TiO2 micro-flowers composed of nanotubes and their application to dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Kim, Woong-Rae; Park, Hun; Choi, Won-Youl

2014-02-01

TiO2 micro-flowers were made to bloom on Ti foil by the anodic oxidation of Ti-protruding dots with a cylindrical shape. Arrays of the Ti-protruding dots were prepared by photolithography, which consisted of coating the photoresists, attaching a patterned mask, illuminating with UV light, etching the Ti surface by reactive ion etching (RIE), and stripping the photoresist on the Ti foil. The procedure for the blooming of the TiO2 micro-flowers was analyzed by field emission scanning electron microscopy (FESEM) as the anodizing time was increased. Photoelectrodes of dye-sensitized solar cells (DSCs) were fabricated using TiO2 micro-flowers. Bare TiO2 nanotube arrays were used for reference samples. The short-circuit current ( J sc) and the power conversion efficiency of the DSCs based on the TiO2 micro-flowers were 4.340 mA/cm2 and 1.517%, respectively. These values of DSCs based on TiO2 micro-flowers were higher than those of bare samples. The TiO2 micro-flowers had a larger surface area for dye adsorption compared to bare TiO2 nanotube arrays, resulting in improved J sc characteristics. The structure of the TiO2 micro-flowers allowed it to adsorb dyes very effectively, also demonstrating the potential to achieve higher power conversion efficiency levels for DSCs compared to a bare TiO2 nanotube array structure and the conventional TiO2 nanoparticle structure.

Uniform Fe3O4 microflowers hierarchical structures assembled with porous nanoplates as superior anode materials for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Wang, Xiaoliang; Liu, Yanguo; Arandiyan, Hamidreza; Yang, Hongping; Bai, Lu; Mujtaba, Jawayria; Wang, Qingguo; Liu, Shanghe; Sun, Hongyu

2016-12-01

Uniform Fe3O4 microflowers assembled with porous nanoplates were successfully synthesized by a solvothermal method and subsequent annealing process. The structural and compositional analysis of the Fe3O4 microflowers were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The Bruauer-Emmett-Teller (BET) specific surface area was calculated by the nitrogen isotherm curve and pore size distribution of Fe3O4 microflowers was determined by the Barret-Joyner-Halenda (BJH) method. When evaluated as anode material for lithium-ion batteries, the as-prepared Fe3O4 microflowers electrodes delivered superior capacity, better cycling stability and rate capability than that of Fe3O4 microspheres electrodes. The improved electrochemical performance was attributed to the microscale flowerlike architecture and the porous sheet structural nature.

Development of polymeric palladium-nanoparticle membrane-installed microflow devices and their application in hydrodehalogenation.

PubMed

Yamada, Yoichi M A; Watanabe, Toshihiro; Ohno, Aya; Uozumi, Yasuhiro

2012-02-13

We have developed a variety of polymeric palladium-nanoparticle membrane-installed microflow devices. Three types of polymers were convoluted with palladium salts under laminar flow conditions in a microflow reactor to form polymeric palladium membranes at the laminar flow interface. These membranes were reduced with aqueous sodium formate or heat to create microflow devices that contain polymeric palladium-nanoparticle membranes. These microflow devices achieved instantaneous hydrodehalogenation of aryl chlorides, bromides, iodides, and triflates by 10-1000 ppm within a residence time of 2-8 s at 50-90 °C by using safe, nonexplosive, aqueous sodium formate to quantitatively afford the corresponding hydrodehalogenated products. Polychlorinated biphenyl (10-1000 ppm) and polybrominated biphenyl (1000 ppm) were completely decomposed under similar conditions, yielding biphenyl as a fungicidal compound. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Experimental evidence of temperature gradients in cavitating microflows seeded with thermosensitive nanoprobes

NASA Astrophysics Data System (ADS)

Ayela, Frédéric; Medrano-Muñoz, Manuel; Amans, David; Dujardin, Christophe; Brichart, Thomas; Martini, Matteo; Tillement, Olivier; Ledoux, Gilles

2013-10-01

Thermosensitive fluorescent nanoparticles seeded in deionized water combined with confocal microscopy enables thermal mapping over three dimensions of the liquid phase flowing through a microchannel interrupted by a microdiaphragm. This experiment reveals the presence of a strong thermal gradient up to ˜105 K/m only when hydrodynamic cavitation is present. Here hydrodynamic cavitation is the consequence of high shear rates downstream in the diaphragm. This temperature gradient is located in vortical structures associated with eddies in the shear layers. We attribute such overheating to the dissipation involved by the cavitating flow regime. Accordingly, we demonstrate that the microsizes of the device enhance the intensity of the thermal gap.

Surface-Cycling of Rhenium and its Isotopes

DTIC Science & Technology

2009-06-01

Fisher Scientific) in the WHOI plasma facility. Samples were introduced using a PFA MicroFlow nebulizer (Elemental Scientific Incorporated), a quartz...Samples were introduced using a PFA MicroFlow nebulizer (Elemental Scientific Incorporated), a quartz spray chamber, and regular cones. Analyses are done in...189Os. Samples dissolved in 1 mL of 0.5 molL−1 HNO3 are introduced using a PFA MicroFlow nebulizer (Elemental Scientific Incorporated), a quartz spray

Parallel multiphase microflows: fundamental physics, stabilization methods and applications.

PubMed

Aota, Arata; Mawatari, Kazuma; Kitamori, Takehiko

2009-09-07

Parallel multiphase microflows, which can integrate unit operations in a microchip under continuous flow conditions, are discussed. Fundamental physics, stabilization methods and some applications are shown.

Conformal chemically resistant coatings for microflow devices

DOEpatents

Folta, James A.; Zdeblick, Mark

2003-05-13

A process for coating the inside surfaces of silicon microflow devices, such as electrophoresis microchannels, with a low-stress, conformal (uniform) silicon nitride film which has the ability to uniformly coat deeply-recessed cavities with, for example, aspect ratios of up to 40:1 or higher. The silicon nitride coating allows extended exposure to caustic solutions. The coating enables a microflow device fabricated in silicon to be resistant to all classes of chemicals: acids, bases, and solvents. The process involves low-pressure (vacuum) chemical vapor deposition. The ultra-low-stress silicon nitride deposition process allows 1-2 .mu.m thick films without cracks, and so enables extended chemical protection of a silicon microflow device against caustics for up to 1 year. Tests have demonstrated the resistance of the films to caustic solutions at both ambient and elevated temperatures to 65.degree. C.

Analysis of skin blood microflow oscillations in patients with rheumatic diseases

NASA Astrophysics Data System (ADS)

Mizeva, Irina; Makovik, Irina; Dunaev, Andrey; Krupatkin, Alexander; Meglinski, Igor

2017-07-01

Laser Doppler flowmetry (LDF) has been applied for the assessment of variation in blood microflows in patients with rheumatic diseases and healthy volunteers. Oscillations of peripheral blood microcirculation observed by LDF have been analyzed utilizing a wavelet transform. A higher amplitude of blood microflow oscillations has been observed in a high frequency band (over 0.1 Hz) in patients with rheumatic diseases. Oscillations in the high frequency band decreased in healthy volunteers in response to the cold pressor test, whereas lower frequency pulsations prevailed in patients with rheumatic diseases. A higher perfusion rate at normal conditions was observed in patients, and a weaker response to cold stimulation was observed in healthy volunteers. Analysis of blood microflow oscillations has a high potential for evaluation of mechanisms of blood flow regulation and diagnosis of vascular abnormalities associated with rheumatic diseases.

Robust, heat-resistant and multifunctional superhydrophobic coating of carbon microflowers with molybdenum trioxide nanoparticles.

PubMed

Wu, Yang; Zhao, Meiyun; Guo, Zhiguang

2017-11-15

Superhydrophobic materials have triggered large interest due to their widespread applications, such as self-cleaning, corrosion resistance, anti-icing, and oil/water separation. However, suffering from weak mechanical strength, plenty of superhydrophobic materials are limited in practical application. Herein, we prepared hierarchical carbon microflowers (CMF) dispersed with molybdenum trioxide (MoO 3 ) nanoparticles (MoO 3 /CMF) via a two-step preparation method. Taking advantage of high-adhesion epoxy resin and the modification with 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PDES), the modified MoO 3 /CMF (PDES-MoO 3 /CMF) coating on various substrates shows great waterproof ability, excellent chemical stability, good mechanical durability, and self-cleaning property. More significantly, the prepared PDES-MoO 3 /CMF powder with high thermal stability (250°C) can be used for oil/water separation due to its special flower-like structure and superhydrophobicity/superoleophilicity. All of these advantages endow the superhydrophobic powders with huge potential in the practical applications. Copyright © 2017 Elsevier Inc. All rights reserved.

Automated Microflow NMR: Routine Analysis of Five-Microliter Samples

PubMed Central

Jansma, Ariane; Chuan, Tiffany; Geierstanger, Bernhard H.; Albrecht, Robert W.; Olson, Dean L.; Peck, Timothy L.

2006-01-01

A microflow CapNMR probe double-tuned for 1H and 13C was installed on a 400-MHz NMR spectrometer and interfaced to an automated liquid handler. Individual samples dissolved in DMSO-d6 are submitted for NMR analysis in vials containing as little as 10 μL of sample. Sets of samples are submitted in a low-volume 384-well plate. Of the 10 μL of sample per well, as with vials, 5 μL is injected into the microflow NMR probe for analysis. For quality control of chemical libraries, 1D NMR spectra are acquired under full automation from 384-well plates on as many as 130 compounds within 24 h using 128 scans per spectrum and a sample-to-sample cycle time of ∼11 min. Because of the low volume requirements and high mass sensitivity of the microflow NMR system, 30 nmol of a typical small molecule is sufficient to obtain high-quality, well-resolved, 1D proton or 2D COSY NMR spectra in ∼6 or 20 min of data acquisition time per experiment, respectively. Implementation of pulse programs with automated solvent peak identification and suppression allow for reliable data collection, even for samples submitted in fully protonated DMSO. The automated microflow NMR system is controlled and monitored using web-based software. PMID:16194121

Porous dimanganese trioxide microflowers derived from microcoordinations for flexible solid-state asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Pang, Huan; Li, Xinran; Li, Bing; Zhang, Yizhou; Zhao, Qunxing; Lai, Wen-Yong; Huang, Wei

2016-06-01

Dimanganese trioxide microflowers are easily obtained from a Mn(ii) 8-hydroxyquinoline microcoordination after calcination in air. We also look into the possible formation mechanism of the flower-like morphology, and find that the reaction time affects the morphology of the coordination. Furthermore, the as-prepared porous Mn2O3 microflowers are made of many nanoplates which form many nanogaps and nanochannels. Interestingly, the assembled electrode based on the as-prepared porous Mn2O3 microflowers proves to be a high-performance electrode material for supercapacitors. The electrode shows a specific capacitance of 994 F g-1, which can work well even after 4000 cycles at 0.75 A g-1. More importantly, the porous Mn2O3 microflowers and activated carbons are assembled into a high-performance flexible solid-state asymmetric supercapacitor with a specific capacitance of 312.5 mF cm-2. The cycle test shows that the device can offer 95.6% capacity of the initial capacitance at 2.0 mA cm-2 after 5000 cycles with little decay. The maximum energy density of the device can achieve 6.56 mWh cm-3 and the maximum power density can also achieve 283.5 mW cm-3, which are among the best results for manganese based materials.Dimanganese trioxide microflowers are easily obtained from a Mn(ii) 8-hydroxyquinoline microcoordination after calcination in air. We also look into the possible formation mechanism of the flower-like morphology, and find that the reaction time affects the morphology of the coordination. Furthermore, the as-prepared porous Mn2O3 microflowers are made of many nanoplates which form many nanogaps and nanochannels. Interestingly, the assembled electrode based on the as-prepared porous Mn2O3 microflowers proves to be a high-performance electrode material for supercapacitors. The electrode shows a specific capacitance of 994 F g-1, which can work well even after 4000 cycles at 0.75 A g-1. More importantly, the porous Mn2O3 microflowers and activated carbons are assembled into a high-performance flexible solid-state asymmetric supercapacitor with a specific capacitance of 312.5 mF cm-2. The cycle test shows that the device can offer 95.6% capacity of the initial capacitance at 2.0 mA cm-2 after 5000 cycles with little decay. The maximum energy density of the device can achieve 6.56 mWh cm-3 and the maximum power density can also achieve 283.5 mW cm-3, which are among the best results for manganese based materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02267g

Long-term, repeated measurements of mouse cortical microflow at the same region of interest with high spatial resolution.

PubMed

Tomita, Yutaka; Pinard, Elisabeth; Tran-Dinh, Alexy; Schiszler, Istvan; Kubis, Nathalie; Tomita, Minoru; Suzuki, Norihiro; Seylaz, Jacques

2011-02-04

A method for long-term, repeated, semi-quantitative measurements of cerebral microflow at the same region of interest (ROI) with high spatial resolution was developed and applied to mice subjected to focal arterial occlusion. A closed cranial window was chronically implanted over the left parieto-occipital cortex. The anesthetized mouse was placed several times, e.g., weekly, under a dynamic confocal microscope, and Rhodamine B-isothiocyanate-dextran was each time intravenously injected as a bolus, while microflow images were video recorded. Left and right tail veins were sequentially catheterized in a mouse three times at maximum over a 1.5 months' observation period. Smearing of the input function resulting from the use of intravenous injection was shown to be sufficiently small. The distal middle cerebral artery (MCA) was thermocoagulated through the cranial window in six mice, and five sham-operated mice were studied in parallel. Dye injection and video recording were conducted four times in this series, i.e., before and at 10 min, 7 and 30 days after sham operation or MCA occlusion. Pixelar microflow values (1/MTT) in a matrix of approximately 50×50 pixels were displayed on a two-dimensional (2-D) map, and the frequency distribution of the flow values was also calculated. No significant changes in microflow values over time were detected in sham-operated mice, while the time course of flow changes in the ischemic penumbral area in operated mice was similar to those reported in the literature. This method provides a powerful tool to investigate long-term changes in mouse cortical microflow under physiological and pathological conditions. Copyright © 2010 Elsevier B.V. All rights reserved.

Nitrogen-doped carbon decorated Cu2NiSnS4 microflowers as superior anode materials for long-life lithium-ion batteries

NASA Astrophysics Data System (ADS)

Pan, Pei; Chen, Lihui; Ding, Yu; Du, Jun; Feng, Chuanqi; Fu, Zhengbin; Qin, Caiqin; Wang, Feng

2018-05-01

Nitrogen-doped carbon (NC) decorated Cu2NiSnS4 (CNTS) microflower composites (NC@CNTS) were fabricated through a facile solvothermal and pyrrole polymerization with further annealing treatment. The NC@CNTS composites possessed a three-dimension (3D) microflower-like hierarchical structure. The unique microflower structure of NC@CNTS composites exhibited remarkable electrochemical performance as electrode materials for long life lithium ion batteries. The as-prepared composites had a stable and reversible capacity that reached 943 mA h g-1 after 160 cycles at a current rate of 0.1 A g-1. It showed satisfactory cycle stability and rate capability even at 2 A g-1, and specific capacity stabilized at 288 mA g-1 after 1000 cycles. The present facile and cost-effective strategy can be applied for the synthesis of other transition metal sulfide nanomaterials for energy storage and conversion applications.

Design and Fabrication of a MEMS Flow Sensor and Its Application in Precise Liquid Dispensing

PubMed Central

Liu, Yaxin; Chen, Liguo; Sun, Lining

2009-01-01

A high speed MEMS flow sensor to enhance the reliability and accuracy of a liquid dispensing system is proposed. Benefitting from the sensor information feedback, the system can self-adjust the open time of the solenoid valve to accurately dispense desired volumes of reagent without any pre-calibration. First, an integrated high-speed liquid flow sensor based on the measurement of the pressure difference across a flow channel is presented. Dimensions of the micro-flow channel and two pressure sensors have been appropriately designed to meet the static and dynamic requirements of the liquid dispensing system. Experiments results show that the full scale (FS) flow measurement ranges up to 80 μL/s, with a nonlinearity better than 0.51% FS. Secondly, a novel closed-loop control strategy is proposed to calculate the valve open time in each dispensing cycle, which makes the system immune to liquid viscosity, pressure fluctuation, and other sources of error. Finally, dispensing results show that the system can achieve better dispensing performance, and the coefficient of variance (CV) for liquid dispensing is below 3% at 1 μL and below 4% at 100 nL. PMID:22408517

Design and Fabrication of a MEMS Flow Sensor and Its Application in Precise Liquid Dispensing.

PubMed

Liu, Yaxin; Chen, Liguo; Sun, Lining

2009-01-01

A high speed MEMS flow sensor to enhance the reliability and accuracy of a liquid dispensing system is proposed. Benefitting from the sensor information feedback, the system can self-adjust the open time of the solenoid valve to accurately dispense desired volumes of reagent without any pre-calibration. First, an integrated high-speed liquid flow sensor based on the measurement of the pressure difference across a flow channel is presented. Dimensions of the micro-flow channel and two pressure sensors have been appropriately designed to meet the static and dynamic requirements of the liquid dispensing system. Experiments results show that the full scale (FS) flow measurement ranges up to 80 μL/s, with a nonlinearity better than 0.51% FS. Secondly, a novel closed-loop control strategy is proposed to calculate the valve open time in each dispensing cycle, which makes the system immune to liquid viscosity, pressure fluctuation, and other sources of error. Finally, dispensing results show that the system can achieve better dispensing performance, and the coefficient of variance (CV) for liquid dispensing is below 3% at 1 μL and below 4% at 100 nL.

Ultrasonic Microtransport

NASA Astrophysics Data System (ADS)

Moroney, Richard Morgan, III

We have observed numerous kinetic effects using ultrasonic flexural plate waves (FPWs) in 4mu -thick composite plates of low-stress silicon nitride, piezoelectric zinc oxide and aluminum. The wavelength is typically 100 mum, and the area 3 x 8 mm^2. A successful new surface micromachining fabrication process is presented here for the first time. FPWs have been used to move liquids and gasses with motion typically indicated by polysilicon blocks in air and polystyrene spheres in water; the velocity in air is 4.5 mm/s (with a zero-to-peak input of 3 V), and in water it is 100 mum/s (with an input of 7.8 V). Other observations include pumping of a liquid dye, and mixing near the FPW surface. All quantitative observations demonstrate that the kinetic effects of FPWs are proportional to the square of the wave amplitude. The amplitude for a typical device is 250 A at 9 V input; the power in a typical FPW is about 2 mW. The amplitude can be accurately measured using a laser diffraction technique. Experimental error is about +/-10%, and many of the results agree well with a simple theory to predict the FPW amplitude; extensions of the theory model the fluid loading of FPW devices, but experiment and theory disagree by about 15%. Pumping by flexural plate waves is an example of the phenomenon known as acoustic streaming. A common solution approach is the method of successive approximations, where the nonlinear equations are first linearized and solved. This "first-order" solution is then used to determine the inhomogeneous source terms in the linearized, "second -order" equations of motion. Theoretical predictions of streaming theory are in excellent agreement with experiment in the case where the FPW device contacts a half-space of fluid; predictions for flow in small channels encourage the development of integrated micropumps. Applications for microflow include thermal redistribution in integrated circuits and liquid movement in analytical instruments--particularly where a small dead volume is required. Capabilities of this technology and further applications are discussed. Microflow systems that integrate transport of fluids and solids with sensing, mixing and other useful tasks may become a new market-leading application for the sensor and actuator field.

Heat Transfer Characteristics of Mixed Electroosmotic and Pressure Driven Micro-Flows

NASA Astrophysics Data System (ADS)

Horiuchi, Keisuke; Dutta, Prashanta

We analyze heat transfer characteristics of steady electroosmotic flows with an arbitrary pressure gradient in two-dimensional straight microchannels considering the effects of Joule heating in electroosmotic pumping. Both the temperature distribution and local Nusselt number are mathematically derived in this study. The thermal analysis takes into consideration of the interaction among advective, diffusive, and Joule heating terms to obtain the thermally developing behavior. Unlike macro-scale pipes, axial conduction in micro-scale cannot be negligible, and the governing energy equation is not separable. Thus, a method that considers an extended Graetz problem is introduced. Analytical results show that the Nusselt number of pure electrooosmotic flow is higher than that of plane Poiseulle flow. Moreover, when the electroosmotic flow and pressure driven flow coexist, it is found that adverse pressure gradient to the electroosmotic flow makes the thermal entrance length smaller and the heat transfer ability stronger than pure electroosmotic flow case.

Utilization of microparticles in next-generation assays for microflow cytometers.

PubMed

Kim, Jason S; Ligler, Frances S

2010-11-01

Micron-sized particles have primarily been used in microfabricated flow cytometers for calibration purposes and proof-of-concept experiments. With increasing frequency, microparticles are serving as a platform for assays measured in these small analytical devices. Light scattering has been used to measure the agglomeration of antibody-coated particles in the presence of an antigen. Impedance detection is another technology being integrated into microflow cytometers for microparticle-based assays. Fluorescence is the most popular detection method in flow cytometry, enabling highly sensitive multiplexed assays. Finally, magnetic particles have also been used to measure antigen levels using a magnetophoretic micro-device. We review the progress of microparticle-based assays in microflow cytometry in terms of the advantages and limitations of each approach.

Rapid trifluoromethylation and perfluoroalkylation of five-membered heterocycles by photoredox catalysis in continuous flow.

PubMed

Straathof, Natan J W; Gemoets, Hannes P L; Wang, Xiao; Schouten, Jaap C; Hessel, Volker; Noël, Timothy

2014-06-01

Trifluoromethylated and perfluoroalkylated heterocycles are important building blocks for the synthesis of numerous pharmaceutical products, agrochemicals and are widely applied in material sciences. To date, trifluoromethylated and perfluoroalkylated hetero-aromatic systems can be prepared utilizing visible light photoredox catalysis methodologies in batch. While several limitations are associated with these batch protocols, the application of microflow technology could greatly enhance and intensify these reactions. A simple and straightforward photocatalytic trifluoromethylation and perfluoroalkylation method has been developed in continuous microflow, using commercially available photocatalysts and microflow components. A selection of five-membered hetero-aromatics were successfully trifluoromethylated (12 examples) and perfluoroalkylated (5 examples) within several minutes (8-20 min). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tear glucose detection combining microfluidic thread based device, amperometric biosensor and microflow injection analysis.

PubMed

Agustini, Deonir; Bergamini, Márcio F; Marcolino-Junior, Luiz Humberto

2017-12-15

The tear glucose analysis is an important alternative for the indirect, simple and less invasive monitoring of blood glucose levels. However, the high cost and complex manufacturing process of tear glucose analyzers combined with the need to exchange the sensor after each analysis in the disposable tests prevent widespread application of the tear in glucose monitoring. Here, we present the integration of a biosensor made by the electropolymerization of poly(toluidine blue O) (PTB) and glucose oxidase (GOx) with an electroanalytical microfluidic device of easy assembly based on cotton threads, low cost materials and measurements by microflow injection analysis (µFIA) through passive pumping for performing tear glucose analyses in a simple, rapid and inexpensive way. A high stability between the analyses (RSD = 2.54%) and among the different systems (RSD = 3.13%) was obtained for the determination of glucose, in addition to a wide linear range between 0.075 and 7.5mmolL -1 and a limit of detection of 22.2µmolL -1 . The proposed method was efficiently employed in the determination of tear glucose in non-diabetic volunteers, obtaining a close correlation with their blood glucose levels, simplifying and reducing the costs of the analyses, making the tear glucose monitoring more accessible for the population. Copyright © 2017 Elsevier B.V. All rights reserved.

Fabrication of Smart Chemical Sensors Based on Transition-Doped-Semiconductor Nanostructure Materials with µ-Chips

PubMed Central

Rahman, Mohammed M.; Khan, Sher Bahadar; Asiri, Abdullah M.

2014-01-01

Transition metal doped semiconductor nanostructure materials (Sb2O3 doped ZnO microflowers, MFs) are deposited onto tiny µ-chip (surface area, ∼0.02217 cm2) to fabricate a smart chemical sensor for toxic ethanol in phosphate buffer solution (0.1 M PBS). The fabricated chemi-sensor is also exhibited higher sensitivity, large-dynamic concentration ranges, long-term stability, and improved electrochemical performances towards ethanol. The calibration plot is linear (r2 = 0.9989) over the large ethanol concentration ranges (0.17 mM to 0.85 M). The sensitivity and detection limit is ∼5.845 µAcm−2mM−1 and ∼0.11±0.02 mM (signal-to-noise ratio, at a SNR of 3) respectively. Here, doped MFs are prepared by a wet-chemical process using reducing agents in alkaline medium, which characterized by UV/vis., FT-IR, Raman, X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), and field-emission scanning electron microscopy (FE-SEM) etc. The fabricated ethanol chemical sensor using Sb2O3-ZnO MFs is simple, reliable, low-sample volume (<70.0 µL), easy of integration, high sensitivity, and excellent stability for the fabrication of efficient I–V sensors on μ-chips. PMID:24454785

Fabrication of smart chemical sensors based on transition-doped-semiconductor nanostructure materials with µ-chips.

PubMed

Rahman, Mohammed M; Khan, Sher Bahadar; Asiri, Abdullah M

2014-01-01

Transition metal doped semiconductor nanostructure materials (Sb2O3 doped ZnO microflowers, MFs) are deposited onto tiny µ-chip (surface area, ∼0.02217 cm(2)) to fabricate a smart chemical sensor for toxic ethanol in phosphate buffer solution (0.1 M PBS). The fabricated chemi-sensor is also exhibited higher sensitivity, large-dynamic concentration ranges, long-term stability, and improved electrochemical performances towards ethanol. The calibration plot is linear (r(2) = 0.9989) over the large ethanol concentration ranges (0.17 mM to 0.85 M). The sensitivity and detection limit is ∼5.845 µAcm(-2)mM(-1) and ∼0.11±0.02 mM (signal-to-noise ratio, at a SNR of 3) respectively. Here, doped MFs are prepared by a wet-chemical process using reducing agents in alkaline medium, which characterized by UV/vis., FT-IR, Raman, X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), and field-emission scanning electron microscopy (FE-SEM) etc. The fabricated ethanol chemical sensor using Sb2O3-ZnO MFs is simple, reliable, low-sample volume (<70.0 µL), easy of integration, high sensitivity, and excellent stability for the fabrication of efficient I-V sensors on μ-chips.

Optofluidic-Tunable Color Filters And Spectroscopy Based On Liquid-Crystal Microflows

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

Cuennet, J. G.; Vasdekis, Andreas E.; Psaltis, D.

The integration of color filters with microfluidics has attracted substantial attention in recent years, for on-chip absorption, fluorescence, or Raman analysis. We describe such tunable filters based on the micro-flow of liquid crystals. The filter operation is based on the wavelength dependent liquid crystal birefringence that can be tuned by modifying the flow velocity field in the microchannel. The latter is possible both temporally and spatially by varying the inlet pressure and the channel geometry respectively. We explored the use of these optofluidic filters for on-chip absorption spectroscopy; by integrating the distance dependent color filter with a dye-filled micro-channel, themore » absorption spectrum of a dye could be measured. Liquid crystal microflows simplify substantially the optofluidic integration, actuation and tuning of color filters for lab-on-a-chip spectroscopic applications.« less

Miniaturized flow injection analysis system

DOEpatents

Folta, James A.

1997-01-01

A chemical analysis technique known as flow injection analysis, wherein small quantities of chemical reagents and sample are intermixed and reacted within a capillary flow system and the reaction products are detected optically, electrochemically, or by other means. A highly miniaturized version of a flow injection analysis system has been fabricated utilizing microfabrication techniques common to the microelectronics industry. The microflow system uses flow capillaries formed by etching microchannels in a silicon or glass wafer followed by bonding to another wafer, commercially available microvalves bonded directly to the microflow channels, and an optical absorption detector cell formed near the capillary outlet, with light being both delivered and collected with fiber optics. The microflow system is designed mainly for analysis of liquids and currently measures 38.times.25.times.3 mm, but can be designed for gas analysis and be substantially smaller in construction.

Trace explosives sensor testbed (TESTbed)

NASA Astrophysics Data System (ADS)

Collins, Greg E.; Malito, Michael P.; Tamanaha, Cy R.; Hammond, Mark H.; Giordano, Braden C.; Lubrano, Adam L.; Field, Christopher R.; Rogers, Duane A.; Jeffries, Russell A.; Colton, Richard J.; Rose-Pehrsson, Susan L.

2017-03-01

A novel vapor delivery testbed, referred to as the Trace Explosives Sensor Testbed, or TESTbed, is demonstrated that is amenable to both high- and low-volatility explosives vapors including nitromethane, nitroglycerine, ethylene glycol dinitrate, triacetone triperoxide, 2,4,6-trinitrotoluene, pentaerythritol tetranitrate, and hexahydro-1,3,5-trinitro-1,3,5-triazine. The TESTbed incorporates a six-port dual-line manifold system allowing for rapid actuation between a dedicated clean air source and a trace explosives vapor source. Explosives and explosives-related vapors can be sourced through a number of means including gas cylinders, permeation tube ovens, dynamic headspace chambers, and a Pneumatically Modulated Liquid Delivery System coupled to a perfluoroalkoxy total-consumption microflow nebulizer. Key features of the TESTbed include continuous and pulseless control of trace vapor concentrations with wide dynamic range of concentration generation, six sampling ports with reproducible vapor profile outputs, limited low-volatility explosives adsorption to the manifold surface, temperature and humidity control of the vapor stream, and a graphical user interface for system operation and testing protocol implementation.

Encapsulation of superparamagnetic Fe 3 O 4 @SiO 2 core/shell nanoparticles in MnO 2 microflowers with high surface areas

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

Sun, Yu-Gang; Truong, Tu T.; Liu, Yu-Zi

2015-02-01

Microflowers made of interconnected MnO2 nanosheets have been successfully synthesized in a microwave reactor through a hydrothermal reduction of KMnO4 with aqueous HCl at elevated temperatures in the presence of superparamagnetic Fe3O4@SiO2 core-shell nanoparticles. Due to the chemical compatibility between SiO2 and MnO2, the heterogeneous reaction leads to the spontaneous encapsulation of the Fe3O4@SiO2 core-shell nanoparticles in the MnO2 microflowers. The resulting hybrid particles exhibit multiple properties including high surface area associated with the MnO2 nanosheets and superparamagnetism originated from the Fe3O4@SiO2 core-shell nanoparticles, which are beneficial for applications requiring both high surface area and magnetic separation. (C) 2014 Yu-Gangmore » Sun.« less

Miniaturized flow injection analysis system

DOEpatents

Folta, J.A.

1997-07-01

A chemical analysis technique known as flow injection analysis is described, wherein small quantities of chemical reagents and sample are intermixed and reacted within a capillary flow system and the reaction products are detected optically, electrochemically, or by other means. A highly miniaturized version of a flow injection analysis system has been fabricated utilizing microfabrication techniques common to the microelectronics industry. The microflow system uses flow capillaries formed by etching microchannels in a silicon or glass wafer followed by bonding to another wafer, commercially available microvalves bonded directly to the microflow channels, and an optical absorption detector cell formed near the capillary outlet, with light being both delivered and collected with fiber optics. The microflow system is designed mainly for analysis of liquids and currently measures 38{times}25{times}3 mm, but can be designed for gas analysis and be substantially smaller in construction. 9 figs.

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

Wang, Yong; State Key Laboratory of Multiphase Complex System, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100080; Zhu, Qingshan, E-mail: qszhu@home.ipe.ac.cn

{beta}-Ni(OH){sub 2} hierarchical micro-flowers, hierarchical hollow microspheres and nanosheets were synthesized via a facile, single-step and selected-control hydrothermal method. Both hierarchical micro-flowers and hierarchical hollow microspheres were built from two-dimensional nanosheets with thickness of 50-100 nm. The as-obtained products were characterized by Brunauer-Emmett-Teller (BET) surface area analysis, X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FESEM). It was observed that marked morphological changes in {beta}-Ni(OH){sub 2} depended on the initial concentrations of Ni{sup 2+} ions and glycine. A possible growth mechanism was proposed based on experimental results. In addition, the effect of morphology on the electrochemical properties wasmore » also investigated. Both hierarchical micro-flowers and hierarchical hollow microspheres exhibited enhanced specific capacity and high-rate discharge ability as compared with pure Ni(OH){sub 2} nanosheets. Investigations confirmed that hierarchical structures had a pronounced influence upon the electrochemical performance of nickel hydroxide.« less

Glucose response of near-infrared alginate-based microsphere sensors under dynamic reversible conditions.

PubMed

Chaudhary, Ayesha; Harma, Harri; Hanninen, Pekka; McShane, Michael J; Srivastava, Rohit

2011-08-01

Minimally invasive optical glucose biosensors with increased functional longevity form one of the most promising techniques for continuous glucose monitoring, because of their long-term stability, reversibility, repeatability, specificity, and high sensitivity. They are based on the principle of competitive binding and fluorescence resonance energy transfer. Moving to the near-infrared region of the spectrum has the potential to improve signal throughput for implanted sensors, but requires a change in dye chemistry that could alter response sensitivity, range, and toxicity profiles. The near-infrared dissolved-core alginate microsphere sensors were fabricated by emulsion followed by surface coating by layer-by-layer self-assembly. The particles were characterized for sensor stability, sensor response, and reversibility in deionized water and simulated interstitial fluid. The sensor response to step changes in bulk glucose concentrations was also evaluated under dynamic conditions using a microflow cell unit. Finally, in vitro cytotoxicity assays were performed with L929 mouse fibroblast cell lines to demonstrate preliminary biocompatibility of the sensors. The glucose sensitivity under controlled and dynamic conditions was observed to be 0.86%/mM glucose with an analytical response range of 0-30 mM glucose, covering both the physiological and pathophysiological range. The sensor demonstrated a repeatable, reversible, and reproducible response, with a maximum response time of 120 s. In vitro cytotoxicity assays revealed nearly 95% viability of cells, thereby suggesting that the alginate microsphere sensor system does not exhibit cytotoxicity. The incorporation of near-infrared dyes shows promise in improving sensor response because of their high sensitivity and improved tissue penetration of infrared light. The sensitivity for the sensors was approximately 1.5 times greater than that observed for visible dye sensors, and the new dye chemistry did not significantly alter the biocompatibility of the materials. These findings provide additional support for the potential application of alginate microspheres and similar systems such as "smart-tattoo" glucose sensors.

Electroosmotic pumps for microflow analysis

PubMed Central

Wang, Xiayan; Wang, Shili; Gendhar, Brina; Cheng, Chang; Byun, Chang Kyu; Li, Guanbin; Zhao, Meiping; Liu, Shaorong

2009-01-01

With rapid development in microflow analysis, electroosmotic pumps are receiving increasing attention. Compared to other micropumps, electroosmotic pumps have several unique features. For example, they are bi-directional, can generate constant and pulse-free flows with flow rates well suited to microanalytical systems, and can be readily integrated with lab-on-chip devices. The magnitude and the direction of flow of an electroosmotic pump can be changed instantly. In addition, electroosmotic pumps have no moving parts. In this article, we discuss common features, introduce fabrication technologies and highlight applications of electroosmotic pumps. PMID:20047021

Micro-flow injection system for the urinary protein assay.

PubMed

Nishihama, Syouhei; Imabayashi, Hisano; Matoba, Tomoko; Toya, Chika; Watanabe, Kosuke; Yoshizuka, Kazuharu

2008-02-15

A urinary protein assay has been investigated, employing a micro-flow injection analysis (muFIA) combined with an adsorptive separation of protein from analyte. The adsorptive separation part of protein in the artificial urine with ceramic hydroxyapatite is integrated on the muFIA chip, since the interference of other components coexisting in urine occurs in the conventional FIA system. The typical FI peak can be obtained following the adsorption-elution process of the protein prior to the detection, and the protein concentration in artificial urine can be quantitatively determined.

Micro-Flow Studies in the 1 to 50 Micron Domain

DTIC Science & Technology

2001-08-01

heating the samples in a torch was sufficient to restore them to their original condition. 18 2.1.1.2 Fabrication of Small (pm) Microchannels UCI was...SUMMARY 1 1.0 INTRODUCTION 1 1.1 Program Overview 1 1.2 Survey of the Literature 3 1.2.1 Flow in Rectangular Microchannel Ducts 3 1.2.2 Heat Transfer...in Microchannel Ducts 6 1.2.3 Other Micro-Flow Studies 8 2.0 STRAIGHT MICROCHANNEL FLOW STUDIES 9 2.1 Experimental Approach 9 2.1.1 Sample Fabrication

Total synthesis of feglymycin based on a linear/convergent hybrid approach using micro-flow amide bond formation

NASA Astrophysics Data System (ADS)

Fuse, Shinichiro; Mifune, Yuto; Nakamura, Hiroyuki; Tanaka, Hiroshi

2016-11-01

Feglymycin is a naturally occurring, anti-HIV and antimicrobial 13-mer peptide that includes highly racemizable 3,5-dihydroxyphenylglycines (Dpgs). Here we describe the total synthesis of feglymycin based on a linear/convergent hybrid approach. Our originally developed micro-flow amide bond formation enabled highly racemizable peptide chain elongation based on a linear approach that was previously considered impossible. Our developed approach will enable the practical preparation of biologically active oligopeptides that contain highly racemizable amino acids, which are attractive drug candidates.

Pumpless Microflow Cytometry Enabled by Viscosity Modulation and Immunobead Labeling.

PubMed

Kim, Byeongyeon; Oh, Sein; Shin, Suyeon; Yim, Sang-Gu; Yang, Seung Yun; Hahn, Young Ki; Choi, Sungyoung

2018-06-19

Major challenges of miniaturizing flow cytometry include obviating the need for bulky, expensive, and complex pump-based fluidic and laser-based optical systems while retaining the ability to detect target cells based on their unique surface receptors. We addressed these critical challenges by (i) using a viscous liquid additive to control flow rate passively, without external pumping equipment, and (ii) adopting an immunobead assay that can be quantified with a portable fluorescence cell counter based on a blue light-emitting diode. Such novel features enable pumpless microflow cytometry (pFC) analysis by simply dropping a sample solution onto the inlet reservoir of a disposable cell-counting chamber. With our pFC platform, we achieved reliable cell counting over a dynamic range of 9-298 cells/μL. We demonstrated the practical utility of the platform by identifying a type of cancer cell based on CD326, the epithelial cell adhesion molecule. This portable microflow cytometry platform can be applied generally to a range of cell types using immunobeads labeled with specific antibodies, thus making it valuable for cell-based and point-of-care diagnostics.

Automated processing integrated with a microflow cytometer for pathogen detection in clinical matrices

PubMed Central

Golden, J.P.; Verbarg, J.; Howell, P.B.; Shriver-Lake, L.C.; Ligler, F.S.

2012-01-01

A spinning magnetic trap (MagTrap) for automated sample processing was integrated with a microflow cytometer capable of simultaneously detecting multiple targets to provide an automated sample-to-answer diagnosis in 40 min. After target capture on fluorescently coded magnetic microspheres, the magnetic trap automatically concentrated the fluorescently coded microspheres, separated the captured target from the sample matrix, and exposed the bound target sequentially to biotinylated tracer molecules and streptavidin-labeled phycoerythrin. The concentrated microspheres were then hydrodynamically focused in a microflow cytometer capable of 4-color analysis (two wavelengths for microsphere identification, one for light scatter to discriminate single microspheres and one for phycoerythrin bound to the target). A three-fold decrease in sample preparation time and an improved detection limit, independent of target preconcentration, was demonstrated for detection of Escherichia coli 0157:H7 using the MagTrap as compared to manual processing. Simultaneous analysis of positive and negative controls, along with the assay reagents specific for the target, was used to obtain dose–response curves, demonstrating the potential for quantification of pathogen load in buffer and serum. PMID:22960010

Automated processing integrated with a microflow cytometer for pathogen detection in clinical matrices.

PubMed

Golden, J P; Verbarg, J; Howell, P B; Shriver-Lake, L C; Ligler, F S

2013-02-15

A spinning magnetic trap (MagTrap) for automated sample processing was integrated with a microflow cytometer capable of simultaneously detecting multiple targets to provide an automated sample-to-answer diagnosis in 40 min. After target capture on fluorescently coded magnetic microspheres, the magnetic trap automatically concentrated the fluorescently coded microspheres, separated the captured target from the sample matrix, and exposed the bound target sequentially to biotinylated tracer molecules and streptavidin-labeled phycoerythrin. The concentrated microspheres were then hydrodynamically focused in a microflow cytometer capable of 4-color analysis (two wavelengths for microsphere identification, one for light scatter to discriminate single microspheres and one for phycoerythrin bound to the target). A three-fold decrease in sample preparation time and an improved detection limit, independent of target preconcentration, was demonstrated for detection of Escherichia coli 0157:H7 using the MagTrap as compared to manual processing. Simultaneous analysis of positive and negative controls, along with the assay reagents specific for the target, was used to obtain dose-response curves, demonstrating the potential for quantification of pathogen load in buffer and serum. Published by Elsevier B.V.

Thermal lattice BGK models for fluid dynamics

NASA Astrophysics Data System (ADS)

Huang, Jian

1998-11-01

As an alternative in modeling fluid dynamics, the Lattice Boltzmann method has attracted considerable attention. In this thesis, we shall present a general form of thermal Lattice BGK. This form can handle large differences in density, temperature, and high Mach number. This generalized method can easily model gases with different adiabatic index values. The numerical transport coefficients of this model are estimated both theoretically and numerically. Their dependency on the sizes of integration steps in time and space, and on the flow velocity and temperature, are studied and compared with other established CFD methods. This study shows that the numerical viscosity of the Lattice Boltzmann method depends linearly on the space interval, and on the flow velocity as well for supersonic flow. This indicates this method's limitation in modeling high Reynolds number compressible thermal flow. On the other hand, the Lattice Boltzmann method shows promise in modeling micro-flows, i.e., gas flows in micron-sized devices. A two-dimensional code has been developed based on the conventional thermal lattice BGK model, with some modifications and extensions for micro- flows and wall-fluid interactions. Pressure-driven micro- channel flow has been simulated. Results are compared with experiments and simulations using other methods, such as a spectral element code using slip boundary condition with Navier-Stokes equations and a Direct Simulation Monte Carlo (DSMC) method.

Investigating Thermal Parameters of PVDF Sensor in the Front Pyroelectric Configuration

NASA Astrophysics Data System (ADS)

Noroozi, Monir; Zakaria, Azmi; Husin, Mohd Shahril; Moksin, Mohd Maarof; Wahab, Zaidan Abd

2013-11-01

A metalized PVDF pyroelectric (PE) sensor was used as an optically opaque sensor and in a thermally thick regime for both sensor and sample, instead of a very thick sensor in the conventional front PE configuration. From the frequency dependence measurements, the normalized amplitude and phase signal were independently analyzed to obtain the thermal effusivity of the sensor. The differential normalized amplitude measured with water as a substrate was analyzed to determine the sensor thermal diffusivity. The PVDF thermal diffusivity and thermal effusivity agree with literature values. Then, from the known thermal parameters of the sensor, the thermal effusivity of a standard liquid sample, glycerol, and other liquids were obtained by the similar procedure.

Towards the minimization of thermodynamic irreversibility in an electrically actuated microflow of a viscoelastic fluid under electrical double layer phenomenon

NASA Astrophysics Data System (ADS)

Sarma, Rajkumar; Jain, Manish; Mondal, Pranab Kumar

2017-10-01

We discuss the entropy generation minimization for electro-osmotic flow of a viscoelastic fluid through a parallel plate microchannel under the combined influences of interfacial slip and conjugate transport of heat. We use in this study the simplified Phan-Thien-Tanner model to describe the rheological behavior of the viscoelastic fluid. Using Navier's slip law and thermal boundary conditions of the third kind, we solve the transport equations analytically and evaluate the global entropy generation rate of the system. We examine the influential role of the following parameters on the entropy generation rate of the system, viz., the viscoelastic parameter (ɛDe2), Debye-Hückel parameter ( κ ¯ ) , channel wall thickness (δ), thermal conductivity of the wall (γ), Biot number (Bi), Peclet number (Pe), and axial temperature gradient (B). This investigation finally establishes the optimum values of the abovementioned parameters, leading to the minimum entropy generation of the system. We believe that results of this analysis could be helpful in optimizing the second-law performance of microscale thermal management devices, including the micro-heat exchangers, micro-reactors, and micro-heat pipes.

Effect of polyethylene glycol conjugation on conformational and colloidal stability of a monoclonal antibody antigen-binding fragment (Fab').

PubMed

Roque, Cristopher; Sheung, Anthony; Rahman, Nausheen; Ausar, S Fernando

2015-02-02

We have investigated the effects of site specific "hinge" polyethylene glycol conjugation (PEGylation) on thermal, pH, and colloidal stability of a monoclonal antibody antigen-binding fragment (Fab') using a variety of biophysical techniques. The results obtained by circular dichroism (CD), ultraviolet (UV) absorbance, and fluorescence spectroscopy suggested that the physical stability of the Fab' is maximized at pH 6-7 with no apparent differences due to PEGylation. Temperature-induced aggregation experiments revealed that PEGylation was able to increase the transition temperature, as well as prevent the formation of visible and subvisible aggregates. Statistical comparison of the three-index empirical phase diagram (EPD) revealed significant differences in thermal and pH stability signatures between Fab' and PEG-Fab'. Upon mechanical stress, micro-flow imaging (MFI) and measurement of the optical density at 360 nm showed that the PEG-Fab' had significantly higher resistance to surface-induced aggregation compared to the Fab'. Analysis of the interaction parameter, kD, indicated repulsive intermolecular forces for PEG-Fab' and attractive forces for Fab'. In conclusion, PEGylation appears to protect Fab' against thermal and mechanical stress-induced aggregation, likely due to a steric hindrance mechanism.

Hydrodynamic focusing investigation in a micro-flow cytometer.

PubMed

Yang, An-Shik; Hsieh, Wen-Hsin

2007-04-01

Hydrodynamic focusing behavior is characterized by two fluids coflowing at different velocities inside a micro-flow cytometer. In this study, a two-fluid model has been established to describe the flow transport behavior and interaction of sample and sheath fluids. The analysis treats the sample and sheath fluids as two-dimensional, laminar, incompressible, and isothermal. The theoretical model comprises two groups of transient conservation equations of mass and momentum with consideration of the interfacial momentum exchange. The governing equations are solved numerically through an iterative SIMPLEC algorithm to determine the flow properties. Since the ratio of the sheath velocity to the sample velocity varies from 5 to 70, the predicted focusing width and length are in good agreement with the experimental data in the literature. In addition, the present study explored the hydrodynamic focusing flowfield as well as the pressure drop across a micro-flow cytometer and the time needed for the completion of one focusing event in detail. To enhance the understanding of hydrodynamic focusing in the design of cytometers, ten numerical experiments were conducted to examine the effects of the inner nozzle length, inner nozzle exit width, inner nozzle shape, and fluid properties on the width of the focused sample stream.

Combined use of laser Doppler flowmetry and skin thermometry for functional diagnostics of intradermal finger vessels.

PubMed

Zherebtsov, Evgeny A; Zherebtsova, Angelina I; Doronin, Alexander; Dunaev, Andrey V; Podmasteryev, Konstantin V; Bykov, Alexander; Meglinski, Igor

2017-04-01

We introduce a noninvasive diagnostic approach for functional monitoring of blood microflows in capillaries and thermoregulatory vessels within the skin. The measuring system is based on the combined use of laser Doppler flowmetry and skin contact thermometry. The obtained results suggest that monitoring of blood microcirculation during the occlusion, performed in conjunction with the skin temperature measurements in the thermally stabilized medium, has a great potential for quantitative assessment of angiospatic dysfunctions of the peripheral blood vessels. The indices of blood flow reserve and temperature response were measured and used as the primarily parameters of the functional diagnostics of the peripheral vessels of skin. Utilizing these parameters, a simple phenomenological model has been suggested to identify patients with angiospastic violations in the vascular system.

Combined use of laser Doppler flowmetry and skin thermometry for functional diagnostics of intradermal finger vessels

NASA Astrophysics Data System (ADS)

Zherebtsov, Evgeny A.; Zherebtsova, Angelina I.; Doronin, Alexander; Dunaev, Andrey V.; Podmasteryev, Konstantin V.; Bykov, Alexander; Meglinski, Igor

2017-04-01

We introduce a noninvasive diagnostic approach for functional monitoring of blood microflows in capillaries and thermoregulatory vessels within the skin. The measuring system is based on the combined use of laser Doppler flowmetry and skin contact thermometry. The obtained results suggest that monitoring of blood microcirculation during the occlusion, performed in conjunction with the skin temperature measurements in the thermally stabilized medium, has a great potential for quantitative assessment of angiospatic dysfunctions of the peripheral blood vessels. The indices of blood flow reserve and temperature response were measured and used as the primarily parameters of the functional diagnostics of the peripheral vessels of skin. Utilizing these parameters, a simple phenomenological model has been suggested to identify patients with angiospastic violations in the vascular system.

Biomonitoring of Organophosphorus Agent Exposure by Reactivation of Cholinesterase Enzyme Based on Carbon Nanotube-Enhanced Flow-Injection Amperometric Detection

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

Du, Dan; Wang, Jun; Smith, Jordan N.

2009-11-15

A portable, rapid, and sensitive assessment of sub-clinical organophosphorus (OPs) agent exposure based on reactivation of cholinesterase (ChE) from OP-inhibited ChE using rat saliva (in vitro) was developed using an electrochemical sensor coupled with a microflow-injection system. The sensor was based on a carbon nanotube (CNT)-modified screen printed carbon electrode (SPE), which was integrated into a flow cell. Due to the extent of inter-individual ChE activity variability, ChE biomonitoring often requires an initial base-line determination (non-inhibited) of enzyme activity which is then directly compared with activity after OP exposure. This manuscript described an alternative strategy where reactivation of the phosphorylatedmore » enzyme was exploited to enable measurement of both inhibited and baseline ChE activity (i.e. after reactivation) in the same sample. The use of CNT makes the electrochemical detection of the products from enzymatic reactions more feasible with extremely high sensitivity and at low potentials. Paraoxon was selected as a model OP compound for in vitro inhibition studies. Some experiment parameters, (e.g. inhibition and reactivation times), have been optimized such that, 92 - 95% ChE reactivation can be achieved over a broad range of ChE inhibition (5 - 94 %) with paraoxon. The extent of enzyme inhibition using this electrochemical sensor correlates well with conventional enzyme activity measurements.« less

Ag nanoparticle-functionalized ZnO micro-flowers for enhanced photodegradation of herbicide derivatives

NASA Astrophysics Data System (ADS)

Xu, Yan; Wu, Shumin; Li, Xianliang; Meng, Hao; Zhang, Xia; Wang, Zhuopeng; Han, Yide

2017-07-01

We demonstrate a general strategy to design step by step the Ag nanoparticle-functionalized ZnO micro-flowers (Ag/ZnO composites). XRD patterns confirmed the presence of Ag nanoparticles in ZnO/Ag composites, and the SEM and TEM results further demonstrated that Ag nanoparticles were highly dispersed and anchored onto the surface of each ZnO nanosheets. By using the ZnO/Ag composites, the photodegradation of two herbicide derivatives, metamitron and metribuzin, were studied. The enhanced photocatalytic performance was ascribed to the fact that the Ag deposition could reduce the recombination probability of electron-hole pairs, and the photocatalytic mechanism were also investigated in this paper.

Characterization of Propylene Glycol-Mitigated Freeze/Thaw Agglomeration of a Frozen Liquid nOMV Vaccine Formulation by Static Light Scattering and Micro-Flow Imaging.

PubMed

Mensch, Christopher D; Davis, Harrison B; Blue, Jeffrey T

2015-01-01

The purpose of this work was to investigate the susceptibility of an aluminum adjuvant and an aluminum-adjuvanted native outer membrane vesicle (nOMV) vaccine formulation to freeze/thaw-induced agglomeration using static light scattering and micro-flow Imaging analysis; and to evaluate the use of propylene glycol as a vaccine formulation excipient by which freeze/thaw-induced agglomeration of a nOMV vaccine formulation could be mitigated. Our results indicate that including 7% v/v propylene glycol in an nOMV containing aluminum adjuvanted vaccine formulation, mitigates freeze/thaw-induced agglomeration. We evaluated the effect of freeze-thawing on an aluminum adjuvant and an aluminum adjuvanted native outer membrane vesicle (nOMV) vaccine formulation. Specifically, we characterized the freeze/thaw-induced agglomeration through the use of static light scattering, micro-flow imaging, and cryo-electron microscopy analysis. Further, we evaluated the use of 0-9% v/v propylene glycol as an excipient which could be included in the formulation for the purpose of mitigating the agglomeration induced by freeze/thaw. The results indicate that using 7% v/v propylene glycol as a formulation excipient is effective at mitigating agglomeration of the nOMV vaccine formulation, otherwise induced by freeze-thawing. © PDA, Inc. 2015.

