments and applications of electrogenerated chemiluminescence (ECL) for sensors are described. While tris(2,2′-bipyridyl)-ruthenium(II) and luminol have dominated and continue to pervade the field of ECL-based sensors, recent work has focused on use of these lumophores with micro- and nanomaterials. It has also extended to inherently luminescent nanomaterials, such as quantum dots. Sensor configurations including microelectrode arrays and microfluidics are reviewed and, with the recent trend toward increased use of nanomaterials, special attention has been given to sensors which include thin films, nanoparticles and nanotubes. Applications of ECL labels and examples of label-free sensing that incorporate nanomaterials are also discussed. PMID:27873850

  7. Efficient gas sensitivity in mixed bismuth ferrite micro (cubes) and nano (plates) structures

    SciTech Connect

    Waghmare, Shivaji D.; Jadhav, Vijaykumar V.; Gore, Shaym K.; Yoon, Seog-Joon; Ambade, Swapnil B.; Lokhande, B.J.; Mane, Rajaram S.; Han, Sung-Hwan

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Micro (cubes) structure embedded in nano (plates) of bismuth ferrite was prepared by a chemical method. ► These structures were characterized by XRD and SEM. ► LPG, CO{sub 2} and NH{sub 4} gases were exposed. ► Properties related to gas sensors were measured and reported. -- Abstract: Mixed micro (cubes) and nano (plates) structures of bismuth ferrite (BFO) have been synthesized by a simple and cost-effective wet-chemical method. Structural, morphological and phase confirmation characteristics are measured using X-ray diffraction, field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis techniques. The digital FE-SEM photo-images of BFO sample confirmed an incubation of discrete micro-cubes into thin and regularly placed large number of nano-plates. The bismuth ferrite, with mixed structures, films show considerable performance when used in liquefied petroleum (LPG), carbon dioxide (CO{sub 2}) and ammonium (NH{sub 3}) gas sensors application. Different chemical entities in LPG have made it more efficient with higher sensitivity, recovery and response times compared to CO{sub 2} and NH{sub 3} gases. Furthermore, effect of palladium surface treatment on the gas sensitivity and the charge transfer resistances of BFO mixed structures is investigated and reported.

  8. Application of an evolutionary algorithm in the optimal design of micro-sensor.

    PubMed

    Lu, Qibing; Wang, Pan; Guo, Sihai; Sheng, Buyun; Liu, Xingxing; Fan, Zhun

    2015-01-01

    This paper introduces an automatic bond graph design method based on genetic programming for the evolutionary design of micro-resonator. First, the system-level behavioral model is discussed, which based on genetic programming and bond graph. Then, the geometry parameters of components are automatically optimized, by using the genetic algorithm with constraints. To illustrate this approach, a typical device micro-resonator is designed as an example in biomedicine. This paper provides a new idea for the automatic optimization design of biomedical sensors by evolutionary calculation.

  9. Numerical investigations on the wake structures of micro-ramp and micro-vanes

    NASA Astrophysics Data System (ADS)

    DaWen, Xue; ZhiHua, Chen; XiaoHai, Jiang; BaoChun, Fan

    2014-02-01

    Based on large eddy simulation, combined with the high-order WENO (weighted essentially non-oscillatory schemes) scheme, immersed boundary method and adaptive mesh refinement technique, the supersonic flow past a wall-mounted micro-ramp and two micro-vanes have been simulated. The different wake structures are presented and discussed. Our numerical results showed that wake structures behind the micro-ramp are more complicated, including ring-like vortex train, and streamwise vortex tubes etc. However, the wake structures of the micro-vanes are quite simple; they are mainly the two counter-rotating streamwise vortex tubes. The control of boundary flow of both is achieved through the energy exchange between the main stream and the boundary layer and is presented mainly by the upwash and downwash motion of gases under the entrainment of vortex tubes.

  10. Modeling, design, fabrication and characterization of a micro Coriolis mass flow sensor

    NASA Astrophysics Data System (ADS)

    Haneveld, J.; Lammerink, T. S. J.; de Boer, M. J.; Sanders, R. G. P.; Mehendale, A.; Lötters, J. C.; Dijkstra, M.; Wiegerink, R. J.

    2010-12-01

    This paper discusses the modeling, design and realization of micromachined Coriolis mass flow sensors. A lumped element model is used to analyze and predict the sensor performance. The model is used to design a sensor for a flow range of 0-1.2 g h-1 with a maximum pressure drop of 1 bar. The sensor was realized using semi-circular channels just beneath the surface of a silicon wafer. The channels have thin silicon nitride walls to minimize the channel mass with respect to the mass of the moving fluid. Special comb-shaped electrodes are integrated on the channels for capacitive readout of the extremely small Coriolis displacements. The comb-shaped electrode design eliminates the need for multiple metal layers and sacrificial layer etching methods. Furthermore, it prevents squeezed film damping due to a thin layer of air between the capacitor electrodes. As a result, the sensor operates at atmospheric pressure with a quality factor in the order of 40 and does not require vacuum packaging like other micro Coriolis flow sensors. Measurement results using water, ethanol, white gas and argon are presented, showing that the sensor measures true mass flow. The measurement error is currently in the order of 1% of the full scale of 1.2 g h-1.

  11. Fault Diagnosis for Micro-Gas Turbine Engine Sensors via Wavelet Entropy

    PubMed Central

    Yu, Bing; Liu, Dongdong; Zhang, Tianhong

    2011-01-01

    Sensor fault diagnosis is necessary to ensure the normal operation of a gas turbine system. However, the existing methods require too many resources and this need can’t be satisfied in some occasions. Since the sensor readings are directly affected by sensor state, sensor fault diagnosis can be performed by extracting features of the measured signals. This paper proposes a novel fault diagnosis method for sensors based on wavelet entropy. Based on the wavelet theory, wavelet decomposition is utilized to decompose the signal in different scales. Then the instantaneous wavelet energy entropy (IWEE) and instantaneous wavelet singular entropy (IWSE) are defined based on the previous wavelet entropy theory. Subsequently, a fault diagnosis method for gas turbine sensors is proposed based on the results of a numerically simulated example. Then, experiments on this method are carried out on a real micro gas turbine engine. In the experiment, four types of faults with different magnitudes are presented. The experimental results show that the proposed method for sensor fault diagnosis is efficient. PMID:22163734

  12. Fault diagnosis for micro-gas turbine engine sensors via wavelet entropy.

    PubMed

    Yu, Bing; Liu, Dongdong; Zhang, Tianhong

    2011-01-01

    Sensor fault diagnosis is necessary to ensure the normal operation of a gas turbine system. However, the existing methods require too many resources and this need can't be satisfied in some occasions. Since the sensor readings are directly affected by sensor state, sensor fault diagnosis can be performed by extracting features of the measured signals. This paper proposes a novel fault diagnosis method for sensors based on wavelet entropy. Based on the wavelet theory, wavelet decomposition is utilized to decompose the signal in different scales. Then the instantaneous wavelet energy entropy (IWEE) and instantaneous wavelet singular entropy (IWSE) are defined based on the previous wavelet entropy theory. Subsequently, a fault diagnosis method for gas turbine sensors is proposed based on the results of a numerically simulated example. Then, experiments on this method are carried out on a real micro gas turbine engine. In the experiment, four types of faults with different magnitudes are presented. The experimental results show that the proposed method for sensor fault diagnosis is efficient.

  13. Coupled sensor/platform control design for low-level chemical detection with position-adaptive micro-UAVs

    NASA Astrophysics Data System (ADS)

    Goodwin, Thomas; Carr, Ryan; Mitra, Atindra K.; Selmic, Rastko R.

    2009-05-01

    We discuss the development of Position-Adaptive Sensors [1] for purposes for detecting embedded chemical substances in challenging environments. This concept is a generalization of patented Position-Adaptive Radar Concepts developed at AFRL for challenging conditions such as urban environments. For purposes of investigating the detection of chemical substances using multiple MAV (Micro-UAV) platforms, we have designed and implemented an experimental testbed with sample structures such as wooden carts that contain controlled leakage points. Under this general concept, some of the members of a MAV swarm can serve as external position-adaptive "transmitters" by blowing air over the cart and some of the members of a MAV swarm can serve as external position-adaptive "receivers" that are equipped with chemical or biological (chem/bio) sensors that function as "electronic noses". The objective can be defined as improving the particle count of chem/bio concentrations that impinge on a MAV-based position-adaptive sensor that surrounds a chemical repository, such as a cart, via the development of intelligent position-adaptive control algorithms. The overall effect is to improve the detection and false-alarm statistics of the overall system. Within the major sections of this paper, we discuss a number of different aspects of developing our initial MAV-Based Sensor Testbed. This testbed includes blowers to simulate position-adaptive excitations and a MAV from Draganfly Innovations Inc. with stable design modifications to accommodate our chem/bio sensor boom design. We include details with respect to several critical phases of the development effort including development of the wireless sensor network and experimental apparatus, development of the stable sensor boom for the MAV, integration of chem/bio sensors and sensor node onto the MAV and boom, development of position-adaptive control algorithms and initial tests at IDCAST (Institute for the Development and

  14. Directional emission micro-cavity lasers with different device structures

    NASA Astrophysics Data System (ADS)

    Yan, Chang-ling; Shi, Jian-wei; Feng, Yuan; Hao, Yong-qin; Li, Hui; Zhang, Jian-jia; Li, Peng; Wang, Jia-bin

    2016-10-01

    The micro-cavity lasers support the ultra-low threshold and ultrahigh Q-factor, but several disadvantages impede further development, such as isotropic far-field profile pattern and low optical power output. To overcome the intrinsic problems, several deformed structures were proposed and investigated. In this paper we present directional emission micro-cavity lasers with limason-shaped, triangle-shaped, and ellipse shaped cavity structures. In experiment, mid-infrared InGaAs/InAlAs quantum cascade material was employed to fabricate these micro-cavity lasers, due to its advantages of lack of surface recombination, and inherently in-plane with transverse magnetic (TM) mode emission. The micro-cavity lasers with different device structures were operated and compared at room temperature, and a higher output power was also achieved by increasing the device structure size.

  15. Photoacoustic probe using a micro-ring resonator ultrasonic sensor for endoscopic applications

    PubMed Central

    Dong, Biqin; Chen, Siyu; Zhang, Zhen; Sun, Cheng; Zhang, Hao F.

    2015-01-01

    We designed an all-optical photoacoustic probe for endoscopic applications by employing an optically-transparent, coverslip-type, polymeric micro-ring resonator ultrasonic sensor. We experimentally quantified the axial, tangential, and radial resolutions and angular sensitive stability of this probe. Using this probe, we achieved volumetric imaging of several phantoms. Our all-optical probe design offers clear benefit in integrating photoacoustic endoscope with other optical endoscopic imaging modalities to facilitate the transformation from bench to bedside. PMID:25078180

  16. A micro oxygen sensor based on a nano sol-gel TiO2 thin film.

    PubMed

    Wang, Hairong; Chen, Lei; Wang, Jiaxin; Sun, Quantao; Zhao, Yulong

    2014-09-03

    An oxygen gas microsensor based on nanostructured sol-gel TiO2 thin films with a buried Pd layer was developed on a silicon substrate. The nanostructured titania thin films for O2 sensors were prepared by the sol-gel process and became anatase after heat treatment. A sandwich TiO2 square board with an area of 350 μm × 350 μm was defined by both wet etching and dry etching processes and the wet one was applied in the final process due to its advantages of easy control for the final structure. A pair of 150 nm Pt micro interdigitated electrodes with 50 nm Ti buffer layer was fabricated on the board by a lift-off process. The sensor chip was tested in a furnace with changing the O2 concentration from 1.0% to 20% by monitoring its electrical resistance. Results showed that after several testing cycles the sensor's output becomes stable, and its sensitivity is 0.054 with deviation 2.65 × 10(-4) and hysteresis is 8.5%. Due to its simple fabrication process, the sensor has potential for application in environmental monitoring, where lower power consumption and small size are required.

  17. A Micro Oxygen Sensor Based on a Nano Sol-Gel TiO2 Thin Film

    PubMed Central

    Wang, Hairong; Chen, Lei; Wang, Jiaxin; Sun, Quantao; Zhao, Yulong

    2014-01-01

    An oxygen gas microsensor based on nanostructured sol-gel TiO2 thin films with a buried Pd layer was developed on a silicon substrate. The nanostructured titania thin films for O2 sensors were prepared by the sol-gel process and became anatase after heat treatment. A sandwich TiO2 square board with an area of 350 μm × 350 μm was defined by both wet etching and dry etching processes and the wet one was applied in the final process due to its advantages of easy control for the final structure. A pair of 150 nm Pt micro interdigitated electrodes with 50 nm Ti buffer layer was fabricated on the board by a lift-off process. The sensor chip was tested in a furnace with changing the O2 concentration from 1.0% to 20% by monitoring its electrical resistance. Results showed that after several testing cycles the sensor's output becomes stable, and its sensitivity is 0.054 with deviation 2.65 × 10−4 and hysteresis is 8.5%. Due to its simple fabrication process, the sensor has potential for application in environmental monitoring, where lower power consumption and small size are required. PMID:25192312

  18. A micro-cantilever sensor chip based on contact angle analysis for a label-free troponin I immunoassay.

    PubMed

    Yin, Tsung-I; Zhao, Yunpeng; Horak, Josef; Bakirci, Huseyin; Liao, Hsin-Hao; Tsai, Hann-Huei; Juang, Ying-Zong; Urban, Gerald

    2013-03-07

    Cantilever sensors have been extensively explored as a promising technique for real-time and label-free analyses in biological systems. A major sensing principle utilized by state-of-the-art cantilever sensors is based on analyte-induced surface stress changes, which result in static bending of a cantilever. The sensor performance, however, suffers from the intrinsically small change in surface stress induced by analytes, especially for molecular recognition such as antigen-antibody binding. Through the contact angle change on a tailored solid surface, it is possible to convert a tiny surface stress into a capillary force-a much larger physical quantity needed for a practical sensor application. In this work, a micro-cantilever sensor based on contact angle analysis (CAMCS) was proposed to effectively enhance the sensitivity of a sensor in proportion to the square of the length to thickness ratio of the cantilever structure. CAMCS chips were fabricated using a standard complementary-metal-oxide-semiconductor (CMOS) process to demonstrate a 1250-fold enhancement in the sensitivity of surface stress to bioanalyte adsorption using a piezoresistive sensing method. A real-time and label-free troponin I (cTnI) immunoassay, which is now widely used in clinics and considered a gold standard for the early diagnosis and prognosis of cardiovascular disease, was performed to demonstrate cTnI detection levels as low as 1 pg mL(-1). The short detection time of this assay was within several minutes, which matches the detection time of commercially available instruments that are based on fluorescence-labeling techniques.

  19. Recent Trends in Monitoring of European Water Framework Directive Priority Substances Using Micro-Sensors: A 2007–2009 Review

    PubMed Central

    Namour, Philippe; Lepot, Mathieu; Jaffrezic-Renault, Nicole

    2010-01-01

    This review discusses from a critical perspective the development of new sensors for the measurement of priority pollutants targeted in the E.U. Water Framework Directive. Significant advances are reported in the paper and their advantages and limitations are also discussed. Future perspectives in this area are also pointed out in the conclusions. This review covers publications appeared since December 2006 (the publication date of the Swift report). Among priority substances, sensors for monitoring the four WFD metals represent 81% of published papers. None of analyzed publications present a micro-sensor totally validated in laboratory, ready for tests under real conditions in the field. The researches are mainly focused on the sensing part of the micro-sensors. Nevertheless, the main factor limiting micro-sensor applications in the environment is the ruggedness of the receptor towards environmental conditions. This point constitutes the first technological obstacle to be overcome for any long-term field tests. PMID:22163635

  20. A beam-membrane structure micromachined differential pressure flow sensor

    SciTech Connect

    Chen, P.; Zhao, Y. L.; Tian, B. Li, C.; Li, Y. Y.

    2015-04-15

    A beam-membrane structure micromachined flow sensor is designed, depending on the principle of differential pressure caused by the mass flow, which is directly proportional to the square flow rate. The FSI (fluid structure interaction) characteristics of the differential pressure flow sensor are investigated via numerical analysis and analog simulation. The working mechanism of the flow sensor is analyzed depending on the FSI results. Then, the flow sensor is fabricated and calibrated. The calibration results show that the beam-membrane structure differential pressure flow sensor achieves ideal static characteristics and works well in the practical applications.

  1. Multi-sensor fusion techniques for state estimation of micro air vehicles

    NASA Astrophysics Data System (ADS)

    Donavanik, Daniel; Hardt-Stremayr, Alexander; Gremillion, Gregory; Weiss, Stephan; Nothwang, William

    2016-05-01

    Aggressive flight of micro air vehicles (MAVs) in unstructured, GPS-denied environments poses unique challenges for estimation of vehicle pose and velocity due to the noise, delay, and drift in individual sensor measurements. Maneuvering flight at speeds in excess of 5 m/s poses additional challenges even for active range sensors; in the case of LIDAR, an assembled scan of the vehicles environment will in most cases be obsolete by the time it is processed. Multi-sensor fusion techniques which combine inertial measurements with passive vision techniques and/or LIDAR have achieved breakthroughs in the ability to maintain accurate state estimates without the use of external positioning sensors. In this paper, we survey algorithmic approaches to exploiting sensors with a wide range of nonlinear dynamics using filter and bundle-adjustment based approaches for state estimation and optimal control. From this foundation, we propose a biologically-inspired framework for incorporating the human operator in the loop as a privileged sensor in a combined human/autonomy paradigm.

  2. Hydrazine leak detection using poly (3-hexylthiophene) thin film micro-sensor

    NASA Astrophysics Data System (ADS)

    Yang, H.; Wan, J.; Shu, H.; Liu, X.; Lakshmanan, R. S.; Guntupalli, R.; Hu, J.; Howard, W.; Chin, B. A.

    2006-05-01

    Hydrazine is mostly used as a propellant in the control/propulsion system of missiles, spacecraft and satellites. However with its highly toxic and strong reducing nature, hydrazine is very dangerous to humans and the environment. In this research, a low cost, passive, and highly sensitive micro-sensor has been developed as an alarm device for real-time monitoring for the accidental release of hydrazine, and to insure the safety of personnel and the readiness of the system before lift-off. The micro-sensor is fabricated using standard microelectronic manufacturing techniques and is composed of interdigitated electrodes and a hydrazine-sensitive poly (3-hexylthiophene) (P3HT) thin film. When exposed to 1ppm of hydrazine gas, the compensation interaction between the reducing hydrazine gas and p-type doped P3HT leads to a five order magnitude increase in the resistance of the device. The sensor is capable of detecting hydrazine leaks from tens of ppb to tens of ppm concentration. The sensitivity of sensor increases with the increasing of hydrazine concentration and the decreasing of the polymer film thickness. A numerical simulation result based on the possible theoretical model is compared with the experimental data, which shows a good agreement.

  3. Dynamic Structural Health Monitoring of Slender Structures Using Optical Sensors

    PubMed Central

    Antunes, Paulo; Travanca, Rui; Rodrigues, Hugo; Melo, José; Jara, José; Varum, Humberto; André, Paulo

    2012-01-01

    In this paper we summarize the research activities at the Instituto de Telecomunicações—Pólo de Aveiro and University of Aveiro, in the field of fiber Bragg grating based sensors and their applications in dynamic measurements for Structural Health Monitoring of slender structures such as towers. In this work we describe the implementation of an optical biaxial accelerometer based on fiber Bragg gratings inscribed on optical fibers. The proof-of-concept was done with the dynamic monitoring of a reinforced concrete structure and a slender metallic telecommunication tower. Those structures were found to be suitable to demonstrate the feasibility of FBG accelerometers to obtain the structures' natural frequencies, which are the key parameters in Structural Health Monitoring and in the calibration of numerical models used to simulate the structure behavior. PMID:22778661

  4. Dynamic Structural Health Monitoring of slender structures using optical sensors.

    PubMed

    Antunes, Paulo; Travanca, Rui; Rodrigues, Hugo; Melo, José; Jara, José; Varum, Humberto; André, Paulo

    2012-01-01

    In this paper we summarize the research activities at the Instituto de Telecomunicações--Pólo de Aveiro and University of Aveiro, in the field of fiber Bragg grating based sensors and their applications in dynamic measurements for Structural Health Monitoring of slender structures such as towers. In this work we describe the implementation of an optical biaxial accelerometer based on fiber Bragg gratings inscribed on optical fibers. The proof-of-concept was done with the dynamic monitoring of a reinforced concrete structure and a slender metallic telecommunication tower. Those structures were found to be suitable to demonstrate the feasibility of FBG accelerometers to obtain the structures' natural frequencies, which are the key parameters in Structural Health Monitoring and in the calibration of numerical models used to simulate the structure behavior.

  5. Sensor technology workshop: Structure and goals

    NASA Technical Reports Server (NTRS)

    Wilson, Barbara A.

    1991-01-01

    The Astrotech 21 charter for the second of three workshops is described. The purpose was to identify technology needs in the areas of electromagnetic radiation sensors, and to recommend a plan to develop the required capabilities that are not currently available. The panels chosen for this workshop focused specifically on those technologies needed for the Astrotech 21 Program including: gamma ray and x ray sensors, ultraviolet and visible sensors, direct infrared sensors, and heterodyne submillimeter wave sensors.

  6. Elemental analyses of hypervelocity micro-particle impact sites on interplanetary dust experiment sensor surfaces

    NASA Technical Reports Server (NTRS)

    Simon, Charles G.; Hunter, J. L.; Griffis, D. P.; Misra, V.; Ricks, D. R.; Wortman, Jim J.

    1992-01-01

    The Interplanetary Dust Experiment (IDE) had over 450 electrically active ultra-high purity metal-oxide-silicon impact detectors located on the six primary sides of the Long Duration Exposure Facility (LDEF). Hypervelocity micro-particles that struck the active sensors with enough energy to breakdown the 0.4 to 1.0 micron thick SiO2 insulator layer separating the silicon base (the negative electrode), and the 1000 A thick surface layer of aluminum (the positive electrode) caused electrical discharges that were recorded for the first year of orbit. These discharge features, which include 50 micron diameter areas where the aluminum top layer has been vaporized, facilitate the location of the impacts. The high purity Al-SiO2-Si substrates allow detection of trace (ppm) amounts of hypervelocity impactor residues. After sputtering through a layer of surface contamination, secondary ion mass spectrometry (SIMS) is used to create two-dimensional elemental ion intensity maps of micro-particle impact sites on the IDE sensors. The element intensities in the central craters of the impacts are corrected for relative ion yields and instrumental conditions and then normalized to silicon. The results are used to classify the particles' origins as 'manmade', 'natural' or 'indeterminate'. The last classification results from the presence of too little impactor residue (a frequent occurrence on leading edge impacts), analytical interference from high background contamination, the lack of information on silicon residue, the limited usefulness of data on aluminum in the central craters, or a combination of these circumstances. Several analytical 'blank' discharges were induced on flight sensors by pressing down on the sensor surface with a pure silicon shard. Analyses of these blank discharges showed that the discharge energy blasts away the layer of surface contamination. Only Si and Al were detected inside the discharge zones, including the central craters, of these features. A

  7. Photonic Crystal Structures with Tunable Structure Color as Colorimetric Sensors

    PubMed Central

    Wang, Hui; Zhang, Ke-Qin

    2013-01-01

    Colorimetric sensing, which transduces environmental changes into visible color changes, provides a simple yet powerful detection mechanism that is well-suited to the development of low-cost and low-power sensors. A new approach in colorimetric sensing exploits the structural color of photonic crystals (PCs) to create environmentally-influenced color-changeable materials. PCs are composed of periodic dielectrics or metallo-dielectric nanostructures that affect the propagation of electromagnetic waves (EM) by defining the allowed and forbidden photonic bands. Simultaneously, an amazing variety of naturally occurring biological systems exhibit iridescent color due to the presence of PC structures throughout multi-dimensional space. In particular, some kinds of the structural colors in living organisms can be reversibly changed in reaction to external stimuli. Based on the lessons learned from natural photonic structures, some specific examples of PCs-based colorimetric sensors are presented in detail to demonstrate their unprecedented potential in practical applications, such as the detections of temperature, pH, ionic species, solvents, vapor, humidity, pressure and biomolecules. The combination of the nanofabrication technique, useful design methodologies inspired by biological systems and colorimetric sensing will lead to substantial developments in low-cost, miniaturized and widely deployable optical sensors. PMID:23539027

  8. Photonic crystal structures with tunable structure color as colorimetric sensors.

    PubMed

    Wang, Hui; Zhang, Ke-Qin

    2013-03-28

    Colorimetric sensing, which transduces environmental changes into visible color changes, provides a simple yet powerful detection mechanism that is well-suited to the development of low-cost and low-power sensors. A new approach in colorimetric sensing exploits the structural color of photonic crystals (PCs) to create environmentally-influenced color-changeable materials. PCs are composed of periodic dielectrics or metallo-dielectric nanostructures that affect the propagation of electromagnetic waves (EM) by defining the allowed and forbidden photonic bands. Simultaneously, an amazing variety of naturally occurring biological systems exhibit iridescent color due to the presence of PC structures throughout multi-dimensional space. In particular, some kinds of the structural colors in living organisms can be reversibly changed in reaction to external stimuli. Based on the lessons learned from natural photonic structures, some specific examples of PCs-based colorimetric sensors are presented in detail to demonstrate their unprecedented potential in practical applications, such as the detections of temperature, pH, ionic species, solvents, vapor, humidity, pressure and biomolecules. The combination of the nanofabrication technique, useful design methodologies inspired by biological systems and colorimetric sensing will lead to substantial developments in low-cost, miniaturized and widely deployable optical sensors.

  9. A radar unattended ground sensor with micro-Doppler capabilities for false alarm reduction

    NASA Astrophysics Data System (ADS)

    Tahmoush, Dave; Silvious, Jerry; Burke, Ed

    2010-10-01

    Unattended ground sensors (UGS) provide the capability to inexpensively secure remote borders and other areas of interest. However, the presence of normal animal activity can often trigger a false alarm. Accurately detecting humans and distinguishing them from natural fauna is an important issue in security applications to reduce false alarm rates and improve the probability of detection. In particular, it is important to detect and classify people who are moving in remote locations and transmit back detections and analysis over extended periods at a low cost and with minimal maintenance. We developed and demonstrate a compact radar technology that is scalable to a variety of ultra-lightweight and low-power platforms for wide area persistent surveillance as an unattended, unmanned, and man-portable ground sensor. The radar uses micro-Doppler processing to characterize the tracks of moving targets and to then eliminate unimportant detections due to animals as well as characterize the activity of human detections. False alarms from sensors are a major liability that hinders widespread use. Incorporating rudimentary intelligence into sensors can reduce false alarms but can also result in a reduced probability of detection. Allowing an initial classification that can be updated with new observations and tracked over time provides a more robust framework for false alarm reduction at the cost of additional sensor observations. This paper explores these tradeoffs with a small radar sensor for border security. Multiple measurements were done to try to characterize the micro-Doppler of human versus animal and vehicular motion across a range of activities. Measurements were taken at the multiple sites with realistic but low levels of clutter. Animals move with a quadrupedal motion, which can be distinguished from the bipedal human motion. The micro-Doppler of a vehicle with rotating parts is also shown, along with ground truth images. Comparisons show large variations for

  10. Wireless sensor systems and methods, and methods of monitoring structures

    DOEpatents

    Kunerth, Dennis C.; Svoboda, John M.; Johnson, James T.; Harding, L. Dean; Klingler, Kerry M.

    2007-02-20

    A wireless sensor system includes a passive sensor apparatus configured to be embedded within a concrete structure to monitor infiltration of contaminants into the structure. The sensor apparatus includes charging circuitry and a plurality of sensors respectively configured to measure environmental parameters of the structure which include information related to the infiltration of contaminants into the structure. A reader apparatus is communicatively coupled to the sensor apparatus, the reader apparatus being configured to provide power to the charging circuitry during measurements of the environmental parameters by the sensors. The reader apparatus is configured to independently interrogate individual ones of the sensors to obtain information measured by the individual sensors. The reader apparatus is configured to generate an induction field to energize the sensor apparatus. Information measured by the sensor apparatus is transmitted to the reader apparatus via a response signal that is superimposed on a return induction field generated by the sensor apparatus. Methods of monitoring structural integrity of the structure are also provided.

  11. Fabrication of structured micro and nanofibers by coaxial electrospinning

    NASA Astrophysics Data System (ADS)

    Díaz, J. E.; Fernández-Nieves, A.; Barrero, A.; Márquez, M.; Loscertales, I. G.

    2008-08-01

    Among the different ways of synthesizing fiber and tubular micro and nanostructures, some top-down methods resort to electro-hydrodynamic forces to smoothly stretch liquids interfaces down to such small size scales. The well-known electrospinning technique, commonly used to fabricate micro and nanofibers of a broad variety of materials, is now expanded to fabricate coaxial fibers upon the generation of electrified coaxial jets instead of single jets. We briefly report different types of micro and nano structures that may be fabricated with this new technique termed co-electrospinning.

  12. Micro-electro-mechanical system (MEMS)-based fiber optic sensor and sensor network for improving weapon stabilization and fire control

    NASA Astrophysics Data System (ADS)

    Zhang, Sean Z.; Xu, Guoda; Qiu, Wei; Lin, Freddie S.; Testa, Robert C.; Mattice, Michael S.

    2000-08-01

    A MicroElectroMechanical Systems (MEMS)-based fiber optic sensor and sensor network for improving weapon stabilization and fire control have been developed. Fabrication involves overwriting two fiber Bragg gratings (FBGs) onto a polarization-preserving optical fiber core. A MEMS diaphragm is fabricated and integrated with the overlaid FBGs to enhance the performance and reliability of the sensor. A simulation model for the MEMS fiber optic sensor and sensor network has been derived, and simulation results concerning load, angle, strain, and temperature have been obtained. The fabricated MEMS diaphragm and the overlaid FBGs have been packaged together on the basis of simulation results and mounted on a specially designed cantilever system. The combined multifunctional MEMS fiber optic sensor and sensor network is cost-effective, fast, rugged enough to operate in harsh environmental conditions, compact, and highly sensitive.

  13. A Diamond Electron Tunneling Micro-Electromechanical Sensor

    NASA Technical Reports Server (NTRS)

    Albin, Sacharia

    2000-01-01

    A new pressure sensing device using field emission from diamond coated silicon tips has been developed. A high electric field applied between a nano-tip array and a diaphragm configured as electrodes produces electron emission governed by the Fowler Nordheim equation. The electron emission is very sensitive to the separation between the diaphragm and the tips, which is fixed at an initial spacing and bonded such that a cavity is created between them. Pressure applied to the diaphragm decreases the spacing between the electrodes, thereby increasing the number of electrons emitted. Silicon has been used as a substrate on which arrays of diamond coated sharp tips have been fabricated for electron emission. Also, a diaphragm has been made using wet orientation dependent etching. These two structures were bonded together using epoxy and tested. Current - voltage measurements were made at varying pressures for 1-5 V biasing conditions. The sensitivity was found to be 2.13 mV/V/psi for a 20 x 20 array, which is comparable to that of silicon piezoresistive transducers. Thinner diaphragms as well as alternative methods of bonding are expected to improve the electrical characteristics of the device. This transducer will find applications in many engineering fields for pressure measurement.

  14. Bayesian Computational Sensor Networks for Aircraft Structural Health Monitoring

    DTIC Science & Technology

    2016-02-02

    AFRL-AFOSR-VA-TR-2016-0094 Bayesian Computational Sensor Networks for Aircraft Structural Health Monitoring. Thomas Henderson UNIVERSITY OF UTAH SALT...The major goal of this work was to provide rigorous Bayesian Computational Sensor Networks to quantify uncertainty in (1) model-based state...estimates incorporating sensor data, (2) model parameters (e.g., diffusion coefficients), (3) sensor node model parameter values (e.g., location, bias

  15. Optical fiber sensors for materials and structures characterization

    NASA Technical Reports Server (NTRS)

    Lindner, D. K.; Claus, R. O.

    1991-01-01

    The final technical report on Optical Fiber Sensors for Materials and Structures Characterization, covering the period August 1990 through August 1991 is presented. Research programs in the following technical areas are described; sapphire optical fiber sensors; vibration analysis using two-mode elliptical core fibers and sensors; extrinsic Fabry-Perot interferometer development; and coatings for fluorescent-based sensor. Research progress in each of these areas was substantial, as evidenced by the technical publications which are included as appendices.

  16. Nano- and micro-structured silicon for hybrid near-infrared photodetectors

    NASA Astrophysics Data System (ADS)

    Äńerek, V.; Głowacki, E. D.; Bednorz, M.; Demchyshyn, S.; Sariciftci, N. S.; Ivanda, M.

    2016-05-01

    Structuring surface and bulk of crystalline silicon on different length scales can significantly alter its properties and possibly improve the performance of opto-electronic devices and sensors based on silicon. Different dominant feature scales are responsible for modification of some of electronic and optical properties of silicon. Several easily reproducible chemical methods for facile structuring of silicon on nano and micro-scales, based on both electroless and anodic etching of silicon in hydrofluoric acid based etchants, and chemical anisotropic etching of silicon in basic environments, are presented. We show how successive micro and nano structuring creates hierarchical silicon surfaces, which can be used to simultaneously exploit the advantages of both structuring feature length scales. Finally, we demonstrate a large increase in photocurrent obtained from a hybrid structured silicon/organic near-infrared photodetector. Improved silicon/6,6'-dibromoindigo hybrid photodiodes were prepared by nano- and micro-structuring the silicon part of the heterojunction by wet chemical etching methods. Photocurrent and spectral responsivity were improved in comparison to planar diodes by up to two orders of magnitude by optimization of the silicon structuring process. We show that the improvement in photocurrent is not due to the increase in surface area or light trapping.

  17. Topography measurement of micro structure by modulation-based method

    NASA Astrophysics Data System (ADS)

    Zhou, Yi; Tang, Yan; Liu, Junbo; Deng, Qinyuan; Cheng, Yiguang; Hu, Song

    2016-10-01

    Dimensional metrology for micro structure plays an important role in addressing quality issues and observing the performance of micro-fabricated products. Different from the traditional white-light interferometry approach, the modulation-based method is expected to measure topography of micro structure by the obtained modulation of each interferometry image. Through seeking the maximum modulation of every pixel respectively in Z direction, the method could obtain the corresponding height of individual pixel and finally get topography of the structure. Owing to the characteristic of modulation, the proposed method which is not influenced by the change of background light intensity caused by instable light source and different reflection index of the structure could be widely applied with high stability. The paper both illustrates the principle of this novel method and conducts the experiment to verify the feasibility.

  18. Xenon Additives Detection in Helium Micro-Plasma Gas Analytical Sensor

    NASA Astrophysics Data System (ADS)

    Tsyganov, Alexander; Kudryavtsev, Anatoliy; Mustafaev, Alexander

    2012-10-01

    Electron energy spectra of Xe atoms at He filled micro-plasma afterglow gas analyzer were observed using Collisional Electron Spectroscopy (CES) method [1]. According to CES, diffusion path confinement for characteristic electrons makes it possible to measure electrons energy distribution function (EEDF) at a high (up to atmospheric) gas pressure. Simple geometry micro-plasma CES sensor consists of two plane parallel electrodes detector and microprocessor-based acquisition system providing current-voltage curve measurement in the afterglow of the plasma discharge. Electron energy spectra are deduced as 2-nd derivative of the measured current-voltage curve to select characteristic peaks of the species to be detected. Said derivatives were obtained by the smoothing-differentiating procedure using spline least-squares approximation of a current-voltage curve. Experimental results on CES electron energy spectra at 10-40 Torr in pure He and in admixture with 0.3% Xe are discussed. It demonstrates a prototype of the new miniature micro-plasma sensors for industry, safety and healthcare applications. [1]. A.A.Kudryavtsev, A.B.Tsyganov. US Patent 7,309,992. Gas analysis method and ionization detector for carrying out said method, issued December 18, 2007.

  19. Shape deposition manufacturing of smart metallic structures with embedded sensors

    NASA Astrophysics Data System (ADS)

    Li, Xiaochun; Golnas, Anastasios; Prinz, Fritz B.

    2000-06-01

    The need to obtain information on the performance and lifetime of a tool in service is of prime importance to many industries. It calls for on-line acquisition of information such as temperature and strain values from tools and structures. With embedded sensors, structures are capable of monitoring parameters at critical locations not accessible to ordinary sensors. To embed sensors in the functional structures, especially structures, Shape Deposition Manufacturing (SDM) is a methodology capable of integrating sensors during the production of tooling or structural components. Thin film sensors and fiber optic sensors have been identified as two promising candidates to be integrated in metallic structures. Embedded thin film strain gages have been characterized in a four-point bending test and the results, showing linearity and no hysteresis, match with those from the theoretical model and commercially available strain gages. Fiber optic sensors have been successfully embedded in nickel and stainless steel structures. The embedded fiber optic sensors have been used to measure temperatures and strains. They provide higher sensitivity, good accuracy, and high temperature capacity. Based on fiber optic sensor embedding techniques, a remote temperature/strain sensing system suitable rotating objects, such as turbine blades, has been developed. The developed techniques can be harnessed for rapid prototyping of smart metallic structures.

  20. Vacuum isostatic micro molding of diffractive structures into PTFE materials

    NASA Astrophysics Data System (ADS)

    Lizotte, Todd E.; Ohar, Orest

    2007-09-01

    Polytetrafluoroethylene (PTFE) is an ideal material for use in industrial, automotive and consumer electronics. Specifically, PTFE has outstanding physical properties; such as chemical inertness and resistance to chemical corrosion, even when exposed to a strong acid, alkali and oxidants. Its properties provide for superior electrical insulation and thermal stability, which is not affected by wide ranges in temperature and frequency. Its non-absorption of moisture makes it a perfect material for consideration in micro optical, retro-reflector or diffuser type devices used in handheld displays, flat panel displays as well as automotive, industrial and home lighting. This paper presents an overview of a unique fabrication method that incorporates a variety of elements to establish a processing technique that can form micro diffractive, holographic and reflective structures into PTFE materials. By means of modifying an existing known molding process, this new technique incorporates the addition of a vacuum to assist in the reliable molding and densification of the PTFE as well the use of a micro-structured electroformed shim to form small microstructures into the surface of the PTFE material. The combination of the vacuum and the electroformed shim within the molding process noticeably increases the precision, reproducibility and resolution of micro-structures that can be realized. The paper will describe the molding hardware involved, process parameters and the resulting structures formed. Optical function testing and metrology of the micro-structure geometry formed on each sample will be compared to the original design mandrel geometry [1].

  1. Motion compensation for structured light sensors

    NASA Astrophysics Data System (ADS)

    Biswas, Debjani; Mertz, Christoph

    2015-05-01

    In order for structured light methods to work outside, the strong background from the sun needs to be suppressed. This can be done with bandpass filters, fast shutters, and background subtraction. In general this last method necessitates the sensor system to be stationary during data taking. The contribution of this paper is a method to compensate for the motion if the system is moving. The key idea is to use video stabilization techniques that work even if the illuminator is switched on and off from one frame to another. We used OpenCV functions and modules to implement a robust and efficient method. We evaluated it under various conditions and tested it on a moving robot outdoors. We will demonstrate that one can not only do 3D reconstruction under strong ambient light, but that it is also possible to observe optical properties of the objects in the environment.

  2. Combining micro-structures and micro-algae to increase lipid production for bio-fuel

    NASA Astrophysics Data System (ADS)

    Vyawahare, Saurabh; Zhu, Emilly; Mestler, Troy; Estévez-Torres, André.; Austin, Robert

    2011-03-01

    3rd generation bio-fuels like lipid producing micro-algae are a promising source of energy that could replace our dependence on petroleum. However, until there are improvements in algae oil yields, and a reduction in the energy needed for processing, algae bio-fuels are not economically competitive with petroleum. Here, we describe our work combining micro-fabricated devices with micro-algae Neochloris oleoabundans, a species first isolated on the sand dunes of Saudi Arabia. Inserting micro-algae of varying fitness into a landscape of micro-habitats allows us to evolve and select them based on a variety of conditions like specific gravity, starvation response and Nile Red fluorescence (which is a marker for lipid production). Hence, we can both estimate the production of lipids and generate conditions that allow the creation and isolation of algae which produce higher amounts of lipids, while discarding the rest. Finally, we can use micro-fabricated structures and flocculation to de-water these high lipid producing algae, reducing the need for expensive centrifugation and filtration.

  3. A planar lightwave circuit based micro interrogator and its applications to the interrogation of multiplexed optical fiber Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Xiao, Gaozhi; Mrad, Nezih; Guo, Honglei; Zhang, Zhiyi; Yao, Jianping

    2008-12-01

    Optical fiber Bragg grating sensors have found potential applications in many fields, but the lack of a simple, field deployable and low cost interrogation system is hindering their deployment. To tackle this, we have developed a micro optical sensor interrogator using a monolithically integrated planar lightwave circuit based echelle diffractive grating demultiplexer and a detector array. The design and development of this device are presented in this paper. It has been found that the measurement range of this micro interrogator is more than 25 nm with better than 1 pm resolution. This paper also reports the applications of the micro interrogator developed to the monitoring of commercial optical fiber Bragg grating (FBG) temperature sensors and mechanical sensors. The results obtained are very satisfactory and in some cases, they are better than those obtained using commercial bench top lab equipment.

  4. Applicability of New Approaches of Sensor Orientation to Micro Aerial Vehicles

    NASA Astrophysics Data System (ADS)

    Rehak, M.; Skaloud, J.

    2016-06-01

    This study highlights the benefits of precise aerial position and attitude control in the context of mapping with Micro Aerial Vehicles (MAVs). Accurate mapping with MAVs is gaining importance in applications such as corridor mapping, road and pipeline inspections or mapping of large areas with homogeneous surface structure, e.g. forests or agricultural fields. There, accurate aerial control plays a major role in successful terrain reconstruction and artifact-free ortophoto generation. The presented experiments focus on new approaches of aerial control. We confirm practically that the relative aerial position and attitude control can improve accuracy in difficult mapping scenarios. Indeed, the relative orientation method represents an attractive alternative in the context of MAVs for two reasons. First, the procedure is somewhat simplified, e.g. the angular misalignment, so called boresight, between the camera and the inertial measurement unit (IMU) does not have to be determined and, second, the effect of possible systematic errors in satellite positioning (e.g. due to multipath and/or incorrect recovery of differential carrier-phase ambiguities) is mitigated. First, we present a typical mapping project over an agricultural field and second, we perform a corridor road mapping. We evaluate the proposed methods in scenarios with and without automated image observations. We investigate a recently proposed concept where adjustment is performed using image observations limited to ground control and check points, so called fast aerial triangulation (Fast AT). In this context we show that accurate aerial control (absolute or relative) together with a few image observations can deliver accurate results comparable to classical aerial triangulation with thousands of image measurements. This procedure in turns reduces the demands on processing time and the requirements on the existence of surface texture. Finally, we compare the above mentioned procedures with direct sensor

  5. Formation of micro/nano structures out of soap bubbles

    NASA Astrophysics Data System (ADS)

    Bai, Xiao-Dan; Liu, Jing

    2007-07-01

    We proposed to synthesize, etch and construct micro/nano structures through manipulating the large-scale bubbles composed of specific chemical compounds. The core of the method lies in the chemical reaction occurred at the interfaces between two or more soap bubbles. A unique virtue of the bubble is that it can have a rather large diameter however an extremely small membrane thickness, whose smallest size could reach nano scale. Therefore, the chemical reaction and synthesis occurred in the common interface of such contacting bubbles would lead to products with very small size. Several typical micro structures were fabricated to demonstrate the feasibility of the new method. Being flexible, easily controllable and environment friendly, the present concept may open a straightforward low-cost way for making micro/nano structures.

  6. Vibrating Makes for Better Seeing: From the Fly's Micro-Eye Movements to Hyperacute Visual Sensors.

    PubMed

    Viollet, Stéphane

    2014-01-01

    Active vision means that visual perception not only depends closely on the subject's own movements, but that these movements actually contribute to the visual perceptual processes. Vertebrates' and invertebrates' eye movements are probably part of an active visual process, but their exact role still remains to be determined. In this paper, studies on the retinal micro-movements occurring in the compound eye of the fly are reviewed. Several authors have located and identified the muscles involved in these small retinal movements. Others have established that these retinal micro-movements occur in walking and flying flies, but their exact functional role still remains to be determined. Many robotic studies have been performed in which animals' (flies' and spiders') miniature eye movements have been modeled, simulated, and even implemented mechanically. Several robotic platforms have been endowed with artificial visual sensors performing periodic micro-scanning movements. Artificial eyes performing these active retinal micro-movements have some extremely interesting properties, such as hyperacuity and the ability to detect very slow movements (motion hyperacuity). The fundamental role of miniature eye movements still remains to be described in detail, but several studies on natural and artificial eyes have advanced considerably toward this goal.

  7. A simple microfluidic integrated with an optical sensor for micro flow injection colorimetric determination of glutathione.

    PubMed

    Supharoek, Sam-ang; Youngvises, Napaporn; Jakmunee, Jaroon

    2012-01-01

    A simple and inexpensive method for fabricating a microfluidic platform was developed. A printed circuit board (PCB) was used to make a master mold for replicating a polydimethylsiloxane (PDMS) microchannel. The master mold was fabricated by a simple photolithographic method, employing a photoresist dry film. The process did not use hazardous chemicals, a clean room or any expensive instrument. The PDMS microchannel was clamped with polymethylmethacrylate (PMMA) plates, where a light emitting diode (LED) as a light source and a light dependent resistor (LDR) as a light sensor were attached to form a simple optical sensor. The system was successfully employed as a micro flow injection analysis for the determination of glutathione in dietary supplement samples. A linear calibration graph in the range of 5.0 - 60.0 mg L(-1) glutathione was obtained with a detection limit of 0.01 mg L(-1). The system provided a sample throughput of 48 h(-1), with microliter consumption of the reagent.

  8. A 16-bit sigma-delta ADC applied in micro-machined inertial sensor

    NASA Astrophysics Data System (ADS)

    Qiang, Li; Xiaowei, Liu

    2015-04-01

    This paper presents a low-distortion sigma-delta (Σ-Δ) ADC for micro-machined inertial sensors. The design adopts a single-loop, fourth-order low-pass single-bit modulator with feedforward paths which can ensure the signal transfer lossless and reduce the nonlinearity and power consumption. The chip is manufactured in standard 0.5µm CMOS process, and the area is 2.2mm2. The ADC achieves 108dB signal to noise ratio (SNR) and 110dB dynamic range (DR). Total power consumption is less than 15mW with 5V supply.

  9. Efficient sensor placement for state estimation in structural dynamics

    NASA Astrophysics Data System (ADS)

    Hernandez, Eric M.

    2017-02-01

    This paper derives a computationally efficient algorithm to determine optimal sequential sensor placement for state estimation in linear structural systems subjected to unmeasured excitations and noise contaminated measurements. The proposed algorithm is developed within the context of the Kalman filter and it minimizes the variance of the state estimate among all possible sequential sensor locations. The paper investigates the effects of measurement type, covariance matrix partition selection, spatial correlation of excitation and model selection on optimal sensor placement. The paper shows that the sequential approach reaches the optimal sensor placement as the number of sensor increases.

  10. Test Structures Applied to the Rapid Prototyping of Sensors

    NASA Technical Reports Server (NTRS)

    Buehler, M.; Chang, L-J.; Martin, D.

    1997-01-01

    Recently, test structures were used to aid in the rapid development of a gas sensor and pressure sensor. These sensors were fabricated using co-fired ceramic technology and a multiproject approach. This talk will describe results obtained from a ceramic substrate which contained 36 chips with six variants including the sensors, process control monitors, and an interconnect chip. As far as the authors know, this is the first implementation of multi-projects in co-fired ceramic substrate. The gas sensor is being developed for the Space Shuttle and the pressure gage is being developed as a Martian barometer.

  11. Structural Health Monitoring Sensor Development at NASA Langley Research Center

    NASA Technical Reports Server (NTRS)

    Prosser, W. H.; Wu, M. C.; Allison, S. G.; DeHaven, S. L.; Ghoshal, A.

    2002-01-01

    NASA is applying considerable effort on the development of sensor technology for structural health monitoring (SHM). This research is targeted toward increasing the safety and reliability of aerospace vehicles, while reducing operating and maintenance costs. Research programs are focused on applications to both aircraft and space vehicles. Sensor technologies under development span a wide range including fiber-optic sensing, active and passive acoustic sensors, electromagnetic sensors, wireless sensing systems, MEMS, and nanosensors. Because of their numerous advantages for aerospace applications, fiber-optic sensors are one of the leading candidates and are the major focus of this presentation. In addition, recent advances in active and passive acoustic sensing will also be discussed.

  12. Magnetic Micro/Nano Structures for Biological Manipulation

    NASA Astrophysics Data System (ADS)

    Huang, Chen-Yu; Hsieh, Teng-Fu; Chang, Wei-Chieh; Yeh, Kun-Chieh; Hsu, Ming-Shinn; Chang, Ching-Ray; Chen, Jiann-Yeu; Wei, Zung-Hang

    2016-05-01

    Biomanipulation based on micro/nano structures is an attractive approach for biotechnology. To manipulate biological systems by magnetic forces, the magnetic labeling technology utilized magnetic nanoparticles (MNPs) as a common rule. Ferrofluid, well-dispersed MNPs, can be used for magnetic modification of the surface or as molds to form organized microstructures. For magnetic-based micro/nano structures, different methods to modulate magnetic field at the microscale have been developed. Specifically, this review focused on a new strategy which uses the concept of micromagnetism of patterned magnetic thin film with specific domain walls configurations to generate stable magnetic poles for cell patterning.

  13. Ferroelectric domain engineering and micro-structuring of lithium niobate

    NASA Astrophysics Data System (ADS)

    Mailis, Sakellaris

    2010-11-01

    This paper discusses a number of recently developed all optical and optically assisted methods for ferroelectric domain engineering in lithium niobate and their impact on the micro-structuring of this optical ferroelectric crystal. Optical radiation is used to change the response of lithium niobate crystals to externally applied electric field encouraging or inhibiting ferroelectric domain inversion in a simultaneous or latent manner. Optically assisted poling processes have the advantage of producing ferroelectric domains with arbitrary shapes free from crystal symmetry restrictions which is very important for fabricating surface micro/nano-structures in this material.

  14. Formation of titanium carbide coating with micro-porous structure

    NASA Astrophysics Data System (ADS)

    Luo, Yong; Ge, Shirong; Jin, Zhongmin; Fisher, John

    2010-03-01

    Micro-porous titanium carbide coating was successfully synthesized in a vacuum gas carburizing furnace by using a sequential diffusion technology. The composition and structure of the as-synthesized TiC were examined by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and glow discharge mass spectrometry (GDMS), and scanning electron microscopy (SEM). All of the XRD, XPS and GDMS analysis results indicate that carbon atoms effectively diffused into the titanium alloys and formed a uniform acicular TiC coating with micro-porous structure.

  15. Local structure of ZnO micro flowers and nanoparticles obtained by micro segmented flow synthesis

    SciTech Connect

    Li, Shuning; Roy, Amitava; Lichtenberg, Henning; Merchan, Gregory; Kumar, Challa S.S.R.; Köhler, J. Michael

    2012-03-07

    The micro-segmented flow technique was applied for continuous synthesis of ZnO micro- and nanoparticles with short residence times of 9.4 s and 21.4 s, respectively. The obtained particles were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Small angle X-ray scattering (SAXS) and photoluminescence spectroscopy were used to determine the size and optical properties of ZnO nanoparticles. In addition, extended X-ray absorption fine structure (EXAFS) spectroscopy was employed to investigate local structural properties. The EXAFS measurements reveal a larger degree of structural disorder in the nanoparticles than the microparticles. These structural changes should be taken into consideration while evaluating the size-dependent visible emission of ZnO nanoparticles.

  16. An intrinsic fiber-optic single loop micro-displacement sensor.

    PubMed

    Martinez-Rios, Alejandro; Monzon-Hernandez, David; Torres-Gomez, Ismael; Salceda-Delgado, Guillermo

    2012-01-01

    A micro-displacement sensor consisting of a fiber-loop made with a tapered fiber is reported. The sensor operation is based on the interaction between the fundamental cladding mode propagating through the taper waist and higher order cladding modes excited when the taper is deformed to form a loop. As a result, a transmission spectrum with several notches is observed, where the notch wavelength resonances shift as a function of the loop diameter. The loop diameter is varied by the spatial displacement of one end of the fiber-loop attached to a linear translation stage. In a displacement range of 3.125 mm the maximum wavelength shift is 360.93 nm, with 0.116 nm/μm sensitivity. By using a 1,280 nm broadband low-power LED source and a single Ge-photodetector in a power transmission sensor setup, a sensitivity in the order of 2.7 nW/μm is obtained in ≈ 1 mm range. The proposed sensor is easy to implement and has a plenty of room to improve its performance.

  17. Fiber optic sensor reliability issues in structural health monitoring

    NASA Astrophysics Data System (ADS)

    Xu, Zhihong; Bassam, Asadollah; Jia, Hongqiang; Tennant, Adam; Ansari, Farhad

    2005-05-01

    Reliability is an important aspect of any sensor, and especially in terms of long term monitoring of structures. Some issues pertaining to the reliability of optical fiber sensors in civil structures are discussed in this article. The strength and fatigue properties of optical fibers influence their performance, and life span. Lessons learnt from the reliability of optical fibers in the telecommunication industry are useful for assessment of reliability in optical fiber sensors. However, optical fiber sensors go through additional manufacturing steps, handling processes, and in general operate under environmental conditions and stress levels different from the telecommunication lines. In general, optical fiber sensors in structures are subjected to fatigue loading under high stresses. Other reliability concerns pertain to the effects of the packaging, installation issues at the construction site. These issues along with some of the results acquired from fatigue tests on fiber optic Bragg gratings and long gauge interferometric sensors are discussed in this article.

  18. Micro Humidity Sensor with High Sensitivity and Quick Response/Recovery Based on ZnO/TiO2 Composite Nanofibers

    NASA Astrophysics Data System (ADS)

    Xu, Lei; Wang, Rui; Xiao, Qi; Zhang, Dan; Liu, Yong

    2011-07-01

    ZnO/TiO2 composite nanofibers are synthesized by an electrospinning method and characterized by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. A micro humidity sensor is fabricated by spinning the precursors of these nanofibers on a ceramic substrate with Ag-Pd interdigitated electrodes. Humidity sensing investigation reveals that this micro sensor offers high sensitivity and quick response/recovery at an operating frequency of 100Hz. The corresponding impedance changes more than four orders of magnitude within the whole humidity range from 10% to 90% relative humidity (RH), and the response and recovery times are about 4 and 12 s, respectively. The maximum hysteresis is around 2% RH. The humidity sensing mechanism is also discussed based on the nanofiber structure and morphology.

  19. Aircraft Aerodynamic Parameter Detection Using Micro Hot-Film Flow Sensor Array and BP Neural Network Identification

    PubMed Central

    Que, Ruiyi; Zhu, Rong

    2012-01-01

    Air speed, angle of sideslip and angle of attack are fundamental aerodynamic parameters for controlling most aircraft. For small aircraft for which conventional detecting devices are too bulky and heavy to be utilized, a novel and practical methodology by which the aerodynamic parameters are inferred using a micro hot-film flow sensor array mounted on the surface of the wing is proposed. A back-propagation neural network is used to model the coupling relationship between readings of the sensor array and aerodynamic parameters. Two different sensor arrangements are tested in wind tunnel experiments and dependence of the system performance on the sensor arrangement is analyzed. PMID:23112638

  20. Aircraft aerodynamic parameter detection using micro hot-film flow sensor array and BP neural network identification.

    PubMed

    Que, Ruiyi; Zhu, Rong

    2012-01-01

    Air speed, angle of sideslip and angle of attack are fundamental aerodynamic parameters for controlling most aircraft. For small aircraft for which conventional detecting devices are too bulky and heavy to be utilized, a novel and practical methodology by which the aerodynamic parameters are inferred using a micro hot-film flow sensor array mounted on the surface of the wing is proposed. A back-propagation neural network is used to model the coupling relationship between readings of the sensor array and aerodynamic parameters. Two different sensor arrangements are tested in wind tunnel experiments and dependence of the system performance on the sensor arrangement is analyzed.

  1. Experimental study of PDMS mechanical properties for the optimization of polymer based flexible pressure micro-sensors

    NASA Astrophysics Data System (ADS)

    Dinh, T. H. N.; Martincic, E.; Dufour-Gergam, E.; Joubert, P.-Y.

    2016-10-01

    This paper reports on the optimization of flexible PDMS-based normal pressure capacitive micro-sensors dedicated to wearable applications. The deformation under a normal force of PDMS thin films of thicknesses ranging from 40 μm to 10 mm is firstly experimentally studied. This study points out that for capacitive micro-sensors using bulky PDMS thin films as deformable dielectric material, the sensitivity to an applied normal load can be optimized thanks to an adequate choice of the so-called form ratio of the involved PDMS thin film. Indeed, for capacitive micro-sensors exhibiting 9 mm2 electrodes, the capacitance change under a 6 N load can be adjusted from a few percent up to over 35% according to the choice of the load-free thickness of the used PDMS film. These results have been validated thanks to electromechanical characterizations carried out on two flexible PDMS based capacitive normal pressure micro-sensor samples fabricated with two different thicknesses. The obtained results open the way to the enhanced design of PDMS based pressure sensors dedicated to wearable and medical applications. Further works will extend this study to a wider range of sensor dimensions, and using numerical modelling.

  2. VOPcPhO:P3HT composite micro-structures with nano-porous surface morphology

    NASA Astrophysics Data System (ADS)

    Azmer, Mohamad Izzat; Ahmad, Zubair; Sulaiman, Khaulah; Touati, Farid; Bawazeer, Tahani M.; Alsoufi, Mohammad S.

    2017-03-01

    In this paper, composite micro-structures of Vanadyl 2,9,16,23-tetraphenoxy-29H,31H-phthalocyanine) (VOPcPhO) and Poly (3-hexylthiophene-2,5-diyl) (P3HT) complex with nano-porous surface morphology have been developed by electro-spraying technique. The structural and morphological characteristics of the VOPcPhO:P3HT composite films have been studied by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The multidimensional VOPcPhO:P3HT micro-structures formed by electro-spraying with nano-porous surface morphology are very promising for the humidity sensors due to the pore sizes in the range of micro to nano-meters scale. The performance of the VOPcPhO:P3HT electro-sprayed sensor is superior in term of sensitivity, hysteresis and response/recovery times as compared to the spin-coated one. The electro-sprayed humidity sensor exhibits ∼3 times and 0.19 times lower hysteresis in capacitive and resistive mode, respectively, as compared to the spin-coated humidity sensor.

  3. Micro-machined thin film hydrogen gas sensor, and method of making and using the same

    NASA Technical Reports Server (NTRS)

    DiMeo, Jr., Frank (Inventor); Bhandari, Gautam (Inventor)

    2001-01-01

    A hydrogen sensor including a thin film sensor element formed, e.g., by metalorganic chemical vapor deposition (MOCVD) or physical vapor deposition (PVD), on a microhotplate structure. The thin film sensor element includes a film of a hydrogen-interactive metal film that reversibly interacts with hydrogen to provide a correspondingly altered response characteristic, such as optical transmissivity, electrical conductance, electrical resistance, electrical capacitance, magnetoresistance, photoconductivity, etc., relative to the response characteristic of the film in the absence of hydrogen. The hydrogen-interactive metal film may be overcoated with a thin film hydrogen-permeable barrier layer to protect the hydrogen-interactive film from deleterious interaction with non-hydrogen species. The hydrogen sensor of the invention may be usefully employed for the detection of hydrogen in an environment susceptible to the incursion or generation of hydrogen and may be conveniently configured as a hand-held apparatus.

  4. Metrology and characterization of impurity transport during cleaning of micro and nano structures

    NASA Astrophysics Data System (ADS)

    Yan, Jun

    A major challenge in the manufacturing of micro and nano devices is the cleaning, rinsing, and drying of very small structures. Without a technology for in situ and real-time monitoring and controlling, the rinse processes that account for a significant fraction of the total processing steps use a large amount of water and energy perhaps unnecessarily. This "blind" processing approach leads to waste that can have significant economic and environmental impacts. An electrochemical residue sensor (ECRS) has been developed and is aimed at in situ and real-time measurement of residual contamination inside the micro and nano structures. Using this technology, the mechanisms and bottlenecks of cleaning, rinsing, and drying can be investigated and the processes can be monitored and controlled. An equivalent circuit model was developed to assist the design of the sensor; its validity was proved by the first prototype. The simulation results and the experimental data predicted a good sensitivity in a wide range of operational frequency. To use the sensor in a practical rinse tank setup, the sensor-on-wafer prototype was designed and fabricated. Both the fab-scale and the lab-scale tests were performed and results illustrated many successes. The sensor is the first and the only available technology that provides the in situ and real-time cleanness information in the microstructures during the rinse processes. The sensor results distinguished four different types of rinse processes and showed high sensitivity to the ionic concentration change in the microstructures. The impacts of cleaning and rinsing parameters such as flow rate, temperature, cleaning solution concentrations, and process time on the sulfuric acid rinsing efficiency were investigated by using the sensor. The investigation discovered that sulfuric acid rinsing is a two-stage process: a flow-control stage and a desorption-control stage. A comprehensive rinse model was developed to correlate the transport process

  5. The effects of embedded piezoelectric fiber composite sensors on the structural integrity of glass-fiber-epoxy composite laminate

    NASA Astrophysics Data System (ADS)

    Konka, Hari P.; Wahab, M. A.; Lian, K.

    2012-01-01

    Piezoelectric fiber composite sensors (PFCSs) made from micro-sized lead zirconate titanate (PZT) fibers have many advantages over the traditional bulk PZT sensors for embedded sensor applications. PFCSs as embedded sensors will be an ideal choice to continuously monitor the stress/strain levels and health conditions of composite structures. PFCSs are highly flexible, easily embeddable, have high compatibility with composite structures, and also provides manufacturing flexibility. This research is focused on examining the effects of embedding PFCS sensors (macro-fiber composite (MFC) and piezoelectric fiber composite (PFC)) on the structural integrity of glass-fiber-epoxy composite laminates. The strengths of composite materials with embedded PFCSs and conventional PZT sensors were compared, and the advantages of PFCS sensors over PZTs were demonstrated. Initially a numerical simulation study is performed to understand the local stress/strain field near the embedded sensor region inside a composite specimen. High stress concentration regions were observed near the embedded sensor corner edge. Using PFCS leads to a reduction of 56% in longitudinal stress concentration and 38% in transverse stress concentration, when compared to using the conventional PZTs as embedded sensors. In-plane tensile, in-plane tension-tension fatigue, and short beam strength tests are performed to evaluate the strengths/behavior of the composite specimens containing embedded PFCS. From the tensile test it is observed that embedding PFCS and PZT sensors in the composite structures leads to a reduction in ultimate strength by 3 and 6% respectively. From the fatigue test results it is concluded that both embedded PFCS and PZT sensors do not have a significant effect on the fatigue behavior of the composite specimens. From the short beam strength test it is found that embedding PFCS and PZT sensors leads to a reduction in shear strength by 7 and 15% respectively. Overall the pure PZT sensors

  6. Distributed adaptive diagnosis of sensor faults using structural response data

    NASA Astrophysics Data System (ADS)

    Dragos, Kosmas; Smarsly, Kay

    2016-10-01

    The reliability and consistency of wireless structural health monitoring (SHM) systems can be compromised by sensor faults, leading to miscalibrations, corrupted data, or even data loss. Several research approaches towards fault diagnosis, referred to as ‘analytical redundancy’, have been proposed that analyze the correlations between different sensor outputs. In wireless SHM, most analytical redundancy approaches require centralized data storage on a server for data analysis, while other approaches exploit the on-board computing capabilities of wireless sensor nodes, analyzing the raw sensor data directly on board. However, using raw sensor data poses an operational constraint due to the limited power resources of wireless sensor nodes. In this paper, a new distributed autonomous approach towards sensor fault diagnosis based on processed structural response data is presented. The inherent correlations among Fourier amplitudes of acceleration response data, at peaks corresponding to the eigenfrequencies of the structure, are used for diagnosis of abnormal sensor outputs at a given structural condition. Representing an entirely data-driven analytical redundancy approach that does not require any a priori knowledge of the monitored structure or of the SHM system, artificial neural networks (ANN) are embedded into the sensor nodes enabling cooperative fault diagnosis in a fully decentralized manner. The distributed analytical redundancy approach is implemented into a wireless SHM system and validated in laboratory experiments, demonstrating the ability of wireless sensor nodes to self-diagnose sensor faults accurately and efficiently with minimal data traffic. Besides enabling distributed autonomous fault diagnosis, the embedded ANNs are able to adapt to the actual condition of the structure, thus ensuring accurate and efficient fault diagnosis even in case of structural changes.

  7. Software structure for broadband wireless sensor network system

    NASA Astrophysics Data System (ADS)

    Kwon, Hyeokjun; Oh, Sechang; Yoon, Hargsoon; Varadan, Vijay K.

    2010-04-01

    Zigbee Sensor Network system has been investigating for monitoring and analyzing the data measured from a lot of sensors because the Zigbee Sensor Network has several advantages of low power consumption, compact size, and multi-node connection. However, it has a disadvantage not to be able to monitor the data measured from sensors at the remote area such as other room that is located at other city. This paper describes the software structure to compensate the defect with combining the Zigbee Sensor Network and wireless LAN technology for remote monitoring of measured sensor data. The software structure has both benefits of Zigbee Sensor Network and the advantage of wireless LAN. The software structure has three main software structures. The first software structure consists of the function in order to acquire the data from sensors and the second software structure is to gather the sensor data through wireless Zigbee and to send the data to Monitoring system by using wireless LAN. The second part consists of Linux packages software based on 2440 CPU (Samsung corp.), which has ARM9 core. The Linux packages include bootloader, device drivers, kernel, and applications, and the applications are TCP/IP server program, the program interfacing with Zigbee RF module, and wireless LAN program. The last part of software structure is to receive the sensor data through TCP/IP client program from Wireless Gate Unit and to display graphically measured data by using MATLAB program; the sensor data is measured on 100Hz sampling rate and the measured data has 10bit data resolution. The wireless data transmission rate per each channel is 1.6kbps.

  8. Porous Si structure as moisture sensor

    SciTech Connect

    Peterson, D.W.; Nguyen, L.T.

    1996-12-31

    Development and characterization of a capacitive moisture sensor made from porous Si is presented. The sensor development was in support of the DoD funded Plastic Package Availability program and was intended for the detection of pinholes and defects in moisture barrier coatings applied to ICs during fabrication or during the plastic encapsulation assembly process.

  9. Simultaneous measurement of refractive index and temperature with micro silica sphere cavity hybrid Fabry Perot optical fiber sensor

    NASA Astrophysics Data System (ADS)

    Ranjbar Naeini, O. R.; Latifi, H.; Zibaii, M. I.

    2015-09-01

    In this article, a novel Micro Silica Sphere Cavity Hybrid Fabry Perot optical fiber sensor is reported where refractive index (RI) and temperature can be simultaneously measured. The sensor is based on Micro Silica Sphere that was fabricated using a capillary tube. The micro silica sphere and optical fiber form a Hybrid Fabry Perot cavity. The temperature cross sensitivity of this sensor is small enough to be used for accurate RI measurement. The temperature sensitivity and RI sensitivity are -0.0028 dBm/ºC, -0.0044 dBm/ºC , -24.09 dBm/RIU and -20.6 dBm/RIU respectively, using two selected resonances.

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

    PubMed

    Sladitschek, Hanna L; Neveu, Pierre A

    2016-01-01

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

  11. Structure Sensor for mobile markerless augmented reality

    NASA Astrophysics Data System (ADS)

    Kilgus, T.; Bux, R.; Franz, A. M.; Johnen, W.; Heim, E.; Fangerau, M.; Müller, M.; Yen, K.; Maier-Hein, L.

    2016-03-01

    3D Visualization of anatomical data is an integral part of diagnostics and treatment in many medical disciplines, such as radiology, surgery and forensic medicine. To enable intuitive interaction with the data, we recently proposed a new concept for on-patient visualization of medical data which involves rendering of subsurface structures on a mobile display that can be moved along the human body. The data fusion is achieved with a range imaging device attached to the display. The range data is used to register static 3D medical imaging data with the patient body based on a surface matching algorithm. However, our previous prototype was based on the Microsoft Kinect camera and thus required a cable connection to acquire color and depth data. The contribution of this paper is two-fold. Firstly, we replace the Kinect with the Structure Sensor - a novel cable-free range imaging device - to improve handling and user experience and show that the resulting accuracy (target registration error: 4.8+/-1.5 mm) is comparable to that achieved with the Kinect. Secondly, a new approach to visualizing complex 3D anatomy based on this device, as well as 3D printed models of anatomical surfaces, is presented. We demonstrate that our concept can be applied to in vivo data and to a 3D printed skull of a forensic case. Our new device is the next step towards clinical integration and shows that the concept cannot only be applied during autopsy but also for presentation of forensic data to laypeople in court or medical education.

  12. An Efficient Micro Control Unit with a Reconfigurable Filter Design for Wireless Body Sensor Networks (WBSNs)

    PubMed Central

    Chen, Chiung-An; Chen, Shih-Lun; Huang, Hong-Yi; Luo, Ching-Hsing

    2012-01-01

    In this paper, a low-cost, low-power and high performance micro control unit (MCU) core is proposed for wireless body sensor networks (WBSNs). It consists of an asynchronous interface, a register bank, a reconfigurable filter, a slop-feature forecast, a lossless data encoder, an error correct coding (ECC) encoder, a UART interface, a power management (PWM), and a multi-sensor controller. To improve the system performance and expansion abilities, the asynchronous interface is added for handling signal exchanges between different clock domains. To eliminate the noise of various bio-signals, the reconfigurable filter is created to provide the functions of average, binomial and sharpen filters. The slop-feature forecast and the lossless data encoder is proposed to reduce the data of various biomedical signals for transmission. Furthermore, the ECC encoder is added to improve the reliability for the wireless transmission and the UART interface is employed the proposed design to be compatible with wireless devices. For long-term healthcare monitoring application, a power management technique is developed for reducing the power consumption of the WBSN system. In addition, the proposed design can be operated with four different bio-sensors simultaneously. The proposed design was successfully tested with a FPGA verification board. The VLSI architecture of this work contains 7.67-K gate counts and consumes the power of 5.8 mW or 1.9 mW at 100 MHz or 133 MHz processing rate using a TSMC 0.18 μm or 0.13 μm CMOS process. Compared with previous techniques, this design achieves higher performance, more functions, more flexibility and higher compatibility than other micro controller designs. PMID:23443375

  13. An efficient micro control unit with a reconfigurable filter design for wireless body sensor networks (WBSNs).

    PubMed

    Chen, Chiung-An; Chen, Shih-Lun; Huang, Hong-Yi; Luo, Ching-Hsing

    2012-11-22

    In this paper, a low-cost, low-power and high performance micro control unit (MCU) core is proposed for wireless body sensor networks (WBSNs). It consists of an asynchronous interface, a register bank, a reconfigurable filter, a slop-feature forecast, a lossless data encoder, an error correct coding (ECC) encoder, a UART interface, a power management (PWM), and a multi-sensor controller. To improve the system performance and expansion abilities, the asynchronous interface is added for handling signal exchanges between different clock domains. To eliminate the noise of various bio-signals, the reconfigurable filter is created to provide the functions of average, binomial and sharpen filters. The slop-feature forecast and the lossless data encoder is proposed to reduce the data of various biomedical signals for transmission. Furthermore, the ECC encoder is added to improve the reliability for the wireless transmission and the UART interface is employed the proposed design to be compatible with wireless devices. For long-term healthcare monitoring application, a power management technique is developed for reducing the power consumption of the WBSN system. In addition, the proposed design can be operated with four different bio-sensors simultaneously. The proposed design was successfully tested with a FPGA verification board. The VLSI architecture of this work contains 7.67-K gate counts and consumes the power of 5.8 mW or 1.9 mW at 100 MHz or 133 MHz processing rate using a TSMC 0.18 μm or 0.13 μm CMOS process. Compared with previous techniques, this design achieves higher performance, more functions, more flexibility and higher compatibility than other micro controller designs.

  14. Micro-structured surfaces for algal biofilm growth

    NASA Astrophysics Data System (ADS)

    Sathananthan, Suthamathy; Genin, Scott N.; Aitchison, J. Stewart; Allen, D. Grant

    2013-12-01

    It is well known that cells respond to structured surface cues that are on the micro/nanometer scale. Tissue engineering and bio-fouling fields have utilized the semiconductor device fabrication processes to make micro- and nanometer patterned surfaces to study animal cell tissue formation and to prevent algae attachment on marine surfaces respectively. In this paper we describe the use of micro-structured surfaces to study the attachment and growth of algal films. This paper gives an overview of how micro-structured surfaces are made for this purpose, how they are incorporated into a photo bioreactor and how this patterning influences the growth of an algal biofilm. Our results suggest that surface patterning with deeper V-groove patterns that are of the same size scale as the algal species has resulted in higher biomass productivity giving them a chance to embed and attach on the slope and flat surfaces whereas shallower size grooves and completely flat surfaces did not show this trend.

  15. A Fully Integrated and Miniaturized Heavy-metal-detection Sensor Based on Micro-patterned Reduced Graphene Oxide

    NASA Astrophysics Data System (ADS)

    Xuan, Xing; Hossain, Md. Faruk; Park, Jae Yeong

    2016-09-01

    For this paper, a fully integrated and highly miniaturized electrochemical sensor was designed and fabricated on a silicon substrate. A solvothermal-assisted reduced graphene oxide named “TRGO” was then successfully micro-patterned using a lithography technique, followed by the electrodeposition of bismuth (Bi) on the surface of the micro-patterned TRGO for the electrochemical detection of heavy metal ions. The fully integrated electrochemical micro-sensor was then measured and evaluated for the detection of cadmium and lead-heavy metal ions in an acetic-acid buffered solution using the square wave anodic stripping voltammetry (SWASV) technique. The fabricated micro-sensor exhibited a linear detection range of 1.0 μg L‑1 to 120.0 μg L‑1 for both of the metal ions, and detection limits of 0.4 μg L‑1 and 1.0 μg L‑1 were recorded for the lead and cadmium (S/N = 3), respectively. Drinking-water samples were used for the practical assessment of the fabricated micro-sensor, and it showed an acceptable detection performance regarding the metal ions.

  16. A Fully Integrated and Miniaturized Heavy-metal-detection Sensor Based on Micro-patterned Reduced Graphene Oxide.

    PubMed

    Xuan, Xing; Hossain, Md Faruk; Park, Jae Yeong

    2016-09-12

    For this paper, a fully integrated and highly miniaturized electrochemical sensor was designed and fabricated on a silicon substrate. A solvothermal-assisted reduced graphene oxide named "TRGO" was then successfully micro-patterned using a lithography technique, followed by the electrodeposition of bismuth (Bi) on the surface of the micro-patterned TRGO for the electrochemical detection of heavy metal ions. The fully integrated electrochemical micro-sensor was then measured and evaluated for the detection of cadmium and lead-heavy metal ions in an acetic-acid buffered solution using the square wave anodic stripping voltammetry (SWASV) technique. The fabricated micro-sensor exhibited a linear detection range of 1.0 μg L(-1) to 120.0 μg L(-1) for both of the metal ions, and detection limits of 0.4 μg L(-1) and 1.0 μg L(-1) were recorded for the lead and cadmium (S/N = 3), respectively. Drinking-water samples were used for the practical assessment of the fabricated micro-sensor, and it showed an acceptable detection performance regarding the metal ions.

  17. A Fully Integrated and Miniaturized Heavy-metal-detection Sensor Based on Micro-patterned Reduced Graphene Oxide

    PubMed Central

    Xuan, Xing; Hossain, Md. Faruk; Park, Jae Yeong

    2016-01-01

    For this paper, a fully integrated and highly miniaturized electrochemical sensor was designed and fabricated on a silicon substrate. A solvothermal-assisted reduced graphene oxide named “TRGO” was then successfully micro-patterned using a lithography technique, followed by the electrodeposition of bismuth (Bi) on the surface of the micro-patterned TRGO for the electrochemical detection of heavy metal ions. The fully integrated electrochemical micro-sensor was then measured and evaluated for the detection of cadmium and lead-heavy metal ions in an acetic-acid buffered solution using the square wave anodic stripping voltammetry (SWASV) technique. The fabricated micro-sensor exhibited a linear detection range of 1.0 μg L−1 to 120.0 μg L−1 for both of the metal ions, and detection limits of 0.4 μg L−1 and 1.0 μg L−1 were recorded for the lead and cadmium (S/N = 3), respectively. Drinking-water samples were used for the practical assessment of the fabricated micro-sensor, and it showed an acceptable detection performance regarding the metal ions. PMID:27616629

  18. Micro/Nano gas sensors: a new strategy towards in-situ wafer-level fabrication of high-performance gas sensing chips.

    PubMed

    Xu, Lei; Dai, Zhengfei; Duan, Guotao; Guo, Lianfeng; Wang, Yi; Zhou, Hong; Liu, Yanxiang; Cai, Weiping; Wang, Yuelin; Li, Tie

    2015-05-22

    Nano-structured gas sensing materials, in particular nanoparticles, nanotubes, and nanowires, enable high sensitivity at a ppb level for gas sensors. For practical applications, it is highly desirable to be able to manufacture such gas sensors in batch and at low cost. We present here a strategy of in-situ wafer-level fabrication of the high-performance micro/nano gas sensing chips by naturally integrating microhotplatform (MHP) with nanopore array (NPA). By introducing colloidal crystal template, a wafer-level ordered homogenous SnO2 NPA is synthesized in-situ on a 4-inch MHP wafer, able to produce thousands of gas sensing units in one batch. The integration of micromachining process and nanofabrication process endues micro/nano gas sensing chips at low cost, high throughput, and with high sensitivity (down to ~20 ppb), fast response time (down to ~1 s), and low power consumption (down to ~30 mW). The proposed strategy of integrating MHP with NPA represents a versatile approach for in-situ wafer-level fabrication of high-performance micro/nano gas sensors for real industrial applications.

  19. MicroRNA Biomarkers in Neurodegenerative Diseases and Emerging NanoSensors Technology

    PubMed Central

    Shah, Pratik; Cho, Seok Keun; Thulstrup, Peter Waaben; Bjerrum, Morten Jannik; Lee, Phil Hyu; Kang, Ju-Hee; Bhang, Yong-Joo; Yang, Seong Wook

    2017-01-01

    MicroRNAs (miRNAs) are essential small RNA molecules (20–24 nt) that negatively regulate the expression of target genes at the post-transcriptional level. Due to their roles in a variety of biological processes, the aberrant expression profiles of miRNAs have been identified as biomarkers for many diseases, such as cancer, diabetes, cardiovascular disease and neurodegenerative diseases. In order to precisely, rapidly and economically monitor the expression of miRNAs, many cutting-edge nanotechnologies have been developed. One of the nanotechnologies, based on DNA encapsulated silver nanoclusters (DNA/AgNCs), has increasingly been adopted to create nanoscale bio-sensing systems due to its attractive optical properties, such as brightness, tuneable emission wavelengths and photostability. Using the DNA/AgNCs sensor methods, the presence of miRNAs can be detected simply by monitoring the fluorescence alteration of DNA/AgNCs sensors. We introduce these DNA/ AgNCs sensor methods and discuss their possible applications for detecting miRNA biomarkers in neurodegenerative diseases. PMID:28122423

  20. Analytical modelling of a refractive index sensor based on an intrinsic micro Fabry-Perot interferometer.

    PubMed

    Vargas-Rodriguez, Everardo; Guzman-Chavez, Ana D; Cano-Contreras, Martin; Gallegos-Arellano, Eloisa; Jauregui-Vazquez, Daniel; Hernández-García, Juan C; Estudillo-Ayala, Julian M; Rojas-Laguna, Roberto

    2015-10-15

    In this work a refractive index sensor based on a combination of the non-dispersive sensing (NDS) and the Tunable Laser Spectroscopy (TLS) principles is presented. Here, in order to have one reference and one measurement channel a single-beam dual-path configuration is used for implementing the NDS principle. These channels are monitored with a couple of identical optical detectors which are correlated to calculate the overall sensor response, called here the depth of modulation. It is shown that this is useful to minimize drifting errors due to source power variations. Furthermore, a comprehensive analysis of a refractive index sensing setup, based on an intrinsic micro Fabry-Perot Interferometer (FPI) is described. Here, the changes over the FPI pattern as the exit refractive index is varied are analytically modelled by using the characteristic matrix method. Additionally, our simulated results are supported by experimental measurements which are also provided. Finally it is shown that by using this principle a simple refractive index sensor with a resolution in the order of 2.15 × 10(-4) RIU can be implemented by using a couple of standard and low cost photodetectors.

  1. MicroRNA Biomarkers in Neurodegenerative Diseases and Emerging Nano-Sensors Technology.

    PubMed

    Shah, Pratik; Cho, Seok Keun; Thulstrup, Peter Waaben; Bjerrum, Morten Jannik; Lee, Phil Hyu; Kang, Ju-Hee; Bhang, Yong-Joo; Yang, Seong Wook

    2017-01-01

    MicroRNAs (miRNAs) are essential small RNA molecules (20-24 nt) that negatively regulate the expression of target genes at the post-transcriptional level. Due to their roles in a variety of biological processes, the aberrant expression profiles of miRNAs have been identified as biomarkers for many diseases, such as cancer, diabetes, cardiovascular disease and neurodegenerative diseases. In order to precisely, rapidly and economically monitor the expression of miRNAs, many cutting-edge nanotechnologies have been developed. One of the nanotechnologies, based on DNA encapsulated silver nanoclusters (DNA/AgNCs), has increasingly been adopted to create nanoscale bio-sensing systems due to its attractive optical properties, such as brightness, tuneable emission wavelengths and photostability. Using the DNA/AgNCs sensor methods, the presence of miRNAs can be detected simply by monitoring the fluorescence alteration of DNA/AgNCs sensors. We introduce these DNA/ AgNCs sensor methods and discuss their possible applications for detecting miRNA biomarkers in neurodegenerative diseases.

  2. Laser-induced damage threshold of camera sensors and micro-opto-electro-mechanical systems

    NASA Astrophysics Data System (ADS)

    Schwarz, Bastian; Ritt, Gunnar; Körber, Michael; Eberle, Bernd

    2016-10-01

    The continuous development of laser systems towards more compact and efficient devices constitutes an increasing threat to electro-optical imaging sensors such as complementary metal-oxide-semiconductors (CMOS) and charge-coupled devices (CCD). These types of electronic sensors are used in day-to-day life but also in military or civil security applications. In camera systems dedicated to specific tasks, also micro-opto-electro-mechanical systems (MOEMS) like a digital micromirror device (DMD) are part of the optical setup. In such systems, the DMD can be located at an intermediate focal plane of the optics and it is also susceptible to laser damage. The goal of our work is to enhance the knowledge of damaging effects on such devices exposed to laser light. The experimental setup for the investigation of laser-induced damage is described in detail. As laser sources both pulsed lasers and continuous-wave (CW) lasers are used. The laser-induced damage threshold (LIDT) is determined by the single-shot method by increasing the pulse energy from pulse to pulse or in the case of CW-lasers, by increasing the laser power. Furthermore, we investigate the morphology of laser-induced damage patterns and the dependence of the number of destructed device elements on the laser pulse energy or laser power. In addition to the destruction of single pixels, we observe aftereffects like persisting dead columns or rows of pixels in the sensor image.

  3. Analytical Modelling of a Refractive Index Sensor Based on an Intrinsic Micro Fabry-Perot Interferometer

    PubMed Central

    Vargas-Rodriguez, Everardo; Guzman-Chavez, Ana D.; Cano-Contreras, Martin; Gallegos-Arellano, Eloisa; Jauregui-Vazquez, Daniel; Hernández-García, Juan C.; Estudillo-Ayala, Julian M.; Rojas-Laguna, Roberto

    2015-01-01

    In this work a refractive index sensor based on a combination of the non-dispersive sensing (NDS) and the Tunable Laser Spectroscopy (TLS) principles is presented. Here, in order to have one reference and one measurement channel a single-beam dual-path configuration is used for implementing the NDS principle. These channels are monitored with a couple of identical optical detectors which are correlated to calculate the overall sensor response, called here the depth of modulation. It is shown that this is useful to minimize drifting errors due to source power variations. Furthermore, a comprehensive analysis of a refractive index sensing setup, based on an intrinsic micro Fabry-Perot Interferometer (FPI) is described. Here, the changes over the FPI pattern as the exit refractive index is varied are analytically modelled by using the characteristic matrix method. Additionally, our simulated results are supported by experimental measurements which are also provided. Finally it is shown that by using this principle a simple refractive index sensor with a resolution in the order of 2.15 × 10−4 RIU can be implemented by using a couple of standard and low cost photodetectors. PMID:26501277

  4. Design and Analysis of a Single-Camera Omnistereo Sensor for Quadrotor Micro Aerial Vehicles (MAVs).

    PubMed

    Jaramillo, Carlos; Valenti, Roberto G; Guo, Ling; Xiao, Jizhong

    2016-02-06

    We describe the design and 3D sensing performance of an omnidirectional stereo (omnistereo) vision system applied to Micro Aerial Vehicles (MAVs). The proposed omnistereo sensor employs a monocular camera that is co-axially aligned with a pair of hyperboloidal mirrors (a vertically-folded catadioptric configuration). We show that this arrangement provides a compact solution for omnidirectional 3D perception while mounted on top of propeller-based MAVs (not capable of large payloads). The theoretical single viewpoint (SVP) constraint helps us derive analytical solutions for the sensor's projective geometry and generate SVP-compliant panoramic images to compute 3D information from stereo correspondences (in a truly synchronous fashion). We perform an extensive analysis on various system characteristics such as its size, catadioptric spatial resolution, field-of-view. In addition, we pose a probabilistic model for the uncertainty estimation of 3D information from triangulation of back-projected rays. We validate the projection error of the design using both synthetic and real-life images against ground-truth data. Qualitatively, we show 3D point clouds (dense and sparse) resulting out of a single image captured from a real-life experiment. We expect the reproducibility of our sensor as its model parameters can be optimized to satisfy other catadioptric-based omnistereo vision under different circumstances.

  5. A suite of optical fibre sensors for structural condition monitoring

    NASA Astrophysics Data System (ADS)

    Sun, T.; Grattan, K. T. V.; Carlton, J.

    2015-05-01

    This paper is to review the research activities at City University London in the development of a range of fibre Bragg grating (FBG)-based sensors, including strain, temperature, relative humidity, vibration and acoustic sensors, with an aim to meet the increasing demands from industry for structural condition monitoring. As a result, arrays of optical fibre sensors have been instrumented into various types of structures, including concrete, limestone, marine propellers, pantograph and electrical motors, allowing for both static and dynamic monitoring and thus enhanced structural reliability and integrity.

  6. Erbium-doped fiber amplifier elements for structural analysis sensors

    NASA Technical Reports Server (NTRS)

    Hanna-Hawver, P.; Kamdar, K. D.; Mehta, S.; Nagarajan, S.; Nasta, M. H.; Claus, R. O.

    1992-01-01

    The use of erbium-doped fiber amplifiers (EDFA's) in optical fiber sensor systems for structural analysis is described. EDFA's were developed for primary applications as periodic regenerator amplifiers in long-distance fiber-based communication systems. Their in-line amplification performance also makes them attractive for optical fiber sensor systems which require long effective lengths or the synthesis of special length-dependent signal processing functions. Sensor geometries incorporating EDFA's in recirculating and multiple loop sensors are discussed. Noise and polarization birefringence are also considered, and the experimental development of system components is discussed.

  7. Sensitive elastic modulus mapping of micro-structured biomaterials

    NASA Astrophysics Data System (ADS)

    Sun, J. Y.; Liu, X.; Tong, J.; Yue, Z. Y.

    2010-08-01

    In nature, insects and plants have evolved ways of living and reproducing themselves using the least amount of resource. This involves both efficiency in metabolism and optimal mechanisms and materials for life functions. Human beings have long tried to learn from and mimic nature. The study of biological materials has received increasing interest in recent years due to the often extraordinary mechanical properties and unusual structures exhibited by these materials. Micro-structure biomaterials exhibit important local variations of elasticity due to the complex and anisotropic composition. In this paper, a specially developed multi-function tribological probe microscope (TPM) has been used to map the mechanical properties of some special micro-structured biomaterials. Results of the mapped surface topography and elastic modulus on specimens of elytra cuticle of dung beetle, nacre of shell and bovine horn have shown some significant lateral variations of elasticity across the surface area.

  8. Fiber Optic Sensors for Smart Materials and Structures

    NASA Technical Reports Server (NTRS)

    Singh, H.; Chang, C. C.; Boyer, T.; Sirkis, J. S.

    1996-01-01

    In this paper we describe recently developed fiber sensors which are capable of monitoring the health of smart-structures. The unobstrusive geometry of these sensors make them an excellent choice for embedding the sensor in composite materials to measure internal states of strain in structures and materials. Some of these sensors have gage lengths that can be tailored from tens of microns to many meters. We will describe various demodulation schemes (Pseudo-Heterodyne, Synthetic-Heterodyne, Homodyne, Differential-Cross Multiplier, and Single Channel Phase-Tracker) to obtain high bandwidth measurements, enabling measurement of static to high frequency impact generated strains with a dynamic response exceeding tens of thousands of microstrains. In addition, we will show that we can tailor the fiber sensor to either measure only strain and reject temperature response or measure only the temperature, or measure both temperature and strain simultaneously. We will also demonstrate the ability to measure multiple strain components inside a host simultaneously using a single fiber sensor embedded in the host using a certain sensor type and transverse strain immunity using another sensor type. Additionally we will show the ability to measure temperature up to 100 C using fiber optic sensors.

  9. Optical fiber sensors and signal processing for intelligent structure monitoring

    NASA Technical Reports Server (NTRS)

    Rogowski, Robert; Claus, R. O.; Lindner, D. K.; Thomas, Daniel; Cox, Dave

    1988-01-01

    The analytic and experimental performance of optical fiber sensors for the control of vibration of large aerospace and other structures are investigated. In particular, model domain optical fiber sensor systems, are being studied due to their apparent potential as distributed, low mass sensors of vibration over appropriate ranges of both low frequency and low amplitude displacements. Progress during the past three months is outlined. Progress since September is divided into work in the areas of experimental hardware development, analytical analysis, control design and sensor development. During the next six months, tests of a prototype closed-loop control system for a beam are planned which will demonstrate the solution of several optical fiber instrumentation device problems, the performance of the control system theory which incorporates the model of the modal domain sensor, and the potential for distributed control which this sensor approach offers.

  10. Army requirements for micro and nanotechnology-based sensors in weapons health and battlefield environmental monitoring applications

    NASA Astrophysics Data System (ADS)

    Ruffin, Paul; Brantley, Christina; Edwards, Eugene; Hutcheson, Guilford

    2006-03-01

    The Army Aviation and Missile Research, Development, and Engineering Center (AMRDEC) and the Army Research Laboratory (ARL) have initiated a joint advanced technology demonstration program entitled "Prognostics/Diagnostics for the Future Force (PDFF)" with a key objective of developing low or no power embedded sensor suites for harsh environmental monitoring. The most critical challenge of the program is to specify requirements for the embedded sensor suites which will perform on-board diagnostics, maintain a history of sensor data, and forecast weapon health. The authors are currently collaborating with the PDFF program managers and potential customers to quantify the requirements for remotely operated, micro/nano-technology-based sensors for a host of candidate weapon systems. After requirements are finalized, current micro/nanotechnology-based temperature, humidity, g-shock, vibration and chemical sensors for monitoring the out-gassing of weapons propellant, as well as hazardous gaseous species on the battlefield and in urban environments will be improved to meet the full requirements of the PDFF program. In this paper, performance requirements such as power consumption, reliability, maintainability, survivability, size, and cost, along with the associated technical challenges for micro/nanotechnology-based sensor systems operating in military environments, are discussed. In addition, laboratory results from the design and testing of a wireless sensor array, which was developed using a thin film of functionalized carbon nanotube materials, are presented. Conclusions from the research indicate that the detection of bio-hazardous materials is possible using passive and active wireless sensors based on monitoring the reflected phase from the sensor.

  11. Embedded Sensor Array Development for Composite Structure Integrity Monitoring

    SciTech Connect

    Kumar, A.; Bryan, W. L.; Clonts, L. G.; Franks, S.

    2007-06-26

    The purpose of this Cooperative Research and Development Agreement (CRADA) between UT-Battelle, LLC (the "Contractor") and Accellent Technologies, Inc. (the "Participant") was for the development of an embedded ultrasonic sensor system for composite structure integrity monitoring.

  12. Effect of annealing on proton irradiated AlGaN/GaN based micro-Hall sensors

    SciTech Connect

    Abderrahmane, A.; Takahashi, H.; Tashiro, T.; Ko, P. J.; Okada, H.; Sandhu, A.; Sato, S.; Ohshima, T.

    2014-02-20

    The effect of annealing at 673 K on irradiated micro-Hall sensors irradiated with protons at 380keV and fluences of 10{sup 14}, 10{sup 15} and 10{sup 16} protons/cm{sup 2} is reported. Cathodoluminescence measurements were carried out at room temperature before and after annealing and showed improvement in the band edge band emission of the GaN layer. After annealing a sensor irradiated by 10{sup 15} protons/cm{sup 2} the device became operational with improvements in its magnetic sensitivity. All irradiated sensors showed improvement in their electrical characteristics after annealing.