Thermal Flow Sensors for Harsh Environments.

PubMed

Balakrishnan, Vivekananthan; Phan, Hoang-Phuong; Dinh, Toan; Dao, Dzung Viet; Nguyen, Nam-Trung

2017-09-08

Flow sensing in hostile environments is of increasing interest for applications in the automotive, aerospace, and chemical and resource industries. There are thermal and non-thermal approaches for high-temperature flow measurement. Compared to their non-thermal counterparts, thermal flow sensors have recently attracted a great deal of interest due to the ease of fabrication, lack of moving parts and higher sensitivity. In recent years, various thermal flow sensors have been developed to operate at temperatures above 500 °C. Microelectronic technologies such as silicon-on-insulator (SOI), and complementary metal-oxide semiconductor (CMOS) have been used to make thermal flow sensors. Thermal sensors with various heating and sensing materials such as metals, semiconductors, polymers and ceramics can be selected according to the targeted working temperature. The performance of these thermal flow sensors is evaluated based on parameters such as thermal response time, flow sensitivity. The data from thermal flow sensors reviewed in this paper indicate that the sensing principle is suitable for the operation under harsh environments. Finally, the paper discusses the packaging of the sensor, which is the most important aspect of any high-temperature sensing application. Other than the conventional wire-bonding, various novel packaging techniques have been developed for high-temperature application.

Thermal Flow Sensors for Harsh Environments

PubMed Central

Dinh, Toan; Dao, Dzung Viet

2017-01-01

Flow sensing in hostile environments is of increasing interest for applications in the automotive, aerospace, and chemical and resource industries. There are thermal and non-thermal approaches for high-temperature flow measurement. Compared to their non-thermal counterparts, thermal flow sensors have recently attracted a great deal of interest due to the ease of fabrication, lack of moving parts and higher sensitivity. In recent years, various thermal flow sensors have been developed to operate at temperatures above 500 °C. Microelectronic technologies such as silicon-on-insulator (SOI), and complementary metal-oxide semiconductor (CMOS) have been used to make thermal flow sensors. Thermal sensors with various heating and sensing materials such as metals, semiconductors, polymers and ceramics can be selected according to the targeted working temperature. The performance of these thermal flow sensors is evaluated based on parameters such as thermal response time, flow sensitivity. The data from thermal flow sensors reviewed in this paper indicate that the sensing principle is suitable for the operation under harsh environments. Finally, the paper discusses the packaging of the sensor, which is the most important aspect of any high-temperature sensing application. Other than the conventional wire-bonding, various novel packaging techniques have been developed for high-temperature application. PMID:28885595

Controllable synthesis of Ln3+ (Ln = Tb, Eu) doped zinc phosphate nano-/micro-structured materials: phase, morphology and luminescence properties

NASA Astrophysics Data System (ADS)

Yue, Dan; Lu, Wei; Li, Chunyang; Zhang, Xinlei; Liu, Chunxia; Wang, Zhenling

2014-01-01

Ln3+ (Ln = Tb, Eu) doped zinc phosphate tetrahydrate (ZPT:Ln3+) and ammonium zinc phosphate (AZP:Ln3+) nano-/micro-structured materials were synthesized in aqueous solution without the addition of any structure-directing agent. The phase structures, morphologies and luminescence properties of the as-synthesized samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy and lifetime. These investigations indicate that different phosphate sources MnH(3-n)PO4 (M = NH4+ or Na+, n = 1, 2, 3) can lead to the altering of morphology from nanosheet to microflower, but have no significant effect on the phase structure of the samples. The microlump, nanosheet, and microflower (constructed by the primary microlumps or nanosheets) of orthorhombic ZPT:Ln3+ could be selectively prepared by adjusting the pH value from 3.5 to 7.0. A mixture of orthorhombic ZPT:Ln3+ and monoclinic AZP:Ln3+ with a microflower morphology was obtained when the pH value was adjusted to 8.0. Monoclinic AZP:Ln3+ microplate, microcube and nanoparticle morphologies were obtained at pH values of 8.5, 9.0 and 11.0 respectively. The phase transformation and growth mechanism of the diverse morphologies were proposed, and ZPT:Ln3+ (Ln3+ = Eu or Tb) samples exhibit red or green emission under the excitation of UV light.Ln3+ (Ln = Tb, Eu) doped zinc phosphate tetrahydrate (ZPT:Ln3+) and ammonium zinc phosphate (AZP:Ln3+) nano-/micro-structured materials were synthesized in aqueous solution without the addition of any structure-directing agent. The phase structures, morphologies and luminescence properties of the as-synthesized samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy and lifetime. These investigations indicate that different phosphate sources MnH(3-n)PO4 (M = NH4+ or Na+, n = 1, 2, 3) can lead to the altering of morphology from nanosheet to microflower, but have no significant effect on the phase structure of the samples. The microlump, nanosheet, and microflower (constructed by the primary microlumps or nanosheets) of orthorhombic ZPT:Ln3+ could be selectively prepared by adjusting the pH value from 3.5 to 7.0. A mixture of orthorhombic ZPT:Ln3+ and monoclinic AZP:Ln3+ with a microflower morphology was obtained when the pH value was adjusted to 8.0. Monoclinic AZP:Ln3+ microplate, microcube and nanoparticle morphologies were obtained at pH values of 8.5, 9.0 and 11.0 respectively. The phase transformation and growth mechanism of the diverse morphologies were proposed, and ZPT:Ln3+ (Ln3+ = Eu or Tb) samples exhibit red or green emission under the excitation of UV light. Electronic supplementary information (ESI) available: Additional XRD patterns, EDX, SEM and TEM images, dependence of the average lifetimes on the different doping concentrations of Eu3+ and Tb3+. See DOI: 10.1039/c3nr03749e

Solar Probe Plus MAG Sensor Thermal Design for Low Heater Power and Extreme Thermal Environment

NASA Technical Reports Server (NTRS)

Choi, Michael K.

2015-01-01

The heater power available for the Solar Probe Plus FIELDS MAG sensor is less than half of the heritage value for other missions. Nominally the MAG sensors are in the spacecraft's umbra. In the worst hot case, approximately 200 spacecraft communication downlinks, up to 10 hours each, are required at 0.7 AU. These downlinks require the spacecraft to slew 45 deg. about the Y-axis, exposing the MAG sensors and boom to sunlight. This paper presents the thermal design to meet the MAG sensor thermal requirements in the extreme thermal environment and with low heater power. A thermal balance test on the MAG sensor engineering model has verified the thermal design and correlated the thermal model for flight temperature predictions.

Landsat and Thermal Infrared Imaging

NASA Technical Reports Server (NTRS)

Arvidson, Terry; Barsi, Julia; Jhabvala, Murzy; Reuter, Dennis

2012-01-01

The purpose of this chapter is to describe the collection of thermal images by Landsat sensors already on orbit and to introduce the new thermal sensor to be launched in 2013. The chapter describes the thematic mapper (TM) and enhanced thematic mapper plus (ETM+) sensors, the calibration of their thermal bands, and the design and prelaunch calibration of the new thermal infrared sensor (TIRS).

A new boundary scheme for simulation of gas flow in kerogen pores with considering surface diffusion effect

NASA Astrophysics Data System (ADS)

Wang, Lingquan; Zeng, Zhong; Zhang, Liangqi; Qiao, Long; Zhang, Yi; Lu, Yiyu

2018-04-01

Navier-Stokes (NS) equations with no-slip boundary conditions fail to realistically describe micro-flows with considering nanoscale phenomena. Particularly, in kerogen pores, slip-flow and surface diffusion are important. In this study, we propose a new slip boundary scheme for the lattice Boltzmann (LB) method through the non-equilibrium extrapolation scheme to simulate the slip-flow considering surface diffusion effect. Meanwhile, the second-order slip velocity can be taken into account. The predicted characteristics in a two-dimensional micro-flow, including slip-velocity, velocity distribution along the flow direction with/without surface diffusion are present. The results in this study are compared with available analytical and reference results, and good agreements are achieved.

Chemical preconcentrator with integral thermal flow sensor

DOEpatents

Manginell, Ronald P.; Frye-Mason, Gregory C.

2003-01-01

A chemical preconcentrator with integral thermal flow sensor can be used to accurately measure fluid flow rate in a microanalytical system. The thermal flow sensor can be operated in either constant temperature or constant power mode and variants thereof. The chemical preconcentrator with integral thermal flow sensor can be fabricated with the same MEMS technology as the rest of the microanlaytical system. Because of its low heat capacity, low-loss, and small size, the chemical preconcentrator with integral thermal flow sensor is fast and efficient enough to be used in battery-powered, portable microanalytical systems.

NiO-Microflower Formed by Nanowire-weaving Nanosheets with Interconnected Ni-network Decoration as Supercapacitor Electrode

PubMed Central

Ci, Suqing; Wen, Zhenhai; Qian, Yuanyuan; Mao, Shun; Cui, Shumao; Chen, Junhong

2015-01-01

We propose a ‘weaving’ evolution mechanism, by systematically investigating the products obtained in controlled experiments, to demonstrate the formation of Ni-based ‘microflowers’ which consists of multiple characteristic dimensions, in which the three dimensional (3D) NiO ‘microflower’ is constructed by a two-dimensional (2D) nanosheet framework that is derived from weaving one-dimensional (1D) nanowires. We found such unique nanostructures are conducive for the generation of an electrically conductive Ni-network on the nanosheet surface after being exposed to a reducing atmosphere. Our study offers a promising strategy to address the intrinsic issue of poor electrical conductivity for NiO-based materials with significant enhancement of utilization of NiO active materials, leading to a remarkable improvement in the performance of the Ni-NiO microflower based supercapacitor. The optimized Ni-NiO microflower material showed a mass specific capacitance of 1,828 F g−1, and an energy density of 15.9 Wh kg−1 at a current density of 0.5 A g−1. This research not only contributes to understanding the formation mechanism of such ‘microflower’ structures but also offers a promising route to advance NiO based supercapacitor given their ease of synthesis, low cost, and long-term stability. PMID:26165386

Active Flow Separation Control of a Stator Vane Using Surface Injection in a Multistage Compressor Experiment

NASA Technical Reports Server (NTRS)

Culley, Dennis E.; Bright, Michelle M.; Prahst, Patricia S.; Strazisar, Anthony J.

2003-01-01

Micro-flow control actuation embedded in a stator vane was used to successfully control separation and improve near stall performance in a multistage compressor rig at NASA Glenn. Using specially designed stator vanes configured with internal actuation to deliver pulsating air through slots along the suction surface, a research study was performed to identify performance benefits using this microflow control approach. Pressure profiles and unsteady pressure measurements along the blade surface and at the shroud provided a dynamic look at the compressor during microflow air injection. These pressure measurements lead to a tracking algorithm to identify the onset of separation. The testing included steady air injection at various slot locations along the vane. The research also examined the benefit of pulsed injection and actively controlled air injection along the stator vane. Two types of actuation schemes were studied, including an embedded actuator for on-blade control. Successful application of an online detection and flow control scheme will be discussed. Testing showed dramatic performance benefit for flow reattachment and subsequent improvement in diffusion through the use of pulsed controlled injection. The paper will discuss the experimental setup, the blade configurations, and preliminary CFD results which guided the slot location along the blade. The paper will also show the pressure profiles and unsteady pressure measurements used to track flow control enhancement, and will conclude with the tracking algorithm for adjusting the control.

Indium sulfide microflowers: Fabrication and optical properties

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

Zhu Hui; Wang Xiaolei; Yang Wen

2009-10-15

With the assistance of urea, uniform 2D nanoflakes assembled 3D In{sub 2}S{sub 3} microflowers were synthesized via a facile hydrothermal method at relative low temperature. The properties of the as-obtained In{sub 2}S{sub 3} flowers were characterized by various techniques. In this work, the utilization of urea and L-cysteine, as well as the amount of them played important roles in the formation of In{sub 2}S{sub 3} with different nanostructures. Inferred from their morphology evolution, a urea induced precursor-decomposition associated with the Ostwald-ripening mechanism was proposed to interpret these hierarchical structure formation. Furthermore, the optical properties of these In{sub 2}S{sub 3} microflowersmore » were investigated via UV-vis absorption and photoluminescence (PL) spectroscopies in detail.« less

Improved Livingness and Control over Branching in RAFT Polymerization of Acrylates: Could Microflow Synthesis Make the Difference?

PubMed

Derboven, Pieter; Van Steenberge, Paul H M; Vandenbergh, Joke; Reyniers, Marie-Francoise; Junkers, Thomas; D'hooge, Dagmar R; Marin, Guy B

2015-12-01

The superior capabilities of structured microreactors over batch reactors are demonstrated for reversible addition-fragmentation chain transfer (RAFT) solution polymerization of n-butyl acrylate with the aid of simulations, explicitly accounting for the chain length distribution of all macrospecies types. Since perfect isothermicity can be established in a microreactor, less side products due to backbiting and β-scission are formed compared to the batch operation in which ineffective heat removal leads to an undesirable temperature spike. For a given RAFT chain transfer agent (CTA), additional microstructural control results under microflow conditions by optimizing the reaction temperature, lowering the dilution degree, or decreasing the initial molar ratio of monomer to RAFT CTA. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transient plane source (tps) sensors for simultaneous measurements of thermal conductivity and thermal diffusivity of insulators, fluids and conductors

NASA Astrophysics Data System (ADS)

Maqsood, Asghari; Anis-ur-Rehman, M.

2013-12-01

Thermal conductivity and thermal diffusivity are two important physical properties for designing any food engineering processes1. The knowledge of thermal properties of the elements, compounds and different materials in many industrial applications is a requirement for their final functionality. Transient plane source (tps) sensors are reported2 to be useful for the simultaneous measurement of thermal conductivity, thermal diffusivity and volumetric heat capacity of insulators, conductor liquids3 and high-TC superconductors4. The tps-sensor consists of a resistive element in the shape of double spiral made of 10 micrometer thick Ni-foils covered on both sides with 25 micrometer thick Kapton. This sensor acts both as a heat source and a resistance thermometer for recording the time dependent temperature increase. From the knowledge of the temperature co-efficient of the metal spiral, the temperature increase of the sensor can be determined precisely by placing the sensor in between two surfaces of the same material under test. This temperature increase is then related to the thermal conductivity, thermal diffusivity and volumetric heat capacity by simple relations2,5. The tps-sensor has been used to measure thermal conductivities from 0.001 Wm-1K-1to 600 Wm-1K-1 and temperature ranges covered from 77K- 1000K. This talk gives the design, advantages and limitations of the tpl-sensor along with its applications to the measurementof thermal properties in a variety of materials.

Dynamic Response Analysis of Microflow Electrochemical Sensors with Two Types of Elastic Membrane

PubMed Central

Zhou, Qiuzhan; Wang, Chunhui; Chen, Yongzhi; Chen, Shuozhang; Lin, Jun

2016-01-01

The Molecular Electric Transducer (MET), widely applied for vibration measurement, has excellent sensitivity and dynamic response at low frequencies. The elastic membrane in the MET is a significant factor with an obvious effect on the performance of the MET in the low frequency domain and is the focus of this paper. In simulation experiments, the elastic membrane and the reaction cavity of the MET were analysed in a model based on the multiphysics finite element method. Meanwhile, the effects caused by the elastic membrane elements are verified in this paper. With the numerical simulation and practical experiments, a suitable elastic membrane can be designed for different cavity structures. Thus, the MET can exhibit the best dynamic response characteristics to measure the vibration signals. With the new method presented in this paper, it is possible to develop and optimize the characteristics of the MET effectively, and the dynamic characteristics of the MET can be improved in a thorough and systematic manner. PMID:27171086

The microflow behavior and interphase characterization of fiber-reinforced polymer composites

NASA Astrophysics Data System (ADS)

Foley, Maureen Elizabeth

There is typically a trade off that takes place when designing a composite part for ballistic purposes. Structural strength requirements typically call for less than 1% voids with strong adhesion between the fiber and matrix whereas for ballistic applications, such as spall plates for body armor where energy absorbing properties are paramount, the composites are usually resin lean and have weaker fiber matrix interphases. The energy absorbing properties of a composite can be tailored through the sizings applied to the fiber or through control of the resin infiltration of the composite part. The goal of this research was two pronged. The first was to develop a transverse microflow model that could be used to predict the microflow within a tow assuming it is completely surrounded by resin. The models developed consider the capillary pressure on the flow front, which is typically ignored by literature models, as the main driving force for transverse flow into the fiber bundles. This capillary pressure is a function of the surface properties of the resin and fiber and by tailoring these properties one can control the microflow of the resin. The dynamic model, which takes into account the fiber radius, fiber volume fraction, fiber count, resin contact angle with the fiber and the resin surface tension, was used to study the effects of tow count, fiber volume fraction and contact angle on the infiltration time. The second goal of this research was the development of an interphase characterization methodology that can be used to evaluate the interphase properties, using the Dynamic Interphase Loading Apparatus (DILA), once the fiber preforms are infiltrated. The DILA is a unique piece of equipment that allows one to pushout a fiber from a thin composite slice while recording the resulting force and displacement. The interphase characterization process includes indenter selection, sample and test configuration design, test parameters, post test validation and data reduction. This process was used to evaluate glass fiber reinforced epoxy and vinyl ester systems under quasi-static and cyclic loading as examples of the DILA capabilities.

Thermal sensors to control polymer forming. Challenge and solutions

NASA Astrophysics Data System (ADS)

Lemeunier, F.; Boyard, N.; Sarda, A.; Plot, C.; Lefèvre, N.; Petit, I.; Colomines, G.; Allanic, N.; Bailleul, J. L.

2017-10-01

Many thermal sensors are already used, for many years, to better understand and control material forming processes, especially polymer processing. Due to technical constraints (high pressure, sealing, sensor dimensions…) the thermal measurement is often performed in the tool or close its surface. Thus, it only gives partial and disturbed information. Having reliable information about the heat flux exchanges between the tool and the material during the process would be very helpful to improve the control of the process and to favor the development of new materials. In this work, we present several sensors developed in labs to study the molding steps in forming processes. The analysis of the obtained thermal measurements (temperature, heat flux) shows the required sensitivity threshold of sensitivity of thermal sensors to be able to detect on-line the rate of thermal reaction. Based on these data, we will present new sensor designs which have been patented.

Nature-Inspired Design of Artificial Solar-to-Fuel Conversion Systems based on Copper Phosphate Microflowers.

PubMed

Wang, Jing; Zhu, Ting; Ho, Ghim Wei

2016-07-07

Phosphates play significant roles in plant photosynthesis by mediating electron transportation and furnishing energy for CO2 reduction. Motivated by this, we demonstrate herein an artificial solar-to-fuel conversion system, involving versatile copper phosphate microflowers as template and titanium dioxide nanoparticles as host photocatalyst. The elaborate flowerlike architectures, coupled with a unique proton-reduction cycle from interchangeability of different species of orthophosphate ions, not only offer a 2D nanosheet platform for an optimal heterostructure interface but also effectively augment charge-carrier transfer, thereby contributing to enhanced photoactivity and hydrogen generation. These nature-inspired, phosphate-derived nanocomposites advance the synthesis of a large variety of functional materials, which holds great potential for photochemical, photoelectric and catalytic applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controllable synthesis of Ln3+ (Ln = Tb, Eu) doped zinc phosphate nano-/micro-structured materials: phase, morphology and luminescence properties.

PubMed

Yue, Dan; Lu, Wei; Li, Chunyang; Zhang, Xinlei; Liu, Chunxia; Wang, Zhenling

2014-02-21

Ln(3+) (Ln = Tb, Eu) doped zinc phosphate tetrahydrate (ZPT:Ln(3+)) and ammonium zinc phosphate (AZP:Ln(3+)) nano-/micro-structured materials were synthesized in aqueous solution without the addition of any structure-directing agent. The phase structures, morphologies and luminescence properties of the as-synthesized samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy and lifetime. These investigations indicate that different phosphate sources MnH(3-n)PO4 (M = NH4(+) or Na(+), n = 1, 2, 3) can lead to the altering of morphology from nanosheet to microflower, but have no significant effect on the phase structure of the samples. The microlump, nanosheet, and microflower (constructed by the primary microlumps or nanosheets) of orthorhombic ZPT:Ln(3+) could be selectively prepared by adjusting the pH value from 3.5 to 7.0. A mixture of orthorhombic ZPT:Ln(3+) and monoclinic AZP:Ln(3+) with a microflower morphology was obtained when the pH value was adjusted to 8.0. Monoclinic AZP:Ln(3+) microplate, microcube and nanoparticle morphologies were obtained at pH values of 8.5, 9.0 and 11.0 respectively. The phase transformation and growth mechanism of the diverse morphologies were proposed, and ZPT:Ln(3+) (Ln(3+) = Eu or Tb) samples exhibit red or green emission under the excitation of UV light.

Hydrothermal Microflow Technology as a Research Tool for Origin-of-Life Studies in Extreme Earth Environments

PubMed Central

Kawamura, Kunio

2017-01-01

Although studies about the origin of life are a frontier in science and a number of effective approaches have been developed, drawbacks still exist. Examples include: (1) simulation of chemical evolution experiments (which were demonstrated for the first time by Stanley Miller); (2) approaches tracing back the most primitive life-like systems (on the basis of investigations of present organisms); and (3) constructive approaches for making life-like systems (on the basis of molecular biology), such as in vitro construction of the RNA world. Naturally, simulation experiments of chemical evolution under plausible ancient Earth environments have been recognized as a potentially fruitful approach. Nevertheless, simulation experiments seem not to be sufficient for identifying the scenario from molecules to life. This is because primitive Earth environments are still not clearly defined and a number of possibilities should be taken into account. In addition, such environments frequently comprise extreme conditions when compared to the environments of present organisms. Therefore, we need to realize the importance of accurate and convenient experimental approaches that use practical research tools, which are resistant to high temperature and pressure, to facilitate chemical evolution studies. This review summarizes improvements made in such experimental approaches over the last two decades, focusing primarily on our hydrothermal microflow reactor technology. Microflow reactor systems are a powerful tool for performing simulation experiments in diverse simulated hydrothermal Earth conditions in order to measure the kinetics of formation and degradation and the interactions of biopolymers. PMID:28974048

On-Line Temperature Estimation for Noisy Thermal Sensors Using a Smoothing Filter-Based Kalman Predictor

PubMed Central

Li, Zhi; Wei, Henglu; Zhou, Wei; Duan, Zhemin

2018-01-01

Dynamic thermal management (DTM) mechanisms utilize embedded thermal sensors to collect fine-grained temperature information for monitoring the real-time thermal behavior of multi-core processors. However, embedded thermal sensors are very susceptible to a variety of sources of noise, including environmental uncertainty and process variation. This causes the discrepancies between actual temperatures and those observed by on-chip thermal sensors, which seriously affect the efficiency of DTM. In this paper, a smoothing filter-based Kalman prediction technique is proposed to accurately estimate the temperatures from noisy sensor readings. For the multi-sensor estimation scenario, the spatial correlations among different sensor locations are exploited. On this basis, a multi-sensor synergistic calibration algorithm (known as MSSCA) is proposed to improve the simultaneous prediction accuracy of multiple sensors. Moreover, an infrared imaging-based temperature measurement technique is also proposed to capture the thermal traces of an advanced micro devices (AMD) quad-core processor in real time. The acquired real temperature data are used to evaluate our prediction performance. Simulation shows that the proposed synergistic calibration scheme can reduce the root-mean-square error (RMSE) by 1.2 ∘C and increase the signal-to-noise ratio (SNR) by 15.8 dB (with a very small average runtime overhead) compared with assuming the thermal sensor readings to be ideal. Additionally, the average false alarm rate (FAR) of the corrected sensor temperature readings can be reduced by 28.6%. These results clearly demonstrate that if our approach is used to perform temperature estimation, the response mechanisms of DTM can be triggered to adjust the voltages, frequencies, and cooling fan speeds at more appropriate times. PMID:29393862

On-Line Temperature Estimation for Noisy Thermal Sensors Using a Smoothing Filter-Based Kalman Predictor.

PubMed

Li, Xin; Ou, Xingtao; Li, Zhi; Wei, Henglu; Zhou, Wei; Duan, Zhemin

2018-02-02

Dynamic thermal management (DTM) mechanisms utilize embedded thermal sensors to collect fine-grained temperature information for monitoring the real-time thermal behavior of multi-core processors. However, embedded thermal sensors are very susceptible to a variety of sources of noise, including environmental uncertainty and process variation. This causes the discrepancies between actual temperatures and those observed by on-chip thermal sensors, which seriously affect the efficiency of DTM. In this paper, a smoothing filter-based Kalman prediction technique is proposed to accurately estimate the temperatures from noisy sensor readings. For the multi-sensor estimation scenario, the spatial correlations among different sensor locations are exploited. On this basis, a multi-sensor synergistic calibration algorithm (known as MSSCA) is proposed to improve the simultaneous prediction accuracy of multiple sensors. Moreover, an infrared imaging-based temperature measurement technique is also proposed to capture the thermal traces of an advanced micro devices (AMD) quad-core processor in real time. The acquired real temperature data are used to evaluate our prediction performance. Simulation shows that the proposed synergistic calibration scheme can reduce the root-mean-square error (RMSE) by 1.2 ∘ C and increase the signal-to-noise ratio (SNR) by 15.8 dB (with a very small average runtime overhead) compared with assuming the thermal sensor readings to be ideal. Additionally, the average false alarm rate (FAR) of the corrected sensor temperature readings can be reduced by 28.6%. These results clearly demonstrate that if our approach is used to perform temperature estimation, the response mechanisms of DTM can be triggered to adjust the voltages, frequencies, and cooling fan speeds at more appropriate times.

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

PubMed Central

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

2010-01-01

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

Dancing the tight rope on the nanoscale—Calibrating a heat flux sensor of a scanning thermal microscope

NASA Astrophysics Data System (ADS)

Kloppstech, K.; Könne, N.; Worbes, L.; Hellmann, D.; Kittel, A.

2015-11-01

We report on a precise in situ procedure to calibrate the heat flux sensor of a near-field scanning thermal microscope. This sensitive thermal measurement is based on 1ω modulation technique and utilizes a hot wire method to build an accessible and controllable heat reservoir. This reservoir is coupled thermally by near-field interactions to our probe. Thus, the sensor's conversion relation V th ( QGS ∗ ) can be precisely determined. Vth is the thermopower generated in the sensor's coaxial thermocouple and QGS ∗ is the thermal flux from reservoir through the sensor. We analyze our method with Gaussian error calculus with an error estimate on all involved quantities. The overall relative uncertainty of the calibration procedure is evaluated to be about 8% for the measured conversion constant, i.e., (2.40 ± 0.19) μV/μW. Furthermore, we determine the sensor's thermal resistance to be about 0.21 K/μW and find the thermal resistance of the near-field mediated coupling at a distance between calibration standard and sensor of about 250 pm to be 53 K/μW.

Tracking and Classification of In-Air Hand Gesture Based on Thermal Guided Joint Filter.

PubMed

Kim, Seongwan; Ban, Yuseok; Lee, Sangyoun

2017-01-17

The research on hand gestures has attracted many image processing-related studies, as it intuitively conveys the intention of a human as it pertains to motional meaning. Various sensors have been used to exploit the advantages of different modalities for the extraction of important information conveyed by the hand gesture of a user. Although many works have focused on learning the benefits of thermal information from thermal cameras, most have focused on face recognition or human body detection, rather than hand gesture recognition. Additionally, the majority of the works that take advantage of multiple modalities (e.g., the combination of a thermal sensor and a visual sensor), usually adopting simple fusion approaches between the two modalities. As both thermal sensors and visual sensors have their own shortcomings and strengths, we propose a novel joint filter-based hand gesture recognition method to simultaneously exploit the strengths and compensate the shortcomings of each. Our study is motivated by the investigation of the mutual supplementation between thermal and visual information in low feature level for the consistent representation of a hand in the presence of varying lighting conditions. Accordingly, our proposed method leverages the thermal sensor's stability against luminance and the visual sensors textural detail, while complementing the low resolution and halo effect of thermal sensors and the weakness against illumination of visual sensors. A conventional region tracking method and a deep convolutional neural network have been leveraged to track the trajectory of a hand gesture and to recognize the hand gesture, respectively. Our experimental results show stability in recognizing a hand gesture against varying lighting conditions based on the contribution of the joint kernels of spatial adjacency and thermal range similarity.

Wearable Sweat Rate Sensors for Human Thermal Comfort Monitoring.

PubMed

Sim, Jai Kyoung; Yoon, Sunghyun; Cho, Young-Ho

2018-01-19

We propose watch-type sweat rate sensors capable of automatic natural ventilation by integrating miniaturized thermo-pneumatic actuators, and experimentally verify their performances and applicability. Previous sensors using natural ventilation require manual ventilation process or high-power bulky thermo-pneumatic actuators to lift sweat rate detection chambers above skin for continuous measurement. The proposed watch-type sweat rate sensors reduce operation power by minimizing expansion fluid volume to 0.4 ml through heat circuit modeling. The proposed sensors reduce operation power to 12.8% and weight to 47.6% compared to previous portable sensors, operating for 4 hours at 6 V batteries. Human experiment for thermal comfort monitoring is performed by using the proposed sensors having sensitivity of 0.039 (pF/s)/(g/m 2 h) and linearity of 97.9% in human sweat rate range. Average sweat rate difference for each thermal status measured in three subjects shows (32.06 ± 27.19) g/m 2 h in thermal statuses including 'comfortable', 'slightly warm', 'warm', and 'hot'. The proposed sensors thereby can discriminate and compare four stages of thermal status. Sweat rate measurement error of the proposed sensors is less than 10% under air velocity of 1.5 m/s corresponding to human walking speed. The proposed sensors are applicable for wearable and portable use, having potentials for daily thermal comfort monitoring applications.

Enhancing thermal reliability of fiber-optic sensors for bio-inspired applications at ultra-high temperatures

NASA Astrophysics Data System (ADS)

Kang, Donghoon; Kim, Heon-Young; Kim, Dae-Hyun

2014-07-01

The rapid growth of bio-(inspired) sensors has led to an improvement in modern healthcare and human-robot systems in recent years. Higher levels of reliability and better flexibility, essential features of these sensors, are very much required in many application fields (e.g. applications at ultra-high temperatures). Fiber-optic sensors, and fiber Bragg grating (FBG) sensors in particular, are being widely studied as suitable sensors for improved structural health monitoring (SHM) due to their many merits. To enhance the thermal reliability of FBG sensors, thermal sensitivity, generally expressed as αf + ξf and considered a constant, should be investigated more precisely. For this purpose, the governing equation of FBG sensors is modified using differential derivatives between the wavelength shift and the temperature change in this study. Through a thermal test ranging from RT to 900 °C, the thermal sensitivity of FBG sensors is successfully examined and this guarantees thermal reliability of FBG sensors at ultra-high temperatures. In detail, αf + ξf has a non-linear dependence on temperature and varies from 6.0 × 10-6 °C-1 (20 °C) to 10.6 × 10-6 °C-1 (650 °C). Also, FBGs should be carefully used for applications at ultra-high temperatures due to signal disappearance near 900 °C.

The analysis and rationale behind the upgrading of existing standard definition thermal imagers to high definition

NASA Astrophysics Data System (ADS)

Goss, Tristan M.

2016-05-01

With 640x512 pixel format IR detector arrays having been on the market for the past decade, Standard Definition (SD) thermal imaging sensors have been developed and deployed across the world. Now with 1280x1024 pixel format IR detector arrays becoming readily available designers of thermal imager systems face new challenges as pixel sizes reduce and the demand and applications for High Definition (HD) thermal imaging sensors increases. In many instances the upgrading of existing under-sampled SD thermal imaging sensors into more optimally sampled or oversampled HD thermal imaging sensors provides a more cost effective and reduced time to market option than to design and develop a completely new sensor. This paper presents the analysis and rationale behind the selection of the best suited HD pixel format MWIR detector for the upgrade of an existing SD thermal imaging sensor to a higher performing HD thermal imaging sensor. Several commercially available and "soon to be" commercially available HD small pixel IR detector options are included as part of the analysis and are considered for this upgrade. The impact the proposed detectors have on the sensor's overall sensitivity, noise and resolution is analyzed, and the improved range performance is predicted. Furthermore with reduced dark currents due to the smaller pixel sizes, the candidate HD MWIR detectors are operated at higher temperatures when compared to their SD predecessors. Therefore, as an additional constraint and as a design goal, the feasibility of achieving upgraded performance without any increase in the size, weight and power consumption of the thermal imager is discussed herein.

The effect of winding and core support material on the thermal gain dependence of a fluxgate magnetometer sensor

NASA Astrophysics Data System (ADS)

Miles, David M.; Mann, Ian R.; Kale, Andy; Milling, David K.; Narod, Barry B.; Bennest, John R.; Barona, David; Unsworth, Martyn J.

2017-10-01

Fluxgate magnetometers are an important tool in geophysics and space physics but are typically sensitive to variations in sensor temperature. Changes in instrumental gain with temperature, thermal gain dependence, are thought to be predominantly due to changes in the geometry of the wire coils that sense the magnetic field and/or provide magnetic feedback. Scientific fluxgate magnetometers typically employ some form of temperature compensation and support and constrain wire sense coils with bobbins constructed from materials such as MACOR machinable ceramic (Corning Inc.) which are selected for their ultra-low thermal deformation rather than for robustness, cost, or ease of manufacturing. We present laboratory results comparing the performance of six geometrically and electrically matched fluxgate sensors in which the material used to support the windings and for the base of the sensor is varied. We use a novel, low-cost thermal calibration procedure based on a controlled sinusoidal magnetic source and quantitative spectral analysis to measure the thermal gain dependence of fluxgate magnetometer sensors at the ppm°C-1 level in a typical magnetically noisy university laboratory environment. We compare the thermal gain dependence of sensors built from MACOR, polyetheretherketone (PEEK) engineering plastic (virgin, 30 % glass filled and 30 % carbon filled), and acetal to examine the trade between the thermal properties of the material, the impact on the thermal gain dependence of the fluxgate, and the cost and ease of manufacture. We find that thermal gain dependence of the sensor varies as one half of the material properties of the bobbin supporting the wire sense coils rather than being directly related as has been historically thought. An experimental sensor constructed from 30 % glass-filled PEEK (21.6 ppm°C-1) had a thermal gain dependence within 5 ppm°C-1 of a traditional sensor constructed from MACOR ceramic (8.1 ppm°C-1). If a modest increase in thermal dependence can be tolerated or compensated, then 30 % glass-filled PEEK is a good candidate for future fluxgate sensors as it is more economical, easier to machine, lighter, and more robust than MACOR.

Automated DBS microsampling, microscale automation and microflow LC-MS for therapeutic protein PK.

PubMed

Zhang, Qian; Tomazela, Daniela; Vasicek, Lisa A; Spellman, Daniel S; Beaumont, Maribel; Shyong, BaoJen; Kenny, Jacqueline; Fauty, Scott; Fillgrove, Kerry; Harrelson, Jane; Bateman, Kevin P

2016-04-01

Reduce animal usage for discovery-stage PK studies for biologics programs using microsampling-based approaches and microscale LC-MS. We report the development of an automated DBS-based serial microsampling approach for studying the PK of therapeutic proteins in mice. Automated sample preparation and microflow LC-MS were used to enable assay miniaturization and improve overall assay throughput. Serial sampling of mice was possible over the full 21-day study period with the first six time points over 24 h being collected using automated DBS sample collection. Overall, this approach demonstrated comparable data to a previous study using single mice per time point liquid samples while reducing animal and compound requirements by 14-fold. Reduction in animals and drug material is enabled by the use of automated serial DBS microsampling for mice studies in discovery-stage studies of protein therapeutics.

Template-Free Solvothermal Synthesis of Flower-Like BiOBr Microspheres in Ethanol Medium for Photocatalytic Applications

NASA Astrophysics Data System (ADS)

Hong, Shaoming; Ren, Huijun; Fang, Yanfeng; Huang, Yingping; Li, Ruiping

2018-05-01

Three-dimensionally (3D) BiOBr microflowers were prepared by a simple solvothermal method, employing Bi(NO3)3 · 5H2O and NaBr as starting reagents in ethanol. The structural, light absorption and morphological properties of as-prepared BiOBr microspheres were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis diffuse reflectance spectroscopy (DRS), etc. The results showed that ethanol acted not only as a solvent but also as a template in 3D BiOBr preparation. The BiOBr microspheres exhibited superior photocatalytic activity compared with 2D BiOBr nanosheets, far exceeding that of TiO2 (Degussa, P25). It was found that both superoxide radical (O2 •-) and holes (h+) played a key role in the degradation of RhB by BiOBr microflowers.

Advanced Wireless Sensor Nodes - MSFC

NASA Technical Reports Server (NTRS)

Varnavas, Kosta; Richeson, Jeff

2017-01-01

NASA field center Marshall Space Flight Center (Huntsville, AL), has invested in advanced wireless sensor technology development. Developments for a wireless microcontroller back-end were primarily focused on the commercial Synapse Wireless family of devices. These devices have many useful features for NASA applications, good characteristics and the ability to be programmed Over-The-Air (OTA). The effort has focused on two widely used sensor types, mechanical strain gauges and thermal sensors. Mechanical strain gauges are used extensively in NASA structural testing and even on vehicle instrumentation systems. Additionally, thermal monitoring with many types of sensors is extensively used. These thermal sensors include thermocouples of all types, resistive temperature devices (RTDs), diodes and other thermal sensor types. The wireless thermal board will accommodate all of these types of sensor inputs to an analog front end. The analog front end on each of the sensors interfaces to the Synapse wireless microcontroller, based on the Atmel Atmega128 device. Once the analog sensor output data is digitized by the onboard analog to digital converter (A/D), the data is available for analysis, computation or transmission. Various hardware features allow custom embedded software to manage battery power to enhance battery life. This technology development fits nicely into using numerous additional sensor front ends, including some of the low-cost printed circuit board capacitive moisture content sensors currently being developed at Auburn University.

Application of High-Temperature Extrinsic Fabry-Perot Interferometer Strain Sensor

NASA Technical Reports Server (NTRS)

Piazza, Anthony

2008-01-01

In this presentation to the NASA Aeronautics Sensor Working Group the application of a strain sensor is outlined. The high-temperature extrinsic Fabry-Perot interferometer (EFPI) strain sensor was developed due to a need for robust strain sensors that operate accurately and reliably beyond 1800 F. Specifically, the new strain sensor would provide data for validating finite element models and thermal-structural analyses. Sensor attachment techniques were also developed to improve methods of handling and protecting the fragile sensors during the harsh installation process. It was determined that thermal sprayed attachments are preferable even though cements are simpler to apply as cements are more prone to bond failure and are often corrosive. Previous thermal/mechanical cantilever beam testing of EFPI yielded very little change to 1200 F, with excellent correlation with SG to 550 F. Current combined thermal/mechanical loading for sensitivity testing is accomplished by a furnace/cantilever beam loading system. Dilatometer testing has can also be used in sensor characterization to evaluate bond integrity, evaluate sensitivity and accuracy and to evaluate sensor-to-sensor scatter, repeatability, hysteresis and drift. Future fiber optic testing will examine single-mode silica EFPIs in a combined thermal/mechanical load fixture on C-C and C-SiC substrates, develop a multi-mode Sapphire strain-sensor, test and evaluate high-temperature fiber Bragg Gratings for use as strain and temperature sensors and attach and evaluate a high-temperature heat flux gauge.

Tracking and Classification of In-Air Hand Gesture Based on Thermal Guided Joint Filter

PubMed Central

Kim, Seongwan; Ban, Yuseok; Lee, Sangyoun

2017-01-01

The research on hand gestures has attracted many image processing-related studies, as it intuitively conveys the intention of a human as it pertains to motional meaning. Various sensors have been used to exploit the advantages of different modalities for the extraction of important information conveyed by the hand gesture of a user. Although many works have focused on learning the benefits of thermal information from thermal cameras, most have focused on face recognition or human body detection, rather than hand gesture recognition. Additionally, the majority of the works that take advantage of multiple modalities (e.g., the combination of a thermal sensor and a visual sensor), usually adopting simple fusion approaches between the two modalities. As both thermal sensors and visual sensors have their own shortcomings and strengths, we propose a novel joint filter-based hand gesture recognition method to simultaneously exploit the strengths and compensate the shortcomings of each. Our study is motivated by the investigation of the mutual supplementation between thermal and visual information in low feature level for the consistent representation of a hand in the presence of varying lighting conditions. Accordingly, our proposed method leverages the thermal sensor’s stability against luminance and the visual sensors textural detail, while complementing the low resolution and halo effect of thermal sensors and the weakness against illumination of visual sensors. A conventional region tracking method and a deep convolutional neural network have been leveraged to track the trajectory of a hand gesture and to recognize the hand gesture, respectively. Our experimental results show stability in recognizing a hand gesture against varying lighting conditions based on the contribution of the joint kernels of spatial adjacency and thermal range similarity. PMID:28106716

IMAPS Device Packaging Conference 2017 - Engineered Micro Systems & Devices Track

NASA Technical Reports Server (NTRS)

Varnavas, Kosta

2017-01-01

NASA field center Marshall Space Flight Center (Huntsville, AL), has invested in advanced wireless sensor technology development. Developments for a wireless microcontroller back-end were primarily focused on the commercial Synapse Wireless family of devices. These devices have many useful features for NASA applications, good characteristics and the ability to be programmed Over-The-Air (OTA). The effort has focused on two widely used sensor types, mechanical strain gauges and thermal sensors. Mechanical strain gauges are used extensively in NASA structural testing and even on vehicle instrumentation systems. Additionally, thermal monitoring with many types of sensors is extensively used. These thermal sensors include thermocouples of all types, resistive temperature devices (RTDs), diodes and other thermal sensor types. The wireless thermal board will accommodate all of these types of sensor inputs to an analog front end. The analog front end on each of the sensors interfaces to the Synapse wireless microcontroller, based on the Atmel Atmega128 device. Once the analog sensor output data is digitized by the onboard analog to digital converter (A/D), the data is available for analysis, computation or transmission. Various hardware features allow custom embedded software to manage battery power to enhance battery life. This technology development fits nicely into using numerous additional sensor front ends, including some of the low-cost printed circuit board capacitive moisture content sensors currently being developed at Auburn University.

Microhotplate Temperature Sensor Calibration and BIST.

PubMed

Afridi, M; Montgomery, C; Cooper-Balis, E; Semancik, S; Kreider, K G; Geist, J

2011-01-01

In this paper we describe a novel long-term microhotplate temperature sensor calibration technique suitable for Built-In Self Test (BIST). The microhotplate thermal resistance (thermal efficiency) and the thermal voltage from an integrated platinum-rhodium thermocouple were calibrated against a freshly calibrated four-wire polysilicon microhotplate-heater temperature sensor (heater) that is not stable over long periods of time when exposed to higher temperatures. To stress the microhotplate, its temperature was raised to around 400 °C and held there for days. The heater was then recalibrated as a temperature sensor, and microhotplate temperature measurements were made based on the fresh calibration of the heater, the first calibration of the heater, the microhotplate thermal resistance, and the thermocouple voltage. This procedure was repeated 10 times over a period of 80 days. The results show that the heater calibration drifted substantially during the period of the test while the microhotplate thermal resistance and the thermocouple-voltage remained stable to within about plus or minus 1 °C over the same period. Therefore, the combination of a microhotplate heater-temperature sensor and either the microhotplate thermal resistance or an integrated thin film platinum-rhodium thermocouple can be used to provide a stable, calibrated, microhotplate-temperature sensor, and the combination of the three sensor is suitable for implementing BIST functionality. Alternatively, if a stable microhotplate-heater temperature sensor is available, such as a properly annealed platinum heater-temperature sensor, then the thermal resistance of the microhotplate and the electrical resistance of the platinum heater will be sufficient to implement BIST. It is also shown that aluminum- and polysilicon-based temperature sensors, which are not stable enough for measuring high microhotplate temperatures (>220 °C) without impractically frequent recalibration, can be used to measure the silicon substrate temperature if never exposed to temperatures above about 220 °C.

Cryogenic fiber optic temperature sensor and method of manufacturing the same

NASA Technical Reports Server (NTRS)

Kochergin, Vladimir (Inventor)

2012-01-01

This invention teaches the fiber optic sensors temperature sensors for cryogenic temperature range with improved sensitivity and resolution, and method of making said sensors. In more detail, the present invention is related to enhancement of temperature sensitivity of fiber optic temperature sensors at cryogenic temperatures by utilizing nanomaterials with a thermal expansion coefficient that is smaller than the thermal expansion coefficient of the optical fiber but larger in absolute value than the thermal expansion coefficient of the optical fiber at least over a range of temperatures.

High accuracy thermal conductivity measurement of aqueous cryoprotective agents and semi-rigid biological tissues using a microfabricated thermal sensor

PubMed Central

Liang, Xin M.; Sekar, Praveen K.; Zhao, Gang; Zhou, Xiaoming; Shu, Zhiquan; Huang, Zhongping; Ding, Weiping; Zhang, Qingchuan; Gao, Dayong

2015-01-01

An improved thermal-needle approach for accurate and fast measurement of thermal conductivity of aqueous and soft biomaterials was developed using microfabricated thermal conductivity sensors. This microscopic measuring device was comprehensively characterized at temperatures from 0 °C to 40 °C. Despite the previous belief, system calibration constant was observed to be highly temperature-dependent. Dynamic thermal conductivity response during cooling (40 °C to –40 °C) was observed using the miniaturized single tip sensor for various concentrations of CPAs, i.e., glycerol, ethylene glycol and dimethyl sulfoxide. Chicken breast, chicken skin, porcine limb, and bovine liver were assayed to investigate the effect of anatomical heterogeneity on thermal conductivity using the arrayed multi-tip sensor at 20 °C. Experimental results revealed distinctive differences in localized thermal conductivity, which suggests the use of approximated or constant property values is expected to bring about results with largely inflated uncertainties when investigating bio-heat transfer mechanisms and/or performing sophisticated thermal modeling with complex biological tissues. Overall, the presented micro thermal sensor with automated data analysis algorithm is a promising approach for direct thermal conductivity measurement of aqueous solutions and soft biomaterials and is of great value to cryopreservation of tissues, hyperthermia or cryogenic, and other thermal-based clinical diagnostics and treatments. PMID:25993037

High accuracy thermal conductivity measurement of aqueous cryoprotective agents and semi-rigid biological tissues using a microfabricated thermal sensor

NASA Astrophysics Data System (ADS)

Liang, Xin M.; Sekar, Praveen K.; Zhao, Gang; Zhou, Xiaoming; Shu, Zhiquan; Huang, Zhongping; Ding, Weiping; Zhang, Qingchuan; Gao, Dayong

2015-05-01

An improved thermal-needle approach for accurate and fast measurement of thermal conductivity of aqueous and soft biomaterials was developed using microfabricated thermal conductivity sensors. This microscopic measuring device was comprehensively characterized at temperatures from 0 °C to 40 °C. Despite the previous belief, system calibration constant was observed to be highly temperature-dependent. Dynamic thermal conductivity response during cooling (40 °C to -40 °C) was observed using the miniaturized single tip sensor for various concentrations of CPAs, i.e., glycerol, ethylene glycol and dimethyl sulfoxide. Chicken breast, chicken skin, porcine limb, and bovine liver were assayed to investigate the effect of anatomical heterogeneity on thermal conductivity using the arrayed multi-tip sensor at 20 °C. Experimental results revealed distinctive differences in localized thermal conductivity, which suggests the use of approximated or constant property values is expected to bring about results with largely inflated uncertainties when investigating bio-heat transfer mechanisms and/or performing sophisticated thermal modeling with complex biological tissues. Overall, the presented micro thermal sensor with automated data analysis algorithm is a promising approach for direct thermal conductivity measurement of aqueous solutions and soft biomaterials and is of great value to cryopreservation of tissues, hyperthermia or cryogenic, and other thermal-based clinical diagnostics and treatments.

Optimization of Thermal Neutron Converter in SiC Sensors for Spectral Radiation Measurements

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

Krolikowski, Igor; Cetnar, Jerzy; Issa, Fatima

2015-07-01

Optimization of the neutron converter in SiC sensors is presented. The sensors are used for spectral radiation measurements of thermal and fast neutrons and optionally gamma ray at elevated temperature in harsh radiation environment. The neutron converter, which is based on 10B, allows to detect thermal neutrons by means of neutron capture reaction. Two construction of the sensors were used to measure radiation in experiments. Sensor responses collected in experiments have been reproduced by the computer tool created by authors, it allows to validate the tool. The tool creates the response matrix function describing the characteristic of the sensors andmore » it was used for detailed analyses of the sensor responses. Obtained results help to optimize the neutron converter in order to increase thermal neutron detection. Several enhanced construction of the sensors, which includes the neutron converter based on {sup 10}B or {sup 6}Li, were proposed. (authors)« less

Soft Thermal Sensor with Mechanical Adaptability.

PubMed

Yang, Hui; Qi, Dianpeng; Liu, Zhiyuan; Chandran, Bevita K; Wang, Ting; Yu, Jiancan; Chen, Xiaodong

2016-11-01

A soft thermal sensor with mechanical adaptability is fabricated by the combination of single-wall carbon nanotubes with carboxyl groups and self-healing polymers. This study demonstrates that this soft sensor has excellent thermal response and mechanical adaptability. It shows tremendous promise for improving the service life of soft artificial-intelligence robots and protecting thermally sensitive electronics from the risk of damage by high temperature. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Impact of pulse thermal processing on the properties of inkjet printed metal and flexible sensors

DOE PAGES

Joshi, Pooran C.; Kuruganti, Teja; Killough, Stephen M.

2015-03-11

In this paper, we report on the low temperature processing of environmental sensors employing pulse thermal processing (PTP) technique to define a path toward flexible sensor technology on plastic, paper, and fabric substrates. Inkjet printing and pulse thermal processing technique were used to realize mask-less, additive integration of low-cost sensors on polymeric substrates with specific focus on temperature, humidity, and strain sensors. The printed metal line performance was evaluated in terms of the electrical conductivity characteristics as a function of post-deposition thermal processing conditions. The PTP processed Ag metal lines exhibited high conductivity with metal sheet resistance values below 100more » mΩ/{whitesquare} using a pulse width as short as 250 μs. The flexible temperature and relative humidity sensors were defined on flexible polyimide substrates by direct printing of Ag metal structures. The printed resistive temperature sensor and capacitive humidity sensor were characterized for their sensitivity with focus on future smart-building applications. Strain gauges were printed on polyimide substrate to determine the mechanical properties of the silver nanoparticle films. Finally, the observed electrical properties of the printed metal lines and the sensitivity of the flexible sensors show promise for the realization of a high performance print-on-demand technology exploiting low thermal-budget PTP technique.« less

Theoretical analysis and coating thickness determination of a dual layer metal coated FBG sensor for sensitivity enhancement at cryogenic temperatures

NASA Astrophysics Data System (ADS)

Ramalingam, Rajinikumar; Atrey, M. D.

2017-12-01

Use of Fiber Bragg Grating (FBG) sensor is very appealing for sensing low temperature and strain in superconducting magnets because of their miniature size and the possibility of accommodating many sensors in a single fiber. The main drawback is their low intrinsic thermal sensitivity at low temperatures below 120 K. Approaching cryogenic temperatures, temperature changes lower than a few degrees Kelvin cannot be resolved, since they do not cause an appreciable shift of the wavelength diffracted by a bare FBG sensor. To improve the thermal sensitivity and thermal inertia below 77 K, the Bare FBG (BFBG) sensor can be coated with high thermal expansion coefficient materials. In this work, different metal were considered for coating the FBG sensor. For theoretical investigation, a double layered circular thick wall tube model has been considered to study the effect on sensitivity due to the mechanical properties like Young’s modulus, Thermal expansion coefficient, Poisson’s ratio of selected materials at a various cryogenic temperatures. The primary and the secondary coating thickness for a dual layer metal coated FBG sensor have been determined from the above study. The sensor was then fabricated and tested at cryogenic temperature range from 4-300 K. The cryogenic temperature characteristics of the tested sensors are reported.