  13. Ultrasensitive electrochemical sensor for mercury (II) based on target-induced structure-switching DNA.

    PubMed

    Wu, Danhong; Zhang, Qing; Chu, Xia; Wang, Haibo; Shen, Guoli; Yu, Ruqin

    2010-01-15

    A novel electrochemical sensor has been developed for sensitive and selective detection of mercury (II) based on target-induced structure-switching DNA. A 33-mer oligonucleotide 1 with five self-complementary base pairs separated by seven thymine-thymine mismatches was first immobilized on the electrode via self-assembly of the terminal thiol moiety and then hybridized with a ferrocene-tagged oligonucleotide 2, leading to a high redox current. In the presence of Hg(2+), mercury-mediated base pairs (T-Hg(2+)-T) induced the folding of the oligonucleotide 1 into a hairpin structure, resulting in the release of the ferrocene-tagged oligonucleotide 2 from the electrode surface with a substantially decreased redox current. The response characteristics of the sensor were thoroughly investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The effect of the reaction temperature on the response of the sensor was also studied in detail. The results revealed that the sensor showed sensitive response to Hg(2+) in a concentration range from 0.1 nM to 5 microM with a detection limit of 0.06 nM. In addition, this strategy afforded exquisite selectivity for Hg(2+) against other environmentally related metal ions, which was superior to that of previous anodic stripping voltammetry (ASV)-based techniques. The excellent sensitivity and selectivity signified the potential of the sensor for Hg(2+) detection in real environmental samples.

  14. Nanofibers and thin films as a selective membrane for sensors and microTAS

    NASA Astrophysics Data System (ADS)

    da Silva, A. N. R.; da Silva, M. L. P.; Fachini, E. R.

    2013-03-01

    A composite material of PAN (polyacrylonitrile), starch granules and dimethylformamide as solvent was used as a selective membrane for volatile organic compounds (VOCs) in gaseous phase. This composite was produced as a thin film obtained by spin-casting and as a fiber mat produced by electrospinning. The fiber mat was tested for adsorption of VOCs and water. Characterization used microscopy (electron scanning and optical) in order to evaluate the fiber morphology and the starch incorporation in the PAN matrix. Infrared spectroscopy was intended to determine the starch presence. Relative viscosity of the starch/PAN suspensions was measured in order to provide a model of composite fiber formation. Quartz crystal microbalance experiments determined VOCs and water adsorption. Fibers incorporated the starch granules, making the composite sensible to water; but VOCs were not detected. Therefore, the composite was found to be a good choice as selective barrier on sensors or microTAS protection purposes.

  15. MicroRNA Sensor Based on Magnetic Beads and Enzymatic Probes

    NASA Astrophysics Data System (ADS)

    Zhang, Yue; Zhou, Dejian; He, Junhui

    2014-12-01

    MicroRNAs are associated with multiple cellular processes and diseases. Here, we designed a highly sensitive, magnetically retrievable biosensor using magnetic beads (MBs) as a model RNA sensor. The assay utilized two biotinylated probes, which were hybridized to the complementary target miRNA in a sandwich assay format. One of the biotinylated ends of the hybridization complex was immobilized onto the surface of a NeutrAvidin (NAV) coated MB and the other biotinylated end was conjugated to HRP via NAV-biotin interaction. The results were presented by colorimetric absorbance of the resorufin product from amplex red oxidation. We show that by combining the use of MBs as well as bio-specific immobilization, the sensitivity of miRNA detection is down to 100 pM. This model HRP-MBs system can be used for simple, rapid colorimetric quantification of low level DNA/RNA or other small molecules.

  16. Micro-drilling of polymer tubular ultramicroelectrode arrays for electrochemical sensors.

    PubMed

    Kafka, Jan; Skaarup, Steen; Geschke, Oliver; Larsen, Niels B

    2013-05-14

    We present a reproducible fast prototyping procedure based on micro-drilling to produce homogeneous tubular ultramicroelectrode arrays made from poly(3,4-ethylenedioxythiophene) (PEDOT), a conductive polymer. Arrays of Ø 100 µm tubular electrodes each having a height of 0.37 ± 0.06 µm were reproducibly fabricated. The electrode dimensions were analyzed by SEM after deposition of silver dendrites to visualize the electroactive electrode area. The electrochemical applicability of the electrodes was demonstrated by voltammetric and amperometric detection of ferri-/ferrocyanide. Recorded signals were in agreement with results from finite element modelling of the system. The tubular PEDOT ultramicroelectrode arrays were modified by prussian blue to enable the detection of hydrogen peroxide. A linear sensor response was demonstrated for hydrogen peroxide concentrations from 0.1 mM to 1 mM.

  17. Enhanced Ion Acceleration from Micro-tube Structured Targets

    NASA Astrophysics Data System (ADS)

    Snyder, Joseph; Ji, Liangliang; Akli, Kramer

    2015-11-01

    We present an enhanced ion acceleration method that leverages recent advancements in 3D printing for target fabrication. Using the three-dimensional Particle-in-Cell simulation code Virtual Laser-Plasma Lab (VLPL), we model the interaction of a short pulse, high intensity laser with a micro-tube plasma (MTP) structured target. When compared to flat foils, the MTP target enhances the maximum proton energy by a factor of about 4. The ion enhancement is attributed to two main factors: high energy electrons extracted from the tube structure enhancing the accelerating field and light intensification within the MTP target increasing the laser intensity at the location of the foil. We also present results on ion energy scaling with micro-tube diameter and incident laser pulse intensity. This work was supported by the AFOSR under contract No. FA9550-14-1-0085.

  18. Sensitivity and noise of micro-Hall magnetic sensors based on InGaAs quantum wells

    NASA Astrophysics Data System (ADS)

    Chenaud, B.; Segovia-Mera, A.; Delgard, A.; Feltin, N.; Hoffmann, A.; Pascal, F.; Zawadzki, W.; Mailly, D.; Chaubet, C.

    2016-01-01

    We study the room-temperature performance of micro-Hall magnetic sensors based on pseudomorphic InGaAs quantum wells. Active areas of our sensors range from 1 to 80 μm. We focus on the smallest detectable magnetic fields in small sensors and perform a systematic study of noise at room temperature in the frequency range between 1 Hz and 100 kHz. Our data are interpreted by the mobility fluctuation model. The Hooge parameter is determined for the applied technology. We show that, independently of the experimental frequency, the ratio of sensitivity to noise is proportional to characteristic length of the sensor. The resolution of 1 mG/√{Hz } is achievable in a 3 μm sensor at room temperature.

  19. Structural coloration of metallic surfaces with micro/nano-structures induced by elliptical vibration texturing

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Pan, Yayue; Guo, Ping

    2017-04-01

    Creating orderly periodic micro/nano-structures on metallic surfaces, or structural coloration, for control of surface apparent color and optical reflectivity has been an exciting research topic over the years. The direct applications of structural coloration include color marking, display devices, and invisibility cloak. This paper presents an efficient method to colorize metallic surfaces with periodic micro/nano-gratings using elliptical vibration texturing. When the tool vibration is coupled with a constant cutting velocity, controlled periodic ripples can be generated due to the overlapping tool trajectory. These periodic ripples with a wavelength near visible spectrum can act as micro-gratings to introduce iridescent colors. The proposed technique also provides a flexible method for color marking of metallic surfaces with arbitrary patterns and images by precise control of the spacing distance and orientation of induced micro/nano-ripples. Theoretical analysis and experimental results are given to demonstrate structural coloration of metals by a direct mechanical machining technique.

  20. Micro-displacement sensor based on a hollow-core photonic crystal fiber.

    PubMed

    Rodrigues Pinto, Ana Margarida; Baptista, José Manuel; Santos, José Luís; Lopez-Amo, Manuel; Frazão, Orlando

    2012-12-17

    A sensing head based on a hollow-core photonic crystal fiber for in-reflection measurement of micro-displacements is presented. The sensing structure takes advantage of the multimodal behavior of a short segment of hollow-core photonic crystal fiber in-reflection, being spliced to a single mode fiber at its other end. A modal interferometer is obtained when the sensing head is close to a mirror, through which displacement is measured.

  1. Micro-Displacement Sensor Based on a Hollow-Core Photonic Crystal Fiber

    PubMed Central

    Pinto, Ana Margarida Rodrigues; Baptista, José Manuel; Santos, José Luís; Lopez-Amo, Manuel; Frazão, Orlando

    2012-01-01

    A sensing head based on a hollow-core photonic crystal fiber for in-reflection measurement of micro-displacements is presented. The sensing structure takes advantage of the multimodal behavior of a short segment of hollow-core photonic crystal fiber in-reflection, being spliced to a single mode fiber at its other end. A modal interferometer is obtained when the sensing head is close to a mirror, through which displacement is measured. PMID:23247414

  2. Mechatronic Scanning System with Integrated Micro Electro Mechanical System Position Sensors

    NASA Astrophysics Data System (ADS)

    Stavrov, Vladimir; Chakarov, Dimitar; Shulev, Assen; Tsveov, Mihail

    2016-06-01

    In this paper, a study of a mechatronic scanning system for application in the microbiology, microelectronics research, chemistry, etc. is presented. Integrated silicon micro electro mechanical system (MEMS) position sensor is used for monitoring the displacement of the scanning system. The utilized silicon MEMS sensors with sidewall embedded piezoresistors possess a number of key advantages such as high sensitivity, low noise and extremely low temperature dependence. Design of 2D scanning system with a travel range of 22 × 22 μm2 has been presented in present work. This system includes a Compliant Transmission Mechanism, (CTM) designed as a complex elastic mechanism, comprising four parallelograms. Computer aided desigh (CAD) model and finite element analysis (FEA) of the Compliant Transmission Mechanism mechanisms have been carried out. A prototype of the scanning system is fabricated, based on CAD model. An experimental set-up of an optical system and a correlation technique for digital image processing have been used for testing the scanning system prototype. Results of the experimental investigations of the prototyped scanning system are also presented.

  3. Carbon nanotube thin film strain sensor models assembled using nano- and micro-scale imaging

    NASA Astrophysics Data System (ADS)

    Lee, Bo Mi; Loh, Kenneth J.; Yang, Yuan-Sen

    2017-02-01

    Nanomaterial-based thin films, particularly those based on carbon nanotubes (CNT), have brought forth tremendous opportunities for designing next-generation strain sensors. However, their strain sensing properties can vary depending on fabrication method, post-processing treatment, and types of CNTs and polymers employed. The objective of this study was to derive a CNT-based thin film strain sensor model using inputs from nano-/micro-scale experimental measurements of nanotube physical properties. This study began with fabricating ultra-low-concentration CNT-polymer thin films, followed by imaging them using atomic force microscopy. Image processing was employed for characterizing CNT dispersed shapes, lengths, and other physical attributes, and results were used for building five different types of thin film percolation-based models. Numerical simulations were conducted to assess how the morphology of dispersed CNTs in its 2D matrix affected bulk film electrical and electromechanical (strain sensing) properties. The simulation results showed that CNT morphology had a significant impact on strain sensing performance.

  4. A novel micro- and nano-scale positioning sensor based on radio frequency resonant cavities.

    PubMed

    Asua, Estibaliz; Etxebarria, Victor; García-Arribas, Alfredo; Feutchwanger, Jorge; Portilla, Joaquín; Lucas, Julio

    2014-05-30

    In many micro- and nano-scale technological applications high sensitivity displacement sensors are needed, especially in ultraprecision metrology and manufacturing. In this work a new way of sensing displacement based on radio frequency resonant cavities is presented and experimentally demonstrated using a first laboratory prototype. The principle of operation of the new transducer is summarized and tested. Furthermore, an electronic interface that can be used together with the displacement transducer is designed and proved. It has been experimentally demonstrated that very high and linear sensitivity characteristic curves, in the range of some kHz/nm; are easily obtainable using this kind of transducer when it is combined with a laboratory network analyzer. In order to replace a network analyzer and provide a more affordable, self-contained, compact solution, an electronic interface has been designed, preserving as much as possible the excellent performance of the transducer, and turning it into a true standalone positioning sensor. The results obtained using the transducer together with a first prototype of the electronic interface built with cheap discrete elements show that positioning accuracies in the micrometer range are obtainable using this cost-effective solution. Better accuracies would also be attainable but using more involved and costly electronics interfaces.

  5. A Novel Micro- and Nano-Scale Positioning Sensor Based on Radio Frequency Resonant Cavities

    PubMed Central

    Asua, Estibaliz; Etxebarria, Victor; García-Arribas, Alfredo; Feutchwanger, Jorge; Portilla, Joaquín; Lucas, Julio

    2014-01-01

    In many micro- and nano-scale technological applications high sensitivity displacement sensors are needed, especially in ultraprecision metrology and manufacturing. In this work a new way of sensing displacement based on radio frequency resonant cavities is presented and experimentally demonstrated using a first laboratory prototype. The principle of operation of the new transducer is summarized and tested. Furthermore, an electronic interface that can be used together with the displacement transducer is designed and proved. It has been experimentally demonstrated that very high and linear sensitivity characteristic curves, in the range of some kHz/nm; are easily obtainable using this kind of transducer when it is combined with a laboratory network analyzer. In order to replace a network analyzer and provide a more affordable, self-contained, compact solution, an electronic interface has been designed, preserving as much as possible the excellent performance of the transducer, and turning it into a true standalone positioning sensor. The results obtained using the transducer together with a first prototype of the electronic interface built with cheap discrete elements show that positioning accuracies in the micrometer range are obtainable using this cost-effective solution. Better accuracies would also be attainable but using more involved and costly electronics interfaces. PMID:24887041

  6. The Transition-Edge-Sensor Array for the Micro-X Sounding Rocket

    NASA Technical Reports Server (NTRS)

    Eckart, M. E.; Adams, J. S.; Bailey, C. N.; Bandler, S. R.; Busch, Sarah Elizabeth; Chervenak J. A.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Porst, J. P.; Porter, F. S.; Sadleir, J. E.; Smith, Stephen J.; Figueroa-Feliciano, Enectali

    2012-01-01

    The Micro-X sounding rocket program will fly a 128-element array of transition-edge-sensor microcalorimeters to enable high-resolution X-ray imaging spectroscopy of the Puppis-A supernova remnant. To match the angular resolution of the optics while maximizing the field-of-view and retaining a high energy resolution (< 4 eV at 1 keV), we have designed the pixels using 600 x 600 sq. micron Au/Bi absorbers, which overhang 140 x 140 sq. micron Mo/Au sensors. The data-rate capabilities of the rocket telemetry system require the pulse decay to be approximately 2 ms to allow a significant portion of the data to be telemetered during flight. Here we report experimental results from the flight array, including measurements of energy resolution, uniformity, and absorber thermalization. In addition, we present studies of test devices that have a variety of absorber contact geometries, as well as a variety of membrane-perforation schemes designed to slow the pulse decay time to match the telemetry requirements. Finally, we describe the reduction in pixel-to-pixel crosstalk afforded by an angle-evaporated Cu backside heatsinking layer, which provides Cu coverage on the four sidewalls of the silicon wells beneath each pixel.

  7. A wireless laser displacement sensor node for structural health monitoring.

    PubMed

    Park, Hyo Seon; Kim, Jong Moon; Choi, Se Woon; Kim, Yousok

    2013-09-30

    This study describes a wireless laser displacement sensor node that measures displacement as a representative damage index for structural health monitoring (SHM). The proposed measurement system consists of a laser displacement sensor (LDS) and a customized wireless sensor node. Wireless communication is enabled by a sensor node that consists of a sensor module, a code division multiple access (CDMA) communication module, a processor, and a power module. An LDS with a long measurement distance is chosen to increase field applicability. For a wireless sensor node driven by a battery, we use a power control module with a low-power processor, which facilitates switching between the sleep and active modes, thus maximizing the power consumption efficiency during non-measurement and non-transfer periods. The CDMA mode is also used to overcome the limitation of communication distance, which is a challenge for wireless sensor networks and wireless communication. To evaluate the reliability and field applicability of the proposed wireless displacement measurement system, the system is tested onsite to obtain the required vertical displacement measurements during the construction of mega-trusses and an edge truss, which are the primary structural members in a large-scale irregular building currently under construction. The measurement values confirm the validity of the proposed wireless displacement measurement system and its potential for use in safety evaluations of structural elements.

  8. A Wireless Laser Displacement Sensor Node for Structural Health Monitoring

    PubMed Central

    Park, Hyo Seon; Kim, Jong Moon; Choi, Se Woon; Kim, Yousok

    2013-01-01

    This study describes a wireless laser displacement sensor node that measures displacement as a representative damage index for structural health monitoring (SHM). The proposed measurement system consists of a laser displacement sensor (LDS) and a customized wireless sensor node. Wireless communication is enabled by a sensor node that consists of a sensor module, a code division multiple access (CDMA) communication module, a processor, and a power module. An LDS with a long measurement distance is chosen to increase field applicability. For a wireless sensor node driven by a battery, we use a power control module with a low-power processor, which facilitates switching between the sleep and active modes, thus maximizing the power consumption efficiency during non-measurement and non-transfer periods. The CDMA mode is also used to overcome the limitation of communication distance, which is a challenge for wireless sensor networks and wireless communication. To evaluate the reliability and field applicability of the proposed wireless displacement measurement system, the system is tested onsite to obtain the required vertical displacement measurements during the construction of mega-trusses and an edge truss, which are the primary structural members in a large-scale irregular building currently under construction. The measurement values confirm the validity of the proposed wireless displacement measurement system and its potential for use in safety evaluations of structural elements. PMID:24084114

  9. Efficient placement of structural dynamics sensors on the space station

    NASA Technical Reports Server (NTRS)

    Lepanto, Janet A.; Shepard, G. Dudley

    1987-01-01

    System identification of the space station dynamic model will require flight data from a finite number of judiciously placed sensors on it. The placement of structural dynamics sensors on the space station is a particularly challenging problem because the station will not be deployed in a single mission. Given that the build-up sequence and the final configuration for the space station are currently undetermined, a procedure for sensor placement was developed using the assembly flights 1 to 7 of the rephased dual keel space station as an example. The procedure presented approaches the problem of placing the sensors from an engineering, as opposed to a mathematical, point of view. In addition to locating a finite number of sensors, the procedure addresses the issues of unobserved structural modes, dominant structural modes, and the trade-offs involved in sensor placement for space station. This procedure for sensor placement will be applied to revised, and potentially more detailed, finite element models of the space station configuration and assembly sequence.

  10. Detection of the superconducting transition and magnetic flux trapping in a niobium micro-ring by using micro-Hall sensors

    NASA Astrophysics Data System (ADS)

    Kahng, Yung Ho; Kim, Yun Won; Kim, Mun Seog; Song, Woon; Choi, Jae-Hyuk; Joo, Sungjung; Hong, Jinki; Rhie, Kungwon; Lee, Soon-Gul

    2016-11-01

    An InAs heterostructure-based micro-Hall sensor was used to study the magnetic properties of a superconducting Nb micro-ring, enabling observation of magnetic phenomena such as diamagnetism onset and magnetic flux trapping in the 20- μm-diameter sample. The superconducting diamagnetism of the micro-ring was observed to develop slowly from T = 7.5 K down to 5 K and showed a notably sharp and substantial drop at 7.0 K, the zero-resistivity temperature obtained from transport measurements on a strip-patterned sample. The observed superconducting transition is discussed in terms of a percolation scenario. In magnetic-field-cooling measurements, the Hall signal from the magnetic flux trapped in the Nb ring at 4.5 K was detected at a sufficiently high level for quantitative comparison with the estimate.

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

    PubMed

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

    2015-11-23

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

  12. Fiber optic sensors for structural health monitoring of air platforms.

    PubMed

    Guo, Honglei; Xiao, Gaozhi; Mrad, Nezih; Yao, Jianping

    2011-01-01

    Aircraft operators are faced with increasing requirements to extend the service life of air platforms beyond their designed life cycles, resulting in heavy maintenance and inspection burdens as well as economic pressure. Structural health monitoring (SHM) based on advanced sensor technology is potentially a cost-effective approach to meet operational requirements, and to reduce maintenance costs. Fiber optic sensor technology is being developed to provide existing and future aircrafts with SHM capability due to its unique superior characteristics. This review paper covers the aerospace SHM requirements and an overview of the fiber optic sensor technologies. In particular, fiber Bragg grating (FBG) sensor technology is evaluated as the most promising tool for load monitoring and damage detection, the two critical SHM aspects of air platforms. At last, recommendations on the implementation and integration of FBG sensors into an SHM system are provided.

  13. Fiber Optic Sensors for Structural Health Monitoring of Air Platforms

    PubMed Central

    Guo, Honglei; Xiao, Gaozhi; Mrad, Nezih; Yao, Jianping

    2011-01-01

    Aircraft operators are faced with increasing requirements to extend the service life of air platforms beyond their designed life cycles, resulting in heavy maintenance and inspection burdens as well as economic pressure. Structural health monitoring (SHM) based on advanced sensor technology is potentially a cost-effective approach to meet operational requirements, and to reduce maintenance costs. Fiber optic sensor technology is being developed to provide existing and future aircrafts with SHM capability due to its unique superior characteristics. This review paper covers the aerospace SHM requirements and an overview of the fiber optic sensor technologies. In particular, fiber Bragg grating (FBG) sensor technology is evaluated as the most promising tool for load monitoring and damage detection, the two critical SHM aspects of air platforms. At last, recommendations on the implementation and integration of FBG sensors into an SHM system are provided. PMID:22163816

  14. Microwave Sensor for Blade Tip Clearance and Structural Health Measurements

    NASA Technical Reports Server (NTRS)

    Woike, Mark R.; Bencic, Timothy J.

    2008-01-01

    The use of microwave based sensors for the health monitoring of rotating machinery is being explored at the NASA Glenn Research Center. The microwave sensor works on the principle of sending a continuous signal towards a rotating component and measuring the reflected signal. The phase shift of the reflected signal is proportional to the distance between the sensor and the component that is being measured. This type of sensor is beneficial in that it has the ability to operate at extremely high temperatures and is unaffected by contaminants that may be present in the rotating machinery. It is intended to use these probes in the hot sections of turbine engines for closed loop turbine clearance control and structural health measurements. Background on the sensors, an overview of their calibration and preliminary results from using them to make blade tip clearance and health measurements on a large axial vane fan will be presented.

  15. Fiber Bragg grating sensors for structural and railway applications

    NASA Astrophysics Data System (ADS)

    Tam, H. Y.; Liu, S. Y.; Guan, B. O.; Chung, W. H.; Chan, T. H.; Cheng, L. K.

    2005-02-01

    Historically, due to the high cost of optical devices, fiber-optics sensor systems were only employed in niche areas where conventional electrical sensors are not suitable. This scenario changed dramatically in the last few years following the explosion of the Internet which caused the rapid expansion of the optical fiber telecommunication industry and substantially driven down the cost of optical components. In recent years, fiber-optic sensors and particularly fiber Bragg grating (FBG) sensors have attracted a lot of interests and are being used in numerous applications. We have conducted several field trials of FBG sensors for railway applications and structural monitoring. About 30 FBG sensors were installed on the rail tracks of Kowloon-Canton Railway Corp. for train identification and speed measurements and the results obtained show that FBG sensors exhibit very good performance and could play a major role in the realization of "Smart Railway". FBG sensors were also installed on Hong Kong's landmark TsingMa Bridge, which is the world longest suspension bridge (2.2 km) that carries both trains and regular road traffic. The trials were carried out with a high-speed (up to 20 kHz) interrogation system based on CCD and also with a interrogation unit that based on scanning optical filter (up to 70 Hz). Forty FBGs sensors were divided into 3 arrays and installed on different parts of the bridge (suspension cable, rocker bearing and truss girders). The objectives of the field trial on the TsingMa Bridge are to monitor the strain of different parts of the bridge under railway load and highway load, and to compare the FBG sensors' performance with conventional resistive strain gauges already installed on the bridge. The measured results show that excellent agreement was obtained between the 2 types of sensors.

  16. Research on micro-sized acoustic bandgap structures.

    SciTech Connect

    Fleming, James Grant; McCormick, Frederick Bossert; Su, Mehmet F.; El-Kady, Ihab Fathy; Olsson, Roy H., III; Tuck, Melanie R.

    2010-01-01

    Phononic crystals (or acoustic crystals) are the acoustic wave analogue of photonic crystals. Here a periodic array of scattering inclusions located in a homogeneous host material forbids certain ranges of acoustic frequencies from existence within the crystal, thus creating what are known as acoustic (or phononic) bandgaps. The vast majority of phononic crystal devices reported prior to this LDRD were constructed by hand assembling scattering inclusions in a lossy viscoelastic medium, predominantly air, water or epoxy, resulting in large structures limited to frequencies below 1 MHz. Under this LDRD, phononic crystals and devices were scaled to very (VHF: 30-300 MHz) and ultra (UHF: 300-3000 MHz) high frequencies utilizing finite difference time domain (FDTD) modeling, microfabrication and micromachining technologies. This LDRD developed key breakthroughs in the areas of micro-phononic crystals including physical origins of phononic crystals, advanced FDTD modeling and design techniques, material considerations, microfabrication processes, characterization methods and device structures. Micro-phononic crystal devices realized in low-loss solid materials were emphasized in this work due to their potential applications in radio frequency communications and acoustic imaging for medical ultrasound and nondestructive testing. The results of the advanced modeling, fabrication and integrated transducer designs were that this LDRD produced the 1st measured phononic crystals and phononic crystal devices (waveguides) operating in the VHF (67 MHz) and UHF (937 MHz) frequency bands and established Sandia as a world leader in the area of micro-phononic crystals.

  17. Wireless Zigbee strain gage sensor system for structural health monitoring

    NASA Astrophysics Data System (ADS)

    Ide, Hiroshi; Abdi, Frank; Miraj, Rashid; Dang, Chau; Takahashi, Tatsuya; Sauer, Bruce

    2009-05-01

    A compact cell phone size radio frequency (ZigBee) wireless strain measurement sensor system to measure the structural strain deformation was developed. The developed system provides an accurate strain measurement data stream to the Internet for further Diagnostic and Prognostic (DPS) correlation. Existing methods of structural measurement by strain sensors (gauges) do not completely satisfy problems posed by continuous structural health monitoring. The need for efficient health monitoring methods with real-time requirements to bidirectional data flow from sensors and to a commanding device is becoming critical for keeping our daily life safety. The use of full-field strain measurement techniques could reduce costly experimental programs through better understanding of material behavior. Wireless sensor-network technology is a monitoring method that is estimated to grow rapidly providing potential for cost savings over traditional wired sensors. The many of currently available wireless monitoring methods have: the proactive and constant data rate character of the data streams rather than traditional reactive, event-driven data delivery; mostly static node placement on structures with limited number of nodes. Alpha STAR Electronics' wireless sensor network system, ASWN, addresses some of these deficiencies, making the system easier to operate. The ASWN strain measurement system utilizes off-the-shelf sensors, namely strain gauges, with an analog-to-digital converter/amplifier and ZigBee radio chips to keep cost lower. Strain data is captured by the sensor, converted to digital form and delivered to the ZigBee radio chip, which in turn broadcasts the information using wireless protocols to a Personal Data Assistant (PDA) or Laptop/Desktop computers. From here, data is forwarded to remote computers for higher-level analysis and feedback using traditional cellular and satellite communication or the Ethernet infrastructure. This system offers a compact size, lower cost

  18. Effects of embedded SHM sensors on the structural integrity of glass fiber/epoxy laminates under in-plane loads

    NASA Astrophysics Data System (ADS)

    Ghezzo, Fabrizia; Nemat-Nasser, Sia

    2007-04-01

    This experimental research is focused on examining the effects of stress concentration due to the embedded Structural Health Monitoring (SHM) sensors on the structural integrity of glass fiber/epoxy laminates subjected to in-plane tensile loads. Recent advances of health monitoring technologies have resulted in development of micro-dimensional sensors that can be embedded into composite laminates. Notwithstanding their small sizes, such inclusions may affect the response of the composite. Damage induced by the peak values of stress concentration around the embedded devices is, in fact, one of the main concerns. To assess this and related issues, we have fabricated a series of samples with and without embedded (dummy) sensors and micro-processors in S2 glass fiber/epoxy laminates, and systematically tested the samples while continuously monitoring the response by the acoustic emission technique. In this manner we have sought to address the process of damage initiation and evolution within the material. The results show that acoustic events begin earlier on during the loading process, in specimens with embedded sensors and the source of the damage is located near the sensors. These early events are associated with matrix failure at the sensor-resin interfaces through micrographic observations.

  19. SVAS3: Strain Vector Aided Sensorization of Soft Structures

    PubMed Central

    Culha, Utku; Nurzaman, Surya G.; Clemens, Frank; Iida, Fumiya

    2014-01-01

    Soft material structures exhibit high deformability and conformability which can be useful for many engineering applications such as robots adapting to unstructured and dynamic environments. However, the fact that they have almost infinite degrees of freedom challenges conventional sensory systems and sensorization approaches due to the difficulties in adapting to soft structure deformations. In this paper, we address this challenge by proposing a novel method which designs flexible sensor morphologies to sense soft material deformations by using a functional material called conductive thermoplastic elastomer (CTPE). This model-based design method, called Strain Vector Aided Sensorization of Soft Structures (SVAS3), provides a simulation platform which analyzes soft body deformations and automatically finds suitable locations for CTPE-based strain gauge sensors to gather strain information which best characterizes the deformation. Our chosen sensor material CTPE exhibits a set of unique behaviors in terms of strain length electrical conductivity, elasticity, and shape adaptability, allowing us to flexibly design sensor morphology that can best capture strain distributions in a given soft structure. We evaluate the performance of our approach by both simulated and real-world experiments and discuss the potential and limitations. PMID:25036332

  20. A Vision-Based Sensor for Noncontact Structural Displacement Measurement.

    PubMed

    Feng, Dongming; Feng, Maria Q; Ozer, Ekin; Fukuda, Yoshio

    2015-07-09

    Conventional displacement sensors have limitations in practical applications. This paper develops a vision sensor system for remote measurement of structural displacements. An advanced template matching algorithm, referred to as the upsampled cross correlation, is adopted and further developed into a software package for real-time displacement extraction from video images. By simply adjusting the upsampling factor, better subpixel resolution can be easily achieved to improve the measurement accuracy. The performance of the vision sensor is first evaluated through a laboratory shaking table test of a frame structure, in which the displacements at all the floors are measured by using one camera to track either high-contrast artificial targets or low-contrast natural targets on the structural surface such as bolts and nuts. Satisfactory agreements are observed between the displacements measured by the single camera and those measured by high-performance laser displacement sensors. Then field tests are carried out on a railway bridge and a pedestrian bridge, through which the accuracy of the vision sensor in both time and frequency domains is further confirmed in realistic field environments. Significant advantages of the noncontact vision sensor include its low cost, ease of operation, and flexibility to extract structural displacement at any point from a single measurement.

  1. A Vision-Based Sensor for Noncontact Structural Displacement Measurement

    PubMed Central

    Feng, Dongming; Feng, Maria Q.; Ozer, Ekin; Fukuda, Yoshio

    2015-01-01

    Conventional displacement sensors have limitations in practical applications. This paper develops a vision sensor system for remote measurement of structural displacements. An advanced template matching algorithm, referred to as the upsampled cross correlation, is adopted and further developed into a software package for real-time displacement extraction from video images. By simply adjusting the upsampling factor, better subpixel resolution can be easily achieved to improve the measurement accuracy. The performance of the vision sensor is first evaluated through a laboratory shaking table test of a frame structure, in which the displacements at all the floors are measured by using one camera to track either high-contrast artificial targets or low-contrast natural targets on the structural surface such as bolts and nuts. Satisfactory agreements are observed between the displacements measured by the single camera and those measured by high-performance laser displacement sensors. Then field tests are carried out on a railway bridge and a pedestrian bridge, through which the accuracy of the vision sensor in both time and frequency domains is further confirmed in realistic field environments. Significant advantages of the noncontact vision sensor include its low cost, ease of operation, and flexibility to extract structural displacement at any point from a single measurement. PMID:26184197

  2. Micro-swimming without flagella: Propulsion by internal structures

    NASA Astrophysics Data System (ADS)

    Ehlers, Kurt M.; Koiller, Jair

    2011-12-01

    Since a first proof-of-concept for an autonomous micro-swimming device appeared in 2005 a strong interest on the subject ensued. The most common configuration consists of a cell driven by an external propeller, bio-inspired by bacteria such as E.coli. It is natural to investigate whether micro-robots powered by internal mechanisms could be competitive. We compute the translational and rotational velocity of a spheroid that produces a helical wave on its surface, as has been suggested for the rod-shaped cyanobacterium Synechococcus. This organisms swims up to ten body lengths per second without external flagella. For the mathematical analysis we employ the tangent plane approximation method, which is adequate for amplitudes, frequencies and wave lengths considered here. We also present a qualitative discussion about the efficiency of a device driven by an internal rotating structure.

  3. Spiral Passive Electromagnetic Sensor (SPES) for composite structural changes in aircraft structures

    NASA Astrophysics Data System (ADS)

    Iervolino, Onorio; Meo, Michele

    2016-04-01

    A major goal of structural health monitoring (SHM) is to provide accurate and responsive detection and monitoring of flaws. This research work reports an investigation of SPES sensors for damage detection, investigating different sensor sizes and how they affect the sensor's signal. A sensor able to monitor structural change that can be remotely interrogated and does not need a power supply is presented in this work. The SPES-sensor presents the great advantage of monitoring conductive and non-conductive structures such as fiberglass-reinforced composites (FRC) and carbon fiber-reinforced polymers (CFRP). Any phenomena that affect the magnetic field of the SPES can be detected and monitored. A study was conducted to investigate the capability of sensor to give information on structural changes, simulated by the presence of an external mass placed in the proximity of sensor. Effect of different positions of the SPES within the sample, and how to extend the area of inspection using multiple sensors was investigated. The sensor was tested embedded in the samples, simulating the structural change on both sides of the sample. In both configurations the sensor described herein demonstrated a great potential to monitor structural changes.

  4. Investigation of the Frequency Shift of a SAD Circuit Loop and the Internal Micro-Cantilever in a Gas Sensor

    PubMed Central

    Guan, Liu; Zhao, Jiahao; Yu, Shijie; Li, Peng; You, Zheng

    2010-01-01

    Micro-cantilever sensors for mass detection using resonance frequency have attracted considerable attention over the last decade in the field of gas sensing. For such a sensing system, an oscillator circuit loop is conventionally used to actuate the micro-cantilever, and trace the frequency shifts. In this paper, gas experiments are introduced to investigate the mechanical resonance frequency shifts of the micro-cantilever within the circuit loop(mechanical resonance frequency, MRF) and resonating frequency shifts of the electric signal in the oscillator circuit (system working frequency, SWF). A silicon beam with a piezoelectric zinc oxide layer is employed in the experiment, and a Self-Actuating-Detecting (SAD) circuit loop is built to drive the micro-cantilever and to follow the frequency shifts. The differences between the two resonating frequencies and their shifts are discussed and analyzed, and a coefficient α related to the two frequency shifts is confirmed. PMID:22163588

  5. A novel method for in-situ monitoring of local voltage, temperature and humidity distributions in fuel cells using flexible multi-functional micro sensors.

    PubMed

    Lee, Chi-Yuan; Fan, Wei-Yuan; Chang, Chih-Ping

    2011-01-01

    In this investigation, micro voltage, temperature and humidity sensors were fabricated and integrated for the first time on a stainless steel foil using micro-electro-mechanical systems (MEMS). These flexible multi-functional micro sensors have the advantages of high temperature resistance, flexibility, smallness, high sensitivity and precision of location. They were embedded in a proton exchange membrane fuel cell (PEMFC) and used to simultaneously measure variations in the inner voltage, temperature and humidity. The accuracy and reproducibility of the calibrated results obtained using the proposed micro sensors is excellent. The experimental results indicate that, at high current density and 100%RH or 75%RH, the relative humidity midstream and downstream saturates due to severe flooding. The performance of the PEM fuel cell can be stabilized using home-made flexible multi-functional micro sensors by the in-situ monitoring of local voltage, temperature and humidity distributions within it.

  6. A Novel Method for In-Situ Monitoring of Local Voltage, Temperature and Humidity Distributions in Fuel Cells Using Flexible Multi-Functional Micro Sensors

    PubMed Central

    Lee, Chi-Yuan; Fan, Wei-Yuan; Chang, Chih-Ping

    2011-01-01

    In this investigation, micro voltage, temperature and humidity sensors were fabricated and integrated for the first time on a stainless steel foil using micro-electro-mechanical systems (MEMS). These flexible multi-functional micro sensors have the advantages of high temperature resistance, flexibility, smallness, high sensitivity and precision of location. They were embedded in a proton exchange membrane fuel cell (PEMFC) and used to simultaneously measure variations in the inner voltage, temperature and humidity. The accuracy and reproducibility of the calibrated results obtained using the proposed micro sensors is excellent. The experimental results indicate that, at high current density and 100%RH or 75%RH, the relative humidity midstream and downstream saturates due to severe flooding. The performance of the PEM fuel cell can be stabilized using home-made flexible multi-functional micro sensors by the in-situ monitoring of local voltage, temperature and humidity distributions within it. PMID:22319361

  7. Control systems using modal domain optical fiber sensors for smart structure applications

    NASA Technical Reports Server (NTRS)

    Lindner, Douglas K.; Reichard, Karl M.

    1991-01-01

    Recently, a new class of sensors has emerged for structural control which respond to environmental changes over a significant gauge length; these sensors are called distributed-effect sensors. These sensors can be fabricated with spatially varying sensitivity to the distributed measurand, and can be configured to measure a variety of structural parameters which can not be measured directly using point sensors. Examples of distributed-effect sensors include piezoelectric film, holographic sensors, and modal domain optical fiber sensors. Optical fiber sensors are particularly attractive for smart structure applications because they are flexible, have low mass, and can easily be embedded directly into materials. In this paper we describe the implementation of weighted modal domain optical fiber sensors. The mathematical model of the modal domain optical fiber sensor model is described and used to derive an expression for the sensor sensitivity. The effects of parameter variations on the sensor sensitivity are demonstrated to illustrate methods of spatially varying the sensor sensitivity.

  8. Degradation mechanism of a high-performance real micro gas sensor, as determined by spatially resolved XAFS.

    PubMed

    Wada, Takahiro; Murata, Naoyoshi; Uehara, Hiromitsu; Suzuki, Takuya; Nitani, Hiroaki; Niwa, Yasuhiro; Uo, Motohiro; Asakura, Kiyotaka

    2016-03-14

    Of late, battery-driven high-performance gas sensors have gained acceptability in practical usage, whose atomic-scale structure has been revealed by μ-fluorescence X-ray absorption fine structure analysis. We studied the chemical distribution of Pd species in the Pd/Al2O3 catalyst overlayer in the real gas sensor at various degrees of deterioration. In a freshly prepared sensor, all Pd species were in the PdO form; in a heavily deteriorated sensor, Pd/Al2O3 in the external region changed to metallic Pd particles, while the PdO structure in the inner region near the heater remained unchanged. The Pd species distribution was in agreement with the simulated thermal distribution. Temperature control was crucial to maintain the high performance of the gas sensor. The improved sensor allows homogeneous heating and has a lifetime of more than 5 years.

  9. Diagnosis and sensor validation through knowledge of structure and function

    NASA Technical Reports Server (NTRS)

    Scarl, Ethan A.; Jamieson, John R.; Delaune, Carl I.

    1987-01-01

    The liquid oxygen expert system 'LES' is proposed as the first capable of diagnostic reasoning from sensor data, using model-based knowledge of structure and function to find the expected state of all system objects, including sensors. The approach is generally algorithmic rather than heuristic, and represents uncertainties as sets of possibilities. Functional relationships are inverted to determine hypothetical values for potentially faulty objects, and may include conditional functions not normally considered to have inverses.

  10. Optical Fiber Sensors for Aircraft Structural Health Monitoring

    PubMed Central

    García, Iker; Zubia, Joseba; Durana, Gaizka; Aldabaldetreku, Gotzon; Illarramendi, María Asunción; Villatoro, Joel

    2015-01-01

    Aircraft structures require periodic and scheduled inspection and maintenance operations due to their special operating conditions and the principles of design employed to develop them. Therefore, structural health monitoring has a great potential to reduce the costs related to these operations. Optical fiber sensors applied to the monitoring of aircraft structures provide some advantages over traditional sensors. Several practical applications for structures and engines we have been working on are reported in this article. Fiber Bragg gratings have been analyzed in detail, because they have proved to constitute the most promising technology in this field, and two different alternatives for strain measurements are also described. With regard to engine condition evaluation, we present some results obtained with a reflected intensity-modulated optical fiber sensor for tip clearance and tip timing measurements in a turbine assembled in a wind tunnel. PMID:26134107

  11. Optical Fiber Sensors for Aircraft Structural Health Monitoring.

    PubMed

    García, Iker; Zubia, Joseba; Durana, Gaizka; Aldabaldetreku, Gotzon; Illarramendi, María Asunción; Villatoro, Joel

    2015-06-30

    Aircraft structures require periodic and scheduled inspection and maintenance operations due to their special operating conditions and the principles of design employed to develop them. Therefore, structural health monitoring has a great potential to reduce the costs related to these operations. Optical fiber sensors applied to the monitoring of aircraft structures provide some advantages over traditional sensors. Several practical applications for structures and engines we have been working on are reported in this article. Fiber Bragg gratings have been analyzed in detail, because they have proved to constitute the most promising technology in this field, and two different alternatives for strain measurements are also described. With regard to engine condition evaluation, we present some results obtained with a reflected intensity-modulated optical fiber sensor for tip clearance and tip timing measurements in a turbine assembled in a wind tunnel.

  12. Improved structures for evanescent wave sensors

    NASA Astrophysics Data System (ADS)

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

    1995-03-01

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

  13. High Performance Micro CO Sensors Based on ZnO-SnO2 Composite Nanofibers with Anti-Humidity Characteristics

    NASA Astrophysics Data System (ADS)

    Yue, Xue-Jun; Hong, Tian-Sheng; Xiang, Wei; Cai, Kun; Xu, Xing

    2012-12-01

    ZnO-SnO2 composite nanofibers are synthesized via an electrospinning method and characterized by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Micro sensors are fabricated by spinning the nanofibers on Si substrates with Pt signal and heater electrodes. The sensors with small areas (600 μm × 200 μm) can detect CO down to 1ppm at 360 °C. The corresponding sensitivity, response time, and recovery time are 3.2, 6s, and 11s, respectively. Importantly, the sensors can operate at high humidity conditions. The sensitivity only decreases to 2.3 when the sensors are exposed to 1 ppm CO at 95% relative humidity. These excellent sensing properties are due to combining the benefits of one-dimensional nanomaterials and the ZnO-SnO2 grain boundary in the nanofibers.

  14. Molecular structure and thermodynamic predictions to create highly sensitive microRNA biosensors.

    PubMed

    Larkey, Nicholas E; Brucks, Corinne N; Lansing, Shan S; Le, Sophia D; Smith, Natasha M; Tran, Victoria; Zhang, Lulu; Burrows, Sean M

    2016-02-25

    Many studies have established microRNAs (miRNAs) as post-transcriptional regulators in a variety of intracellular molecular processes. Abnormal changes in miRNA have been associated with several diseases. However, these changes are sometimes subtle and occur at nanomolar levels or lower. Several biosensing hurdles for in situ cellular/tissue analysis of miRNA limit detection of small amounts of miRNA. Of these limitations the most challenging are selectivity and sensor degradation creating high background signals and false signals. Recently we developed a reporter+probe biosensor for let-7a that showed potential to mitigate false signal from sensor degradation. Here we designed reporter+probe biosensors for miR-26a-2-3p and miR-27a-5p to better understand the effect of thermodynamics and molecular structures of the biosensor constituents on the analytical performance. Signal changes from interactions between Cy3 and Cy5 on the reporters were used to understand structural aspects of the reporter designs. Theoretical thermodynamic values, single stranded conformations, hetero- and homodimerization structures, and equilibrium concentrations of the reporters and probes were used to interpret the experimental observations. Studies of the sensitivity and selectivity revealed 5-9 nM detection limits in the presence and absence of interfering off-analyte miRNAs. These studies will aid in determining how to rationally design reporter+probe biosensors to overcome hurdles associated with highly sensitive miRNA biosensing.

  15. Structural integrated sensor and actuator systems for active flow control

    NASA Astrophysics Data System (ADS)

    Behr, Christian; Schwerter, Martin; Leester-Schädel, Monika; Wierach, Peter; Dietzel, Andreas; Sinapius, Michael

    2016-04-01

    An adaptive flow separation control system is designed and implemented as an essential part of a novel high-lift device for future aircraft. The system consists of MEMS pressure sensors to determine the flow conditions and adaptive lips to regulate the mass flow and the velocity of a wall near stream over the internally blown Coanda flap. By the oscillating lip the mass flow in the blowing slot changes dynamically, consequently the momentum exchange of the boundary layer over a high lift flap required mass flow can be reduced. These new compact and highly integrated systems provide a real-time monitoring and manipulation of the flow conditions. In this context the integration of pressure sensors into flow sensing airfoils of composite material is investigated. Mechanical and electrical properties of the integrated sensors are investigated under mechanical loads during tensile tests. The sensors contain a reference pressure chamber isolated to the ambient by a deformable membrane with integrated piezoresistors connected as a Wheatstone bridge, which outputs voltage signals depending on the ambient pressure. The composite material in which the sensors are embedded consists of 22 individual layers of unidirectional glass fiber reinforced plastic (GFRP) prepreg. The results of the experiments are used for adapting the design of the sensors and the layout of the laminate to ensure an optimized flux of force in highly loaded structures primarily for future aeronautical applications. It can be shown that the pressure sensor withstands the embedding process into fiber composites with full functional capability and predictable behavior under stress.

  16. Three Dimensional Visualization of Vibration of Civil Structure with Multisite Wireless Sensor Nodes

    NASA Astrophysics Data System (ADS)

    Takamoto, Tatsunao; Yamaguchi, Masayoshi; Nakahata, Kazuyuki; Ohga, Mitao

    The acceleration sensors which adopt the MEMS (Micro Electro Mechanical System) technology, offer high reliability and sensitivity in a small size. Using the MEMS sensor, we develop a visualization system of vibration of a civil structure at a low cost. In our system, time series of acceleration data measured at multiple points are transmitted to a computer at base-station with the wireless LAN and then converted to displacement data by the linear acceleration method. Here we make a digital filter to avoid a drift of the baseline of displacement data and to eliminate the white noise. First, our measurement setup and data conversion from acceleration to displacement using digital filters are described. Next we show an animation of vibration of a connecting bridge between two buildings by means of triaxial displacement data.