Thermal effects of an ICL-based mid-infrared CH 4 sensor within a wide atmospheric temperature range

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

Ye, Weilin; Zheng, Chuantao; Sanchez, Nancy P.

Here, thermal effects of an interband cascade laser (ICL) based mid-infrared methane (CH 4) sensor that uses long-path absorption spectroscopy were studied. The sensor performance in the laboratory at a constant temperature of ~ 25°C was measured for 5 hours and its Allan deviation was ~ 2 ppbv with a 1 s averaging time. A LabVIEW-based simulation program was developed to study thermal effects on infrared absorption and a temperature compensation technique was developed to control such effects. An environmental test chamber was employed to investigate thermal effects that occur in the sensor system with variation of the test chambermore » temperature between 10 and 30°C. The thermal response of the sensor in a laboratory setting was observed using a 2.1 ppm CH 4 standard gas sample. indoor/outdoor CH 4 measurements were conducted to evaluate the sensor performance within a wide atmospheric temperature range.« less

Thermal effects of an ICL-based mid-infrared CH4 sensor within a wide atmospheric temperature range

NASA Astrophysics Data System (ADS)

Ye, Weilin; Zheng, Chuantao; Sanchez, Nancy P.; Girija, Aswathy V.; He, Qixin; Zheng, Huadan; Griffin, Robert J.; Tittel, Frank K.

2018-03-01

The thermal effects of an interband cascade laser (ICL) based mid-infrared methane (CH4) sensor that uses long-path absorption spectroscopy were studied. The sensor performance in the laboratory at a constant temperature of ∼25 °C was measured for 5 h and its Allan deviation was ∼2 ppbv with a 1 s averaging time. A LabVIEW-based simulation program was developed to study thermal effects on infrared absorption and a temperature compensation technique was developed to minimize these effects. An environmental test chamber was employed to investigate the thermal effects that occur in the sensor system with variation of the test chamber temperature between 10 and 30 °C. The thermal response of the sensor in a laboratory setting was observed using a 2.1 ppm CH4 standard gas sample. Indoor/outdoor CH4 measurements were conducted to evaluate the sensor performance within a wide atmospheric temperature range.

Thermal effects of an ICL-based mid-infrared CH 4 sensor within a wide atmospheric temperature range

DOE PAGES

Ye, Weilin; Zheng, Chuantao; Sanchez, Nancy P.; ...

2018-01-31

Here, thermal effects of an interband cascade laser (ICL) based mid-infrared methane (CH 4) sensor that uses long-path absorption spectroscopy were studied. The sensor performance in the laboratory at a constant temperature of ~ 25°C was measured for 5 hours and its Allan deviation was ~ 2 ppbv with a 1 s averaging time. A LabVIEW-based simulation program was developed to study thermal effects on infrared absorption and a temperature compensation technique was developed to control such effects. An environmental test chamber was employed to investigate thermal effects that occur in the sensor system with variation of the test chambermore » temperature between 10 and 30°C. The thermal response of the sensor in a laboratory setting was observed using a 2.1 ppm CH 4 standard gas sample. indoor/outdoor CH 4 measurements were conducted to evaluate the sensor performance within a wide atmospheric temperature range.« less

The use of combined thermal/pressure polyvinylidene fluoride film airflow sensor in polysomnography.

PubMed

Kryger, Meir; Eiken, Todd; Qin, Li

2013-12-01

The technologies recommended by the American Academy of Sleep Medicine (AASM) to monitor airflow in polysomnography (PSG) include the simultaneous monitoring of two physical variables: air temperature (for thermal airflow) and air pressure (for nasal pressure). To comply with airflow monitoring standards in the sleep lab setting thus often requires the patient to wear two sensors under the nose during testing. We hypothesized that a single combined thermal/pressure sensor using polyvinylidene fluoride (PVDF) film responsive to both airflow temperature and pressure would be effective in documenting abnormal breathing events during sleep. Sixty patients undergoing routine PSG testing to rule out obstructive sleep apnea at two different sleep laboratories were asked to wear a third PVDF airflow sensor in addition to the traditional thermal sensor and pressure sensor. Apnea and hypopnea events were scored by the sleep lab technologists using the AASM guidelines (CMS option) using the thermal sensor for apnea and the pressure sensor for hypopnea (scorer 1). The digital PSG data were also forwarded to an outside registered polysomnographic technologist for scoring of respiratory events detected in the PVDF airflow channels (scorer 2). The Pearson correlation coefficient, r, between apnea and hypopnea indices obtained using the AASM sensors and the combined PVDF sensor was almost unity for the four calculated indices: apnea-hypopnea index (0.990), obstructive apnea index (0.992), hypopnea index (0.958), and central apnea index (1.0). The slope of the four relationships was virtually unity and the coefficient of determination (r (2)) was also close to 1. The results of intraclass correlation coefficients (>0.95) and Bland-Altman plots also provide excellent agreement between the combined PVDF sensor and the AASM sensors. The indices used to calculate apnea severity obtained with the combined PVDF thermal and pressure sensor were equivalent to those obtained using AASM-recommended sensors.

Novel wireless sensor system for dynamic characterization of borehole heat exchangers.

PubMed

Martos, Julio; Montero, Álvaro; Torres, José; Soret, Jesús; Martínez, Guillermo; García-Olcina, Raimundo

2011-01-01

The design and field test of a novel sensor system based in autonomous wireless sensors to measure the temperature of the heat transfer fluid along a borehole heat exchanger (BHE) is presented. The system, by means of two special valves, inserts and extracts miniaturized wireless sensors inside the pipes of the borehole, which are carried by the thermal fluid. Each sensor is embedded in a small sphere of just 25 mm diameter and 8 gr weight, containing a transceiver, a microcontroller, a temperature sensor and a power supply. A wireless data processing unit transmits to the sensors the acquisition configuration before the measurements, and also downloads the temperature data measured by the sensor along its way through the BHE U-tube. This sensor system is intended to improve the conventional thermal response test (TRT) and it allows the collection of information about the thermal characteristics of the geological structure of subsurface and its influence in borehole thermal behaviour, which in turn, facilitates the implementation of TRTs in a more cost-effective and reliable way.

Novel Wireless Sensor System for Dynamic Characterization of Borehole Heat Exchangers

PubMed Central

Martos, Julio; Montero, Álvaro; Torres, José; Soret, Jesús; Martínez, Guillermo; García-Olcina, Raimundo

2011-01-01

The design and field test of a novel sensor system based in autonomous wireless sensors to measure the temperature of the heat transfer fluid along a borehole heat exchanger (BHE) is presented. The system, by means of two specials valves, inserts and extracts miniaturized wireless sensors inside the pipes of the borehole, which are carried by the thermal fluid. Each sensor is embedded in a small sphere of just 25 mm diameter and 8 gr weight, containing a transceiver, a microcontroller, a temperature sensor and a power supply. A wireless data processing unit transmits to the sensors the acquisition configuration before the measurements, and also downloads the temperature data measured by the sensor along its way through the BHE U-tube. This sensor system is intended to improve the conventional thermal response test (TRT) and it allows the collection of information about the thermal characteristics of the geological structure of subsurface and its influence in borehole thermal behaviour, which in turn, facilitates the implementation of TRTs in a more cost-effective and reliable way. PMID:22164005

Design and evaluation of a flow-to-frequency converter circuit with thermal feedback

NASA Astrophysics Data System (ADS)

Pawlowski, Eligiusz

2017-05-01

A novel thermal flow sensor with a frequency output is presented. The sensor provides a pulse-train output whose frequency is related to the fluid flow rate around a self-heating thermistor. The integrating properties of the temperature sensor have been used, which allowed for realization of the pulse frequency modulator with a thermal feedback loop, stabilizing the temperature of the sensor placed in the flowing medium. The system assures a balance of the amount of heat supplied in the impulses to the sensor and the heat given up by the sensor in a continuous way to the flowing medium. Therefore the frequency of output pulse-train is proportional to the medium flow velocity around the sensor. The special feature of the presented solution is the total integration of the thermal sensor with the measurement signal conditioning system. i.e. the sensor and conditioning system are not separate elements of the measurement circuit, but constitute a whole in the form of a thermal heat-balance mode flow-to-frequency converter. The frequency signal from the converter may be directly connected to the microprocessor digital input, which with use of the standard built-in counters may convert the frequency into a numerical value of high precision. The sensor has been experimentally characterized as a function of the average flow velocity of air at room temperature.

Robotic Vehicle Communications Interoperability

DTIC Science & Technology

1988-08-01

starter (cold start) X X Fire suppression X Fording control X Fuel control X Fuel tank selector X Garage toggle X Gear selector X X X X Hazard warning...optic Sensors Sensor switch Video Radar IR Thermal imaging system Image intensifier Laser ranger Video camera selector Forward Stereo Rear Sensor control...optic sensors Sensor switch Video Radar IR Thermal imaging system Image intensifier Laser ranger Video camera selector Forward Stereo Rear Sensor

Micromachined Fluid Inertial Sensors

PubMed Central

Liu, Shiqiang; Zhu, Rong

2017-01-01

Micromachined fluid inertial sensors are an important class of inertial sensors, which mainly includes thermal accelerometers and fluid gyroscopes, which have now been developed since the end of the last century for about 20 years. Compared with conventional silicon or quartz inertial sensors, the fluid inertial sensors use a fluid instead of a solid proof mass as the moving and sensitive element, and thus offer advantages of simple structures, low cost, high shock resistance, and large measurement ranges while the sensitivity and bandwidth are not competitive. Many studies and various designs have been reported in the past two decades. This review firstly introduces the working principles of fluid inertial sensors, followed by the relevant research developments. The micromachined thermal accelerometers based on thermal convection have developed maturely and become commercialized. However, the micromachined fluid gyroscopes, which are based on jet flow or thermal flow, are less mature. The key issues and technologies of the thermal accelerometers, mainly including bandwidth, temperature compensation, monolithic integration of tri-axis accelerometers and strategies for high production yields are also summarized and discussed. For the micromachined fluid gyroscopes, improving integration and sensitivity, reducing thermal errors and cross coupling errors are the issues of most concern. PMID:28216569

Thermally Stable, Piezoelectric and Pyroelectric Polymeric Substrates and Method Relating Thereto

NASA Technical Reports Server (NTRS)

Simpson, Joycelyn O. (Inventor); St.Claire, Terry L. (Inventor)

2002-01-01

A thermally stable, piezoelectric and pyroelectric polymeric substrate was prepared, This thermally stable, piezoelectric and pyroelectric polymeric substrate may be used to prepare electromechanical transducers, thermomechanical transducers, accelerometers, acoustic sensors, infrared sensors, pressure sensors, vibration sensors, impact sensors. in-situ temperature sensors, in-situ stress/strain sensors, micro actuators, switches. adjustable fresnel lenses, speakers, tactile sensors, weather sensors, micro positioners, ultrasonic devices, power generators, tunable reflectors, microphones, and hydrophones. The process for preparing these polymeric substrates includes: providing a polymeric substrate having a softening temperature greater than 100 C; depositing a metal electrode material onto the polymer film; attaching a plurality of electrical leads to the metal electrode coated polymeric substrates; heating the metal electrode coated polymeric substrate in a low dielectric medium; applying a voltage to the heated metal electrode coated polymeric substrate to induce polarization; and cooling the polarized metal electrode coated polymeric electrode while maintaining a constant voltage.

Thermally Stable, Piezoelectric and Pyroelectric Polymeric Substrates

NASA Technical Reports Server (NTRS)

Simpson, Joycely O. (Inventor); St.Clair, Terry L. (Inventor)

1999-01-01

A thermally stable, piezoelectric and pyroelectric polymeric substrate was prepared. This thermally stable, piezoelectric and pyroelectric polymeric substrate may be used to prepare electromechanical transducers, thermomechanical transducers, accelerometers. acoustic sensors, infrared sensors, pressure sensors, vibration sensors, impact sensors, in-situ temperature sensors, in-situ stress/strain sensors, micro actuators, switches, adjustable fresnel lenses, speakers, tactile sensors. weather sensors, micro positioners, ultrasonic devices, power generators, tunable reflectors, microphones, and hydrophones. The process for preparing these polymeric substrates includes: providing a polymeric substrate having a softening temperature greater than 1000 C; depositing a metal electrode material onto the polymer film; attaching a plurality of electrical leads to the metal electrode coated polymeric substrate; heating the metal electrode coated polymeric substrate in a low dielectric medium; applying a voltage to the heated metal electrode coated polymeric substrate to induce polarization; and cooling the polarized metal electrode coated polymeric electrode while maintaining a constant voltage.

Method of Making Thermally Stable, Piezoelectric and Proelectric Polymeric Substrates

NASA Technical Reports Server (NTRS)

Simpson, Joycelyn O. (Inventor); St.Clair, Terry L. (Inventor)

1999-01-01

A thermally stable, piezoelectric and pyroelectric polymeric substrate was prepared. This thermally stable, piezoelectric and pyroelectric polymeric substrate may be used to prepare electromechanical transducers, thermomechanical transducers, accelerometers, acoustic sensors, infrared sensors, pressure sensors, vibration sensors, impact sensors. in-situ temperature sensors, in-situ stress/strain sensors, micro actuators, switches, adjustable fresnel lenses, speakers, tactile sensors, weather sensors, micro positioners, ultrasonic devices, power generators, tunable reflectors, microphones, and hydrophones. The process for preparing these polymeric substrates includes: providing a polymeric substrate having a softening temperature greater than 100 C; depositing a metal electrode material onto the polymer film; attaching a plurality of electrical leads to the metal electrode coated polymeric substrate; heating the metal electrode coated polymeric substrate in a low dielectric medium: applying a voltage to the heated metal electrode coated polymeric substrate to induce polarization; and cooling the polarized metal electrode coated polymeric electrode while maintaining a constant voltage.

3D printed high performance strain sensors for high temperature applications

NASA Astrophysics Data System (ADS)

Rahman, Md Taibur; Moser, Russell; Zbib, Hussein M.; Ramana, C. V.; Panat, Rahul

2018-01-01

Realization of high temperature physical measurement sensors, which are needed in many of the current and emerging technologies, is challenging due to the degradation of their electrical stability by drift currents, material oxidation, thermal strain, and creep. In this paper, for the first time, we demonstrate that 3D printed sensors show a metamaterial-like behavior, resulting in superior performance such as high sensitivity, low thermal strain, and enhanced thermal stability. The sensors were fabricated using silver (Ag) nanoparticles (NPs), using an advanced Aerosol Jet based additive printing method followed by thermal sintering. The sensors were tested under cyclic strain up to a temperature of 500 °C and showed a gauge factor of 3.15 ± 0.086, which is about 57% higher than that of those available commercially. The sensor thermal strain was also an order of magnitude lower than that of commercial gages for operation up to a temperature of 500 °C. An analytical model was developed to account for the enhanced performance of such printed sensors based on enhanced lateral contraction of the NP films due to the porosity, a behavior akin to cellular metamaterials. The results demonstrate the potential of 3D printing technology as a pathway to realize highly stable and high-performance sensors for high temperature applications.

A Method to have Multi-Layer Thermal Insulation Provide Damage Detection

NASA Technical Reports Server (NTRS)

Woodward, Stanley E.; Taylor, Bryant D.; Jones, Thomas W.; Shams, Qamar A.; Lyons, Frankel; Henderson, Donald

2007-01-01

Design and testing of a multi-layer thermal insulation system that also provides debris and micrometeorite damage detection is presented. One layer of the insulation is designed as an array of passive open-circuit electrically conductive spiral trace sensors. The sensors are a new class of sensors that are electrically open-circuits that have no electrical connections thereby eliminating one cause of failure to circuits. The sensors are powered using external oscillating magnetic fields. Once electrically active, they produce their own harmonic magnetic fields. The responding field frequency changes if any sensor is damaged. When the sensors are used together in close proximity, the inductive coupling between sensors provides a means of telemetry. The spiral trace design using reflective electrically conductive material provides sufficient area coverage for the sensor array to serves as a layer of thermal insulation. The other insulation layers are designed to allow the sensor s magnetic field to permeate the insulation layers while having total reflective surface area to reduce thermal energy transfer. Results of characterizing individual sensors and the sensor array s response to punctures are presented. Results of hypervelocity impact testing using projectiles of 1-3.6 millimeter diameter having speeds ranging from 6.7-7.1 kilometers per second are also presented.

Variable reluctance proximity sensors for cryogenic valve position indication

NASA Technical Reports Server (NTRS)

Cloyd, R. A.

1982-01-01

A test was conducted to determine the performance of a variable reluctance proximity sensor system when installed in a space shuttle external tank vent/relief valve. The sensors were used as position indicators. The valve and sensors were cycled through a series of thermal transients; while the valve was being opened and closed pneumatically, the sensor's performance was being monitored. During these thermal transients, the vent valve was cooled ten times by liquid nitrogen and two times by liquid hydrogen. It was concluded that the sensors were acceptable replacements for the existing mechanical switches. However, the sensors need a mechanical override for the target similar to what is presently used with the mechanical switches. This override could insure contact between sensor and target and eliminate any problems of actuation gap growth caused by thermal gradients.

Nanometric Integrated Temperature and Thermal Sensors in CMOS-SOI Technology.

PubMed

Malits, Maria; Nemirovsky, Yael

2017-07-29

This paper reviews and compares the thermal and noise characterization of CMOS (complementary metal-oxide-semiconductor) SOI (Silicon on insulator) transistors and lateral diodes used as temperature and thermal sensors. DC analysis of the measured sensors and the experimental results in a broad (300 K up to 550 K) temperature range are presented. It is shown that both sensors require small chip area, have low power consumption, and exhibit linearity and high sensitivity over the entire temperature range. However, the diode's sensitivity to temperature variations in CMOS-SOI technology is highly dependent on the diode's perimeter; hence, a careful calibration for each fabrication process is needed. In contrast, the short thermal time constant of the electrons in the transistor's channel enables measuring the instantaneous heating of the channel and to determine the local true temperature of the transistor. This allows accurate "on-line" temperature sensing while no additional calibration is needed. In addition, the noise measurements indicate that the diode's small area and perimeter causes a high 1/ f noise in all measured bias currents. This is a severe drawback for the sensor accuracy when using the sensor as a thermal sensor; hence, CMOS-SOI transistors are a better choice for temperature sensing.

Thermal Strain Analysis of Optic Fiber Sensors

PubMed Central

Her, Shiuh-Chuan; Huang, Chih-Ying

2013-01-01

An optical fiber sensor surface bonded onto a host structure and subjected to a temperature change is analytically studied in this work. The analysis is developed in order to assess the thermal behavior of an optical fiber sensor designed for measuring the strain in the host structure. For a surface bonded optical fiber sensor, the measuring sensitivity is strongly dependent on the bonding characteristics which include the protective coating, adhesive layer and the bonding length. Thermal stresses can be generated due to a mismatch of thermal expansion coefficients between the optical fiber and host structure. The optical fiber thermal strain induced by the host structure is transferred via the adhesive layer and protective coating. In this investigation, an analytical expression of the thermal strain and stress in the optical fiber is presented. The theoretical predictions are validated using the finite element method. Numerical results show that the thermal strain and stress are linearly dependent on the difference in thermal expansion coefficients between the optical fiber and host structure and independent of the thermal expansion coefficients of the adhesive and coating. PMID:23385407

Thermal design of the hard x-ray imager and the soft gamma-ray detector onboard ASTRO-H

NASA Astrophysics Data System (ADS)

Noda, Hirofumi; Nakazawa, Kazuhiro; Makishima, Kazuo; Iwata, Naoko; Ogawa, Hiroyuki; Ohta, Masayuki; Sato, Goro; Kawaharada, Madoka; Watanabe, Shin; Kokubun, Motohide; Takahashi, Tadayuki; Ohno, Masanori; Fukazawa, Yasushi; Tajima, Hiroyasu; Uchiyama, Hideki; Ito, Shuji; Fukuzawa, Keita

2014-07-01

The Hard X-ray Imager and the Soft Gamma-ray Detector, onboard the 6th Japanese X-ray satellite ASTRO-H, aim at unprecedentedly-sensitive observations in the 5-80 keV and 40-600 keV bands, respectively. Because their main sensors are composed of a number of semi-conductor devices, which need to be operated in a temperature of -20 to -15°C, heat generated in the sensors must be efficiently transported outwards by thermal conduction. For this purpose, we performed thermal design, with the following three steps. First, we additionally included thermally-conductive parts, copper poles and graphite sheets. Second, constructing a thermal mathematical model of the sensors, we estimated temperature distributions in thermal equilibria. Since the model had rather large uncertainties in contact thermal conductions, an accurate thermal dummy was constructed as our final step. Vacuum measurement with the dummy successfully reduced the conductance uncertainties. With these steps, we confirmed that our thermal design of the main sensors satisfies the temperature requirement.

Calibration Assessment of Uncooled Thermal Cameras for Deployment on UAV platforms

NASA Astrophysics Data System (ADS)

Aragon, B.; Parkes, S. D.; Lucieer, A.; Turner, D.; McCabe, M.

2017-12-01

In recent years an array of miniaturized sensors have been developed and deployed on Unmanned Aerial Vehicles (UAVs). Prior to gaining useful data from these integrations, it is vitally important to quantify sensor accuracy, precision and cross-sensitivity of retrieved measurements on environmental variables. Small uncooled thermal frame cameras provide a novel solution to monitoring surface temperatures from UAVs with very high spatial resolution, with retrievals being used to investigate heat stress or evapotranspiration. For these studies, accuracies of a few degrees are generally required. Although radiometrically calibrated thermal cameras have recently become commercially available, confirmation of the accuracy of these sensors is required. Here we detail a system for investigating the accuracy and precision, start up stabilisation time, dependence of retrieved temperatures on ambient temperatures and image vignetting. The calibration system uses a relatively inexpensive blackbody source deployed with the sensor inside an environmental chamber to maintain and control the ambient temperature. Calibration of a number of different thermal sensors commonly used for UAV deployment was investigated. Vignetting was shown to be a major limitation on sensor accuracy, requiring characterization through measuring a spatially uniform temperature target such as the blackbody. Our results also showed that a stabilization period is required after powering on the sensors and before conducting an aerial survey. Through use of the environmental chamber it was shown the ambient temperature influenced the temperatures retrieved by the different sensors. This study illustrates the importance of determining the calibration and cross-sensitivities of thermal sensors to obtain accurate thermal maps that can be used to study crop ecosystems.

Microhotplate Temperature Sensor Calibration and BIST

PubMed Central

Afridi, M.; Montgomery, C.; Cooper-Balis, E.; Semancik, S.; Kreider, K. G.; Geist, J.

2011-01-01

In this paper we describe a novel long-term microhotplate temperature sensor calibration technique suitable for Built-In Self Test (BIST). The microhotplate thermal resistance (thermal efficiency) and the thermal voltage from an integrated platinum-rhodium thermocouple were calibrated against a freshly calibrated four-wire polysilicon microhotplate-heater temperature sensor (heater) that is not stable over long periods of time when exposed to higher temperatures. To stress the microhotplate, its temperature was raised to around 400 °C and held there for days. The heater was then recalibrated as a temperature sensor, and microhotplate temperature measurements were made based on the fresh calibration of the heater, the first calibration of the heater, the microhotplate thermal resistance, and the thermocouple voltage. This procedure was repeated 10 times over a period of 80 days. The results show that the heater calibration drifted substantially during the period of the test while the microhotplate thermal resistance and the thermocouple-voltage remained stable to within about plus or minus 1 °C over the same period. Therefore, the combination of a microhotplate heater-temperature sensor and either the microhotplate thermal resistance or an integrated thin film platinum-rhodium thermocouple can be used to provide a stable, calibrated, microhotplate-temperature sensor, and the combination of the three sensor is suitable for implementing BIST functionality. Alternatively, if a stable microhotplate-heater temperature sensor is available, such as a properly annealed platinum heater-temperature sensor, then the thermal resistance of the microhotplate and the electrical resistance of the platinum heater will be sufficient to implement BIST. It is also shown that aluminum- and polysilicon-based temperature sensors, which are not stable enough for measuring high microhotplate temperatures (>220 °C) without impractically frequent recalibration, can be used to measure the silicon substrate temperature if never exposed to temperatures above about 220 °C. PMID:26989603

Optical thermal sensor based on cholesteric film refilled with mixture of toluene and ethanol.

PubMed

Li, Yong; Liu, Yanjun; Luo, Dan

2017-10-16

We demonstrate an optical thermal sensor based on cholesteric film refilled with mixture of toluene and ethanol. The thermal response mechanism is mainly based on the thermal expansion effect induce by toluene, where the ethanol is used for refractive index adjustment to determine the initial refection band position of cholesteric film. The ethanol-toluene mixture was used to adjust the color tunability with the temperature in relation with the habits of people (blue as cold, green as safe and red as hot). A broad temperature range of 86 °C and highly sensitivity of 1.79 nm/ °C are achieved in proposed thermal sensor, where the reflective color red-shifts from blue to red when environmental temperature increases from -6 °C to 80 °C. This battery-free thermal sensor possesses features including simple fabrication, low-cost, and broad temperature sensing range, showing potential application in scientific research and industry.

Thermal sensor with an improved coating

DOEpatents

LaDelfe, P.C.; Stotlar, S.C.

1984-03-30

The disclosure is directed to an apparatus for detecting radiation having wavelengths from about 0.4 ..mu..m to about 5.6 ..mu..m. An optical coating is applied to a thermal sensor that is normally transparent to radiation with such wavelengths. The optical coating is thin and light and includes a modifier and an absorber. The thermal sensor can be a pyroelectric detector such as strontium barium niobate.

Thermal sensor with an improved coating

DOEpatents

LaDelfe, Peter C.; Stotlar, Suzanne C.

1986-01-01

The disclosure is directed to an apparatus for detecting radiation having wavelengths from about 0.4 .mu.m to about 5.6 .mu.m. An optical coating is applied to a thermal sensor that is normally transparent to radiation with such wavelengths. The optical coating is thin and light and includes a modifier and an absorber. The thermal sensor can be a pyroelectric detector such as strontium barium niobate.

A Real-Time Thermal Self-Elimination Method for Static Mode Operated Freestanding Piezoresistive Microcantilever-Based Biosensors.

PubMed

Ku, Yu-Fu; Huang, Long-Sun; Yen, Yi-Kuang

2018-02-28

Here, we provide a method and apparatus for real-time compensation of the thermal effect of single free-standing piezoresistive microcantilever-based biosensors. The sensor chip contained an on-chip fixed piezoresistor that served as a temperature sensor, and a multilayer microcantilever with an embedded piezoresistor served as a biomolecular sensor. This method employed the calibrated relationship between the resistance and the temperature of piezoresistors to eliminate the thermal effect on the sensor, including the temperature coefficient of resistance (TCR) and bimorph effect. From experimental results, the method was verified to reduce the signal of thermal effect from 25.6 μV/°C to 0.3 μV/°C, which was approximately two orders of magnitude less than that before the processing of the thermal elimination method. Furthermore, the proposed approach and system successfully demonstrated its effective real-time thermal self-elimination on biomolecular detection without any thermostat device to control the environmental temperature. This method realizes the miniaturization of an overall measurement system of the sensor, which can be used to develop portable medical devices and microarray analysis platforms.

Effect of heater geometry and cavity volume on the sensitivity of a thermal convection-based tilt sensor

NASA Astrophysics Data System (ADS)

Han, Maeum; Keon Kim, Jae; Kong, Seong Ho; Kang, Shin-Won; Jung, Daewoong

2018-06-01

This paper reports a micro-electro-mechanical-system (MEMS)-based tilt sensor using air medium. Since the working mechanism of the sensor is the thermal convection in a sealed chamber, structural parameters that can affect thermal convection must be considered to optimize the performance of the sensor. This paper presents the experimental results that were conducted by optimizing several parameters such as the heater geometry, input power and cavity volume. We observed that an increase in the heating power and cavity volume can improve the sensitivity, and heater geometry plays important role in performance of the sensor.

Experimental design for the evaluation of high-T(sub c) superconductive thermal bridges in a sensor satellite

NASA Technical Reports Server (NTRS)

Scott, Elaine P.; Lee, Kasey M.

1994-01-01

Infrared sensor satellites, which consist of cryogenic infrared sensor detectors, electrical instrumentation, and data acquisition systems, are used to monitor the conditions of the earth's upper atmosphere in order to evaluate its present and future changes. Currently, the electrical connections (instrumentation), which act as thermal bridges between the cryogenic infrared sensor and the significantly warmer data acquisition unit of the sensor satellite system, constitute a significant portion of the heat load on the cryogen. As a part of extending the mission life of the sensor satellite system, the researchers at the National Aeronautics and Space Administration's Langley Research Center (NASA-LaRC) are evaluating the effectiveness of replacing the currently used manganin wires with high-temperature superconductive (HTS) materials as the electrical connections (thermal bridges). In conjunction with the study being conducted at NASA-LaRC, the proposed research is to design a space experiment to determine the thermal savings on a cryogenic subsystem when manganin leads are replaced by HTS leads printed onto a substrate with a low thermal conductivity, and to determine the thermal conductivities of HTS materials. The experiment is designed to compare manganin wires with two different types of superconductors on substrates by determining the heat loss by the thermal bridges and providing temperature measurements for the estimation of thermal conductivity. A conductive mathematical model has been developed and used as a key tool in the design process and subsequent analysis.

Fabrication of ZnO/SnO2 hierarchical structures as the composite photoanodes for efficient CdS/CdSe co-sensitized solar cells

NASA Astrophysics Data System (ADS)

Lin, Yibing; Lin, Yu; Wu, Jihuai; Zhang, Xiaolong; Fang, Biaopeng

2017-03-01

The composite photoanodes based on the ZnO/SnO2 hierarchical structures with high photoelectricity properties have been successfully synthesized, and used in the CdS and CdSe quantum dots co-sensitized solar cells (QDSSCs). In this experiment, the ZnO/SnO2 nanoparticles (ZS-NP) and hierarchical nanosheets-based microflowers (ZS-MF) were prepared by the one-step hydrothermal route and the morphologies of the products were controlled by the solvent variation. An improved power conversion efficiency of 4.98% was achieved for the cell based on the ZS-MF composite photoanodes, which showed an increase of 21.8% compared to the ZS-NP photoanodes (4.09%). This result is mainly connected to the unique superiority of the three-dimensional hierarchical microflower nanostructures for light scattering and quantum dots loading, which is responsible for the increase of photocurrent values and eventual PCE.

Primary standards for measuring flow rates from 100 nl/min to 1 ml/min - gravimetric principle.

PubMed

Bissig, Hugo; Petter, Harm Tido; Lucas, Peter; Batista, Elsa; Filipe, Eduarda; Almeida, Nelson; Ribeiro, Luis Filipe; Gala, João; Martins, Rui; Savanier, Benoit; Ogheard, Florestan; Niemann, Anders Koustrup; Lötters, Joost; Sparreboom, Wouter

2015-08-01

Microflow and nanoflow rate calibrations are important in several applications such as liquid chromatography, (scaled-down) process technology, and special health-care applications. However, traceability in the microflow and nanoflow range does not go below 16 μl/min in Europe. Furthermore, the European metrology organization EURAMET did not yet validate this traceability by means of an intercomparison between different National Metrology Institutes (NMIs). The NMIs METAS, Centre Technique des Industries Aérauliques et Thermiques, IPQ, Danish Technological Institute, and VSL have therefore developed and validated primary standards to cover the flow rate range from 0.1 μl/min to at least 1 ml/min. In this article, we describe the different designs and methods of the primary standards of the gravimetric principle and the results obtained at the intercomparison for the upper flow rate range for the various NMIs and Bronkhorst High-Tech, the manufacturer of the transfer standards used.

Porous Graphene Microflowers for High-Performance Microwave Absorption

NASA Astrophysics Data System (ADS)

Chen, Chen; Xi, Jiabin; Zhou, Erzhen; Peng, Li; Chen, Zichen; Gao, Chao

2018-06-01

Graphene has shown great potential in microwave absorption (MA) owing to its high surface area, low density, tunable electrical conductivity and good chemical stability. To fully realize graphene's MA ability, the microstructure of graphene should be carefully addressed. Here we prepared graphene microflowers (Gmfs) with highly porous structure for high-performance MA filler material. The efficient absorption bandwidth (reflection loss ≤ -10 dB) reaches 5.59 GHz and the minimum reflection loss is up to -42.9 dB, showing significant increment compared with stacked graphene. Such performance is higher than most graphene-based materials in the literature. Besides, the low filling content (10 wt%) and low density (40-50 mg cm-3) are beneficial for the practical applications. Without compounding with magnetic materials or conductive polymers, Gmfs show outstanding MA performance with the aid of rational microstructure design. Furthermore, Gmfs exhibit advantages in facile processibility and large-scale production compared with other porous graphene materials including aerogels and foams.

Multifunctional luminescent nanomaterials from NaLa(MoO4)2:Eu3+/Tb3+ with tunable decay lifetimes, emission colors, and enhanced cell viability

PubMed Central

Yang, Mei; Liang, Youlong; Gui, Qingyuan; Zhao, Bingxin; Jin, Dayong; Lin, Mimi; Yan, Lu; You, Hongpeng; Dai, Liming; Liu, Yong

2015-01-01

A facile, but effective, method has been developed for large-scale preparation of NaLa(MoO4)2 nanorods and microflowers co-doped with Eu3+ and Tb3+ ions (abbreviated as: NLM:Ln3+). The as-synthesized nanomaterials possess a pure tetragonal phase with variable morphologies from shuttle-like nanorods to microflowers by controlling the reaction temperature and the amount of ethylene glycol used. Consequently, the resulting nanomaterials exhibit superb luminescent emissions over the visible region from red through yellow to green by simply changing the relative doping ratios of Eu3+ to Tb3+ ions. Biocompatibility study indicates that the addition of NLM:Ln3+ nanomaterials can stimulate the growth of normal human retinal pigment epithelium (ARPE-19) cells. Therefore, the newly-developed NaLa(MoO4)2 nanomaterials hold potentials for a wide range of multifunctional applications, including bioimaging, security protection, optical display, optoelectronics for information storage, and cell stimulation. PMID:26259515

Performance evaluation of a conformal thermal monitoring sheet (TMS) sensor array for measurement of surface temperature distributions during superficial hyperthermia treatments

PubMed Central

Arunachalam, K.; Maccarini, P.; Juang, T.; Gaeta, C.; Stauffer, P. R.

2009-01-01

Purpose This paper presents a novel conformal thermal monitoring sheet sensor array with differential thermal sensitivity for measuring temperature distributions over large surface areas. Performance of the sensor array is evaluated in terms of thermal accuracy, mechanical stability and conformity to contoured surfaces, probe self heating under irradiation from microwave and ultrasound hyperthermia sources, and electromagnetic field perturbation. Materials and Methods A prototype TMS with 4×4 array of fiberoptic sensors embedded between two flexible and thermally conducting polyimide films was developed as an alternative to the standard 1-2 mm diameter plastic catheter based probes used in clinical hyperthermia. Computed tomography images and bending tests were performed to evaluate the conformability and mechanical stability respectively. Irradiation and thermal barrier tests were conducted and thermal response of the prototype was compared with round cross-sectional clinical probes. Results Bending and conformity tests demonstrated higher flexibility, dimensional stability and close conformity to human torso. Minimal perturbation of microwave fields and low probe self heating was observed when irradiated with 915MHz microwave and 3.4MHz ultrasound sources. The transient and steady state thermal responses of the TMS array were superior compared to the clinical probes. Conclusions A conformal TMS sensor array with improved thermal sensitivity and dimensional stability was investigated for real-time skin temperature monitoring. This fixed-geometry, body-conforming array of thermal sensors allows fast and accurate characterization of two-dimensional temperature distributions over large surface areas. The prototype TMS demonstrates significant advantages over clinical probes for characterizing skin temperature distributions during hyperthermia treatments of superficial tissue disease. PMID:18465416

Thermal Curing Process Monitoring of the Composite Material Using the FBG sensor

NASA Astrophysics Data System (ADS)

Zhang, Youhong; Chang, Xinlong; Zhang, Xiaojun; He, Xiangyong

2018-03-01

The raw composite material will suffer complex chemical and morphological changes during the thermal curing process, and it is difficult to monitor the curing process and curing effect. In this paper, the FBG sensor was embedded in the raw composite material to monitor the whole curing process. The experiment results showed that the FBG sensor can monitor the resin transformation and residual deformation of the composite material, and the FBG sensor can be applied to monitor the thermal curing process of the composite structure.

Depth and thermal sensor fusion to enhance 3D thermographic reconstruction.

PubMed

Cao, Yanpeng; Xu, Baobei; Ye, Zhangyu; Yang, Jiangxin; Cao, Yanlong; Tisse, Christel-Loic; Li, Xin

2018-04-02

Three-dimensional geometrical models with incorporated surface temperature data provide important information for various applications such as medical imaging, energy auditing, and intelligent robots. In this paper we present a robust method for mobile and real-time 3D thermographic reconstruction through depth and thermal sensor fusion. A multimodal imaging device consisting of a thermal camera and a RGB-D sensor is calibrated geometrically and used for data capturing. Based on the underlying principle that temperature information remains robust against illumination and viewpoint changes, we present a Thermal-guided Iterative Closest Point (T-ICP) methodology to facilitate reliable 3D thermal scanning applications. The pose of sensing device is initially estimated using correspondences found through maximizing the thermal consistency between consecutive infrared images. The coarse pose estimate is further refined by finding the motion parameters that minimize a combined geometric and thermographic loss function. Experimental results demonstrate that complimentary information captured by multimodal sensors can be utilized to improve performance of 3D thermographic reconstruction. Through effective fusion of thermal and depth data, the proposed approach generates more accurate 3D thermal models using significantly less scanning data.

Active thermal isolation for temperature responsive sensors

NASA Technical Reports Server (NTRS)

Martinson, Scott D. (Inventor); Gray, David L. (Inventor); Carraway, Debra L. (Inventor); Reda, Daniel C. (Inventor)

1994-01-01

The detection of flow transition between laminar and turbulent flow and of shear stress or skin friction of airfoils is important in basic research for validation of airfoil theory and design. These values are conventionally measured using hot film nickel sensors deposited on a polyimide substrate. The substrate electrically insulates the sensor and underlying airfoil but is prevented from thermally isolating the sensor by thickness constraints necessary to avoid flow contamination. Proposed heating of the model surface is difficult to control, requires significant energy expenditures, and may alter the basic flow state of the airfoil. A temperature responsive sensor is located in the airflow over the specified surface of a body and is maintained at a constant temperature. An active thermal isolator is located between this temperature responsive sensor and the specific surface of the body. The total thickness of the isolator and sensor avoid any contamination of the flow. The temperature of this isolator is controlled to reduce conductive heat flow from the temperature responsive sensor to the body. This temperature control includes (1) operating the isolator at the same temperature as the constant temperature of the sensor; and (2) establishing a fixed boundary temperature which is either less than or equal to, or slightly greater than the sensor constant temperature. The present invention accordingly thermally isolates a temperature responsive sensor in an energy efficient, controllable manner while avoiding any contamination of the flow.

Thermal heat-balance mode flow-to-frequency converter

NASA Astrophysics Data System (ADS)

Pawlowski, Eligiusz

2016-11-01

This paper presents new type of thermal flow converter with the pulse frequency output. The integrating properties of the temperature sensor have been used, which allowed for realization of pulse frequency modulator with thermal feedback loop, stabilizing temperature of sensor placed in the flowing medium. The system assures balancing of heat amount supplied in impulses to the sensor and heat given up by the sensor in a continuous way to the flowing medium. Therefore the frequency of output impulses is proportional to the heat transfer coefficient from sensor to environment. According to the King's law, the frequency of those impulses is a function of medium flow velocity around the sensor. The special feature of presented solution is total integration of thermal sensor with the measurement signal conditioning system. Sensor and conditioning system are not the separate elements of the measurement circuit, but constitute a whole in form of thermal heat-balance mode flow-to-frequency converter. The advantage of such system is easiness of converting the frequency signal to the digital form, without using any additional analogue-to-digital converters. The frequency signal from the converter may be directly connected to the microprocessor input, which with use of standard built-in counters may convert the frequency into numerical value of high precision. Moreover, the frequency signal has higher resistance to interference than the voltage signal and may be transmitted to remote locations without the information loss.

Analysis, compensation, and correction of temperature effects on FBG strain sensors

NASA Astrophysics Data System (ADS)

Haber, T. C.; Ferguson, S.; Guthrie, D.; Graver, T. W.; Soller, B. J.; Mendez, Alexis

2013-05-01

One of the most common fiber optic sensor (FOS) types used are fiber Bragg gratings (FBG), and the most frequently measured parameter is strain. Hence, FBG strain sensors are one of the most prevalent FOS devices in use today in structural sensing and monitoring in civil engineering, aerospace, marine, oil and gas, composites and smart structure applications. However, since FBGs are simultaneously sensitive to both temperature and strain, it becomes essential to utilize sensors that are either fully temperature insensitive or, alternatively, properly temperature compensated to avoid erroneous measurements. In this paper, we introduce the concept of measured "total strain", which is inherent and unique to optical strain sensors. We review and analyze the temperature and strain sensitivities of FBG strain sensors and decompose the total measured strain into thermal and non-thermal components. We explore the differences between substrate CTE and System Thermal Response Coefficients, which govern the type and quality of thermal strain decomposition analysis. Finally, we present specific guidelines to achieve proper temperature-insensitive strain measurements by combining adequate installation, sensor packaging and data correction techniques.

n+ GaAs/AuGeNi-Au Thermocouple-Type RF MEMS Power Sensors Based on Dual Thermal Flow Paths in GaAs MMIC

PubMed Central

Zhang, Zhiqiang; Liao, Xiaoping

2017-01-01

To achieve radio frequency (RF) power detection, gain control, and circuit protection, this paper presents n+ GaAs/AuGeNi-Au thermocouple-type RF microelectromechanical system (MEMS) power sensors based on dual thermal flow paths. The sensors utilize a conversion principle of RF power-heat-voltage, where a thermovoltage is obtained as the RF power changes. To improve the heat transfer efficiency and the sensitivity, structures of two heat conduction paths are designed: one in which a thermal slug of Au is placed between two load resistors and hot junctions of the thermocouples, and one in which a back cavity is fabricated by the MEMS technology to form a substrate membrane underneath the resistors and the hot junctions. The improved sensors were fabricated by a GaAs monolithic microwave integrated circuit (MMIC) process. Experiments show that these sensors have reflection losses of less than −17 dB up to 12 GHz. At 1, 5, and 10 GHz, measured sensitivities are about 63.45, 53.97, and 44.14 µV/mW for the sensor with the thermal slug, and about 111.03, 94.79, and 79.04 µV/mW for the sensor with the thermal slug and the back cavity, respectively. PMID:28629144

Nanometric Integrated Temperature and Thermal Sensors in CMOS-SOI Technology

PubMed Central

Malits, Maria; Nemirovsky, Yael

2017-01-01

This paper reviews and compares the thermal and noise characterization of CMOS (complementary metal-oxide-semiconductor) SOI (Silicon on insulator) transistors and lateral diodes used as temperature and thermal sensors. DC analysis of the measured sensors and the experimental results in a broad (300 K up to 550 K) temperature range are presented. It is shown that both sensors require small chip area, have low power consumption, and exhibit linearity and high sensitivity over the entire temperature range. However, the diode’s sensitivity to temperature variations in CMOS-SOI technology is highly dependent on the diode’s perimeter; hence, a careful calibration for each fabrication process is needed. In contrast, the short thermal time constant of the electrons in the transistor’s channel enables measuring the instantaneous heating of the channel and to determine the local true temperature of the transistor. This allows accurate “on-line” temperature sensing while no additional calibration is needed. In addition, the noise measurements indicate that the diode’s small area and perimeter causes a high 1/f noise in all measured bias currents. This is a severe drawback for the sensor accuracy when using the sensor as a thermal sensor; hence, CMOS-SOI transistors are a better choice for temperature sensing. PMID:28758932

n⁺ GaAs/AuGeNi-Au Thermocouple-Type RF MEMS Power Sensors Based on Dual Thermal Flow Paths in GaAs MMIC.

PubMed

Zhang, Zhiqiang; Liao, Xiaoping

2017-06-17

To achieve radio frequency (RF) power detection, gain control, and circuit protection, this paper presents n⁺ GaAs/AuGeNi-Au thermocouple-type RF microelectromechanical system (MEMS) power sensors based on dual thermal flow paths. The sensors utilize a conversion principle of RF power-heat-voltage, where a thermovoltage is obtained as the RF power changes. To improve the heat transfer efficiency and the sensitivity, structures of two heat conduction paths are designed: one in which a thermal slug of Au is placed between two load resistors and hot junctions of the thermocouples, and one in which a back cavity is fabricated by the MEMS technology to form a substrate membrane underneath the resistors and the hot junctions. The improved sensors were fabricated by a GaAs monolithic microwave integrated circuit (MMIC) process. Experiments show that these sensors have reflection losses of less than -17 dB up to 12 GHz. At 1, 5, and 10 GHz, measured sensitivities are about 63.45, 53.97, and 44.14 µ V/mW for the sensor with the thermal slug, and about 111.03, 94.79, and 79.04 µ V/mW for the sensor with the thermal slug and the back cavity, respectively.

Micromachined Chip Scale Thermal Sensor for Thermal Imaging.

PubMed

Shekhawat, Gajendra S; Ramachandran, Srinivasan; Jiryaei Sharahi, Hossein; Sarkar, Souravi; Hujsak, Karl; Li, Yuan; Hagglund, Karl; Kim, Seonghwan; Aden, Gary; Chand, Ami; Dravid, Vinayak P

2018-02-27

The lateral resolution of scanning thermal microscopy (SThM) has hitherto never approached that of mainstream atomic force microscopy, mainly due to poor performance of the thermal sensor. Herein, we report a nanomechanical system-based thermal sensor (thermocouple) that enables high lateral resolution that is often required in nanoscale thermal characterization in a wide range of applications. This thermocouple-based probe technology delivers excellent lateral resolution (∼20 nm), extended high-temperature measurements >700 °C without cantilever bending, and thermal sensitivity (∼0.04 °C). The origin of significantly improved figures-of-merit lies in the probe design that consists of a hollow silicon tip integrated with a vertically oriented thermocouple sensor at the apex (low thermal mass) which interacts with the sample through a metallic nanowire (50 nm diameter), thereby achieving high lateral resolution. The efficacy of this approach to SThM is demonstrated by imaging embedded metallic nanostructures in silica core-shell, metal nanostructures coated with polymer films, and metal-polymer interconnect structures. The nanoscale pitch and extremely small thermal mass of the probe promise significant improvements over existing methods and wide range of applications in several fields including semiconductor industry, biomedical imaging, and data storage.

Fabrication and Performance of MEMS-Based Pressure Sensor Packages Using Patterned Ultra-Thick Photoresists

PubMed Central

Chen, Lung-Tai; Chang, Jin-Sheng; Hsu, Chung-Yi; Cheng, Wood-Hi

2009-01-01

A novel plastic packaging of a piezoresistive pressure sensor using a patterned ultra-thick photoresist is experimentally and theoretically investigated. Two pressure sensor packages of the sacrifice-replacement and dam-ring type were used in this study. The characteristics of the packaged pressure sensors were investigated by using a finite-element (FE) model and experimental measurements. The results show that the thermal signal drift of the packaged pressure sensor with a small sensing-channel opening or with a thin silicon membrane for the dam-ring approach had a high packaging induced thermal stress, leading to a high temperature coefficient of span (TCO) response of −0.19% span/°C. The results also show that the thermal signal drift of the packaged pressure sensors with a large sensing-channel opening for sacrifice-replacement approach significantly reduced packaging induced thermal stress, and hence a low TCO response of −0.065% span/°C. However, the packaged pressure sensors of both the sacrifice-replacement and dam-ring type still met the specification −0.2% span/°C of the unpackaged pressure sensor. In addition, the size of proposed packages was 4 × 4 × 1.5 mm3 which was about seven times less than the commercialized packages. With the same packaging requirement, the proposed packaging approaches may provide an adequate solution for use in other open-cavity sensors, such as gas sensors, image sensors, and humidity sensors. PMID:22454580

Liquid-Sensing Probe and Methods for Using the Same

NASA Technical Reports Server (NTRS)

Haberbusch, Mark S. (Inventor); Ickes, Jacob C. (Inventor); Thurn, Adam (Inventor); Lawless, Branden J. (Inventor)

2014-01-01

A sensor assembly includes a main body, a sensor, and a filler. The main body includes an outer surface having a continuously-variable radius of curvature in at least one portion. A sensor in thermal communication with a region of that surface having relatively low radius of curvature is disposed in the assembly recessed from the outer surface. Liquid droplets adhered to the outer surface in this region tend to migrate to a distant location having a higher radius of curvature. The main body has low thermal conductivity. The filler has a relatively higher thermal conductivity and, in embodiments, fills an opening in the outer surface of the main body, providing a thermally-conductive pathway between the sensor and the surrounding environment via the opening. A probe having a plurality of such sensors, and methods of detecting the presence of liquid and phase transitions in a predetermined space are also disclosed.

Target Detection over the Diurnal Cycle Using a Multispectral Infrared Sensor.

PubMed

Zhao, Huijie; Ji, Zheng; Li, Na; Gu, Jianrong; Li, Yansong

2016-12-29

When detecting a target over the diurnal cycle, a conventional infrared thermal sensor might lose the target due to the thermal crossover, which could happen at any time throughout the day when the infrared image contrast between target and background in a scene is indistinguishable due to the temperature variation. In this paper, the benefits of using a multispectral-based infrared sensor over the diurnal cycle have been shown. Firstly, a brief theoretical analysis on how the thermal crossover influences a conventional thermal sensor, within the conditions where the thermal crossover would happen and why the mid-infrared (3~5 μm) multispectral technology is effective, is presented. Furthermore, the effectiveness of this technology is also described and we describe how the prototype design and multispectral technology is employed to help solve the thermal crossover detection problem. Thirdly, several targets are set up outside and imaged in the field experiment over a 24-h period. The experimental results show that the multispectral infrared imaging system can enhance the contrast of the detected images and effectively solve the failure of the conventional infrared sensor during the diurnal cycle, which is of great significance for infrared surveillance applications.

A Real-Time Thermal Self-Elimination Method for Static Mode Operated Freestanding Piezoresistive Microcantilever-Based Biosensors

PubMed Central

Ku, Yu-Fu; Huang, Long-Sun

2018-01-01

Here, we provide a method and apparatus for real-time compensation of the thermal effect of single free-standing piezoresistive microcantilever-based biosensors. The sensor chip contained an on-chip fixed piezoresistor that served as a temperature sensor, and a multilayer microcantilever with an embedded piezoresistor served as a biomolecular sensor. This method employed the calibrated relationship between the resistance and the temperature of piezoresistors to eliminate the thermal effect on the sensor, including the temperature coefficient of resistance (TCR) and bimorph effect. From experimental results, the method was verified to reduce the signal of thermal effect from 25.6 μV/°C to 0.3 μV/°C, which was approximately two orders of magnitude less than that before the processing of the thermal elimination method. Furthermore, the proposed approach and system successfully demonstrated its effective real-time thermal self-elimination on biomolecular detection without any thermostat device to control the environmental temperature. This method realizes the miniaturization of an overall measurement system of the sensor, which can be used to develop portable medical devices and microarray analysis platforms. PMID:29495574

Target Detection over the Diurnal Cycle Using a Multispectral Infrared Sensor

PubMed Central

Zhao, Huijie; Ji, Zheng; Li, Na; Gu, Jianrong; Li, Yansong

2016-01-01

When detecting a target over the diurnal cycle, a conventional infrared thermal sensor might lose the target due to the thermal crossover, which could happen at any time throughout the day when the infrared image contrast between target and background in a scene is indistinguishable due to the temperature variation. In this paper, the benefits of using a multispectral-based infrared sensor over the diurnal cycle have been shown. Firstly, a brief theoretical analysis on how the thermal crossover influences a conventional thermal sensor, within the conditions where the thermal crossover would happen and why the mid-infrared (3~5 μm) multispectral technology is effective, is presented. Furthermore, the effectiveness of this technology is also described and we describe how the prototype design and multispectral technology is employed to help solve the thermal crossover detection problem. Thirdly, several targets are set up outside and imaged in the field experiment over a 24-h period. The experimental results show that the multispectral infrared imaging system can enhance the contrast of the detected images and effectively solve the failure of the conventional infrared sensor during the diurnal cycle, which is of great significance for infrared surveillance applications. PMID:28036073

New portable instrument for the measurement of thermal conductivity in gas process conditions

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

Queirós, C. S. G. P.; Lourenço, M. J. V., E-mail: mjlourenco@fc.ul.pt; Vieira, S. I.

The development of high temperature gas sensors for the monitoring and determination of thermophysical properties of complex process mixtures at high temperatures faces several problems, related with the materials compatibility, active sensing parts sensitivity, and lifetime. Ceramic/thin metal films based sensors, previously developed for the determination of thermal conductivity of molten materials up to 1200 °C, were redesigned, constructed, and applied for thermal conductivity measuring sensors. Platinum resistance thermometers were also developed using the same technology, to be used in the temperature measurement, which were also constructed and tested. A new data acquisition system for the thermal conductivity sensors, based onmore » a linearization of the transient hot-strip model, including a portable electronic bridge for the measurement of the thermal conductivity in gas process conditions was also developed. The equipment is capable of measuring the thermal conductivity of gaseous phases with an accuracy of 2%-5% up to 840 °C (95% confidence level). The development of sensors up to 1200 °C, present at the core of the combustion chambers, will be done in a near future.« less

A Low-Power Thermal-Based Sensor System for Low Air Flow Detection

PubMed Central

Arifuzzman, AKM; Haider, Mohammad Rafiqul; Allison, David B.

2016-01-01

Being able to rapidly detect a low air flow rate with high accuracy is essential for various applications in the automotive and biomedical industries. We have developed a thermal-based low air flow sensor with a low-power sensor readout for biomedical applications. The thermal-based air flow sensor comprises a heater and three pairs of temperature sensors that sense temperature differences due to laminar air flow. The thermal-based flow sensor was designed and simulated by using laminar flow, heat transfer in solids and fluids physics in COMSOL MultiPhysics software. The proposed sensor can detect air flow as low as 0.0064 m/sec. The readout circuit is based on a current- controlled ring oscillator in which the output frequency of the ring oscillator is proportional to the temperature differences of the sensors. The entire readout circuit was designed and simulated by using a 130-nm standard CMOS process. The sensor circuit features a small area and low-power consumption of about 22.6 µW with an 800 mV power supply. In the simulation, the output frequency of the ring oscillator and the change in thermistor resistance showed a high linearity with an R2 value of 0.9987. The low-power dissipation, high linearity and small dimensions of the proposed flow sensor and circuit make the system highly suitable for biomedical applications. PMID:28435186

Investigation of MIS-sensor sensitivity to vapor of unsymmetrical dimethylgydrazine in air

NASA Astrophysics Data System (ADS)

Filipchuk, D. V.; Litvinov, A. V.; Etrekova, M. O.; Nozdrya, D. A.

2018-01-01

The sensitivity of MIS-sensor to the products of thermal decomposition of unsymmetrical dimethylhydrazine was investigated. It is shown that MIS sensor is able to detect the concentrations of the test substance by the means of the certain products of its thermal decomposition (ammonia and nitric dioxide).

Tracking heat flux sensors for concentrating solar applications

DOEpatents

Andraka, Charles E; Diver, Jr., Richard B

2013-06-11

Innovative tracking heat flux sensors located at or near the solar collector's focus for centering the concentrated image on a receiver assembly. With flux sensors mounted near a receiver's aperture, the flux gradient near the focus of a dish or trough collector can be used to precisely position the focused solar flux on the receiver. The heat flux sensors comprise two closely-coupled thermocouple junctions with opposing electrical polarity that are separated by a thermal resistor. This arrangement creates an electrical signal proportional to heat flux intensity, and largely independent of temperature. The sensors are thermally grounded to allow a temperature difference to develop across the thermal resistor, and are cooled by a heat sink to maintain an acceptable operating temperature.

Fabrication of amorphous InGaZnO thin-film transistor-driven flexible thermal and pressure sensors

NASA Astrophysics Data System (ADS)

Park, Ick-Joon; Jeong, Chan-Yong; Cho, In-Tak; Lee, Jong-Ho; Cho, Eou-Sik; Kwon, Sang Jik; Kim, Bosul; Cheong, Woo-Seok; Song, Sang-Hun; Kwon, Hyuck-In

2012-10-01

In this work, we present the results concerning the use of amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) as a driving transistor of the flexible thermal and pressure sensors which are applicable to artificial skin systems. Although the a-IGZO TFT has been attracting much attention as a driving transistor of the next-generation flat panel displays, no study has been performed about the application of this new device to the driving transistor of the flexible sensors yet. The proposed thermal sensor pixel is composed of the series-connected a-IGZO TFT and ZnO-based thermistor fabricated on a polished metal foil, and the ZnO-based thermistor is replaced by the pressure sensitive rubber in the pressure sensor pixel. In both sensor pixels, the a-IGZO TFT acts as the driving transistor and the temperature/pressure-dependent resistance of the ZnO-based thermistor/pressure-sensitive rubber mainly determines the magnitude of the output currents. The fabricated a-IGZO TFT-driven flexible thermal sensor shows around a seven times increase in the output current as the temperature increases from 20 °C to 100 °C, and the a-IGZO TFT-driven flexible pressure sensors also exhibit high sensitivity under various pressure environments.

High-Temperature Optical Sensor

NASA Technical Reports Server (NTRS)

Adamovsky, Grigory; Juergens, Jeffrey R.; Varga, Donald J.; Floyd, Bertram M.

2010-01-01

A high-temperature optical sensor (see Figure 1) has been developed that can operate at temperatures up to 1,000 C. The sensor development process consists of two parts: packaging of a fiber Bragg grating into a housing that allows a more sturdy thermally stable device, and a technological process to which the device is subjected to in order to meet environmental requirements of several hundred C. This technology uses a newly discovered phenomenon of the formation of thermally stable secondary Bragg gratings in communication-grade fibers at high temperatures to construct robust, optical, high-temperature sensors. Testing and performance evaluation (see Figure 2) of packaged sensors demonstrated operability of the devices at 1,000 C for several hundred hours, and during numerous thermal cycling from 400 to 800 C with different heating rates. The technology significantly extends applicability of optical sensors to high-temperature environments including ground testing of engines, flight propulsion control, thermal protection monitoring of launch vehicles, etc. It may also find applications in such non-aerospace arenas as monitoring of nuclear reactors, furnaces, chemical processes, and other hightemperature environments where other measurement techniques are either unreliable, dangerous, undesirable, or unavailable.

An Electromagnetic/Capacitive Composite Sensor for Testing of Thermal Barrier Coatings

PubMed Central

Ren, Yuan; Pan, Mengchun; Chen, Dixiang; Tian, Wugang

2018-01-01

Thermal barrier coatings (TBCs) can significantly reduce the operating temperature of the aeroengine turbine blade substrate, and their testing technology is very urgently demanded. Due to their complex multi-layer structure, it is hard to evaluate TBCs with a single function sensor. In this paper, an electromagnetic/capacitive composite sensor is proposed for the testing of thermal barrier coatings. The dielectric material is tested with planar capacitor, and the metallic material is tested with electromagnetic coils. Then, the comprehensive test and evaluation of thermal barrier coating system can be realized. The sensor is optimized by means of theoretical and simulation analysis, and the interaction between the planar capacitor and the electromagnetic coil is studied. The experimental system is built based on an impedance analyser and multiplex unit to evaluate the performance of the composite sensor. The transimpedances and capacitances are measured under different coating parameters, such as thickness and permittivity of top coating as well as bond layer conductivity. The experimental results agree with the simulation analysis, and the feasibility of the sensor is proved. PMID:29783746

Low-cost compact thermal imaging sensors for body temperature measurement

NASA Astrophysics Data System (ADS)

Han, Myung-Soo; Han, Seok Man; Kim, Hyo Jin; Shin, Jae Chul; Ahn, Mi Sook; Kim, Hyung Won; Han, Yong Hee

2013-06-01

This paper presents a 32x32 microbolometer thermal imaging sensor for human body temperature measurement. Waferlevel vacuum packaging technology allows us to get a low cost and compact imaging sensor chip. The microbolometer uses V-W-O film as sensing material and ROIC has been designed 0.35-um CMOS process in UMC. A thermal image of a human face and a hand using f/1 lens convinces that it has a potential of human body temperature for commercial use.

Optical fiber sensor based on a polymer optical fiber macro-bend to study thermal expansion of metals

NASA Astrophysics Data System (ADS)

Pakdeevanich, Paradorn

2018-05-01

Thermal expansion is an important parameter for characterization of metals. As metal is heated, the molecules vibrate more violently and expand in all direction. Investigators have focused to study the thermal strain. However, the amount of expansion is difficult to measure. An attempt has been made to develop an apparatus using optical technique. The principle of this system is the transformation of length changes into changes of light intensity. The purpose of this work is to design and develop an optical fiber sensor based on a macro-bend of a polymer optical fiber. In this system, thermal expansion of metal was converted into the rolling of a needle in which placed beneath a flat bar of metal. Optical fiber sensor was attached to the ended section of a needle. As the crimp tube of the fiber sensor was moved due to thermal expansion of metal, the bend radii of optical fiber sensor was changed. As a sequence, the loss induced by the bending effect was depended on the expansion of metal that changed with temperature. In this study, we utilized optical fiber sensor to monitor and compare the thermal expansion of copper, brass and aluminum. According to our experimental results, the linear response with temperature was reported. The measured values of coefficient of thermal expansion was analyzed to be 0.45, 0.35 and 0.32 a.u./°C for aluminum bar, brass bar and copper bar, respectively. In addition, the effect of the size of the diameter of a needle on the response of bending loss was investigated.

Frost sensor for use in defrost controls for refrigeration

DOEpatents

French, Patrick D.; Butz, James R.; Veatch, Bradley D.; O'Connor, Michael W.

2002-01-01

An apparatus and method for measuring the total thermal resistance to heat flow from the air to the evaporative cooler fins of a refrigeration system. The apparatus is a frost sensor that measures the reduction in heat flow due to the added thermal resistance of ice (reduced conduction) as well as the reduction in heat flow due to the blockage of airflow (reduced convection) from excessive ice formation. The sensor triggers a defrost cycle when needed, instead of on a timed interval. The invention is also a method for control of frost in a system that transfers heat from air to a refrigerant along a thermal path. The method involves measuring the thermal conductivity of the thermal path from the air to the refrigerant, recognizing a reduction in thermal conductivity due to the thermal insulation effect of the frost and due to the loss of airflow from excessive ice formation; and controlling the defrosting of the system.

Li-ion battery thermal runaway suppression system using microchannel coolers and refrigerant injections

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

Bandhauer, Todd M.; Farmer, Joseph C.

A battery management system with thermally integrated fire suppression includes a multiplicity of individual battery cells in a housing; a multiplicity of cooling passages in the housing within or between the multiplicity of individual battery cells; a multiplicity of sensors operably connected to the individual battery cells, the sensors adapted to detect a thermal runaway event related to one or more of the multiplicity of individual battery cells; and a management system adapted to inject coolant into at least one of the multiplicity of cooling passages upon the detection of the thermal runaway event by the any one of themore » multiplicity of sensors, so that the thermal runaway event is rapidly quenched.« less

Sensors, Volume 4, Thermal Sensors

NASA Astrophysics Data System (ADS)

Scholz, Jorg; Ricolfi, Teresio

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 volume describes the construction and applicational aspects of thermal sensors while presenting a rigorous treatment of the underlying physical principles. It provides a unique overview of the various categories of sensors as well as of specific groups, e.g. temperature sensors (resistance thermometers, thermocouples, and radiation thermometers), noise and acoustic thermometers, heat-flow and mass-flow sensors. Specific facettes of applications are presented by specialists from different fields including process control, automotive technology and cryogenics. This volume is an indispensable reference work and text book for both specialists and newcomers, researchers and developers.

Sensitivity improvement of a thermal convection-based tilt sensor using carbon nanotube

NASA Astrophysics Data System (ADS)

Han, Maeum; Kim, Jae-Keon; Bae, Gong-Myeong; Bang, Younghwan; Lee, Gil S.; Kang, Shin-Won; Jung, Daewoong

2017-06-01

This paper presents a thermal convection-based sensor, which is fabricated using carbon nanotube (CNT) yarn. The key element in this device is the non-symmetrically distributed, heated air medium around the heater, particularly when it experiences acceleration and/or changes in inclination. Therefore, it can withstand much higher accelerations/inclination than conventional sensors that use a proof mass. However, a major challenge for the design of this type of sensor is the high heating power (in the order of tens of milliwatts) required to facilitate thermal convection in a sealed chamber. In order to reduce the high heating power, CNTs are investigated as materials for both the heater and the temperature sensors. Moreover, this paper discusses experiments that were performed by varying several parameters, such as the heating power, distance between the heater and temperature sensors, the gas medium used, and air pressure.

Thermal strain measurement of EAST tungsten divertor component with bare fiber Bragg grating sensors

NASA Astrophysics Data System (ADS)

Wang, Xingli; Wang, Wanjing; Wang, Jichao; Wei, Ran; Sun, Zhaoxuan; Li, Qiang; Xie, Chunyi; Luo, Guang-Nan

2017-12-01

Fiber Bragg Gratings (FBGs) have been widely used in the sensor field to monitor temperature and strain. However, the weak mechanical property of optical fibers and insufficient heat-resistant property of general optic-fiber sensors have prevented it from being widely used, such as in some extreme engineering situations. In this work, a bare FBG sensor system had been introduced to measure thermal strain of an Experimental Advanced Superconducting Tokamak tungsten divertor component under baking condition. This strain measurement system had withstood as high temperature as 210 °C and finished the measurement experiment successfully. Meaningful measurement results had been obtained and analyzed, which showed the applicability of such a bare fiber grating sensor system and as well contributed to studying on tungsten divertor's thermal strain conditions.

Achieving thermography with a thermal security camera using uncooled amorphous silicon microbolometer image sensors

NASA Astrophysics Data System (ADS)

Wang, Yu-Wei; Tesdahl, Curtis; Owens, Jim; Dorn, David

2012-06-01

Advancements in uncooled microbolometer technology over the last several years have opened up many commercial applications which had been previously cost prohibitive. Thermal technology is no longer limited to the military and government market segments. One type of thermal sensor with low NETD which is available in the commercial market segment is the uncooled amorphous silicon (α-Si) microbolometer image sensor. Typical thermal security cameras focus on providing the best image quality by auto tonemaping (contrast enhancing) the image, which provides the best contrast depending on the temperature range of the scene. While this may provide enough information to detect objects and activities, there are further benefits of being able to estimate the actual object temperatures in a scene. This thermographic ability can provide functionality beyond typical security cameras by being able to monitor processes. Example applications of thermography[2] with thermal camera include: monitoring electrical circuits, industrial machinery, building thermal leaks, oil/gas pipelines, power substations, etc...[3][5] This paper discusses the methodology of estimating object temperatures by characterizing/calibrating different components inside a thermal camera utilizing an uncooled amorphous silicon microbolometer image sensor. Plots of system performance across camera operating temperatures will be shown.

Fabrication of thermal microphotonic sensors and sensor arrays

DOEpatents

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

2010-10-26

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

Improved Thermal-Vacuum Compatible Flat Plate Radiometric Source For System-Level Testing Of Optical Sensors

NASA Technical Reports Server (NTRS)

Schwarz, Mark A.; Kent, Craig J.; Bousquet, Robert; Brown, Steven W.

2016-01-01

In this work, we describe an improved thermal-vacuum compatible flat plate radiometric source which has been developed and utilized for the characterization and calibration of remote optical sensors. This source is unique in that it can be used in situ, in both ambient and thermal-vacuum environments, allowing it to follow the sensor throughout its testing cycle. The performance of the original flat plate radiometric source was presented at the 2009 SPIE1. Following the original efforts, design upgrades were incorporated into the source to improve both radiometric throughput and uniformity. The pre-thermal-vacuum (pre-TVAC) testing results of a spacecraft-level optical sensor with the improved flat plate illumination source, both in ambient and vacuum environments, are presented. We also briefly discuss potential FPI configuration changes in order to improve its radiometric performance.

Thermal-dissipation sap flow sensors may not yield consistent sap-flux estimates over multiple years

Treesearch

Georgianne W. Moore; Barbara J. Bond; Julia A. Jones; Frederick C. Meinzer

2010-01-01

Sap flow techniques, such as thermal dissipation, involve an empirically derived relationship between sap flux and the temperature differential between a heated thermocouple and a nearby reference thermocouple inserted into the sapwood. This relationship has been widely tested but mostly with newly installed sensors. Increasingly, sensors are used for extended periods...

Damage Detection/Locating System Providing Thermal Protection

NASA Technical Reports Server (NTRS)

Woodard, Stanley E. (Inventor); Jones, Thomas W. (Inventor); Taylor, Bryant D. (Inventor); Qamar, A. Shams (Inventor)

2010-01-01

A damage locating system also provides thermal protection. An array of sensors substantially tiles an area of interest. Each sensor is a reflective-surface conductor having operatively coupled inductance and capacitance. A magnetic field response recorder is provided to interrogate each sensor before and after a damage condition. Changes in response are indicative of damage and a corresponding location thereof.

Controllable synthesis of CuS hollow microflowers hierarchical structures for asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Liu, Yanxia; Zhou, Zhaoxiao; Zhang, Shengping; Luo, Wenhao; Zhang, Guofeng

2018-06-01

One of the major challenges of high-performance asymmetric supercapacitors is engineering electrode materials with high capacitance and good cycling stability. Hence, we have successfully prepared different CuS hierarchical structures including CuS tubular structures (T-CuS), CuS hollow microspheres (S-CuS) and CuS hollow microflowers (H-CuS) by adjusting the solvents, all of which are investigated as electrode materials for supercapacitors. Among them, the H-CuS electrode exhibits the best electrochemical performance involving a high capacitance of 536.7 F g-1 at a current density of 8 A g-1 and excellent cycling stability with 83.6% capacitance retention for 20,000 continuous cycles at a current density of 5 A g-1. In addition, an asymmetric supercapacitor has assembled with H-CuS as positive electrode and activated carbon (AC) as negative electrode, which exhibits a desirable energy density of 15.97 W h kg-1 when the power density is 185.4 W kg-1. These desirable electrochemical performances powerfully demonstrate that the H-CuS electrode has promising potential for applications in energy storage fields.

Preparation and characterization of HA microflowers coating on AZ31 magnesium alloy by micro-arc oxidation and a solution treatment

NASA Astrophysics Data System (ADS)

Tang, Hui; Yu, Dezhen; Luo, Yan; Wang, Fuping

2013-01-01

Magnesium and its alloys are potential biodegradable implant materials due to their attractive biological properties. But the use of magnesium is still hampered by its poor corrosion resistance in physiological fluids. In this work, hydroxyapatite microflowers coating is fabricated by micro-arc oxidation and a solution treatment on AZ31 magnesium alloy. The microstructure and composition are analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The potentiodynamic polarization and electrochemical impedance spectroscopy are studied in simulated body fluid (SBF) solution, and the apatite-forming ability is studied also. The results show that the corrosion resistance of the magnesium alloy has been enhanced by MAO coating. And the solution treatment can improve the corrosion resistance of the MAO sample, by forming a barrier layer on the surface of the MAO coating, and by penetrating into the outer layer of the MAO film, sealing the micropores and micro-cracks existed in the MAO coating. In addition, the MAO-ST coating also exhibits a high ability to form apatite.

Micro-flow photosynthesis of new dienophiles for inverse-electron-demand Diels–Alder reactions. Potential applications for pretargeted in vivo PET imaging† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6sc02933g Click here for additional data file.

PubMed Central

Billaud, Emilie M. F.; Shahbazali, Elnaz; Ahamed, Muneer; Cleeren, Frederik; Noël, Timothy; Koole, Michel; Verbruggen, Alfons; Hessel, Volker

2017-01-01

Pretargeted PET imaging has emerged as an effective two-step in vivo approach that combines the superior affinity and selectivity of antibodies with the rapid pharmacokinetics and favorable dosimetry of smaller molecules radiolabeled with short-lived radionuclides. This approach can be based on the bioorthogonal inverse-electron-demand Diels–Alder (IEDDA) reaction between tetrazines and trans-cyclooctene (TCO) derivatives. We aimed to develop new [18F]TCO–dienophiles with high reactivity for IEDDA reactions, and favorable in vivo stability and pharmacokinetics. New dienophiles were synthesized using an innovative micro-flow photochemistry process, and their reaction kinetics with a tetrazine were determined. In vivo stability and biodistribution of the most promising 18F-radiolabeled-TCO-derivative ([18F]3) was investigated, and its potential for in vivo pretargeted PET imaging was assessed in tumor-bearing mice. We demonstrated that [18F]3 is a suitable dienophile for IEDDA reactions and for pretargeting applications. PMID:28451267

Thermal Testing and Integration: Magnetospheric MultiScale (MMS) Observatories with Digital 1-Wire Sensors

NASA Technical Reports Server (NTRS)

Solimani, Jason A.; Rosanova, Santino

2015-01-01

Thermocouples require two thin wires to be routed out of the spacecraft to connect to the ground support equipment used to monitor and record the temperature data. This large number of wires that exit the observatory complicates integration and creates an undesirable heat path during testing. These wires exiting the spacecraft need to be characterized as a thermal short that will not exist during flight. To minimize complexity and reduce thermal variables from these ground support equipment (GSE) wires, MMS pursued a hybrid path for temperature monitoring, utilizing thermocouples and digital 1-wire temperature sensors. Digital 1-wire sensors can greatly reduce harness mass, length and complexity as they can be spliced together. For MMS, 350 digital 1-wire sensors were installed on the spacecraft with only 18 wires exiting as opposed to a potential 700 thermocouple wires. Digital 1-wire sensors had not been used in such a large scale at NASAGSFC prior to the MMS mission. During the MMS thermal vacuum testing a lessons learned matrix was formulated that will assist future integration of 1-wires into thermal testing and one day into flight.

Sensitive thermal microsensor with pn junction for heat measurement of a single cell

NASA Astrophysics Data System (ADS)

Yamada, Taito; Inomata, Naoki; Ono, Takahito

2016-02-01

A sensitive thermal microsensor based on a pn junction diode for heat measurements of biological single cells is developed and evaluated. Using a fabricated device, we demonstrated the heat measurement of a single brown fat cell. The principle of the sensor relies on the temperature dependence of the pn junction diode resistance. This method has a capability of the highly thermal sensitivity by downsizing and the advantage of a simple experimental setup using electrical circuits without any special equipment. To achieve highly sensitive heat measurement of single cells, downsizing of the sensor is necessary to reduce the heat capacity of the sensor itself. The sensor with the pn junction diode can be downsized by microfabrication. A bridge beam structure with the pn junction diode as a thermal sensor is placed in vacuum using a microfludic chip to decrease the heat loss to the surroundings. A temperature coefficient of resistance of 1.4%/K was achieved. The temperature and thermal resolutions of the fabricated device are 1.1 mK and 73.6 nW, respectively. The heat measurements of norepinephrine stimulated and nonstimulated single brown fat cells were demonstrated, and different behaviors in heat generation were observed.

On the Fracture Toughness and Crack Growth Resistance of Bio-Inspired Thermal Spray Hybrid Composites

NASA Astrophysics Data System (ADS)

Resnick, Michael Murray

Surface exploration of the Moon and Asteroids can provide important information to scientists regarding the origins of the solar-system and life . Small robots and sensor modules can enable low-cost surface exploration. In the near future, they are the main machines providing these answers. Advanced in electronics, sensors and actuators enable ever smaller platforms, with compromising functionality. However similar advances haven't taken place for power supplies and thermal control system. The lunar south pole has temperatures in the range of -100 to -150 °C. Similarly, asteroid surfaces can encounter temperatures of -150 °C. Most electronics and batteries do not work below -40 °C. An effective thermal control system is critical towards making small robots and sensors module for extreme environments feasible. In this work, the feasibility of using thermochemical storage materials as a possible thermal control solution is analyzed for small robots and sensor modules for lunar and asteroid surface environments. The presented technology will focus on using resources that is readily generated as waste product aboard a spacecraft or is available off-world through In-Situ Resource Utilization (ISRU). In this work, a sensor module for extreme environment has been designed and prototyped. Our intention is to have a network of tens or hundreds of sensor modules that can communicate and interact with each other while also gathering science data. The design contains environmental sensors like temperature sensors and IMU (containing accelerometer, gyro and magnetometer) to gather data. The sensor module would nominally contain an electrical heater and insulation. The thermal heating effect provided by this active heater is compared with the proposed technology that utilizes thermochemical storage chemicals. Our results show that a thermochemical storage-based thermal control system is feasible for use in extreme temperatures. A performance increase of 80% is predicted for the sensor modules on the asteroid Eros using thermochemical based storage system. At laboratory level, a performance increase of 8 to 9 % is observed at ambient temperatures of -32°C and -40 °C.

In situ measurement of the junction temperature of light emitting diodes using a flexible micro temperature sensor.

PubMed

Lee, Chi-Yuan; Su, Ay; Liu, Yin-Chieh; Fan, Wei-Yuan; Hsieh, Wei-Jung

2009-01-01

This investigation aimed to fabricate a flexible micro resistive temperature sensor to measure the junction temperature of a light emitting diode (LED). The junction temperature is typically measured using a thermal resistance measurement approach. This approach is limited in that no standard regulates the timing of data capture. This work presents a micro temperature sensor that can measure temperature stably and continuously, and has the advantages of being lightweight and able to monitor junction temperatures in real time. Micro-electro-mechanical-systems (MEMS) technologies are employed to minimize the size of a temperature sensor that is constructed on a stainless steel foil substrate (SS-304 with 30 μm thickness). A flexible micro resistive temperature sensor can be fixed between the LED chip and the frame. The junction temperature of the LED can be measured from the linear relationship between the temperature and the resistance. The sensitivity of the micro temperature sensor is 0.059 ± 0.004 Ω/°C. The temperature of the commercial CREE(®) EZ1000 chip is 119.97 °C when it is thermally stable, as measured using the micro temperature sensor; however, it was 126.9 °C, when measured by thermal resistance measurement. The micro temperature sensor can be used to replace thermal resistance measurement and performs reliably.

A High-Precision Micropipette Sensor for Cellular-Level Real-Time Thermal Characterization

PubMed Central

Shrestha, Ramesh; Choi, Tae-Youl; Chang, Wonseok; Kim, Donsik

2011-01-01

We report herein development of a novel glass micropipette thermal sensor fabricated in a cost-effective manner, which is capable of measuring steady thermal fluctuation at spatial resolution of ∼2 μm with an accuracy of ±0.01 °C. We produced and tested various micrometer-sized sensors, ranging from 2 μm to 30 μm. The sensor comprises unleaded low-melting-point solder alloy (Sn-based) as a core metal inside a pulled borosilicate glass pipette and a thin film of nickel coating outside, creating a thermocouple junction at the tip. The sensor was calibrated using a thermally insulated calibration chamber, the temperature of which can be controlled with an accuracy of ±0.01 °C, and the thermoelectric power (Seebeck coefficient) of the sensor was recorded from 8.46 to 8.86 μV/°C. We have demonstrated the capability of measuring temperatures at a cellular level by inserting our temperature sensor into the membrane of a live retinal pigment epithelium cell subjected to a laser beam with a focal spot of 6 μm. We measured transient temperature profiles and the maximum temperatures were in the range of 38–55 ± 0.5 °C. PMID:22164108

Integration of Microfractionation, qNMR and Zebrafish Screening for the In Vivo Bioassay-Guided Isolation and Quantitative Bioactivity Analysis of Natural Products

PubMed Central

Maes, Jan; Siverio-Mota, Dany; Marcourt, Laurence; Munck, Sebastian; Kamuhabwa, Appolinary R.; Moshi, Mainen J.; Esguerra, Camila V.; de Witte, Peter A. M.; Crawford, Alexander D.; Wolfender, Jean-Luc

2013-01-01

Natural products (NPs) are an attractive source of chemical diversity for small-molecule drug discovery. Several challenges nevertheless persist with respect to NP discovery, including the time and effort required for bioassay-guided isolation of bioactive NPs, and the limited biomedical relevance to date of in vitro bioassays used in this context. With regard to bioassays, zebrafish have recently emerged as an effective model system for chemical biology, allowing in vivo high-content screens that are compatible with microgram amounts of compound. For the deconvolution of the complex extracts into their individual constituents, recent progress has been achieved on several fronts as analytical techniques now enable the rapid microfractionation of extracts, and microflow NMR methods have developed to the point of allowing the identification of microgram amounts of NPs. Here we combine advanced analytical methods with high-content screening in zebrafish to create an integrated platform for microgram-scale, in vivo NP discovery. We use this platform for the bioassay-guided fractionation of an East African medicinal plant, Rhynchosia viscosa, resulting in the identification of both known and novel isoflavone derivatives with anti-angiogenic and anti-inflammatory activity. Quantitative microflow NMR is used both to determine the structure of bioactive compounds and to quantify them for direct dose-response experiments at the microgram scale. The key advantages of this approach are (1) the microgram scale at which both biological and analytical experiments can be performed, (2) the speed and the rationality of the bioassay-guided fractionation – generic for NP extracts of diverse origin – that requires only limited sample-specific optimization and (3) the use of microflow NMR for quantification, enabling the identification and dose-response experiments with only tens of micrograms of each compound. This study demonstrates that a complete in vivo bioassay-guided fractionation can be performed with only 20 mg of NP extract within a few days. PMID:23700445

Recent improvements of the French liquid micro-flow reference facility

NASA Astrophysics Data System (ADS)

Florestan, Ogheard; Sandy, Margot; Julien, Savary

2018-02-01

According to the mission of the national reference laboratory, LNE-CETIAT achieved in 2012 the construction and accreditation of a modern and innovative calibration laboratory based on the gravimetric method. The measurement capabilities cover a flow rate range for liquid from 10 kg · h-1 down to 1 g · h-1 with expanded relative uncertainties from 0.1% to 0.6% (k  =  2). Since 2012, several theoretical and experimental studies have allowed a better knowledge and control over uncertainty sources and have decreased calibration time. When dealing with liquid micro-flow using a reference method such as the gravimetric method, several difficulties have to be overcome. The main improvements described in this paper relate to the enhancement of the evaporation trap system, the merging of the four dedicated measurement lines into one, and the implementation of a gravimetric dynamic ‘flying’ method for the calculation of the reference flow rate. The evaporation-avoiding system has been replaced by an oil layer in order to remove the possibility of condensation of water on both the weighed vessel and the immersed capillary. The article describes the experimental method used to quantify the effect of surface tension of water/oil/air interfaces on the weighed mass. The traditional static gravimetric method has been upgraded by a dynamic ‘flying’ gravimetric method. The article presents the newly implemented method, its validation and its advantages compared to the static method. The four dedicated weighing devices, dispatched over four sub-ranges of flow rate, have been merged leading to the use of only one weighing scale with the same uncertainties on the reference flow rate. The article discusses the new uncertainty budget over the full flow rate range capability. Finally, the article discusses the improvements still under development and the general prospects of liquid micro-flow metrology.

A review of micromachined thermal accelerometers

NASA Astrophysics Data System (ADS)

Mukherjee, Rahul; Basu, Joydeep; Mandal, Pradip; Guha, Prasanta Kumar

2017-12-01

A thermal convection based micro-electromechanical accelerometer is a relatively new kind of acceleration sensor that does not require a solid proof mass, yielding unique benefits like high shock survival rating, low production cost, and integrability with CMOS integrated circuit technology. This article provides a comprehensive survey of the research, development, and current trends in the field of thermal acceleration sensors, with detailed enumeration on the theory, operation, modeling, and numerical simulation of such devices. Different reported varieties and structures of thermal accelerometers have been reviewed highlighting key design, implementation, and performance aspects. Materials and technologies used for fabrication of such sensors have also been discussed. Further, the advantages and challenges for thermal accelerometers vis-à-vis other prominent accelerometer types have been presented, followed by an overview of associated signal conditioning circuitry and potential applications.

Self-diagnostic thermal protection systems for future spacecraft

NASA Astrophysics Data System (ADS)

Hanlon, Alaina B.

The thermal protection system (TPS) represents the greatest risk factor after propulsion for any transatmospheric mission (Dr. Charles Smith, NASA ARC). Any damage to the TPS leaves the space vehicle vulnerable and could result in the loss of human life as happened in the Columbia accident. Aboard the current Space Shuttle Orbiters no system exists to notify the astronauts or ground control if the thermal protection system has been damaged. Through this research, a proof-of-concept monitoring system was developed. The system has two specific applications for thermal protection systems: (1) Improving models used to predict thermal and mechanical response of TPS materials, and (2) Self-diagnosing damage within regions of the TPS and communicating the damage to the appropriate personnel over a potentially unstable network. Mechanical damage is among the most important things to protect the TPS against. Methods to detect the primary types of mechanical damage suffered by thermal protection systems have been developed. Lightweight, low-power sensors were developed to detect any cracks in small regions of a TPS. Implementation of a network of these sensors within 10's to 1000's of regions will eventually provide high spatial resolution of damage detection; allowing for detection of holes in the TPS. Also important in thermal protection material development is to know the ablation rates and time/temperature response of the materials. A new type of sensor has been developed to monitor temperature at different depths within thermal protection materials. The signals being transmitted through the sensors can be multiplexed to allow for mechanical damage and temperature to be monitored using the same sensor.

Fiber Optic Temperature Sensors in TPS: Arc Jet Model Design & Testing

NASA Technical Reports Server (NTRS)

Black, Richard; Feldman, Jay; Ellerby, Donald; Monk, Joshua; Moslehi, Behzad; Oblea, Levy; Switzer, Matthew

2017-01-01

Techniques for using fiber optics with Fiber Bragg Gratings (FBGs) have been developed by IFOS Corp. for use in thermal protection systems (TPS) on spacecraft heat shield materials through NASA Phase 1 and 2 SBIR efforts and have been further improved in a recent collaboration between IFOS and NASA that will be described here. Fiber optic temperature sensors offer several potential advantages over traditional thermocouple sensors including a) multiplexing many sensors in a single fiber to increase sensor density in a given array or to provide spatial resolution, b) improved thermal property match between sensor and TPS to reduce heat flow disruption, c) lack of electrical conductivity.

Spatio-thermal depth correction of RGB-D sensors based on Gaussian processes in real-time

NASA Astrophysics Data System (ADS)

Heindl, Christoph; Pönitz, Thomas; Stübl, Gernot; Pichler, Andreas; Scharinger, Josef

2018-04-01

Commodity RGB-D sensors capture color images along with dense pixel-wise depth information in real-time. Typical RGB-D sensors are provided with a factory calibration and exhibit erratic depth readings due to coarse calibration values, ageing and thermal influence effects. This limits their applicability in computer vision and robotics. We propose a novel method to accurately calibrate depth considering spatial and thermal influences jointly. Our work is based on Gaussian Process Regression in a four dimensional Cartesian and thermal domain. We propose to leverage modern GPUs for dense depth map correction in real-time. For reproducibility we make our dataset and source code publicly available.

Wireless Subsurface Microsensors for Health Monitoring of Thermal Protection Systems on Hypersonic Vehicles

NASA Technical Reports Server (NTRS)

Milos, Frank S.; Watters, David G.; Pallix, Joan B.; Bahr, Alfred J.; Huestis, David L.; Arnold, Jim (Technical Monitor)

2001-01-01

Health diagnostics is an area where major improvements have been identified for potential implementation into the design of new reusable launch vehicles in order to reduce life cycle costs, to increase safety margins, and to improve mission reliability. NASA Ames is leading the effort to develop inspection and health management technologies for thermal protection systems. This paper summarizes a joint project between NASA Ames and SRI International to develop 'SensorTags,' radio frequency identification devices coupled with event-recording sensors, that can be embedded in the thermal protection system to monitor temperature or other quantities of interest. Two prototype SensorTag designs containing thermal fuses to indicate a temperature overlimit are presented and discussed.

Embedded and conventional ultrasonic sensors for monitoring acoustic emission during thermal fatigue

NASA Astrophysics Data System (ADS)

Trujillo, Blaine; Zagrai, Andrei

2016-04-01

Acoustic emission is widely used for monitoring pressure vessels, pipes, critical infrastructure, as well as land, sea and air vehicles. It is one of dominant approaches to explore material degradation under fatigue and events leading to material fracture. Addressing a recent interest in structural health monitoring of space vehicles, a need has emerged to evaluate material deterioration due to thermal fatigue during spacecraft atmospheric reentry. Thermal fatigue experiments were conducted, in which aluminum plates were subjected to localized heating and acoustic emission was monitoring by embedded and conventional acoustic emission sensors positioned at various distances from a heat source. At the same time, surface temperature of aluminum plates was monitored using an IR camera. Acoustic emission counts collected by embedded sensors were compared to counts measured with conventional acoustic emission sensors. Both types of sensors show noticeable increase of acoustic emission activity as localized heating source was applied to aluminum plates. Experimental data demonstrate correlation between temperature increase on the surface of the plates and increase in measured acoustic emission activity. It is concluded that under particular conditions, embedded piezoelectric wafer active sensors can be used for acoustic emission monitoring of thermally-induced structural degradation.

Thermal Balance Analysis of a Micro-Thermoelectric Gas Sensor Using Catalytic Combustion of Hydrogen

PubMed Central

Nagai, Daisuke; Akamatsu, Takafumi; Itoh, Toshio; Izu, Noriya; Shin, Woosuck

2014-01-01

A thermoelectric gas sensor (TGS) with a combustion catalyst is a calorimetric sensor that changes the small heat of catalytic combustion into a signal voltage. We analyzed the thermal balance of a TGS to quantitatively estimate the sensor parameters. The voltage signal of a TGS was simulated, and the heat balance was calculated at two sections across the thermoelectric film of a TGS. The thermal resistances in the two sections were estimated from the thermal time constants of the experimental signal curves of the TGS. The catalytic combustion heat Qcatalyst required for 1 mV of ΔVgas was calculated to be 46.1 μW. Using these parameters, we find from simulations for the device performance that the expected Qcatalyst for 200 and 1,000 ppm H2 was 3.69 μW and 11.7 μW, respectively. PMID:24451468

Thermal Spray Applications in Electronics and Sensors: Past, Present, and Future

NASA Astrophysics Data System (ADS)

Sampath, Sanjay

2010-09-01

Thermal spray has enjoyed unprecedented growth and has emerged as an innovative and multifaceted deposition technology. Thermal spray coatings are crucial to the enhanced utilization of various engineering systems. Industries, in recognition of thermal spray's versatility and economics, have introduced it into manufacturing environments. The majority of modern thermal spray applications are "passive" protective coatings, and they rarely perform an electronic function. The ability to consolidate dissimilar material multilayers without substrate thermal loading has long been considered a virtue for thick-film electronics. However, the complexity of understanding/controlling materials functions especially those resulting from rapid solidification and layered assemblage has stymied expansion into electronics. That situation is changing: enhancements in process/material science are allowing reconsideration for novel electronic/sensor devices. This review critically examines past efforts in terms of materials functionality from a device perspective, along with ongoing/future concepts addressing the aforementioned deficiencies. The analysis points to intriguing future possibilities for thermal spray technology in the world of thick-film sensors.

A numerical analysis of the performance of unpumped SBE 41 sensors at low flushing rates

NASA Astrophysics Data System (ADS)

Alvarez, A.

2018-05-01

The thermal and hydrodynamic response of a Sea-Bird unpumped CTD SBE 41, is numerically modeled to assess the biases occurring at the slow flushing rates typical of glider operations. Based on symmetry considerations, the sensor response is approximated by coupling the incompressible Navier-Stokes and the thermal advection-diffusion equations in two dimensions. Numerical results illustrate three regimes in the thermal response of the SBE 41 sensor, when crossing water layers with different thermal signatures. A linear decay in time of the bulk temperature of the conductivity cell is initially found. This is induced by the transit of the inflow through the conductivity cell in the form of a relatively narrow jet. Water masses with new thermal signatures do not immediately fill the sensor chambers, where the cross-section widens. Thermal equilibrium of these water masses is then achieved, in a second regime, via a cross-flow thermal diffusion between the boundary of the jet and the walls. Consequently, the evolution of the bulk temperature scales with the square root of time. In a third regime, the evolution of the bulk temperature depends on the thermal gradient between the fluid and the coating material. This results on an exponential decay of the bulk temperature with time. A comprehensive analytical model of the time evolution of the bulk temperature inside a cell is proposed based on these results.

Microphotochemistry: 4,4'-Dimethoxybenzophenone mediated photodecarboxylation reactions involving phthalimides

PubMed Central

Shvydkiv, Oksana; Nolan, Kieran

2011-01-01

Summary A series of 4,4'-dimethoxybenzophenone mediated intra- and intermolecular photodecarboxylation reactions involving phthalimides have been examined under microflow conditions. Conversion rates, isolated yields and chemoselectivities were compared to analogous reactions in a batch photoreactor. In all cases investigated, the microreactions gave superior results thus proving the superiority of microphotochemistry over conventional technologies. PMID:21915208

Modeling and experimental study on characterization of micromachined thermal gas inertial sensors.

PubMed

Zhu, Rong; Ding, Henggao; Su, Yan; Yang, Yongjun

2010-01-01

Micromachined thermal gas inertial sensors based on heat convection are novel devices that compared with conventional micromachined inertial sensors offer the advantages of simple structures, easy fabrication, high shock resistance and good reliability by virtue of using a gaseous medium instead of a mechanical proof mass as key moving and sensing elements. This paper presents an analytical modeling for a micromachined thermal gas gyroscope integrated with signal conditioning. A simplified spring-damping model is utilized to characterize the behavior of the sensor. The model relies on the use of the fluid mechanics and heat transfer fundamentals and is validated using experimental data obtained from a test-device and simulation. Furthermore, the nonideal issues of the sensor are addressed from both the theoretical and experimental points of view. The nonlinear behavior demonstrated in experimental measurements is analyzed based on the model. It is concluded that the sources of nonlinearity are mainly attributable to the variable stiffness of the sensor system and the structural asymmetry due to nonideal fabrication.

Investigation of the sensitivity of MIS-sensor to thermal decomposition products of cables insulation

NASA Astrophysics Data System (ADS)

Filipchuk, D. V.; Litvinov, A. V.; Etrekova, M. O.; Nozdrya, D. A.

2017-12-01

Sensitivity of the MIS-sensor to products of thermal decomposition of insulation and jacket of the most common types of cables is investigated. It is shown that hydrogen is evolved under heating the insulation to temperatures not exceeding 250 °C. Registration of the evolved hydrogen by the MIS-sensor can be used for detection of fires at an early stage.

Modeling and Error Analysis of a Superconducting Gravity Gradiometer.

DTIC Science & Technology

1979-08-01

fundamental limit to instrument - -1- sensitivity is the thermal noise of the sensor . For the gradiometer design outlined above, the best sensitivity...Mapoles at Stanford. Chapter IV determines the relation between dynamic range, the sensor Q, and the thermal noise of the cryogenic accelerometer. An...C.1 Accelerometer Optimization (1) Development and optimization of the loaded diaphragm sensor . (2) Determination of the optimal values of the

Strain monitoring of bismaleimide composites using embedded microcavity sensor

NASA Astrophysics Data System (ADS)

Kaur, Amardeep; Anandan, Sudharshan; Yuan, Lei; Watkins, Steve E.; Chandrashekhara, K.; Xiao, Hai; Phan, Nam

2016-03-01

A type of extrinsic Fabry-Perot interferometer (EFPI) fiber optic sensor, i.e., the microcavity strain sensor, is demonstrated for embedded, high-temperature applications. The sensor is fabricated using a femtosecond (fs) laser. The fs-laser-based fabrication makes the sensor thermally stable to sustain operating temperatures as high as 800°C. The sensor has low sensitivity toward the temperature as compared to its response toward the applied strain. The performance of the EFPI sensor is tested in an embedded application. The host material is carbon fiber/bismaleimide (BMI) composite laminate that offer thermally stable characteristics at high ambient temperatures. The sensor exhibits highly linear response toward the temperature and strain. Analytical work done with embedded optical-fiber sensors using the out-of-autoclave BMI laminate was limited until now. The work presented in this paper offers an insight into the strain and temperature interactions of the embedded sensors with the BMI composites.

Thermal Characterization of a Simulated Fission Engine via Distributed Fiber Bragg Gratings

NASA Astrophysics Data System (ADS)

Duncan, Roger G.; Fielder, Robert S.; Seeley, Ryan J.; Kozikowski, Carrie L.; Raum, Matthew T.

2005-02-01

We report the use of distributed fiber Bragg gratings to monitor thermal conditions within a simulated nuclear reactor core located at the Early Flight Fission Test Facility of the NASA Marshall Space Flight Center. Distributed fiber-optic temperature measurements promise to add significant capability and advance the state-of-the-art in high-temperature sensing. For the work reported herein, seven probes were constructed with ten sensors each for a total of 70 sensor locations throughout the core. These discrete temperature sensors were monitored over a nine hour period while the test article was heated to over 700 °C and cooled to ambient through two operational cycles. The sensor density available permits a significantly elevated understanding of thermal effects within the simulated reactor. Fiber-optic sensor performance is shown to compare very favorably with co-located thermocouples where such co-location was feasible.

Performance of an improved thermal neutron activation detector for buried bulk explosives

NASA Astrophysics Data System (ADS)

McFee, J. E.; Faust, A. A.; Andrews, H. R.; Clifford, E. T. H.; Mosquera, C. M.

2013-06-01

First generation thermal neutron activation (TNA) sensors, employing an isotopic source and NaI(Tl) gamma ray detectors, were deployed by Canadian Forces in 2002 as confirmation sensors on multi-sensor landmine detection systems. The second generation TNA detector is being developed with a number of improvements aimed at increasing sensitivity and facilitating ease of operation. Among these are an electronic neutron generator to increase sensitivity for deeper and horizontally displaced explosives; LaBr3(Ce) scintillators, to improve time response and energy resolution; improved thermal and electronic stability; improved sensor head geometry to minimize spatial response nonuniformity; and more robust data processing. The sensor is described, with emphasis on the improvements. Experiments to characterize the performance of the second generation TNA in detecting buried landmines and improvised explosive devices (IEDs) hidden in culverts are described. Performance results, including comparisons between the performance of the first and second generation systems are presented.

Measurement of the thermal expansion of melt-textured YBCO using optical fibre grating sensors

NASA Astrophysics Data System (ADS)

Zeisberger, M.; Latka, I.; Ecke, W.; Habisreuther, T.; Litzkendorf, D.; Gawalek, W.

2005-02-01

In this paper we present measurements of the thermal expansion of melt-textured YBaCuO in the temperature range 30-300 K by means of optical fibre sensors. The sample, which had a size of 38 × 38 × 18 mm3, was prepared by our standard melt-texturing process using SmBaCuO seeds. One fibre containing three Bragg gratings which act as strain sensors was glued to the sample surface with two sensors parallel to the ab-plane and one sensor parallel to the c-axis. The sample was cooled down to a minimum temperature of 30 K in a vacuum chamber using a closed cycle refrigerator. In the temperature range we used, the thermal expansion coefficients are in the range of (3-9) × 10-6 K-1 (ab-direction) and (5-13) × 10-6 K-1 (c-direction).

Fiber-optic thermometry using thermal radiation from Tm end doped SiO{sub 2} fiber sensor

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

Morita, Kentaro; Katsumata, Toru; Komuro, Shuji

2014-04-15

Fiber-optic thermometry based on temperature dependence of thermal radiation from Tm{sup 3+} ions was studied using Tm end doped SiO{sub 2} fiber sensor. Visible light radiation peaks due to f-f transition of Tm{sup 3+} ion were clearly observed at λ = 690 and 790 nm from Tm end doped SiO{sub 2} fibers sensor at the temperature above 600 °C. Thermal radiation peaks are assigned with f-f transition of Tm{sup 3+} ion, {sup 1}D{sub 2}-{sup 3}H{sub 6}, and {sup 1}G{sub 4}-{sup 3}H{sub 6}. Peak intensity of thermal radiation from Tm{sup 3+} ion increases with temperature. Intensity ratio of thermal radiation peaks atmore » λ = 690 nm against that at λ = 790 nm, I{sub 790/690}, is suitable for the temperature measurement above 750 °C. Two-dimensional temperature distribution in a flame is successfully evaluated by Tm end doped SiO{sub 2} fiber sensor.« less

Effects of Thermal Variability on Broadband Seismometers: Controlled Experiments, Observations, and Implications

NASA Astrophysics Data System (ADS)

Doody, C.; Ringler, A. T.; Anthony, R. E.; Wilson, D.; Holland, A. A.; Hutt, C. R.; Sandoval, L. D.

2017-12-01

Although taking steps to isolate seismic instruments from temperature fluctuations is routine practice within the seismological community, the necessary level of thermal stability required in a broadband installation to avoid generating noise is largely unknown. In order to quantify the temperature sensitivity of seismometers over a broad range of frequencies, we artificially induced local temperature changes on three different models of seismometers to empirically measure the effect of thermal variations on seismometer output. We found that temperature changes above 0.002˚C per day show upwards of 10% change in broadband seismometer amplitude when compared to thermally stable reference measurements. We also find that rises in sensor incoherent self-noise increase with temperature variation; these increases in noise can be modeled as 1/f noise (pink noise). While seismometer output changes that correlate with temperature changes are likely correctable, this increase in 1/f noise is unlikely to be easily corrected for. These experimental results are also compared to data from Global Seismographic Network (GSN)-IRIS/USGS network station TUC (Tucson, Arizona) which is well instrumented with temperature sensors, as well as three different broadband sensors, each of which uses a different method of thermal isolation (i.e. Styrofoam box, 1.2m posthole within the pier, and water bricks). We show that isolating sensors with water bricks, as well as posthole and borehole installations, thermally isolate sensors well enough to remove any thermal variability that would affect their output. We find that better seismometer installations which provide thermal stability below 0.002 ˚C per day could help to improve long-period vertical seismic data across the GSN by decreasing temperature-driven 1/f noise.

Development of heat flux sensors for turbine airfoils

NASA Astrophysics Data System (ADS)

Atkinson, William H.; Cyr, Marcia A.; Strange, Richard R.

1985-10-01

The objectives of this program are to develop heat flux sensors suitable for installation in hot section airfoils of advanced aircraft turbine engines and to experimentally verify the operation of these heat flux sensors in a cylinder in a cross flow experiment. Embedded thermocouple and Gardon gauge sensors were developed and fabricated into both blades and vanes. These were then calibrated using a quartz lamp bank heat source and finally subjected to thermal cycle and thermal soak testing. These sensors were also fabricated into cylindrical test pieces and tested in a burner exhaust to verify heat flux measurements produced by these sensors. The results of the cylinder in cross flow tests are given.

Development of heat flux sensors for turbine airfoils

NASA Technical Reports Server (NTRS)

Atkinson, William H.; Cyr, Marcia A.; Strange, Richard R.

1985-01-01

The objectives of this program are to develop heat flux sensors suitable for installation in hot section airfoils of advanced aircraft turbine engines and to experimentally verify the operation of these heat flux sensors in a cylinder in a cross flow experiment. Embedded thermocouple and Gardon gauge sensors were developed and fabricated into both blades and vanes. These were then calibrated using a quartz lamp bank heat source and finally subjected to thermal cycle and thermal soak testing. These sensors were also fabricated into cylindrical test pieces and tested in a burner exhaust to verify heat flux measurements produced by these sensors. The results of the cylinder in cross flow tests are given.

Holt film wall shear instrumentation for boundary layer transition research

NASA Technical Reports Server (NTRS)

Schneider, Steven P.

1994-01-01

Measurements of the performance of hot-film wall-shear sensors were performed to aid development of improved sensors. The effect of film size and substrate properties on the sensor performance was quantified through parametric studies carried out both electronically and in a shock tube. The results show that sensor frequency response increases with decreasing sensor size, while at the same time sensitivity decreases. Substrate effects were also studied, through parametric variation of thermal conductivity and heat capacity. Early studies used complex dual-layer substrates, while later studies were designed for both single-layer and dual-layer substrates. Sensor failures and funding limitations have precluded completion of the substrate thermal-property tests.