  17. HIgh-Q Optical Micro-cavity Resonators as High Sensitive Bio-chemical and Ultrasonic Sensors

    NASA Astrophysics Data System (ADS)

    Ling, Tao

    Optical micro-cavity resonators have quickly emerged in the past few years as a new sensing platform in a wide range of applications, such as bio-chemical molecular detection, environmental monitoring, acoustic and electromagnetic waves detection. In this thesis, we will mainly focus on developing high sensitivity silica micro-tube resonator bio-chemical sensors and high sensitivity polymer micro-ring resonator acoustic sensors. In high sensitivity silica micro-tube resonator bio-chemical sensors part: We first demonstrated a prism coupled silica micro-tube bio-chemical sensing platform to overcome the reliability problem in a fiber coupled thin wall silica micro-tube sensing platform. In refractive index sensing experiment, a unique resonance mode with sensitivity around 600nm/refractive index unit (RIU) has been observed. Surface sensing experiments also have been performed in this platform to detect lipid monolayer, lipid bilayer, electrostatic self assemble layer-by-layer as well as the interaction between the lipid bilayer and proteins. Then a theoretical study on various sensing properties on the silica micro-tube based sensing platform has been realized. Furthermore, we have proposed a coupled cavity system to further enhance the device's sensitivity above 1000nm/RIU. In high sensitivity polymer micro-ring resonator acoustic sensors part: We first presented a simplified fabrication process and realized a polymer microring with a Q factor around 6000. The fabricated device has been used to detect acoustic wave with noise equivalent pressure (NEP) around 230Pa over 1-75MHz frequency rang, which is comparable to state-of-art piezoelectric transducer and the device's frequency response also have been characterized to be up to 90MHz. A new fabrication process combined with resist reflow and thermal oxidation process has been used to improve the Q factor up to 10 5 and the device's NEP has been tested to be around 88Pa over 1-75MHz range. Further improving the

  18. Laser induced formation of micro-rough structures

    NASA Astrophysics Data System (ADS)

    Singh, Rajiv K.; Fitz-Gerald, James M.

    1997-01-01

    Laser induced micro-rough structures (LIMS) are a by-product of laser ablation process and are created during multiple pulse irradiation on the surface of the material. Although LIMS have been found to be deleterious for the thin film deposition process, these surfaces have wide variety of applications in synthesis of adherent coatings in thermal expansion mismatched systems. Earlier models, based on interference effects of the laser beam, to explain the evolution of LIMS, are not consistent with the experimental results. Experiments were conducted on a wide variety of materials (e.g. SiC, alumina, YBaCuO superconductor, etc.) to understand the mechanisms for generation of the micro-rough structures. A novel model was developed to explain the characteristics of LIMS such as (i) feature orientation (ii) evolution of surface structures as a function of pulses, (iii) formation of LIMS within a energy window near ablation threshold and (iv) periodicity which is independent of the laser wavelength and incident angle.

  19. Multiscale FE method for analysis of bone micro-structures.

    PubMed

    Podshivalov, L; Fischer, A; Bar-Yoseph, P Z

    2011-08-01

    Bones are composed of hierarchical bio-composite materials characterized by complex multiscale structural geometry and behavior. The architecture and the mechanical properties of bone tissue differ at each level of hierarchy. Thus, a multiscale approach for mechanical analysis of bone is imperative. This paper proposes a new approach for 3D multiscale finite element analysis of trabecular bone that can offer physicians a "digital magnifying glass" to facilitate continuous transition between macro- and micro-scales. The approach imitates the human ability to perceive details. That is, zooming-out from an object causes fewer details to be visible. As a result, the material appears to be smoother and more homogeneous. Zooming-in, in contrast, reveals additional details and material heterogeneity. Realization of the proposed approach requires synergy between a hierarchical geometric model for representing intermediate scales and a mechanical model for local material properties of bone tissue for each scale. The geometric model facilitates seamless and continuous bi-directional transition between macro- and micro-scales, while the mechanical model preserves the effective material properties. A 2D model of a simplified trabecular structure was implemented and analyzed in order to assess the feasibility of the proposed multiscale approach. The successful results of this model led to extending the method into 3D and analyzing real trabecular structures.

  20. Surface biofunctionalization and production of miniaturized sensor structures using aerosol printing technologies.

    PubMed

    Grunwald, Ingo; Groth, Esther; Wirth, Ingo; Schumacher, Julian; Maiwald, Marcus; Zoellmer, Volker; Busse, Matthias

    2010-03-01

    The work described in this paper demonstrates that very small protein and DNA structures can be applied to various substrates without denaturation using aerosol printing technology. This technology allows high-resolution deposition of various nanoscaled metal and biological suspensions. Before printing, metal and biological suspensions were formulated and then nebulized to form an aerosol which is aerodynamically focused on the printing module of the system in order to achieve precise structuring of the nanoscale material on a substrate. In this way, it is possible to focus the aerosol stream at a distance of about 5 mm from the printhead to the surface. This technology is useful for printing fluorescence-marked proteins and printing enzymes without affecting their biological activity. Furthermore, higher molecular weight DNA can be printed without shearing. The advantages, such as printing on complex, non-planar 3D structured surfaces, and disadvantages of the aerosol printing technology are also discussed and are compared with other printing technologies. In addition, miniaturized sensor structures with line thicknesses in the range of a few micrometers are fabricated by applying a silver sensor structure to glass. After sintering using an integrated laser or in an oven process, electrical conductivity is achieved within the sensor structure. Finally, we printed BSA in small micrometre-sized areas within the sensor structure using the same deposition system. The aerosol printing technology combined with material development offers great advantages for future-oriented applications involving biological surface functionalization on small areas. This is important for innovative biomedical micro-device development and for production solutions which bridge the disciplines of biology and electronics.

  1. Carbon Nanotube-Based Structural Health Monitoring Sensors

    NASA Technical Reports Server (NTRS)

    Wincheski, Russell; Jordan, Jeffrey; Oglesby, Donald; Watkins, Anthony; Patry, JoAnne; Smits, Jan; Williams, Phillip

    2011-01-01

    Carbon nanotube (CNT)-based sensors for structural health monitoring (SHM) can be embedded in structures of all geometries to monitor conditions both inside and at the surface of the structure to continuously sense changes. These CNTs can be manipulated into specific orientations to create small, powerful, and flexible sensors. One of the sensors is a highly flexible sensor for crack growth detection and strain field mapping that features a very dense and highly ordered array of single-walled CNTs. CNT structural health sensors can be mass-produced, are inexpensive, can be packaged in small sizes (0.5 micron(sup 2)), require less power than electronic or piezoelectric transducers, and produce less waste heat per square centimeter than electronic or piezoelectric transducers. Chemically functionalized lithographic patterns are used to deposit and align the CNTs onto metallic electrodes. This method consistently produces aligned CNTs in the defined locations. Using photo- and electron-beam lithography, simple Cr/Au thin-film circuits are patterned onto oxidized silicon substrates. The samples are then re-patterned with a CNT-attracting, self-assembled monolayer of 3-aminopropyltriethoxysilane (APTES) to delineate the desired CNT locations between electrodes. During the deposition of the solution-suspended single- wall CNTs, the application of an electric field to the metallic contacts causes alignment of the CNTs along the field direction. This innovation is a prime candidate for smart skin technologies with applications ranging from military, to aerospace, to private industry.

  2. Bio-inspired sensor skins for structural health monitoring

    NASA Astrophysics Data System (ADS)

    Tata, Uday; Deshmukh, S.; Chiao, J. C.; Carter, Ronald; Huang, H.

    2009-10-01

    This paper presents the simulation and experimental work that proved the feasibility of using a patch antenna for strain measurement. A patch antenna, besides serving as a data transmitting device, can function as a transducer that directly encodes the strain experienced into its resonant frequency. Printed on a flexible substrate, the antenna sensor is small in size, has a low profile and can be conformal to any attached surface. The technique for interrogating the antenna sensor using a wireless non-contact method is also demonstrated. Without needing electric wiring for power supply and data transmitting, the antenna sensor has a great potential for the realization of engineered sensor skins that imitate the sense of pain for structural health monitoring purposes.

  3. Highly sensitive bending sensor based on multimode-multimode-coreoffset fiber structure

    NASA Astrophysics Data System (ADS)

    Qi, Yanhui; Ma, Lin; Sun, Jiang; Kang, Zexin; Bai, Yunlong; Jian, Shuisheng

    2015-12-01

    In this paper, we present a simple fiber optic bending sensor based on the multimode-multimode structure combining with the core-offset fiber structure. The multimode-multimode structure is composed of no core fiber (NCF) with hundreds of micrometers in length as a micro-lens for mode conversion, and single mode fiber (SMF) which can be seen as a section of special multimode fiber (MMF) when considered the cladding modes. The transmission spectrum in the experiment agrees well with the numerical model. The sensitivity of the structure can be achieved as high as 11.104 nm/m-1 in the measuring range. Meanwhile, the sensitivity of the neighboring resonance wavelength around 1546 nm exhibits approximately the same sensitivity which is 10.579 nm/m-1. Besides, the strain sensitivity is about -0.927 pm/με within the measuring strain range.

  4. Scheduling policies of intelligent sensors and sensor/actuators in flexible structures

    NASA Astrophysics Data System (ADS)

    Demetriou, Michael A.; Potami, Raffaele

    2006-03-01

    In this note, we revisit the problem of actuator/sensor placement in large civil infrastructures and flexible space structures within the context of spatial robustness. The positioning of these devices becomes more important in systems employing wireless sensor and actuator networks (WSAN) for improved control performance and for rapid failure detection. The ability of the sensing and actuating devices to possess the property of spatial robustness results in reduced control energy and therefore the spatial distribution of disturbances is integrated into the location optimization measures. In our studies, the structure under consideration is a flexible plate clamped at all sides. First, we consider the case of sensor placement and the optimization scheme attempts to produce those locations that minimize the effects of the spatial distribution of disturbances on the state estimation error; thus the sensor locations produce state estimators with minimized disturbance-to-error transfer function norms. A two-stage optimization procedure is employed whereby one first considers the open loop system and the spatial distribution of disturbances is found that produces the maximal effects on the entire open loop state. Once this "worst" spatial distribution of disturbances is found, the optimization scheme subsequently finds the locations that produce state estimators with minimum transfer function norms. In the second part, we consider the collocated actuator/sensor pairs and the optimization scheme produces those locations that result in compensators with the smallest norms of the disturbance-to-state transfer functions. Going a step further, an intelligent control scheme is presented which, at each time interval, activates a subset of the actuator/sensor pairs in order provide robustness against spatiotemporally moving disturbances and minimize power consumption by keeping some sensor/actuators in sleep mode.

  5. Micro-electromechanical film bulk acoustic sensor for plasma and whole blood coagulation monitoring.

    PubMed

    Chen, Da; Song, Shuren; Ma, Jilong; Zhang, Zhen; Wang, Peng; Liu, Weihui; Guo, Qiuquan

    2017-05-15

    Monitoring blood coagulation is an important issue in the surgeries and the treatment of cardiovascular diseases. In this work, we reported a novel strategy for the blood coagulation monitoring based on a micro-electromechanical film bulk acoustic resonator. The resonator was excited by a lateral electric field and operated under the shear mode with a frequency of 1.9GHz. According to the apparent step-ladder curves of the frequency response to the change of blood viscoelasticity, the coagulation time (prothrombin time) and the coagulation kinetics were measured with the sample consumption of only 1μl. The procoagulant activity of thromboplastin and the anticoagulant effect of heparin on the blood coagulation process were illustrated exemplarily. The measured prothrombin times showed a good linear correlation with R(2)=0.99969 and a consistency with the coefficient of variation less than 5% compared with the commercial coagulometer. The proposed film bulk acoustic sensor, which has the advantages of small size, light weight, low cost, simple operation and little sample consumption, is a promising device for miniaturized, online and automated analytical system for routine diagnostics of hemostatic status and personal health monitoring.

  6. Electron tunnel sensor technology

    NASA Technical Reports Server (NTRS)

    Kenny, T. W.; Waltman, S. B.; Reynolds, J. K.; Kaiser, W. J.

    1991-01-01

    Researchers designed and constructed a novel electron tunnel sensor which takes advantage of the mechanical properties of micro-machined silicon. For the first time, electrostatic forces are used to control the tunnel electrode separation, thereby avoiding the thermal drift and noise problems associated with piezoelectric actuators. The entire structure is composed of micro-machined silicon single crystals, including a folded cantilever spring and a tip. The application of this sensor to the development of a sensitive accelerometer is described.

  7. Micro-Machined Thin Film Sensor Arrays For The Detection Of H2, Containing Gases, And Method Of Making And Using The Same.

    DOEpatents

    DiMeo, Jr., Frank; Baum, Thomas H.

    2003-07-22

    The present invention provides a hydrogen sensor including a thin film sensor element formed by metal organic chemical vapor deposition (MOCVD) or physical vapor deposition (PVD), on a micro-hotplate structure. The thin film sensor element includes a film of a hydrogen-interactive metal film that reversibly interacts with hydrogen to provide a correspondingly altered response characteristic, such as optical transmissivity, electrical conductance, electrical resistance, electrical capacitance, magneto resistance, photoconductivity, etc., relative to the response characteristic of the film in the absence of hydrogen. The hydrogen-interactive metal film may be overcoated with a thin film hydrogen-permeable barrier layer to protect the hydrogen-interactive film from deleterious interaction with non-hydrogen species. The hydrogen permeable barrier may comprise species to scavenge oxygen and other like species. The hydrogen sensor of the invention may be usefully employed for the detection of hydrogen in an environment susceptible to the incursion or generation of hydrogen and may be conveniently configured as a hand-held apparatus.

  8. Integration of periodic structure and highly narrowband MEMS sensor to enhance crack detection ability in steel structures

    NASA Astrophysics Data System (ADS)

    Kabir, Minoo; Ozevin, Didem

    2016-09-01

    Acoustic emission method is a nondestructive evaluation method based on the propagation of elastic waves due to the sudden change in strain field caused by newly formed fracture surfaces. While the method has been successfully applied to many structures, the influence of friction emissions limits the diverse use of the method in large-scale structures. This research integrates the metamaterial geometry to block low frequency friction signals while allowing high frequency signals due to the crack growth. The phononic structure is composed of periodic arrangement of holes in a steel plate that prohibits propagation of elastic waves near the band gap of 60 kHz. The dispersion curve of the periodic structure is calculated using finite element modeling of a unit cell in COMSOL Multiphysics. As the band gap of the periodic structure is highly narrowband, the acoustic sensing is achieved by highly narrowband capacitive type Micro-Electro- Mechanical Systems (MEMS) sensors tuned to the desired stop band frequency. The integration of periodic plate design and MEMS sensors provides wave-field focusing to reduce wave attenuation, and prevent interference of secondary waves sources, such as friction, with the primary waveforms. The waveguiding feature of the designed structure is experimentally investigated and discussed in this paper.

  9. Monitoring of slope-instabilities and deformations with Micro-Electro-Mechanical-Systems (MEMS) in wireless ad-hoc Sensor Networks

    NASA Astrophysics Data System (ADS)

    Arnhardt, C.; Fernández-Steeger, T. M.; Azzam, R.

    2009-04-01

    In most mountainous regions, landslides represent a major threat to human life, properties and infrastructures. Nowadays existing landslide monitoring systems are often characterized by high efforts in terms of purchase, installation, maintenance, manpower and material. In addition (or because of this) only small areas or selective points of the endangered zone can be observed by the system. Therefore the improvement of existing and the development of new monitoring and warning systems are of high relevance. The joint project "Sensor based Landslide Early Warning Systems" (SLEWS) deals with the development of a prototypic Alarm- and Early Warning system (EWS) for different types of landslides using low-cost micro-sensors (MEMS) integrated in a wireless sensor network (WSN). Modern so called Ad-Hoc, Multi-Hop wireless sensor networks (WSN) are characterized by a self organizing and self-healing capacity of the system (autonomous systems). The network consists of numerous individual and own energy-supply operating sensor nodes, that can send data packages from their measuring devices (here: MEMS) over other nodes (Multi-Hop) to a collection point (gateway). The gateway provides the interface to central processing and data retrieval units (PC, Laptop or server) outside the network. In order to detect and monitor the different landslide processes (like fall, topple, spreading or sliding) 3D MEMS capacitive sensors made from single silicon crystals and glass were chosen to measure acceleration, tilting and altitude changes. Based on the so called MEMS (Micro-Electro-Mechanical Systems) technology, the sensors combine very small mechanical and electronic units, sensing elements and transducers on a small microchip. The mass production of such type of sensors allows low cost applications in different areas (like automobile industries, medicine, and automation technology). Apart from the small and so space saving size and the low costs another advantage is the energy

  10. Micro/nanoscale continuous printing: direct-writing of wavy micro/nano structures via electrospinning

    NASA Astrophysics Data System (ADS)

    Fang, Feiyu; Du, Zefeng; Zeng, Jun; Zhu, Ziming; Chen, Xin; Chen, Xindu; Lv, Yuanjun; Wang, Han

    2015-07-01

    Micro/nanofibers that are created by direct-writing using an electrospinning (ES) technique have aroused much recent attention, owing to their intriguing physical properties and great potential as building blocks for micro/nanoscale devices. In this work, a wavy direct-writing (WDW) process was developed to directly write wavy micro/nanostructures suitable for the fabrication of micro/nanoscale devices. The low voltage WDW technique is anticipated to be useful for a broad range of applications including flexible/stretchable electronics, micro optoelectronics, nano-antennas, microelectromechanical systems (MEMS), and biomedical engineering.

  11. Analysis of the intermittent nature of the turbulence from micro-structure profiles

    NASA Astrophysics Data System (ADS)

    Sanchez, X.; Planella, J.; Roget, E.

    2012-04-01

    We present a statistical analysis of the intermittent nature of turbulence. One usually characterizes the nature of the intermittency with the scaling properties of the structure functions of the velocity or a scalar field, like the temperature. Oceanic measurements with a micro-structure profiler allow the determination of the transverse velocity structure functions. And following the refined Kolmogorov similarity hypothesis (K62), this scaling is directly related to the scaling of the rate of dissipation of turbulent kinetic energy. In aquatic ecosystems, turbulent oscillations of various scales influence aggregation, incubation and foraging processes of small-scale planktonic organisms. Internal intermittency can affect phyto and zooplankton species less than several millimeters in size, specifically, floating microscopic algae that are responsible for photosynthesis in coastal oceans. Zooplankton larger than 1 cm usually do not react to small-scale intermittency of turbulence. This is the first time, to our knowledge, that the structure functions come from space series. Previous results in air and in water were obtained from a static sensor in the atmosphere, ocean or in a laboratory setup. Furthermore, previous works were mainly focused on the longitudinal structure functions, while the results we present here relate to the transverse structure functions. Acknowledgments: This research was developed under the Spanish Government Project FIS2008-03608 and concluded within the framework of the CLIMSEAS project FP7-IRSES-2009 (ref. 247512).

  12. Measurement of Gas-Liquid Two-Phase Flow in Micro-Pipes by a Capacitance Sensor

    PubMed Central

    Ji, Haifeng; Li, Huajun; Huang, Zhiyao; Wang, Baoliang; Li, Haiqing

    2014-01-01

    A capacitance measurement system is developed for the measurement of gas-liquid two-phase flow in glass micro-pipes with inner diameters of 3.96, 2.65 and 1.56 mm, respectively. As a typical flow regime in a micro-pipe two-phase flow system, slug flow is chosen for this investigation. A capacitance sensor is designed and a high-resolution and high-speed capacitance measurement circuit is used to measure the small capacitance signals based on the differential sampling method. The performance and feasibility of the capacitance method are investigated and discussed. The capacitance signal is analyzed, which can reflect the voidage variation of two-phase flow. The gas slug velocity is determined through a cross-correlation technique using two identical capacitance sensors. The simulation and experimental results show that the presented capacitance measurement system is successful. Research work also verifies that the capacitance sensor is an effective method for the measurement of gas liquid two-phase flow parameters in micro-pipes. PMID:25587879

  13. Enhancing the sensitivity of a micro-diaphragm resonating sensor by effectively positioning the mass on the membrane

    PubMed Central

    Kim, Jinsik; Kim, Hye Jin; Cho, EunAe; Shin, Hyun-Joon; Park, Jung Ho; Hwang, Kyo Seon

    2015-01-01

    The detection of biomarkers in the liquid phase using mechanical sensors is difficult because of noise caused by the liquid. To reduce and verify the side effects of liquid loading, we performed calculations and experiments to determine the shift in resonant frequency according to the loading conditions. A 2-μm-thick piezoelectric rectangular micro-diaphragm with a 500 × 500 μm membrane was used. These dimensions were determined such that there would be an analogous resonant frequency shift ratio in both (1, 1) and (2, 2) modes. By calculating and measuring the resonant frequency, we verified that the resonant frequency of the sensor would change only through contact with the liquid, even the resonant frequency change by only liquid much higher than the changes caused by the nanoparticles. The real signal constituted only 0.017% of the initial resonant frequency. To enhance the sensitivity by reducing the unexpected surface stress in the liquid, the liquid was dropped onto the surface of the micro-diaphragm. This resulted in an improvement of more than 10 times the sensitivity in both modes. In addition, by controlling the position in the micro-diaphragm resonating sensor, more sensitive positions with large displacements were determined according to each mode. PMID:26594022

  14. Distinguishing between sensor fault, structural damage, and environmental or operational effects in structural health monitoring

    NASA Astrophysics Data System (ADS)

    Kullaa, Jyrki

    2011-11-01

    Discrimination between three different sources of variability in a vibration-based structural health monitoring system is investigated: environmental or operational effects, sensor faults, and structural damage. Separating the environmental or operational effects from the other two is based on the assumption that measurements under different environmental or operational conditions are included in the training data. Distinguishing between sensor fault and structural damage utilizes the fact that the sensor faults are local, while structural damage is global. By localizing the change to a sensor which is then removed from the network, the two different influences can be separated. The sensor network is modelled as a Gaussian process and the generalized likelihood ratio test (GLRT) is then used to detect and localize a change in the system. A numerical and an experimental study are performed to validate the proposed method.

  15. Multilayer structure for a spectral imaging sensor.

    PubMed

    Parrein, Pascale; Moussy, Norbert; Poupinet, Ludovic; Gidon, Pierre

    2009-01-20

    We investigate the possibility of recovering spectral information using a multilayer structure realized through microelectronics technologies and compatible with a matrix arrangement. The structure is made of photoabsorbing layers, acting as local photodetectors, alternating with transparent layers. The whole structure lies on a reflective surface. A stationary wave containing the spectral information of the source is generated within the structure. We determine the intensity of the stationary wave at any position, taking into account absorption and multireflections at each transition as well as the signal detected by the photoabsorbing layers. The model forecasting the detected signal is then validated using p-i-n diodes of different thicknesses made of hydrogenated amorphous silicon (a-Si:H) encompassed between indium tin oxide (ITO) electrodes. The detected signal depends on the wavelength of the incident light, the thickness of the detecting layer, and the latter's position within the structure. A specific spectral response can then be associated to each photoabsorbing layer. We show how spectral information can be retrieved from this kind of structure in the visible spectrum range.

  16. Investigation on spectral response of micro-cavity structure by symmetrical tapered fiber tips

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Li, Yang; Yan, Xiaojun; Li, Weidong

    2016-06-01

    We proposed and experimentally demonstrated a micro-cavity structure made of symmetrical tapered fiber tips. The waist of a conventional fiber taper fabricated from heating and stretching technique is symmetrically cleaved, and the aligned fiber tips with air gap constitute a Fabry-Perot micro-cavity due to the reflection at the tip facet. The spectral responses of such micro-cavity structure have been investigated both in beam propagation models and experiments. The multibeam interference in the micro-cavity and the impact of the waist diameter and cavity length on the spectral response has been successfully demonstrated. And a micro-cavity structure with 45 μm waist diameter was experimentally achieved, the measured spectra agree well with the simulation ones, indicating that the spectral response of the micro-cavity structure is contributed by both the multibeam interference and the Fabry-Perot micro-cavity.

  17. Embeddable structural sensors for SHM of solid rocket grains

    NASA Astrophysics Data System (ADS)

    Chelner, Herb; Buswell, Jim

    2006-05-01

    Structural Health Monitoring is essential in that any event that may compromise the solid rocket motor must be detected. The magnitude, position and time of any imposed event that may damage the propellant grain, bonding system or integrity of the case must be detected and identified for safe operation of the motor. The current embedded sensor technology has been developed to monitor the effect of these events on the propellant grain. Normal bond stress and temperature can be measured using DBST sensors and the output interpreted to confirm integrity. It has been shown that the presences of de-bond and cracks can be determined. Current work is in progress to establish if these embedded sensors can be used to determine position and size of such defects. The stress distribution in a typical propellant grain also has a shear component particularly near the ends and around any flaps, slots or stress relieving devices. This can be the critical stress under certain loads and in complex geometries. Therefore, a recent addition to the range is a sensor to measure shear stress in the same body as the DBST. Motors can be stored for long periods before being used so the sensor system must also be reliable and stable for at least twenty years of operation. Similar sensors stored for ten years have shown little change and tests are being undertaken to establish the confidence that the sensor system will last the life of the motor. This paper will review the recent development and testing of these embeddable sensors, and results to date will be discussed.

  18. Optimal sensor placement in structural health monitoring using discrete optimization

    NASA Astrophysics Data System (ADS)

    Sun, Hao; Büyüköztürk, Oral

    2015-12-01

    The objective of optimal sensor placement (OSP) is to obtain a sensor layout that gives as much information of the dynamic system as possible in structural health monitoring (SHM). The process of OSP can be formulated as a discrete minimization (or maximization) problem with the sensor locations as the design variables, conditional on the constraint of a given sensor number. In this paper, we propose a discrete optimization scheme based on the artificial bee colony algorithm to solve the OSP problem after first transforming it into an integer optimization problem. A modal assurance criterion-oriented objective function is investigated to measure the utility of a sensor configuration in the optimization process based on the modal characteristics of a reduced order model. The reduced order model is obtained using an iterated improved reduced system technique. The constraint is handled by a penalty term added to the objective function. Three examples, including a 27 bar truss bridge, a 21-storey building at the MIT campus and the 610 m high Canton Tower, are investigated to test the applicability of the proposed algorithm to OSP. In addition, the proposed OSP algorithm is experimentally validated on a physical laboratory structure which is a three-story two-bay steel frame instrumented with triaxial accelerometers. Results indicate that the proposed method is efficient and can be potentially used in OSP in practical SHM.

  19. Research and Development on In-Situ Measurement Sensors for Micro-Meteoroid and Small Space Debris at JAXA

    NASA Astrophysics Data System (ADS)

    Kitazawa, Yukihito; Matsumoto, Haruhisa; Okudaira, Osamu; Kimoto, Yugo; Hanada, Toshiya; Akahoshi, Yasuhiro; Pauline, Faure; Sakurai, Akira; Funakoshi, Kunihiro; Yasaka, Testuo

    2015-04-01

    The history of Japanese R&D into in-situ sensors for micro-meteoroid and orbital debris (MMOD) measurements is neither particularly long nor short. Research into active sensors started for the meteoroid observation experiment on the HITEN (MUSES-A) satellite of ISAS/JAXA launched in 1990, which had MDC (Munich Dust Counter) on-board sensors for micro meteoroid measurement. This was a collaboration between Technische Universität München and ISAS/JAXA. The main purpose behind the start of passive sensor research was SOCCOR, a late 80's Japan-US mission that planned to capture cometary dust and return to the Earth. Although this mission was canceled, the research outcomes were employed in a JAXA micro debris sample return mission using calibrated aerogel involving the Space Shuttle and the International Space Station. There have been many other important activities apart from the above, and the knowledge generated from them has contributed to JAXA's development of a new type of active dust sensor. JAXA and its partners have been developing a simple in-situ active dust sensor of a new type to detect dust particles ranging from a hundred micrometers to several millimeters. The distribution and flux of the debris in the size range are not well understood and is difficult to measure using ground observations. However, it is important that the risk caused by such debris is assessed. In-situ measurement of debris in this size range is useful for 1) verifying meteoroid and debris environment models, 2) verifying meteoroid and debris environment evolution models, and 3) the real time detection of explosions, collisions and other unexpected orbital events. Multitudes of thin, conductive copper strips are formed at a fine pitch of 100 um on a film 12.5 um thick of nonconductive polyimide. An MMOD particle impact is detected when one or more strips are severed by being perforated by such an impact. This sensor is simple to produce and use and requires almost no calibration as

  20. High Efficiency c-Silicon Solar Cells Based on Micro-Nanoscale Structure

    DTIC Science & Technology

    2011-06-01

    High Efficiency c- Silicon Solar Cells Based on Micro-nanoscale Structure by Fred Semendy, Priyalal Wijewarnasuriya, and Nibir K. Dhar...20783-1197 ARL-TR-5576 June 2011 High Efficiency c- Silicon Solar Cells Based on Micro-nanoscale Structure Fred Semendy and Priyalal...4. TITLE AND SUBTITLE High Efficiency c- Silicon Solar Cells Based on Micro-nanoscale Structure 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

  1. Structural configuration study for an acoustic wave sensor

    NASA Astrophysics Data System (ADS)

    Zhang, Biaobiao

    A continuous structure has several response characteristics that make it a candidate for a sensor used to locate an acoustic source. Primary goals in developing such a sensor structure are to ensure that the response is rich enough to provide information about the impinging acoustic wave and to detect the direction of travel without being too sensitive to background noise. As such, there are several factors that must be examined with regard to sensor configuration and measurement requirements. This dissertation describes a set of studies that examine various configuration requirements for such a sensor. Some of the parameters of interest include the size, or aperture of the structure, boundary conditions, material properties, and thickness. The response of the structure to transient sinusoidal wave excitations will be examined analytically. The time-domain response of an Euler-Bernoulli beam excited by a traveling sinusoidal excitation is obtained based on modal superposition and verified by using a finite element method. Then, an approach using simple basis functions will be applied to achieve the goal of more efficient response and force identification. The moving force is identified in the time domain by extending previous inverse approaches. The Tikhonov regularization technique provides bounds to the ill-conditioned results in the identification problem. Both simulated displacement and velocity are considered for use in the inverse. To evaluate the method and examine various configurations, simulations with different numbers of sinusoidal half-cycles exciting the sensor structure are studied. Various levels of random noise are also added to the simulated displacements and velocities responses in order to study the effect of noise in moving wave load identification. Such a new approach in acoustic sensing has applications in the areas of security and disaster recovery.

  2. AOI [3] High-Temperature Nano-Derived Micro-H2 and - H2S Sensors

    SciTech Connect

    Sabolsky, Edward M.

    2014-08-01

    The emissions from coal-fired power plants remain a significant concern for air quality. This environmental challenge must be overcome by controlling the emission of sulfur dioxide (SO2) and hydrogen sulfide (H2S) throughout the entire coal combustion process. One of the processes which could specifically benefit from robust, low cost, and high temperature compatible gas sensors is the coal gasification process which converts coal and/or biomass into syngas. Hydrogen (H2), carbon monoxide (CO) and sulfur compounds make up 33%, 43% and 2% of syngas, respectively. Therefore, development of a high temperature (>500°C) chemical sensor for in-situ monitoring of H2, H2S and SO22 levels during coal gasification is strongly desired. The selective detection of SO2/H2S in the presence of H2, is a formidable task for a sensor designer. In order to ensure effective operation of these chemical sensors, the sensor system must inexpensively function within harsh temperature and chemical environment. Currently available sensing approaches, which are based on gas chromatography, electrochemistry, and IR-spectroscopy, do not satisfy the required cost and performance targets. This work focused on the development microsensors that can be applied to this application. In order to develop the high- temperature compatible microsensor, this work addressed various issues related to sensor stability, selectivity, and miniaturization. In the research project entitled “High-Temperature Nano-Derived Micro-H2 and -H2S Sensors”, the team worked to develop micro-scale, chemical sensors and sensor arrays composed of nano-derived, metal-oxide composite materials to detect gases like H2, SO2, and H2S within high-temperature environments (>500°C). The research was completed in collaboration with NexTech Materials, Ltd. (Lewis Center, Ohio). Nex

  3. Design and Characterization of a Sensorized Microfluidic Cell-Culture System with Electro-Thermal Micro-Pumps and Sensors for Cell Adhesion, Oxygen, and pH on a Glass Chip

    PubMed Central

    Bonk, Sebastian M.; Stubbe, Marco; Buehler, Sebastian M.; Tautorat, Carsten; Baumann, Werner; Klinkenberg, Ernst-Dieter; Gimsa, Jan

    2015-01-01

    We combined a multi-sensor glass-chip with a microfluidic channel grid for the characterization of cellular behavior. The grid was imprinted in poly-dimethyl-siloxane. Mouse-embryonal/fetal calvaria fibroblasts (MC3T3-E1) were used as a model system. Thin-film platinum (Pt) sensors for respiration (amperometric oxygen electrode), acidification (potentiometric pH electrodes) and cell adhesion (interdigitated-electrodes structures, IDES) allowed us to monitor cell-physiological parameters as well as the cell-spreading behavior. Two on-chip electro-thermal micro-pumps (ETμPs) permitted the induction of medium flow in the system, e.g., for medium mixing and drug delivery. The glass-wafer technology ensured the microscopic observability of the on-chip cell culture. Connecting Pt structures were passivated by a 1.2 μm layer of silicon nitride (Si3N4). Thin Si3N4 layers (20 nm or 60 nm) were used as the sensitive material of the pH electrodes. These electrodes showed a linear behavior in the pH range from 4 to 9, with a sensitivity of up to 39 mV per pH step. The oxygen sensors were circular Pt electrodes with a sensor area of 78.5 μm2. Their sensitivity was 100 pA per 1% oxygen increase in the range from 0% to 21% oxygen (air saturated). Two different IDES geometries with 30- and 50-μm finger spacings showed comparable sensitivities in detecting the proliferation rate of MC3T3 cells. These cells were cultured for 11 days in vitro to test the biocompatibility, microfluidics and electric sensors of our system under standard laboratory conditions. PMID:26263849

  4. Structural Colour in Colourimetric Sensors and Indicators

    DTIC Science & Technology

    2013-07-11

    opal lms possess a highly selective wettability threshold for liquid inltration.93 Inltrationwas associated with a disappearance of the structure’s...based colourimetric indicator for liquids.95 We created an array of six indicators, each employing a vertical wettability gradient designed to exhibit...Yin and S. Kwon, Nat. Photonics, 2009, 3, 534. 33 A. M. Brozell, M. A. Muha, A. Abed -Amoli, D. Bricarello and A. N. Parikh, Nano Lett., 2007, 7

  5. Structural dynamics control the MicroRNA maturation pathway

    PubMed Central

    Dallaire, Paul; Tan, Huiping; Szulwach, Keith; Ma, Christopher; Jin, Peng; Major, François

    2016-01-01

    MicroRNAs (miRNAs) are crucial gene expression regulators and first-order suspects in the development and progression of many diseases. Comparative analysis of cancer cell expression data highlights many deregulated miRNAs. Low expression of miR-125a was related to poor breast cancer prognosis. Interestingly, a single nucleotide polymorphism (SNP) in miR-125a was located within a minor allele expressed by breast cancer patients. The SNP is not predicted to affect the ground state structure of the primary transcript or precursor, but neither the precursor nor mature product is detected by RT-qPCR. How this SNP modulates the maturation of miR-125a is poorly understood. Here, building upon a model of RNA dynamics derived from nuclear magnetic resonance studies, we developed a quantitative model enabling the visualization and comparison of networks of transient structures. We observed a high correlation between the distances between networks of variants with that of their respective wild types and their relative degrees of maturation to the latter, suggesting an important role of transient structures in miRNA homeostasis. We classified the human miRNAs according to pairwise distances between their networks of transient structures. PMID:27651454

  6. Plastic optical fibre sensor for damage detection in offshore structures

    NASA Astrophysics Data System (ADS)

    Kuang, K. S. C.; Koh, C. G.

    2009-12-01

    It is important to ensure the safe and reliable use of massive engineering structures such as offshore platforms, including all aspects of safety and design code compliance. Although routine inspection is an integral part of the safety protocol in operating and maintaining these structures, regular assessment of the effectiveness and efficiency of existing safety evaluation methods is clearly desired in view of emerging technologies for structural health monitoring of engineering structures. The recent advancement in plastic optical fibre (POF) materials and processing render POF sensors an attractive alternative to glass-based optical fibre sensors as they offer much greater being flexibility, high resistance to fracture and hence the ease in their handling and installation. In this paper, some preliminary results demonstrating the use of plastic optical fibre sensors for damage detection and structural health monitoring for offshore and marine-related applications will be summarized. In this study, POF will be used for crack detection in tubular steel specimens in conjunction with a high-resolution photon-counting optical time-domain reflectrometry (v-OTDR). Although the use of OTDR technique is an established method in the telecommunication industry, this study is new in that it is now possible, with the availability of v-OTDR and graded-index perfluorinated POF, to detect and locate the crack position in the host structure to within 10 cm accuracy or better. It will also be shown that this technique could readily be configured to monitor crack growth in steel tubular members.

  7. Plastic optical fibre sensor for damage detection in offshore structures

    NASA Astrophysics Data System (ADS)

    Kuang, K. S. C.; Koh, C. G.

    2010-03-01

    It is important to ensure the safe and reliable use of massive engineering structures such as offshore platforms, including all aspects of safety and design code compliance. Although routine inspection is an integral part of the safety protocol in operating and maintaining these structures, regular assessment of the effectiveness and efficiency of existing safety evaluation methods is clearly desired in view of emerging technologies for structural health monitoring of engineering structures. The recent advancement in plastic optical fibre (POF) materials and processing render POF sensors an attractive alternative to glass-based optical fibre sensors as they offer much greater being flexibility, high resistance to fracture and hence the ease in their handling and installation. In this paper, some preliminary results demonstrating the use of plastic optical fibre sensors for damage detection and structural health monitoring for offshore and marine-related applications will be summarized. In this study, POF will be used for crack detection in tubular steel specimens in conjunction with a high-resolution photon-counting optical time-domain reflectrometry (v-OTDR). Although the use of OTDR technique is an established method in the telecommunication industry, this study is new in that it is now possible, with the availability of v-OTDR and graded-index perfluorinated POF, to detect and locate the crack position in the host structure to within 10 cm accuracy or better. It will also be shown that this technique could readily be configured to monitor crack growth in steel tubular members.

  8. A time-based front-end ASIC for the silicon micro strip sensors of the bar PANDA Micro Vertex Detector

    NASA Astrophysics Data System (ADS)

    Di Pietro, V.; Brinkmann, K.-Th.; Riccardi, A.; Ritman, J.; Rivetti, A.; Rolo, M. D.; Stockmanns, T.; Zambanini, A.

    2016-03-01

    The bar PANDA (Antiproton Annihilation at Darmstadt) experiment foresees many detectors for tracking, particle identification and calorimetry. Among them, the innermost is the MVD (Micro Vertex Detector) responsible for a precise tracking and the reconstruction of secondary vertices. This detector will be built from both hybrid pixel (two inner barrels and six forward disks) and double-sided micro strip (two outer barrels and outer rim of the last two disks) silicon sensors. A time-based approach has been chosen for the readout ASIC of the strip sensors. The PASTA (bar PANDA Strip ASIC) chip aims at high resolution time-stamping and charge information through the Time over Threshold (ToT) technique. It benefits from a Time to Digital Converter (TDC) allowing a time bin width down to 50 ps. The analog front-end was designed to serve both n-type and p-type strips and the performed simulations show remarkable performances in terms of linearity and electronic noise. The TDC consists of an analog interpolator, a digital local controller, and a digital global controller as the common back-end for all of the 64 channels.

  9. MicroRNA precursors are not structurally robust but plastic.

    PubMed

    Rodrigo, Guillermo; Elena, Santiago F

    2013-01-01

    Robustness is considered a ubiquitous property of living systems at all levels of organization, and small noncoding RNA (sncRNA) is a genuine model for its study at the molecular level. In this communication, we question whether microRNA precursors (pre-miRNAs) are actually structurally robust, as previously suggested. We found that natural pre-miRNAs are not more robust than expected under an appropriate null model. On the contrary, we found that eukaryotic pre-miRNAs show a significant enrichment in conformational flexibility at the thermal equilibrium of the molecule, that is, in their plasticity. Our results further support the selection for functional diversification and evolvability in sncRNAs.

  10. Micro-structural Fluctuations in 2D Dusty Plasma Liquids

    SciTech Connect

    I Lin; Huang, Y.-H.; Teng, L.-W.

    2007-07-13

    We address structural fluctuations in a cold 2D dusty plasma liquid which is self-organized through the strong Coulomb coupling of the negatively charged micro-meter sized dust particles suspending in weakly ionized discharges. The 2D liquids consist of triangular type ordered domains surrounded by defect clusters, which can be reorganized through avalanche type hopping under the interplay of strong Coulomb coupling and thermal fluctuations. The spatio-temporal evolutions of the local bond-orientational order are directly tracked through digital optical microscopy. The power law scaling of the temporal persistence length of fluctuations is obtained for the cold liquid. The measurement of the conditional probability of the persistence lengths of the successive fluctuating cycles suggests certain types of the persistence length combinations are more preferred. The memory of persistence lasts a few fluctuating cycles.

  11. Micro structuration of gaas surface by wet etching: towards a specific surface behavior.

    PubMed

    Bienaime, Alex; Elie-Caille, Celine; Leblois, Therese

    2012-08-01

    Resonant microelectromechanical systems are promising devices for real time and highly sensitive measurements. The sensitivity of such sensors to additional mass loadings which can be increased thanks to the miniaturisation of devices is of prime importance for biological applications. The miniaturisation of structures passes through a photolithographic process and wet chemical etching. So, this paper presents new results on the anisotropic chemical etching of the gallium arsenide (GaAs) crystal used for this application, in several solutions. This paper focuses on the micro/nanostructuration of the sensing surface to increase the sensor sensitivity. Indeed, this active surface will be biofunctionalized to operate in biological liquid media in view of biomolecules detection. Several experimental conditions of etching bath composition, concentration and temperature were examined to obtain a large variety of geometrical surfaces topographies and roughness. According to the orientation dependence of the chemical etching process, the experiments were also performed on various GaAs crystal plates. The bath 1 H3PO4:9 H2O2:1 H2O appeared to be particularly adapted to the fabrication of the GaAs microstructured membrane: indeed, the bath is highly stable, anisotropic, and, as a function of temperature, it allows the production of a large variety of GaAs surface topographies.

  12. Bio-mimetic optical sensor for structural deflection measurement

    NASA Astrophysics Data System (ADS)

    Frost, Susan A.; Wright, Cameron H. G.; Streeter, Robert W.; Khan, Md. A.; Barrett, Steven F.

    2014-03-01

    Reducing the environmental impact of aviation is a primary goal of NASA aeronautics research. One approach to achieve this goal is to build lighter weight aircraft, which presents complex challenges due to a corresponding increase in structural flexibility. Wing flexibility can adversely affect aircraft performance from the perspective of aerodynamic efficiency and safety. Knowledge of the wing position during flight can aid active control methods designed to mitigate problems due to increased wing flexibility. Current approaches to measuring wing deflection, including strain measurement devices, accelerometers, or GPS solutions, and new technologies such as fiber optic strain sensors, have limitations for their practical application to flexible aircraft control. Hence, it was proposed to use a bio-mimetic optical sensor based on the fly-eye to track wing deflection in real-time. The fly-eye sensor has several advantages over conventional sensors used for this application, including light weight, low power requirements, fast computation, and a small form factor. This paper reports on the fly-eye sensor development and its application to real-time wing deflection measurement.

  13. Optical micro resonance based sensor schemes for detection and identification of nano particles and biological agents in situ

    NASA Astrophysics Data System (ADS)

    Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Schweiger, Gustav; Ostendorf, Andreas

    2010-05-01

    A novel emerging technique for the label-free analysis of nano particles including biomolecules using optical micro cavity resonance is being developed. Various schemes based on a mechanically fixed microspheres as well as microspheres melted by laser on the tip of a standard single mode fiber have been investigated to make further development for microbial application. Water solutions of ethanol, HCl, glucose, vitamin C and biotin have been used to test refractive index changes by monitoring the magnitude of the whispering gallery modes spectral shift. Particular efforts were made for effective fixing of the micro spheres in the water flow, an optimal geometry for micro resonance observation and material of microsphere the most appropriate for microbial application. Optical resonance in free micro spheres from PMMA fixed in micro channels produced by photolithography has been observed under the laser power of less then 1 microwatt. Resonance shifts of C reactive protein water solutions as well as albumin solutions in pure water and with HCl modelling blood have been investigated. Introducing controlled amount of glass gel nano particles into sensor microsphere surrounding were accompanied by both correlative resonance shift (400 nm in diameter) and total reconstruct of resonance spectra (57 nm in diameter). Developed schemes have been demonstrated to be a promising technology platform for sensitive, lab-on-chip type sensor of diagnostic tools for different biological molecules, e.g. proteins, oligonucleotides, oligosaccharides, lipids, small molecules, viral particles, cells as well as in different experimental contexts e.g. proteomics, genomics, drug discovery, and membrane studies.

  14. Active sensors for health monitoring of aging aerospace structures

    SciTech Connect

    GIURGIUTIU,VICTOR; REDMOND,JAMES M.; ROACH,DENNIS P.; RACKOW,KIRK A.

    2000-03-08

    A project to develop non-intrusive active sensors that can be applied on existing aging aerospace structures for monitoring the onset and progress of structural damage (fatigue cracks and corrosion) is presented. The state of the art in active sensors structural health monitoring and damage detection is reviewed. Methods based on (a) elastic wave propagation and (b) electro-mechanical (NM) impedance technique are sighted and briefly discussed. The instrumentation of these specimens with piezoelectric active sensors is illustrated. The main detection strategies (E/M impedance for local area detection and wave propagation for wide area interrogation) are discussed. The signal processing and damage interpretation algorithms are tuned to the specific structural interrogation method used. In the high-frequency EIM impedance approach, pattern recognition methods are used to compare impedance signatures taken at various time intervals and to identify damage presence and progression from the change in these signatures. In the wave propagation approach, the acoustic-ultrasonic methods identifying additional reflection generated from the damage site and changes in transmission velocity and phase are used. Both approaches benefit from the use of artificial intelligence neural networks algorithms that can extract damage features based on a learning process. Design and fabrication of a set of structural specimens representative of aging aerospace structures is presented. Three built-up specimens, (pristine, with cracks, and with corrosion damage) are used. The specimen instrumentation with active sensors fabricated at the University of South Carolina is illustrated. Preliminary results obtained with the E/M impedance method on pristine and cracked specimens are presented.

  15. Active sensors for health monitoring of aging aerospace structures

    SciTech Connect

    GIURGIUTIU,VICTOR; REDMOND,JAMES M.; ROACH,DENNIS P.; RACKOW,KIRK A.

    2000-02-29

    A project to develop non-intrusive active sensors that can be applied on existing aging aerospace structures for monitoring the onset and progress of structural damage (fatigue cracks and corrosion) is presented. The state of the art in active sensors structural health monitoring and damage detection is reviewed. Methods based on (a) elastic wave propagation and (b) electro-mechanical (E/M) impedance technique are cited and briefly discussed. The instrumentation of these specimens with piezoelectric active sensors is illustrated. The main detection strategies (E/M impedance for local area detection and wave propagation for wide area interrogation) are discussed. The signal processing and damage interpretation algorithms are tuned to the specific structural interrogation method used. In the high-frequency E/M impedance approach, pattern recognition methods are used to compare impedance signatures taken at various time intervals and to identify damage presence and progression from the change in these signatures. In the wave propagation approach, the acousto-ultrasonic methods identifying additional reflection generated from the damage site and changes in transmission velocity and phase are used. Both approaches benefit from the use of artificial intelligence neural networks algorithms that can extract damage features based on a learning process. Design and fabrication of a set of structural specimens representative of aging aerospace structures is presented. Three built-up specimens (pristine, with cracks, and with corrosion damage) are used. The specimen instrumentation with active sensors fabricated at the University of South Carolina is illustrated. Preliminary results obtained with the E/M impedance method on pristine and cracked specimens are presented.