Direct Estimation of Power Distribution in Reactors for Nuclear Thermal Space Propulsion

NASA Astrophysics Data System (ADS)

Aldemir, Tunc; Miller, Don W.; Burghelea, Andrei

2004-02-01

A recently proposed constant temperature power sensor (CTPS) has the capability to directly measure the local power deposition rate in nuclear reactor cores proposed for space thermal propulsion. Such a capability reduces the uncertainties in the estimated power peaking factors and hence increases the reliability of the nuclear engine. The CTPS operation is sensitive to the changes in the local thermal conditions. A procedure is described for the automatic on-line calibration of the sensor through estimation of changes in thermal .conditions.

Pyroelectric Energy Scavenging Techniques for Self-Powered Nuclear Reactor Wireless Sensor Networks

DOE PAGES

Hunter, Scott Robert; Lavrik, Nickolay V; Datskos, Panos G; ...

2014-11-01

Recent advances in technologies for harvesting waste thermal energy from ambient environments present an opportunity to implement truly wireless sensor nodes in nuclear power plants. These sensors could continue to operate during extended station blackouts and during periods when operation of the plant s internal power distribution system has been disrupted. The energy required to power the wireless sensors must be generated using energy harvesting techniques from locally available energy sources, and the energy consumption within the sensor circuitry must therefore be low to minimize power and hence the size requirements of the energy harvester. Harvesting electrical energy from thermalmore » energy sources can be achieved using pyroelectric or thermoelectric conversion techniques. Recent modeling and experimental studies have shown that pyroelectric techniques can be cost competitive with thermoelectrics in self powered wireless sensor applications and, using new temperature cycling techniques, has the potential to be several times as efficient as thermoelectrics under comparable operating conditions. The development of a new thermal energy harvester concept, based on temperature cycled pyroelectric thermal-to-electrical energy conversion, is outlined. This paper outlines the modeling of cantilever and pyroelectric structures and single element devices that demonstrate the potential of this technology for the development of high efficiency thermal-to-electrical energy conversion devices.« less

Pyroelectric Energy Scavenging Techniques for Self-Powered Nuclear Reactor Wireless Sensor Networks

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

Hunter, Scott Robert; Lavrik, Nickolay V; Datskos, Panos G

Recent advances in technologies for harvesting waste thermal energy from ambient environments present an opportunity to implement truly wireless sensor nodes in nuclear power plants. These sensors could continue to operate during extended station blackouts and during periods when operation of the plant s internal power distribution system has been disrupted. The energy required to power the wireless sensors must be generated using energy harvesting techniques from locally available energy sources, and the energy consumption within the sensor circuitry must therefore be low to minimize power and hence the size requirements of the energy harvester. Harvesting electrical energy from thermalmore » energy sources can be achieved using pyroelectric or thermoelectric conversion techniques. Recent modeling and experimental studies have shown that pyroelectric techniques can be cost competitive with thermoelectrics in self powered wireless sensor applications and, using new temperature cycling techniques, has the potential to be several times as efficient as thermoelectrics under comparable operating conditions. The development of a new thermal energy harvester concept, based on temperature cycled pyroelectric thermal-to-electrical energy conversion, is outlined. This paper outlines the modeling of cantilever and pyroelectric structures and single element devices that demonstrate the potential of this technology for the development of high efficiency thermal-to-electrical energy conversion devices.« less

Evaluation of risk and benefit in thermal effusivity sensor for monitoring lubrication process in pharmaceutical product manufacturing.

PubMed

Uchiyama, Jumpei; Kato, Yoshiteru; Uemoto, Yoshifumi

2014-08-01

In the process design of tablet manufacturing, understanding and control of the lubrication process is important from various viewpoints. A detailed analysis of thermal effusivity data in the lubrication process was conducted in this study. In addition, we evaluated the risk and benefit in the lubrication process by a detailed investigation. It was found that monitoring of thermal effusivity detected mainly the physical change of bulk density, which was changed by dispersal of the lubricant and the coating powder particle by the lubricant. The monitoring of thermal effusivity was almost the monitoring of bulk density, thermal effusivity could have a high correlation with tablet hardness. Moreover, as thermal effusivity sensor could detect not only the change of the conventional bulk density but also the fractional change of thermal conductivity and thermal capacity, two-phase progress of lubrication process could be revealed. However, each contribution of density, thermal conductivity, or heat capacity to thermal effusivity has the risk of fluctuation by formulation. After carefully considering the change factor with the risk to be changed by formulation, thermal effusivity sensor can be a useful tool for monitoring as process analytical technology, estimating tablet hardness and investigating the detailed mechanism of the lubrication process.

Apparatus for accurately measuring high temperatures

DOEpatents

Smith, D.D.

The present invention is a thermometer used for measuring furnace temperatures in the range of about 1800/sup 0/ to 2700/sup 0/C. The thermometer comprises a broadband multicolor thermal radiation sensor positioned to be in optical alignment with the end of a blackbody sight tube extending into the furnace. A valve-shutter arrangement is positioned between the radiation sensor and the sight tube and a chamber for containing a charge of high pressure gas is positioned between the valve-shutter arrangement and the radiation sensor. A momentary opening of the valve shutter arrangement allows a pulse of the high gas to purge the sight tube of air-borne thermal radiation contaminants which permits the radiation sensor to accurately measure the thermal radiation emanating from the end of the sight tube.

Apparatus for accurately measuring high temperatures

DOEpatents

Smith, Douglas D.

1985-01-01

The present invention is a thermometer used for measuring furnace temperaes in the range of about 1800.degree. to 2700.degree. C. The thermometer comprises a broadband multicolor thermal radiation sensor positioned to be in optical alignment with the end of a blackbody sight tube extending into the furnace. A valve-shutter arrangement is positioned between the radiation sensor and the sight tube and a chamber for containing a charge of high pressure gas is positioned between the valve-shutter arrangement and the radiation sensor. A momentary opening of the valve shutter arrangement allows a pulse of the high gas to purge the sight tube of air-borne thermal radiation contaminants which permits the radiation sensor to accurately measure the thermal radiation emanating from the end of the sight tube.

The Thermal Infrared Sensor onboard NASA's Mars 2020 Mission

NASA Astrophysics Data System (ADS)

Martinez, G.; Perez-Izquierdo, J.; Sebastian, E.; Ramos, M.; Bravo, A.; Mazo, M.; Rodriguez-Manfredi, J. A.

2017-12-01

NASA's Mars 2020 rover mission is scheduled for launch in July/August 2020 and will address key questions about the potential for life on Mars. The Mars Environmental Dynamics Analyzer (MEDA) is one of the seven instruments onboard the rover [1] and has been designed to assess the environmental conditions across the rover traverse. MEDA will extend the current record of in-situ meteorological measurements at the surface [2] to other locations on Mars. The Thermal InfraRed Sensor (TIRS) [3] is one of the six sensors comprising MEDA. TIRS will use three downward-looking channels to measure (1) the surface skin temperature (with high heritage from the Rover Environmental Monitoring Station onboard the Mars Science Laboratory mission [4]), (2) the upwelling thermal infrared radiation from the surface and (3) the reflected solar radiation at the surface, and two upward-looking channels to measure the (4) downwelling thermal infrared radiation at the surface and (5) the atmospheric temperature. In combination with other MEDA's sensors, TIRS will allow the quantification of the surface energy budget [5] and the determination of key geophysical properties of the terrain such as the albedo and thermal inertia with an unprecedented spatial resolution. Here we present a general description of the TIRS, with focus on its scientific requirements and results from field campaigns showing the performance of the different channels. References:[1] Rodríguez-Manfredi, J. A. et al. (2014), MEDA: An environmental and meteorological package for Mars 2020, LPSC, 45, 2837. [2] Martínez, G.M. et al. (2017), The Modern Near-Surface Martian Climate: A Review of In-situ Meteorological Data from Viking to Curiosity, Space Science Reviews, 1-44. [3] Pérez-Izquierdo, J. et al. (2017), The Thermal Infrared Sensor (TIRS) of the Mars Environmental Dynamics Analyzer (MEDA) Instrument onboard Mars 2020, IEEE. [4] Sebastián, E. et al. (2010), The Rover Environmental Monitoring Station Ground Temperature Sensor: A Pyrometer for Measuring Ground Temperature on Mars," Sensors, vol. 10(10), pp. 9211-9231. [5] Martínez, G. M. et al. (2014), Surface energy budget and thermal inertia at Gale Crater: Calculations from ground-based measurements, J.Geophys. Res. Planets, 119.

Phonon Mechanisms for Excess Heat Capacity in Membrane Isolated Superconducting Transition Edge Sensors

NASA Technical Reports Server (NTRS)

Chervenak, James A.

2012-01-01

The mechanics of phonon transport in membrane-isolated superconducting transition edge sensors is discussed. Surveys of the literature on this type of sensor reveal a number of designs with excess heat capacity and a smaller subset that exhibit decoupling of the superconducting film from the underlying dielectric. A simple model is addressed in which the membrane, despite its thermal isolation, fails to fully thermalize to the temperature of the metal film heating it. A population of phonons exists which is emitted by the metal film, partially thermalizes the dielectric and is then reabsorbed in the metal film without escaping from the device structure to the thermal bath. The size of this population and its contribution to the heat capacity are estimated for several device scenarios.

Red blood cell (RBC) suspensions in confined microflows: Pressure-flow relationship.

PubMed

Stauber, Hagit; Waisman, Dan; Korin, Netanel; Sznitman, Josué

2017-10-01

Microfluidic-based assays have become increasingly popular to explore microcirculation in vitro. In these experiments, blood is resuspended to a desired haematocrit level in a buffer solution, where frequent choices for preparing RBC suspensions comprise notably Dextran and physiological buffer. Yet, the rational for selecting one buffer versus another is often ill-defined and lacks detailed quantification, including ensuing changes in RBC flow characteristics. Here, we revisit RBC suspensions in microflows and attempt to quantify systematically some of the differences emanating between buffers. We measure bulk flow rate (Q) of RBC suspensions, using PBS- and Dextran-40, as a function of the applied pressure drop (ΔP) for two hematocrits (∼0% and 23%). Two distinct microfluidic designs of varying dimensions are employed: a straight channel larger than and a network array similar to the size of individual RBCs. Using the resulting pressure-flow curves, we extract the equivalent hydrodynamic resistances and estimate the relative viscosities. These efforts are a first step in rigorously quantifying the influence of the 'background' buffer on RBC flows within microfluidic devices and thereby underline the importance of purposefully selecting buffer suspensions for microfluidic in vitro assays. Copyright © 2017. Published by Elsevier Ltd.

Thermally emissive sensing materials for chemical spectroscopy analysis

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

Poole, Zsolt; Ohodnicki, Paul R.

A sensor using thermally emissive materials for chemical spectroscopy analysis includes an emissive material, wherein the emissive material includes the thermally emissive materials which emit electromagnetic radiation, wherein the electromagnetic radiation is modified due to chemical composition in an environment; and a detector adapted to detect the electromagnetic radiation, wherein the electromagnetic radiation is indicative of the chemical interaction changes and hence chemical composition and/or chemical composition changes of the environment. The emissive material can be utilized with an optical fiber sensor, with the optical fiber sensor operating without the emissive material probed with a light source external to themore » material.« less

Investigation of the Emissivity and Suitability of a Carbon Thin Film for Terahertz Absorbers

DTIC Science & Technology

2016-06-01

Carbonization In order to verify whether the carbon soot coated THz sensor produces sufficient spectral emissivity for IR-based readout, dummy test...ABSTRACT (maximum 200 words) The main goal of this work is to optimize the emissivity of terahertz (THz) thermal sensors by deposition of a carbon thin...film. Previously, these thermal sensors were designed to detect THz radiation utilizing metamaterials in a complicated optical probing scheme. We

Study of an experimental methodology for thermal properties diagnostic of building envelop

NASA Astrophysics Data System (ADS)

Yang, Yingying; Sempy, Alain; Vogt Wu, Tingting; Sommier, Alain; Dumoulin, Jean; Batsale, Jean Christophe

2017-04-01

The building envelope plays a critical role in determining levels of comfort and building efficiency. Its real thermal properties characterization is of major interest to be able to diagnose energy efficiency performance of buildings (new construction and retrofitted existing old building). Research and development on a possible methodology for energy diagnostic of the building envelop is a hot topic and necessary trend. Many kinds of sensors and instruments are used for the studies. The application of infrared (IR) thermography in non-destructive evaluation has been widely employed for qualitative evaluations for building diagnostics; meanwhile, the IR thermography technology also has a large potentiality for the evaluation of the thermal characteristics of the building envelope. Some promising recent research studies have been carried out with such contactless measurement technique. Nevertheless, research efforts are still required for in situ measurements under natural environmental conditions. In order to develop new solutions for non-intrusive evaluation of local thermal performance, enabling quantitative assessment of thermal properties of buildings and materials, experiments were carried out on a multi-layer pratical scale wall fixed on a caisson placed in a climatic chamber. Six halogen lamps (1.5 kW for each lamp) placed in front of objective wall were used to emulate sunny conditions. The radiative heat flux emitted was monitored and modulated with time according to typical weather data set encountered in France. Both steady state and transient regime heat transfer were studied during these experiments. Contact sensors (thermocouples, heat flux meters, Peltier sensors) and non-contact sensors (thermal IR camera, pyranometer) were used to measure the temperatures and heat flux density evolution. It has to be noticed that the Peltier sensors have been tuned and used with a specific processing to set them compliant for heat flux density measurements. The measured data from different sensors were analysed and compared. The emissivity of wall surface and treated sensor surfaces were evaluated by using an IR camera with an adapted post-processing. Then, convective and radiative heat fluxes, at wall level, were estimated. Finally, the wall thermal properties can be calculated by using the measured temperatures and estimated heat fluxes using a dedicated thermal quadrupoles heat transfer model and an inverse method. This study aims at providing some guidelines for the choice of sensors, measurements protocol and adapted inverse model to be tested in real conditions on pilot situ scale. Aknowledgments : The Authors are very grateful to H2020 Built2Spec project for supporting this work.

Statistical sensor fusion analysis of near-IR polarimetric and thermal imagery for the detection of minelike targets

NASA Astrophysics Data System (ADS)

Weisenseel, Robert A.; Karl, William C.; Castanon, David A.; DiMarzio, Charles A.

1999-02-01

We present an analysis of statistical model based data-level fusion for near-IR polarimetric and thermal data, particularly for the detection of mines and mine-like targets. Typical detection-level data fusion methods, approaches that fuse detections from individual sensors rather than fusing at the level of the raw data, do not account rationally for the relative reliability of different sensors, nor the redundancy often inherent in multiple sensors. Representative examples of such detection-level techniques include logical AND/OR operations on detections from individual sensors and majority vote methods. In this work, we exploit a statistical data model for the detection of mines and mine-like targets to compare and fuse multiple sensor channels. Our purpose is to quantify the amount of knowledge that each polarimetric or thermal channel supplies to the detection process. With this information, we can make reasonable decisions about the usefulness of each channel. We can use this information to improve the detection process, or we can use it to reduce the number of required channels.

Calibration and temperature correction of heat dissipation matric potential sensors

USGS Publications Warehouse

Flint, A.L.; Campbell, G.S.; Ellett, K.M.; Calissendorff, C.

2002-01-01

This paper describes how heat dissipation sensors, used to measure soil water matric potential, were analyzed to develop a normalized calibration equation and a temperature correction method. Inference of soil matric potential depends on a correlation between the variable thermal conductance of the sensor's porous ceramic and matric poten-tial. Although this correlation varies among sensors, we demonstrate a normalizing procedure that produces a single calibration relationship. Using sensors from three sources and different calibration methods, the normalized calibration resulted in a mean absolute error of 23% over a matric potential range of -0.01 to -35 MPa. Because the thermal conductivity of variably saturated porous media is temperature dependent, a temperature correction is required for application of heat dissipation sensors in field soils. A temperature correction procedure is outlined that reduces temperature dependent errors by 10 times, which reduces the matric potential measurement errors by more than 30%. The temperature dependence is well described by a thermal conductivity model that allows for the correction of measurements at any temperature to measurements at the calibration temperature.

Nanoscale Ex-Situ Thermal Impulse Sensors for Structural Fire Forensics.

PubMed

Anderson, Benjamin R; Gese, Natalie; Gunawidjaja, Ray; Eilers, Hergen

2017-01-01

We develop nanoscale ex situ thermal impulse (i.e., the temperature and duration of a heating event) sensors for structural fire forensics using a mixture of two lanthanide-doped oxide precursors (precursor Eu:ZrO 2 and precursor Dy:Y 2 O 3 ) that undergo irreversible phase changes when heated. These changes are probed using photoluminescence (PL) spectroscopy with the PL spectra being dependent on the thermal impulse (TI) experienced by the sensors. By correlating the PL spectra to different in-lab TIs, we are able to produce a spectroscopic calibration for our sensors. This calibration allows us to determine an unknown TI of a heating event using only the PL spectrum of the heated TI sensors. In this study, we report on the calibration of these sensors for isothermal heating durations up to 600 s and isothermal temperatures up to 1273 K. Using this calibration, we also demonstrate their ability to determine an unknown TI and demonstrate their functionality when dispersed into paint, which is heated in the presence of drywall.

Quantifying the Influence of Near-Surface Water-Energy Budgets on Soil Thermal Properties Using a Network of Coupled Meteorological and Vadose Zone Instrument Arrays in Indiana, USA

NASA Astrophysics Data System (ADS)

Naylor, S.; Gustin, A. R.; Ellett, K. M.

2012-12-01

Weather stations that collect reliable, sustained meteorological data sets are becoming more widely distributed because of advances in both instrumentation and data server technology. However, sites collecting soil moisture and soil temperature data remain sparse with even fewer locations where complete meteorological data are collected in conjunction with soil data. Thanks to the advent of sensors that collect continuous in-situ thermal properties data for soils, we have gone a step further and incorporated thermal properties measurements as part of hydrologic instrument arrays in central and northern Indiana. The coupled approach provides insights into the variability of soil thermal conductivity and diffusivity attributable to geologic and climatological controls for various hydrogeologic settings. These data are collected to facilitate the optimization of ground-source heat pumps (GSHPs) in the glaciated Midwest by establishing publicly available data that can be used to parameterize system design models. A network of six monitoring sites was developed in Indiana. Sensors that determine thermal conductivity and diffusivity using radial differential temperature measurements around a heating wire were installed at 1.2 meters below ground surface— a typical depth for horizontal GSHP systems. Each site also includes standard meteorological sensors for calculating reference evapotranspiration following the methods by the Food and Agriculture Organization (FAO) of the United Nations. Vadose zone instrumentation includes time domain reflectometry soil-moisture and temperature sensors installed at 0.3-meter depth intervals down to a 1.8-meter depth, in addition to matric potential sensors at 0.15, 0.3, 0.6, and 1.2 meters. Cores collected at 0.3-meter intervals were analyzed in a laboratory for grain size distribution, bulk density, thermal conductivity, and thermal diffusivity. Our work includes developing methods for calibrating thermal properties sensors based on known standards and comparing measurements from transient line heat source devices. Transform equations have been developed to correct in-situ measurements of thermal conductivity and comparing these results with soil moisture data indicates that thermal conductivity can increase by as much as 25 percent during wetting front propagation. Thermal dryout curves have also been modeled based on laboratory conductivity data collected from core samples to verify field measurements, and alternatively, temperature profile data are used to calibrate near-surface temperature gradient models. We compare data collected across various spatial scales to assess the potential for upscaling near-surface thermal regimes based on available soils data. A long-term goal of the monitoring effort is to establish continuous data sets that determine the effect of climate variability on soil thermal properties such that expected ranges in thermal conductivity can be used to determine optimal ground-coupling loop lengths for GSHP systems.

Thermal Error Test and Intelligent Modeling Research on the Spindle of High Speed CNC Machine Tools

NASA Astrophysics Data System (ADS)

Luo, Zhonghui; Peng, Bin; Xiao, Qijun; Bai, Lu

2018-03-01

Thermal error is the main factor affecting the accuracy of precision machining. Through experiments, this paper studies the thermal error test and intelligent modeling for the spindle of vertical high speed CNC machine tools in respect of current research focuses on thermal error of machine tool. Several testing devices for thermal error are designed, of which 7 temperature sensors are used to measure the temperature of machine tool spindle system and 2 displacement sensors are used to detect the thermal error displacement. A thermal error compensation model, which has a good ability in inversion prediction, is established by applying the principal component analysis technology, optimizing the temperature measuring points, extracting the characteristic values closely associated with the thermal error displacement, and using the artificial neural network technology.

Fiber-optic temperature profiling for thermal protection system heat shields

NASA Astrophysics Data System (ADS)

Black, Richard J.; Costa, Joannes M.; Zarnescu, Livia; Hackney, Drew A.; Moslehi, Behzad; Peters, Kara J.

2016-11-01

To achieve better designs for spacecraft heat shields for missions requiring atmospheric aero-capture or entry/reentry, reliable thermal protection system (TPS) sensors are needed. Such sensors will provide both risk reduction and heat-shield mass minimization, which will facilitate more missions and enable increased payloads and returns. This paper discusses TPS thermal measurements provided by a temperature monitoring system involving lightweight, electromagnetic interference-immune, high-temperature resistant fiber Bragg grating (FBG) sensors with a thermal mass near that of TPS materials together with fast FBG sensor interrogation. Such fiber-optic sensing technology is highly sensitive and accurate, as well as suitable for high-volume production. Multiple sensing FBGs can be fabricated as arrays on a single fiber for simplified design and reduced cost. Experimental results are provided to demonstrate the temperature monitoring system using multisensor FBG arrays embedded in a small-size super-light ablator (SLA) coupon which was thermally loaded to temperatures in the vicinity of the SLA charring temperature. In addition, a high-temperature FBG array was fabricated and tested for 1000°C operation, and the temperature dependence considered over the full range (cryogenic to high temperature) for which silica fiber FBGs have been subjected.

MnNi-based spin valve sensors combining high thermal stability, small footprint and pTesla detectivities

NASA Astrophysics Data System (ADS)

Silva, Marília; Leitao, Diana C.; Cardoso, Susana; Freitas, Paulo

2018-05-01

Magnetoresistive sensors with high thermal robustness, low noise and high spatial resolution are the answer to a number of challenging applications. Spin valve sensors including MnNi as antiferromagnet layer provide higher exchange bias field and improved thermal stability. In this work, the influence of the buffer layer type (Ta, NiFeCr) and thickness on key sensor parameters (e.g. offset field, Hf) is investigated. A Ta buffer layer promotes a strong (111) texture which leads to a higher value of MR. In contrast, Hf is lower for NiFeCr buffer. Micrometric sensors display thermal noise levels of 1 nT/Hz1/2 and 571 pT/Hz1/2 for a sensor height (h) of 2 and 4 μm, respectively. The temperature dependence of MR and sensitivity is also addressed and compared with MnIr based spin valves. In this case, MR abruptly decreases after heating at 160°C (without magnetic field), contrary to MnNi-based spin valves, where only a 10% MR decrease (relative to the initial value) is seen at 275°C. Finally, to further decrease the noise levels and improve detectivity, MnNi spin-valves are deposited vertically, and connected in parallel and series (in-plane) to create a device with low resistance and high sensitivity. A field detection at thermal level of 346 pT/Hz1/2 is achieved for a device with a total of 300 SVs (4 vertical, 15 in series, 5 in parallel).

TPS In-Flight Health Monitoring Project Progress Report

NASA Technical Reports Server (NTRS)

Kostyk, Chris; Richards, Lance; Hudston, Larry; Prosser, William

2007-01-01

Progress in the development of new thermal protection systems (TPS) is reported. New approaches use embedded lightweight, sensitive, fiber optic strain and temperature sensors within the TPS. Goals of the program are to develop and demonstrate a prototype TPS health monitoring system, develop a thermal-based damage detection algorithm, characterize limits of sensor/system performance, and develop ea methodology transferable to new designs of TPS health monitoring systems. Tasks completed during the project helped establish confidence in understanding of both test setup and the model and validated system/sensor performance in a simple TPS structure. Other progress included complete initial system testing, commencement of the algorithm development effort, generation of a damaged thermal response characteristics database, initial development of a test plan for integration testing of proven FBG sensors in simple TPS structure, and development of partnerships to apply the technology.

Thermal infrared sensors for postharvest deficit irrigation of peach

USDA-ARS?s Scientific Manuscript database

California has been in a historic drought and the lack of water has been a major problem for agriculture especially for crops that depend on irrigation. A multi-year field study was carried out to demonstrate the feasibility of applying thermal infrared sensors for managing deficit irrigation in an ...

A screen-printed flexible flow sensor

NASA Astrophysics Data System (ADS)

Moschos, A.; Syrovy, T.; Syrova, L.; Kaltsas, G.

2017-04-01

A thermal flow sensor was printed on a flexible plastic substrate using exclusively screen-printing techniques. The presented device was implemented with custom made screen-printed thermistors, which allows simple, cost-efficient production on a variety of flexible substrates while maintaining the typical advantages of thermal flow sensors. Evaluation was performed for both static (zero flow) and dynamic conditions using a combination of electrical measurements and IR imaging techniques in order to determine important characteristics, such as temperature response, output repeatability, etc. The flow sensor was characterized utilizing the hot-wire and calorimetric principles of operation, while the preliminary results appear to be very promising, since the sensor was successfully evaluated and displayed adequate sensitivity in a relatively wide flow range.

Thermal-Performance Instability in Piezoresistive Sensors: Inducement and Improvement

PubMed Central

Liu, Yan; Wang, Hai; Zhao, Wei; Qin, Hongbo; Fang, Xuan

2016-01-01

The field of piezoresistive sensors has been undergoing a significant revolution in terms of design methodology, material technology and micromachining process. However, the temperature dependence of sensor characteristics remains a hurdle to cross. This review focuses on the issues in thermal-performance instability of piezoresistive sensors. Based on the operation fundamental, inducements to the instability are investigated in detail and correspondingly available ameliorative methods are presented. Pros and cons of each improvement approach are also summarized. Though several schemes have been proposed and put into reality with favorable achievements, the schemes featuring simple implementation and excellent compatibility with existing techniques are still emergently demanded to construct a piezoresistive sensor with excellent comprehensive performance. PMID:27886125

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.

Beam profile measurement on HITU transducers using a thermal intensity sensor technique

NASA Astrophysics Data System (ADS)

Wilkens, V.; Sonntag, S.; Jenderka, K.-V.

2011-02-01

Thermal intensity sensors based on the transformation of the incident ultrasonic energy into heat inside a small cylindrical absorber have been developed at PTB in the past, in particular to determine the acoustic output of medical diagnostic ultrasound equipment. Currently, this sensor technique is being expanded to match the measurement challenges of high intensity therapeutic ultrasound (HITU) fields. At the high acoustic power levels as utilized in the clinical application of HITU transducers, beam characterization using hydrophones is critical due to the possible damage of the sensitive and expensive measurement devices. Therefore, the low-cost and robust thermal sensors developed offer a promising alternative for the determination of high intensity output beam profiles. A sensor prototype with a spatial resolution of 0.5 mm was applied to the beam characterization of an HITU transducer operated at several driving amplitude levels. Axial beam plots and lateral profiles at focus were acquired. The absolute continuous wave output power was, in addition, determined using a radiation force balance.

Spectral Analysis of the Primary Flight Focal Plane Arrays for the Thermal Infrared Sensor

NASA Technical Reports Server (NTRS)

Montanaro, Matthew; Reuter, Dennis C.; Markham, Brian L.; Thome, Kurtis J.; Lunsford, Allen W.; Jhabvala, Murzy D.; Rohrbach, Scott O.; Gerace, Aaron D.

2011-01-01

Thermal Infrared Sensor (TIRS) is a (1) New longwave infrared (10 - 12 micron) sensor for the Landsat Data Continuity Mission, (2) 185 km ground swath; 100 meter pixel size on ground, (3) Pushbroom sensor configuration. Issue of Calibration are: (1) Single detector -- only one calibration, (2) Multiple detectors - unique calibration for each detector -- leads to pixel-to-pixel artifacts. Objectives are: (1) Predict extent of residual striping when viewing a uniform blackbody target through various atmospheres, (2) Determine how different spectral shapes affect the derived surface temperature in a realistic synthetic scene.

Analysis, testing, and operation of the MAGI thermal control system

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

Yi, Sonny; Hall, Jeffrey L.; Kasper, Brian P.

2014-01-29

The Aerospace Corporation has completed the development of the Mineral and Gas Identifier (MAGI) sensor - an airborne multi-spectral infrared instrument that is designed to discriminate surface composition and to detect gas emissions from the environment. Sensor performance was demonstrated in a series of flights aboard a Twin Otter aircraft in December 2011 as a stepping stone to a future satellite sensor design. To meet sensor performance requirements the thermal control system was designed to operate the HgCdTe focal plane array (FPA) at 50 K with a 1.79 W heat rejection load to a 44.7 K sink and the opticalmore » assembly at 100 K with a 7.5 W heat load to a 82.3 K sink. Two commercial off-theshelf (COTS) Sunpower Stirling cryocoolers were used to meet the instrument’s cooling requirements. A thermal model constructed in Thermal Desktop was used to run parametric studies that guided the mechanical design and sized the two cryocoolers. This paper discusses the development, validation, and operation of the MAGI thermal control system. Detailed energy balances and temperature predictions are presented for various test cases to demonstrate the utility and accuracy of the thermal model. Model inputs included measured values of heat lift as a function of input power and cold tip temperature for the two cryocoolers. These measurements were also used to make predictions of the cool-down behavior from ambient conditions. Advanced heater software was developed to meet unique requirements for both sensor cool-down rate and stability at the set point temperatures.« less

All-optical technique for measuring thermal properties of materials at static high pressure

NASA Astrophysics Data System (ADS)

Pangilinan, G. I.; Ladouceur, H. D.; Russell, T. P.

2000-10-01

The development and implementation of an all-optical technique for measuring thermal transport properties of materials at high pressure in a gem anvil cell are reported. Thermal transport properties are determined by propagating a thermal wave in a material subjected to high pressures, and measuring the temperature as a function of time using an optical sensor embedded downstream in the material. Optical beams are used to deposit energy and to measure the sensor temperature and replace the resistive heat source and the thermocouples of previous methods. This overcomes the problems introduced with pressure-induced resistance changes and the spatial limitations inherent in previous high-pressure experimentation. Consistent with the heat conduction equation, the material's specific heat, thermal conductivity, and thermal diffusivity (κ) determine the sensor's temperature rise and its temporal profile. The all-optical technique described focuses on room-temperature thermal properties but can easily be applied to a wide temperature range (77-600 K). Measurements of thermal transport properties at pressure up to 2.0 GPa are reported, although extension to much higher pressures are feasible. The thermal properties of NaCl, a commonly used material for high-pressure experiments are measured and shown to be consistent with those obtained using the traditional methods.

Low cost infrared and near infrared sensors for UAVs

NASA Astrophysics Data System (ADS)

Aden, S. T.; Bialas, J. P.; Champion, Z.; Levin, E.; McCarty, J. L.

2014-11-01

Thermal remote sensing has a wide range of applications, though the extent of its use is inhibited by cost. Robotic and computer components are now widely available to consumers on a scale that makes thermal data a readily accessible resource. In this project, thermal imagery collected via a lightweight remote sensing Unmanned Aerial Vehicle (UAV) was used to create a surface temperature map for the purpose of providing wildland firefighting crews with a cost-effective and time-saving resource. The UAV system proved to be flexible, allowing for customized sensor packages to be designed that could include visible or infrared cameras, GPS, temperature sensors, and rangefinders, in addition to many data management options. Altogether, such a UAV system could be used to rapidly collect thermal and aerial data, with a geographic accuracy of less than one meter.

Active Wireless Temperature Sensors for Aerospace Thermal Protection Systems

NASA Technical Reports Server (NTRS)

Milos, Frank S.; Karunaratne, K.; Arnold, Jim (Technical Monitor)

2002-01-01

Health diagnostics is an area where major improvements have been identified for potential implementation into the design of new reusable launch vehicles in order to reduce life-cycle costs, to increase safety margins, and to improve mission reliability. NASA Ames is leading the effort to advance inspection and health management technologies for thermal protection systems. This paper summarizes a joint project between NASA Ames and Korteks to develop active wireless sensors that can be embedded in the thermal protection system to monitor sub-surface temperature histories. These devices are thermocouples integrated with radio-frequency identification circuitry to enable acquisition and non-contact communication of temperature data through aerospace thermal protection materials. Two generations of prototype sensors are discussed. The advanced prototype collects data from three type-k thermocouples attached to a 2.54-cm square integrated circuit.

Unmanned Aerial System (UAS)-based phenotyping of soybean using multi-sensor data fusion and extreme learning machine

NASA Astrophysics Data System (ADS)

Maimaitijiang, Maitiniyazi; Ghulam, Abduwasit; Sidike, Paheding; Hartling, Sean; Maimaitiyiming, Matthew; Peterson, Kyle; Shavers, Ethan; Fishman, Jack; Peterson, Jim; Kadam, Suhas; Burken, Joel; Fritschi, Felix

2017-12-01

Estimating crop biophysical and biochemical parameters with high accuracy at low-cost is imperative for high-throughput phenotyping in precision agriculture. Although fusion of data from multiple sensors is a common application in remote sensing, less is known on the contribution of low-cost RGB, multispectral and thermal sensors to rapid crop phenotyping. This is due to the fact that (1) simultaneous collection of multi-sensor data using satellites are rare and (2) multi-sensor data collected during a single flight have not been accessible until recent developments in Unmanned Aerial Systems (UASs) and UAS-friendly sensors that allow efficient information fusion. The objective of this study was to evaluate the power of high spatial resolution RGB, multispectral and thermal data fusion to estimate soybean (Glycine max) biochemical parameters including chlorophyll content and nitrogen concentration, and biophysical parameters including Leaf Area Index (LAI), above ground fresh and dry biomass. Multiple low-cost sensors integrated on UASs were used to collect RGB, multispectral, and thermal images throughout the growing season at a site established near Columbia, Missouri, USA. From these images, vegetation indices were extracted, a Crop Surface Model (CSM) was advanced, and a model to extract the vegetation fraction was developed. Then, spectral indices/features were combined to model and predict crop biophysical and biochemical parameters using Partial Least Squares Regression (PLSR), Support Vector Regression (SVR), and Extreme Learning Machine based Regression (ELR) techniques. Results showed that: (1) For biochemical variable estimation, multispectral and thermal data fusion provided the best estimate for nitrogen concentration and chlorophyll (Chl) a content (RMSE of 9.9% and 17.1%, respectively) and RGB color information based indices and multispectral data fusion exhibited the largest RMSE 22.6%; the highest accuracy for Chl a + b content estimation was obtained by fusion of information from all three sensors with an RMSE of 11.6%. (2) Among the plant biophysical variables, LAI was best predicted by RGB and thermal data fusion while multispectral and thermal data fusion was found to be best for biomass estimation. (3) For estimation of the above mentioned plant traits of soybean from multi-sensor data fusion, ELR yields promising results compared to PLSR and SVR in this study. This research indicates that fusion of low-cost multiple sensor data within a machine learning framework can provide relatively accurate estimation of plant traits and provide valuable insight for high spatial precision in agriculture and plant stress assessment.

General characteristics and availability of Landsat 3 and heat capacity mapping mission thermal infrared data

USGS Publications Warehouse

Southworth, C. Scott

1983-01-01

Two satellite systems launched by the National Aeronautics and Space Administration (NASA) in 1978 carried sensors which operated in the thermal infrared (IR) region of the electromagnetic spectrum, The final IR radiation data provide spectral information about the physical properties of the Earth's surficial materials not duplicated in either the visible or reflective IR wavelength regions. Landsat 3, launched on March 5, 1978, contained a thermal sensor as part of the multispectral scanner (MSS) system. The sensor operated in the 10.4- to 12.6-?m (band 8) wavelength region and produced imagery with a ground resolution of approximately 235 m. Launched on April 26) 1978) the Heat Capacity Mapping Mission (HCMM) spacecraft carried a sensor, the heat capacity mapping radiometer (HCMR) which operated in the 10.5- to 12.5?m wavelength region and produced imagery with a ground resolution of approximately 600 m at nadir. The HCMM satellite acquired over 6,600 data passes of visible (0.55-1.1 ?m), as well as thermal IR data, over North America, Europe, and Australia. General characteristics and availability of Landsat 3 and HCMM thermal IR data are discussed. Landsat 3 reflected IR band 7 (0.55-1.1 ?m) and Landsat 3 band 8 thermal data acquired over the eastern and western United States are analyzed and compared with HCMM visible, thermal IR, thermal inertia, and day-night temperature difference imagery for geologic applications. Digitally processed and enhanced HCMM data (high-pass filters, diagonal derivatives, and band ratios), produced by the U.S. Geological Survey, Flagstaff) Ariz., are presented for geologic interpretation.

Analysis of clinical data to determine the minimum number of sensors required for adequate skin temperature monitoring of superficial hyperthermia treatments.

PubMed

Bakker, Akke; Holman, Rebecca; Rodrigues, Dario B; Dobšíček Trefná, Hana; Stauffer, Paul R; van Tienhoven, Geertjan; Rasch, Coen R N; Crezee, Hans

2018-04-27

Tumor response and treatment toxicity are related to minimum and maximum tissue temperatures during hyperthermia, respectively. Using a large set of clinical data, we analyzed the number of sensors required to adequately monitor skin temperature during superficial hyperthermia treatment of breast cancer patients. Hyperthermia treatments monitored with >60 stationary temperature sensors were selected from a database of patients with recurrent breast cancer treated with re-irradiation (23 × 2 Gy) and hyperthermia using single 434 MHz applicators (effective field size 351-396 cm 2 ). Reduced temperature monitoring schemes involved randomly selected subsets of stationary skin sensors, and another subset simulating continuous thermal mapping of the skin. Temperature differences (ΔT) between subsets and complete sets of sensors were evaluated in terms of overall minimum (T min ) and maximum (T max ) temperature, as well as T90 and T10. Eighty patients were included yielding a total of 400 hyperthermia sessions. Median ΔT was <0.01 °C for T90, its 95% confidence interval (95%CI) decreased to ≤0.5 °C when >50 sensors were used. Subsets of <10 sensors result in underestimation of T max up to -2.1 °C (ΔT 95%CI), which decreased to -0.5 °C when >50 sensors were used. Thermal profiles (8-21 probes) yielded a median ΔT < 0.01 °C for T90 and T max , with a 95%CI of -0.2 °C and 0.4 °C, respectively. The detection rate of T max  ≥43 °C is ≥85% while using >50 stationary sensors or thermal profiles. Adequate coverage of the skin temperature distribution during superficial hyperthermia treatment requires the use of >50 stationary sensors per 400 cm 2 applicator. Thermal mapping is a valid alternative.

Development of fiber optic sensing interrogators for launchers

NASA Astrophysics Data System (ADS)

Plattner, M. P.; Buck, T. C.; Eder, B.; Reutlinger, A.; McKenzie, I.

2017-11-01

We present our work about the development of two complementary interrogation schemes based on fiber optic sensing for the use of structural and thermal monitoring of Ariane launchers. The advantages of fiber optic sensing in particular light-weight, immunity to electromagnetic interferences and the possibility of sensor distribution along optical fibers are driving factors for utilization of this technology in space crafts [1]. The edge-filter (EF) and scanning-laser (SL) interrogators for determination of the mean wavelength of fiber Bragg grating (FBG) sensors have been implemented as two separate demonstrators. Within this paper we describe the functional principles of both interrogators. Furthermore we present test results where the developed systems have been used for readout of FBG sensors which are implemented in an Ariane structural demonstrator during thermal, thermal-vacuum and vibration tests. Functionality of both systems is demonstrated and their potential for further development towards space qualified systems is shown. Since the performance characteristics of the two systems are different from each other, they are dedicated for different sensing applications on a launcher. The EF sensor interrogator provides a sample rate of 20 kHz at a number of 4 connected sensors and supports parallel readout and aliasing free operation. Therefore it is best suited for high priority measurement. Structural monitoring which requires the acquisition of real time sensor information in order to support control of the launcher is one operation area for a future EF system. The SL interrogator provides an overall measurement rate of 1 kHz at a number of 24 connected sensors distributed on three sensor channels. It can be adapted to any sensors that have design wavelengths lying within the output spectrum of the laser diode. Furthermore the number of overall sensors to be read out with this system can be adapted easily. Thermal mapping of satellite panels is one possible future application for the SL interrogator.

Characterization of measurement artefacts in fluoroptic temperature sensors: implications for laser thermal therapy at 810 nm.

PubMed

Davidson, Sean R H; Vitkin, I Alex; Sherar, Michael D; Whelan, William M

2005-04-01

Fluoroptic sensors are used to measure interstitial temperatures but their utility for monitoring laser interstitial thermal therapy (LITT) is unclear because these sensors exhibit a measurement artefact when exposed to the near-infrared (NIR) treatment light. This study investigates the cause of the artefact to determine whether fluoroptic sensors can provide reliable temperature measurements during LITT. The temperature rise measured by a fluoroptic sensor irradiated in non-absorbing media (air and water) was considered an artefact. Temperature rise was measured as a function of distance from a laser source. Two different sensor designs and several laser powers were investigated. A relationship between fluence rate and measurement artefact in water was determined and coupled with a numerical simulation of LITT in liver to estimate the error in temperature measurements made by fluoroptic sensors in tissue in proximity to the laser source. The effect of ambient light on the performance of sensors capped with a transparent material ("clear-capped sensors") was also investigated. The temperature rise recorded in air by both clear- and black-capped fluoroptic sensors decreased with distance from a laser source in a manner similar to fluence rate. Sensor cap material, laser power, and the thermal properties of the surrounding medium affected the magnitude of the artefact. Numerical simulations indicated that the accuracy of a clear-capped fluoroptic sensor used to monitor a typical LITT treatment in liver is > 1 degrees C provided the sensor is further than approximately 3 mm from the source. It was also shown that clear-capped fluoroptic sensors are affected by ambient light. The measurement artefact experienced by both black-capped and clear-capped fluoroptic sensors irradiated by NIR light scales with fluence rate and is due to direct absorption of the laser light, which results in sensor self-heating. Clear-capped fluoroptic sensors can be used to accurately monitor LITT in tissue but should be shielded from ambient light. Copyright 2005 Wiley-Liss, Inc.

Retrieving Land Surface Temperature and Emissivity from Multispectral and Hyperspectral Thermal Infrared Instruments

NASA Astrophysics Data System (ADS)

Hook, Simon; Hulley, Glynn; Nicholson, Kerry

2017-04-01

Land Surface Temperature and Emissivity (LST&E) data are critical variables for studying a variety of Earth surface processes and surface-atmosphere interactions such as evapotranspiration, surface energy balance and water vapor retrievals. LST&E have been identified as an important Earth System Data Record (ESDR) by NASA and many other international organizations Accurate knowledge of the LST&E is a key requirement for many energy balance models to estimate important surface biophysical variables such as evapotranspiration and plant-available soil moisture. LST&E products are currently generated from sensors in low earth orbit (LEO) such as the NASA Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on the Terra and Aqua satellites as well as from sensors in geostationary Earth orbit (GEO) such as the Geostationary Operational Environmental Satellites (GOES) and airborne sensors such as the Hyperspectral Thermal Emission Spectrometer (HyTES). LST&E products are generated with varying accuracies depending on the input data, including ancillary data such as atmospheric water vapor, as well as algorithmic approaches. NASA has identified the need to develop long-term, consistent, and calibrated data and products that are valid across multiple missions and satellite sensors. We will discuss the different approaches that can be used to retrieve surface temperature and emissivity from multispectral and hyperspectral thermal infrared sensors using examples from a variety of different sensors such as those mentioned, and planned new sensors like the ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) and the Hyperspectral Infrared Imager (HyspIRI). We will also discuss a project underway at NASA to develop a single unified product from some the individual sensor products and assess the errors associated with the product.

LASER BIOLOGY AND MEDICINE: Recording of lymph flow dynamics in microvessels using correlation properties of scattered coherent radiation

NASA Astrophysics Data System (ADS)

Fedosov, I. V.; Tuchin, Valerii V.; Galanzha, E. I.; Solov'eva, A. V.; Stepanova, T. V.

2002-11-01

The direction-sensitive method of microflow velocity measurements based on the space — time correlation properties of the dynamic speckle field is described and used for in vivo monitoring of lymph flow in the vessels of rat mesentery. The results of measurements are compared with the data obtained from functional video microscopy of the microvessel region.

Calcium Chloride in Neonatal Parenteral Nutrition Solutions with and without Added Cysteine: Compatibility Studies Using Laser and Micro-Flow Imaging Methodology.

PubMed

Huston, Robert K; Christensen, J Mark; Alshahrani, Sultan M; Mohamed, Sumeia M; Clark, Sara M; Nason, Jeffrey A; Wu, Ying Xing

2015-01-01

Previous studies of compatibility of calcium chloride (CaCl2) and phosphates have not included particle counts in the range specified by the United States Pharmacopeia. Micro-flow imaging techniques have been shown to be comparable to light obscuration when determining particle count and size in pharmaceutical solutions. The purpose of this study was to do compatibility testing for parenteral nutrition (PN) solutions containing CaCl2 using dynamic light scattering and micro-flow imaging techniques. Solutions containing TrophAmine (Braun Medical Inc, Irvine, CA), CaCl2, and sodium phosphate (NaPhos) were compounded with and without cysteine. All solutions contained standard additives to neonatal PN solutions including dextrose, trace metals, and electrolytes. Control solutions contained no calcium or phosphate. Solutions were analyzed for particle size and particle count. Means of Z-average particle size and particle counts of controls were determined. Study solutions were compared to controls and United States Pharmacopeia (USP) Chapter 788 guidelines. The maximum amount of Phos that was compatible in solutions that contained at least 10 mmol/L of Ca in 2.5% amino acids (AA) was determined. Compatibility of these solutions was verified by performing analyses of 5 repeats of these solutions. Microscopic analyses of the repeats were also performed. Amounts of CaCl2 and NaPhos that were compatible in solutions containing 1.5%, 2%, 2.5%, and 3% AA were determined. The maximum amount of NaPhos that could be added to TrophAmine solutions of > = 2.5% AA containing at least 10 mmol/L of CaCl2 was 7.5 mmol/L. Adding 50 mg/dL of cysteine increased the amount of NaPhos that could be added to solutions containing 10 mmol/L of CaCl2 to 10 mmol/L. Calcium chloride can be added to neonatal PN solutions containing NaPhos in concentrations that can potentially provide an intravenous intake of adequate amounts of calcium and phosphorus.

The mechanism performance of improved oil pump with micro-structured vanes

NASA Astrophysics Data System (ADS)

Li, Ping; Xie, Jin; Qi, Dongtao; Li, Houbu

2017-09-01

The wear of oil pump vanes easily leads to the noise and vibration, even results the decrease of volume efficiency and total efficiency. In order to reduce the friction and improve the lubrication between the vane and the pump inner wall, the micro-machining of micro-structure on the oil pump vanes is proposed. First, the micro-V-grooves with the depth ranging from 500μm to 50μm were micro-grinding on the top of the vanes by a diamond grinding wheel. Secondly, the experiments were conducted to test the actual flow rate, the output power and the overall efficiency of the oil pump with and without the micro-groove vanes. Then, the computational fluid dynamics (CFD) method was adopted to simulate the pump internal flow field. Finally, the micro-flow field between the internal wall of the oil pump and the top of micro-grooved vanes was analyzed. The results shows that the pump overall efficiency increased as the decrease of micro-groove depth from 500 μm to 50μm and not be affected by the rotate speed and working frequency of the pump rotator. Especially the micro-groove with depth of 50μm, the actual flow rate, the output power and the overall efficiency reached to the maximum. From CFD simulation, the velocity of the micro-flow between the surfaces of the vane and inner wall was larger than the pump linear velocity when the microstructure depth is larger than 50μm, leading to an internal leakage. When the micro-groove depth is between10-50μm, the velocity of the micro-flow was less than the pump linear velocity and no internal leakage was found, but the oil film thickness is too small to be beneficial to lubrication according to the fluid dynamic characteristics. Thus, for the oil pump equipping with micro-grooved vane with the depth of 50 μm, the internal leakage not only is avoided but the lubrication efficiency is improved and the oil pump efficiency is also enhanced.

A Waveguide-coupled Thermally-isolated Radiometric Source

NASA Technical Reports Server (NTRS)

Rostem, Karwan; Chuss, David T.; Lourie, Nathan P.; Voellmer, George M.; Wollack, Edward

2013-01-01

The design and validation of a dual polarization source for waveguide-coupled millimeter and sub-millimeter wave cryogenic sensors is presented. The thermal source is a waveguide mounted absorbing conical dielectric taper. The absorber is thermally isolated with a kinematic suspension that allows the guide to be heat sunk to the lowest bath temperature of the cryogenic system. This approach enables the thermal emission from the metallic waveguide walls to be subdominant to that from the source. The use of low thermal conductivity Kevlar threads for the kinematic mount effectively decouples the absorber from the sensor cold stage. Hence, the absorber can be heated to significantly higher temperatures than the sensor with negligible conductive loading. The kinematic suspension provides high mechanical repeatability and reliability with thermal cycling. A 33-50 GHz blackbody source demonstrates an emissivity of 0.999 over the full waveguide band where the dominant deviation from unity arises from the waveguide ohmic loss. The observed thermal time constant of the source is 40 s when the absorber temperature is 15 K. The specific heat of the lossy dielectric MF-117 is well approximated by Cv(T) = 0.12 T(exp 2.06) mJ/g/K between 3.5 K and 15 K.

Thermal Transport Model for Heat Sink Design

NASA Technical Reports Server (NTRS)

Chervenak, James A.; Kelley, Richard L.; Brown, Ari D.; Smith, Stephen J.; Kilbourne, Caroline a.

2009-01-01

A document discusses the development of a finite element model for describing thermal transport through microcalorimeter arrays in order to assist in heat-sinking design. A fabricated multi-absorber transition edge sensor (PoST) was designed in order to reduce device wiring density by a factor of four. The finite element model consists of breaking the microcalorimeter array into separate elements, including the transition edge sensor (TES) and the silicon substrate on which the sensor is deposited. Each element is then broken up into subelements, whose surface area subtends 10 10 microns. The heat capacity per unit temperature, thermal conductance, and thermal diffusivity of each subelement are the model inputs, as are the temperatures of each subelement. Numerical integration using the Finite in Time Centered in Space algorithm of the thermal diffusion equation is then performed in order to obtain a temporal evolution of the subelement temperature. Thermal transport across interfaces is modeled using a thermal boundary resistance obtained using the acoustic mismatch model. The document concludes with a discussion of the PoST fabrication. PoSTs are novel because they enable incident x-ray position sensitivity with good energy resolution and low wiring density.

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

Streza, M.; Dadarlat, D.; Strzałkowski, K.

An accurate determination of thermophysical properties such as thermal diffusivity, thermal effusivity and thermal conductivity is extremely important for characterization and quality assurance of semiconductors. Thermal diffusivity and effusivity of some binary semiconductors have been investigated. Two experimental techniques were used: a contact technique (PPE calorimetry) and a non contact technique (lock-in thermography). When working with PPE, in the back (BPPE) configuration and in the thermally thick regim of the pyroelectric sensor, we can get the thermal diffusivity of the sample by performing a scanning of the excitation frequency of radiation. Thermal effusivity is obtained in front configuration (sensor directlymore » irradiated and sample in back position) by performing a thickness scan of a coupling fluid. By using the lock-in thermography technique, the thermal diffusivity of the sample is obtained from the phase image. The results obtained by the two techniques are in good agreement. Nevertheless, for the determination of thermal diffusivity, lock-in thermography is preferred.« less

Local effect of compression stockings on skin microcirculatory activity through the measurement of skin effective thermal conductivity.

PubMed

Grenier, Etienne; Gehin, Claudine; Lun, Bertrand; McAdams, Eric

2013-01-01

This paper presents a preliminary study to demonstrate the instantaneous local effect of compression stocking (Class 2) on skin microcirculatory activity. The measurement needs to be carefully performed as the sensor is placed under the garment. To assess the local effect of compression stockings, we use the ambulatory device Hematron located on the calf under the garment. Skin microcirculatory activity is assessed through the skin's effective thermal conductivity measurement. A specific housing for the sensor has been designed to avoid excessive pressure induced by the sensor when squeezed by stockings. The experiment, conducted on ten healthy subjects, comprised two stages: without and with compression stockings. Skin effective thermal conductivity was recorded at three successive positions (supine, sitting and standing). Significant improvement in skin microcirculatory activity was recorded by the Hematron device for the three positions. We have also demonstrated that Hematron sensor can be used under compression stockings.

Research study of pressure instrumentation

NASA Technical Reports Server (NTRS)

Hoogenboom, L.; Hull-Allen, G.

1984-01-01

To obtain a more vibration resistant pressure sensor for use on the Space Shuttle Main Engine, a proximity probe based, diaphragm type pressure sensor breadboard was developed. A fiber optic proximity probe was selected as the sensor. In combination with existing electronics, a thermal stability evaluation of the entire probe system was made. Based upon the results, a breadboard design of the pressure sensor and electronics was made and fabricated. A brief series of functional experiments was made with the breadboard to calibrate, thermally compensate, and linearize its response. In these experiments, the performance obtained in the temperature range of -320 F (liquid N2) to +200 F was comparable to that of the strain gage based sensor presently in use on the engine. In tests at NASA-Marshall Space Flight Center (MSFC), after some time at or near liquid nitrogen temperatures, the sensor output varied over the entire output range. These large spurious signals were attributed to condensation of air in the sensing gap. In the next phase of development of this sensor, an evaluation of fabrication techniques toward greater thermal and mechanical stability of the fiber probe assembly must be made. In addition to this, a positive optics to metal seal must be developed to withstand the pressure that would result from a diaphragm failure.

A Micro-Thermal Sensor for Focal Therapy Applications

NASA Astrophysics Data System (ADS)

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

2016-02-01

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).

Thermal luminescence spectroscopy chemical imaging sensor.

PubMed

Carrieri, Arthur H; Buican, Tudor N; Roese, Erik S; Sutter, James; Samuels, Alan C

2012-10-01

The authors present a pseudo-active chemical imaging sensor model embodying irradiative transient heating, temperature nonequilibrium thermal luminescence spectroscopy, differential hyperspectral imaging, and artificial neural network technologies integrated together. We elaborate on various optimizations, simulations, and animations of the integrated sensor design and apply it to the terrestrial chemical contamination problem, where the interstitial contaminant compounds of detection interest (analytes) comprise liquid chemical warfare agents, their various derivative condensed phase compounds, and other material of a life-threatening nature. The sensor must measure and process a dynamic pattern of absorptive-emissive middle infrared molecular signature spectra of subject analytes to perform its chemical imaging and standoff detection functions successfully.

A hybrid electronically scanned pressure module for cryogenic environments

NASA Technical Reports Server (NTRS)

Chapman, J. J.; Hopson, P., Jr.; Kruse, N.

1995-01-01

Pressure is one of the most important parameters measured when testing models in wind tunnels. For models tested in the cryogenic environment of the National Transonic Facility at NASA Langley Research Center, the technique of utilizing commercially available multichannel pressure modules inside the models is difficult due to the small internal volume of the models and the requirement of keeping the pressure transducer modules within an acceptable temperature range well above the -173 degrees C tunnel temperature. A prototype multichannel pressure transducer module has been designed and fabricated with stable, repeatable sensors and materials optimized for reliable performance in the cryogenic environment. The module has 16 single crystal silicon piezoresistive pressure sensors electrostatically bonded to a metalized Pyrex substrate for sensing the wind tunnel model pressures. An integral temperature sensor mounted on each silicon micromachined pressure sensor senses real-time temperature fluctuations to within 0.1 degrees C to correct for thermally induced non-random sensor drift. The data presented here are from a prototype sensor module tested in the 0.3 M cryogenic tunnel and thermal equilibrium conditions in an environmental chamber which approximates the thermal environment (-173 degrees C to +60 degrees C) of the National Transonic Facility.

Piezoresistive Composite Silicon Dioxide Nanocantilever Surface Stress Sensor: Design and Optimization.

PubMed

Mathew, Ribu; Sankar, A Ravi

2018-05-01

In this paper, we present the design and optimization of a rectangular piezoresistive composite silicon dioxide nanocantilever sensor. Unlike the conventional design approach, we perform the sensor optimization by not only considering its electro-mechanical response but also incorporating the impact of self-heating induced thermal drift in its terminal characteristics. Through extensive simulations first we comprehend and quantify the inaccuracies due to self-heating effect induced by the geometrical and intrinsic parameters of the piezoresistor. Then, by optimizing the ratio of electrical sensitivity to thermal sensitivity defined as the sensitivity ratio (υ) we improve the sensor performance and measurement reliability. Results show that to ensure υ ≥ 1, shorter and wider piezoresistors are better. In addition, it is observed that unlike the general belief that high doping concentration of piezoresistor reduces thermal sensitivity in piezoresistive sensors, to ensure υ ≥ 1 doping concentration (p) should be in the range: 1E18 cm-3 ≤ p ≤ 1E19 cm-3. Finally, we provide a set of design guidelines that will help NEMS engineers to optimize the performance of such sensors for chemical and biological sensing applications.

High-Temperature Strain Sensing for Aerospace Applications

NASA Technical Reports Server (NTRS)

Piazza, Anthony; Richards, Lance W.; Hudson, Larry D.

2008-01-01

Thermal protection systems (TPS) and hot structures are utilizing advanced materials that operate at temperatures that exceed abilities to measure structural performance. Robust strain sensors that operate accurately and reliably beyond 1800 F are needed but do not exist. These shortcomings hinder the ability to validate analysis and modeling techniques and hinders the ability to optimize structural designs. This presentation examines high-temperature strain sensing for aerospace applications and, more specifically, seeks to provide strain data for validating finite element models and thermal-structural analyses. Efforts have been made to develop sensor attachment techniques for relevant structural materials at the small test specimen level and to perform laboratory tests to characterize sensor and generate corrections to apply to indicated strains. Areas highlighted in this presentation include sensors, sensor attachment techniques, laboratory evaluation/characterization of strain measurement, and sensor use in large-scale structures.

Development of a self-packaged 2D MEMS thermal wind sensor for low power applications

NASA Astrophysics Data System (ADS)

Zhu, Yan-qing; Chen, Bei; Qin, Ming; Huang, Jian-qiu; Huang, Qing-an

2015-08-01

This article describes the design, fabrication, and testing of a self-packaged 2D thermal wind sensor. The sensor consists of four heaters and nine thermistors. A central thermistor senses the average heater temperature, whereas the other eight, which are distributed symmetrically around the heaters, measure the temperature differences between the upstream and downstream surface of the sensor. The sensor was realized on one side of a silicon-in-glass (SIG) substrate. Vertical silicon vias in the substrate ensure good thermal contact between the sensor and the airflow and the glass effectively isolates the heaters from the thermistors. The substrate was fabricated by using a glass reflow process, after which the sensor was realized by a lift-off process. The sensor’s geometry was investigated with the help of simulations. These show that narrow heaters, moderate heater spacing, and thin substrates all improve the sensor’s sensitivity. Finally, the sensor was tested and calibrated in a wind tunnel by using a linear interpolation algorithm. At a constant heating power of 24.5 mW, measurement results show that the sensor can detect airflow speeds of up to 25 m s-1, with an accuracy of 0.1 m s-1 at low speeds and 0.5 m s-1 at high speeds. Airflow direction can be determined in a range of 360° with an accuracy of ±6°.

Investigations on the Impact of Material-Integrated Sensors with the Help of FEM-Based Modeling

PubMed Central

Dumstorff, Gerrit; Lang, Walter

2015-01-01

We present investigations on the impact of material-integrated sensors with the help of finite element-based modeling. A sensor (inlay) integrated with a material (matrix) is always a foreign body in the material, which can lead to a “wound effect”, that is degradation of the macroscopic behavior of a material. By analyzing the inlay's impact on the material in terms of mechanical load, heat conduction, stress during integration and other impacts of integration, this wound effect is analyzed. For the mechanical load, we found out that the inlay has to be at least as stretchable and bendable as the matrix. If there is a high thermal load during integration, the coefficients of the thermal expansion of the inlay have to be matched to the matrix. In the case of a high thermal load during operation, the inlay has to be as thin as possible or its thermal conductivity has to be adapted to the thermal conductivity of the matrix. To have a general view of things, the results are dimensionless and independent of the geometry. In each section, the results are illustrated by examples. Based on all of the results, we present our idea for the fabrication of future material-integrated sensors. PMID:25621607

Thermal control design of the Lightning Mapper Sensor narrow-band spectral filter

NASA Technical Reports Server (NTRS)

Flannery, Martin R.; Potter, John; Raab, Jeff R.; Manlief, Scott K.

1992-01-01

The performance of the Lightning Mapper Sensor is dependent on the temperature shifts of its narrowband spectral filter. To perform over a 10 degree FOV with an 0.8 nm bandwidth, the filter must be 15 cm in diameter and mounted externally to the telescope optics. The filter thermal control required a filter design optimized for minimum bandpass shift with temperature, a thermal analysis of substrate materials for maximum temperature uniformity, and a thermal radiation analysis to determine the parameter sensitivity of the radiation shield for the filter, the filter thermal recovery time after occultation, and heater power to maintain filter performance in the earth-staring geosynchronous environment.

Turbine blade and vane heat flux sensor development, phase 1

NASA Technical Reports Server (NTRS)

Atkinson, W. H.; Cyr, M. A.; Strange, R. R.

1984-01-01

Heat flux sensors available for installation in the hot section airfoils of advanced aircraft gas turbine engines were developed. Two heat flux sensors were designed, fabricated, calibrated, and tested. Measurement techniques are compared in an atmospheric pressure combustor rig test. Sensors, embedded thermocouple and the Gordon gauge, were fabricated that met the geometric and fabricability requirements and could withstand the hot section environmental conditions. Calibration data indicate that these sensors yielded repeatable results and have the potential to meet the accuracy goal of measuring local heat flux to within 5%. Thermal cycle tests and thermal soak tests indicated that the sensors are capable of surviving extended periods of exposure to the environment conditions in the turbine. Problems in calibration of the sensors caused by severe non-one dimensional heat flow were encountered. Modifications to the calibration techniques are needed to minimize this problem and proof testing of the sensors in an engine is needed to verify the designs.

Turbine blade and vane heat flux sensor development, phase 1

NASA Astrophysics Data System (ADS)

Atkinson, W. H.; Cyr, M. A.; Strange, R. R.

1984-08-01

Heat flux sensors available for installation in the hot section airfoils of advanced aircraft gas turbine engines were developed. Two heat flux sensors were designed, fabricated, calibrated, and tested. Measurement techniques are compared in an atmospheric pressure combustor rig test. Sensors, embedded thermocouple and the Gordon gauge, were fabricated that met the geometric and fabricability requirements and could withstand the hot section environmental conditions. Calibration data indicate that these sensors yielded repeatable results and have the potential to meet the accuracy goal of measuring local heat flux to within 5%. Thermal cycle tests and thermal soak tests indicated that the sensors are capable of surviving extended periods of exposure to the environment conditions in the turbine. Problems in calibration of the sensors caused by severe non-one dimensional heat flow were encountered. Modifications to the calibration techniques are needed to minimize this problem and proof testing of the sensors in an engine is needed to verify the designs.

Microscale out-of-plane anemometer

NASA Technical Reports Server (NTRS)

Liu, Chang (Inventor); Chen, Jack (Inventor)

2005-01-01

A microscale out-of-plane thermal sensor. A resistive heater is suspended over a substrate by supports raised with respect to the substrate to provide a clearance underneath the resistive heater for fluid flow. A preferred fabrication process for the thermal sensor uses surface micromachining and a three-dimensional assembly to raise the supports and lift the resistive heater over the substrate.

Evaluation of platinum resistance thermometers

NASA Technical Reports Server (NTRS)

Daryabeigi, Kamran; Dillon-Townes, Lawrence A.

1988-01-01

An evaluation procedure for the characterization of industrial platinum resistance thermometers (PRTs) for use in the temperature range -120 to 160 C was investigated. This evaluation procedure consisted of calibration, thermal stability and hysteresis testing of four surface measuring PRTs. Five different calibration schemes were investigated for these sensors. The IPTS-68 formulation produced the most accurate result, yielding average sensor systematic error of 0.02 C and random error of 0.1 C. The sensors were checked for thermal stability by successive and thermal cycling between room temperature, 160 C, and boiling point of nitrogen. All the PRTs suffered from instability and hysteresis. The applicability of the self-heating technique as an in situ method for checking the calibration of PRTs located inside wind tunnels was investigated.

A thermal sensor and switch based on a plasma polymer/ZnO suspended nanobelt bimorph structure

NASA Astrophysics Data System (ADS)

He, -Hau, Jr.; Singamaneni, Srikanth; Ho, Chih H.; Lin, Yen-Hsi; McConney, Michael E.; Tsukruk, Vladimir V.

2009-02-01

The combination of design and subsequent fabrication of organic/inorganic nanostructures creates an effective way to combine the favorable traits of both to achieve a desired device performance. We demonstrate a miniature electrical read-out, and a sensitive temperature sensor/switch, based on a ZnO nanobelt/plasma-polymerized benzonitrile bimorph structure. A new read-out technique based on the change in the electric current flowing through the bimorph and the contact pad has been employed, replacing the conventional cumbersome piezoresistive method or tedious optical alignment. The thermal sensor demonstrated here has great prospects for thermal switching and triggered detection owing to the relative ease in the fabrication of arrays and the direct electrical read-out.

Mars 2020 Entry, Descent and Landing Instrumentation 2 (MEDLI2)

NASA Technical Reports Server (NTRS)

Hwang, Helen H.; Bose, Deepak; White, Todd R.; Wright, Henry S.; Schoenenberger, Mark; Kuhl, Christopher A.; Trombetta, Dominic; Santos, Jose A.; Oishi, Tomomi; Karlgaard, Christopher D.;

Characterization of Sodium Thermal Hydraulics with Optical Fiber Temperature Sensors

NASA Astrophysics Data System (ADS)

Weathered, Matthew Thomas

The thermal hydraulic properties of liquid sodium make it an attractive coolant for use in Generation IV reactors. The liquid metal's high thermal conductivity and low Prandtl number increases efficiency in heat transfer at fuel rods and heat exchangers, but can also cause features such as high magnitude temperature oscillations and gradients in the coolant. Currently, there exists a knowledge gap in the mechanisms which may create these features and their effect on mechanical structures in a sodium fast reactor. Two of these mechanisms include thermal striping and thermal stratification. Thermal striping is the oscillating temperature field created by the turbulent mixing of non-isothermal flows. Usually this occurs at the reactor core outlet or in piping junctions and can cause thermal fatigue in mechanical structures. Meanwhile, thermal stratification results from large volumes of non-isothermal sodium in a pool type reactor, usually caused by a loss of coolant flow accident. This stratification creates buoyancy driven flow transients and high temperature gradients which can also lead to thermal fatigue in reactor structures. In order to study these phenomena in sodium, a novel method for the deployment of optical fiber temperature sensors was developed. This method promotes rapid thermal response time and high spatial temperature resolution in the fluid. The thermal striping and stratification behavior in sodium may be experimentally analyzed with these sensors with greater fidelity than ever before. Thermal striping behavior at a junction of non-isothermal sodium was fully characterized with optical fibers. An experimental vessel was hydrodynamically scaled to model thermal stratification in a prototypical sodium reactor pool. Novel auxiliary applications of the optical fiber temperature sensors were developed throughout the course of this work. One such application includes local convection coefficient determination in a vessel with the corollary application of level sensing. Other applications were cross correlation velocimetry to determine bulk sodium flow rate and the characterization of coherent vortical structures in sodium with temperature frequency data. The data harvested, instrumentation developed and techniques refined in this work will help in the design of more robust reactors as well as validate computational models for licensing sodium fast reactors.

Spider Silk Spun and Integrated into Composites

DTIC Science & Technology

2009-02-20

and elongation of sericin is lower than those of fibroin and, finally, (0 local shear damage is dominant in damaged sericin between fibres, while the... sericin at fibre-joint often shows microflow. These analytical studies are presently being expanded to include synthetic composites made of both...with sericin . Such a cocoon consists of three main parts: an outermost loose mesh structure, the middle shell layers and the innermost tetelette; all

Koch–Haaf reaction of adamantanols in an acid-tolerant hastelloy-made microreactor

PubMed Central

Mukai, Yu

2011-01-01

Summary The Koch–Haaf reaction of adamantanols was successfully carried out in a microflow system at room temperature. By combining an acid-tolerant hastelloy-made micromixer, a PTFE tube, and a hastelloy-made microextraction unit, a packaged reaction-to-workup system was developed. By means of the present system, the multigram scale synthesis of 1-adamantanecarboxylic acid was achieved in ca. one hour operation. PMID:21977213

Boundary layer separation and reattachment detection on airfoils by thermal flow sensors.

PubMed

Sturm, Hannes; Dumstorff, Gerrit; Busche, Peter; Westermann, Dieter; Lang, Walter

2012-10-24

A sensor concept for detection of boundary layer separation (flow separation, stall) and reattachment on airfoils is introduced in this paper. Boundary layer separation and reattachment are phenomena of fluid mechanics showing characteristics of extinction and even inversion of the flow velocity on an overflowed surface. The flow sensor used in this work is able to measure the flow velocity in terms of direction and quantity at the sensor's position and expected to determine those specific flow conditions. Therefore, an array of thermal flow sensors has been integrated (flush-mounted) on an airfoil and placed in a wind tunnel for measurement. Sensor signals have been recorded at different wind speeds and angles of attack for different positions on the airfoil. The sensors used here are based on the change of temperature distribution on a membrane (calorimetric principle). Thermopiles are used as temperature sensors in this approach offering a baseline free sensor signal, which is favorable for measurements at zero flow. Measurement results show clear separation points (zero flow) and even negative flow values (back flow) for all sensor positions. In addition to standard silicon-based flow sensors, a polymer-based flexible approach has been tested showing similar results.

Boundary Layer Separation and Reattachment Detection on Airfoils by Thermal Flow Sensors

PubMed Central

Sturm, Hannes; Dumstorff, Gerrit; Busche, Peter; Westermann, Dieter; Lang, Walter

2012-01-01

A sensor concept for detection of boundary layer separation (flow separation, stall) and reattachment on airfoils is introduced in this paper. Boundary layer separation and reattachment are phenomena of fluid mechanics showing characteristics of extinction and even inversion of the flow velocity on an overflowed surface. The flow sensor used in this work is able to measure the flow velocity in terms of direction and quantity at the sensor's position and expected to determine those specific flow conditions. Therefore, an array of thermal flow sensors has been integrated (flush-mounted) on an airfoil and placed in a wind tunnel for measurement. Sensor signals have been recorded at different wind speeds and angles of attack for different positions on the airfoil. The sensors used here are based on the change of temperature distribution on a membrane (calorimetric principle). Thermopiles are used as temperature sensors in this approach offering a baseline free sensor signal, which is favorable for measurements at zero flow. Measurement results show clear separation points (zero flow) and even negative flow values (back flow) for all sensor positions. In addition to standard silicon-based flow sensors, a polymer-based flexible approach has been tested showing similar results. PMID:23202160

Hot wire needle probe for thermal conductivity detection

DOEpatents

Condie, Keith Glenn; Rempe, Joy Lynn; Knudson, Darrell lee; Daw, Joshua Earl; Wilkins, Steven Curtis; Fox, Brandon S.; Heng, Ban

2015-11-10

An apparatus comprising a needle probe comprising a sheath, a heating element, a temperature sensor, and electrical insulation that allows thermal conductivity to be measured in extreme environments, such as in high-temperature irradiation testing. The heating element is contained within the sheath and is electrically conductive. In an embodiment, the heating element is a wire capable of being joule heated when an electrical current is applied. The temperature sensor is contained within the sheath, electrically insulated from the heating element and the sheath. The electrical insulation electrically insulates the sheath, heating element and temperature sensor. The electrical insulation fills the sheath having electrical resistance capable of preventing electrical conduction between the sheath, heating element, and temperature sensor. The control system is connected to the heating element and the temperature sensor.

ATTIRE (analytical tools for thermal infrared engineering): A sensor simulation and modeling package

NASA Astrophysics Data System (ADS)

Jaggi, S.

1993-02-01

The Advanced Sensor Development Laboratory (ASDL) at the Stennis Space Center develops, maintains and calibrates remote sensing instruments for the National Aeronautics & Space Administration (NASA). To perform system design trade-offs, analysis, and establish system parameters, ASDL has developed a software package for analytical simulation of sensor systems. This package called 'Analytical Tools for Thermal InfraRed Engineering' - ATTIRE, simulates the various components of a sensor system. The software allows each subsystem of the sensor to be analyzed independently for its performance. These performance parameters are then integrated to obtain system level information such as Signal-to-Noise Ratio (SNR), Noise Equivalent Radiance (NER), Noise Equivalent Temperature Difference (NETD) etc. This paper describes the uses of the package and the physics that were used to derive the performance parameters.

Impact of Reflow on the Output Characteristics of Piezoelectric Microelectromechanical System Devices

NASA Astrophysics Data System (ADS)

Nogami, Hirofumi; Kobayashi, Takeshi; Okada, Hironao; Masuda, Takashi; Maeda, Ryutaro; Itoh, Toshihiro

2012-09-01

An animal health monitoring system and a wireless sensor node aimed at preventing the spread of animal-transmitted diseases and improving pastoral efficiency which are especially suitable for chickens, were developed. The sensor node uses a piezoelectric microelectromechanical system (MEMS) device and an event-driven system that is activated by the movements of a chicken. The piezoelectric MEMS device has two functions: a) it measures the activity of a chicken and b) switches the micro-control unit (MCU) of the wireless sensor node from the sleep mode. The piezoelectric MEMS device is required to produce high output voltages when the chicken moves. However, after the piezoelectric MEMS device was reflowed to the wireless sensor node, the output voltages of the piezoelectric MEMS device decreased. The main reason for this might be the loss of residual polarization, which is affected by the thermal load during the reflow process. After the reflow process, we were not able to apply a voltage to the piezoelectric MEMS device; thus, the piezoelectric output voltage was not increased by repoling the piezoelectric MEMS device. To address the thermal load of the reflow process, we established a thermal poling treatment, which achieves a higher temperature than the reflow process. We found that on increasing the thermal poling temperature, the piezoelectric output voltages did not decreased low significantly. Thus, we considered that a thermal poling temperature higher than that of the reflow process prevents the piezoelectric output voltage reduction caused by the thermal load.

Thermal camera used for the assessment of metabolism and functions of the rat brain

NASA Astrophysics Data System (ADS)

Kastek, Mariusz; Piatkowski, Tadeusz; Polakowski, Henryk; Kaczmarska, Katarzyna; Czernicki, Zbigniew; Koźniewska, Ewa; Przykaza, Lukasz

2014-05-01

Motivation to undertake research on brain surface temperature in clinical practice is based on a strong conviction that the enormous progress in thermal imaging techniques and camera design has a great application potential. Intraoperative imaging of pathological changes and functionally important areas of the brain is not yet fully resolved in neurosurgery and remains a challenge. Extensive knowledge of the complex mechanisms controlling homeostasis (thermodynamic status of an organism being a part of it ) and laws of physics (which are the foundations of thermography), make this method very good and a simple imaging tool in comparison with other modern techniques, such as computed tomography, magnetic resonance imaging and angiography. Measurements of temperature distribution across the brain surface were performed on four rats (Wistar strain) weighing approximately 300 g each. Animals have remained under general anesthesia typically conducted using isoflurane. The brain was unveiled (the dura mater remained untouched) through the skin incision and removal of the bone cranial vault. Cerebrocortical microflow was measured using laser-Doppler flow meter. Arterial blood pressure was also measured in rat femoral artery. From the above data the cerebrovascular resistance index was calculated. Cerebral flow was modified by increasing the CO2 concentration in the inspired air to 5% for the duration of 6 minutes. Another change in cerebral flow was induced by periodic closing of right middle cerebral artery. Artery occlusion was performed by introducing a filament for a period of 15 minutes, then an artery was opened again. Measurements were carried out before, during and after the artery occlusion. Paper presents results and methodology of measurements.

Evaluation of a Sensor System for Detecting Humans Trapped under Rubble: A Pilot Study

PubMed Central

Kasai, Ritaro; Cosentino, Sarah; Giacomo, Cimarelli; Mochida, Yasuaki; Yamada, Hiroya; Guarnieri, Michele; Takanishi, Atsuo

2018-01-01

Rapid localization of injured survivors by rescue teams to prevent death is a major issue. In this paper, a sensor system for human rescue including three different types of sensors, a CO2 sensor, a thermal camera, and a microphone, is proposed. The performance of this system in detecting living victims under the rubble has been tested in a high-fidelity simulated disaster area. Results show that the CO2 sensor is useful to effectively reduce the possible concerned area, while the thermal camera can confirm the correct position of the victim. Moreover, it is believed that the use of microphones in connection with other sensors would be of great benefit for the detection of casualties. In this work, an algorithm to recognize voices or suspected human noise under rubble has also been developed and tested. PMID:29534055

Miniature all-silica optical fiber pressure sensor with an ultrathin uniform diaphragm.

PubMed

Wang, Wenhui; Wu, Nan; Tian, Ye; Niezrecki, Christopher; Wang, Xingwei

2010-04-26

This paper presents an all-silica miniature optical fiber pressure/acoustic sensor based on the Fabry-Perot (FP) interferometric principle. The endface of the etched optical fiber tip and silica thin diaphragm on it form the FP structure. The uniform and thin silica diaphragm was fabricated by etching away the silicon substrate from a commercial silicon wafer that has a thermal oxide layer. The thin film was directly thermally bonded to the endface of the optical fiber thus creating the Fabry-Perot cavity. Thin films with a thickness from 1microm to 3microm have been bonded successfully. The sensor shows good linearity and hysteresis during measurement. A sensor with 0.75 microm-thick diaphragm thinned by post silica etching was demonstrated to have a sensitivity of 11 nm/kPa. The new sensor has great potential to be used as a non-intrusive pressure sensor in a variety of sensing applications.

Thermal sensors utilizing thin layer technology applied to the analysis of aeronautical thermal exchanges

NASA Astrophysics Data System (ADS)

Godefroy, J. C.; Gageant, C.; Francois, D.

Thin film surface thermometers and thermal gradient fluxmeters developed by ONERA to monitor thermal exchanges in aircraft engines to predict the remaining service life of the components are described. The sensors, less than 80 microns thick, with flexible Kapton dielectric layers and metal substrates, are integrated into the shape of the surface being monitored. Features of Cu-n, Ni-, Au-, and Cr-based films, including mounting and circuitry methods that permit calibration and accurate signal analysis, are summarized. Results are discussed from sample applications of the devices on a symmetric NACA 65(1)-012 airfoil and on a turbine blade.

Fiber Bragg grating temperature sensors in a 6.5-MW generator exciter bridge and the development and simulation of its thermal model.

PubMed

de Morais Sousa, Kleiton; Probst, Werner; Bortolotti, Fernando; Martelli, Cicero; da Silva, Jean Carlos Cardozo

2014-09-05

This work reports the thermal modeling and characterization of a thyristor. The thyristor is used in a 6.5-MW generator excitation bridge. Temperature measurements are performed using fiber Bragg grating (FBG) sensors. These sensors have the benefits of being totally passive and immune to electromagnetic interference and also multiplexed in a single fiber. The thyristor thermal model consists of a second order equivalent electric circuit, and its power losses lead to an increase in temperature, while the losses are calculated on the basis of the excitation current in the generator. Six multiplexed FBGs are used to measure temperature and are embedded to avoid the effect of the strain sensitivity. The presented results show a relationship between field current and temperature oscillation and prove that this current can be used to determine the thermal model of a thyristor. The thermal model simulation presents an error of 1.5 °C, while the FBG used allows for the determination of the thermal behavior and the field current dependence. Since the temperature is a function of the field current, the corresponding simulation can be used to estimate the temperature in the thyristors.

Fiber Bragg Grating Temperature Sensors in a 6.5-MW Generator Exciter Bridge and the Development and Simulation of Its Thermal Model

PubMed Central

de Morais Sousa, Kleiton; Probst, Werner; Bortolotti, Fernando; Martelli, Cicero; da Silva, Jean Carlos Cardozo

2014-01-01

This work reports the thermal modeling and characterization of a thyristor. The thyristor is used in a 6.5-MW generator excitation bridge. Temperature measurements are performed using fiber Bragg grating (FBG) sensors. These sensors have the benefits of being totally passive and immune to electromagnetic interference and also multiplexed in a single fiber. The thyristor thermal model consists of a second order equivalent electric circuit, and its power losses lead to an increase in temperature, while the losses are calculated on the basis of the excitation current in the generator. Six multiplexed FBGs are used to measure temperature and are embedded to avoid the effect of the strain sensitivity. The presented results show a relationship between field current and temperature oscillation and prove that this current can be used to determine the thermal model of a thyristor. The thermal model simulation presents an error of 1.5 °C, while the FBG used allows for the determination of the thermal behavior and the field current dependence. Since the temperature is a function of the field current, the corresponding simulation can be used to estimate the temperature in the thyristors. PMID:25198007

A waveguide-coupled thermally isolated radiometric source.

PubMed

Rostem, K; Chuss, D T; Lourie, N P; Voellmer, G M; Wollack, E J

2013-04-01

The design and validation of a dual polarization source for waveguide-coupled millimeter and sub-millimeter wave cryogenic sensors is presented. The thermal source is a waveguide mounted absorbing conical dielectric taper. The absorber is thermally isolated with a kinematic suspension that allows the guide to be heat sunk to the lowest bath temperature of the cryogenic system. This approach enables the thermal emission from the metallic waveguide walls to be subdominant to that from the source. The use of low thermal conductivity Kevlar threads for the kinematic mount effectively decouples the absorber from the sensor cold stage. Hence, the absorber can be heated to significantly higher temperatures than the sensor with negligible conductive loading. The kinematic suspension provides high mechanical repeatability and reliability with thermal cycling. A 33-50 GHz blackbody source demonstrates an emissivity of 0.999 over the full waveguide band where the dominant deviation from unity arises from the waveguide ohmic loss. The observed thermal time constant of the source is 40 s when the absorber temperature is 15 K. The specific heat of the lossy dielectric, MF-117, is well approximated by C(v)(T) = 0.12 T (2.06) mJ g(-1) K(-1) between 3.5 K and 15 K.

A Wide Range Temperature Sensor Using SOI Technology

NASA Technical Reports Server (NTRS)

Patterson, Richard L.; Elbuluk, Malik E.; Hammoud, Ahmad

2009-01-01

Silicon-on-insulator (SOI) technology is becoming widely used in integrated circuit chips for its advantages over the conventional silicon counterpart. The decrease in leakage current combined with lower power consumption allows electronics to operate in a broader temperature range. This paper describes the performance of an SOIbased temperature sensor under extreme temperatures and thermal cycling. The sensor comprised of a temperature-to-frequency relaxation oscillator circuit utilizing an SOI precision timer chip. The circuit was evaluated under extreme temperature exposure and thermal cycling between -190 C and +210 C. The results indicate that the sensor performed well over the entire test temperature range and it was able to re-start at extreme temperatures.

Weld Nugget Temperature Control in Thermal Stir Welding

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey (Inventor)

2014-01-01

A control system for a thermal stir welding system is provided. The control system includes a sensor and a controller. The sensor is coupled to the welding system's containment plate assembly and generates signals indicative of temperature of a region adjacent and parallel to the welding system's stir rod. The controller is coupled to the sensor and generates at least one control signal using the sensor signals indicative of temperature. The controller is also coupled to the welding system such that at least one of rotational speed of the stir rod, heat supplied by the welding system's induction heater, and feed speed of the welding system's weld material feeder are controlled based on the control signal(s).

Fiber Optic Sensors for Temperature Monitoring during Thermal Treatments: An Overview

PubMed Central

Schena, Emiliano; Tosi, Daniele; Saccomandi, Paola; Lewis, Elfed; Kim, Taesung

2016-01-01

During recent decades, minimally invasive thermal treatments (i.e., Radiofrequency ablation, Laser ablation, Microwave ablation, High Intensity Focused Ultrasound ablation, and Cryo-ablation) have gained widespread recognition in the field of tumor removal. These techniques induce a localized temperature increase or decrease to remove the tumor while the surrounding healthy tissue remains intact. An accurate measurement of tissue temperature may be particularly beneficial to improve treatment outcomes, because it can be used as a clear end-point to achieve complete tumor ablation and minimize recurrence. Among the several thermometric techniques used in this field, fiber optic sensors (FOSs) have several attractive features: high flexibility and small size of both sensor and cabling, allowing insertion of FOSs within deep-seated tissue; metrological characteristics, such as accuracy (better than 1 °C), sensitivity (e.g., 10 pm·°C−1 for Fiber Bragg Gratings), and frequency response (hundreds of kHz), are adequate for this application; immunity to electromagnetic interference allows the use of FOSs during Magnetic Resonance- or Computed Tomography-guided thermal procedures. In this review the current status of the most used FOSs for temperature monitoring during thermal procedure (e.g., fiber Bragg Grating sensors; fluoroptic sensors) is presented, with emphasis placed on their working principles and metrological characteristics. The essential physics of the common ablation techniques are included to explain the advantages of using FOSs during these procedures. PMID:27455273

Enabling Smart Air Conditioning by Sensor Development: A Review

PubMed Central

Cheng, Chin-Chi; Lee, Dasheng

2016-01-01

The study investigates the development of sensors, in particular the use of thermo-fluidic sensors and occupancy detectors, to achieve smart operation of air conditioning systems. Smart operation refers to the operation of air conditioners by the reinforcement of interaction to achieve both thermal comfort and energy efficiency. Sensors related to thermal comfort include those of temperature, humidity, and pressure and wind velocity anemometers. Improvements in their performance in the past years have been studied by a literature survey. Traditional occupancy detection using passive infra-red (PIR) sensors and novel methodologies using smartphones and wearable sensors are both discussed. Referring to the case studies summarized in this study, air conditioning energy savings are evaluated quantitatively. Results show that energy savings of air conditioners before 2000 was 11%, and 30% after 2000 by the integration of thermo-fluidic sensors and occupancy detectors. By utilizing wearable sensing to detect the human motions, metabolic rates and related information, the energy savings can reach up to 46.3% and keep the minimum change of predicted mean vote (∆PMV→0), which means there is no compromise in thermal comfort. This enables smart air conditioning to compensate for the large variations from person to person in terms of physiological and psychological satisfaction, and find an optimal temperature for everyone in a given space. However, this tendency should be evidenced by more experimental results in the future. PMID:27916906

Introduction to the Special Session on Thermal Remote Sensing Data for Earth Science Research: The Critical Need for Continued Data Collection and Development of Future Thermal Satellite Sensors

NASA Technical Reports Server (NTRS)

Quattrochi, Dale a.; Luvall, Jeffrey C.; Anderson, Martha; Hook, Simon

2006-01-01

There is a rich and long history of thermal infrared (TIR) remote sensing data for multidisciplinary Earth science research. The continuity of TIR data collection, however, is now in jeopardy given there are no planned future Earth observing TIR remote sensing satellite systems with moderately high spatial resolutions to replace those currently in orbit on NASA's Terra suite of sensors. This session will convene researchers who have actively worked in the field of TIR remote sensing to present results that elucidate the importance of thermal remote sensing to the wider Earth science research community. Additionally, this session will also exist as a forum for presenting concepts and ideas for new thermal sensing systems with high spatial resolutions for future Earth science satellite missions, as opposed to planned systems such as the Visible/Infrared Imager/Radiometer (VIIRS) suite of sensors on the National Polar-orbiting Operational Environmental Satellite System (NPOESS) that will collect TIR data at very coarse iairesolutions.

Smart Building: Decision Making Architecture for Thermal Energy Management.

PubMed

Uribe, Oscar Hernández; Martin, Juan Pablo San; Garcia-Alegre, María C; Santos, Matilde; Guinea, Domingo

2015-10-30

Smart applications of the Internet of Things are improving the performance of buildings, reducing energy demand. Local and smart networks, soft computing methodologies, machine intelligence algorithms and pervasive sensors are some of the basics of energy optimization strategies developed for the benefit of environmental sustainability and user comfort. This work presents a distributed sensor-processor-communication decision-making architecture to improve the acquisition, storage and transfer of thermal energy in buildings. The developed system is implemented in a near Zero-Energy Building (nZEB) prototype equipped with a built-in thermal solar collector, where optical properties are analysed; a low enthalpy geothermal accumulation system, segmented in different temperature zones; and an envelope that includes a dynamic thermal barrier. An intelligent control of this dynamic thermal barrier is applied to reduce the thermal energy demand (heating and cooling) caused by daily and seasonal weather variations. Simulations and experimental results are presented to highlight the nZEB thermal energy reduction.

Optical Sensors for Monitoring Gamma and Neutron Radiation

NASA Technical Reports Server (NTRS)

Boyd, Clark D.

2011-01-01

For safety and efficiency, nuclear reactors must be carefully monitored to provide feedback that enables the fission rate to be held at a constant target level via adjustments in the position of neutron-absorbing rods and moderating coolant flow rates. For automated reactor control, the monitoring system should provide calibrated analog or digital output. The sensors must survive and produce reliable output with minimal drift for at least one to two years, for replacement only during refueling. Small sensor size is preferred to enable more sensors to be placed in the core for more detailed characterization of the local fission rate and fuel consumption, since local deviations from the norm tend to amplify themselves. Currently, reactors are monitored by local power range meters (LPRMs) based on the neutron flux or gamma thermometers based on the gamma flux. LPRMs tend to be bulky, while gamma thermometers are subject to unwanted drift. Both electronic reactor sensors are plagued by electrical noise induced by ionizing radiation near the reactor core. A fiber optic sensor system was developed that is capable of tracking thermal neutron fluence and gamma flux in order to monitor nuclear reactor fission rates. The system provides near-real-time feedback from small- profile probes that are not sensitive to electromagnetic noise. The key novel feature is the practical design of fiber optic radiation sensors. The use of an actinoid element to monitor neutron flux in fiber optic EFPI (extrinsic Fabry-Perot interferometric) sensors is a new use of material. The materials and structure used in the sensor construction can be adjusted to result in a sensor that is sensitive to just thermal, gamma, or neutron stimulus, or any combination of the three. The tested design showed low sensitivity to thermal and gamma stimuli and high sensitivity to neutrons, with a fast response time.

75 FR 47176 - Special Conditions: Dassault Aviation Model Falcon 7X; Enhanced Flight Visibility System (EFVS)

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-05

...), imaging sensor(s), and avionics interfaces that display the sensor imagery on the HUD and overlay it with... that display the sensor imagery, with or without other flight information, on a head-down display. To... infrared sensors can be much different from that detected by natural pilot vision. On a dark night, thermal...

Fiber Optic Thermal Health Monitoring of Composites

NASA Technical Reports Server (NTRS)

Wu, Meng-Chou; Winfree, William P.; Moore, Jason P.

2010-01-01

A recently developed technique is presented for thermographic detection of flaws in composite materials by performing temperature measurements with fiber optic Bragg gratings. Individual optical fibers with multiple Bragg gratings employed as surface temperature sensors were bonded to the surfaces of composites with subsurface defects. The investigated structures included a 10-ply composite specimen with subsurface delaminations of various sizes and depths. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The data obtained from grating sensors were analyzed with thermal modeling techniques of conventional thermography to reveal particular characteristics of the interested areas. Results were compared with the calculations using numerical simulation techniques. Methods and limitations for performing in-situ structural health monitoring are discussed.

Luminescent sensors for tracking spatial particle distributions in an explosion

NASA Astrophysics Data System (ADS)

Anderson, Benjamin R.; Gunawidjaja, Ray; Diez-y-Riega, Helena; Eilers, Hergen; Svingala, Forrest R.; Daniels, Amber; Lightstone, James M.

2017-01-01

We previously developed and tested thermally sensitive particles that, when seeded into an explosive event, flow with the expanding post-detonation fireball and provide ex-situ measurements of this thermal environment. This current work presents the development and testing of tracking particles that are used in concert with the thermally sensitive particles to encode the initial positions of materials recovered for ex-situ analysis. These tracking sensors consist of fully-crystallized (c) rare-earth-doped yttria particles such as c-Dy:Y2O3, c-Sm:Y2O3, and c-Er,Yb:Y2O3. The temperature sensors consist of mixtures of precursor (p) and fully crystallized materials such as p-Eu:Y2O3/c-Tb:Y2O3 or p-Eu:ZrO2. Three mixtures containing one of the tracking sensors and one of the temperature sensing mixtures are placed at different locations within the chamber. Post-detonation, the tracking particles in the debris are excited by 355 nm light, resulting in different color luminescence, and allowing for potential visual inspection of the particle distribution originating from the different locations. Meanwhile, the temperature is determined from spectral changes of the precursor sensor materials or by comparison of the precursor sensor materials with the Tb:Y2O3 intensity reference.

Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors.

PubMed

Jenkins, R Brian; Joyce, Peter; Mechtel, Deborah

2017-01-27

Fiber Bragg grating (FBG) temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initial tests are conducted on polymer matrix composites reinforced with either carbon or glass fiber with a single optical fiber embedded into each specimen. As many as three sensors in each optical fiber measure the temporal and spatial thermal response of the composite to high energy radiation incident on the surface. Additional tests use a 2 × 2 × 3 array of 12 sensors embedded in a carbon fiber/epoxy composite to simultaneously measure temperature variations at locations on the composite surface and through the thickness. Results indicate that FBGs can be used to rapidly detect temperature gradients in a composite and their location, even for a direct strike of laser radiation on a sensor, when high temperatures can cause a non-uniform thermal response and FBG decay.

Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors

PubMed Central

Jenkins, R. Brian; Joyce, Peter; Mechtel, Deborah

2017-01-01

Fiber Bragg grating (FBG) temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initial tests are conducted on polymer matrix composites reinforced with either carbon or glass fiber with a single optical fiber embedded into each specimen. As many as three sensors in each optical fiber measure the temporal and spatial thermal response of the composite to high energy radiation incident on the surface. Additional tests use a 2 × 2 × 3 array of 12 sensors embedded in a carbon fiber/epoxy composite to simultaneously measure temperature variations at locations on the composite surface and through the thickness. Results indicate that FBGs can be used to rapidly detect temperature gradients in a composite and their location, even for a direct strike of laser radiation on a sensor, when high temperatures can cause a non-uniform thermal response and FBG decay. PMID:28134815

Integrated fiber optical and thermal sensor for noninvasive monitoring of blood and human tissue

NASA Astrophysics Data System (ADS)

Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Schiffner, Gerhard

2007-05-01

A novel concept of noninvasive monitoring of human tissue and blood based on optical diffuse reflective spectroscopy combined with metabolic heat measurements has been under development. A compact integrated fiber optical and thermal sensor has been developed. The idea of the method was to evaluate by optical spectroscopy haemoglobin and derivative concentrations and supplement with data associated with the oxidative metabolism of glucose. Body heat generated by glucose oxidation is based on the balance of capillary glucose and oxygen supply to the cells. The variation in glucose concentration is followed also by a difference from a distance (or depth) of scattered through the body radiation. So, blood glucose can be estimated by measuring the body heat and the oxygen supply. The sensor pickup contains of halogen lamp and LEDs combined with fiber optical bundle to deliver optical radiation inside and through the patient body, optical and thermal detectors. Fiber optical probe allows diffuse scattering measurement down to a depth of 2.5 mm in the skin including vascular system, which contributes to the control of the body temperature. The sensor pickup measures thermal generation, heat balance, blood flow rate, haemoglobin and derivative concentrations, environmental conditions. Multivariate statistical analysis was applied to convert various signals from the sensor pickup into physicochemical variables. By comparing the values from the noninvasive measurement with the venous plasma result, analytical functions for patient were obtained. Cluster analysis of patient groups was used to simplify a calibration procedure. Clinical testing of developed sensor is being performed.

Structural health monitoring technology for bolted carbon-carbon thermal protection panels

NASA Astrophysics Data System (ADS)

Yang, Jinkyu

2005-12-01

The research in this dissertation is motivated by the need for reliable inspection technologies for the detection of bolt loosening in Carbon-Carbon (C-C) Thermal Protection System (TPS) panels on Space Operation Vehicles (SOV) using minimal human intervention. A concept demonstrator of the Structural Health Monitoring (SHM) system was developed to autonomously detect the degradation of the mechanical integrity of the standoff C-C TPS panels. This system assesses the torque levels of the loosened bolts in the C-C TPS panel, as well as identifies the location of those bolts accordingly. During the course of building the proposed SHM prototype, efforts have been focused primarily on developing a trustworthy diagnostic scheme and a responsive sensor suite. Based on the microcontact conditions and damping phenomena of ultrasonic waves across the bolted joints, an Attenuation-based Diagnostic Method was proposed to assess the fastener integrity by observing the attenuation patterns of the resultant sensor signals. Parametric model studies and prototype testing validated the theoretical explanation of the attenuation-based method. Once the diagnostic scheme was determined, the implementation of a sensor suite was the next step. A new PZT-embedded sensor washer was developed to enhance remote sensing capability and achieve sufficient sensitivity by guiding diagnostic waves primarily through the inspection areas. The sensor-embedded washers replace the existing washers to constitute the sensor network, as well as to avoid jeopardizing the integrity of the original fastener components. After sensor design evolution and appropriate algorithm development, verification tests were conducted using a shaker and a full-scale oven, which simulated the acoustic and thermal environments during the re-entry process, respectively. The test results revealed that the proposed system successfully identifies the loss of the preload for the bolted joints that were loosened. The sensors were also found to be durable under the cyclic mechanical and thermal loads without major failures.

Swap intensified WDR CMOS module for I2/LWIR fusion

NASA Astrophysics Data System (ADS)

Ni, Yang; Noguier, Vincent

2015-05-01

The combination of high resolution visible-near-infrared low light sensor and moderate resolution uncooled thermal sensor provides an efficient way for multi-task night vision. Tremendous progress has been made on uncooled thermal sensors (a-Si, VOx, etc.). It's possible to make a miniature uncooled thermal camera module in a tiny 1cm3 cube with <1W power consumption. For silicon based solid-state low light CCD/CMOS sensors have observed also a constant progress in terms of readout noise, dark current, resolution and frame rate. In contrast to thermal sensing which is intrinsic day&night operational, the silicon based solid-state sensors are not yet capable to do the night vision performance required by defense and critical surveillance applications. Readout noise, dark current are 2 major obstacles. The low dynamic range at high sensitivity mode of silicon sensors is also an important limiting factor, which leads to recognition failure due to local or global saturations & blooming. In this context, the image intensifier based solution is still attractive for the following reasons: 1) high gain and ultra-low dark current; 2) wide dynamic range and 3) ultra-low power consumption. With high electron gain and ultra low dark current of image intensifier, the only requirement on the silicon image pickup device are resolution, dynamic range and power consumption. In this paper, we present a SWAP intensified Wide Dynamic Range CMOS module for night vision applications, especially for I2/LWIR fusion. This module is based on a dedicated CMOS image sensor using solar-cell mode photodiode logarithmic pixel design which covers a huge dynamic range (> 140dB) without saturation and blooming. The ultra-wide dynamic range image from this new generation logarithmic sensor can be used directly without any image processing and provide an instant light accommodation. The complete module is slightly bigger than a simple ANVIS format I2 tube with <500mW power consumption.

VO2 nanorods for efficient performance in thermal fluids and sensors

NASA Astrophysics Data System (ADS)

Dey, Kajal Kumar; Bhatnagar, Divyanshu; Srivastava, Avanish Kumar; Wan, Meher; Singh, Satyendra; Yadav, Raja Ram; Yadav, Bal Chandra; Deepa, Melepurath

2015-03-01

VO2 (B) nanorods with average width ranging between 50-100 nm are synthesized via a hydrothermal method and the post hydrothermal treatment drying temperature is found to be influential in their overall phase and growth morphology evolution. The nanorods with unusually high optical bandgap for a VO2 material are effective in enhancing the thermal performance of ethylene glycol nanofluids over a wide temperature range as is indicated by the temperature dependent thermal conductivity measurements. Humidity and LPG sensors fabricated using the VO2 (B) nanorods bear testament to their efficient sensing performance, which can be partially attributed to the mesoporous nature of the nanorods.VO2 (B) nanorods with average width ranging between 50-100 nm are synthesized via a hydrothermal method and the post hydrothermal treatment drying temperature is found to be influential in their overall phase and growth morphology evolution. The nanorods with unusually high optical bandgap for a VO2 material are effective in enhancing the thermal performance of ethylene glycol nanofluids over a wide temperature range as is indicated by the temperature dependent thermal conductivity measurements. Humidity and LPG sensors fabricated using the VO2 (B) nanorods bear testament to their efficient sensing performance, which can be partially attributed to the mesoporous nature of the nanorods. Electronic supplementary information (ESI) available: Plots representing the actual ratio Knf/KEG (Knf is the thermal conductivity of the nanofluid and KEG being thermal conductivity of the base fluid) across the entire experimental temperature range of 20 to 80 °C, table representing a comparison of performance of the VO2 sensor towards different gases. See DOI: 10.1039/c4nr06032f

Cryogenic High Pressure Sensor Module

NASA Technical Reports Server (NTRS)

Chapman, John J. (Inventor); Shams, Qamar A. (Inventor); Powers, William T. (Inventor)

1999-01-01

A pressure sensor is provided for cryogenic, high pressure applications. A highly doped silicon piezoresistive pressure sensor is bonded to a silicon substrate in an absolute pressure sensing configuration. The absolute pressure sensor is bonded to an aluminum nitride substrate. Aluminum nitride has appropriate coefficient of thermal expansion for use with highly doped silicon at cryogenic temperatures. A group of sensors, either two sensors on two substrates or four sensors on a single substrate are packaged in a pressure vessel.

Cryogenic, Absolute, High Pressure Sensor

NASA Technical Reports Server (NTRS)

Chapman, John J. (Inventor); Shams. Qamar A. (Inventor); Powers, William T. (Inventor)

2001-01-01

A pressure sensor is provided for cryogenic, high pressure applications. A highly doped silicon piezoresistive pressure sensor is bonded to a silicon substrate in an absolute pressure sensing configuration. The absolute pressure sensor is bonded to an aluminum nitride substrate. Aluminum nitride has appropriate coefficient of thermal expansion for use with highly doped silicon at cryogenic temperatures. A group of sensors, either two sensors on two substrates or four sensors on a single substrate are packaged in a pressure vessel.

Downhole geothermal well sensors comprising a hydrogen-resistant optical fiber

DOEpatents

Weiss, Jonathan D.

2005-02-08

A new class of optical fiber based thermal sensors has been invented. The new sensors comprise hydrogen-resistant optical fibers which are able to withstand a hot, hydrogen-containing environment as is often found in the downhole well environment.

Detection of impact damage on thermal protection systems using thin-film piezoelectric sensors for integrated structural health monitoring

NASA Astrophysics Data System (ADS)

Na, Jeong K.; Kuhr, Samuel J.; Jata, Kumar V.

2008-03-01

Thermal Protection Systems (TPS) can be subjected to impact damage during flight and/or during ground maintenance and/or repair. AFRL/RXLP is developing a reliable and robust on-board sensing/monitoring capability for next generation thermal protection systems to detect and assess impact damage. This study was focused on two classes of metallic thermal protection tiles to determine threshold for impact damage and develop sensing capability of the impacts. Sensors made of PVDF piezoelectric film were employed and tested to evaluate the detectability of impact signals and assess the onset or threshold of impact damage. Testing was performed over a range of impact energy levels, where the sensors were adhered to the back of the specimens. The PVDF signal levels were analyzed and compared to assess damage, where digital microscopy, visual inspection, and white light interferometry were used for damage verification. Based on the impact test results, an assessment of the impact damage thresholds for each type of metallic TPS system was made.