  16. Three-dimensional micro-printing of temperature sensors based on up-conversion luminescence

    NASA Astrophysics Data System (ADS)

    Wickberg, Andreas; Mueller, Jonathan B.; Mange, Yatin J.; Fischer, Joachim; Nann, Thomas; Wegener, Martin

    2015-03-01

    The pronounced temperature dependence of up-conversion luminescence from nanoparticles doped with rare-earth elements enables local temperature measurements. By mixing these nanoparticles into a commercially available photoresist containing the low-fluorescence photo-initiator Irgacure 369, and by using three-dimensional direct laser writing, we show that micrometer sized local temperature sensors can be positioned lithographically as desired. Positioning is possible in pre-structured environments, e.g., within buried microfluidic channels or on optical or electronic chips. We use the latter as an example and demonstrate the measurement for both free space and waveguide-coupled excitation and detection. For the free space setting, we achieve a temperature standard deviation of 0.5 K at a time resolution of 1 s.

  17. Three-dimensional micro-printing of temperature sensors based on up-conversion luminescence

    SciTech Connect

    Wickberg, Andreas; Mueller, Jonathan B.; Mange, Yatin J.; Nann, Thomas; Fischer, Joachim; Wegener, Martin

    2015-03-30

    The pronounced temperature dependence of up-conversion luminescence from nanoparticles doped with rare-earth elements enables local temperature measurements. By mixing these nanoparticles into a commercially available photoresist containing the low-fluorescence photo-initiator Irgacure 369, and by using three-dimensional direct laser writing, we show that micrometer sized local temperature sensors can be positioned lithographically as desired. Positioning is possible in pre-structured environments, e.g., within buried microfluidic channels or on optical or electronic chips. We use the latter as an example and demonstrate the measurement for both free space and waveguide-coupled excitation and detection. For the free space setting, we achieve a temperature standard deviation of 0.5 K at a time resolution of 1 s.

  18. Analysis of Piezoelectric Structural Sensors with Emergent Computing Techniques

    NASA Technical Reports Server (NTRS)

    Ramers, Douglas L.

    2005-01-01

    The purpose of this project was to try to interpret the results of some tests that were performed earlier this year and to demonstrate a possible use of emergence in computing to solve IVHM problems. The test data used was collected with piezoelectric sensors to detect mechanical changes in structures. This project team was included of Dr. Doug Ramers and Dr. Abdul Jallob of the Summer Faculty Fellowship Program, Arnaldo Colon-Lopez - a student intern from the University of Puerto Rico of Turabo, and John Lassister and Bob Engberg of the Structural and Dynamics Test Group. The tests were performed by Bob Engberg to compare the performance two types of piezoelectric (piezo) sensors, Pb(Zr(sub 1-1)Ti(sub x))O3, which we will label PZT, and Pb(Zn(sub 1/3)Nb(sub 2/3))O3-PbTiO, which we will label SCP. The tests were conducted under varying temperature and pressure conditions. One set of tests was done by varying water pressure inside an aluminum liner covered with carbon-fiber composite layers (a cylindrical "bottle" with domed ends) and the other by varying temperatures down to cryogenic levels on some specially prepared composite panels. This report discusses the data from the pressure study. The study of the temperature results was not completed in time for this report. The particular sensing done with these piezo sensors is accomplished by the sensor generating an controlled vibration that is transmitted into the structure to which the sensor is attached, and the same sensor then responding to the induced vibration of the structure. There is a relationship between the mechanical impedance of the structure and the resulting electrical impedance produced in the in the piezo sensor. The impedance is also a function of the excitation frequency. Changes in the real part of impendance signature relative to an original reference signature indicate a change in the coupled structure that could be the results of damage or strain. The water pressure tests were conducted by

  19. A wireless MEMS-based inclinometer sensor node for structural health monitoring.

    PubMed

    Ha, Dae Woong; Park, Hyo Seon; Choi, Se Woon; Kim, Yousok

    2013-11-26

    This paper proposes a wireless inclinometer sensor node for structural health monitoring (SHM) that can be applied to civil engineering and building structures subjected to various loadings. The inclinometer used in this study employs a method for calculating the tilt based on the difference between the static acceleration and the acceleration due to gravity, using a micro-electro-mechanical system (MEMS)-based accelerometer. A wireless sensor node was developed through which tilt measurement data are wirelessly transmitted to a monitoring server. This node consists of a slave node that uses a short-distance wireless communication system (RF 2.4 GHz) and a master node that uses a long-distance telecommunication system (code division multiple access-CDMA). The communication distance limitation, which is recognized as an important issue in wireless monitoring systems, has been resolved via these two wireless communication components. The reliability of the proposed wireless inclinometer sensor node was verified experimentally by comparing the values measured by the inclinometer and subsequently transferred to the monitoring server via wired and wireless transfer methods to permit a performance evaluation of the wireless communication sensor nodes. The experimental results indicated that the two systems (wired and wireless transfer systems) yielded almost identical values at a tilt angle greater than 1°, and a uniform difference was observed at a tilt angle less than 0.42° (approximately 0.0032° corresponding to 0.76% of the tilt angle, 0.42°) regardless of the tilt size. This result was deemed to be within the allowable range of measurement error in SHM. Thus, the wireless transfer system proposed in this study was experimentally verified for practical application in a structural health monitoring system.

  20. A Wireless MEMS-Based Inclinometer Sensor Node for Structural Health Monitoring

    PubMed Central

    Ha, Dae Woong; Park, Hyo Seon; Choi, Se Woon; Kim, Yousok

    2013-01-01

    This paper proposes a wireless inclinometer sensor node for structural health monitoring (SHM) that can be applied to civil engineering and building structures subjected to various loadings. The inclinometer used in this study employs a method for calculating the tilt based on the difference between the static acceleration and the acceleration due to gravity, using a micro-electro-mechanical system (MEMS)-based accelerometer. A wireless sensor node was developed through which tilt measurement data are wirelessly transmitted to a monitoring server. This node consists of a slave node that uses a short-distance wireless communication system (RF 2.4 GHz) and a master node that uses a long-distance telecommunication system (code division multiple access—CDMA). The communication distance limitation, which is recognized as an important issue in wireless monitoring systems, has been resolved via these two wireless communication components. The reliability of the proposed wireless inclinometer sensor node was verified experimentally by comparing the values measured by the inclinometer and subsequently transferred to the monitoring server via wired and wireless transfer methods to permit a performance evaluation of the wireless communication sensor nodes. The experimental results indicated that the two systems (wired and wireless transfer systems) yielded almost identical values at a tilt angle greater than 1°, and a uniform difference was observed at a tilt angle less than 0.42° (approximately 0.0032° corresponding to 0.76% of the tilt angle, 0.42°) regardless of the tilt size. This result was deemed to be within the allowable range of measurement error in SHM. Thus, the wireless transfer system proposed in this study was experimentally verified for practical application in a structural health monitoring system. PMID:24287533

  1. Sensor-based diagnosis using knowledge of structure and function

    NASA Technical Reports Server (NTRS)

    Scarl, Ethan A.; Jamieson, John R.; Delaune, Carl I.

    1987-01-01

    A system for fault detection and isolation called LES, developed at the Kennedy Space Center for the Space Shuttle's Launch Processing System, is a well-developed diagnostic system that is simultaneously model-based and sensor-based. This experiment has led to a surprising result: the failure of a sensor can not only be handled in precisely the same way as the failure of any other object, but may present an especially easy case. Classical rule-based diagnostic systems need to find out whether or not their sensors are telling them the truth before they can safely draw inferences from them. By contrast, while LES does treat sensors as a special case, it does so only because there may exist a short cut that allows them to be handled more simply than other objects. LES uses both structural and functional knowledge, and has found cases in which the structural knowledge can be economically replaced by the judicious use of functional relationships; LES' functional relationships are stored in exactly one place, so they must be inverted to determine hypothetical values for possibly faulty objects. The inversion process has been extended to include conditional functions not normally considered to have inverses.

  2. Micro-miniature autonomous optical sensor array for monitoring ions and metabolites 1: design, fabrication, and data analysis.

    PubMed

    Tohda, Koji; Gratzl, Miklós

    2006-03-01

    A micro-miniature array of sensing capsules for optical monitoring of pH, potassium and glucose is described. Optode technology translates the respective ionic levels into variable colors of ionophore/dye/polymeric liquid micro-beads stuffed into individual capsules. Glucose is monitored indirectly, by coupling through glucose oxidase (GOX) immobilized in cellulose acetate phthalate (CAP) based microscopic beads that are stuffed into another microcapsule together with pH sensitive optical microscopic beads. The electrolyte and glucose sensing capsules are embedded in a transparent cellulose acetate bar 300-500 microm wide and 2-2.5 mm long called the sliver sensor that includes also a white capsule made of micro-beads without dye for optical reference. By adding further capsules custom combinations of analytes can be monitored in biomedical and non-biological contexts. In this work, as an example, design, fabrication and testing of a sliver sensor that could be developed for in vivo use are described.

  3. Active structural acoustic control using the remote sensor method

    NASA Astrophysics Data System (ADS)

    Cheer, Jordan; Daley, Steve

    2016-09-01

    Active structural acoustic control (ASAC) is an effective method of reducing the sound radiation from vibrating structures. In order to implement ASAC systems using only structural actuators and sensors, it is necessary to employ a model of the sound radiation from the structure. Such models have been presented in the literature for simple structures, such as baffled rectangular plates, and methods of determining the radiation modes of more complex practical structures using experimental data have also been explored. A similar problem arises in the context of active noise control, where cancellation of a disturbance is required at positions in space where it is not possible to locate a physical error microphone. In this case the signals at the cancellation points can be estimated from the outputs of remotely located measurement sensors using the “remote microphone method”. This remote microphone method is extended here to the ASAC problem, in which the pressures at a number of microphone locations must be estimated from measurements on the structure of the radiating system. The control and estimation strategies are described and the performance is assessed for a typical structural radiation problem.

  4. Construction of micro-nano network structure on titanium surface for improving bioactivity

    NASA Astrophysics Data System (ADS)

    Jiang, Pinliang; Liang, Jianhe; Lin, Changjian

    2013-09-01

    A novel hierarchical micro-nano structured titania layer was constructed on Ti surface to mimic the multi-level bone structure. The Ti substrate was subjected to a suitable acid etching and subsequent anodization in NaOH electrolyte to form a micro-nano porous titania layer. It was indicated that this microporous/nano-network (micro/nano-network) structured surface presented the enhanced wettability and superhydrophilic property. The polarization curve measurements showed that the as-prepared micro/nano-network structured TiO2 surface was of better corrosion resistance compared to the blank Ti surface, according to its corrosion current decreased, corrosion potential shifted positively and polarization resistance increased in Hank's solution. Meanwhile, the Mott-Schottky plots revealed that less oxygen vacancies existed in the micro/nano-network structured TiO2 film in contrast to the natural oxide film on blank Ti surface. Moreover, it was observed that the micro/nano-network structured surface was completely covered by a homogeneous apatite layer when immersed in simulated body fluid (SBF) for 14 days, exhibiting an excellent ability of biomineration. Furthermore, the superior cell adhesion and viability were discerned on such hierarchically structured surface, through a comparison of MG63 cell behaviors on blank Ti surface, nano-network structured surface and micro/nano-network structured surface. All results suggest our construction of micro-nano porous TiO2 surface is a promising strategy for improving the bioactivity of titanium implants.

  5. New developments in the manufacture of large freeform surfaces with micro-structures

    NASA Astrophysics Data System (ADS)

    Roblee, Jeff; Walter, Mark; Jacobs, Ben

    2015-10-01

    A new capability for simultaneously generating micro-structures and large freeform surfaces has been developed. Multiple axes of CNC coordinated motion have been integrated into an ultra precision machine platform, enabling a wide variety of optical mold masters to be created. Facilitated by a specially developed control system, freeform optical surfaces as large as 600 x 600 x 100 mm are possible. Some machine alignments are critical to the production of accurate parts and these will be discussed. A bridge construction reduces Abbe offsets, and oil hydrostatic linear slide ways provide sub-micron straightness. The linear axes are capable of accurate positioning by means of linear motors in combination with the non contact oil hydrostatic slide ways. Optical surface finishes are achieved with the stability of a large granite base supported by a high performance vibration isolation system. The machine includes a unique, self-compensating, patented oil bearing rotary axis. Critical machine errors are measured and corrected with integrated CNC machine compensation. The machine has accuracy and repeatability for the creation of precise, intersecting groove structures with multiple angles over large areas. Optical surfaces can be generated either by a ruling/shaping operation with a non-rotating tool, or by a flycutting tool rotating on a high speed air bearing spindle. The spindle can double as a positioning axis to generate variable angle grooves in ruling mode. A Fast Tool Servo can be utilized to create fine micro-structures. Work piece quality can be evaluated in-situ with metrology sensors.

  6. Spherical silica micro/nanomaterials with hierarchical structures: synthesis and applications.

    PubMed

    Du, Xin; He, Junhui

    2011-10-05

    This paper reviews the progress made recently in synthesis and applications of spherical silica micro/nanomaterials with multilevel (hierarchical) structures. The spherical silica micro/nanomaterials with hierarchical structures are classified into four main structural categories that include (1) hollow mesoporous spheres, (2) core-in-(hollow porous shell) spheres, (3) hollow spheres with multiple porous shells and (4) hierarchically porous spheres. Due to the complex structures and being focused on spherical silica micro/nanomaterials, some novel methods based on the combination of two routine methods or two surfactants, and some special synthetic strategies are proposed to produce the spherical silica micro/nanomaterials with hierarchical structures. Compared with the same-sized solid, porous or hollow silica spheres, these fantastic spherical silica micro/nanomaterials with hierarchical structures exhibit enhanced properties which may enable them to be used in broad and promising applications as ideal scaffolds (carriers) for biological, medical, and catalytic applications.

  7. Hybrid optical-fibre/geopolymer sensors for structural health monitoring of concrete structures

    NASA Astrophysics Data System (ADS)

    Perry, M.; Saafi, M.; Fusiek, G.; Niewczas, P.

    2015-04-01

    In this work, we demonstrate hybrid optical-fibre/geopolymer sensors for monitoring temperature, uniaxial strain and biaxial strain in concrete structures. The hybrid sensors detect these measurands via changes in geopolymer electrical impedance, and via optical wavelength measurements of embedded fibre Bragg gratings. Electrical and optical measurements were both facilitated by metal-coated optical fibres, which provided the hybrid sensors with a single, shared physical path for both voltage and wavelength signals. The embedded fibre sensors revealed that geopolymer specimens undergo 2.7 mɛ of shrinkage after one week of curing at 42 °C. After curing, an axial 2 mɛ compression of the uniaxial hybrid sensor led to impedance and wavelength shifts of 7 × 10-2 and -2 × 10-4 respectively. The typical strain resolution in the uniaxial sensor was 100 μ \\varepsilon . The biaxial sensor was applied to the side of a concrete cylinder, which was then placed under 0.6 mɛ of axial, compressive strain. Fractional shifts in impedance and wavelength, used to monitor axial and circumferential strain, were 3 × 10-2 and 4 × 10-5 respectively. The biaxial sensor’s strain resolution was approximately 10 μ \\varepsilon in both directions. Due to several design flaws, the uniaxial hybrid sensor was unable to accurately measure ambient temperature changes. The biaxial sensor, however, successfully monitored local temperature changes with 0.5 °C resolution.

  8. Micro-structured PDMS piezoelectric enhancement through charging conditions

    NASA Astrophysics Data System (ADS)

    Kachroudi, Achraf; Basrour, Skandar; Rufer, Libor; Sylvestre, Alain; Jomni, Fathi

    2016-10-01

    Micro-structured cellular polydimethylsiloxane (PDMS) materials were prepared by a low-cost molding process allowing us to control geometry and sample size. Cellular structures are charged with a triangular quasi-static voltage with amplitudes between 1 kV and 4 kV and a frequency of 0.5 Hz fixed after having evaluated the conditions enhancing the piezoelectric response of the cellular PDMS. The piezo-electret PDMS material charged at room temperature has a piezoelectric coefficient d 33 of 350 pC/N, which is ten times larger than that of polyvinylidene fluoride. The high piezoelectric coefficient with a very low elastic modulus of 300 kPa makes these materials very useful for wearable device applications. The piezoelectric coefficient d 33 of the samples poled at high temperatures improves thermal stability but reduces PDMS piezo-electret piezoelectricity, which is explained by the structure’s stiffness. These results are useful and allow us to set the conditions for the preparation of the piezo-electret materials according to desired applications.

  9. Pipelining in structural health monitoring wireless sensor network

    NASA Astrophysics Data System (ADS)

    Li, Xu; Dorvash, Siavash; Cheng, Liang; Pakzad, Shamim

    2010-04-01

    Application of wireless sensor network (WSN) for structural health monitoring (SHM), is becoming widespread due to its implementation ease and economic advantage over traditional sensor networks. Beside advantages that have made wireless network preferable, there are some concerns regarding their performance in some applications. In long-span Bridge monitoring the need to transfer data over long distance causes some challenges in design of WSN platforms. Due to the geometry of bridge structures, using multi-hop data transfer between remote nodes and base station is essential. This paper focuses on the performances of pipelining algorithms. We summarize several prevent pipelining approaches, discuss their performances, and propose a new pipelining algorithm, which gives consideration to both boosting of channel usage and the simplicity in deployment.

  10. Impact load-induced micro-structural damage and micro-structure associated mechanical response of concrete made with different surface roughness and porosity aggregates

    SciTech Connect

    Erdem, Savas Dawson, Andrew Robert; Thom, Nicholas Howard

    2012-02-15

    The relationship between the nature of micro damage under impact loading and changes in mechanical behavior associated with different microstructures is studied for concretes made with two different coarse aggregates having significant differences mainly in roughness and porosity - sintered fly ash and uncrushed gravel. A range of techniques including X-ray diffraction, digital image analysis, mercury porosimetry, X-ray computed tomography, laser surface profilometry and scanning electron microscopy were used to characterize the aggregates and micro-structures. The concrete prepared with lightweight aggregates was stronger in compression than the gravel aggregate concrete due to enhanced hydration as a result of internal curing. In the lightweight concrete, it was deduced that an inhomogeneous micro-structure led to strain incompatibilities and consequent localized stress concentrations in the mix, leading to accelerated failure. The pore structure, compressibility, and surface texture of the aggregates are of paramount importance for the micro-cracking growth.

  11. Sensor failure detection using generalized parity relations for flexible structures

    NASA Technical Reports Server (NTRS)

    Mercadal, Mathieu

    1989-01-01

    Analytical redundancy may be preferable to hardware redundancy in failure detection/isolation tasks for such large-scale systems as space structures. Generalized single-sensor parity relations are presently applied to this problem; they are noted to yield a very simple isolation logic, and their generation is found to be extremely rapid, even in the case of extremely complex systems, provided only that the eigenstructure of the system be known. Their implementation is, however, extremely sensitive to modeling errors and noise.

  12. Experimental and numerical investigation into micro-flow cytometer with 3-D hydrodynamic focusing effect and micro-weir structure.

    PubMed

    Hou, Hui-Hsiung; Tsai, Chien-Hsiung; Fu, Lung-Ming; Yang, Ruey-Jen

    2009-07-01

    This study presents a novel 3-D hydrodynamic focusing technique for micro-flow cytometers. In the proposed approach, the sample stream is compressed initially in the horizontal direction by a set of sheath flows such that it is constrained to the central region of the microchannel and is then focused in the vertical direction by a second pair of sheath flows. Thereafter, the focused sample stream passes over a micro-weir structure positioned directly beneath an optical detection system to capture polystyrene beads fluorescent signal. The microchannel configuration and operational parameters are optimized by performing a series of numerical simulations. An experimental investigation is then performed using a micro-flow cytometer fabricated using conventional micro-electro-mechanical systems techniques and an isotropic wet etching method. The results indicate that the two sets of sheath flows successfully constrain the sample stream within a narrow, well-defined region of the microchannel. Furthermore, the micro-weir structure prompts the separation of a mixed sample of 5 and 10 microm polystyrene beads in the vertical direction and ensures that the beads flow through the detection region of the microchannel in a sequential fashion and can therefore be reliably detected and counted.

  13. Developing a robust wireless sensor network structure for environmental sensing

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Oroza, C.; Glaser, S. D.; Bales, R. C.; Conklin, M. H.

    2013-12-01

    The American River Hydrologic Observatory is being strategically deployed as a real-time ground-based measurement network that delivers accurate and timely information on snow conditions and other hydrologic attributes with a previously unheard of granularity of time and space. The basin-scale network involves 18 sub-networks set out at physiographically representative locations spanning the seasonally snow-covered half of the 5000 km2 American river basin. Each sub-network, covering about a 1-km2 area, consists of 10 wirelessly networked sensing nodes that continuously measure and telemeter temperature, and snow depth; plus selected locations are equipped with sensors for relative humidity, solar radiation, and soil moisture at several depths. The sensor locations were chosen to maximize the variance sampled for snow depth within the basin. Network design and deployment involves an iterative but efficient process. After sensor-station locations are determined, a robust network of interlinking sensor stations and signal repeaters must be constructed to route sensor data to a central base station with a two-way communicable data uplink. Data can then be uploaded from site to remote servers in real time through satellite and cell modems. Signal repeaters are placed for robustness of a self-healing network with redundant signal paths to the base station. Manual, trial-and-error heuristic approaches for node placement are inefficient and labor intensive. In that approach field personnel must restructure the network in real time and wait for new network statistics to be calculated at the base station before finalizing a placement, acting without knowledge of the global topography or overall network structure. We show how digital elevation plus high-definition aerial photographs to give foliage coverage can optimize planning of signal repeater placements and guarantee a robust network structure prior to the physical deployment. We can also 'stress test' the final network

  14. Investigating the performance of catalyst layer micro-structures with different platinum loadings

    SciTech Connect

    Khakaz-Baboli, Moben; Harvey, David; Pharoah, Jon

    2012-07-01

    In this study a four-phase micro-structure of a PEFC catalyst layer was reconstructed by randomly placing overlapping spheres for each solid catalyst phase. The micro-structure was mirrored to make a micro-structure. A body-fit computational mesh was produced for the reconstructed micro-structure in OpenFOAM. Associated conservation equations were solved within all the phases with electrochemical reaction as the boundary condition at the interface between ionomer and platinum phases. The study is focused on the platinum loading of CL. The polarization curves of the micro-structure performance have been compared for different platinum loadings. This paper gives increased insight into the relatively greater losses at decreased platinum loadings.

  15. Hemocompatibility research on the micro-structure surface of a bionic heart valve.

    PubMed

    Ye, Xia; Wang, Ze; Zhang, Xianghua; Zhou, Ming; Cai, Lan

    2014-01-01

    In order to study how the geometric parameters and shape of the micro-structure surface of a bionic heart valve affects hemocompatibility, mastoid micro-structures with different periodic space were fabricated using a femtosecond laser on a polyurethane (PU) surface. The apparent contact angles of droplets on the micro-structure surfaces were measured to characterize their wettability. Then a series of blood compatibility experiments, including platelet adhesion, dynamic coagulation and hemolysis were completed. The experimental results showed that the micro-structure on the biomaterial surface helped improve its hydrophobicity and hemocompatibility. Also, the periodic space affected not only the hydrophobicity but also the hemocompatibility of the biomaterial. With the increasing of the periodic space, the apparent contact angle increased, the number of platelet adhesion decreased, the dynamic clotting time became longer and the hemolysis ratio reduced. In addition, the shape of the micro-structure also affected the hemocompatibility of the biomaterial.

  16. microRNAs Databases: Developmental Methodologies, Structural and Functional Annotations.

    PubMed

    Singh, Nagendra Kumar

    2016-03-28

    microRNA (miRNA) is an endogenous and evolutionary conserved non-coding RNA, involved in post-transcriptional process as gene repressor and mRNA cleavage through RNA-induced silencing complex (RISC) formation. In RISC, miRNA binds in complementary base pair with targeted mRNA along with Argonaut proteins complex, causes gene repression or endonucleolytic cleavage of mRNAs and results in many diseases and syndromes. After the discovery of miRNA lin-4 and let-7, subsequently large numbers of miRNAs were discovered by low-throughput and high-throughput experimental techniques along with computational process in various biological and metabolic processes. The miRNAs are important non-coding RNA for understanding the complex biological phenomena of organism because it controls the gene regulation. This paper reviews miRNA databases with structural and functional annotations developed by various researchers. These databases contain structural and functional information of animal, plant and virus miRNAs including miRNAs-associated diseases, stress resistance in plant, miRNAs take part in various biological processes, effect of miRNAs interaction on drugs and environment, effect of variance on miRNAs, miRNAs gene expression analysis, sequence of miRNAs, structure of miRNAs. This review focuses on the developmental methodology of miRNA databases such as computational tools and methods used for extraction of miRNAs annotation from different resources or through experiment. This study also discusses the efficiency of user interface design of every database along with current entry and annotations of miRNA (pathways, gene ontology, disease ontology, etc.). Here, an integrated schematic diagram of construction process for databases is also drawn along with tabular and graphical comparison of various types of entries in different databases. Aim of this paper is to present the importance of miRNAs-related resources at a single place.

  17. Fabrication and characterization of 3C-silicon carbide micro sensor for wireless blood pressure measurements

    NASA Astrophysics Data System (ADS)

    Basak, Nupur

    A potentially implantable single crystal 3C-SiC pressure sensor for blood pressure measurement was designed, simulated, fabricated, characterized and optimized. This research uses a single crystal 3C-SiC, for the first time, to demonstrate its application as a blood pressure measurement sensor. The sensor, which uses the epitaxial grown 3C-SiC membrane to measure changes in pressure, is designed to be wireless, biocompatible and linear. The SiC material was chosen for its superior physical, chemical and mechanical properties; the capacitive sensor uses a 3C-SiC membrane as one of the electrodes; and, the sensor system is wireless for comfort and to allow for convenient reading of real-time pressure data (wireless communication is enabled by connecting the sensor parallel to a planar inductor). Together, the variable capacitive sensor and planar inductor create a pressure sensitive resonant circuit. The sensor system described above allows for implantation into a human patient's body, after which the planar inductor can be coupled with an external inductor to receive data for real-time blood pressure measurement. Electroplating, thick photo-resist characterization, RIE etching, oxidation, CVD, chemical mechanical polishing and wafer bonding were optimized during the process of fabricating the sensor system and, in addition to detailing the sensor system simulation and characterization; the optimized processes are detailed in the dissertation. This absolute pressure sensor is designed to function optimally within the human blood pressure range of 50-350mmHg. The layout and modeling of the sensor uses finite element analysis (FEA) software. The simulations for membrane deflection, stress analysis and electro-mechanical analysis are performed for 100 μm2 and 400μm2sensors. The membrane deflection-pressure, capacitance-pressure and resonant frequency-pressure graphs were obtained, and detailed in the dissertation, along with the planar inductor simulation for

  18. Fly-ear inspired micro-sensor for sound source localization in two dimensions.

    PubMed

    Lisiewski, A P; Liu, H J; Yu, M; Currano, L; Gee, D

    2011-05-01

    Inspired by the hearing organ of the fly Ormia ochracea, a miniature sound localization sensor is developed, which can be used to pinpoint a sound source in two dimensions described by the azimuth and elevation angles. The sensor device employs an equilateral triangle configuration consisting of three mechanically coupled circular membranes whose oscillations are detected by a fiber-optic system. The experimental results indicate that significant amplification of the directional cues and directional sensitivity can be achieved with the fly-ear inspired sensor design. This work can provide a basis for the development of miniature sound localization sensors in two dimensions.

  19. Structural monitoring by curvature analysis using interferometric fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Inaudi, D.; Vurpillot, S.; Casanova, N.; Kronenberg, P.

    1998-04-01

    All structures undergo deformations under the effects of loads or degradation of the constituent materials. The deformations of any structure (bridges, dams, frames, shells, tunnels, towers, wings, trusses,0964-1726/7/2/007/img9) contain a lot of information about its health state. By measuring these deformations it is possible to analyse the loading and aging behavior of the structure. The presented method analyses a structure by subdividing it into sections and cells. The deformation of each of these macro-elements is first analysed separately to obtain local information about the materials, and then combined to provide insight on the global behavior. Examples of these techniques applied to civil engineering structures fitted with long-gage-length fiber optic sensors show the variety of information that can be obtained using this powerful analysis technique.

  20. Optical characterization of MEMS micro-mirror arrays using digital holographic Shack-Hartmann wavefront sensor: a new technique

    NASA Astrophysics Data System (ADS)

    Anisimov, Igor; Dooley, Sarah B.

    2011-05-01

    Micro-Electro-Mechanical Systems (MEMS) Micro-Mirror Arrays (MMAs) are widely used in advanced laser beam steering systems and as adaptive optical elements. The new generation of MEMS MMAs are fabricated by bulk micromachining of a single Silicon-On-Insulator wafer. Optical characterization of MEMS MMAs can be done by direct detection of the reflected beams or by using more advanced wavefront measuring techniques, such as a phase-shifting interferometer or Shack-Hartmann wavefront sensor. In the case of an interferometer, the geometry of the tested MMA can be calculated after performing the phase unwrapping procedure, which can be quite complex. In the latter case of the Shack-Hartmann wavefront sensor, careful selection of a highquality array of microlenses is required in order to match the capabilities of the wavefront sensor to the measured wavefront produced by the MMA. The presented digital Shack-Hartmann technique is a modified approach for wavefront characterization based on digital processing of the interferometer data. The optical wavefront from the tested MMA is mixed with the reference wavefront. Then the recorded interference intensity image is Fourier transformed producing digitally synthesized images of the optical beams in the far field. Therefore, the digital version of the Shack-Hartmann wavefront sensor does not require the use of an array of microlenses and is primarily limited by the detector array geometry. One can digitally generate any configuration of subapertures corresponding to various geometries of microlenses. However, this new technique does require coherent optical mixing of the two wavefronts in order to produce the interference pattern.

  1. A sensitive optical micro-machined ultrasound sensor (OMUS) based on a silicon photonic ring resonator on an acoustical membrane.

    PubMed

    Leinders, S M; Westerveld, W J; Pozo, J; van Neer, P L M J; Snyder, B; O'Brien, P; Urbach, H P; de Jong, N; Verweij, M D

    2015-09-22

    With the increasing use of ultrasonography, especially in medical imaging, novel fabrication techniques together with novel sensor designs are needed to meet the requirements for future applications like three-dimensional intercardiac and intravascular imaging. These applications require arrays of many small elements to selectively record the sound waves coming from a certain direction. Here we present proof of concept of an optical micro-machined ultrasound sensor (OMUS) fabricated with a semi-industrial CMOS fabrication line. The sensor is based on integrated photonics, which allows for elements with small spatial footprint. We demonstrate that the first prototype is already capable of detecting pressures of 0.4 Pa, which matches the performance of the state of the art piezo-electric transducers while having a 65 times smaller spatial footprint. The sensor is compatible with MRI due to the lack of electronical wiring. Another important benefit of the use of integrated photonics is the easy interrogation of an array of elements. Hence, in future designs only two optical fibers are needed to interrogate an entire array, which minimizes the amount of connections of smart catheters. The demonstrated OMUS has potential applications in medical ultrasound imaging, non destructive testing as well as in flow sensing.

  2. A sensitive optical micro-machined ultrasound sensor (OMUS) based on a silicon photonic ring resonator on an acoustical membrane

    PubMed Central

    Leinders, S.M.; Westerveld, W.J.; Pozo, J.; van Neer, P.L.M.J.; Snyder, B.; O’Brien, P.; Urbach, H.P.; de Jong, N.; Verweij, M.D.

    2015-01-01

    With the increasing use of ultrasonography, especially in medical imaging, novel fabrication techniques together with novel sensor designs are needed to meet the requirements for future applications like three-dimensional intercardiac and intravascular imaging. These applications require arrays of many small elements to selectively record the sound waves coming from a certain direction. Here we present proof of concept of an optical micro-machined ultrasound sensor (OMUS) fabricated with a semi-industrial CMOS fabrication line. The sensor is based on integrated photonics, which allows for elements with small spatial footprint. We demonstrate that the first prototype is already capable of detecting pressures of 0.4 Pa, which matches the performance of the state of the art piezo-electric transducers while having a 65 times smaller spatial footprint. The sensor is compatible with MRI due to the lack of electronical wiring. Another important benefit of the use of integrated photonics is the easy interrogation of an array of elements. Hence, in future designs only two optical fibers are needed to interrogate an entire array, which minimizes the amount of connections of smart catheters. The demonstrated OMUS has potential applications in medical ultrasound imaging, non destructive testing as well as in flow sensing. PMID:26392386

  3. Research and Development on In-Situ Measurement Sensors for Micro-Meteoroid and Small Space Debris at JAXA

    NASA Astrophysics Data System (ADS)

    Kitazawa, Y.; Matsumoto, H.; Okudaira, O.; Kimoto, Y.; Hanada, T.; Faure, P.; Akahoshi, Y.; Hattori, M.; Karaki, A.; Sakurai, A.; Funakoshi, K.; Yasaka, T.

    2013-08-01

    The Japan Aerospace Exploration Agency (JAXA) has been conducting R&D into in-situ sensors for measuring micro-meteoroid and small-sized debris (MMSD) since the 1980s. Research into active sensors started with the meteoroid observation experiment conducted using the HITEN (MUSES-A) satellite that ISAS/JAXA launched in 1990. The main purpose behind the start of passive collector research was SOCCER, a late-80s Japan-US mission that was designed to capture cometary dust and then return to the Earth. Although this mission was cancelled, the research outcomes were employed in a JAXA mission for the return of MMSD samples using calibrated aerogel and involving the space shuttle and the International Space Station. Many other important activities have been undertaken as well, and the knowledge they have generated has contributed to JAXA's development of a new type of active dust sensor. This paper reports on the R&D conducted at JAXA into in-situ MMSD measurement sensors.

  4. Study on the structure of bridge surface of the micro Fabry-Perot cavity tunable filter

    NASA Astrophysics Data System (ADS)

    Meng, Qinghua; Luo, Huan; Bao, Shiwei; Zhou, Yifan; Chen, Sihai

    2011-02-01

    Micro Fabry-Perot cavity tunable filters are widely applied in the area of Pushbroom Hyperspectral imaging, DWDM optical communication system and self-adaptive optics. With small volume, lower consumption and cost, the Micro Fabry-Perot cavity tunable filter can realize superior response speed, large spectral range, high definition and high reliability. By deposition metal membrane on silicon chip by MEMS technology, the micro Fabry-Perot cavity has been achieved, which is actuated by electrostatic force and can realize the function of an optical filter. In this paper, the micro-bridge structure of the micro Fabry-Perot cavity tunable filter has been studied. Finite element analysis software COMSOL Multiphysics has been adopted to design the structure of the micro-bridge of the micro filter. In order to simulate the working mechanism of the micro Fabry-Perot cavity and study the electrical and mechanical characteristics of the micro tunable filter,the static and dynamic characteriastics are analyzed, such as stress, displacement, transient response, etc. The corresponding parameters of the structure are considered as well by optimizition the filter's sustain structure.

  5. Midwave Infrared (2-6{micro}m) Emitter-Based Chemical Sensor Systems

    SciTech Connect

    Allerman, A.A.; Biefeld, R.M.; Kurtz, S.R.

    1999-02-01

    Long wavelength (2-6 {micro}m) diode emitters are desirable for many applications including monitoring of chemical species in the environment and manufacturing, long wavelength fiber-optic communications, lidar, and JR detector counter-measures. No practical diode lasers are available for any of these applications because the band structure of bulk III-V, II-VI, and IV-VI semiconductor alloys results in large Auger recombination rates at these wavelengths. Experimental and theoretical work at Sandia has resulted in new understanding of the electronic properties of narrow bandgap III-V heterostructures, and we have found methods of reducing the Auger rates in certain InAsSb superlattices and quantum wells. These devices enable us to begin chemical sensing demonstrations of important species such as CO-CO{sub 2} and numerous other compounds. This project will involve developing chemical sensing systems and determining the sensitivity and limitations of these systems. Concurrently, we will improve upon infrared emitters used in these systems.

  6. Rapid Characterization of Vegetation Structure with a Microsoft Kinect Sensor

    PubMed Central

    Azzari, George; Goulden, Michael L.; Rusu, Radu B.

    2013-01-01

    The importance of vegetation structure and biomass in controlling land-atmosphere exchange is widely recognized, but measurements of canopy structure are challenging, time consuming, and often rely on destructive methods. The Microsoft Kinect is an infrared sensor designed for video gaming that outputs synchronized color and depth images and that has the potential to allow rapid characterization of vegetation structure. We compared depth images from a Kinect sensor with manual measurements of plant structure and size for two species growing in a California grassland. The depth images agreed well with the horizontal and vertical measurements of plant size made manually. Similarly, the plant volumes calculated with a three-dimensional convex hulls approach was well related to plant biomass. The Kinect showed some limitations for ecological observation associated with a short measurement range and daytime light contamination. Nonetheless, the Kinect's light weight, fast acquisition time, low power requirement, and cost make it a promising tool for rapid field surveys of canopy structure, especially in small-statured vegetation. PMID:23435053

  7. Rapid characterization of vegetation structure with a Microsoft Kinect sensor.

    PubMed

    Azzari, George; Goulden, Michael L; Rusu, Radu B

    2013-02-11

    The importance of vegetation structure and biomass in controlling land-atmosphere exchange is widely recognized, but measurements of canopy structure are challenging, time consuming, and often rely on destructive methods. The Microsoft Kinect is an infrared sensor designed for video gaming that outputs synchronized color and depth images and that has the potential to allow rapid characterization of vegetation structure. We compared depth images from a Kinect sensor with manual measurements of plant structure and size for two species growing in a California grassland. The depth images agreed well with the horizontal and vertical measurements of plant size made manually. Similarly, the plant volumes calculated with a three-dimensional convex hulls approach was well related to plant biomass. The Kinect showed some limitations for ecological observation associated with a short measurement range and daytime light contamination. Nonetheless, the Kinect's light weight, fast acquisition time, low power requirement, and cost make it a promising tool for rapid field surveys of canopy structure, especially in small-statured vegetation.

  8. A hierarchical structure approach to MultiSensor Information Fusion

    SciTech Connect

    Maren, A.J. . Space Inst.); Pap, R.M.; Harston, C.T. )

    1989-01-01

    A major problem with image-based MultiSensor Information Fusion (MSIF) is establishing the level of processing at which information should be fused. Current methodologies, whether based on fusion at the pixel, segment/feature, or symbolic levels, are each inadequate for robust MSIF. Pixel-level fusion has problems with coregistration of the images or data. Attempts to fuse information using the features of segmented images or data relies an a presumed similarity between the segmentation characteristics of each image or data stream. Symbolic-level fusion requires too much advance processing to be useful, as we have seen in automatic target recognition tasks. Image-based MSIF systems need to operate in real-time, must perform fusion using a variety of sensor types, and should be effective across a wide range of operating conditions or deployment environments. We address this problem through developing a new representation level which facilitates matching and information fusion. The Hierarchical Scene Structure (HSS) representation, created using a multilayer, cooperative/competitive neural network, meets this need. The MSS is intermediate between a pixel-based representation and a scene interpretation representation, and represents the perceptual organization of an image. Fused HSSs will incorporate information from multiple sensors. Their knowledge-rich structure aids top-down scene interpretation via both model matching and knowledge-based,region interpretation.

  9. A hierarchical structure approach to MultiSensor Information Fusion

    SciTech Connect

    Maren, A.J.; Pap, R.M.; Harston, C.T.

    1989-12-31

    A major problem with image-based MultiSensor Information Fusion (MSIF) is establishing the level of processing at which information should be fused. Current methodologies, whether based on fusion at the pixel, segment/feature, or symbolic levels, are each inadequate for robust MSIF. Pixel-level fusion has problems with coregistration of the images or data. Attempts to fuse information using the features of segmented images or data relies an a presumed similarity between the segmentation characteristics of each image or data stream. Symbolic-level fusion requires too much advance processing to be useful, as we have seen in automatic target recognition tasks. Image-based MSIF systems need to operate in real-time, must perform fusion using a variety of sensor types, and should be effective across a wide range of operating conditions or deployment environments. We address this problem through developing a new representation level which facilitates matching and information fusion. The Hierarchical Scene Structure (HSS) representation, created using a multilayer, cooperative/competitive neural network, meets this need. The MSS is intermediate between a pixel-based representation and a scene interpretation representation, and represents the perceptual organization of an image. Fused HSSs will incorporate information from multiple sensors. Their knowledge-rich structure aids top-down scene interpretation via both model matching and knowledge-based,region interpretation.

  10. Micro-patterning and characterization of PHEMA-co-PAM-based optical chemical sensors for lab-on-a-chip applications

    PubMed Central

    Zhu, Haixin; Zhou, Xianfeng; Su, Fengyu; Tian, Yanqing; Ashili, Shashanka; Holl, Mark R.; Meldrum, Deirdre R.

    2012-01-01

    We report a novel method for wafer level, high throughput optical chemical sensor patterning, with precise control of the sensor volume and capability of producing arbitrary microscale patterns. Monomeric oxygen (O2) and pH optical probes were polymerized with 2-hydroxyethyl methacrylate (HEMA) and acrylamide (AM) to form spin-coatable and further crosslinkable polymers. A micro-patterning method based on micro-fabrication techniques (photolithography, wet chemical process and reactive ion etch) was developed to miniaturize the sensor film onto glass substrates in arbitrary sizes and shapes. The sensitivity of fabricated micro-patterns was characterized under various oxygen concentrations and pH values. The process for spatially integration of two sensors (Oxygen and pH) on the same substrate surface was also developed, and preliminary fabrication and characterization results were presented. To the best of our knowledge, it is the first time that poly (2-hydroxylethyl methacrylate)-co-poly (acrylamide) (PHEMA-co-PAM)-based sensors had been patterned and integrated at the wafer level with micron scale precision control using microfabrication techniques. The developed methods can provide a feasible way to miniaturize and integrate the optical chemical sensor system and can be applied to any lab-on-a-chip system, especially the biological micro-systems requiring optical sensing of single or multiple analytes. PMID:23175599

  11. Patterned Magnetic Structures for Micro-/Nanoparticle and Cell Manipulation

    NASA Astrophysics Data System (ADS)

    Vieira, Gregory Butler

    Remote manipulation of fluid-borne magnetic particles on a surface is useful to probe, assemble, and sort microscale and nanoscale objects. By patterning magnetic structures in shapes designed to exploit local heterogeneities in thin film magnetization, we have demonstrated effective trapping mechanisms for superparamagnetic micro- and nanoparticles. The features necessary for trapping are shown to arise at domain walls or indentations in microscale and smaller magnetic wires, at the periphery of magnetized disks, and at corners of magnetized triangles. Weak (<150 Oe) in- and out-of-plane external magnetic fields modify the energy landscape of the trapped particles, allowing for the objects to be remotely maneuvered along selected routes across the surface. The mechanism is multiplexed, allowing for simultaneous manipulation of many trapped particles, and their motion is directed using a handheld user interface. Particles are able to be transported over hundreds of micrometers with velocities of upwards of 200 µm/s and average forces of up to hundreds of picoNewtons. The magnetic fields, their spatial distribution, and resulting forces are estimated by modeling magnetization of the patterned structures using micromagnetic simulation or by approximating the traps as point sources of fields. The quality of these models and their relevance for describing particle manipulation under the experimental conditions is discussed. The applicability of these techniques is demonstrated for various biological, biomolecular, and nanoscale systems. Binding of magnetic particles to cells allows for guided cell transport. Composite micelle nanostructures, only tens of nm across, are simultaneously trapped and maneuvered magnetically and tracked fluorescently, despite their small size. The implications for use of this technology in lab-on-chip devices are discussed.

  12. Low-Dimensional Structure Vacuum-Ultraviolet-Sensitive (λ < 200 nm) Photodetector with Fast-Response Speed Based on High-Quality AlN Micro/Nanowire.

    PubMed

    Zheng, Wei; Huang, Feng; Zheng, Ruisheng; Wu, Honglei

    2015-07-08

    A low-dimensional-structure vacuum-ultraviolet-sensitive photodetector based on high-quality aluminum nitride (AlN) micro-/nanowires is reported. This work, for the first time, demonstrates that a semiconductor nanostructure can be applied in vacuum-ultraviolet (VUV) photon detection and opens a way for developing diminutive, power-saving, and low-cost VUV materials and sensors that can be potentially applied in geospace sciences and solar-terrestrial physics.

  13. Direct fabrication of Cu/Cu2O composite micro-temperature sensor using femtosecond laser reduction patterning

    NASA Astrophysics Data System (ADS)

    Mizoshiri, Mizue; Ito, Yasuaki; Arakane, Shun; Sakurai, Junpei; Hata, Seiichi

    2016-06-01

    Micro-temperature sensors, which composed of a Cu2O-rich sensing part and two Cu-rich electrodes, were directly fabricated by femtosecond laser reduction patterning of CuO nanoparticles. Patterning of the microstructures was performed by laser scanning with pitches of 5, 10, and 15 µm. Cu2O-rich micropatterns were formed at the laser scan speed of 1 mm/s, the pitch of 5 µm, and the pulse energy of 0.54 nJ. Cu-rich micropatterns that had high generation selectivity of Cu against Cu2O were fabricated at the laser scan speed of 15 mm/s, the pitch of 5 µm, and the pulse energy of 0.45 nJ. Electrical resistivities of the Cu2O- and Cu-rich micropatterns were approximately 10 Ω m and 9 µΩ m, respectively. The temperature coefficient of the resistance of the micro-temperature sensor fabricated under these laser irradiation conditions was -5.5 × 10-3/°C. This resistance property with a negative value was consistent with that of semiconductor Cu2O.

  14. Process optimization for ultrasonic vibration assisted polishing of micro-structured surfaces on super hard material

    NASA Astrophysics Data System (ADS)

    Sun, Zhiyuan; Guo, Bing; Rao, Zhimin; Zhao, Qingliang

    2014-08-01

    In consideration of the excellent property of SiC, the ground micro-structured surface quality is hard to meet the requirement - consequently the ultrasonic vibration assisted polishing (UVAP) of micro-structures of molds is proposed in this paper. Through the orthogonal experiment, the parameters of UVAP of micro-structures were optimized. The experimental results show that, abrasive polishing process, the effect of the workpiece feed rate on the surface roughness (Ra), groove tip radius (R) and material removal rate (MRR) of micro-structures is significant. While, the UVAP, the most significant effect factor for Ra, R and MRR is the ultrasonic amplitude of the ultrasonic vibration. In addition, within the scope of the polishing process parameters selected by preliminary experiments, ultrasonic amplitude of 2.5μm, polishing force of 0.5N, workpiece feed rate of 5 mm·min-1, polishing wheel rotational speed of 50rpm, polishing time of 35min, abrasive size of 100nm and the polishing liquid concentration of 15% is the best technology of UVAP of micro-structures. Under the optimal parameters, the ground traces on the micro-structured surface were removed efficiently and the integrity of the edges of the micro-structure after grinding was maintained efficiently.

  15. Micro-fluidics and integrated optics glass sensor for in-line micro-probing of nuclear samples

    SciTech Connect

    Schimpf, A.; Canto, F.; Bucci, D.; Magnaldo, A.; Couston, L.; Broquin, J. E.

    2011-07-01

    We study the miniaturisation of Thermal Lens Spectrometry (TLS) towards Lab-on-chip integration in order to reduce the volume of fluid assays in nuclear process control. TLS is of great interest in this context since it combines the advantages of optical detection methods with an inherent suitability for small-scale samples. After validating the experimental principle in a classical thermal lens crossed-beam setup, we show the integration of a Young-interferometer with a microcapillary on a glass substrate, reducing the necessary sample size to 400 nl. The interferometer translates the photo-thermally induced refractive index change in the fluid to a phase shift of the fringe pattern, which can then be detected by a camera. Measurements of Co(II) in ethanol yield a detection limit of c = 5 x 10{sup -4} M for the crossed-beam setup and c = 6x10{sup -3} M for the integrated sensor. At an interaction length of 10 {mu}m, it detects a minimum absorbance of AU = 6 x 10{sup -5} in a probed volume of 10 pl. (authors)

  16. Micro-fluidics and integrated optics glass sensor for in-line micro-probing of nuclear samples

    SciTech Connect

    Schimpf, A.; Bucci, D.; Broquin, J.E.; Canto, F.; Magnaldo, A.; Couston, L.

    2012-08-15

    We study the miniaturization of Thermal Lens Spectrometry (TLS) towards Lab-on-chip integration in order to reduce the volume of fluid assays in nuclear process control. TLS is of great interest in this context since it combines the advantages of optical detection methods with an inherent suitability for small-scale samples. After validating the experimental principle in a classical thermal lens crossed-beam setup, we show the integration of a Young-interferometer with a microcapillary on a glass substrate, reducing the necessary sample size to 400 nl. The interferometer translates the photo-thermally induced refractive index change in the fluid to a phase shift of the fringe pattern, which can then be detected by a camera. Measurements of Co(II) in ethanol yield a detection limit of c = 5 x 10{sup -4} M for the crossed-beam setup and c = 6 x 10{sup -3} M for the integrated sensor. At an interaction length of 10 m, it detects a minimum absorbance of K = 1.2 x 10{sup -4} in a probed volume of 14 pl. (authors)

  17. Application of Point and Distributed Optical Fiber Sensors to Health Monitoring of Smart Structures

    NASA Astrophysics Data System (ADS)

    Kim, Sang Hoon; Lee, Jung Ju; Seo, Dae Cheol; Lim, Jeong Ok

    Point optical fiber sensors are useful in the monitoring of localized structural damage, but a large number of the sensors must be multiplexed for large structure monitoring. On the other hand, distributed optical fiber sensors can obtain a continuous distribution of strain or temperature with one sensing fiber, and they are suitable for the large structure monitoring due to their measurement range reaching tens of kilometers. However, the distributed sensors have the spatial resolution of tens of centimeters to several meters, and they measure averaged strain or temperature. In this paper, the application results of transmission-type extrinsic Fabry-Perot interferometric (TEFPI) optical fiber sensors and Brillouin distributed optical fiber sensors to structural monitoring are presented. The TEFPI optical fiber sensors and Brillouin distributed sensors were applied to the fatigue damage monitoring of an aluminum plate patched with CFRP composite and the deflection monitoring of an alumimum-bending beam, respectively.

  18. From Micro to Nano: The Evolution of Wireless Sensor-Based Health Care.

    PubMed

    Sarkar, Subhadeep; Misra, Sudip

    2016-01-01

    Over the past decade, embedded systems and microelectromechanical systems have evolved in a radical way, redefining our standard of living and enhancing the quality of life. Health care, among various other fields, has benefited vastly from this technological development. The concept of using sensors for health care purposes originated in the late 1980s when sensors were developed to measure certain physiological parameters associated with the human body. In traditional sensor nodes, the signal sources are mostly different environmental phenomena (such as temperature, vibration, and luminosity) or man-made events (such as intrusion and mobile target tracking), whereas in case of the physiological sensors, the signal source is living human tissue. These sensor nodes, as their primary sensing element, have a diaphragm that converts pressure into displacement. This displacement, in turn, is subsequently transformed into an electrical signal. The concept of wireless physiological sensor nodes, however, gained popularity in the mid-2000s, with the sensed data from the nodes transmitted to the hub via a wireless medium. The network formed by this heterogeneous set of wireless body sensor nodes is termed a wireless body-area network (WBAN). Each WBAN is essentially a composition of multiple wireless body sensor nodes and a single hub. The hub is primarily responsible for acquisition of the raw sensed data from all the component sensor nodes and first-level aggregation of the data before transmitting the aggregated data for further analysis to a remote data acquisition center. Here, we outline the evolution of WBANs in the context of modern health care and its convergence with nanotechnology.

  19. Micro- and Nanostructured Metal Oxide Chemical Sensors for Volatile Organic Compounds

    NASA Technical Reports Server (NTRS)

    Alim, M. A.; Penn, B. G.; Currie, J. R., Jr.; Batra, A. K.; Aggarwal, M. D.

    2008-01-01

    Aeronautic and space applications warrant the development of chemical sensors which operate in a variety of environments. This technical memorandum incorporates various kinds of chemical sensors and ways to improve their performance. The results of exploratory investigation of the binary composite polycrystalline thick-films such as SnO2-WO3, SnO2-In2O3, SnO2-ZnO for the detection of volatile organic compound (isopropanol) are reported. A short review of the present status of the new types of nanostructured sensors such as nanobelts, nanorods, nanotube, etc. based on metal oxides is presented.

  20. Development of Micro Air Vehicle Technology With In-Flight Adaptive-Wing Structure

    NASA Technical Reports Server (NTRS)

    Waszak, Martin R. (Technical Monitor); Shkarayev, Sergey; Null, William; Wagner, Matthew

    2004-01-01

    This is a final report on the research studies, "Development of Micro Air Vehicle Technology with In-Flight Adaptrive-Wing Structure". This project involved the development of variable-camber technology to achieve efficient design of micro air vehicles. Specifically, it focused on the following topics: 1) Low Reynolds number wind tunnel testing of cambered-plate wings. 2) Theoretical performance analysis of micro air vehicles. 3) Design of a variable-camber MAV actuated by micro servos. 4) Test flights of a variable-camber MAV.

  1. A two-dimensional flow sensor with integrated micro thermal sensing elements and a back propagation neural network.

    PubMed

    Que, Ruiyi; Zhu, Rong

    2013-12-31

    This paper demonstrates a novel flow sensor with two-dimensional 360° direction sensitivity achieved with a simple structure and a novel data fusion algorithm. Four sensing elements with roundabout wires distributed in four quadrants of a circle compose the sensor probe, and work in constant temperature difference (CTD) mode as both Joule heaters and temperature detectors. The magnitude and direction of a fluid flow are measured by detecting flow-induced temperature differences among the four elements. The probe is made of Ti/Au thin-film with a diameter of 2 mm, and is fabricated using micromachining techniques. When a flow goes through the sensor, the flow-induced temperature differences are detected by the sensing elements that also serve as the heaters of the sensor. By measuring the temperature differences among the four sensing elements symmetrically distributed in the sensing area, a full 360° direction sensitivity can be obtained. By using a BP neural network to model the relationship between the readouts of the four sensor elements and flow parameters and execute data fusion, the magnitude and direction of the flow can be deduced. Validity of the sensor design was proven through both simulations and experiments. Wind tunnel experimental results show that the measurement accuracy of the airflow speed reaches 0.72 m/s in the range of 3 m/s-30 m/s and the measurement accuracy of flow direction angle reaches 1.9° in the range of 360°.

  2. A Two-Dimensional Flow Sensor with Integrated Micro Thermal Sensing Elements and a Back Propagation Neural Network

    PubMed Central

    Que, Ruiyi; Zhu, Rong

    2014-01-01

    This paper demonstrates a novel flow sensor with two-dimensional 360° direction sensitivity achieved with a simple structure and a novel data fusion algorithm. Four sensing elements with roundabout wires distributed in four quadrants of a circle compose the sensor probe, and work in constant temperature difference (CTD) mode as both Joule heaters and temperature detectors. The magnitude and direction of a fluid flow are measured by detecting flow-induced temperature differences among the four elements. The probe is made of Ti/Au thin-film with a diameter of 2 mm, and is fabricated using micromachining techniques. When a flow goes through the sensor, the flow-induced temperature differences are detected by the sensing elements that also serve as the heaters of the sensor. By measuring the temperature differences among the four sensing elements symmetrically distributed in the sensing area, a full 360° direction sensitivity can be obtained. By using a BP neural network to model the relationship between the readouts of the four sensor elements and flow parameters and execute data fusion, the magnitude and direction of the flow can be deduced. Validity of the sensor design was proven through both simulations and experiments. Wind tunnel experimental results show that the measurement accuracy of the airflow speed reaches 0.72 m/s in the range of 3 m/s–30 m/s and the measurement accuracy of flow direction angle reaches 1.9° in the range of 360°. PMID:24385032

  3. Flexible and waterproof micro-sensors to uncover zebrafish circadian rhythms: The next generation of cardiac monitoring for drug screening.

    PubMed

    Zhang, Xiaoxiao; Beebe, Tyler; Jen, Nelson; Lee, Chia-An; Tai, Yuchong; Hsiai, Tzung K

    2015-09-15

    Flexible electronics are the next generation of sensors for mobile health and implantation. Zebrafish (Danio rerio) is an emergent strategy for pre-clinical drug development and toxicity testing. To address the confounding effects from sedation of fish and removal from the aquatic habitat for micro-electrocardiogram (µECG) measurements, we developed waterproof and wearable sensors to uncover the circadian variation in heart rate (HR) and heart rate variability (HRV) (Massin et al., 2000). The parylene-C based ECG sensor consisted of an ultra-soft silicone integrated jacket designed to wrap around the fish during swimming. The Young's modulus of this silicone jacket matched with the fish surface, and an extended parylene cable connected the underwater chest electrodes with the out-of water electronics. In addition, embedded micro-glass spheres in the silicone effectively reduced the effective density of the jacket to ~1 g cm(-3). These innovations enabled physiological ECG telemetry in the fish's natural habitat without the need for sedation. Furthermore, a set of non-linear signal processing techniques filtered out the breathing and electromagnetic artifacts from the recorded signals. We observed a reduction in mean HR and an increase in HRV over 24h at 10 dpa, accompanied by QT prolongation as well as diurnal variations, followed by normalization in mean HR and QT intervals at 26 days post ventricular amputation (dpa). We revealed Amiodarone-mediated QTc prolongation, HR reduction and HRV increase otherwise masked by sedation. The novel features of the flexible silicon jacket for µECG telemetry unraveled the biological clock and normalization of QT intervals at 26 dpa, providing the first evidence of new physiological phenomena during cardiac injury and repair as well as cardiac drug-mediated aberrant rhythms. Thus, the light weight and waterproof design holds promise to advance the next generation of mobile health and drug discovery.

  4. Flexible and Waterproof Micro-Sensors to Uncover Zebrafish Circadian Rhythms: The Next Generation of Cardiac Monitoring for Drug Screening

    PubMed Central

    Lee, Chia-An; Tai, Yuchong; Hsiai, Tzung K.

    2015-01-01

    Flexible electronics are the next generation of sensors for mobile health and implantation. Zebrafish (Danio rerio) is an emergent strategy for pre-clinical drug development and toxicity testing. To address the confounding effects from sedation of fish and removal from the aquatic habitat for micro-electrocardiogram (μECG) measurements, we developed waterproof and wearable sensors to uncover the circadian variation in heart rate (HR) and heart rate variability (HRV)[1]. The parylene-C based ECG sensor consisted of an ultra-soft silicone integrated jacket designed to wrap around the fish during swimming. The Young’s modulus of this silicone jacket matched with the fish surface, and an extended parylene cable connected the underwater chest electrodes with the out-of water electronics. In addition, embedded micro-glass spheres in the silicone effectively reduced the effective density of the jacket to ~ 1 g·cm−3. These innovations enabled physiological ECG telemetry in the fish’s natural habitat without the need for sedation. Furthermore, a set of non-linear signal processing techniques filtered out the breathing and electromagnetic artifacts from the recorded signals. We observed a reduction in mean HR and an increase in HRV over 24 hours at 10 dpa, accompanied by QT prolongation as well as diurnal variations, followed by normalization in mean HR and QT intervals at 26 days post ventricular amputation (dpa). We revealed Amiodarone-mediated QTc prolongation, HR reduction and HRV increase otherwise masked by sedation. The novel features of the flexible silicon jacket for μECG telemetry unraveled the biological clock and normalization of QT intervals at 26 dpa, providing the first evidence of new physiological phenomena during cardiac injury and repair as well as cardiac drug-mediated aberrant rhythms. Thus, the light weight and waterproof design holds promise to advance the next generation of mobile health and drug discovery. PMID:25909335

  5. Nano-based sensor for assessment of weaponry structural degradation

    NASA Astrophysics Data System (ADS)

    Brantley, Christina L.; Edwards, Eugene; Ruffin, Paul B.; Kranz, Michael

    2016-04-01

    Missiles and weaponry-based systems are composed of metal structures that can degrade after prolonged exposure to environmental elements. A particular concern is accumulation of corrosion that generally results from prolonged environmental exposure. Corrosion, defined as the unintended destruction or deterioration of a material due to its interaction with the environment, can negatively affect both equipment and infrastructure. System readiness and safety can be reduced if corrosion is not detected, prevented and managed. The current corrosion recognition methods (Visual, Radiography, Ultrasonics, Eddy Current, and Thermography) are expensive and potentially unreliable. Visual perception is the most commonly used method for determining corrosion in metal. Utilization of an inductance-based sensor system is being proposed as part of the authors' research. Results from this research will provide a more efficient, economical, and non-destructive sensing approach. Preliminary results demonstrate a highly linear degradation within a corrosive environment due to the increased surface area available on the sensor coupon. The inductance of the devices, which represents a volume property of the coupon, demonstrated sensitivity to corrosion levels. The proposed approach allows a direct mass-loss measurement based on the change in the inductance of the coupon when placed in an alternating magnetic field. Prototype devices have demonstrated highly predictable corrosion rates that are easily measured using low-power small electronic circuits and energy harvesting methods to interrogate the sensor. Preliminary testing demonstrates that the device concept is acceptable and future opportunities for use in low power embedded applications are achievable. Key results in this paper include the assessment of typical Army corrosion cost, degradation patterns of varying metal materials, and application of wireless sensors elements.

  6. A neighbor pixel communication filtering structure for Dynamic Vision Sensors

    NASA Astrophysics Data System (ADS)

    Xu, Yuan; Liu, Shiqi; Lu, Hehui; Zhang, Zilong

    2017-02-01

    For Dynamic Vision Sensors (DVS), thermal noise and junction leakage current induced Background Activity (BA) is the major cause of the deterioration of images quality. Inspired by the smoothing filtering principle of horizontal cells in vertebrate retina, A DVS pixel with Neighbor Pixel Communication (NPC) filtering structure is proposed to solve this issue. The NPC structure is designed to judge the validity of pixel's activity through the communication between its 4 adjacent pixels. The pixel's outputs will be suppressed if its activities are determined not real. The proposed pixel's area is 23.76×24.71μm2 and only 3ns output latency is introduced. In order to validate the effectiveness of the structure, a 5×5 pixel array has been implemented in SMIC 0.13μm CIS process. 3 test cases of array's behavioral model show that the NPC-DVS have an ability of filtering the BA.

  7. Performance of a novel micro force vector sensor and outlook into its biomedical applications

    NASA Astrophysics Data System (ADS)

    Meiss, Thorsten; Rossner, Tim; Minamisava Faria, Carlos; Völlmeke, Stefan; Opitz, Thomas; Werthschützky, Roland

    2011-05-01

    For the HapCath system, which provides haptic feedback of the forces acting on a guide wire's tip during vascular catheterization, very small piezoresistive force sensors of 200•200•640μm3 have been developed. This paper focuses on the characterization of the measurement performance and on possible new applications. Besides the determination of the dynamic measurement performance, special focus is put onto the results of the 3- component force vector calibration. This article addresses special advantageous characteristics of the sensor, but also the limits of applicability will be addressed. As for the special characteristics of the sensor, the second part of the article demonstrates new applications which can be opened up with the novel force sensor, like automatic navigation of medical or biological instruments without impacting surrounding tissue, surface roughness evaluation in biomedical systems, needle insertion with tactile or higher level feedback, or even building tactile hairs for artificial organisms.

  8. Truss structure integrity identification using PZT sensor-actuator

    SciTech Connect

    Sun, F.P.; Chaudhry, Z.; Liang, C.; Rogers, C.A.

    1994-12-31

    This paper presents a frequency domain impedance-signature-based technique for health monitoring of an assembled truss structure. Unlike conventional modal analysis approaches, the technique uses piezoceramic (PZT) elements as integrated sensor-actuators for acquisition of signature pattern of the truss. The concept of the localization of sensing/actuation area for damage detection of an assembled structure is presented for the first time. Through a PZT patch bonded to a truss node and the measurement of its electric admittance, which is coupled with the mechanical impedance of the truss, the signature pattern of a truss is monitored. The admittance of a truss in question is compared with that of the original healthy truss. Statistic algorithm is then applied to extract a damage index of the truss based on the signature pattern difference. Experimental proof that over a selected band, the detection range of a bonded PZT sensor on a truss is highly constrained to its immediate neighborhood is presented. This characteristic allows accurate determination of the damage location in a complex real-world structure with a minimum mathematical modeling and numerical computation.

  9. Aluminum alloy material structure impact localization by using FBG sensors

    NASA Astrophysics Data System (ADS)

    Zhu, Xiubin

    2014-12-01

    The aluminum alloy structure impact localization system by using fiber Bragg grating (FBG) sensors and impact localization algorithm was investigated. A four-FBG sensing network was established. And the power intensity demodulation method was initialized employing the narrow-band tunable laser. The wavelet transform was used to weaken the impact signal noise. And the impact signal time difference was extracted to build the time difference localization algorithm. At last, a fiber Bragg grating impact localization system was established and experimentally verified. The experimental results showed that in the aluminum alloy plate with the 500 mm*500 mm*2 mm test area, the maximum and average impact abscissa localization errors were 11 mm and 6.25 mm, and the maximum and average impact ordinate localization errors were 9 mm and 4.25 mm, respectively. The fiber Bragg grating sensors and demodulation system are feasible to realize the aviation aluminum alloy material structure impact localization. The research results provide a reliable method for the aluminum alloy material structure impact localization.

  10. Partial recovery of the magnetoelectrical properties of AlGaN/GaN-based micro-Hall sensors irradiated with protons

    SciTech Connect

    Abderrahmane, A.; Tashiro, T.; Takahashi, H.; Ko, P. J.; Okada, H.; Sandhu, A.; Sato, S.; Ohshima, T.

    2014-01-13

    The effect of annealing on the magnetoelectrical properties of proton-irradiated micro-Hall sensors at an energy of 380 keV and very high proton fluences was studied. Recovery of the electron mobility and a decrease in the sheet resistance of the annealed micro-Hall sensors, as well as an enhancement in their magnetic sensitivity were reported. Trap removal and an improvement in the crystal quality by removing defects were confirmed through current–voltage measurements and Raman spectroscopy, respectively.

  11. Parallel robot for micro assembly with integrated innovative optical 3D-sensor

    NASA Astrophysics Data System (ADS)

    Hesselbach, Juergen; Ispas, Diana; Pokar, Gero; Soetebier, Sven; Tutsch, Rainer

    2002-10-01

    Recent advances in the fields of MEMS and MOEMS often require precise assembly of very small parts with an accuracy of a few microns. In order to meet this demand, a new approach using a robot based on parallel mechanisms in combination with a novel 3D-vision system has been chosen. The planar parallel robot structure with 2 DOF provides a high resolution in the XY-plane. It carries two additional serial axes for linear and rotational movement in/about z direction. In order to achieve high precision as well as good dynamic capabilities, the drive concept for the parallel (main) axes incorporates air bearings in combination with a linear electric servo motors. High accuracy position feedback is provided by optical encoders with a resolution of 0.1 μm. To allow for visualization and visual control of assembly processes, a camera module fits into the hollow tool head. It consists of a miniature CCD camera and a light source. In addition a modular gripper support is integrated into the tool head. To increase the accuracy a control loop based on an optoelectronic sensor will be implemented. As a result of an in-depth analysis of different approaches a photogrammetric system using one single camera and special beam-splitting optics was chosen. A pattern of elliptical marks is applied to the surfaces of workpiece and gripper. Using a model-based recognition algorithm the image processing software identifies the gripper and the workpiece and determines their relative position. A deviation vector is calculated and fed into the robot control to guide the gripper.

  12. Test Structures for Rapid Prototyping of Gas and Pressure Sensors

    NASA Technical Reports Server (NTRS)

    Buehler, M.; Cheng, L. J.; Martin, D.

    1996-01-01

    A multi-project ceramic substrate was used in developing a gas sensor and pressure sensor. The ceramic substrate cantained 36 chips with six variants including sensors, process control monitors, and an interconnect ship. Tha gas sensor is being developed as an air quality monitor and the pressure gauge as a barometer.

  13. Applications of a nanocomposite-inspired in-situ broadband ultrasonic sensor to acousto-ultrasonics-based passive and active structural health monitoring.

    PubMed

    Liu, Menglong; Zeng, Zhihui; Xu, Hao; Liao, Yaozhong; Zhou, Limin; Zhang, Zhong; Su, Zhongqing

    2017-03-14

    A novel nanocomposite-inspired in-situ broadband ultrasonic sensor previously developed, with carbon black as the nanofiller and polyvinylidene fluoride as the matrix, was networked for acousto-ultrasonic wave-based passive and active structural health monitoring (SHM). Being lightweight and small, this kind of sensor was proven to be capable of perceiving strain perturbation in virtue of the tunneling effect in the formed nanofiller conductive network when acousto-ultrasonic waves traverse the sensor. Proof-of-concept validation was implemented, to examine the sensor performance in responding to acousto-ultrasonic waves in a broad frequency regime: from acoustic emission (AE) of lower frequencies to guided ultrasonic waves (GUWs) of higher frequencies. Results have demonstrated the high fidelity, ultrafast response and high sensitivity of the sensor to acousto-ultrasonic waves up to 400kHz yet with an ultra-low magnitude (of the order of micro-strain). The sensor is proven to possess sensitivity and accuracy comparable with commercial piezoelectric ultrasonic transducers, whereas with greater flexibility in accommodating curved structural surfaces. Application paradigms of using the sensor for damage evaluation have spotlighted the capability of the sensor in compromising "sensing cost" with "sensing effectiveness" for passive AE- or active GUW-based SHM.

  14. Loss of superhydrophobicity of hydrophobic micro/nano structures during condensation.

    PubMed

    Jo, HangJin; Hwang, Kyung Won; Kim, DongHyun; Kiyofumi, Moriyama; Park, Hyun Sun; Kim, Moo Hwan; Ahn, Ho Seon

    2015-04-23

    Condensed liquid behavior on hydrophobic micro/nano-structured surfaces is a subject with multiple practical applications, but remains poorly understood. In particular, the loss of superhydrophobicity of hydrophobic micro/nanostructures during condensation, even when the same surface shows water-repellant characteristics when exposed to air, requires intensive investigation to improve and apply our understanding of the fundamental physics of condensation. Here, we postulate the criterion required for condensation to form from inside the surface structures by examining the grand potentials of a condensation system, including the properties of the condensed liquid and the conditions required for condensation. The results imply that the same hydrophobic micro/nano-structured surface could exhibit different liquid droplet behavior depending on the conditions. Our findings are supported by the observed phenomena: the initiation of a condensed droplet from inside a hydrophobic cavity, the apparent wetted state changes, and the presence of sticky condensed droplets on the hydrophobic micro/nano-structured surface.

  15. Micro pH Sensors and Biosensors Based on Electrochemical Field Effect Transistors

    NASA Astrophysics Data System (ADS)

    Sasano, Junji; Niwa, Daisuke; Osaka, Tetsuya

    A study on ion-sensing using field effect transistor (FET) was begun by Bergveld in the 1970s [1-3]. The ion-sensitive (IS) FET is now widely used as a miniaturized pH sensor, commercialized by some companies. First, the principle and structure of the ISFET are introduced in this section. A basic design of ISFET is shown in Fig. 10.1 a. ISFET has silicon substrate with field-effect structures such as electrolyte/IS layer/(insulator)/semiconductor structures; the space charge region in the semiconductor is modulated depending on the gate voltage (V g), same as a typical metal-oxide-semiconductor (MOS) FET. A typical bias V g versus drain-source current (I ds) characteristic of the device that has silicon nitride/silicon dioxide/silicon is shown in Fig. 10.1 b. This characteristic is quite similar to the MOSFET. A prominent difference between ISFET and MOSFET is that the gate voltage for the operation of the device is applied by an electrochemical reference electrode through the electrolyte in contact with the gate insulator. The threshold voltage (V th) could shift according to the value of the pH of the solution. In the MOSFET, the V th would shift depending on the change in the space charge region in the MOS capacitor structure by the application of V g. On the other hand, the V th in ISFET would shift according to the change in the surface potential in the electrolyte/IS layer interface. Therefore, the IS layers and their interfaces in ISFET play an important role in the performance of pH responsibility. It is well-known that the silicon nitride surface shows a good pH response in solution. The silicon nitride layer is often formed by plasma-enhanced chemical vapor deposition (PECVD), which is generally formed at the thickness of 100-500 nm. The V g vs. I ds, characteristics of the silicon nitride-based ISFET indicate a good pH responsibility of 58 mV/decade that shows Nernstian response (Fig. 10.1 c). The shift of the V th depends on the changes of surface

  16. A Phase-tracking Snow Micro-structure Model

    NASA Astrophysics Data System (ADS)

    Slaughter, A. E.; Zabaras, N.

    2012-12-01

    Utilizing a methodology derived from models for phase transitions in alloy solidification [1], a 3D finite element (FE) model for snow metamorphism was developed. Avalanches are known to occur due to the existence of a weak-layer of faceted crystals, which form due to temperature gradients within the snow through a process known as kinetic metamorphism [2]. In general, snow models are limited in their ability to model these microstructural changes, especially in three dimensions, and rely on effective properties. To enhance the tools available to avalanche researchers a finite element model was developed capable of tracking vapor deposition within the snow. This is accomplished using a fixed-domain, stabilized finite element solution for the energy, mass, momentum, and transport equations. Using a level-set parameter the domain is separated into either solid or fluid components and along the phase-change boundary a "mushy-zone" is establish [1, 3]. This zone is modeled as porous media that includes the effects of shrinkage and density changes [1]. The basis of the model is the open-source C++ libMesh FE library, as such the model includes adaptive mesh coarsening and refinement and relies on domain decomposition for optimum parallel performance. This work is the initial phase of an ongoing research project that aims to demonstrate the ability to model snow at the micro-structural level and move away from the common coarse, effective property modeling techniques. It will serve as the deterministic basis for a multi-scale, stochastic model of snow that will account for uncertainties such as poorly understood growth properties and measurement variability. Future applications may include the inclusion of liquid melt and include external forces, yielding a comprehensive thermo-mechanical model that could evolve and fracture. [1] D. Samanta, N. Zabaras (2005), Modelling convection in solidification processes using stabilized finite element techniques, J. Numer. Meth. Eng

  17. Fibre Optic Sensors for Structural Health Monitoring of Aircraft Composite Structures: Recent Advances and Applications

    PubMed Central

    Di Sante, Raffaella

    2015-01-01

    In-service structural health monitoring of composite aircraft structures plays a key role in the assessment of their performance and integrity. In recent years, Fibre Optic Sensors (FOS) have proved to be a potentially excellent technique for real-time in-situ monitoring of these structures due to their numerous advantages, such as immunity to electromagnetic interference, small size, light weight, durability, and high bandwidth, which allows a great number of sensors to operate in the same system, and the possibility to be integrated within the material. However, more effort is still needed to bring the technology to a fully mature readiness level. In this paper, recent research and applications in structural health monitoring of composite aircraft structures using FOS have been critically reviewed, considering both the multi-point and distributed sensing techniques. PMID:26263987

  18. Fibre Optic Sensors for Structural Health Monitoring of Aircraft Composite Structures: Recent Advances and Applications.

    PubMed

    Di Sante, Raffaella

    2015-07-30

    In-service structural health monitoring of composite aircraft structures plays a key role in the assessment of their performance and integrity. In recent years, Fibre Optic Sensors (FOS) have proved to be a potentially excellent technique for real-time in-situ monitoring of these structures due to their numerous advantages, such as immunity to electromagnetic interference, small size, light weight, durability, and high bandwidth, which allows a great number of sensors to operate in the same system, and the possibility to be integrated within the material. However, more effort is still needed to bring the technology to a fully mature readiness level. In this paper, recent research and applications in structural health monitoring of composite aircraft structures using FOS have been critically reviewed, considering both the multi-point and distributed sensing techniques.

  19. Heat treatment giving a stable high temperature micro-structure in cast austenitic stainless steel

    DOEpatents

    Anton, Donald L.; Lemkey, Franklin D.

    1988-01-01

    A novel micro-structure developed in a cast austenitic stainless steel alloy and a heat treatment thereof are disclosed. The alloy is based on a multicomponent Fe-Cr-Mn-Mo-Si-Nb-C system consisting of an austenitic iron solid solution (.gamma.) matrix reinforced by finely dispersed carbide phases and a heat treatment to produce the micro-structure. The heat treatment includes a prebraze heat treatment followed by a three stage braze cycle heat treatment.

  20. Micro-Structured Materials for Generation of Coherent Light and Optical Signal Processing

    DTIC Science & Technology

    2008-12-22

    within a laser linewidth of 1 GHz (matched to the doppler broadened bandwidth of the sodium layer) to provide enough return light to the wavefront...AND SUBTITLE Micro-Structured Materials for Generation of Coherent Light And Optical Signal Processing 5a. CONTRACT NUMBER 5b. GRANT NUMBER...2008 3. TITLE OF PROPOSAL: Micro-Structured Matenals for Generation of Coherent Light And Optical Signal Processing 4. LIST OF MANUSCRIPTS

  1. Development of Active Catheter,Active Guide Wire and Micro Sensor Systems

    PubMed Central

    Haga, Y.; Mineta, T.; Totsu, K.; Makishi, W.; Esashi, M.

    2001-01-01

    Summary Active catheters and active guide wires which move like a snake have been developed for catheter-based minimally invasive diagnosis and therapy. Communication and control IC chips in the active catheter reduce the number of lead wires for control. The active catheter can be not only bent but also torsioned and extended. An ultra minature fiber-optic pressure sensor; a forward-looking ultrasonic probe and a magnetic position and orientation sensor have been developed for catheters and guide wires. These moving mechanisms and several sensors which are fitted near the tip of the catheter and the guide wire will provide detailed information near the tip and enable delicate and effective catheter intervention. PMID:20663389

  2. Characterization of silicon micro-strip sensors with a pulsed infra-red laser system for the CBM experiment at FAIR

    NASA Astrophysics Data System (ADS)

    Ghosh, P.

    2015-03-01

    The Compressed Baryonic Matter (CBM) experiment at FAIR is composed of 8 tracking stations consisting of 1292 double sided silicon micro-strip sensors. For the quality assurance of produced prototype sensors a laser test system (LTS) has been developed. The aim of the LTS is to scan sensors with a pulsed infra-red laser driven by step motor to determine the charge sharing in-between strips and to measure qualitative uniformity of the sensor response over the whole active area. The prototype sensors which are tested with the LTS so far have 256 strips with a pitch of 50 μm on each side. They are read-out using a self-triggering prototype read-out electronic ASIC called n-XYTER. The LTS is designed to measure sensor response in an automatized procedure at several thousand positions across the sensor with focused infra-red laser light (spot size ≈ 12 μm , wavelength = 1060 nm). The pulse with duration (≈ 10 ns) and power (≈ 5 mW) of the laser pulses is selected such, that the absorption of the laser light in the 300 μm thick silicon sensors produces a number of about 24000 electrons, which is similar to the charge created by minimum ionizing particles (MIP) in these sensors. Laser scans different prototype sensors is reported.

  3. Diamond machining of micro-optical components and structures

    NASA Astrophysics Data System (ADS)

    Gläbe, Ralf; Riemer, Oltmann

    2010-05-01

    Diamond machining originates from the 1950s to 1970s in the USA. This technology was originally designed for machining of metal optics at macroscopic dimensions with so far unreached tolerances. During the following decades the machine tools, the monocrystalline diamond cutting tools, the workpiece materials and the machining processes advanced to even higher precision and flexibility. For this reason also the fabrication of small functional components like micro optics at a large spectrum of geometries became technologically and economically feasible. Today, several kinds of fast tool machining and multi axis machining operations can be applied for diamond machining of micro optical components as well as diffractive optical elements. These parts can either be machined directly as single or individual component or as mold insert for mass production by plastic replication. Examples are multi lens arrays, micro mirror arrays and fiber coupling lenses. This paper will give an overview about the potentials and limits of the current diamond machining technology with respect to micro optical components.

  4. Structural Health Monitoring of Composite Structures Using Fiber Optic Sensors

    NASA Astrophysics Data System (ADS)

    Williams, Charles Phillip Michael

    In an aircraft engine at high altitude, the low-pressure turbine (LPT) section can experience low-Reynolds number (Re) flows making the turbine blades susceptible to large separation losses. These losses are detrimental to the performance of the turbine and lead to a roadblock for "higher-lift" blade designs. Accurate prediction of the separation characteristics and an understanding of mitigation techniques are of the utmost importance. The current study conducts simulations of flow control techniques for the Air Force Research Laboratory (AFRL) L2A turbine blade at low-Re of 10,000 based on inlet velocity and blade axial chord. This blade was selected for its "high-lift" characteristics coupled with massive separation on the blade at low-Re which provides an excellent test blade for flow control techniques. Flow control techniques involved various configurations of vortex generator jets (VGJs) using momentum injection (i.e. jet blowing). All computations were executed on dual-topology, multi-block, structured meshes and incorporated the use of a parallel computing platform using the message passing interface (MPI) communications. A high-order implicit large eddy simulation (ILES) approach was used in the simulations allowing for a seamless transition between laminar, transitional, and turbulent flow without changing flow solver parameters. A validation study was conducted involving an AFRL L1A turbine blade which showed good agreement with experimental trends for cases which controlled separation in the experiments. The same cases showed good agreement between different grid sizes. The differences between experimental and numerical results are largely attributed to differences in the setup. That is, the simulation did not include freestream turbulence or wind-tunnel wall effects. The flow control study conducted for the L2A blade showed a small degree of separation control for jets placed just downstream (DS) of the separation point. A limited study was conducted

  5. Ultrasonic Sensor Placement Optimization in Structural Health Monitoring Using Evolutionary Strategy

    NASA Astrophysics Data System (ADS)

    Gao, H.; Rose, J. L.

    2006-03-01

    In structural health monitoring (SHM), sensor network scale and sensor distribution decisions are critical since sensor network performance and system cost are greatly affected. A quantitative sensor placement optimization method with covariance matrix adaptation evolutionary strategy (CMAES) is presented in this paper. A damage detection probability model is developed for ultrasonic guided wave sensor networks. Two sample problems are presented in this paper. One is for structure with irregular damage distribution probability, and the other is for an E2 aircraft wing section. The reliability of this genetic and evolutionary optimization method is proved in this study. Sensor network configurations with minimum missed-detection probability are obtained from the results of evolutionary optimization. The tradeoff relationship between optimized sensor network performance and the number of sensors is also presented in this paper.

  6. Development and preliminary results of bimanual smart micro-surgical system using a ball-lens coupled OCT distance sensor.

    PubMed

    Koo, Dongwoo; Park, Hyun-Cheol; Gehlbach, Peter L; Song, Cheol

    2016-11-01

    Bimanual surgery enhances surgical effectiveness and is required to successfully accomplish complex microsurgical tasks. The essential advantage is the ability to simultaneously grasp tissue with one hand to provide counter traction or exposure, while dissecting with the other. Towards enhancing the precision and safety of bimanual microsurgery we present a bimanual SMART micro-surgical system for a preliminary ex-vivo study. To the best of our knowledge, this is the first demonstration of a handheld bimanual microsurgical system. The essential components include a ball-lens coupled common-path swept source optical coherence tomography sensor. This system effectively suppresses asynchronous hand tremor using two PZT motors in feedback control loop and efficiently assists ambidextrous tasks. It allows precise bimanual dissection of biological tissues with a reduction in operating time as compared to the same tasks performed with conventional one-handed approaches.

  7. A portable instrument for continuous glucose monitoring by the integration of microfluidic chip and micro-glucose sensor

    NASA Astrophysics Data System (ADS)

    Li, Dachao; Ji, Yongjie; Liang, Wenshuai; Zhang, Xiaoli; Yu, Haixia; Xu, Kexin

    2013-03-01

    Interstitial fluid (ISF) can be transdermally extracted using low-frequency ultrasound and continuous vacuum pressure on skin surface. But the tiny volume of transdermally extracted ISF makes the transdermal extraction, collection, transport, volumetric detection and glucose concentration measurement of the ISF very difficult. Based on a microfluidic chip for transdermally extraction of interstitial fluid and a micro glucose sensor for glucose concentration measurement, a continuous glucose monitoring instrumentby ISF transdermal extraction with minimally invasive way is developed. In the paper, various parts of the device and their interface circuits are designed; the hardware and software of the instrument are built; the simulating experiments of transdermal ISF extraction, collection and volume measurement with full-thickness pig skin are performed using this integrated system; and the functionalities of this device is verified for future clinical application.

  8. Development and preliminary results of bimanual smart micro-surgical system using a ball-lens coupled OCT distance sensor

    PubMed Central

    Koo, Dongwoo; Park, Hyun-Cheol; Gehlbach, Peter L.; Song, Cheol

    2016-01-01

    Bimanual surgery enhances surgical effectiveness and is required to successfully accomplish complex microsurgical tasks. The essential advantage is the ability to simultaneously grasp tissue with one hand to provide counter traction or exposure, while dissecting with the other. Towards enhancing the precision and safety of bimanual microsurgery we present a bimanual SMART micro-surgical system for a preliminary ex-vivo study. To the best of our knowledge, this is the first demonstration of a handheld bimanual microsurgical system. The essential components include a ball-lens coupled common-path swept source optical coherence tomography sensor. This system effectively suppresses asynchronous hand tremor using two PZT motors in feedback control loop and efficiently assists ambidextrous tasks. It allows precise bimanual dissection of biological tissues with a reduction in operating time as compared to the same tasks performed with conventional one-handed approaches. PMID:27896018

  9. Toward a Micro-Scale Acoustic Direction-Finding Sensor with Integrated Electronic Readout

    DTIC Science & Technology

    2013-06-01

    1998. [4] A. C. Mason , M. L. Oshinsky, and R. R. Hoy, “Hyperacute directional hearing in a mi- croscale auditory system,” Nature, vol. 410, pp. 686...mechanical (MEMS) sound sensor,” Master’s thesis, Naval Postgraduate School, 2012. [35] J. D. Roth , “Integration of a high sensitivity MEMS directional

  10. Designing an Electronic Readout for a Directional Micro Electro-Mechanical (MEMS) Sound Sensor

    DTIC Science & Technology

    2011-12-01

    Pins CHPRST, V2P25, TESTSEL, SDATA & SCLK are required for data comunications from the computer to the MS3110 IC/die and pins VDD & GND are...LIST OF REFERENCES [1] Irvine Sensors Corporation , “MS3110 universal capacitive readoutTM IC data sheet,” May 2004. [2] K. Simsek, “Developing a

  11. Micro-optical components and systems in polymers for optical networks and sensors

    NASA Astrophysics Data System (ADS)

    Teubner, Ulrich

    2004-09-01

    Miniaturization of precision optical components offers the opportunity for highly integrated high performance but lowcost devices for a wide field of applications. An increasing amount of examples could be found in the optical communication market and in sensor technology. Basing on several examples, we discuss actual developments in both fields.

  12. Visualization and Analysis of Wireless Sensor Network Data for Smart Civil Structure Applications Based On Spatial Correlation Technique

    NASA Astrophysics Data System (ADS)

    Chowdhry, Bhawani Shankar; White, Neil M.; Jeswani, Jai Kumar; Dayo, Khalil; Rathi, Manorma

    2009-07-01

    Disasters affecting infrastructure, such as the 2001 earthquakes in India, 2005 in Pakistan, 2008 in China and the 2004 tsunami in Asia, provide a common need for intelligent buildings and smart civil structures. Now, imagine massive reductions in time to get the infrastructure working again, realtime information on damage to buildings, massive reductions in cost and time to certify that structures are undamaged and can still be operated, reductions in the number of structures to be rebuilt (if they are known not to be damaged). Achieving these ideas would lead to huge, quantifiable, long-term savings to government and industry. Wireless sensor networks (WSNs) can be deployed in buildings to make any civil structure both smart and intelligent. WSNs have recently gained much attention in both public and research communities because they are expected to bring a new paradigm to the interaction between humans, environment, and machines. This paper presents the deployment of WSN nodes in the Top Quality Centralized Instrumentation Centre (TQCIC). We created an ad hoc networking application to collect real-time data sensed from the nodes that were randomly distributed throughout the building. If the sensors are relocated, then the application automatically reconfigures itself in the light of the new routing topology. WSNs are event-based systems that rely on the collective effort of several micro-sensor nodes, which are continuously observing a physical phenomenon. WSN applications require spatially dense sensor deployment in order to achieve satisfactory coverage. The degree of spatial correlation increases with the decreasing inter-node separation. Energy consumption is reduced dramatically by having only those sensor nodes with unique readings transmit their data. We report on an algorithm based on a spatial correlation technique that assures high QoS (in terms of SNR) of the network as well as proper utilization of energy, by suppressing redundant data transmission

  13. Curved hierarchically micro-micro structured polypropylene surfaces by injection molding

    NASA Astrophysics Data System (ADS)

    Mielonen, K.; Suvanto, M.; Pakkanen, T. A.

    2017-01-01

    Structural hierarchy of polymer surfaces has been of central interest due to its diverse surface functionalities. However, the research on hierarchically structured polymer surfaces has been focused on planar surfaces even though applications may also be variously curved. This study demonstrates the fabrication of curved rigid polymer surfaces with precisely controlled hierarchical microstructures. The surface structuration was made on an aluminum foil with a microworking robot, and polypropylene replicas were produced by injection molding. Depending on the mold structuration procedure, the curved mold can have either radially or vertically oriented structures. Both convex and concave curvatures were here applied to spherically and cylindrically curved surfaces. A simple structure protection technique was applied to support the structures during mechanical bending of the foil. The planar hierarchically microstructured polypropylene surfaces were characterized to exhibit superhydrophobicity, and similar structures were obtained on the curved surfaces. Introducing the curvature to the hierarchically structured surfaces may further widen the applicability of functionalized polymer surfaces.

  14. Piezo impedance sensors to monitor degradation of biological structure

    NASA Astrophysics Data System (ADS)

    Annamdas, Kiran Kishore Kumar; Annamdas, Venu Gopal Madhav

    2010-04-01

    In some countries it is common to have wooden structures in their homes, especially Japan. However, metals and its alloys are the most widely used engineering materials in construction of any military or civil structure. Re-visiting natural disasters like the recent Haiti earthquake (12 Jan 2010) or Katrina (cyclones) reminds the necessity to have better housing infrastructure with robust monitoring systems. Traditionally wood (green material) was accepted as excellent rehabilitation material, after any disaster. In recent times, the recycling materials extracted from inorganic, biodegradable wastes are converted into blocks or sheets, and are also used to assist public in rehabilitation camps. The key issue which decreases the life of these rehabilitated structure including green materials (like wood) is unnecessary degradation or deterioration over time due to insect or acid attack or rain/ice fall. The recycling material also needs monitoring to protect them against acid or rain/ice attacks. Thus, a few health monitoring techniques have emerged in the recent past. Electromechanical Impedance technique is one such technique, which is simple but robust to detect variations in the integrity of structures. In this paper, impedance based piezoceramic sensor was bonded on wooden sample, which was subjected to degradation in presence of acids. Variations in mass of plank are studied.

  15. Impedance based sensor technology to monitor stiffness of biological structures

    NASA Astrophysics Data System (ADS)

    Annamdas, Venu Gopal Madhav; Annamdas, Kiran Kishore Kumar

    2010-04-01

    In countries like USA or Japan it is not so uncommon to have wooden structures in their homes. However, metals and its alloys are the most widely used engineering materials in construction of any military or civil structure. Revisiting natural disasters like the recent Haiti earthquake (12 Jan 2010) or Katrina (cyclones) reminds the necessity to have better housing infrastructure with robust monitoring systems. Traditionally wood is accepted as excellent rehabilitation material, after any disaster. The recycling materials extracted from in-organic, biodegradable wastes, also can be used for rehabilitation. The key issue which dampens the life of these rehabilitated structure including green materials (like wood) is unnecessary deposits (nails, screws, bolts etc)/damages due to insect attack. Thus, a few health monitoring techniques have emerged in the recent past. Electromechanical Impedance technique is one such technique, which is simple but robust to detect variations in the integrity of structures. In this paper, impedance based piezoceramic sensor was bonded on wooden sample, which was used to study changes due to metallic (steel nails) deposits at various locations. A study of weight deposits on aluminum plate was used for comparisons.

  16. Micro Hopping Robots for Rescue Operation: Many Tiny Robots with a Single Sensor and Launcher System

    DTIC Science & Technology

    2007-03-25

    victims within collapsed buildings . The approach is to use many small robots that search downward (using gravity, rather than a power source) as the best...unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 1. Introduction <Background> Collapsed buildings due to earthquake or...developed to detect survivors under collapsed buildings . This small robot includes micro eccentric motors for generating lift and thrust forces, and IR

  17. Rapid electronic detection of probe-specific microRNAs using thin nanopore sensors

    NASA Astrophysics Data System (ADS)

    Wanunu, Meni; Dadosh, Tali; Ray, Vishva; Jin, Jingmin; McReynolds, Larry; Drndić, Marija

    2010-11-01

    Small RNA molecules have an important role in gene regulation and RNA silencing therapy, but it is challenging to detect these molecules without the use of time-consuming radioactive labelling assays or error-prone amplification methods. Here, we present a platform for the rapid electronic detection of probe-hybridized microRNAs from cellular RNA. In this platform, a target microRNA is first hybridized to a probe. This probe:microRNA duplex is then enriched through binding to the viral protein p19. Finally, the abundance of the duplex is quantified using a nanopore. Reducing the thickness of the membrane containing the nanopore to 6 nm leads to increased signal amplitudes from biomolecules, and reducing the diameter of the nanopore to 3 nm allows the detection and discrimination of small nucleic acids based on differences in their physical dimensions. We demonstrate the potential of this approach by detecting picogram levels of a liver-specific miRNA from rat liver RNA.