Challenges of designing and testing a highly stable sensor platform: Cesic solves MTG star sensor bracket thermoelastic requirements

NASA Astrophysics Data System (ADS)

Kroedel, Matthias; Zauner, Christoph

2017-09-01

The Meteosat Third Generation's extreme pointing requirements call for a highly stable bracket for mounting the Star Trackers. HB-Cesic®, a chopped fibre reinforced silicon carbide, was selected as a base material for the sensor bracket. The high thermal conductivity and low thermal expansion of HB-Cesic® were the key properties to fulfil the demanding thermo-elastic pointing requirements of below 1μrad/K for the Star Trackers mounting interfaces. Dominated by thermoelastic stability requirements, the design and analysis of the Bracket required a multidisciplinary approach with the focus on thermal and thermo-elastic analyses. Dedicated modal and thermal post-processing strategies have been applied in the scope of the light weighting process. The experimental verification of this thermo-elastic stable system has been a challenging task of its own. A thermo-elastic distortion measurement rig was developed with a stability of <0.1μrad/K in all three rotational degrees of freedom.

Experimental Validation of Thermal Retinal Models of Damage from Laser Radiation

DTIC Science & Technology

1979-08-01

for measuring relative intensity profile with a thermocouple or fiber-optic sensor .............................................. 72 B-2 Calculated...relative intensity profiles meas- ured by 5- and 10-pm-radius sensors of a Gaussian beam, with standard deviation of 10 Pm...the Air Force de - veloped a model for the mathematical prediction of thermal ef- fects of laser radiation on the eye (8). Given the characteris- tics

Thermal effects on nonlinear vibration of a carbon nanotube-based mass sensor using finite element analysis

NASA Astrophysics Data System (ADS)

Kang, Dong-Keun; Kim, Chang-Wan; Yang, Hyun-Ik

2017-01-01

In the present study we carried out a dynamic analysis of a CNT-based mass sensor by using a finite element method (FEM)-based nonlinear analysis model of the CNT resonator to elucidate the combined effects of thermal effects and nonlinear oscillation behavior upon the overall mass detection sensitivity. Mass sensors using carbon nanotube (CNT) resonators provide very high sensing performance. Because CNT-based resonators can have high aspect ratios, they can easily exhibit nonlinear oscillation behavior due to large displacements. Also, CNT-based devices may experience high temperatures during their manufacture and operation. These geometrical nonlinearities and temperature changes affect the sensing performance of CNT-based mass sensors. However, it is very hard to find previous literature addressing the detection sensitivity of CNT-based mass sensors including considerations of both these nonlinear behaviors and thermal effects. We modeled the nonlinear equation of motion by using the von Karman nonlinear strain-displacement relation, taking into account the additional axial force associated with the thermal effect. The FEM was employed to solve the nonlinear equation of motion because it can effortlessly handle the more complex geometries and boundary conditions. A doubly clamped CNT resonator actuated by distributed electrostatic force was the configuration subjected to the numerical experiments. Thermal effects upon the fundamental resonance behavior and the shift of resonance frequency due to attached mass, i.e., the mass detection sensitivity, were examined in environments of both high and low (or room) temperature. The fundamental resonance frequency increased with decreasing temperature in the high temperature environment, and increased with increasing temperature in the low temperature environment. The magnitude of the shift in resonance frequency caused by an attached mass represents the sensing performance of a mass sensor, i.e., its mass detection sensitivity, and it can be seen that this shift is affected by the temperature change and the amount of electrostatic force. The thermal effects on the mass detection sensitivity are intensified in the linear oscillation regime and increase with increasing CNT length; this intensification can either improve or worsen the detection sensitivity.

Application of the Moment Method in the Slip and Transition Regime for Microfluidic Flows

DTIC Science & Technology

2011-01-01

systems ( MEMS ), fluid flow at the micro- and nano-scale has received considerable attention [1]. A basic understanding of the nature of flow and heat ...Couette Flow Many MEMS devices contain oscillating parts where air (viscous) damping plays an important role. To understand the damping mechanisms...transfer in these devices is considered essential for efficient design and control of MEMS . Engineering applications for gas microflows include

Technologies for Fire and Damage Control and Condition Based Maintenance

DTIC Science & Technology

2011-12-01

sheathing, thermal and acoustic insulation, furnishing, bedding, mattresses, flooring , and wood fibre (paper and cardboard) and plastic packaging...Condition Based Maintenance”. The project objective was to develop an improved understanding of how materials, sensors and sensor systems choices impact the...ultraviolet spectral sensors and an acoustic sensor. The system also has data fusion software that analyses the sensor input and determines if the input

Flush Mounting Of Thin-Film Sensors

NASA Technical Reports Server (NTRS)

Moore, Thomas C., Sr.

1992-01-01

Technique developed for mounting thin-film sensors flush with surfaces like aerodynamic surfaces of aircraft, which often have compound curvatures. Sensor mounted in recess by use of vacuum pad and materials selected for specific application. Technique involves use of materials tailored to thermal properties of substrate in which sensor mounted. Together with customized materials, enables flush mounting of thin-film sensors in most situations in which recesses for sensors provided. Useful in both aircraft and automotive industries.

Differential multi-MOSFET nuclear radiation sensor

NASA Technical Reports Server (NTRS)

Deoliveira, W. A.

1977-01-01

Circuit allows minimization of thermal-drift errors, low power consumption, operation over wide dynamic range, improved sensitivity and stability with metaloxide-semiconductor field-effect transistor sensors.

In-vacuum sensors for the beamline components of the ITER neutral beam test facility.

PubMed

Dalla Palma, M; Pasqualotto, R; Sartori, E; Spagnolo, S; Spolaore, M; Veltri, P

2016-11-01

Embedded sensors have been designed for installation on the components of the MITICA beamline, the prototype ITER neutral beam injector (Megavolt ITER Injector and Concept Advancement), to derive characteristics of the particle beam and to monitor the component conditions during operation for protection and thermal control. Along the beamline, the components interacting with the particle beam are the neutralizer, the residual ion dump, and the calorimeter. The design and the positioning of sensors on each component have been developed considering the expected beam-surface interaction including non-ideal and off-normal conditions. The arrangement of the following instrumentation is presented: thermal sensors, strain gages, electrostatic probes including secondary emission detectors, grounding shunt for electrical currents, and accelerometers.

Thermal protection system ablation sensor

NASA Technical Reports Server (NTRS)

Gorbunov, Sergey (Inventor); Martinez, Edward R. (Inventor); Scott, James B. (Inventor); Oishi, Tomomi (Inventor); Fu, Johnny (Inventor); Mach, Joseph G. (Inventor); Santos, Jose B. (Inventor)

2011-01-01

An isotherm sensor tracks space vehicle temperatures by a thermal protection system (TPS) material during vehicle re-entry as a function of time, and surface recession through calibration, calculation, analysis and exposed surface modeling. Sensor design includes: two resistive conductors, wound around a tube, with a first end of each conductor connected to a constant current source, and second ends electrically insulated from each other by a selected material that becomes an electrically conductive char at higher temperatures to thereby complete an electrical circuit. The sensor conductors become shorter as ablation proceeds and reduced resistance in the completed electrical circuit (proportional to conductor length) is continually monitored, using measured end-to-end voltage change or current in the circuit. Thermocouple and/or piezoelectric measurements provide consistency checks on local temperatures.

Thermal microphotonic sensor and sensor array

DOEpatents

Watts, Michael R [Albuquerque, NM; Shaw, Michael J [Tijeras, NM; Nielson, Gregory N [Albuquerque, NM; Lentine, Anthony L [Albuquerque, NM

2010-02-23

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

Temperature-compensated strain measurement using fiber Bragg grating sensors embedded in composite laminates

NASA Astrophysics Data System (ADS)

Tanaka, Nobuhira; Okabe, Yoji; Takeda, Nobuo

2003-12-01

For accurate strain measurement by fiber Bragg grating (FBG) sensors, it is necessary to compensate the influence of temperature change. In this study two devices using FBG sensors have been developed for temperature-compensated strain measurement. They are named 'hybrid sensor' and 'laminate sensor', respectively. The former consists of two different materials connected in series: carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic. Each material contains an FBG sensor with a different Bragg wavelength, and both ends of the device are glued to a structure. Using the difference of their Young's moduli and coefficients of thermal expansion, both strain and temperature can be measured. The latter sensor is a laminate of two 90° plies of CFRP and an epoxy plate, and an FBG sensor is embedded in the epoxy plate. When the temperature changes, the cross section of the optical fiber is deformed by the thermal residual stress. The deformation of the fiber causes the birefringence and widens the reflection spectrum. Since the temperature can be calculated from the spectrum width, which changes in proportion to the temperature, the accuracy of the strain measurement is improved. The usefulness of these sensors was experimentally confirmed.

Temperature-compensated strain measurement using FBG sensors embedded in composite laminates

NASA Astrophysics Data System (ADS)

Tanaka, Nobuhira; Okabe, Yoji; Takeda, Nobuo

2002-07-01

For accurate strain measurement by fiber Bragg grating (FBG) sensors, it is necessary to compensate the influence of temperature change. In this study two devices using FBG sensors have been developed for temperature-compensated strain measurement. They are named hybrid sensor and laminate sensor, respectively. The former consists of two different materials connected in series: carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic (GFRP). Each material contains an FBG sensor with a different Bragg wavelength, and both ends of the device are glue to a structure. Using the difference of their Young's moduli and coefficients of thermal expansion (CTEs), both strain and temperature can be measured. The latter sensor is a laminate of two 90 degree(s) plies of CFRP and an epoxy plate, and an FBG sensor is embedded in the epoxy plate. When the temperature changes, the cross section of the optical fiber is deformed by the thermal residual stress. The deformation of the fiber causes the birefringence and widens the reflection spectrum. Since the temperature can be calculated from the spectrum width, which changes in proportion to the temperature, the accuracy of the strain measurement is improved. The usefulness of these sensors were experimentally confirmed.

Multi-parameter fibre Bragg grating sensor-array for thermal vacuum cycling test

NASA Astrophysics Data System (ADS)

Cheng, L.; Ahlers, B.; Toet, P.; Casarosa, G.; Appolloni, M.

2017-11-01

Fibre Bragg Grating (FBG) sensor systems based on optical fibres are gaining interest in space applications. Studies on Structural Health Monitoring (SHM) of the reusable launchers using FBG sensors have been carried out in the Future European Space Transportation Investigations Programme (FESTIP). Increasing investment in the development on FBG sensor applications is foreseen for the Future Launchers Preparatory Programme (FLPP). TNO has performed different SHM measurements with FBGs including on the VEGA interstage [1, 2] in 2006. Within the current project, a multi-parameter FBG sensor array demonstrator system for temperature and strain measurements is designed, fabricated and tested under ambient as well as Thermal Vacuum (TV) conditions in a TV chamber of the European Space Agency (ESA), ESTEC site. The aim is the development of a multi-parameters measuring system based on FBG technology for space applications. During the TV tests of a Space Craft (S/C) or its subsystems, thermal measurements, as well as strain measurements are needed by the engineers in order to verify their prediction and to validate their models. Because of the dimensions of the test specimen and the accuracy requested to the measurement, a large number of observation/measuring points are needed. Conventional sensor systems require a complex routing of the cables connecting the sensors to their acquisition unit. This will add extra weight to the construction under test. FBG sensors are potentially light-weight and can easily be multiplexed in an array configuration. The different tasks comply of a demonstrator system design; its component selection, procurement, manufacturing and finally its assembly. The temperature FBG sensor is calibrated in a dedicated laboratory setup down to liquid nitrogen (LN2) temperature at TNO. A temperature-wavelength calibration curve is generated. After a test programme definition a setup in thermal vacuum is realised at ESA premises including a mechanical strain transducer to generate strain via a dedicated feed through in the chamber. Thermocouples are used to log the temperature for comparison to the temperature FBG sensor. Extreme temperature ranges from -150°C and +70°C at a pressure down to 10-4 Pa (10-6 mbar) are covered as well as testing under ambient conditions. In total five thermal cycles during a week test are performed. The FBG temperature sensor test results performed in the ESA/ESTEC TV chamber reveal high reproducibility (within 1 °C) within the test temperature range without any evidence of hysteresis. Differences are detected to the previous calibration curve. Investigation is performed to find the cause of the discrepancy. Differences between the test set-ups are identified. Equipment of the TNO test is checked and excluded to be the cause. Additional experiments are performed. The discrepancy is most likely caused by a 'thermal shock' due to rapid cooling down to LN2 temperature, which results in a wavelength shift. Test data of the FBG strain sensor is analysed. The read-out of the FBG strain sensor varies with the temperature during the test. This can be caused by temperature induced changes in the mechanical setup (fastening of the mechanical parts) or impact of temperature to the mechanical strain transfer to the FBG. Improvements are identified and recommendations given for future activities.

Development of Position-Sensitive Magnetic Calorimeters for X-Ray Astronomy

NASA Technical Reports Server (NTRS)

Bandler, SImon; Stevenson, Thomas; Hsieh, Wen-Ting

2011-01-01

Metallic magnetic calorimeters (MMC) are one of the most promising devices to provide very high energy resolution needed for future astronomical x-ray spectroscopy. MMC detectors can be built to large detector arrays having thousands of pixels. Position-sensitive magnetic (PoSM) microcalorimeters consist of multiple absorbers thermally coupled to one magnetic micro calorimeter. Each absorber element has a different thermal coupling to the MMC, resulting in a distribution of different pulse shapes and enabling position discrimination between the absorber elements. PoSMs therefore achieve the large focal plane area with fewer number of readout channels without compromising spatial sampling. Excellent performance of PoSMs was achieved by optimizing the designs of key parameters such as the thermal conductance among the absorbers, magnetic sensor, and heat sink, as well as the absorber heat capacities. Micro fab ri - cation techniques were developed to construct four-absorber PoSMs, in which each absorber consists of a two-layer composite of bismuth and gold. The energy resolution (FWHM full width at half maximum) was measured to be better than 5 eV at 6 keV x-rays for all four absorbers. Position determination was demonstrated with pulse-shape discrimination, as well as with pulse rise time. X-ray microcalorimeters are usually designed to thermalize as quickly as possible to avoid degradation in energy resolution from position dependence to the pulse shapes. Each pixel consists of an absorber and a temperature sensor, both decoupled from the cold bath through a weak thermal link. Each pixel requires a separate readout channel; for instance, with a SQUID (superconducting quantum interference device). For future astronomy missions where thousands to millions of resolution elements are required, having an individual SQUID readout channel for each pixel becomes difficult. One route to attaining these goals is a position-sensitive detector in which a large continuous or pixilated array of x-ray absorbers shares fewer numbers of temperature sensors. A means of discriminating the signals from different absorber positions, however, needs to be built into the device for each sensor. The design concept for the device is such that the shape of the temperature pulse with time depends on the location of the absorber. This inherent position sensitivity of the signal is then analyzed to determine the location of the event precisely, effectively yielding one device with many sub-pixels. With such devices, the total number of electronic channels required to read out a given number of pixels is significantly reduced. PoSMs were developed that consist of four discrete absorbers connected to a single magnetic sensor. The design concept can be extended to more than four absorbers per sensor. The thermal conductance between the sensor and each absorber is different by design and consequently, the pulse shapes are different depending upon which absorber the xrays are received, allowing position discrimination. A magnetic sensor was used in which a paramagnetic Au:Er temperature-sensitive material is located in a weak magnetic field. Deposition of energy from an x-ray photon causes an increase in temperature, which leads to a change of magnetization of the paramagnetic sensor, which is subsequently read out using a low noise dc-SQUID. The PoSM microcalorimeters are fully microfabricated: the Au:Er sensor is located above the meander, with a thin insulation gap in between. For this position-sensitive device, four electroplated absorbers are thermally linked to the sensor via heat links of different thermal conductance. One pixel is identical to that of a single-pixel design, consisting of an overhanging absorber fabricated directly on top of the sensor. It is therefore very strongly thermally coupled to it. The three other absorbers are supported directly on a silicon-nitride membrane. These absorbers are thermally coupled to the sensor via Ti (5 nm)/Au250 nm) metal links. The strength of the links is parameterized by the number of gold squares making up the link. For detector performance, experimentally different pulse-shapes were demonstrated with 6 keV x-rays, which clearly show different rise times for different absorber positions. For energy resolution measurement, the PoSM was operated at 32 mK with an applied field that was generated using a persistent current of 50 mA. Over the four pixels, energy resolution ranges from 4.4 to 4.7 eV were demonstrated.

A IR-Femtosecond Laser Hybrid Sensor to Measure the Thermal Expansion and Thermo-Optical Coefficient of Silica-Based FBG at High Temperatures.

PubMed

Li, Litong; Lv, Dajuan; Yang, Minghong; Xiong, Liangming; Luo, Jie

2018-01-26

In this paper, a hybrid sensor was fabricated using a IR-femtosecond laser to measure the thermal expansion and thermo-optical coefficient of silica-based fiber Bragg gratings (FBGs). The hybrid sensor was composed of an inline fiber Fabry-Perot interferometer (FFPI) cavity and a type-II FBG. Experiment results showed that the type-II FBG had three high reflectivity resonances in the wavelength ranging from 1100 to 1600 nm, showing the peaks in 1.1, 1.3 and 1.5 μm, respectively. The thermal expansion and thermo-optical coefficient (1.3 μm, 1.5 μm) of silica-based FBG, under temperatures ranging from 30 to 1100 °C, had been simultaneously calculated by measuring the wavelength of the type-II FBG and FFPI cavity length.

Thermal bioaerosol cloud tracking with Bayesian classification

NASA Astrophysics Data System (ADS)

Smith, Christian W.; Dupuis, Julia R.; Schundler, Elizabeth C.; Marinelli, William J.

2017-05-01

The development of a wide area, bioaerosol early warning capability employing existing uncooled thermal imaging systems used for persistent perimeter surveillance is discussed. The capability exploits thermal imagers with other available data streams including meteorological data and employs a recursive Bayesian classifier to detect, track, and classify observed thermal objects with attributes consistent with a bioaerosol plume. Target detection is achieved based on similarity to a phenomenological model which predicts the scene-dependent thermal signature of bioaerosol plumes. Change detection in thermal sensor data is combined with local meteorological data to locate targets with the appropriate thermal characteristics. Target motion is tracked utilizing a Kalman filter and nearly constant velocity motion model for cloud state estimation. Track management is performed using a logic-based upkeep system, and data association is accomplished using a combinatorial optimization technique. Bioaerosol threat classification is determined using a recursive Bayesian classifier to quantify the threat probability of each tracked object. The classifier can accept additional inputs from visible imagers, acoustic sensors, and point biological sensors to improve classification confidence. This capability was successfully demonstrated for bioaerosol simulant releases during field testing at Dugway Proving Grounds. Standoff detection at a range of 700m was achieved for as little as 500g of anthrax simulant. Developmental test results will be reviewed for a range of simulant releases, and future development and transition plans for the bioaerosol early warning platform will be discussed.

Effect of perspiration on skin temperature measurements by infrared thermography and contact thermometry during aerobic cycling

NASA Astrophysics Data System (ADS)

Priego Quesada, Jose Ignacio; Martínez Guillamón, Natividad; Cibrián Ortiz de Anda, Rosa M.^a.; Psikuta, Agnes; Annaheim, Simon; Rossi, René Michel; Corberán Salvador, José Miguel; Pérez-Soriano, Pedro; Salvador Palmer, Rosario

2015-09-01

The aim of the present study was to compare infrared thermography and thermal contact sensors for measuring skin temperature during cycling in a moderate environment. Fourteen cyclists performed a 45-min cycling test at 50% of peak power output. Skin temperatures were simultaneously recorded by infrared thermography and thermal contact sensors before and immediately after cycling activity as well as after 10 min cooling-down, representing different skin wetness and blood perfusion states. Additionally, surface temperature during well controlled dry and wet heat exchange (avoiding thermoregulatory responses) using a hot plate system was assessed by infrared thermography and thermal contact sensors. In human trials, the inter-method correlation coefficient was high when measured before cycling (r = 0.92) whereas it was reduced immediately after the cycling (r = 0.82) and after the cooling-down phase (r = 0.59). Immediately after cycling, infrared thermography provided lower temperature values than thermal contact sensors whereas it presented higher temperatures after the cooling-down phase. Comparable results as in human trials were observed for hot plate tests in dry and wet states. Results support the application of infrared thermography for measuring skin temperature in exercise scenarios where perspiration does not form a water film.

Sensing sheet: the response of full-bridge strain sensors to thermal variations for detecting and characterizing cracks

NASA Astrophysics Data System (ADS)

Tung, S.-T.; Glisic, B.

2016-12-01

Sensing sheets based on large-area electronics consist of a dense array of unit strain sensors. This new technology has potential for becoming an effective and affordable monitoring tool that can identify, localize and quantify surface damage in structures. This research contributes to their development by investigating the response of full-bridge unit strain sensors to thermal variations. Overall, this investigation quantifies the effects of temperature on thin-film full-bridge strain sensors monitoring uncracked and cracked concrete. Additionally, an empirical formula is developed to estimate crack width given an observed strain change and a measured temperature change. This research led to the understanding of the behavior of full-bridge strain sensors installed on cracked concrete and exposed to temperature variations. It proves the concept of the sensing sheet and its suitability for application in environments with variable temperature.

Stretchable silicon nanoribbon electronics for skin prosthesis.

PubMed

Kim, Jaemin; Lee, Mincheol; Shim, Hyung Joon; Ghaffari, Roozbeh; Cho, Hye Rim; Son, Donghee; Jung, Yei Hwan; Soh, Min; Choi, Changsoon; Jung, Sungmook; Chu, Kon; Jeon, Daejong; Lee, Soon-Tae; Kim, Ji Hoon; Choi, Seung Hong; Hyeon, Taeghwan; Kim, Dae-Hyeong

2014-12-09

Sensory receptors in human skin transmit a wealth of tactile and thermal signals from external environments to the brain. Despite advances in our understanding of mechano- and thermosensation, replication of these unique sensory characteristics in artificial skin and prosthetics remains challenging. Recent efforts to develop smart prosthetics, which exploit rigid and/or semi-flexible pressure, strain and temperature sensors, provide promising routes for sensor-laden bionic systems, but with limited stretchability, detection range and spatio-temporal resolution. Here we demonstrate smart prosthetic skin instrumented with ultrathin, single crystalline silicon nanoribbon strain, pressure and temperature sensor arrays as well as associated humidity sensors, electroresistive heaters and stretchable multi-electrode arrays for nerve stimulation. This collection of stretchable sensors and actuators facilitate highly localized mechanical and thermal skin-like perception in response to external stimuli, thus providing unique opportunities for emerging classes of prostheses and peripheral nervous system interface technologies.

Airborne Optical and Thermal Remote Sensing for Wildfire Detection and Monitoring.

PubMed

Allison, Robert S; Johnston, Joshua M; Craig, Gregory; Jennings, Sion

2016-08-18

For decades detection and monitoring of forest and other wildland fires has relied heavily on aircraft (and satellites). Technical advances and improved affordability of both sensors and sensor platforms promise to revolutionize the way aircraft detect, monitor and help suppress wildfires. Sensor systems like hyperspectral cameras, image intensifiers and thermal cameras that have previously been limited in use due to cost or technology considerations are now becoming widely available and affordable. Similarly, new airborne sensor platforms, particularly small, unmanned aircraft or drones, are enabling new applications for airborne fire sensing. In this review we outline the state of the art in direct, semi-automated and automated fire detection from both manned and unmanned aerial platforms. We discuss the operational constraints and opportunities provided by these sensor systems including a discussion of the objective evaluation of these systems in a realistic context.

On the Use of a Low-Cost Thermal Sensor to Improve Kinect People Detection in a Mobile Robot

PubMed Central

Susperregi, Loreto; Sierra, Basilio; Castrillón, Modesto; Lorenzo, Javier; Martínez-Otzeta, Jose María; Lazkano, Elena

2013-01-01

Detecting people is a key capability for robots that operate in populated environments. In this paper, we have adopted a hierarchical approach that combines classifiers created using supervised learning in order to identify whether a person is in the view-scope of the robot or not. Our approach makes use of vision, depth and thermal sensors mounted on top of a mobile platform. The set of sensors is set up combining the rich data source offered by a Kinect sensor, which provides vision and depth at low cost, and a thermopile array sensor. Experimental results carried out with a mobile platform in a manufacturing shop floor and in a science museum have shown that the false positive rate achieved using any single cue is drastically reduced. The performance of our algorithm improves other well-known approaches, such as C4 and histogram of oriented gradients (HOG). PMID:24172285

Solvent-free fabrication of biodegradable hot-film flow sensor for noninvasive respiratory monitoring

NASA Astrophysics Data System (ADS)

Dinh, Toan; Phan, Hoang-Phuong; Nguyen, Tuan-Khoa; Qamar, Afzaal; Woodfield, Peter; Zhu, Yong; Nguyen, Nam-Trung; Viet Dao, Dzung

2017-06-01

In this paper, we report on a low-cost, environment-friendly and wearable thermal flow sensor, which can be manufactured in-house using pencil graphite as a sensing hot film and biodegradable printing paper as a substrate, without using any toxic solvents or cleanroom facilities. The hot film flow sensor offers excellent performance such as high signal-to-noise ratio (≥slant 40 for an air flow velocity of 1 m s-1), high sensitivity to airflow (53.7 mV(m s-1)-0.8) and outstanding long-term stability (almost no drift in 24 h). The sensor can be comfortably affixed to the philtrum of patients and measures human respiration in realtime. The results indicate that the wearable thermal flow sensors fabricated by this solvent-free and user-friendly method could be employed in human respiratory monitoring.

Airborne Optical and Thermal Remote Sensing for Wildfire Detection and Monitoring

PubMed Central

Allison, Robert S.; Johnston, Joshua M.; Craig, Gregory; Jennings, Sion

2016-01-01

For decades detection and monitoring of forest and other wildland fires has relied heavily on aircraft (and satellites). Technical advances and improved affordability of both sensors and sensor platforms promise to revolutionize the way aircraft detect, monitor and help suppress wildfires. Sensor systems like hyperspectral cameras, image intensifiers and thermal cameras that have previously been limited in use due to cost or technology considerations are now becoming widely available and affordable. Similarly, new airborne sensor platforms, particularly small, unmanned aircraft or drones, are enabling new applications for airborne fire sensing. In this review we outline the state of the art in direct, semi-automated and automated fire detection from both manned and unmanned aerial platforms. We discuss the operational constraints and opportunities provided by these sensor systems including a discussion of the objective evaluation of these systems in a realistic context. PMID:27548174

Effect of α-stable sorptive waiting times on microbial transport in microflow cells

NASA Astrophysics Data System (ADS)

Bonilla, F. Alejandro; Cushman, John H.

2002-09-01

The interaction of bacteria in the fluid phase with pore walls of a porous material involves a wide range of effective reaction times which obey a diversity of substrate-bacteria adhesion conditions, and adhesive mechanisms. For a transported species, this heterogeneity in sorption conditions occurs both in time and space. Modern experimental methods allow one to measure adhesive reaction times of individual bacteria. This detailed information may be incorporated into nonequilibrium transport-sorption models that capture the heterogeneity in reaction times caused by varying chemical conditions. We have carried out particle (Brownian dynamic) simulations of adhesive, self-motile bacteria convected between two infinite plates as a model for a microflow cell. The adhesive heterogeneity is included by introducing adhesive reaction time (understood as time spent at a solid boundary once the particle collides against it) as a random variable that can be infinite (irreversible sorption) or vary over a wide range of values. This is made possible by treating this reaction time random variable as having an α-stable probability distribution whose properties (e.g., infinite moments and long tails) are distinctive from the standard exponential distribution commonly used to model reversible sorption. In addition, the α-stable distribution is renormalizable and hence upscalable to complex porous media. Simulations are performed in a pressure-driven microflow cell. Bacteria motility (driven by an effective Brownian force) acts as a dispersive component in the convective field. Upon collision with the pore wall, bacteria attachment or detachment occurs. The time bacteria spend at the wall varies over a wide range of time scales. This model has the advantage of being parsimonious, that is, involving very few parameters to model complex irreversible or reversible adhesion in heterogeneous environments. It is shown that, as in Taylor dispersion, the ratio of the channel half width b to the Brownian bacteria motility coefficient (D0 or dispersion coefficient) tb=b2/D0 controls the different adhesion regimes along with the value of α. Universal scalings (with respect to dimensionless time t*=t/tb) for the mean position, =V*efftθ*, and mean-square displacement, <ΔX2>=D*efftγ* exist for long-time dispersion and the coefficients were obtained. The model can account for a great many sorptive processes including reversible and irreversible sorption, and sub- and superdispersive regimes with just a few parameters.

Luminescent Sensors for Tracking Spatial Particle Distribution in an Explosion

NASA Astrophysics Data System (ADS)

Eilers, Hergen; Gunawidjaja, Ray; Diez-Y-Riega, Helena; Svingala, Forrest; Daniels, Amber; Lightstone, James; Washington State University Collaboration; Nswc Iheodtd Collaboration

2015-06-01

We previously developed and tested thermally sensitive particles that, when seeded into an explosive event, flow with the expanding post-detonation fireball and provide ex-situ measurements of this thermal environment. This current work presents the development and testing of tracking particles that are used in concert with the thermally sensitive particles to encode the initial positions of materials recovered for ex-situ analysis. These tracking sensors consist of fully-crystallized (c) rare-earth-doped yttria particles such as c-Dy:Y2O3, c-Sm:Y2O3, and c-Er,Yb:Y2O3. The temperature sensors consist of mixtures of precursor (p) and fully crystallized materials such as p-Eu:Y2O3/c-Tb:Y2O3 orp-Eu:ZrO2/c-Tb:Y2O3. Three mixtures containing one of the tracking sensors and one of the temperature sensing mixtures are placed at different locations within the chamber. Post-detonation, the tracking particles in the debris are excited by 365 nm light, resulting in different color luminescence, and allowing for potential visual inspection of the particle distribution originating from the different locations. Meanwhile, the temperature is determined from spectral changes of the precursor sensor materials or by comparison of the precursor sensor materials with the Tb:Y2O3 intensity reference. Defense Threat Reduction Agency, HDTRA1-10-1-0005.

Human Location Detection System Using Micro-Electromechanical Sensor for Intelligent Fan

NASA Astrophysics Data System (ADS)

Parnin, S.; Rahman, M. M.

2017-03-01

This paper presented the development of sensory system for detection of both the presence and the location of human in a room spaces using MEMS Thermal sensor. The system is able to detect the surface temperature of occupants by a non-contact detection at the maximum of 6 meters far. It can be integrated to any swing type of electrical appliances such as standing fan or a similar devices. Differentiating human from other moving and or static object by heat variable is nearly impossible since human, animals and electrical appliances produce heat. The uncontrollable heat properties which can change and transfer will add to the detection issue. Integrating the low cost MEMS based thermal sensor can solve the first of human sensing problem by its ability to detect human in stationary. Further discrimination and analysis must therefore be made to the measured temperature data to distinguish human from other objects. In this project, the fan is properly designed and program in such a way that it can adapt to different events starting from the human sensing stage to its dynamic and mechanical moving parts. Up to this stage initial testing to the Omron D6T microelectromechanical thermal sensor is currently under several experimental stages. Experimental result of the sensor tested on stationary and motion state of human are behaviorally differentiable and successfully locate the human position by detecting the maximum temperature of each sensor reading.

Thermal infrared reference sources fabricated from low-cost components and materials

NASA Astrophysics Data System (ADS)

Hovland, Harald; Skauli, Torbjørn

2018-04-01

Mass markets, including mobile phones and automotive sensors, drive rapid developments of imaging technologies toward high performance, low cost sensors, even for the thermal infrared. Good infrared calibration blackbody sources have remained relatively costly, however. Here we demonstrate how to make low-cost reference sources, making quantitative infrared radiometry more accessible to a wider community. Our approach uses ordinary construction materials combined with low cost microcontrollers, digital temperature sensors and foil heater elements from massmarket 3D printers. Blackbodies are constructed from a foil heater of some chosen size and shape, attached to the back of a similarly shaped aluminum plate coated with commercial black paint, which normally exhibits high emissivity. The emissivity can be readily checked by using a thermal imager to view the reflection of a hot object. A digital temperature sensor is attached to the back of the plate. Thermal isolation of the backside minimizes temperature gradients through the plate, ensuring correct readings of the front temperature. The isolation also serves to minimize convection gradients and keeps power consumption low, which is useful for battery powered operation in the field. We demonstrate surface blackbodies (200x200 mm2) with surface homogeneities as low as 0.1°C at 100°C. Homogeneous heating and low thermal mass provides for fast settling time and setup/pack-down time. The approach is scalable to larger sizes by tiling, enabling portable and foldable square-meter-size or larger devices.

Multivariable control of a rapid thermal processor using ultrasonic sensors

NASA Astrophysics Data System (ADS)

Dankoski, Paul C. P.

The semiconductor manufacturing industry faces the need for tighter control of thermal budget and process variations as circuit feature sizes decrease. Strategies to meet this need include supervisory control, run-to-run control, and real-time feedback control. Typically, the level of control chosen depends upon the actuation and sensing available. Rapid Thermal Processing (RTP) is one step of the manufacturing cycle requiring precise temperature control and hence real-time feedback control. At the outset of this research, the primary ingredient lacking from in-situ RTP temperature control was a suitable sensor. This research looks at an alternative to the traditional approach of pyrometry, which is limited by the unknown and possibly time-varying wafer emissivity. The technique is based upon the temperature dependence of the propagation time of an acoustic wave in the wafer. The aim of this thesis is to evaluate the ultrasonic sensors as a potentially viable sensor for control in RTP. To do this, an experimental implementation was developed at the Center for Integrated Systems. Because of the difficulty in applying a known temperature standard in an RTP environment, calibration to absolute temperature is nontrivial. Given reference propagation delays, multivariable model-based feedback control is applied to the system. The modelling and implementation details are described. The control techniques have been applied to a number of research processes including rapid thermal annealing and rapid thermal crystallization of thin silicon films on quartz/glass substrates.

Fiber optic distributed temperature sensor mapping of a jet-mixing flow field

DOE PAGES

Lomperski, Stephen; Gerardi, Craig; Pointer, William David

2015-03-04

In this paper, we introduce the use of a Rayleigh backscatter-based distributed fiber optic sensor to map the temperature field in air flow for a thermal fatigue application. The experiment involves a pair of air jets at 22 and 70°C discharging from 136 mm hexagonal channels into a 1 × 1 × 1.7 m tank at atmospheric pressure. A 40 m-long, Φ155 µm fiber optic sensor was wound back and forth across the tank midplane to form 16 horizontal measurement sections with a vertical spacing of 51 mm. This configuration generated a 2D temperature map with 2800 data points overmore » a 0.76 × 1.7 m plane. Fiber optic sensor readings were combined with PIV and infrared measurements to relate flow field characteristics to the thermal signature of the tank lid. The paper includes sensor stability data and notes issues encountered using the distributed temperature sensor in a flow field. In conclusion, sensors are sensitive to strain and humidity, and so accuracy relies upon strict control of both.« less

Optical fiber bundle displacement sensor using an ac-modulated light source with subnanometer resolution and low thermal drift

NASA Astrophysics Data System (ADS)

Shimamoto, Atsushi; Tanaka, Kohichi

1995-09-01

An optical fiber bundle displacement sensor with subnanometer order resolution and low thermal drift is proposed. The setup is based on a carrier amplifier system and involves techniques to eliminate fluctuation in the light power of the source. The achieved noise level of the sensor was 0.03 nm/ \\radical Hz \\end-radical . The stability was estimated by comparing the outputs of two different sensors from the same target for 4 ks (67 min). The relative displacements between the fiber bundle ends of the two sensors and the target surface varied in the area of 400 nm depending on the ambient temperature variation at 2 deg C. However, the difference in output between the two sensor systems is within 2 nm for more than 1 hour of measurement. It is expected that it would be reduced to within the area of 0.1 nm if the ambient temperature were controlled to within +/-0.1 deg C. It is concluded that the stability of the sensors is sufficiently good to be used with nanotechnological instruments.

Fiber optic distributed temperature sensor mapping of a jet-mixing flow field

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

Lomperski, Stephen; Gerardi, Craig; Pointer, William David

In this paper, we introduce the use of a Rayleigh backscatter-based distributed fiber optic sensor to map the temperature field in air flow for a thermal fatigue application. The experiment involves a pair of air jets at 22 and 70°C discharging from 136 mm hexagonal channels into a 1 × 1 × 1.7 m tank at atmospheric pressure. A 40 m-long, Φ155 µm fiber optic sensor was wound back and forth across the tank midplane to form 16 horizontal measurement sections with a vertical spacing of 51 mm. This configuration generated a 2D temperature map with 2800 data points overmore » a 0.76 × 1.7 m plane. Fiber optic sensor readings were combined with PIV and infrared measurements to relate flow field characteristics to the thermal signature of the tank lid. The paper includes sensor stability data and notes issues encountered using the distributed temperature sensor in a flow field. In conclusion, sensors are sensitive to strain and humidity, and so accuracy relies upon strict control of both.« less

Improvements to a Flow Sensor for Liquid Bismuth-Fed Hall Thrusters

NASA Technical Reports Server (NTRS)

Bonds, Kevin; Polzin, Kurt A.

2010-01-01

Recently, there has been significant interest in using bismuth metal as a propellant in Hall Thrusters [1, 2]. Bismuth offers some considerable cost, weight, and space savings over the traditional propellant--xenon. Quantifying the performance of liquid metal-fed Hall thrusters requires a very precise measure of the low propellant flow rates [1, 2]. The low flow rates (10 mg/sec) and the temperature at which free flowing liquid bismuth exists (above 300 C) preclude the use of off-the-shelf flow sensing equipment [3]. Therefore a new type of sensor is required. The hotspot bismuth flow sensor, described in Refs. [1-5] is designed to perform a flow rate measurement by measuring the velocity at which a thermal feature moves through a flow chamber. The mass flow rate can be determined from the time of flight of the thermal peak, [4, 5]. Previous research and testing has been concerned mainly with the generation of the thermal peak and it's subsequent detection. In this paper, we present design improvements to the sensor concept; and the results of testing conducted to verify the functionality of these improvements. A ceramic material is required for the sensor body (see Fig. 1), which must allow for active heating of the bismuth flow channel to keep the propellant in a liquid state. The material must be compatible with bismuth and must be bonded to conductive elements to allow for conduction of current into the liquid metal and measurement of the temperature in the flow. The new sensor requires fabrication techniques that will allow for a very small diameter flow chamber, which is required to produce useful measurements. Testing of various materials has revealed several that are potentially compatible with liquid bismuth. Of primary concern in the fabrication and testing of a robust, working prototype, is the compatibility of the selected materials with one another. Specifically, the thermal expansion rates of the materials relative to the ceramic body cannot expand so much as to cause cracks in the body or cause the bond between parts to delaminate. Those parts that will carry the current pulse must be electrically conductive while the sensor body must be an electrical insulator. Generally, the material choices as well as the sensor design must aid to preserve the integrity of the thermal feature to obtain accurate measurements. The present aim is to also incorporate, into the sensor body, an active heating arrangement based on ceramic heater technology similar to that used in semiconductor manufacturing.

Smart Building: Decision Making Architecture for Thermal Energy Management

PubMed Central

Hernández Uribe, Oscar; San Martin, Juan Pablo; Garcia-Alegre, María C.; Santos, Matilde; Guinea, Domingo

2015-01-01

Smart applications of the Internet of Things are improving the performance of buildings, reducing energy demand. Local and smart networks, soft computing methodologies, machine intelligence algorithms and pervasive sensors are some of the basics of energy optimization strategies developed for the benefit of environmental sustainability and user comfort. This work presents a distributed sensor-processor-communication decision-making architecture to improve the acquisition, storage and transfer of thermal energy in buildings. The developed system is implemented in a near Zero-Energy Building (nZEB) prototype equipped with a built-in thermal solar collector, where optical properties are analysed; a low enthalpy geothermal accumulation system, segmented in different temperature zones; and an envelope that includes a dynamic thermal barrier. An intelligent control of this dynamic thermal barrier is applied to reduce the thermal energy demand (heating and cooling) caused by daily and seasonal weather variations. Simulations and experimental results are presented to highlight the nZEB thermal energy reduction. PMID:26528978

Generation of Monodisperse Liquid Droplets in a Microfluidic Chip Using a High-Speed Gaseous Microflow

NASA Astrophysics Data System (ADS)

Tirandazi, Pooyan; Hidrovo, Carlos

2015-11-01

Over the last few years, microfluidic systems known as Lab-on-a-Chip (LOC) and micro total analysis systems (μTAS) have been increasingly developed as essential components for numerous biochemical applications. Droplet microfluidics, however, provides a distinctive attribute for delivering and processing discrete as well as ultrasmall volumes of fluid, which make droplet-based systems more beneficial over their continuous-phase counterparts. Droplet generation in its conventional scheme usually incorporates the injection of a liquid (water) into a continuous immiscible liquid (oil) medium. In this study we demonstrate a novel scheme for controlled generation of monodisperse droplets in confined gas-liquid microflows. We experimentally investigate the manipulation of water droplets in flow-focusing configurations using a high inertial air stream. Different flow regimes are observed by varying the gas and liquid flow rates, among which, the ``dripping regime'' where monodisperse droplets are generated is of great importance. The controlled size and generation rate of droplets in this region provide the capability for precise and contaminant-free delivery of microliter to nanoliter volumes of fluid. Furthermore, the high speed droplets generated in this method represent the basis for a new approach based on droplet pair collisions for fast efficient micromixing which provides a significant development in modern LOC and μTAS devices. This project is currently being supported by an NSF CAREER Award grant CBET-1151091.

Nature-Inspired Na2Ti3O7 Nanosheets-Formed Three-Dimensional Microflowers Architecture as a High-Performance Anode Material for Rechargeable Sodium-Ion Batteries.

PubMed

Anwer, Shoaib; Huang, Yongxin; Liu, Jia; Liu, Jiajia; Xu, Meng; Wang, Ziheng; Chen, Renjie; Zhang, Jiatao; Wu, Feng

2017-04-05

Low cycling stability and poor rate performance are two of the distinctive drawbacks of most electrode materials for sodium-ion batteries (SIBs). Here, inspired by natural flower structures, we take advantage of the three-dimensional (3D) hierarchical flower-like stable microstructures formed by two-dimensional (2D) nanosheets to solve these problems. By precise control of the hydrothermal synthesis conditions, a novel three-dimensional (3D) flower-like architecture consisting of 2D Na 2 Ti 3 O 7 nanosheets (Na-TNSs) has been successfully synthesized. The arbitrarily arranged but closely interlinked thin nanosheets in carnation-shaped 3D Na 2 Ti 3 O 7 microflowers (Na-TMFs) originate a good network of electrically conductive paths in an electrode. Thus, Na-TMFs can get electrons from all directions and be fully utilized for sodium-ion insertion and extraction reactions, which can improve sodium storage properties with enhanced rate capability and super cycling performance. Furthermore, the large specific surface area provides a high capacity, which can be ascribed to the pseudo-capacitance effect. The wettability of the electrolyte was also improved by the porous and crumpled structure. The remarkably improved cycling performance and rate capability of Na-TMFs make a captivating case for its development as an advanced anode material for SIBs.

Multi-sensor fusion of Landsat 8 thermal infrared (TIR) and panchromatic (PAN) images.

PubMed

Jung, Hyung-Sup; Park, Sung-Whan

2014-12-18

Data fusion is defined as the combination of data from multiple sensors such that the resulting information is better than would be possible when the sensors are used individually. The multi-sensor fusion of panchromatic (PAN) and thermal infrared (TIR) images is a good example of this data fusion. While a PAN image has higher spatial resolution, a TIR one has lower spatial resolution. In this study, we have proposed an efficient method to fuse Landsat 8 PAN and TIR images using an optimal scaling factor in order to control the trade-off between the spatial details and the thermal information. We have compared the fused images created from different scaling factors and then tested the performance of the proposed method at urban and rural test areas. The test results show that the proposed method merges the spatial resolution of PAN image and the temperature information of TIR image efficiently. The proposed method may be applied to detect lava flows of volcanic activity, radioactive exposure of nuclear power plants, and surface temperature change with respect to land-use change.

Thermal and chemical treatment of polymer optical fiber Bragg grating sensors for enhanced mechanical sensitivity

NASA Astrophysics Data System (ADS)

Pospori, A.; Marques, C. A. F.; Sáez-Rodríguez, D.; Nielsen, K.; Bang, O.; Webb, D. J.

2017-07-01

An investigation of the thermal annealing effects on the strain, stress, and force sensitivities of polymer optical fiber Bragg grating sensors is performed. We demonstrate for the first time that the fiber annealing can enhance both stress and force sensitivities of Bragg grating sensors, with the possible cause being the molecular relaxation of the polymer when fiber is raised above the β -transition temperature. A simple, cost-effective, but well controlled method for fiber annealing is also presented in this work. In addition, the effects of chemical etching on the strain, stress, and force sensitivities have been investigated. Results show that fiber etching too can increase the force sensitivity, and it can also affect the strain and stress sensitivities of the Bragg grating sensors.

In-vacuum sensors for the beamline components of the ITER neutral beam test facility

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

Dalla Palma, M., E-mail: mauro.dallapalma@igi.cnr.it; Pasqualotto, R.; Spagnolo, S.

2016-11-15

Embedded sensors have been designed for installation on the components of the MITICA beamline, the prototype ITER neutral beam injector (Megavolt ITER Injector and Concept Advancement), to derive characteristics of the particle beam and to monitor the component conditions during operation for protection and thermal control. Along the beamline, the components interacting with the particle beam are the neutralizer, the residual ion dump, and the calorimeter. The design and the positioning of sensors on each component have been developed considering the expected beam-surface interaction including non-ideal and off-normal conditions. The arrangement of the following instrumentation is presented: thermal sensors, strainmore » gages, electrostatic probes including secondary emission detectors, grounding shunt for electrical currents, and accelerometers.« less

Analysis of continuous multi-seasonal in-situ subsurface temperature measurements on Mars

NASA Astrophysics Data System (ADS)

Paton, M. D.; Harri, A.-M.; Mäkinen, T.; Savijärvi, H.; Kemppinen, O.; Hagermann, A.

2015-10-01

Our investigations reveal the local thermal properties on the Martian surface at the Viking Lander 1 (VL-1) site. We achieved this by using the VL-1 footpad temperature sensor which was buried, and due to its location, was under shadow for extensive periods of time during each sol. Reconstruction of the surface and subsurface temperature history of the regolith in the vicinity of the temperature sensor was made using a 1-D atmospheric column model (UH-FMI) together with a thermal model of the lander. The results have implications for the interpretation of subsurface thermal measurements made close to a spacecraft or rock, interpretation of remote sensing measurements of thermal inertia and understanding the micro-scale behavior of the Martian atmosphere.

Cooperative implementation of a high temperature acoustic sensor

NASA Technical Reports Server (NTRS)

Baldini, S. E.; Nowakowski, Edward; Smith, Herbert G.; Friebele, E. J.; Putnam, Martin A.; Rogowski, Robert; Melvin, Leland D.; Claus, Richard O.; Tran, Tuan; Holben, Milford S., Jr.

1991-01-01

The current status and results of a cooperative program aimed at the implementation of a high-temperature acoustic/strain sensor onto metallic structures are reported. The sensor systems that are to be implemented under this program will measure thermal expansion, maneuver loads, aircraft buffet, sonic fatigue, and acoustic emissions in environments that approach 1800 F. The discussion covers fiber development, fabrication of an extrinsic Fabry-Perot interferometer acoustic sensor, sensor mounting/integration, and results of an evaluation of the sensor capabilities.

SENSOR++: Simulation of Remote Sensing Systems from Visible to Thermal Infrared

NASA Astrophysics Data System (ADS)

Paproth, C.; Schlüßler, E.; Scherbaum, P.; Börner, A.

2012-07-01

During the development process of a remote sensing system, the optimization and the verification of the sensor system are important tasks. To support these tasks, the simulation of the sensor and its output is valuable. This enables the developers to test algorithms, estimate errors, and evaluate the capabilities of the whole sensor system before the final remote sensing system is available and produces real data. The presented simulation concept, SENSOR++, consists of three parts. The first part is the geometric simulation which calculates where the sensor looks at by using a ray tracing algorithm. This also determines whether the observed part of the scene is shadowed or not. The second part describes the radiometry and results in the spectral at-sensor radiance from the visible spectrum to the thermal infrared according to the simulated sensor type. In the case of earth remote sensing, it also includes a model of the radiative transfer through the atmosphere. The final part uses the at-sensor radiance to generate digital images by using an optical and an electronic sensor model. Using SENSOR++ for an optimization requires the additional application of task-specific data processing algorithms. The principle of the simulation approach is explained, all relevant concepts of SENSOR++ are discussed, and first examples of its use are given, for example a camera simulation for a moon lander. Finally, the verification of SENSOR++ is demonstrated.

Fiber Optic Thermal Detection of Composite Delaminations

NASA Technical Reports Server (NTRS)

Wu, Meng-Chou; Winfree, William P.

2011-01-01

A recently developed technique is presented for thermographic detection of delaminations in composites by performing temperature measurements with fiber optic Bragg gratings. A single optical fiber with multiple Bragg gratings employed as surface temperature sensors was bonded to the surface of a composite with subsurface defects. The investigated structure was a 10-ply composite specimen with prefabricated delaminations of various sizes and depths. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The data obtained from grating sensors were analyzed with thermal modeling techniques of conventional thermography to reveal particular characteristics of the interested areas. Results were compared and found to be consistent with the calculations using numerical simulation techniques. Also discussed are methods including various heating sources and patterns, and their limitations for performing in-situ structural health monitoring.

Theoretical analysis of microring resonator-based biosensor with high resolution and free of temperature influence

NASA Astrophysics Data System (ADS)

Jian, Aoqun; Zou, Lu; Tang, Haiquan; Duan, Qianqian; Ji, Jianlong; Zhang, Qianwu; Zhang, Xuming; Sang, Shengbo

2017-06-01

The issue of thermal effects is inevitable for the ultrahigh refractive index (RI) measurement. A biosensor with parallel-coupled dual-microring resonator configuration is proposed to achieve high resolution and free thermal effects measurement. Based on the coupled-resonator-induced transparency effect, the design and principle of the biosensor are introduced in detail, and the performance of the sensor is deduced by simulations. Compared to the biosensor based on a single-ring configuration, the designed biosensor has a 10-fold increased Q value according to the simulation results, thus the sensor is expected to achieve a particularly high resolution. In addition, the output signal of the mathematical model of the proposed sensor can eliminate the thermal influence by adopting an algorithm. This work is expected to have great application potentials in the areas of high-resolution RI measurement, such as biomedical discoveries, virus screening, and drinking water safety.

Fiber Optic Thermal Health Monitoring of Aerospace Structures and Materials

NASA Technical Reports Server (NTRS)

Wu, Meng-Chou; Winfree, William P.; Allison, Sidney G.

2009-01-01

A new technique is presented for thermographic detection of flaws in materials and structures by performing temperature measurements with fiber Bragg gratings. Individual optical fibers with multiple Bragg gratings employed as surface temperature sensors were bonded to the surfaces of structures with subsurface defects or thickness variations. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The investigated structures included a 10-ply composite specimen with subsurface delaminations of various sizes and depths. The data obtained from grating sensors were further analyzed with thermal modeling to reveal particular characteristics of the interested areas. These results were found to be consistent with those from conventional thermography techniques. Limitations of the technique were investigated using both experimental and numerical simulation techniques. Methods for performing in-situ structural health monitoring are discussed.

Transition-edge sensor with enhanced electrothermal feedback for cryogenic particle detection

DOEpatents

Nam, Sae Woo; Cabrera, Blas

2001-01-01

A superconducting transition-edge sensor with an electrothermal-feedback circuit, a heat sink thermally coupled thereto, a bias-feedback circuit electrically coupled with the electrothermal feedback circuit, and a current sensor electrically coupled with the bias-feedback circuit and inductively coupled with the electrothermal-feedback circuit.

Novel Air Flow Meter for an Automobile Engine Using a Si Sensor with Porous Si Thermal Isolation

PubMed Central

Hourdakis, Emmanouel; Sarafis, Panagiotis; Nassiopoulou, Androula G.