  18. Monolithic carbon structures including suspended single nanowires and nanomeshes as a sensor platform

    PubMed Central

    2013-01-01

    With the development of nanomaterial-based nanodevices, it became inevitable to develop cost-effective and simple nanofabrication technologies enabling the formation of nanomaterial assembly in a controllable manner. Herein, we present suspended monolithic carbon single nanowires and nanomeshes bridging two bulk carbon posts, fabricated in a designed manner using two successive UV exposure steps and a single pyrolysis step. The pyrolysis step is accompanied with a significant volume reduction, resulting in the shrinkage of micro-sized photoresist structures into nanoscale carbon structures. Even with the significant elongation of the suspended carbon nanowire induced by the volume reduction of the bulk carbon posts, the resultant tensional stress along the nanowire is not significant but grows along the wire thickness; this tensional stress gradient and the bent supports of the bridge-like carbon nanowire enhance structural robustness and alleviate the stiction problem that suspended nanostructures frequently experience. The feasibility of the suspended carbon nanostructures as a sensor platform was demonstrated by testing its electrochemical behavior, conductivity-temperature relationship, and hydrogen gas sensing capability. PMID:24256942

  19. Design and Analysis of a Single-Camera Omnistereo Sensor for Quadrotor Micro Aerial Vehicles (MAVs) †

    PubMed Central

    Jaramillo, Carlos; Valenti, Roberto G.; Guo, Ling; Xiao, Jizhong

    2016-01-01

    We describe the design and 3D sensing performance of an omnidirectional stereo (omnistereo) vision system applied to Micro Aerial Vehicles (MAVs). The proposed omnistereo sensor employs a monocular camera that is co-axially aligned with a pair of hyperboloidal mirrors (a vertically-folded catadioptric configuration). We show that this arrangement provides a compact solution for omnidirectional 3D perception while mounted on top of propeller-based MAVs (not capable of large payloads). The theoretical single viewpoint (SVP) constraint helps us derive analytical solutions for the sensor’s projective geometry and generate SVP-compliant panoramic images to compute 3D information from stereo correspondences (in a truly synchronous fashion). We perform an extensive analysis on various system characteristics such as its size, catadioptric spatial resolution, field-of-view. In addition, we pose a probabilistic model for the uncertainty estimation of 3D information from triangulation of back-projected rays. We validate the projection error of the design using both synthetic and real-life images against ground-truth data. Qualitatively, we show 3D point clouds (dense and sparse) resulting out of a single image captured from a real-life experiment. We expect the reproducibility of our sensor as its model parameters can be optimized to satisfy other catadioptric-based omnistereo vision under different circumstances. PMID:26861351

  20. Thin films of tetrafluorosubstituted cobalt phthalocyanine: Structure and sensor properties

    NASA Astrophysics Data System (ADS)

    Klyamer, Darya D.; Sukhikh, Aleksandr S.; Krasnov, Pavel O.; Gromilov, Sergey A.; Morozova, Natalya B.; Basova, Tamara V.

    2016-05-01

    In this work, thin films of tetrafluorosubstituted cobalt phthalocyanine (CoPcF4) were prepared by organic molecular beam deposition and their structure was studied using UV-vis, polarization dependent Raman spectroscopy, XRD and atomic force microscopy. Quantum chemical calculations (DFT) have been employed in order to determine the detailed assignment of the bands in the CoPcF4 IR and Raman spectra. The electrical sensor response of CoPcF4 films to ammonia vapours was investigated and compared with that of unsubstituted cobalt phthalocyanine films. In order to explain the difference in sensitivity of the unsubstituted and fluorinated phthalocyanines to ammonia, the nature and properties of chemical binding between CoPc derivatives and NH3 were described by quantum-chemical calculations utilizing DFT method. The effect of post-deposition annealing on surface morphology and gas sensing properties of CoPcF4 films was also studied.

  1. Phase structure development as preheating UHMWPE powder temperature changes in the micro-UPM process

    NASA Astrophysics Data System (ADS)

    Liang, Xiong; Wu, Xiaoyu; Xu, Bin; Ma, Jiang; Liu, Zhiyuan; Peng, Taijiang; Fu, Lianyu

    2016-01-01

    In this study, using high-speed mechanical drilling on printed circuit boards (PCBs) with two micro carbide drill bits with diameters of 0.15 mm and 0.20 mm, two different PCB micro-cylinder array inserts are fabricated using the micro-ultrasonic powder moulding (micro-UPM) process. According to the temperature curves recorded by a measurement module, when viscoelastic heating dominated, the temperature increasing rate was about three times the rate when interfacial friction heating dominated. From the differential scanning calorimetry and nanoindentation test results, if the ultra-high molecule weight polyethylene (UHMWPE) powder was not preheated, then the micro-cylinder array polymer parts generally consisted of nascent and melt-recrystallised phases as a whole. However, when the micro-cavity and compressed UHMWPE powder grew from room temperature of 28 °C to 85 °C, the two-phase structure gradually developed into a single melt-recrystallised phase. According to single-crystal x-ray diffraction test results, the crystallinity of the base region of the micro-UPM cylinder array part is higher than that of the micro-cylinder region, whereas the grain size of the (1 1 0) crystal surface is larger than that of the (2 0 0) crystal surface.

  2. Hierarchical assembly of micro-/nano-building blocks: bio-inspired rigid structural functional materials.

    PubMed

    Yao, Hong-Bin; Fang, Hai-Yu; Wang, Xiao-Han; Yu, Shu-Hong

    2011-07-01

    The huge diversity of hierarchical micro-/nano-rigid structures existing in biological systems is increasingly becoming a source of inspiration of materials scientists and engineers to create next-generation advanced functional materials. In the past decades, these multiscale hierarchical structures have been intensively investigated to show their contributions to high performance in mechanical properties. Recently, accompanied with the development of nanotechnology, some biologically hierarchical rigid structures have been duplicated and mimicked in artificial materials through hierarchical organization of micro-/nano-building blocks. In this critical review, we will present biological rigid structural models, functional micro-/nano-building blocks, and hierarchical assembly techniques for the manufacture of bio-inspired rigid structural functional materials (177 references).

  3. Fabrication of micro/nano hierarchical structures with analysis on the surface mechanics

    NASA Astrophysics Data System (ADS)

    Jheng, Yu-Sheng; Lee, Yeeu-Chang

    2016-10-01

    Biomimicry refers to the imitation of mechanisms and features found in living creatures using artificial methods. This study used optical lithography, colloidal lithography, and dry etching to mimic the micro/nano hierarchical structures covering the soles of gecko feet. We measured the static contact angle and contact angle hysteresis to reveal the behavior of liquid drops on the hierarchical structures. Pulling tests were also performed to measure the resistance of movement between the hierarchical structures and a testing plate. Our results reveal that hierarchical structures at the micro-/nano-scale are considerably hydrophobic, they provide good flow characteristics, and they generate more contact force than do surfaces with micro-scale cylindrical structures.

  4. Comprehensive and Critical Literature Review on Insitu Micro-Sensors for Application in Tribology

    DTIC Science & Technology

    1994-04-01

    application: automotive versus industrial, manifold absolute pressure versus blood pressure . Both of these particular examples utilize micromachined... pressure transducer. The requirements are a 90-100 ps.i. pgae sensor which can sustain a high-shock, shipboard environment. Fig. 4 shows schematically...placed for ease of repair. For a robust system, a Bourdon tube mechanism, to which quartz crystal is attached, is used. These mechanisms allow the pressure

  5. Micro-encapsulated sensors for in vivo assessment of the oxidative stress in aquatic organisms

    NASA Astrophysics Data System (ADS)

    Sadovoy, Anton; Teh, Cathleen; Escobar, Marco; Meglinski, Igor; Korzh, Vladimir

    2012-03-01

    Oxidative stress results from an imbalance between the production and detoxification of reactive oxygen spices (ROS). ROS are natural byproducts of normal metabolism of oxygen and have important roles in cell signaling and homeostasis. Many heart related diseases like heart failure and myocardial infarction develop as a result of oxidative stress. Current treatment cannot improve the progressive decline in heart function experienced by all patients. Therefore heart failure is the cause of around 25% of all deaths in the Asia Pacific region. Thus any step taken to address the oxidative stress problem is essential for enhancing human health and improve their quality of life. Current approach is dedicated to develop micron-size oxidation stress-sensor for in-vivo measuring level of ROS in KillerRed expressing transgenic zebrafish larvae. Central to our investigation is the light-inducible heart failure animal model we developed in zebrafish that expressed KillerRed in the heart. By utilizing the photosensitizer properties of KillerRed to produce ROS upon green light illumination, heart failure can be repeatedly induced in a non-invasive manner. Importantly, the use of this biological platform permits the development of physiologically sensitive ROS sensor and identifies efficient antioxidants that improve heart contractility. The biosensor approach is based on utilizing biocompatible polyelectrolyte microcapsules as a carry of fluorescent dyes sensitive to amount of reactive oxygen spices. Microcapsule prevents dye diffusion in tissue that makes use toxic dyes possible. Microcapsule's wall is permeable for environment with size less than 500 Da. The oxidation stress-sensors are injected directly in zebrafish pericardium with further circulation along blood system. Detecting of ROS is obtained by using laser scanning microscopy by illuminating oxidation stress-sensors and detecting changing excitation signal from the fluorescent dye.

  6. Micro-encapsulated sensors for in vivo assessment of the oxidative stress in aquatic organisms

    NASA Astrophysics Data System (ADS)

    Sadovoy, Anton; Teh, Cathleen; Escobar, Marco; Meglinski, Igor; Korzh, Vladimir

    2011-10-01

    Oxidative stress results from an imbalance between the production and detoxification of reactive oxygen spices (ROS). ROS are natural byproducts of normal metabolism of oxygen and have important roles in cell signaling and homeostasis. Many heart related diseases like heart failure and myocardial infarction develop as a result of oxidative stress. Current treatment cannot improve the progressive decline in heart function experienced by all patients. Therefore heart failure is the cause of around 25% of all deaths in the Asia Pacific region. Thus any step taken to address the oxidative stress problem is essential for enhancing human health and improve their quality of life. Current approach is dedicated to develop micron-size oxidation stress-sensor for in-vivo measuring level of ROS in KillerRed expressing transgenic zebrafish larvae. Central to our investigation is the light-inducible heart failure animal model we developed in zebrafish that expressed KillerRed in the heart. By utilizing the photosensitizer properties of KillerRed to produce ROS upon green light illumination, heart failure can be repeatedly induced in a non-invasive manner. Importantly, the use of this biological platform permits the development of physiologically sensitive ROS sensor and identifies efficient antioxidants that improve heart contractility. The biosensor approach is based on utilizing biocompatible polyelectrolyte microcapsules as a carry of fluorescent dyes sensitive to amount of reactive oxygen spices. Microcapsule prevents dye diffusion in tissue that makes use toxic dyes possible. Microcapsule's wall is permeable for environment with size less than 500 Da. The oxidation stress-sensors are injected directly in zebrafish pericardium with further circulation along blood system. Detecting of ROS is obtained by using laser scanning microscopy by illuminating oxidation stress-sensors and detecting changing excitation signal from the fluorescent dye.

  7. Specifically and wash-free labeling of SNAP-tag fused proteins with a hybrid sensor to monitor local micro-viscosity.

    PubMed

    Wang, Chao; Song, Xinbo; Chen, Lingcheng; Xiao, Yi

    2017-05-15

    Viscosity, as one of the major factors of intracellular microenvironment, influences the function of proteins. To detect local micro-viscosity of a protein, it is a precondition to apply a viscosity sensor for specifically target to proteins. However, all the reported small-molecule probes are just suitable for sensing/imaging of macro-viscosity in biological fluids of entire cells or organelles. To this end, we developed a hybrid sensor BDP-V BG by connecting a viscosity-sensitive boron-dipyrromethene (BODIPY) molecular rotor (BDP-V) to O(6)-benzylguanine (BG) for specific detection of local micro-viscosity of SNAP-tag fused proteins. We measured and calculated the reaction efficiency between the sensor and SNAP-tag protein in vitro to confirm the high labeling specificity. We also found that the labeling reaction results in a 53-fold fluorescence enhancement for the rotor, which qualifies it as a wash-free sensor with ignorable background fluorescence. The high sensitivity of protein labeled sensor (BDP-V-SNAP) to the changes of local viscosity was evaluated by detecting the enhancement of fluorescence lifetimes. Further, with the sensor BDP-V BG, we achieved high specific labeling of cells expressing two SNAP-tag fused proteins (nuclear histone H2B and mitochondrial COX8A). Two-photon excited fluorescence lifetime imaging revealed that, the micro-viscosities nearby the SNAP-tag fused two proteins are distinct. The different changes of local micro-viscosity of SNAP-tag fused histone protein in apoptosis induced by three nucleus-targeted drugs were also characterized for the first time.

  8. Pore- and micro-structural characterization of a novel structural binder based on iron carbonation

    SciTech Connect

    Das, Sumanta; Stone, David; Convey, Diana; Neithalath, Narayanan

    2014-12-15

    The pore- and micro-structural features of a novel binding material based on the carbonation of waste metallic iron powder are reported in this paper. The binder contains metallic iron powder as the major ingredient, followed by additives containing silica and alumina to facilitate favorable reaction product formation. Compressive strengths sufficient for a majority of concrete applications are attained. The material pore structure is investigated primarily through mercury intrusion porosimetry whereas electron microscopy is used for microstructural characterization. Reduction in the overall porosity and the average pore size with an increase in carbonation duration from 1 day to 4 days is noticed. The pore structure features are used in predictive models for gas and moisture transport (water vapor diffusivity and moisture permeability) through the porous medium which dictates its long-term durability when used in structural applications. Comparisons of the pore structure with those of a Portland cement paste are also provided. The morphology of the reaction products in the iron-based binder, and the distribution of constituent elements in the microstructure are also reported. - Highlights: • Carbonation of iron produces a dense microstructure. • Pore volume in iron carbonate lower, critical size higher than those in OPC pastes • Reaction product contains iron, carbon, silicon, aluminum and calcium. • Power-law for porosity-moisture permeability relationship was established.

  9. Structural Health Monitoring Using Textile Reinforcement Structures with Integrated Optical Fiber Sensors.

    PubMed

    Bremer, Kort; Weigand, Frank; Zheng, Yulong; Alwis, Lourdes Shanika; Helbig, Reinhard; Roth, Bernhard

    2017-02-10

    Optical fiber-based sensors "embedded" in functionalized carbon structures (FCSs) and textile net structures (TNSs) based on alkaline-resistant glass are introduced for the purpose of structural health monitoring (SHM) of concrete-based structures. The design aims to monitor common SHM parameters such as strain and cracks while at the same time acting as a structural strengthening mechanism. The sensor performances of the two systems are characterized in situ using Mach-Zehnder interferometric (MZI) and optical attenuation measurement techniques, respectively. For this purpose, different FCS samples were subjected to varying elongation using a tensile testing machine by carefully incrementing the applied force, and good correlation between the applied force and measured length change was observed. For crack detection, the functionalized TNSs were embedded into a concrete block which was then exposed to varying load using the three-point flexural test until destruction. Promising results were observed, identifying that the location of the crack can be determined using the conventional optical time domain reflectometry (OTDR) technique. The embedded sensors thus evaluated show the value of the dual achievement of the schemes proposed in obtaining strain/crack measurement while being utilized as strengthening agents as well.

  10. Structural Health Monitoring Using Textile Reinforcement Structures with Integrated Optical Fiber Sensors

    PubMed Central

    Bremer, Kort; Weigand, Frank; Zheng, Yulong; Alwis, Lourdes Shanika; Helbig, Reinhard; Roth, Bernhard

    2017-01-01

    Optical fiber-based sensors “embedded” in functionalized carbon structures (FCSs) and textile net structures (TNSs) based on alkaline-resistant glass are introduced for the purpose of structural health monitoring (SHM) of concrete-based structures. The design aims to monitor common SHM parameters such as strain and cracks while at the same time acting as a structural strengthening mechanism. The sensor performances of the two systems are characterized in situ using Mach-Zehnder interferometric (MZI) and optical attenuation measurement techniques, respectively. For this purpose, different FCS samples were subjected to varying elongation using a tensile testing machine by carefully incrementing the applied force, and good correlation between the applied force and measured length change was observed. For crack detection, the functionalized TNSs were embedded into a concrete block which was then exposed to varying load using the three-point flexural test until destruction. Promising results were observed, identifying that the location of the crack can be determined using the conventional optical time domain reflectometry (OTDR) technique. The embedded sensors thus evaluated show the value of the dual achievement of the schemes proposed in obtaining strain/crack measurement while being utilized as strengthening agents as well. PMID:28208636

  11. Structural tests using a MEMS acoustic emission sensor

    NASA Astrophysics Data System (ADS)

    Oppenheim, Irving J.; Greve, David W.; Ozevin, Didem; Hay, D. Robert; Hay, Thomas R.; Pessiki, Stephen P.; Tyson, Nathan L.

    2006-03-01

    In a collaborative project at Lehigh and Carnegie Mellon, a MEMS acoustic emission sensor was designed and fabricated as a suite of six resonant-type capacitive transducers in the frequency range between 100 and 500 kHz. Characterization studies showed good comparisons between predicted and experimental electro-mechanical behavior. Acoustic emission events, simulated experimentally in steel ball impact and in pencil lead break tests, were detected and source localization was demonstrated. In this paper we describe the application of the MEMS device in structural testing, both in laboratory and in field applications. We discuss our findings regarding housing and mounting (acoustic coupling) of the MEMS device with its supporting electronics, and we then report the results of structural testing. In all tests, the MEMS transducers were used in parallel with commercial acoustic emission sensors, which thereby serve as a benchmark and permit a direct observation of MEMS device functionality. All tests involved steel structures, with particular interest in propagation of existing cracks or flaws. A series of four laboratory tests were performed on beam specimens fabricated from two segments (Grade 50 steel) with a full penetration weld (E70T-4 electrode material) at midspan. That weld region was notched, an initial fatigue crack was induced, and the specimens were then instrumented with one commercial transducer and with one MEMS device; data was recorded from five individual transducers on the MEMS device. Under a four-point bending test, the beam displayed both inelastic behavior and crack propagation, including load drops associated with crack instability. The MEMS transducers detected all instability events as well as many or most of the acoustic emissions occurring during plasticity and stable crack growth. The MEMS transducers were less sensitive than the commercial transducer, and did not detect as many events, but the normalized cumulative burst count obtained

  12. Structural health monitoring system of soccer arena based on optical sensors

    NASA Astrophysics Data System (ADS)

    Shishkin, Victor V.; Churin, Alexey E.; Kharenko, Denis S.; Zheleznova, Maria A.; Shelemba, Ivan S.

    2014-05-01

    A structural health monitoring system based on optical sensors has been developed and installed on the indoor soccer arena "Zarya" in Novosibirsk. The system integrates 119 fiber optic sensors: 85 strain, 32 temperature and 2 displacement sensors. In addition, total station is used for measuring displacement in 45 control points. All of the constituents of the supporting structure are subjects for monitoring: long-span frames with under floor ties, connections, purlins and foundation.

  13. The effect of prediction error correlation on optimal sensor placement in structural dynamics

    NASA Astrophysics Data System (ADS)

    Papadimitriou, Costas; Lombaert, Geert

    2012-04-01

    The problem of estimating the optimal sensor locations for parameter estimation in structural dynamics is re-visited. The effect of spatially correlated prediction errors on the optimal sensor placement is investigated. The information entropy is used as a performance measure of the sensor configuration. The optimal sensor location is formulated as an optimization problem involving discrete-valued variables, which is solved using computationally efficient sequential sensor placement algorithms. Asymptotic estimates for the information entropy are used to develop useful properties that provide insight into the dependence of the information entropy on the number and location of sensors. A theoretical analysis shows that the spatial correlation length of the prediction errors controls the minimum distance between the sensors and should be taken into account when designing optimal sensor locations with potential sensor distances up to the order of the characteristic length of the dynamic problem considered. Implementation issues for modal identification and structural-related model parameter estimation are addressed. Theoretical and computational developments are illustrated by designing the optimal sensor configurations for a continuous beam model, a discrete chain-like stiffness-mass model and a finite element model of a footbridge in Wetteren (Belgium). Results point out the crucial effect the spatial correlation of the prediction errors have on the design of optimal sensor locations for structural dynamics applications, revealing simultaneously potential inadequacies of spatially uncorrelated prediction errors models.

  14. Propulsion of micro-structures in Oscillatory Stokes Flow

    NASA Astrophysics Data System (ADS)

    Jo, Ikhee; Huang, Yangyang; Zimmerman, Walter; Kanso, Eva

    2015-11-01

    Drug delivery often necessitates specific site-targeting within the human body. The use of micro and/or nano devices swimming through the bloodstream provides an attractive mechanism for targeted drug targeting, however the design and practical implementation of such devices remain very challenging. Inspired by flapping wings, we construct a two-dimensional wedge-like device, consisting of two links connected by a linear torsional spring and released in an oscillatory Stokes flow. We vary the stiffness and rest angle of the linear spring and the oscillation amplitude and frequency of the background flow to explore the behavior of the device. We find that the device achieves a net displacement, or propulsion, in oscillatory flows even when no elastic energy is stored initially, thus breaking Purcell's scallop's theorem. More importantly, the vehicle tends to align with the background flow under perturbations. We conclude by commenting on how to control the parameters of the device and the fluid to achieve desired behavior of the device. These findings may have significant implications on the design of micro devices in viscous fluids.

  15. Choosing Sensor Configuration for a Flexible Structure Using Full Control Synthesis

    NASA Technical Reports Server (NTRS)

    Lind, Rick; Nalbantoglu, Volkan; Balas, Gary

    1997-01-01

    Optimal locations and types for feedback sensors which meet design constraints and control requirements are difficult to determine. This paper introduces an approach to choosing a sensor configuration based on Full Control synthesis. A globally optimal Full Control compensator is computed for each member of a set of sensor configurations which are feasible for the plant. The sensor configuration associated with the Full Control system achieving the best closed-loop performance is chosen for feedback measurements to an output feedback controller. A flexible structure is used as an example to demonstrate this procedure. Experimental results show sensor configurations chosen to optimize the Full Control performance are effective for output feedback controllers.

  16. Monitoring of Structural Integrity of Composite Structures by Embedded Optical Fiber Sensors

    NASA Technical Reports Server (NTRS)

    Osei, Albert J.

    2002-01-01

    Real time monitoring of the mechanical integrity and stresses on key aerospace composite structures like aircraft wings, walls of pressure vessels and fuel tanks or any other structurally extended components and panels as in space telescopes is very important to NASA. Future military and commercial aircraft as well as NASA space systems such as Space Based Radar and International Space Station will incorporate a monitoring system to sense any degradation to the structure. In the extreme flight conditions of an aerospace vehicle it might be desirable to measure the strain every ten centimeters and thus fully map out the strain field of a composite component. A series of missions and vehicle health management requirements call for these measurements. At the moment thousands of people support a few vehicle launches per year. This number can be significantly reduced by implementing intelligent vehicles with integral nervous systems (smart structures). This would require maintenance to be performed only as needed. Military and commercial aircrafts have an equally compelling case. Maintenance yearly costs are currently reaching astronomical heights. Monitoring techniques are therefore required that allow for maintenance to be performed only when needed. This would allow improved safety by insuring that necessary tasks are performed while reducing costs by eliminating procedures that are costly and not needed. The advantages fiber optical sensors have over conventional electro-mechanical systems like strain gauges have been widely extolled in the research literature. These advantages include their small size, low weight, immunity to electrical resistance, corrosion resistance, compatibility with composite materials and process conditions, and multiplexing capabilities. One fiber optic device which is suitable for distributed sensing is the fiber Bragg grating (FBG). Researchers at NASA MSFC are currently developing techniques for using FBGs for monitoring the integrity of

  17. Direction-sensitive smart monitoring of structures using heterogeneous smartphone sensor data and coordinate system transformation

    NASA Astrophysics Data System (ADS)

    Ozer, Ekin; Feng, Maria Q.

    2017-04-01

    Mobile, heterogeneous, and smart sensor networks produce pervasive structural health monitoring (SHM) information. With various embedded sensors, smartphones have emerged to innovate SHM by empowering citizens to serve as sensors. By default, smartphones meet the fundamental smart sensor criteria, thanks to the built-in processor, memory, wireless communication units and mobile operating system. SHM using smartphones, however, faces technical challenges due to citizen-induced uncertainties, undesired sensor-structure integration, and lack of control over the sensing platform. Previously, the authors presented successful applications of smartphone accelerometers for structural vibration measurement and proposed a monitoring framework under citizen-induced spatiotemporal uncertainties. This study aims at extending the capabilities of smartphone-based SHM with a special focus on the lack of control over the sensor (i.e., the phone) positioning by citizens resulting in unknown sensor orientations. Using smartphone gyroscope, accelerometer, and magnetometer; instantaneous sensor orientation can be obtained with respect to gravitational and magnetic north directions. Using these sensor data, mobile operating system frameworks return processed features such as attitude and heading that can be used to correct misaligned sensor signals. For this purpose, a coordinate transformation procedure is proposed and illustrated on a two-story laboratory structural model and real-scale bridges with various sensor positioning examples. The proposed method corrects the sensor signals by tracking their orientations and improves measurement accuracy. Moreover, knowing structure’s coordinate system a priori, even the data from arbitrarily positioned sensors can automatically be transformed to the structural coordinates. In addition, this paper also touches some secondary mobile and heterogeneous data issues including imperfect sampling and geolocation services. The coordinate system

  18. In-Situ Measurement of High-Temperature Proton Exchange Membrane Fuel Cell Stack Using Flexible Five-in-One Micro-Sensor.

    PubMed

    Lee, Chi-Yuan; Weng, Fang-Bor; Kuo, Yzu-Wei; Tsai, Chao-Hsuan; Cheng, Yen-Ting; Cheng, Chih-Kai; Lin, Jyun-Ting

    2016-10-18

    In the chemical reaction that proceeds in a high-temperature proton exchange membrane fuel cell stack (HT-PEMFC stack), the internal local temperature, voltage, pressure, flow and current nonuniformity may cause poor membrane material durability and nonuniform fuel distribution, thus influencing the performance and lifetime of the fuel cell stack. In this paper micro-electro-mechanical systems (MEMS) are utilized to develop a high-temperature electrochemical environment-resistant five-in-one micro-sensor embedded in the cathode channel plate of an HT-PEMFC stack, and materials and process parameters are appropriately selected to protect the micro-sensor against failure or destruction during long-term operation. In-situ measurement of the local temperature, voltage, pressure, flow and current distributions in the HT-PEMFC stack is carried out. This integrated micro-sensor has five functions, and is favorably characterized by small size, good acid resistance and temperature resistance, quick response, real-time measurement, and the goal is being able to be put in any place for measurement without affecting the performance of the battery.

  19. In-Situ Measurement of High-Temperature Proton Exchange Membrane Fuel Cell Stack Using Flexible Five-in-One Micro-Sensor

    PubMed Central

    Lee, Chi-Yuan; Weng, Fang-Bor; Kuo, Yzu-Wei; Tsai, Chao-Hsuan; Cheng, Yen-Ting; Cheng, Chih-Kai; Lin, Jyun-Ting

    2016-01-01

    In the chemical reaction that proceeds in a high-temperature proton exchange membrane fuel cell stack (HT-PEMFC stack), the internal local temperature, voltage, pressure, flow and current nonuniformity may cause poor membrane material durability and nonuniform fuel distribution, thus influencing the performance and lifetime of the fuel cell stack. In this paper micro-electro-mechanical systems (MEMS) are utilized to develop a high-temperature electrochemical environment-resistant five-in-one micro-sensor embedded in the cathode channel plate of an HT-PEMFC stack, and materials and process parameters are appropriately selected to protect the micro-sensor against failure or destruction during long-term operation. In-situ measurement of the local temperature, voltage, pressure, flow and current distributions in the HT-PEMFC stack is carried out. This integrated micro-sensor has five functions, and is favorably characterized by small size, good acid resistance and temperature resistance, quick response, real-time measurement, and the goal is being able to be put in any place for measurement without affecting the performance of the battery. PMID:27763559

  20. Proton currents constrain structural models of voltage sensor activation

    PubMed Central

    Randolph, Aaron L; Mokrab, Younes; Bennett, Ashley L; Sansom, Mark SP; Ramsey, Ian Scott

    2016-01-01

    The Hv1 proton channel is evidently unique among voltage sensor domain proteins in mediating an intrinsic ‘aqueous’ H+ conductance (GAQ). Mutation of a highly conserved ‘gating charge’ residue in the S4 helix (R1H) confers a resting-state H+ ‘shuttle’ conductance (GSH) in VGCs and Ci VSP, and we now report that R1H is sufficient to reconstitute GSH in Hv1 without abrogating GAQ. Second-site mutations in S3 (D185A/H) and S4 (N4R) experimentally separate GSH and GAQ gating, which report thermodynamically distinct initial and final steps, respectively, in the Hv1 activation pathway. The effects of Hv1 mutations on GSH and GAQ are used to constrain the positions of key side chains in resting- and activated-state VS model structures, providing new insights into the structural basis of VS activation and H+ transfer mechanisms in Hv1. DOI: http://dx.doi.org/10.7554/eLife.18017.001 PMID:27572256

  1. A nanoporous interferometric micro-sensor for biomedical detection of volatile sulphur compounds

    NASA Astrophysics Data System (ADS)

    Kumeria, Tushar; Parkinson, Luke; Losic, Dusan

    2011-12-01

    This work presents the use of nanoporous anodic aluminium oxide [AAO] for reflective interferometric sensing of volatile sulphur compounds and hydrogen sulphide [H2S] gas. Detection is based on changes of the interference signal from AAO porous layer as a result of specific adsorption of gas molecules with sulphur functional groups on a gold-coated surface. A nanoporous AAO sensing platform with optimised pore diameters (30 nm) and length (4 µm) was fabricated using a two-step anodization process in 0.3 M oxalic, followed by coating with a thin gold film (8 nm). The AAO is assembled in a specially designed microfluidic chip supported with a miniature fibre optic system that is able to measure changes of reflective interference signal (Fabry-Perrot fringes). When the sensor is exposed to a small concentration of H2S gas, the interference signal showed a concentration-dependent wavelength shifting of the Fabry-Perot interference fringe spectrum, as a result of the adsorption of H2S molecules on the Au surface and changes in the refractive index of the AAO. A practical biomedical application of reflectometric interference spectroscopy [RIfS] Au-AAO sensor for malodour measurement was successfully shown. The RIfS method based on a nanoporous AAO platform is simple, easy to miniaturise, inexpensive and has great potential for development of gas sensing devices for a range of medical and environmental applications.

  2. Turbidity Sensor for Bacterial Growth Measurements in Spaceflight and Simulated Micro-gravity

    NASA Astrophysics Data System (ADS)

    van Benthem, Roel; de Grave, Wubbo

    2009-11-01

    For the BIOFILTER flight experiment a set of turbidity sensors was developed for the measurement of the growth rate of the bacteria Xanthobacter autrophicus GJ10 in a fluid medium. During the flight experiment on FOTON M2 in 2005, bacterial growth was measured revealing growth rates between 0.046-0.077 h - 1 in microgravity, i.e. approximately 1.5-2.5 times slower than routinely measured under optimal laboratory conditions on earth. To increase confidence in the equipment and for comparison of the results, a ground-reference experiment was carried out in 2006, using BIOFILTER hardware mounted on a random positioning machine (RPM). The RPM performed random rotations at 0.5°/min (for settling compensation) and 90°/min (for simulated microgravity) while the environment was controlled, accurately repeating the BIOFILTER flight temperature conditions. Despite the rotations of the RPM, a normal growth rate of 0.115 h - 1 was confirmed in both cases. The operation of the turbidity sensor was verified. Biological interpretation of the measurements is however compromised due to poor mixing and other unknown physical and biological phenomena that need to be addressed for further space experiments using these kinds of systems.

  3. A nanoporous interferometric micro-sensor for biomedical detection of volatile sulphur compounds.

    PubMed

    Kumeria, Tushar; Parkinson, Luke; Losic, Dusan

    2011-12-16

    This work presents the use of nanoporous anodic aluminium oxide [AAO] for reflective interferometric sensing of volatile sulphur compounds and hydrogen sulphide [H2S] gas. Detection is based on changes of the interference signal from AAO porous layer as a result of specific adsorption of gas molecules with sulphur functional groups on a gold-coated surface. A nanoporous AAO sensing platform with optimised pore diameters (30 nm) and length (4 µm) was fabricated using a two-step anodization process in 0.3 M oxalic, followed by coating with a thin gold film (8 nm). The AAO is assembled in a specially designed microfluidic chip supported with a miniature fibre optic system that is able to measure changes of reflective interference signal (Fabry-Perrot fringes). When the sensor is exposed to a small concentration of H2S gas, the interference signal showed a concentration-dependent wavelength shifting of the Fabry-Perot interference fringe spectrum, as a result of the adsorption of H2S molecules on the Au surface and changes in the refractive index of the AAO. A practical biomedical application of reflectometric interference spectroscopy [RIfS] Au-AAO sensor for malodour measurement was successfully shown. The RIfS method based on a nanoporous AAO platform is simple, easy to miniaturise, inexpensive and has great potential for development of gas sensing devices for a range of medical and environmental applications.

  4. A nanoporous interferometric micro-sensor for biomedical detection of volatile sulphur compounds

    PubMed Central

    2011-01-01

    This work presents the use of nanoporous anodic aluminium oxide [AAO] for reflective interferometric sensing of volatile sulphur compounds and hydrogen sulphide [H2S] gas. Detection is based on changes of the interference signal from AAO porous layer as a result of specific adsorption of gas molecules with sulphur functional groups on a gold-coated surface. A nanoporous AAO sensing platform with optimised pore diameters (30 nm) and length (4 µm) was fabricated using a two-step anodization process in 0.3 M oxalic, followed by coating with a thin gold film (8 nm). The AAO is assembled in a specially designed microfluidic chip supported with a miniature fibre optic system that is able to measure changes of reflective interference signal (Fabry-Perrot fringes). When the sensor is exposed to a small concentration of H2S gas, the interference signal showed a concentration-dependent wavelength shifting of the Fabry-Perot interference fringe spectrum, as a result of the adsorption of H2S molecules on the Au surface and changes in the refractive index of the AAO. A practical biomedical application of reflectometric interference spectroscopy [RIfS] Au-AAO sensor for malodour measurement was successfully shown. The RIfS method based on a nanoporous AAO platform is simple, easy to miniaturise, inexpensive and has great potential for development of gas sensing devices for a range of medical and environmental applications. PMID:22176687

  5. Embeddable fiber optic strain sensor for structural monitoring

    NASA Astrophysics Data System (ADS)

    Kaur, Amardeep; Nagarajan, Sriram; Anandan, Sudharshan; Yuan, Lei; Chandrashekhara, K.; Watkins, Steve E.; Xiao, Hai; Phan, Nam

    2013-04-01

    An extrinsic Fabry-Perot interferometric (EFPI) fiber optic sensor is presented for measurement of strain at high ambient temperatures. The sensor is fabricated using a femto-second (fs) laser. The EFPI sensor is fabricated by micromachining a cavity on the tip of a standard single-mode fiber and is then self-enclosed by fusion splicing another piece of singlemode fiber. The fs-laser based fabrication makes the sensor thermally stable to sustain temperatures as high as 800 °C. The sensor is relatively insensitive towards the temperature as compared to its response towards the applied strain. The sensor can be embedded in Carbon fiber/Bismaleimide (BMI) composite laminates for strain monitoring at high ambient temperatures.

  6. Development of Maintenance Techniques of Railway Structures Applying Sensor and Information Technologies

    NASA Astrophysics Data System (ADS)

    Yamada, Seiji; Nihei, Tatsuya; Kobayashi, Yusuke; Minegishi, Kuniyuki; Nakayama, Takashi; Sato, Norio

    Maintenance of railway structures is important. However, the expense and time for inspection of the structures are large. In addition, judgments of performance of the structures depend on experience and knowledge of inspector. Therefore we have applied sensor and information technologies in order to support inspection and to improve inspection and diagnosis technologies. In this paper, we have shown mechanisms of damage outbreak and performance of sensors for five kinds of structures. Furthermore we have suggested joint-translation-angle detection device, damage detection sensor, FBG (Fiber Bragg Grating) sensor, electric conductible paint and piezoelectric element as self-sensing sensors. In addition, as non-contact transmission system, we have adopted Zig-Bee radio, RF-ID tag and specified low-power radio. By the completion of those systems, inspection systems of structures which have depended on experience and knowledge of inspector will be extensively improved and precision and certainty for inspection and diagnosis technologies are will be ensured.

  7. A new approach for structural health monitoring by applying anomaly detection on strain sensor data

    NASA Astrophysics Data System (ADS)

    Trichias, Konstantinos; Pijpers, Richard; Meeuwissen, Erik

    2014-03-01

    Structural Health Monitoring (SHM) systems help to monitor critical infrastructures (bridges, tunnels, etc.) remotely and provide up-to-date information about their physical condition. In addition, it helps to predict the structure's life and required maintenance in a cost-efficient way. Typically, inspection data gives insight in the structural health. The global structural behavior, and predominantly the structural loading, is generally measured with vibration and strain sensors. Acoustic emission sensors are more and more used for measuring global crack activity near critical locations. In this paper, we present a procedure for local structural health monitoring by applying Anomaly Detection (AD) on strain sensor data for sensors that are applied in expected crack path. Sensor data is analyzed by automatic anomaly detection in order to find crack activity at an early stage. This approach targets the monitoring of critical structural locations, such as welds, near which strain sensors can be applied during construction and/or locations with limited inspection possibilities during structural operation. We investigate several anomaly detection techniques to detect changes in statistical properties, indicating structural degradation. The most effective one is a novel polynomial fitting technique, which tracks slow changes in sensor data. Our approach has been tested on a representative test structure (bridge deck) in a lab environment, under constant and variable amplitude fatigue loading. In both cases, the evolving cracks at the monitored locations were successfully detected, autonomously, by our AD monitoring tool.

  8. Precision truss structures from concept to hardware reality: application to the Micro-Precision Interferometer Testbed

    NASA Astrophysics Data System (ADS)

    Sword, Lee F.; Carne, Thomas G.

    1993-09-01

    This paper describes the development of the truss structure at the Jet Propulsion Laboratory that forms the backbone of JPL's Micro-Precision Interferometer (MPI) Testbed. The Micro- Precision Interferometer (MPI) Testbed is the third generation of Control Structure Interaction (CSI) Testbeds constructed by JPL aimed at developing and validating control concepts. The MPI testbed is essentially a space-based Michelson interferometer suspended in a ground- based laboratory. This instrument, mounted to the flexible truss, requires nanometer level precision alignment and positioning of its optical elements to achieve science objectives. A layered control architecture, utilizing isolation, structural control, and active optical control technologies, allow the system to meet its vibration attenuation goals. Success of the structural control design, which involves replacement of truss struts with active and/or passive elements, depends heavily on high fidelity models of the structure to evaluate strut placement locations. The first step in obtaining an accurate structure model is to build a structure which is linear.

  9. Light diffusing effects of nano and micro-structures on OLED with microcavity.

    PubMed

    Cho, Doo-Hee; Shin, Jin-Wook; Joo, Chul Woong; Lee, Jonghee; Park, Seung Koo; Moon, Jaehyun; Cho, Nam Sung; Chu, Hye Yong; Lee, Jeong-Ik

    2014-10-20

    We examined the light diffusing effects of nano and micro-structures on microcavity designed OLEDs. The results of FDTD simulations and experiments showed that the pillar shaped nano-structure was more effective than the concave micro-structure for light diffusing of microcavity OLEDs. The sharp luminance distribution of the microcavity OLED was changed to near Lambertian luminance distribution by the nano-structure, and light diffusing effects increased with the height of the nano-structure. Furthermore, the nano-structure has advantages including light extraction of the substrate mode, reproducibility of manufacturing process, and minimizing pixel blur problems in an OLED display panel. The nano-structure is a promising candidate for a light diffuser, resolving the viewing angle problems in microcavity OLEDs.

  10. Effects of Micro-structure and Micro-parameters on Brazilian Tensile Strength Using Flat-Joint Model

    NASA Astrophysics Data System (ADS)

    Xu, Xueliang; Wu, Shunchuan; Gao, Yongtao; Xu, Miaofei

    2016-09-01

    It has been widely accepted that tensile strength plays a dominant role in the failure mechanism of rock or rock-like material. Tensile strength is determined mainly via two methods: the direct tension test and Brazilian test. Due to the strictness of preparing the specimen and difficulty of conducting the direct tension test, Brazilian test has been widely applied to determine the tensile strength of geo-materials. However, there is no exact standard for Brazilian test specimen. Moreover, Brazilian tensile strength (BTS) is affected by many factors, such as loading rate, loading platen width, model size. So far, most parametric studies of geo-materials have involved compression tests, but few studies have systematically focused on Brazilian test. The continuum methods have difficulty reproducing the failure process of Brazilian test, and 2D discrete element methods can not reflect the real mechanical behavior of a 3D cylindrical disk specimen. Moreover, the standard bonded-particle model has intrinsic problems in simulating geo-materials. This paper, using a 3D flat-joint model (FJM3D), investigates the effects of micro-structure and micro-parameters on BTS. The micro-structure consists of model size, model resolution, and degree of heterogeneity. The micro-parameters include the average coordination number, crack density, and bond strength. The effects on BTS are summarized, and this summary will be useful for guiding future Brazilian tests. Finally, FJM3D is used to calibrate Brisbane tuff by Brazilian test and the uniaxial compression test. The simulation results are in good agreement with those measured from experiments, and the failure process of Brazilian test is analyzed in detail at the microscale. Because of the heterogeneity of rock, cracks initiate near the loading platen instead of the center of the specimen. Even so, BTS can be an useful tensile index for geo-materials in a triaxial stress state, which is similar to the physical situations, and

  11. Acoustic emission-based sensor analysis and damage classification for structural health monitoring of composite structures

    NASA Astrophysics Data System (ADS)

    Uprety, Bibhisha

    Within the aerospace industry the need to detect and locate impact events, even when no visible damage is present, is important both from the maintenance and design perspectives. This research focused on the use of Acoustic Emission (AE) based sensing technologies to identify impact events and characterize damage modes in composite structures for structural health monitoring. Six commercially available piezoelectric AE sensors were evaluated for use with impact location estimation algorithms under development at the University of Utah. Both active and passive testing were performed to estimate the time of arrival and plate wave mode velocities for impact location estimation. Four sensors were recommended for further comparative investigations. Furthermore, instrumented low-velocity impact experiments were conducted on quasi-isotropic carbon/epoxy composite laminates to initiate specific types of damage: matrix cracking, delamination and fiber breakage. AE signal responses were collected during impacting and the test panels were ultrasonically C-scanned after impact to identify the internal damage corresponding to the AE signals. Matrix cracking and delamination damage produced using more compliant test panels and larger diameter impactor were characterized by lower frequency signals while fiber breakage produced higher frequency responses. The results obtained suggest that selected characteristics of sensor response signals can be used both to determine whether damage is produced during impacting and to characterize the types of damage produced in an impacted composite structure.

  12. Preparation of disk-like particles with micro/nano hierarchical structures.

    PubMed

    Meng, Zhen; Yang, Wenbo; Chen, Pengpeng; Wang, Weina; Jia, Xudong; Xi, Kai

    2013-10-15

    A facile, reproductive method has been successfully developed to produce disk-like microparticles self-assembled from monodispersed hybrid silica nanoparticles under certain circumstance. The disk-like microparticles with micro/nano hierarchical structures could be obtained in large amount under a mild condition and further used to biomimetic design of the superhydrophobic surface of lotus leaf. After traditional surface modification with dodecyltrichlorosiliane, the static contact angle of water on the surface with micro/nano hierarchical structure could reach 168.8°. The method of surface modification could be further simplified by click reaction with the introduction of thiol groups under mild condition. The present strategy for constructing the surface with micro/nano hierarchical structures offers the advantage of simple and large area fabrication, which enables a variety of superhydrophobic applications.

  13. Reading from Scratch - A Vision-System for Reading Data on Micro-structured Surfaces

    NASA Astrophysics Data System (ADS)

    Dragon, Ralf; Becker, Christian; Rosenhahn, Bodo; Ostermann, Jörn

    Labeling and marking industrial manufactured objects gets increasingly important nowadays because of novel material properties and plagiarism. As part of the Collaborative Research Center 653 which investigates micro-structured metallic surfaces for inherent mechanical data storage, we research into a stable and reliable optical readout of the written data. Since this comprises a qualitative surface reconstruction, we use directed illumination to make the micro structures visible. Then we apply a spectral analysis to obtain image partitioning and perform signal tracking enhanced by a customized Hidden Markov Model. In this paper, we derive the algorithms used and demonstrate reading data from a surface with 1.6kbit/cm2 from a micro-structured groove which varies by only 3μ m in depth (thus a “scratch”). We demonstrate the system’s robustness with experiments with real and artificially-rendered surfaces.

  14. Micro-structural integrity of dental enamel subjected to two tooth whitening regimes.

    PubMed

    Tanaka, Reina; Shibata, Yo; Manabe, Atsufumi; Miyazaki, Takashi

    2010-04-01

    Colour modification of tooth enamel has proven successful, but it is unclear how various bleaching applications affect micro-structural integrity of the whitened enamel. To investigate the internal structural integrity of human intact tooth enamel with the application of two commonly used whitening regimes (in-office power bleaching with 35% hydrogen peroxide and home bleaching with 10% carbamide peroxide), evaluations were performed on teeth of identical colour classification. After the bleaching applications, the enamel mineral density was quantified and visualised with micro-computed tomography. The micro-structural differences between the whitened tooth enamel samples were distinctive, though the colour parameter changes within the samples were equivalent. Home bleaching achieved colour modification by demineralisation, whereas in-office bleaching depended on redistribution of the minerals after treatment and subsequent enhanced mineralisation.

  15. Optical fiber load sensor based on a semi-auxetic structure: a proof of concept

    NASA Astrophysics Data System (ADS)

    Schenato, Luca; Pasuto, Alessandro; Galtarossa, Andrea; Palmieri, Luca

    2016-05-01

    In this work a quasi-distributed optical fiber load sensor based on a semi-auxetic structure is presented. By concatenating sections with positive Poisson's ratio to sections with negative one it is possible to precisely encode the distributed load into a strain exerted on a fiber. The sensor is described and a simple proof of concept is built and tested. The fiber is interrogated by means of optical frequency domain reflectometry. The proposed sensor represents just one example of the potential applications of auxetic and semi-auxetic structures and materials in optical fiber sensors development.

  16. Micro-displacement sensor with multimode fused coupler and concave mirror

    NASA Astrophysics Data System (ADS)

    Harun, S. W.; Yasin, M.; Ahmad, H.

    2011-04-01

    Fiber optic displacement sensor is demonstrated using a multimode fused coupler probe and a concave mirror target. It is observed that a focal length of the concave mirror make a significant influence to the displacement response, which illustrates three linear slopes with the second slope peaks at the position that is in vicinity of two times of the focal length. The highest sensitivity of 0.56 mV/mm is obtained with an infinity focal length and it is decreased as the focal length of the concave mirror decreases. The widest linear range of approximately 3.3 mm is observed in the third slope region with focal length of 6.0 mm. The highest linear range obtained with the use of 50:50 coupler.

  17. Non-contact passive temperature measuring system and method of operation using micro-mechanical sensors

    SciTech Connect

    2000-04-18

    A non-contact infrared thermometer measures target temperatures remotely without requiring the ratio of the target size to the target distance to the thermometer. A collection means collects and focuses target IR radiation on an IR detector. The detector measures thermal energy of the target over a spectrum using micromechanical sensors. A processor means calculates the collected thermal energy in at least two different spectral regions using a first algorithm in program form and further calculates the ratio of the thermal energy in the at least two different spectral regions to obtain the target temperature independent of the target size, distance to the target and emissivity using a second algorithm in program form.

  18. Non-contact passive temperature measuring system and method of operation using micro-mechanical sensors

    DOEpatents

    Thundat, Thomas G.; Oden, Patrick I.; Datskos, Panagiotis G.

    2000-01-01

    A non-contact infrared thermometer measures target temperatures remotely without requiring the ratio of the target size to the target distance to the thermometer. A collection means collects and focusses target IR radiation on an IR detector. The detector measures thermal energy of the target over a spectrum using micromechanical sensors. A processor means calculates the collected thermal energy in at least two different spectral regions using a first algorithm in program form and further calculates the ratio of the thermal energy in the at least two different spectral regions to obtain the target temperature independent of the target size, distance to the target and emissivity using a second algorithm in program form.

  19. Use of Multi-Functional Flexible Micro-Sensors for in situ Measurement of Temperature, Voltage and Fuel Flow in a Proton Exchange Membrane Fuel Cell

    PubMed Central

    Lee, Chi-Yuan; Chan, Pin-Cheng; Lee, Chung-Ju

    2010-01-01

    Temperature, voltage and fuel flow distribution all contribute considerably to fuel cell performance. Conventional methods cannot accurately determine parameter changes inside a fuel cell. This investigation developed flexible and multi-functional micro sensors on a 40 μm-thick stainless steel foil substrate by using micro-electro-mechanical systems (MEMS) and embedded them in a proton exchange membrane fuel cell (PEMFC) to measure the temperature, voltage and flow. Users can monitor and control in situ the temperature, voltage and fuel flow distribution in the cell. Thereby, both fuel cell performance and lifetime can be increased. PMID:22163545

  20. Use of multi-functional flexible micro-sensors for in situ measurement of temperature, voltage and fuel flow in a proton exchange membrane fuel cell.

    PubMed

    Lee, Chi-Yuan; Chan, Pin-Cheng; Lee, Chung-Ju

    2010-01-01

    Temperature, voltage and fuel flow distribution all contribute considerably to fuel cell performance. Conventional methods cannot accurately determine parameter changes inside a fuel cell. This investigation developed flexible and multi-functional micro sensors on a 40 μm-thick stainless steel foil substrate by using micro-electro-mechanical systems (MEMS) and embedded them in a proton exchange membrane fuel cell (PEMFC) to measure the temperature, voltage and flow. Users can monitor and control in situ the temperature, voltage and fuel flow distribution in the cell. Thereby, both fuel cell performance and lifetime can be increased.

  1. Hierarchical periodic micro/nano-structures on nitinol and their influence on oriented endothelialization and anti-thrombosis.

    PubMed

    Nozaki, Kosuke; Shinonaga, Togo; Ebe, Noriko; Horiuchi, Naohiro; Nakamura, Miho; Tsutsumi, Yusuke; Hanawa, Takao; Tsukamoto, Masahiro; Yamashita, Kimihiro; Nagai, Akiko

    2015-12-01

    The applications of hierarchical micro/nano-structures, which possess properties of two-scale roughness, have been studied in various fields. In this study, hierarchical periodic micro/nano-structures were fabricated on nitinol, an equiatomic Ni-Ti alloy, using a femtosecond laser for the surface modification of intravascular stents. By controlling the laser fluence, two types of surfaces were developed: periodic nano- and micro/nano-structures. Evaluation of water contact angles indicated that the nano-surface was hydrophilic and the micro/nano-surface was hydrophobic. Endothelial cells aligned along the nano-structures on both surfaces, whereas platelets failed to adhere to the micro/nano-surface. Decorrelation between the responses of the two cell types and the results of water contact angle analysis were a result of the pinning effect. This is the first study to show the applicability of hierarchical periodic micro/nano-structures for surface modification of nitinol.

  2. A new method to integrate ZnO nano-tetrapods on MEMS micro-hotplates for large scale gas sensor production

    NASA Astrophysics Data System (ADS)

    Marasso, S. L.; Tommasi, A.; Perrone, D.; Cocuzza, M.; Mosca, R.; Villani, M.; Zappettini, A.; Calestani, D.

    2016-09-01

    A new method, which is easily scalable to large scale production, has been developed to obtain gas sensor devices based on zinc oxide (ZnO) nanostructures with a ‘tetrapod’ shape. The method can be easily extended to other kinds of nanostructures and is based on the deposition of ZnO nanostructures through polymeric masks by centrifugation, directly onto properly designed MEMS micro-hotplates. The micromachined devices, after the mask is peeled off, are ready for electrical bonding and sensing test. Sensor response has been successfully measured for some gases and volatile organic compounds with different chemical properties (ethanol, methane, nitrogen dioxide, hydrogen sulfide).

  3. High light extraction efficiency LEDs with asymmetric obtuse angle micro-structured roofs

    NASA Astrophysics Data System (ADS)

    Chen, Chang-Jiang; Chao, Ju-Hung; Zhu, Wenbin; Yin, Stuart

    2016-09-01

    This study reports a high light extraction efficiency (LEE) light emitting diode (LED) by harnessing asymmetric obtuse angle micro-structured roofs. In comparison to conventional symmetric micro-structured roofs, the LEE has been improved from 62% to 73%. This represents an 11% improvement in LEE, which is significant for LED. It is speculated that this improvement is largely due to the increased surface area and better randomization on the direction of transmitted/reflected light, which enhances the escaping probability after multiple reflections.

  4. Study on micro-structure and morphological evolution of Fe/Pt nano-magnetic film.

    PubMed

    Ishiguro, S; Ju, D Y; Ogatsu, R; Nakano, T

    2011-10-01

    One of the vertical magnetic recordings medium materials of the hard disk drive (HDD) is a Fe/Pt thin film. The development of ultra-high density magnetic recording medium in next generation is expected the magnetic disks such as HDD with capacity enlargement of the data. In order to study effectiveness of the proposed sputtering method, we evaluated micro structure, magnetic and the mechanical properties of a Fe/Pt thin film by some sputtering process conditions. From research results, effect sputtering conditions on micro-structure and mechanical properties of Fe/Pt nano film are verified.

  5. Superplasticity of nickel-based alloys with micro- and sub-microcrystalline structures

    SciTech Connect

    Valitov, V.A.; Bewlay, B.P.; Mukhtarov, S.K.; Kaibyshev, O.A.; Gigliotti, M.F.X.

    2000-07-01

    This paper describes the generation of micro- and sub-microcrystalline structures in two Ni-based alloys that are typically strengthened by phases, such as {gamma}{prime} and {gamma}{double_prime}+{delta}. The relationship between the superplastic behavior and microstructure is discussed. High strain deformation processing in the temperature range of 0.9T{sub m} to 0.6T{sub m} results in reduction of the initial coarse-grained structure (> 100 {micro}m) to a range of structures including microcrystalline (MC) (grain size < 10 {micro}m) and sub-microcrystalline (SMC) (grain size < 1 {micro}m) with increasing deformation. The influence of alloy chemistry and constituent phases on dynamic and static recrystallization is considered, and their effect on grain refinement is described. Low-temperature and high strain rate superplasticity can be observed in dispersion-strengthened alloys with SMC structures. it was established that in dispersion-hardened Ni alloys with SMC structures, superplasticity can be observed at temperatures 200--250 C lower than in alloys with MC structure.

  6. Precise rainbow trapping for low-frequency acoustic waves with micro Mie resonance-based structures

    NASA Astrophysics Data System (ADS)

    Zhou, Chen; Yuan, Baoguo; Cheng, Ying; Liu, Xiaojun

    2016-02-01

    We have realized the acoustic rainbow trapping in the low frequency region (200-500 Hz) through micro Mie resonance-based structures. The structure has eight channels with a high refractive index obtained by coiling space, that can excite strong interactions with incident waves and support various orders of multipoles due to the Mie resonances of the microstructure. By utilizing the structure, the precise spatial modulation of the acoustic wave is demonstrated both theoretically and experimentally. The effect of trapping broadband acoustic waves and spatially separating different frequency components are ascribed to the monopolar Mie resonances of the structures. The trapping frequency is derived and the trapping positions can be tuned arbitrarily. With enhanced wave-structure interactions and tailored frequency responses, such micro structures show precise spectral-spatial control of acoustic waves and open a diverse venue for high performance acoustic wave detection, sensing, filtering, and a nondestructive test.

  7. Carbon Nanotube Based Sensor to Monitor Crack Growth in Cracked Aluminum Structures Underneath Composite Patching

    NASA Astrophysics Data System (ADS)

    Olson, T. M.; Kwon, Y. W.; Hart, D. C.; Loup, D. C.; Rasmussen, E. A.

    2015-10-01

    The paper investigates a carbon nanotube-based sensor to detect crack propagation in aluminum structures underneath composite patching. Initial tests are conducted to determine the correct procedure and materials to properly fabricate a carbon nanotube (CNT) based sensor, which is then placed in between a composite patch and the aluminum structure. The CNTs have been utilized as sensors in previous studies but only for sensing crack propagation within the composite itself. This study focuses on crack propagation in the base material and is not concerned with the composite. In this application, the composite is only a patch and can be replaced if damaged. The study conducts both tension and fatigue testing to determine the usefulness of the CNT sensor. The CNT sensor is shown to be effective in giving an indication of the crack propagation in the aluminum. Correlation is done between the crack propagation length and the increase in electrical resistance in the CNT sensor under tensile and cyclic loading, respectively.

  8. A tactile sensor using a conductive graphene-sponge composite

    NASA Astrophysics Data System (ADS)

    Chun, Sungwoo; Hong, Ahyoung; Choi, Yeonhoi; Ha, Chunho; Park, Wanjun

    2016-04-01

    For sensors that emulate human tactile perception, we suggest a simple method for fabricating a highly sensitive force sensor using a conductive polyurethane sponge where graphene flakes are self-assembled into the porous structure of the sponge. The complete sensor device shows a sensitive and reliable detection response for a broad range of pressure and dynamic pressure that correspond to human tactile perception. Sensitivity of the sensor to detect vibration is also confirmed with vertical actuations due to slipping over micro-scale ridge structures attached on the sensors. Based on the sensor's ability to detect both pressure and vibration, the sensor can be utilized as a flexible tactile sensor.For sensors that emulate human tactile perception, we suggest a simple method for fabricating a highly sensitive force sensor using a conductive polyurethane sponge where graphene flakes are self-assembled into the porous structure of the sponge. The complete sensor device shows a sensitive and reliable detection response for a broad range of pressure and dynamic pressure that correspond to human tactile perception. Sensitivity of the sensor to detect vibration is also confirmed with vertical actuations due to slipping over micro-scale ridge structures attached on the sensors. Based on the sensor's ability to detect both pressure and vibration, the sensor can be utilized as a flexible tactile sensor. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00774k

  9. Gas sensor with attenuated drift characteristic

    DOEpatents

    Chen, Ing-Shin [Danbury, CT; Chen, Philip S. H. [Bethel, CT; Neuner, Jeffrey W [Bethel, CT; Welch, James [Fairfield, CT; Hendrix, Bryan [Danbury, CT; Dimeo, Jr., Frank [Danbury, CT

    2008-05-13

    A sensor with an attenuated drift characteristic, including a layer structure in which a sensing layer has a layer of diffusional barrier material on at least one of its faces. The sensor may for example be constituted as a hydrogen gas sensor including a palladium/yttrium layer structure formed on a micro-hotplate base, with a chromium barrier layer between the yttrium layer and the micro-hotplate, and with a tantalum barrier layer between the yttrium layer and an overlying palladium protective layer. The gas sensor is useful for detection of a target gas in environments susceptible to generation or incursion of such gas, and achieves substantial (e.g., >90%) reduction of signal drift from the gas sensor in extended operation, relative to a corresponding gas sensor lacking the diffusional barrier structure of the invention

  10. Energy Harvesting for Structural Health Monitoring Sensor Networks

    SciTech Connect

    Park, G.; Farrar, C. R.; Todd, M. D.; Hodgkiss, T.; Rosing, T.

    2007-02-26

    This report has been developed based on information exchanges at a 2.5-day workshop on energy harvesting for embedded structural health monitoring (SHM) sensing systems that was held June 28-30, 2005, at Los Alamos National Laboratory. The workshop was hosted by the LANL/UCSD Engineering Institute (EI). This Institute is an education- and research-focused collaboration between Los Alamos National Laboratory (LANL) and the University of California, San Diego (UCSD), Jacobs School of Engineering. A Statistical Pattern Recognition paradigm for SHM is first presented and the concept of energy harvesting for embedded sensing systems is addressed with respect to the data acquisition portion of this paradigm. Next, various existing and emerging sensing modalities used for SHM and their respective power requirements are summarized, followed by a discussion of SHM sensor network paradigms, power requirements for these networks and power optimization strategies. Various approaches to energy harvesting and energy storage are discussed and limitations associated with the current technology are addressed. This discussion also addresses current energy harvesting applications and system integration issues. The report concludes by defining some future research directions and possible technology demonstrations that are aimed at transitioning the concept of energy harvesting for embedded SHM sensing systems from laboratory research to field-deployed engineering prototypes.

  11. A Structured Light Sensor System for Tree Inventory

    NASA Technical Reports Server (NTRS)

    Chien, Chiun-Hong; Zemek, Michael C.

    2000-01-01

    Tree Inventory is referred to measurement and estimation of marketable wood volume in a piece of land or forest for purposes such as investment or for loan applications. Exist techniques rely on trained surveyor conducting measurements manually using simple optical or mechanical devices, and hence are time consuming subjective and error prone. The advance of computer vision techniques makes it possible to conduct automatic measurements that are more efficient, objective and reliable. This paper describes 3D measurements of tree diameters using a uniquely designed ensemble of two line laser emitters rigidly mounted on a video camera. The proposed laser camera system relies on a fixed distance between two parallel laser planes and projections of laser lines to calculate tree diameters. Performance of the laser camera system is further enhanced by fusion of information induced from structured lighting and that contained in video images. Comparison will be made between the laser camera sensor system and a stereo vision system previously developed for measurements of tree diameters.

  12. Swimming of E. coli near micro-structured surfaces

    NASA Astrophysics Data System (ADS)

    Kantsler, Vasily; Dunkel, Jorn; Goldstein, Raymond E.

    2012-11-01

    Understanding the mechanisms that govern surface accumulation of swimming bacteria is a key challenge for controlling biofilm formation. Here, we report detailed measurements of density and orientation distributions for Escherichia coli bacteria as a function of the distance from a solid surface. Experiments were performed for wild-type and non-tumbling strains in both quasi-2D and 3D microfluidic chambers. We find that, for both geometries, the density profile in dilute suspensions decays sharply within a few microns from flat surfaces approaching a constant value in the bulk. Our measurements of the orientation distributions show that bacteria preserve memory of aligning collisions with surfaces for surprisingly long periods of time even after escaping into the bulk fluid. These experimental results agree well with numerical simulations of a minimal mechanistic model that accounts for steric interactions between bacteria and surfaces. We further demonstrate that optimal micro-scale surface patterning can substantially decrease accumulation of swimming bacteria, thereby providing a novel mechanism for preventing biofilm formation.

  13. Spectroscopic studies on di-pophyrin rotor as micro-viscosity sensor

    NASA Astrophysics Data System (ADS)

    Doan, H.; Raut, S.; Kimbal, J.; Gryczynski, Z.; Dzyuba, S.; Balaz, M.

    2015-03-01

    In typical biological systems the fluid compartment makes up more than 70% percent of the system weight. A variety of mass and signal transportation as well as intermolecular interactions are often governed by viscosity. It is important to be able to measure/estimate viscosity and detect the changes in viscosity upon various stimulations. Understanding the influence of changes in viscosity is crucial and development of the molecular systems that sensitive to micro-viscosity is a goal of many researches. Molecular rotors have been considered the potential target since they present enhanced sensitivity to local viscosity that can strongly restrict molecular rotation. To understand the mechanics of rotor interaction with the environment we have been studied conjugated pophyrin-dimer rotor (DP) that emit in the near IR. Our goal is to investigate the photo physical properties such as absorption, transition moment orientation, emission and excitation, polarization anisotropy and fluorescence lifetime in various mediums of different viscosities from ethanol to poly vinyl alcohol (PVA) matrices. The results imply the influences of the medium's viscosity on the two distinct confirmations: planar and twisted conformations of DP. Linear dichroism from polarized absorption in PVA matrices shows various orientations of transition moments. Excitation anisotropy shows similar transition splitting between two conformations. Time resolved intensity decay at two different observations confirms the two different emission states and furthermore the communication between the two states in the form of energy transfer upon excitation.

  14. Micro Navigator

    NASA Technical Reports Server (NTRS)

    Blaes, B. R.; Kia, T.; Chau, S. N.

    2001-01-01

    Miniature high-performance low-mass space avionics systems are desired for planned future outer planetary exploration missions (i.e. Europa Orbiter/Lander, Pluto-Kuiper Express). The spacecraft fuel and mass requirements enabling orbit insertion is the driving requirement. The Micro Navigator is an integrated autonomous Guidance, Navigation & Control (GN&C)micro-system that would provide the critical avionics function for navigation, pointing, and precision landing. The Micro Navigator hardware and software allow fusion of data from multiple sensors to provide a single integrated vehicle state vector necessary for six degrees of freedom GN&C. The benefits of this MicroNavigator include: 1) The Micro Navigator employs MEMS devices that promise orders of magnitude reductions in mass power and volume of inertial sensors (accelerometers and gyroscopes), celestial sensing devices (startracker, sun sensor), and computing element; 2) The highly integrated nature of the unit will reduce the cost of flight missions. a) The advanced miniaturization technologies employed by the Micro Navigator lend themselves to mass production, and therefore will reduce production cost of spacecraft. b) The integral approach simplifies interface issues associated with discrete components and reduces cost associated with integration and test of multiple components; and 3) The integration of sensors and processing elements into a single unit will allow the Micro Navigator to encapsulate attitude information and determination functions into a single object. This is particularly beneficial for object-oriented software architectures that are used in advanced spacecraft. Additional information is contained in the original extended abstract.

  15. Structural health monitoring of co-cured composite structures using FBG sensors

    NASA Astrophysics Data System (ADS)

    Sundaram, Ramesh; Kamath, G. M.; Gupta, Nitesh; Rao, M. Subba

    2005-05-01

    Structural Health Monitoring (SHM) of aircraft structures, especially composite structures, has assumed increased significance on considerations of safety and costs. With the advent of co-cured structures, wherein bonded joints are replacing bolted joints there is a concern regarding skin-stiffener separation, which might not be detected unless a rigorous non-destructive testing (NDT) is done. It would hence be necessary to be able to detect and assess skin-stiffener separation in composite structures before it reaches the critical size. One of the health monitoring strategies is through strain monitoring using fibre optic strain sensors such as Fibre Bragg Grating (FBG) sensors. The first aspect that needs to be addressed is the characterization of the FBG sensors. Issues of embedment in composites have also to be addressed. Before evolving a damage detection strategy, the sensitivity of the structural strain to skin-stiffener separations must be clearly understood and quantified. This paper presents the analysis and experiments done with a composite test box to study the effect of skin-stiffener separation on the strain behaviour. The box consists of two skins stiffened with spars made of Bi-Directional (BD) glass-epoxy prepreg material. The spars are bolted to the skins and removing suitable number of bolts simulates 'de-bonds'. The strains of the healthy box are compared with the unhealthy box. The strains in the experiments are monitored using both strain gauges and Fibre Bragg Grating (FBG) sensors. The experimental results show that there is significant change in the measured strain near and away from the debond location. The finite element analysis of the box is done using ABAQUS and the analysis is validated with the experimental results. A neural network based methodology is developed here to detect skin-stiffener debonds in structures. A multi-layer perceptron (MLP) neural network with a feed forward back propagation algorithm is used to determine the

  16. Structural Damage Detection with Piezoelectric Wafer Active Sensors

    NASA Astrophysics Data System (ADS)

    Giurgiutiu, Victor

    2011-07-01

    Piezoelectric wafer active sensors (PWAS) are lightweight and inexpensive enablers for a large class of damage detection and structural health monitoring (SHM) applications. This paper starts with a brief review of PWAS physical principles and basic modelling and continues by considering the various ways in which PWAS can be used for damage detection: (a) embedded guided-wave ultrasonics, i.e., pitch-catch, pulse-echo, phased arrays, thickness mode; (b) high-frequency modal sensing, i.e., the electro-mechanical (E/M) impedance method; (c) passive detection, i.e., acoustic emission and impact detection. An example of crack-like damage detection and localization with PWAS phased arrays on a small metallic plate is given. The modelling of PWAS detection of disbond damage in adhesive joints is achieved with the analytical transfer matrix method (TMM). The analytical methods offer the advantage of fast computation which enables parameter studies and carpet plots. A parametric study of the effect of crack size and PWAS location on disbond detection is presented. The power and energy transduction between PWAS and structure is studied analytically with a wave propagation method. Special attention is given to the mechatronics modeling of the complete transduction cycle from electrical excitation into ultrasonic acoustic waves by the piezoelectric effect, the transfer through the structure, and finally reverse piezoelectric transduction to generate the received electric signal. It is found that the combination of PWAS size and wave frequency/wavelength play an important role in identifying transduction maxima and minima that could be exploited to achieve an optimum power-efficient design. The multi-physics finite element method (MP-FEM), which permits fine discretization of damaged regions and complicated structural geometries, is used to study the generation of guided waves in a plate from an electrically excited transmitter PWAS and the capture of these waves as electric

  17. A Self-Powered and Autonomous Fringing Field Capacitive Sensor Integrated into a Micro Sprinkler Spinner to Measure Soil Water Content.

    PubMed

    da Costa, Eduardo Ferreira; de Oliveira, Nestor E; Morais, Flávio J O; Carvalhaes-Dias, Pedro; Duarte, Luis Fernando C; Cabot, Andreu; Siqueira Dias, J A

    2017-03-12

    We present here the design and fabrication of a self-powered and autonomous fringing field capacitive sensor to measure soil water content. The sensor is manufactured using a conventional printed circuit board and includes a porous ceramic. To read the sensor, we use a circuit that includes a 10 kHz triangle wave generator, an AC amplifier, a precision rectifier and a microcontroller. In terms of performance, the sensor's capacitance (measured in a laboratory prototype) increases up to 5% when the volumetric water content of the porous ceramic changed from 3% to 36%, resulting in a sensitivity of S = 15.5 pF per unity change. Repeatability tests for capacitance measurement showed that the θ v sensor's root mean square error is 0.13%. The average current consumption of the system (sensor and signal conditioning circuit) is less than 1.5 μ A, which demonstrates its suitability for being powered by energy harvesting systems. We developed a complete irrigation control system that integrates the sensor, an energy harvesting module composed of a microgenerator installed on the top of a micro sprinkler spinner, and a DC/DC converter circuit that charges a 1 F supercapacitor. The energy harvesting module operates only when the micro sprinkler spinner is irrigating the soil, and the supercapacitor is fully charged to 5 V in about 3 h during the first irrigation. After the first irrigation, with the supercap fully charged, the system can operate powered only by the supercapacitor for approximately 23 days, without any energy being harvested.

  18. Continuous monitoring of large civil structures using a digital fiber optic motion sensor system

    NASA Astrophysics Data System (ADS)

    Hodge, Malcolm H.; Kausel, Theodore C., Jr.

    1998-03-01

    There is no single attribute which can always predict structural deterioration. Accordingly, we have developed a scheme for monitoring a wide range of incipient deterioration parameters, all based on a single motion sensor concept. In this presentation, we describe how an intrinsically low power- consumption fiber optic harness can be permanently deployed to poll an array of optical sensors. The function and design of these simple, durable, and naturally digital sensors is described, along with the manner in which they have been configured to collect information for changes in the most important structural aspects. The SIMS system is designed to interrogate each sensor up to five-thousand times per second for the life of the structure, and to report sensor data back to a remote computer base for current and long-term analysis, and is directed primarily towards bridges. By suitably modifying the actuation of this very precise motion sensor, SIMS is able to track bridge deck deflection and vibration, expansion joint travel, concrete and rebar corrosion, pothole development, pier scour and tilt. Other sensors will track bolt clamp load, cable tension, and metal fatigue. All of these data are received within microseconds, which means that appropriate computer algorithm manipulations can be carried out to correlate one sensor with other sensors in real time. This internal verification feature automatically enhances confidence in the system's predictive ability and alerts the user to any anomalous behavior.

  19. Symbolic and graphical representation scheme for sensors deployed in large-scale structures.

    PubMed

    Park, Hyo Seon; Shin, Yunah; Choi, Se Woon; Kim, Yousok

    2013-07-31

    As wireless sensor network (WSN)-based structural health monitoring (SHM) systems are increasingly being employed in civil infrastructures and building structures, the management of large numbers of sensing devices and the large amount of data acquired from WSNs will become increasingly difficult unless systematic expressions of the sensor network are provided. This study introduces a practical WSN for SHM that consists of sensors, wireless sensor nodes, repeater nodes, master nodes, and monitoring servers. This study also proposes a symbolic and graphical representation scheme (SGRS) for this system, in which the communication relationships and respective location information of the distributed sensing components are expressed in a concise manner. The SGRS was applied to the proposed WSN, which is employed in an actual large-scale irregular structure in which three types of sensors (75 vibrating wire strain gauges, 10 inclinometers, and three laser displacement sensors) and customized wireless sensor nodes are installed. The application results demonstrate that prompt identification of sensing units and effective management of the distributed sensor network can be realized from the SGRS. The results also demonstrate the superiority of the SGRS over conventional expression methods in which a box diagram or tree diagram representing the ID of sensors and data loggers is used.

  20. Symbolic and Graphical Representation Scheme for Sensors Deployed in Large-Scale Structures

    PubMed Central

    Park, Hyo Seon; Shin, Yunah; Choi, Se Woon; Kim, Yousok

    2013-01-01

    As wireless sensor network (WSN)-based structural health monitoring (SHM) systems are increasingly being employed in civil infrastructures and building structures, the management of large numbers of sensing devices and the large amount of data acquired from WSNs will become increasingly difficult unless systematic expressions of the sensor network are provided. This study introduces a practical WSN for SHM that consists of sensors, wireless sensor nodes, repeater nodes, master nodes, and monitoring servers. This study also proposes a symbolic and graphical representation scheme (SGRS) for this system, in which the communication relationships and respective location information of the distributed sensing components are expressed in a concise manner. The SGRS was applied to the proposed WSN, which is employed in an actual large-scale irregular structure in which three types of sensors (75 vibrating wire strain gauges, 10 inclinometers, and three laser displacement sensors) and customized wireless sensor nodes are installed. The application results demonstrate that prompt identification of sensing units and effective management of the distributed sensor network can be realized from the SGRS. The results also demonstrate the superiority of the SGRS over conventional expression methods in which a box diagram or tree diagram representing the ID of sensors and data loggers is used. PMID:23912426

  1. Structural vibration control of micro/macro-manipulator using feedforward and feedback approaches

    SciTech Connect

    Lew, J.Y.; Cannon, D.W.; Magee, D.P.; Book, W.J.

    1995-09-01

    Pacific Northwest Laboratory (PDL) researchers investigated the combined use of two control approaches to minimize micro/macro-manipulator structural vibration: (1) modified input shaping and (2) inertial force active damping control. Modified input shaping (MIS) is used as a feedforward controller to modify reference input by canceling the vibratory motion. Inertial force active damping (IFAD) is applied as a feedback controller to increase the system damping and robustness to unexpected disturbances. Researchers implemented both control schemes in the PNL micro/macro flexible-link manipulator testbed collaborating with Georgia Institute of Technology. The experiments successfully demonstrated the effectiveness of two control approaches in reducing structural vibration. Based on the results of the experiments, the combined use of two controllers is recommended for a micro/macro manipulator to achieve the fastest response to commands while canceling disturbances from unexpected forces.

  2. Micro-Structures of Hard Coatings Deposited on Titanium Alloys by Laser Alloying Technique

    NASA Astrophysics Data System (ADS)

    Li, Wei; Yu, Huijun; Chen, Chuanzhong; Wang, Diangang; Weng, Fei

    2013-01-01

    This work is based on micro-structural performance of the Ti-B4C-C laser alloying coatings on Ti-6Al-4V titanium alloy. The test results indicated that laser alloying of the Ti-B4C-C pre-placed powders on the Ti-6Al-4V alloy substrate can form the ceramics reinforced hard alloying coatings, which increased the micro-hardness and wear resistance of substrate. The test result also indicated that the TiB phase was produced in alloying coating, which corresponded to its (101) crystal plane. In addition, yttria has a refining effect on micro-structures of the laser alloying coating, and its refinement mechanism was analyzed. This research provided essential experimental and theoretical basis to promote the applications of the laser alloying technique in manufacturing and repairing of the aerospace parts.

  3. Micro-wrinkling and delamination-induced buckling of stretchable electronic structures

    SciTech Connect

    Oyewole, O. K.; Yu, D.; Du, J.; Asare, J.; Fashina, A.; Oyewole, D. O.; Anye, V. C.; Zebaze Kana, M. G.; and others

    2015-06-21

    This paper presents the results of experimental and theoretical/computational micro-wrinkles and buckling on the surfaces of stretchable poly-dimethylsiloxane (PDMS) coated with nano-scale Gold (Au) layers. The wrinkles and buckles are formed by the unloading of pre-stretched PDMS/Au structure after the evaporation of nano-scale Au layers. They are then characterized using atomic force microscopy and scanning electron microscopy. The critical stresses required for wrinkling and buckling are analyzed using analytical models. The possible interfacial cracking that can occur along with film buckling is also studied using finite element simulations of the interfacial crack growth. The implications of the results are discussed for potential applications of micro-wrinkles and micro-buckles in stretchable electronic structures and biomedical devices.

  4. Wireless structural health monitoring for critical members of civil infrastructures using piezoelectric active sensors

    NASA Astrophysics Data System (ADS)

    Park, Seunghee; Yun, Chung-Bang; Inman, Daniel J.; Park, Gyuhae

    2008-03-01

    This paper presents several challenging issues on wireless structural health monitoring techniques for critical members of civil infrastructures using piezoelectric active sensors. The basic concept of the techniques is to monitor remotely the structural integrity by observing the impedance variations at the piezoelectric active sensors distributed to critical members of a host structure. An active sensing node incorporating on-board microprocessor and radio frequency telemetry is introduced in a sense of tailoring wireless sensing technology to the impedance method. A data compression algorithm using principal component analysis is embedded into the on-board chip of the active sensing node. The data compression algorithm would promote efficiency in terms of both power management and noise elimination of the active sensor node. Finally, a piezoelectric sensor self-diagnosis issue is touched introducing a new impedance model equation that incorporates the effects of sensor and bonding defects.

  5. High-Q Wafer Level Package Based on Modified Tri-Layer Anodic Bonding and High Performance Getter and Its Evaluation for Micro Resonant Pressure Sensor

    PubMed Central

    Wang, Liying; Du, Xiaohui; Wang, Lingyun; Xu, Zhanhao; Zhang, Chenying; Gu, Dandan

    2017-01-01

    In order to achieve and maintain a high quality factor (high-Q) for the micro resonant pressure sensor, this paper presents a new wafer level package by adopting cross-layer anodic bonding technique of the glass/silicon/silica (GSS) stackable structure and integrated Ti getter. A double-layer structure similar to a silicon-on-insulator (SOI) wafer is formed after the resonant layer and the pressure-sensitive layer are bonded by silicon direct bonding (SDB). In order to form good bonding quality between the pressure-sensitive layer and the glass cap layer, the cross-layer anodic bonding technique is proposed for vacuum package by sputtering Aluminum (Al) on the combination wafer of the pressure-sensitive layer and the resonant layer to achieve electrical interconnection. The model and the bonding effect of this technique are discussed. In addition, in order to enhance the performance of titanium (Ti) getter, the prepared and activation parameters of Ti getter under different sputtering conditions are optimized and discussed. Based on the optimized results, the Ti getter (thickness of 300 nm to 500 nm) is also deposited on the inside of the glass groove by magnetron sputtering to maintain stable quality factor (Q). The Q test of the built testing system shows that the number of resonators with a Q value of more than 10,000 accounts for more than 73% of the total. With an interval of 1.5 years, the Q value of the samples remains almost constant. It proves the proposed cross-layer anodic bonding and getter technique can realize high-Q resonant structure for long-term stable operation. PMID:28300752

  6. [Impact of Mikania micrantha invasion on soil meso- and micro-invertebrate community structure].

    PubMed

    Quan, Guo-ming; Zhang, Jia-en; Xie, Jun-fang; Mao, Dan-juan; Xu, Hua-qin; Jiang, Wan-bing; Wen, Du-juan

    2011-07-01

    Mikania micrantha, a notorious exotic weed of Asteraceae family, has invaded successfully in southern China, and caused serious damages to native ecosystems. In this paper, a field survey was conducted in the Huolushan Forest Park of Guangzhou, China, aimed to understand the impact of M. micrantha invasion on the soil meso- and micro-invertebrate community. Three sampling sites were installed, including M. micrantha-invaded site, ecotone, and native vegetation site. Through four samplings in 2009, a total of 5206 soil meso- and micro-invertebrate individuals were collected, belonging to 4 phyla, 10 classes, and 19 orders, among which, Nematoda was the dominant group, and Acarina, Collembolan, and Rotifera were the common groups. M. micrantha invasion altered the characteristics of soil meso- and micro-invertebrate community structure. Compared with those at the other two sampling sites, the numbers of total individuals, Nematoda, and Acarina at M. micrantha-invaded site increased significantly, but the groups of soil meso- and micro-invertebrates had less change. At M. micrantha-invaded site, the density-group index (DG) of soil meso- and micro-invertebrates was significantly higher, Margalef richness index (D) and Simpson dominance index (C) tended to ascend, but Pielou evenness index (E) and Shannon index (H') tended to descend. The similarity coefficient of soil meso- and micro-invertebrate community between M. micrantha-invaded site and ecotone was higher than that between M. micrantha-invaded site and native vegetation site. The changes of local climate conditions, plant litters, root secretions, and soil physical-chemical properties caused by M. micrantha invasion could be the major contributing factors that altered the community structure of soil meso- and micro-invertebrates at M. micrantha-invaded site.

  7. Synthesis, Structure and Properties of BN Nanotubes, BN/SiC and CBN/SiC Micro/Nano-Whiskers

    DTIC Science & Technology

    2003-12-01

    Synthesis, Structure and Properties of BN Nanotubes, BN/SiC and CBN/SiC Micro / Nano -Whiskers 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 5d...Synthesis, Structure and Properties of BN Nanotubes, BN/SiC and CBN/SiC Micro / Nano -Whiskers CRDF COOPERATIVE GRANTS PROGRAM: FINAL PROJECT...SiC and CBN/SiC micro - nano -whiskers. In the result variety of BN nanostructures have been synthesized by carbothermal technique and characterized

  8. Development of multi-functional wireless impedance sensor nodes for structural health monitoring

    NASA Astrophysics Data System (ADS)

    Min, Jiyoung; Park, Seunghee; Yun, Chung-Bang; Song, Byunghun

    2010-04-01

    This study presents the development of a multi-functional wireless sensor node for the impedance-based SHM. The bottom line is to provide multifunctional wireless sensor nodes for low cost and low power excitation/sensing, structural damage detection/sensor self-diagnosis using embedded algorithms, temperature/power monitoring, and energy scavenging. A miniaturized impedance measuring chip is utilized for low cost and low power structural excitation/selfsensing. Then, structural damage detection/sensor self-diagnosis are executed on the on-board microcontroller. Moreover, it can use the harvested power from solar energy to measure and analyze the impedance data. Simultaneously it can monitor temperature and power consumption. In order to validate the feasibility of this multi-functional wireless impedance sensor node, a series of experimental studies have been carried out for detecting loose bolts and crack damages on a lab-scale steel structure as well as on real steel bridge/building structures. As a result, it has been found that the proposed wireless impedance sensor nodes can be effectively used for local health monitoring of structural components and for constructing a low-cost and low-power but multifunctional SHM system as "place and forget" sensors.

  9. Fabrication, Micro-structural Analysis, and Mechanical Testing of High Density Polymeric Foam

    NASA Astrophysics Data System (ADS)

    Marks, Trevor Gustov

    Foams, or what are often called cellular solids, are some of the most widely used materials in the modern era. In general, foam is a porous substance formed by the introduction of gas filled pores into condensed matter; the result is typically a light weight substance with properties related to the base (non-porous) medium. Applications of foams include: vibration dampening, energy mitigation (such as packaging and bike helmets), insulation, filtration, and flotation. The focus of this work is on the properties of flexible elastomeric foam of high relative-density. The bulk of existing literature on elastomeric foam is concerned with foam of low relative-density (ratio of the foam density to the density of the material from which the foam is formed ≤ 0.1). The relationship between the micro-structure of high relative-density foam and its mechanical response has, in large part, not been subjected to systematic investigation heretofore. The present work examines how the micro-structural features of pore shape, size, and location affect the macro-structural response of relative high density foam to compressive loading. In order to carry out this study, methods were developed and employed to control a foam's micro-structure, and hence its mechanical response, with the use of temporary pore forming particles and micron scale inclusions. Advanced microscopy techniques were used to observe, in situ, the evolution of a foam's micro-structure under compressive loading, and the results were correlated with the evolution of the foam's stress - strain response. Additionally, quantitative methods were developed and employed to describe numerically the foam's micro-structural features, such as: (i), pore shape, (ii), pore size, and (iii), the arrangement of the pores with respect to each other. Numerous foams were produced, tested, and subjected to the

  10. Device and nondestructive method to determine subsurface micro-structure in dense materials

    DOEpatents

    Sun, Jiangang

    2006-05-09

    A method and a device to detect subsurface three-dimensional micro-structure in a sample by illuminating the sample with light of a given polarization and detecting light emanating from the sample that has a different direction of polarization by means of a confocal optical system.

  11. [Simulation Study of Dynamic Color Modulation Based on Tunable Micro/Nano-Structure Array].

    PubMed

    Shi, Bin; Zhao, Xiang-dong; Zhu, Nian; Hu, Xiao-lin; Sun, Li-bin; Wang, Xulongqi; Zhang, Dong-xian

    2015-06-01

    With the development of nanotechnology, it has been accessible to display colors by artificial micro/nano-structure, and then the study of structure coloring has become a hot subject, opening a new space for inkless printing. In this paper, a dynamic color modulation method based on tunable micro/nano-structure array is proposed. To tune colors on the same device, a periodic micro/nano-structure array is designed with functional material inside, which could alter the height difference between up and bottom surface precisely by applying an external voltage. It is modeled, and simulated by the Finite Difference Time Domain (FDTD) method in this work. In simulations, perpendicular incident linearly polarized light source is applied, and parameters of surface height difference and period are swept. Series reflective spectra of the devices are obtained, and their corresponding colors are calculated and marked on the CIE 1931 chromaticity diagram. Simulation results demonstrate that when the period is in the range of 100-300 nm, full-color modulation could be realized by varying the height of functional material film via applied voltage, and the peak intensities of reflective spectra are at about 60%, having high energy efficiency. This method is innovative and provides a theoretical basis for the dynamic color modulation micro/nano device, which is quite promising in fields like inkless printing and display technology.

  12. Micro-flow synthesis and structural analysis of sterically crowded diimine ligands with five aryl rings

    PubMed Central

    Tanabe, Nobutake; Tannna, Akio; Konishi, Yohei; Takahashi, Takashi

    2013-01-01

    Summary Sterically crowded diimine ligands with five aryl rings were prepared in one step in good yields using a micro-flow technique. X-ray crystallographic analysis revealed the detailed structure of the bulky ligands. The nickel complexes prepared from the ligands exerted high polymerization activity in the ethylene homopolymerization and copolymerization of ethylene with polar monomers. PMID:24367397

  13. An Alternative to the Problematic Macro-Micro Structure of Introductory Economics.

    ERIC Educational Resources Information Center

    Tinari, Frank D.

    The paper explains an alternative structure to teaching micro and macroeconomic theory and describes the characteristics that make it an effective framework for introductory and principles courses. The teaching of economics principles typically proceeds by separating macroeconomic theory and microeconomic theory. But the use of the macro-micro…

  14. Thick-Film Carbon Dioxide Sensor via Anodic Adsorbate Stripping Technique and Its Structural Dependence.

    PubMed

    Photinon, Kanokorn; Wang, Shih-Han; Liu, Chung-Chiun

    2009-01-01

    A three-electrode based CO(2) sensor was fabricated using thick-film technology. The performance of this sensor was further enhanced by incorporating platinum nanoparticles onto the working electrode surface. An eight-fold increase in the signal output was obtained from the electrode with the platinum nanoparticles. The sensing output was linearly related to the CO(2) presented. Stability measurements demonstrated that the decline of the active surface area and the sensitivity of the sensor were 8% and 13%, respectively, over a two week period of time. The sensor response appeared to be a structural dependence of the crystallographic orientation of platinum electrode.

  15. Fiber-optic intrinsic distributed acoustic emission sensor for large structure health monitoring.

    PubMed

    Liang, Sheng; Zhang, Chunxi; Lin, Wentai; Li, Lijing; Li, Chen; Feng, Xiujuan; Lin, Bo

    2009-06-15

    A fiber-optic intrinsic distributed acoustic emission (AE) sensor is proposed. By measuring the time delay of two signals from two Mach-Zehnder interferometers, the location of AE can be deduced, and the corresponding sensor is experimentally verified to be feasible with a 206 m average location error in a 20 km sensing range, which shows that this proposed sensor is applicable for distributed AE sensing for large structure health monitoring, with the unique advantages of low cost, simple configuration, and long sensing range. The limitations of the proposed sensor are also discussed, and the future work is presented.

  16. Development and Ground-Test Validation of Fiber Optic Sensor Attachment Techniques for Hot Structures Applications

    NASA Technical Reports Server (NTRS)

    Piazza, Anthony; Hudson, Larry D.; Richards, W. Lance

    2005-01-01

    Fiber Optic Strain Measurements: a) Successfully attached silica fiber optic sensors to both metallics and composites; b) Accomplished valid EFPI strain measurements to 1850 F; c) Successfully attached EFPI sensors to large scale hot-structures; and d) Attached and thermally validated FBG bond and epsilon(sub app). Future Development a) Improve characterization of sensors on C-C and C-SiC substrates; b) Apply application to other composites such as SiC-SiC; c) Assist development of interferometer based Sapphire sensor currently being conducted under a Phase II SBIR; and d) Complete combined thermal/mechanical testing of FBG on composite substrates in controlled laboratory environment.

  17. Fabrication and characterization of micro- /nano structures for nanophotonic applications

    NASA Astrophysics Data System (ADS)

    Jee, Hongsub

    The objective of this thesis is finding and developing fabrication methods to provide background techniques for potential applications with nanomaterials. The inclined UV lithography has announced to make three-dimensional fabrication process. With a movable stage, complex structures were achieved but difference of the refractive index, design of the final structures were limited. Refractive index matching medium between the substrate and the light source could reduce the refractive indices between the polymer and the substrate successfully. Nanoporous structures fabricated by multibeam interference lithography shows limitation of the usage since its periodicity. By insertion of the lift off resist layer between the patterned layer and the substrate, final photonic crystal structures could be partially removed for its own purpose and it provide potential application in the future. Two-step processing, combining with reactive ion etching system, nanoporous structures were on various substrates such as silicon and Polydimethylsiloxane. Photonic crystal template anodic aluminum oxide process has been described too. Large optical activity at visible wavelengths are of great attention in photonics. Dramatic enhancement of the optical activity of chiral poly(fluorene-alt-benzothiadiazole) with photoresist was demonstrated and successive photo patterning of chiral polymer shows the potential usage of this material for the photonics applications. Two photon lithography also used to pattern a photoresist-chiral polymer mixture into planar shapes and enhanced chirality can be realized by tuning the wavelength-dependent chiral response at both the molecular and geometric level. Near infrared light induced photopolymerization in-situ was demonstrated which can be applied everywhere where ultraviolet-polymerization is employed such as dentistry, coating industry. Use of the ultraviolet upconverting nanoparticles doped into the polymer, we show that expensive femtosecond pulsed

  18. Structural elements of metal selectivity in metal sensor proteins.

    PubMed

    Pennella, Mario A; Shokes, Jacob E; Cosper, Nathaniel J; Scott, Robert A; Giedroc, David P

    2003-04-01

    Staphylococcus aureus CzrA and Mycobacterium tuberculosis NmtR are homologous zinccobalt-responsive and nickelcobalt-responsive transcriptional repressors in vivo, respectively, and members of the ArsRSmtB superfamily of prokaryotic metal sensor proteins. We show here that Zn(II) is the most potent negative allosteric regulator of czr operatorpromoter binding in vitro with the trend Zn(II)>Co(II)Ni(II), whereas the opposite holds for the binding of NmtR to the nmt operatorpromoter, Ni(II)>Co(II)>Zn(II). Characterization of the metal coordination complexes of CzrA and NmtR by UVvisible and x-ray absorption spectroscopies reveals that metals that form four-coordinate tetrahedral complexes with CzrA [Zn(II) and Co(II)] are potent regulators of DNA binding, whereas metals that form five- or six-coordinate complexes with NmtR [Ni(II) and Co(II)] are the strongest allosteric regulators in this system. Strikingly, the Zn(II) coordination complexes of CzrA and NmtR cannot be distinguished from one another by x-ray absorption spectroscopy, with the best fit a His-3-carboxylate complex in both cases. Inspection of the primary structures of CzrA and NmtR, coupled with previous functional data, suggests that three conserved His and one Asp from the C-terminal alpha5 helix donate ligands to create a four-coordinate complex in both CzrA and NmtR, with NmtR uniquely capable of expanding its coordination number in the Ni(II) and Co(II) complexes by recruiting additional His ligands from a C-terminal extension of the alpha5 helix.

  19. Integrated electrostatic micro-sensors for the development of modeling techniques of defects in the actuation of large micro-electromechanical systems (MEMS)

    NASA Astrophysics Data System (ADS)

    Reissman, Timothy; Garcia, Ephrahim; Lobontiu, Nicolae; Nam, Yoonsu

    2006-03-01

    A micro-electromechanical system (MEMS) was designed by following the saggital principle of motion amplification about an output direction which is pe