2012-01-01

An air flow meter for measuring the intake air of an automobile engine is presented. It is based on a miniaturized silicon thermal mass flow sensor using a thick porous Si (Po-Si) layer for local thermal isolation from the Si substrate, on which the sensor active elements are integrated. The sensor is mounted on one side of a printed circuit board (PCB), on the other side of which the readout and control electronics of the meter are mounted. The PCB is fixed on a housing containing a semi-cylindrical flow tube, in the middle of which the sensor is situated. An important advantage of the present air flow meter is that it detects with equal sensitivity both forward and reverse flows. Two prototypes were fabricated, a laboratory prototype for flow calibration using mass flow controllers and a final demonstrator with the housing mounted in an automobile engine inlet tube. The final demonstrator was tested in real life conditions in the engine inlet tube of a truck. It shows an almost linear response in a large flow range between –6,500 kg/h and +6,500 kg/h, which is an order of magnitude larger than the ones usually encountered in an automobile engine. PMID:23202189

Automatic panoramic thermal integrated sensor

NASA Astrophysics Data System (ADS)

Gutin, Mikhail A.; Tsui, Eddy K.; Gutin, Olga N.

2005-05-01

Historically, the US Army has recognized the advantages of panoramic imagers with high image resolution: increased area coverage with fewer cameras, instantaneous full horizon detection, location and tracking of multiple targets simultaneously, extended range, and others. The novel ViperViewTM high-resolution panoramic thermal imager is the heart of the Automatic Panoramic Thermal Integrated Sensor (APTIS), being jointly developed by Applied Science Innovative, Inc. (ASI) and the Armament Research, Development and Engineering Center (ARDEC) in support of the Future Combat Systems (FCS) and the Intelligent Munitions Systems (IMS). The APTIS is anticipated to operate as an intelligent node in a wireless network of multifunctional nodes that work together to improve situational awareness (SA) in many defense and offensive operations, as well as serve as a sensor node in tactical Intelligence Surveillance Reconnaissance (ISR). The ViperView is as an aberration-corrected omnidirectional imager with small optics designed to match the resolution of a 640x480 pixels IR camera with improved image quality for longer range target detection, classification, and tracking. The same approach is applicable to panoramic cameras working in the visible spectral range. Other components of the ATPIS sensor suite include ancillary sensors, advanced power management, and wakeup capability. This paper describes the development status of the APTIS system.

Novel air flow meter for an automobile engine using a Si sensor with porous Si thermal isolation.

PubMed

Hourdakis, Emmanouel; Sarafis, Panagiotis; Nassiopoulou, Androula G

2012-11-02

An air flow meter for measuring the intake air of an automobile engine is presented. It is based on a miniaturized silicon thermal mass flow sensor using a thick porous Si (Po-Si) layer for local thermal isolation from the Si substrate, on which the sensor active elements are integrated. The sensor is mounted on one side of a printed circuit board (PCB), on the other side of which the readout and control electronics of the meter are mounted. The PCB is fixed on a housing containing a semi-cylindrical flow tube, in the middle of which the sensor is situated. An important advantage of the present air flow meter is that it detects with equal sensitivity both forward and reverse flows. Two prototypes were fabricated, a laboratory prototype for flow calibration using mass flow controllers and a final demonstrator with the housing mounted in an automobile engine inlet tube. The final demonstrator was tested in real life conditions in the engine inlet tube of a truck. It shows an almost linear response in a large flow range between –6,500 kg/h and +6,500 kg/h, which is an order of magnitude larger than the ones usually encountered in an automobile engine.

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

PubMed Central

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

2017-01-01

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. PMID:28368344

Improved thermal neutron activation sensor for detection of bulk explosives

NASA Astrophysics Data System (ADS)

McFee, John E.; Faust, Anthony A.; Andrews, H. Robert; Clifford, Edward T. H.; Mosquera, Cristian M.

2012-06-01

Defence R&D Canada - Suffield and Bubble Technology Industries have been developing thermal neutron activation (TNA) sensors for detection of buried bulk explosives since 1994. First generation sensors, employing an isotopic source and NaI(Tl) gamma ray detectors, were deployed by Canadian Forces in 2002 as confirmation sensors on the ILDS teleoperated, vehicle-mounted, multi-sensor anti-tank landmine detection systems. The first generation TNA could detect anti-tank mines buried 10 cm or less in no more than a minute, but deeper mines and those significantly displaced horizontally required considerably longer times. Mines as deep as 30 cm could be detected with long counting times (1000 s). The second generation TNA detector is being developed with a number of improvements aimed at increasing sensitivity and facilitating ease of operation. Among these are an electronic neutron generator to increase sensitivity for deeper and horizontally displaced explosives; LaBr3(Ce) scintillators, to improve time response and energy resolution; improved thermal and electronic stability; improved sensor head geometry to minimize spatial response nonuniformity; and more robust data processing. This improved sensitivity can translate to either decreased counting times, decreased minimum detectable explosive quantities, increased maximum sensor-to-target displacement, or a trade off among all three. Experiments to characterize the performance of the latest generation TNA in detecting buried landmines and IEDs hidden in culverts were conducted during 2011. This paper describes the second generation system. The experimental setup and methodology are detailed and preliminary comparisons between the performance of first and second generation systems are presented.

Determinants and clinical impact of pressure drift in manoscan anorectal high resolution manometry system.

PubMed

Parthasarathy, G; McMaster, J; Feuerhak, K; Zinsmeister, A R; Bharucha, A E

2016-09-01

Pressure drift (PD), resulting from differences between room and body temperature, reduces the accuracy of pressure measurements with the Manoscan high resolution manometry (HRM) system. Our aims were to assess PD during anorectal HRM. Defined as the residual pressure measured immediately after the catheter was removed, PD was calculated for each sensor and averaged across all 12 sensors in 454 anorectal consecutive studies recorded with 3 HRM catheters. The relationship between PD and study duration, number of prior uses of a catheter, and peak and average pressure exposure during a study were evaluated. The correction of PD with a software algorithm (thermal compensation) was evaluated in 76 studies where the most distal sensor was outside the body. The PD varied among sensors and across catheters. The average PD (7.3 ± 0.2 mmHg) was significantly greater for newer catheters, during longer studies, or when sensors were exposed to higher pressures. Together, these factors explained 81% of the variance in overall PD. After thermal compensation, the uncorrected median PD for the most distal sensor was 2.5-5 mmHg over the study duration. Correcting this changed the interpretation (e.g., as abnormal instead of normal) of at least 1 anorectal parameter in eight of 76 studies. During anorectal HRM, PD declines with catheter use and is greater for newer catheters, when sensors are exposed to higher pressures, and for studies of longer duration. While PD is partially corrected with thermal compensation algorithms, the impact on interpretation is modest. © 2016 John Wiley & Sons Ltd.

Challenges to quantitative applications of Landsat observations for the urban thermal environment.

PubMed

Chen, Feng; Yang, Song; Yin, Kai; Chan, Paul

2017-09-01

Since the launch of its first satellite in 1972, the Landsat program has operated continuously for more than forty years. A large data archive collected by the Landsat program significantly benefits both the academic community and society. Thermal imagery from Landsat sensors, provided with relatively high spatial resolution, is suitable for monitoring urban thermal environment. Growing use of Landsat data in monitoring urban thermal environment is demonstrated by increasing publications on this subject, especially over the last decade. Urban thermal environment is usually delineated by land surface temperature (LST). However, the quantitative and accurate estimation of LST from Landsat data is still a challenge, especially for urban areas. This paper will discuss the main challenges for urban LST retrieval, including urban surface emissivity, atmospheric correction, radiometric calibration, and validation. In addition, we will discuss general challenges confronting the continuity of quantitative applications of Landsat observations. These challenges arise mainly from the scan line corrector failure of the Landsat 7 ETM+ and channel differences among sensors. Based on these investigations, the concerns are to: (1) show general users the limitation and possible uncertainty of the retrieved urban LST from the single thermal channel of Landsat sensors; (2) emphasize efforts which should be done for the quantitative applications of Landsat data; and (3) understand the potential challenges for the continuity of Landsat observation (i.e., thermal infrared) for global change monitoring, while several climate data record programs being in progress. Copyright © 2017. Published by Elsevier B.V.

Thermal remote sensing: theory, sensors, and applications

USDA-ARS?s Scientific Manuscript database

Applications of thermal infrared remote sensing for Earth science research are both varied and wide in scope. They range from understanding thermal energy responses that drive land-atmosphere energy exchanges in the hydrologic cycle, to measurement of dielectric surface properties for snow, ice, an...

Contact stress sensor

DOEpatents

Kotovsky, Jack [Oakland, CA

2012-02-07

A contact stress sensor includes one or more MEMS fabricated sensor elements, where each sensor element of includes a thin non-recessed portion, a recessed portion and a pressure sensitive element adjacent to the recessed portion. An electric circuit is connected to the pressure sensitive element. The circuit includes a thermal compensator and a pressure signal circuit element configured to provide a signal upon movement of the pressure sensitive element.

First applications of the EXTASE thermal probe

NASA Astrophysics Data System (ADS)

Schröer, K.; Seiferlin, K.; Marczewski, W.; Gadomski, S.; Spohn, T.

2003-04-01

EXTASE is a spin-off project from the MUPUS (Rosetta Lander) thermal probe, both funded by DLR. The thermal probe will be tested in various environments and fields, e.g. in snow research, agriculture, permafrost, monitoring waste deposits and the heat released by decomposition, ground truth for remote sensing etc. The probe is a glass-fibre tube of 1cm diameter, about 32 cm long and carries of 16 sensors for measuring temperature profiles. Each of the sensors can also be heated for in situ measurements of the thermal diffusivity of the penetrated layers, from which we can derive the thermal conductivity. All necessary connections and the sensors itself are printed on a foil which is rolled and glued to the inner wall of the tube. This design results in the significant advantage that the measurements can be done in-situ. No excavation of material is required to measure the thermal conductivity, for instance. Presently we are concentrating on soil science and snow research.We made several measurements in different conditions with prototypes of the probe so far. Among other things, we measured soil temperatures together with meteorological boundary conditions in cooperation with the local Institute of Agrophysics in Lublin (Poland). The first measurements in snow under natural conditions were made on Svalbard (Spitzbergen) together with the Alfred-Wegener-Institute in Bremerhaven (Germany). First results of the measuring campaigns are shown.

Optical fiber biocompatible sensors for monitoring selective treatment of tumors via thermal ablation

NASA Astrophysics Data System (ADS)

Tosi, Daniele; Poeggel, Sven; Dinesh, Duraibabu B.; Macchi, Edoardo G.; Gallati, Mario; Braschi, Giovanni; Leen, Gabriel; Lewis, Elfed

2015-09-01

Thermal ablation (TA) is an interventional procedure for selective treatment of tumors, that results in low-invasive outpatient care. The lack of real-time control of TA is one of its main weaknesses. Miniature and biocompatible optical fiber sensors are applied to achieve a dense, multi-parameter monitoring, that can substantially improve the control of TA. Ex vivo measurements are reported performed on porcine liver tissue, to reproduce radiofrequency ablation of hepatocellular carcinoma. Our measurement campaign has a two-fold focus: (1) dual pressure-temperature measurement with a single probe; (2) distributed thermal measurement to estimate point-by-point cells mortality.

Microstructured silicon neutron detectors for security applications

NASA Astrophysics Data System (ADS)

Esteban, S.; Fleta, C.; Guardiola, C.; Jumilla, C.; Pellegrini, G.; Quirion, D.; Rodriguez, J.; Lozano, M.

2014-12-01

In this paper we present the design and performance of a perforated thermal neutron silicon detector with a 6LiF neutron converter. This device was manufactured within the REWARD project workplace whose aim is to develop and enhance technologies for the detection of nuclear and radiological materials. The sensor perforated structure results in a higher efficiency than that obtained with an equivalent planar sensor. The detectors were tested in a thermal neutron beam at the nuclear reactor at the Instituto Superior Técnico in Lisbon and the intrinsic detection efficiency for thermal neutrons and the gamma sensitivity were obtained. The Geant4 Monte Carlo code was used to simulate the experimental conditions, i.e. thermal neutron beam and the whole detector geometry. An intrinsic thermal neutron detection efficiency of 8.6%±0.4% with a discrimination setting of 450 keV was measured.

Using Collar worn Sensors to Forecast Thermal Strain in Military Working Dogs

DTIC Science & Technology

2016-04-22

Using Collar-worn Sensors to Forecast Thermal Strain in Military Working Dogs James R. Williamson, Austin R. Hess, Christopher J. Smalt, Delsey M...Medicine Natick, MA 01760 Abstract—Military working dogs (MWDs) are at high risk of heat strain both during training and missions. Body heat in MWD...correlation of r=0.49 between actual and predicted Tc. I. INTRODUCTION Military Working Dogs (MWDs), working in a team with a handler, are susceptible

In-plane vibration of FG micro/nano-mass sensor based on nonlocal theory under various thermal loading via differential transformation method

NASA Astrophysics Data System (ADS)

Rahmani, O.; Mohammadi Niaei, A.; Hosseini, S. A. H.; Shojaei, M.

2017-01-01

In the present study, free vibration model of a cantilever functionally graded (FG) nanobeam with an attached mass at tip and under various thermal loading and two types of material distribution is introduced. The vibration performance is considered using nonlocal Euler-Bernoulli beam theory. Two types of thermal loading, namely, uniform and nonlinear temperature rises through the thickness direction are considered. Thermo-mechanical properties of FG nano mass sensor are supposed to vary smoothly and continuously throughout the thickness based on power-law and Mori Tanaka distributions of material properties. Eringen non-local elasticity theory is exploited to describe the size dependency of FG nanobeam. The governing equations of the system with both axial and transverse displacements are derived based on Hamilton's principle and solved utilizing the differential transformation method (DTM) to find the non-dimensional natural frequencies. The results have good agreements with those discussing in the literature. After validation of the present model, the effect of various parameters such as mass and position of the attached nano particle, FG power-law exponent, thermal load type, material distribution type and nonlocal parameter on the frequency of nano sensor are studied. It is shown that the present model produces results of high accuracy, and it can be used as a benchmark in future studies of the free vibration of FG Nano-Mass Sensors.

Optical Sensor of Thermal Gas Flow Based on Fiber Bragg Grating.

PubMed

Jiang, Xu; Wang, Keda; Li, Junqing; Zhan, Hui; Song, Zhenan; Che, Guohang; Lyu, Guohui

2017-02-15

This paper aims at solving the problem of explosion proof in measurement of thermal gas flow using electronic sensor by presenting a new type of flow sensor by optical fiber heating. A measuring unit based on fiber Bragg grating (FBG) for fluid temperature and a unit for heat dissipation are designed to replace the traditional electronic sensors. The light in C band from the amplified spontaneous emission (ASE) light source is split, with one part used to heat the absorbing coating and the other part used in the signal processing unit. In the heating unit, an absorbing coating is introduced to replace the traditional resistance heating module to minimize the risk of explosion. The measurement results demonstrate a fine consistency between the flow and temperature difference in simulation. The method to enhance the measurement resolution of flow is also discussed.

An Overview of the Landsat Data Continuity Mission

NASA Technical Reports Server (NTRS)

Irons, James R.; Dwyer, John L.

2010-01-01

The advent of the Landsat Data Continuity Mission (LDCM), currently with a launch readiness date of December, 2012, will see evolutionary changes in the Landsat data products available from the U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center. The USGS initiated a revolution in 2009 when EROS began distributing Landsat data products at no cost to requestors in contrast to the past practice of charging the cost of fulfilling a request; that is, charging $600 per Landsat scene. To implement this drastic change, EROS terminated data processing options for requestors and began to produce all data products using a consistent processing recipe. EROS plans to continue this practice for the LDCM and will required new algorithms to process data from the LDCM sensors. All previous Landsat satellites flew multispectral scanners to collect image data of the global land surface. Additionally, Landsats 4, 5, and 7 flew sensors that acquired imagery for both reflective spectral bands and a single thermal band. In contrast, the LDCM will carry two pushbroom sensors; the Operational Land Imager (OLI) for reflective spectral bands and the Thermal InfraRed Sensor (TIRS) for two thermal bands. EROS is developing the ground data processing system that will both calibrate and correct the data from the thousands of detectors employed by the pushbroom sensors and that will also combine the data from the two sensors to create a single data product with registered data for all of the OLI and TIRS bands.

Infrared non-destructive evaluation method and apparatus

DOEpatents

Baleine, Erwan; Erwan, James F; Lee, Ching-Pang; Stinelli, Stephanie

2014-10-21

A method of nondestructive evaluation and related system. The method includes arranging a test piece (14) having an internal passage (18) and an external surface (15) and a thermal calibrator (12) within a field of view (42) of an infrared sensor (44); generating a flow (16) of fluid characterized by a fluid temperature; exposing the test piece internal passage (18) and the thermal calibrator (12) to fluid from the flow (16); capturing infrared emission information of the test piece external surface (15) and of the thermal calibrator (12) simultaneously using the infrared sensor (44), wherein the test piece infrared emission information includes emission intensity information, and wherein the thermal calibrator infrared emission information includes a reference emission intensity associated with the fluid temperature; and normalizing the test piece emission intensity information against the reference emission intensity.

Radiation tolerant compact image sensor using CdTe photodiode and field emitter array (Conference Presentation)

NASA Astrophysics Data System (ADS)

Masuzawa, Tomoaki; Neo, Yoichiro; Mimura, Hidenori; Okamoto, Tamotsu; Nagao, Masayoshi; Akiyoshi, Masafumi; Sato, Nobuhiro; Takagi, Ikuji; Tsuji, Hiroshi; Gotoh, Yasuhito

2016-10-01

A growing demand on incident detection is recognized since the Great East Japan Earthquake and successive accidents in Fukushima nuclear power plant in 2011. Radiation tolerant image sensors are powerful tools to collect crucial information at initial stages of such incidents. However, semiconductor based image sensors such as CMOS and CCD have limited tolerance to radiation exposure. Image sensors used in nuclear facilities are conventional vacuum tubes using thermal cathodes, which have large size and high power consumption. In this study, we propose a compact image sensor composed of a CdTe-based photodiode and a matrix-driven Spindt-type electron beam source called field emitter array (FEA). A basic principle of FEA-based image sensors is similar to conventional Vidicon type camera tubes, but its electron source is replaced from a thermal cathode to FEA. The use of a field emitter as an electron source should enable significant size reduction while maintaining high radiation tolerance. Current researches on radiation tolerant FEAs and development of CdTe based photoconductive films will be presented.

Design and performance of a rugged standard operative temperature thermometer for avian studies

USGS Publications Warehouse

Bakken, G.S.; Boysen, A.F.; Korschgen, C.E.; Kenow, K.P.; Lima, S.L.

2001-01-01

The lack of a truly satisfactory sensor which can characterize the thermal environment at the spatial scale experienced by small endotherms has hindered study of their thermoregulatory behavior. We describe a general design for a rugged, easily constructed sensor to measure standard operative temperature, Tes. We present specific designs for adult dark-eyed juncos (Junco hyemalis) and hatchling mallards (Anas platyrhynchos). Sensor response was stable and repeatable (??1.4%) over the course of several months. Over the range of conditions for which validation data were available (variable air temperature and wind with negligible net radiation), sensors predicted the mean net heat production of live animals to within ??0.023W (equivalent to ??1??C at Tes= 15??C). The main limit on accuracy was scatter in the data on metabolism and evaporative water loss in live animals. These sensors are far more rugged and easily constructed than the heated taxidermic mounts previously used to measure Tes. These characteristics facilitate the use of significant numbers of sensors in thermal mapping studies of endotherms. ?? 2001 Elsevier Science Ltd. All rights reserved.

Wavelength- or Polarization-Selective Thermal Infrared Detectors for Multi-Color or Polarimetric Imaging Using Plasmonics and Metamaterials

PubMed Central

Ogawa, Shinpei; Kimata, Masafumi

2017-01-01

Wavelength- or polarization-selective thermal infrared (IR) detectors are promising for various novel applications such as fire detection, gas analysis, multi-color imaging, multi-channel detectors, recognition of artificial objects in a natural environment, and facial recognition. However, these functions require additional filters or polarizers, which leads to high cost and technical difficulties related to integration of many different pixels in an array format. Plasmonic metamaterial absorbers (PMAs) can impart wavelength or polarization selectivity to conventional thermal IR detectors simply by controlling the surface geometry of the absorbers to produce surface plasmon resonances at designed wavelengths or polarizations. This enables integration of many different pixels in an array format without any filters or polarizers. We review our recent advances in wavelength- and polarization-selective thermal IR sensors using PMAs for multi-color or polarimetric imaging. The absorption mechanism defined by the surface structures is discussed for three types of PMAs—periodic crystals, metal-insulator-metal and mushroom-type PMAs—to demonstrate appropriate applications. Our wavelength- or polarization-selective uncooled IR sensors using various PMAs and multi-color image sensors are then described. Finally, high-performance mushroom-type PMAs are investigated. These advanced functional thermal IR detectors with wavelength or polarization selectivity will provide great benefits for a wide range of applications. PMID:28772855

Wavelength- or Polarization-Selective Thermal Infrared Detectors for Multi-Color or Polarimetric Imaging Using Plasmonics and Metamaterials.

PubMed

Ogawa, Shinpei; Kimata, Masafumi

2017-05-04

Wavelength- or polarization-selective thermal infrared (IR) detectors are promising for various novel applications such as fire detection, gas analysis, multi-color imaging, multi-channel detectors, recognition of artificial objects in a natural environment, and facial recognition. However, these functions require additional filters or polarizers, which leads to high cost and technical difficulties related to integration of many different pixels in an array format. Plasmonic metamaterial absorbers (PMAs) can impart wavelength or polarization selectivity to conventional thermal IR detectors simply by controlling the surface geometry of the absorbers to produce surface plasmon resonances at designed wavelengths or polarizations. This enables integration of many different pixels in an array format without any filters or polarizers. We review our recent advances in wavelength- and polarization-selective thermal IR sensors using PMAs for multi-color or polarimetric imaging. The absorption mechanism defined by the surface structures is discussed for three types of PMAs-periodic crystals, metal-insulator-metal and mushroom-type PMAs-to demonstrate appropriate applications. Our wavelength- or polarization-selective uncooled IR sensors using various PMAs and multi-color image sensors are then described. Finally, high-performance mushroom-type PMAs are investigated. These advanced functional thermal IR detectors with wavelength or polarization selectivity will provide great benefits for a wide range of applications.

Lightweight ZERODUR: a cost-effective thermally stable approach to both large and small spaceborne telescopes

NASA Astrophysics Data System (ADS)

Hull, Tony; Westerhoff, Thomas

2014-06-01

ZERODUR®, known as the "gold standard" material for systems which require dimensional stability in the presence of gradients and transients, is now available lightweighted to the 85% to 90% level for use in high performance spaceborne telescopes and sensor systems. This establishes a design option that may have cost, testability, performance and risk advantages for an entire sensor system payload. The technical approach to making these primary mirrors is the same, whether the aperture is <0.3m to <4.0m. Since each mirror blank is made from a single monolithic billet of near zero-expansion, isotropic and homogeneous ZERODUR® material, the resulting mirror is very stable over a wide range of scenes and orbits, with minimal to no need for ancillary thermal stability and wavefront sensing and control systems. Telescopes using ZERODUR® and low expansion metering structures can accommodate thermal design challenges of both non-thermal (UV, VIS, LLLTV, NIR, SWIR and mm) and thermal (MWIR, LWIR) imaging systems, and deliver optimal performance. This lightweight mirror technology is discussed, with actual examples by SCHOTT of 0.3m and 1.2m mirrors presented. Lightweight ZERODUR® mirrors offer superior optical performance, attractive cost and aggressive lead times, and are available to present and future spaceborne sensor trades.

MELDI2 Do No Harm Test Series

NASA Technical Reports Server (NTRS)

Swanson, G. T.; Santos, J. A.; White, T. R.; Bruce, W. E.; Kuhl, C. A.; Wright, H. S.

2017-01-01

Mars 2020 will fly the Mars Entry, Descent, and Landing Instrumentation II (MEDLI2) sensor suite consisting of a total of seventeen instrumented thermal sensor plugs, eight pressure transducers, two heat flux sensors, and one radiometer embedded in the thermal protection system (TPS). Of the MEDLI2 instrumentation, eleven instrumented thermal plugs and seven pressure transducers will be installed on the heatshield of the Mars 2020 vehicle while the rest will be installed on the backshell. The goal of the MEDLI2 instrumentation is to directly inform the large performance uncertainties that contribute to the design and validation of a Mars entry system. A better understanding of the entry environment and TPS performance could lead to reduced design margins enabling a greater payload mass-fraction and smaller landing ellipses. To prove that the MEDLI2 system will not degrade the performance of the Mars 2020 TPS, an Aerothermal Do No Harm (DNH) test series was designed and conducted. Like Mars 2020's predecessor, Mars Science Laboratory (MSL), the heatshield material will be Phenolic Impregnated Carbon Ablator (PICA); the Mars 2020 entry conditions are enveloped by the MSL design environments, therefore the development and qualification testing performed during MEDLI is sufficient to show that the similar MEDLI2 heatshield instrumentation will not degrade PICA performance. However, given that MEDLI did not include any backshell instrumentation, the MEDLI2 team was required to design and execute a DNH test series utilizing the backshell TPS material (SLA-561V) with the intended flight sensor suite. To meet the requirements handed down from Mars 2020, the MEDLI2 DNH test series emphasized the interaction between the MEDLI2 sensors and sensing locations with the surrounding backshell TPS and substrucutre. These interactions were characterized by performing environmental testing of four 12" by 12" test panels, which mimicked the construction of the backshell TPS and the integration of the MEDLI2 sensors as seen in Figure 1. The testing included thermal vacuum/ cycling, random vibration, shock, and arc jet testing. The test panels were fabricated by Lockheed Martin, establishing techniques that will be utilized during the Mars 2020 vehicle installation. Each test panel included one thermal sensor plug (two embedded thermocouples), one heat flux sensor, and multiple pressure port holes for evaluation. This presentation will discuss the planning and execution of the MEDLI2 DNH test series. Selected highlights and results of each environmental test will be presented, and lessons learned will be addressed that will feed forward into the planning for the MEDLI2 flight system certification testing.

Comparison of Calibration of Sensors Used for the Quantification of Nuclear Energy Rate Deposition

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

Brun, J.; Reynard-Carette, C.; Tarchalski, M.

This present work deals with a collaborative program called GAMMA-MAJOR 'Development and qualification of a deterministic scheme for the evaluation of GAMMA heating in MTR reactors with exploitation as example MARIA reactor and Jules Horowitz Reactor' between the National Centre for Nuclear Research of Poland, the French Atomic Energy and Alternative Energies Commission and Aix Marseille University. One of main objectives of this program is to optimize the nuclear heating quantification thanks to calculation validated from experimental measurements of radiation energy deposition carried out in irradiation reactors. The quantification of the nuclear heating is a key data especially for themore » thermal, mechanical design and sizing of irradiation experimental devices in specific irradiated conditions and locations. The determination of this data is usually performed by differential calorimeters and gamma thermometers such as used in the experimental multi-sensors device called CARMEN 'Calorimetric en Reacteur et Mesures des Emissions Nucleaires'. In the framework of the GAMMA-MAJOR program a new calorimeter was designed for the nuclear energy deposition quantification. It corresponds to a single-cell calorimeter and it is called KAROLINA. This calorimeter was recently tested during an irradiation campaign inside MARIA reactor in Poland. This new single-cell calorimeter differs from previous CALMOS or CARMEN type differential calorimeters according to three main points: its geometry, its preliminary out-of-pile calibration, and its in-pile measurement method. The differential calorimeter, which is made of two identical cells containing heaters, has a calibration method based on the use of steady thermal states reached by simulating the nuclear energy deposition into the calorimeter sample by Joule effect; whereas the single-cell calorimeter, which has no heater, is calibrated by using the transient thermal response of the sensor (heating and cooling steps). The paper will concern these two kinds of calorimetric sensors. It will focus in particular on studies on their out-of-pile calibrations. Firstly, the characteristics of the sensor designs will be detailed (such as geometry, dimension, material sample, assembly, instrumentation). Then the out-of-pile calibration methods will be described. Furthermore numerical results obtained thanks to 2D axisymmetrical thermal simulations (Finite Element Method, CAST3M) and experimental results will be presented for each sensor. A comparison of the two different thermal sensor behaviours will be realized. To conclude a discussion of the advantages and the drawbacks of each sensor will be performed especially regarding measurement methods. (authors)« less

Experimental Performance of a Micromachined Heat Flux Sensor

NASA Technical Reports Server (NTRS)

Stefanescu, S.; DeAnna, R. G.; Mehregany, M.

1998-01-01

Steady-state and frequency response calibration of a microfabricated heat-flux sensor have been completed. This sensor is batch fabricated using standard, micromachining techniques, allowing both miniaturization and the ability to create arrays of sensors and their corresponding interconnects. Both high-frequency and spatial response is desired, so the sensors are both thin and of small cross-sectional area. Thin-film, temperature-sensitive resistors are used as the active gauge elements. Two sensor configurations are investigated: (1) a Wheatstone-bridge using four resistors; and (2) a simple, two-resistor design. In each design, one resistor (or pair) is covered by a thin layer (5000 A) thermal barrier; the other resistor (or pair) is covered by a thick (5 microns) thermal barrier. The active area of a single resistor is 360 microns by 360 microns; the total gauge area is 1.5 mm square. The resistors are made of 2000 A-thick metal; and the entire gauge is fabricated on a 25 microns-thick flexible, polyimide substrate. Heat flux through the surface changes the temperature of the resistors and produces a corresponding change in resistance. Sensors were calibrated using two radiation heat sources: (1) a furnace for steady-state, and (2) a light and chopper for frequency response.

Freestanding, Fiber-Based, Wearable Temperature Sensor with Tunable Thermal Index for Healthcare Monitoring.

PubMed

Trung, Tran Quang; Le, Hoang Sinh; Dang, Thi My Linh; Ju, Sanghyun; Park, Sang Yoon; Lee, Nae-Eung

2018-06-01

Fiber-based sensors integrated on textiles or clothing systems are required for the next generation of wearable electronic platforms. Fiber-based physical sensors are developed, but the development of fiber-based temperature sensors is still limited. Herein, a new approach to develop wearable temperature sensors that use freestanding single reduction graphene oxide (rGO) fiber is proposed. A freestanding and wearable temperature-responsive rGO fiber with tunable thermal index is obtained using simple wet spinning and a controlled graphene oxide reduction time. The freestanding fiber-based temperature sensor shows high responsivity, fast response time (7 s), and good recovery time (20 s) to temperature. It also maintains its response under an applied mechanical deformation. The fiber device fabricated by means of a simple process is easily integrated into fabric such as socks or undershirts and can be worn by a person to monitor the temperature of the environment and skin temperature without interference during movement and various activities. These results demonstrate that the freestanding fiber-based temperature sensor has great potential for fiber-based wearable electronic platforms. It is also promising for applications in healthcare and biomedical monitoring. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fiber Bragg Gratings for High-Temperature Thermal Characterization

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

Stinson-Bagby, Kelly L.; Fielder, Robert S.

2004-07-01

Fiber Bragg grating (FBG) sensors were used as a characterization tool to study the SAFE-100 thermal simulator at the Nasa Marshal Space Flight Center. The motivation for this work was to support Nasa space nuclear power initiatives through the development of advanced fiber optic sensors for space-based nuclear power applications. Distributed high temperature measurements, up to 1150 deg. C, were made with FBG temperature sensors. Additionally, FBG strain measurements were taken at elevated temperatures to provide a strain profile of the core during operation. This paper will discuss the contribution of these measurements to meet the goals of Nasa Marshallmore » Space Flight Center's Propulsion Research Center. (authors)« less

Thermal and Optical Activation Mechanisms of Nanospring-Based Chemiresistors

PubMed Central

Dobrokhotov, Vladimir; Oakes, Landon; Sowell, Dewayne; Larin, Alexander; Hall, Jessica; Barzilov, Alexander; Kengne, Alex; Bakharev, Pavel; Corti, Giancarlo; Cantrell, Timothy; Prakash, Tej; Williams, Joseph; Bergman, Leah; Huso, Jesse; McIlroy, David

2012-01-01

Chemiresistors (conductometric sensor) were fabricated on the basis of novel nanomaterials—silica nanosprings ALD coated with ZnO. The effects of high temperature and UV illumination on the electronic and gas sensing properties of chemiresistors are reported. For the thermally activated chemiresistors, a discrimination mechanism was developed and an integrated sensor-array for simultaneous real-time resistance scans was built. The integrated sensor response was tested using linear discriminant analysis (LDA). The distinguished electronic signatures of various chemical vapors were obtained at ppm level. It was found that the recovery rate at high temperature drastically increases upon UV illumination. The feasibility study of the activation method by UV illumination at room temperature was conducted. PMID:22778604

Flight model performances of HISUI hyperspectral sensor onboard ISS (International Space Station)

NASA Astrophysics Data System (ADS)

Tanii, Jun; Kashimura, Osamu; Ito, Yoshiyuki; Iwasaki, Akira

2016-10-01

Hyperspectral Imager Suite (HISUI) is a next-generation Japanese sensor that will be mounted on Japanese Experiment Module (JEM) of ISS (International Space Station) in 2019 as timeframe. HISUI hyperspectral sensor obtains spectral images of 185 bands with the ground sampling distance of 20x31 meter from the visible to shortwave-infrared region. The sensor system is the follow-on mission of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) in the visible to shortwave infrared region. The critical design review of the instrument was accomplished in 2014. Integration and tests of an flight model of HISUI hyperspectral sensor is being carried out. Simultaneously, the development of JEM-External Facility (EF) Payload system for the instrument started. The system includes the structure, the thermal control system, the electrical system and the pointing mechanism. The development status and the performances including some of the tests results of Instrument flight model, such as optical performance, optical distortion and radiometric performance are reported.

Flight model of HISUI hyperspectral sensor onboard ISS (International Space Station)

NASA Astrophysics Data System (ADS)

Tanii, Jun; Kashimura, Osamu; Ito, Yoshiyuki; Iwasaki, Akira

2017-09-01

Hyperspectral Imager Suite (HISUI) is a next-generation Japanese sensor that will be mounted on Japanese Experiment Module (JEM) of ISS (International Space Station) in 2019 as timeframe. HISUI hyperspectral sensor obtains spectral images of 185 bands with the ground sampling distance of 20x31 meter from the visible to shortwave-infrared wavelength region. The sensor is the follow-on mission of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) in the visible to shortwave infrared region. The critical design review of the instrument was accomplished in 2014. Integration and tests of a Flight Model (FM) of HISUI hyperspectral sensor have been completed in the beginning of 2017. Simultaneously, the development of JEMExternal Facility (EF) Payload system for the instrument is being carried out. The system includes the structure, the thermal control sub-system and the electrical sub-system. The tests results of flight model, such as optical performance, optical distortion and radiometric performance are reported.

Fiber-Optic Thermal Sensor for TiN Film Crack Monitoring

PubMed Central

Hsu, Hsiang-Chang; Hsieh, Tso-Sheng; Chen, Yi-Chian; Chen, Hung-En; Tsai, Liren

2017-01-01

The study focuses on the thermal and temperature sensitivity behavior of an optical fiber sensor device. In this article, a titanium nitride (TiN)-coated fiber Bragg grating (FBG) sensor fabricated using an ion beam sputtering system was investigated. The reflection spectra of the FBG sensor were tested using R-soft optical software to simulate the refractive index sensitivity. In these experiments, the temperature sensitivity of the TiN FBG was measured at temperatures ranging from 100 to 500 °C using an optical spectrum analyzer (OSA). The results showed that the temperature sensitivity of the proposed TiN FBG sensor reached 12.8 pm/°C for the temperature range of 100 to 300 °C and 20.8 pm/°C for the temperature range of 300 to 500 °C. Additionally, we found that the produced oxidation at temperatures of 400–500 °C caused a crack, with the crack becoming more and more obvious at higher and higher temperatures. PMID:29137131

Fiber Optic Bragg Grating Sensors for Thermographic Detection of Subsurface Anomalies

NASA Technical Reports Server (NTRS)

Allison, Sidney G.; Winfree, William P.; Wu, Meng-Chou

2009-01-01

Conventional thermography with an infrared imager has been shown to be an extremely viable technique for nondestructively detecting subsurface anomalies such as thickness variations due to corrosion. A recently developed technique using fiber optic sensors to measure temperature holds potential for performing similar inspections without requiring an infrared imager. The structure is heated using a heat source such as a quartz lamp with fiber Bragg grating (FBG) sensors at the surface of the structure to detect temperature. Investigated structures include a stainless steel plate with thickness variations simulated by small platelets attached to the back side using thermal grease. A relationship is shown between the FBG sensor thermal response and variations in material thickness. For comparison, finite element modeling was performed and found to agree closely with the fiber optic thermography results. This technique shows potential for applications where FBG sensors are already bonded to structures for Integrated Vehicle Health Monitoring (IVHM) strain measurements and can serve dual-use by also performing thermographic detection of subsurface anomalies.

Infrared-Proximity-Sensor Modules For Robot

NASA Technical Reports Server (NTRS)

Parton, William; Wegerif, Daniel; Rosinski, Douglas

1995-01-01

Collision-avoidance system for articulated robot manipulators uses infrared proximity sensors grouped together in array of sensor modules. Sensor modules, called "sensorCells," distributed processing board-level products for acquiring data from proximity-sensors strategically mounted on robot manipulators. Each sensorCell self-contained and consists of multiple sensing elements, discrete electronics, microcontroller and communications components. Modules connected to central control computer by redundant serial digital communication subsystem including both serial and a multi-drop bus. Detects objects made of various materials at distance of up to 50 cm. For some materials, such as thermal protection system tiles, detection range reduced to approximately 20 cm.

Gold-Based Nanostructures for Ultrafast Dynamic Nanothermometer

NASA Astrophysics Data System (ADS)

Sun, Hongtao

Nano-scale temperature measurements are of significance for fundamental understanding of functional applications and nanosystems, requiring ultimate miniaturization of thermometers with reduced size, maintained sensitivity, simplicity and accuracy of temperature reading. Particularly, grand challenges exist for scenarios of combustion or thermal shock where materials may be subjected to drastic temperature variations and extreme thermal flux, and dynamic thermal sensors with an ultrafast response (seconds to milliseconds) are yet to be developed. Targeting the developments of advanced nano-scale thermal sensors with a fast time response and rapid readout, this thesis reports innovative designs of high surface-to-volume ratio gold nanostructures including ultrathin gold island films on transparent quartz substrates and silica-gold core-shell (SiO2 Au) nanospheres as potential dynamic thermal sensors for accurate temperature determination. The sensing mechanism is based on strong temperature dependences of the thermally-dewetting-induced morphological self-reorganization and characteristic surface plasmon (SP) absorption of the gold nanostructures. The irreversible thermally-induced morphological and optical signatures behave as characteristic "fingerprints" for temperature recording, allowing the retrieval of thermal history ex-situ. The fundamental studies of thermal-induced dewetting process and its corresponding unique optical properties were extensively investigated by high resolution scanning electron microscopy (HR-SEM), atomic force microscopy (AFM), and UV-vis-NIR spectroscopy, which illustrate temperature and time dependent variations. As compared with current nanothermometer technologies such as metal-filled nanotubes, our thermo-sensor offers positively synergistic advantages of ultrafast time response, permanent recording and fast readout of thermal history, and ex-situ capability for effective temperature measurements. In addition, SiO2 Au nanospheres display simultaneously enhanced near bandgap edge (NBE) emissions and suppress defect level emission (DLE) of poly(vinyl alcohol) (PVA) zinc oxide nanoparticles (ZnO NPs), significantly improving the UV emission of the ZnO. Maximum emission enhancement by nearly 4 times was observed using SiO2 Au nanospheres with SP band at 554 nm. The enhanced UV emission is ascribed to the transfer of the energetic electrons excited by SP from gold nanoshells to the conduction band of ZnO. As a result of their superior tunability of surface plasmon resonance (SPR), the SiO2 Au core/shell nanospheres may be very useful in tuning the photoluminescence for a wide range of optoelectronic applications.

Thermal diffusivity measurement of GaAs/AlGaAs thin-film structures

NASA Astrophysics Data System (ADS)

Chen, G.; Tien, C. L.; Wu, X.; Smith, J. S.

1994-05-01

This work develops a new measurement technique that determines the thermal diffusivity of thin films in both parallel and perpendicular directions, and presents experimental results on the thermal diffusivity of GaAs/AlGaAs-based thin-film structures. In the experiment, a modulated laser source heats up the sample and a fast-response temperature sensor patterned directly on the sample picks up the thermal response. From the phase delay between the heating source and the temperature sensor, the thermal diffusivity in either the parallel or perpendicular direction is obtained depending on the experimental configuration. The experiment is performed on a molecular-beam-epitaxy grown vertical-cavity surface-emitting laser (VCSEL) structure. The substrates of the samples are etched away to eliminate the effects of the interface between the film and the substrate. The results show that the thermal diffusivity of the VCSEL structure is 5-7 times smaller than that of its corresponding bulk media. The experiments also provide evidence on the anisotropy of thermal diffusivity caused solely by the effects of interfaces and boundaries of thin films.

Dark and background response stability for the Landsat 8 Thermal Infrared Sensor

USGS Publications Warehouse

Vanderwerff, Kelly; Montanaro, Matthew

2012-01-01

The Thermal Infrared Sensor (TIRS) is a pushbroom sensor that will be a part of the Landsat Data Continuity Mission (LDCM), which is a joint mission between NASA and the USGS. The TIRS instrument will continue to collect the thermal infrared data that are currently being collected by the Thematic Mapper and the Enhanced Thematic Mapper Plus on Landsats 5 and 7, respectively. One of the key requirements of the new sensor is that the dark and background response be stable to ensure proper data continuity from the legacy Landsat instruments. Pre launch testing of the instrument has recently been completed at the NASA Goddard Space Flight Center (GSFC), which included calibration collects that mimic those that will be performed on orbit. These collects include images of a cold plate meant to simulate the deep space calibration source as viewed by the instrument in flight. The data from these collects give insight into the stability of the instrument’s dark and background response, as well as factors that may cause these responses to vary. This paper quantifies the measured background and dark response of TIRS as well as its stability.

Shape memory polymer sensors for tracking cumulative environmental exposure

NASA Astrophysics Data System (ADS)

Snyder, Ryan; Rauscher, Michael; Vining, Ben; Havens, Ernie; Havens, Teresa; McFerran, Jace

2010-04-01

Cornerstone Research Group Inc. (CRG) has developed environmental exposure tracking (EET) sensors using shape memory polymers (SMP) to monitor the degradation of perishable items, such as munitions, foods and beverages, or medicines, by measuring the cumulative exposure to temperature and moisture. SMPs are polymers whose qualities have been altered to give them dynamic shape "memory" properties. Under thermal or moisture stimuli, the SMP exhibits a radical change from a rigid thermoset to a highly flexible, elastomeric state. The dynamic response of the SMP can be tailored to match the degradation profile of the perishable item. SMP-based EET sensors require no digital memory or internal power supply and provide the capability of inexpensive, long-term life cycle monitoring of thermal and moisture exposure over time. This technology was developed through Phase I and Phase II SBIR efforts with the Navy. The emphasis of current research centers on transitioning SMP materials from the lab bench to a production environment. Here, CRG presents the commercialization progress of thermally-activated EET sensors, focusing on fabrication scale-up, process refinements, and quality control. In addition, progress on the development of vapor pressure-responsive SMP (VPR-SMP) will be discussed.

The Sensor Irony: How Reliance on Sensor Technology is Limiting Our View of the Battlefield

DTIC Science & Technology

2010-05-10

thermal ) camera, as well as a laser illuminator/range finder.73 Similar to the MQ- 1 , the MQ-9 Reaper is primarily a strike asset for emerging targets...Wescam 14TS. 1 Both systems have an Electro-optical (daylight) TV camera, an Infra-red ( thermal ) camera, as well as a laser illuminator/range finder...Report Documentation Page Form Approved OMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour

Electronic Skin with Multifunction Sensors Based on Thermosensation.

PubMed

Zhao, Shuai; Zhu, Rong

2017-04-01

A multifunctional electronic skin (e-skin) with multimodal sensing capabilities of perceiving mechanical and thermal stimuli, discriminating matter type, and sensing wind is developed using the thermosensation of a platinum ribbon array, whose temperature varies with conductive or convective heat transfer toward the surroundings. Pressure is perceived by a porous elastomer covering on the heated platinum ribbon, which bears mechanical-thermal conversion to allow high integration with other sensors. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Thermal Infrared Sensor on the Landsat Data Continuity Mission

NASA Technical Reports Server (NTRS)

Reuter, Dennis; Richardson, Cathy; Irons, James; Allen, Rick; Anderson, Martha; Budinoff, Jason; Casto, Gordon; Coltharp, Craig; Finneran, Paul; Forsbacka, Betsy;

Error compensation for thermally induced errors on a machine tool

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

Krulewich, D.A.

1996-11-08

Heat flow from internal and external sources and the environment create machine deformations, resulting in positioning errors between the tool and workpiece. There is no industrially accepted method for thermal error compensation. A simple model has been selected that linearly relates discrete temperature measurements to the deflection. The biggest problem is how to locate the temperature sensors and to determine the number of required temperature sensors. This research develops a method to determine the number and location of temperature measurements.

Non-Contact Stiffness Measurement of a Suspended Single Walled Carbon Nanotube Device

NASA Technical Reports Server (NTRS)

Zheng, Yun; Su, Chanmin; Getty, Stephanie

2010-01-01

A new nanoscale electric field sensor was developed for studying triboelectric charging in terrestrial and Martian dust devils. This sensor is capable to measure the large electric fields for large dust devils without saturation. However, to quantify the electric charges and the field strength it is critical to calibrate the mechanical stiffness of the sensor devices. We performed a technical feasibility study of the Nano E-field Sensor stiffness by a non-contact stiffness measurement method. The measurement is based on laser Doppler vibrometer measurement of the thermal noise due to energy flunctuations in the devices. The experiment method provides a novel approach to acquire data that is essential in analyzing the quantitative performance of the E-field Nano Sensor. To carry out the non-contact stiffness measurement, we fabricated a new Single-Walled Carbon Nanotube (SWCNT) E-field sensor with different SWCNTs suspension conditions. The power spectra of the thermal induced displacement in the nano E-field sensor were measured at the accuracy of picometer. The power spectra were then used to derive the mechanical stiffness of the sensors. Effect of suspension conditions on stiffness and sensor sensitivty was discussed. After combined deformation and resistivity measurement, we can compare with our laboratory testing and field testing results. This new non-contact measurement technology can also help to explore to other nano and MEMS devices in the future.

A simple method to predict body temperature of small reptiles from environmental temperature.

PubMed

Vickers, Mathew; Schwarzkopf, Lin

2016-05-01

To study behavioral thermoregulation, it is useful to use thermal sensors and physical models to collect environmental temperatures that are used to predict organism body temperature. Many techniques involve expensive or numerous types of sensors (cast copper models, or temperature, humidity, radiation, and wind speed sensors) to collect the microhabitat data necessary to predict body temperatures. Expense and diversity of requisite sensors can limit sampling resolution and accessibility of these methods. We compare body temperature predictions of small lizards from iButtons, DS18B20 sensors, and simple copper models, in both laboratory and natural conditions. Our aim was to develop an inexpensive yet accurate method for body temperature prediction. Either method was applicable given appropriate parameterization of the heat transfer equation used. The simplest and cheapest method was DS18B20 sensors attached to a small recording computer. There was little if any deficit in precision or accuracy compared to other published methods. We show how the heat transfer equation can be parameterized, and it can also be used to predict body temperature from historically collected data, allowing strong comparisons between current and previous environmental temperatures using the most modern techniques. Our simple method uses very cheap sensors and loggers to extensively sample habitat temperature, improving our understanding of microhabitat structure and thermal variability with respect to small ectotherms. While our method was quite precise, we feel any potential loss in accuracy is offset by the increase in sample resolution, important as it is increasingly apparent that, particularly for small ectotherms, habitat thermal heterogeneity is the strongest influence on transient body temperature.

Thermal Evaluation of Fiber Bragg Gratings at Extreme Temperatures

NASA Technical Reports Server (NTRS)

Juergens, Jeffrey; Adamovsky, Grigory; Bhatt, Ramakrishna; Morscher, Gregory; Floyd, Bertram

2005-01-01

The development of integrated fiber optic sensors for use in aerospace health monitoring systems demands that the sensors be able to perform in extreme environments. In order to use fiber optic sensors effectively in an extreme environment one must have a thorough understanding of the sensor's capabilities, limitations, and performance under extreme environmental conditions. This paper reports on our current sensor evaluation examining the performance of freestanding fiber Bragg gratings (FBG) at extreme temperatures. While the ability of FBGs to survive at extreme temperatures has been established, their performance and long term survivability is not well documented. At extreme temperatures the grating structure would be expected to dissipate, degrading the sensors performance and eventually ceasing to return a detectable signal. The fiber jacket will dissipate leaving a brittle, unprotected fiber. For FBGs to be used in aerospace systems their performance and limitations need to be thoroughly understood at extreme temperatures. As the limits of the FBGs performance are pushed the long term survivability and performance of the sensor comes into question. We will not only examine the ability of FBGs to survive extreme temperatures but also look at their performance during many thermal cycles. This paper reports on test results of the performance of thermal cycling commercially available FBGs, at temperatures up to 1000 C, seen in aerospace applications. Additionally this paper will report on the performance of commercially available FBGs held at 1000 C for hundreds of hours. Throughout the evaluation process, various parameters of the FBGs performance were monitored and recorded. Several test samples were subjected to identical test conditions to allow for statistical analysis of the data. Test procedures, calibrations, referencing techniques, performance data, and interpretations and explanations of results are presented in the paper along with directions for future research.

Nanocrystalline mesoporous SMO thin films prepared by sol gel process for MEMS-based hydrogen sensor

NASA Astrophysics Data System (ADS)

Gong, Jianwei; Fei, Weifeng; Seal, Sudipta; Chen, Quanfang

2004-01-01

MEMS based SnO2 gas sensor with sol gel synthesized mesoporous nanocrystalline (<10 nm) semiconductor thin (100~150 nm) film has been recently developed. The SnO2 nano film is fabricated with the combination of polymeric sol gel chemistry with block copolymers used for structure directing agents. The novel hydrogen sensor has a fast response time (1s) and quick recovery time (3s), as well as good sensitivity (about 90%), comparing to other hydrogen sensors developed. The improved capabilities are credited to the large surface to volume ratio of gas sensing thin film with nano sized porous surface topology, which can greatly increase the sensitivity even at relatively low working temperature. The gas sensing film is deposited onto a thin dielectric membrane of low thermal conductivity, which provides good thermal isolation between substrate and the gas-sensitive heated area on the membrane. In this way the power consumption can be kept very low. Since the fabrication process is completely compatible with IC industry, it makes mass production possible and greatly reduces the cost. The working temperature of the new sensor can be reduced as low as 100°C. The low working temperature posse advantages such as lower power consumption, lower thermal induced signal shift as well as safe detection in certain environments where temperature is strictly limited.

Low-temperature cross-talk magnetic-field sensor based on tapered all-solid waveguide-array fiber and magnetic fluids.

PubMed

Miao, Yinping; Ma, Xixi; Wu, Jixuan; Song, Binbin; Zhang, Hao; Zhang, Kailiang; Liu, Bo; Yao, Jianquan

2015-08-15

A compact fiber-optic magnetic-field sensor based on tapered all-solid waveguide-array fiber (WAF) and magnetic fluid (MF) has been proposed and experimentally demonstrated. The tapered all-solid WAF is fabricated by using a fusion splicer, and the sensor is formed by immersing the tapered all-solid WAF into the MF. The transmission spectra have been measured and analyzed under different magnetic-field intensities. Experimental results show that the acquired magnetic-field sensitivity is 44.57 pm/Oe for a linear magnetic-field intensity range from 50 to 200 Oe. All-solid WAF has very similar thermal expansion coefficient for high- and low-refractive-index glasses, so mode profile is not affected by thermal drifts. Also, magnetically induced refractive-index changes into the ferrofluid are of the order of ∼5×10(-2), while the corresponding thermally induced refractive-index changes into the ferrofluid are expected to be lower. The temperature response has also been detected, and the temperature-induced wavelength shift perturbation is less than 0.3 nm from temperature of 26.9°C-44°C. The proposed magnetic-field sensor has such advantages as low temperature sensitivity, simple structure, and ease of fabrication. It also indicates that the magnetic-field sensor based on tapered all-solid WAF and MF is helpful to reduce temperature cross-sensitivity for the measurement of magnetic field.

Electromagnetic Environmental Effects System Testing

DTIC Science & Technology

2013-11-20

battery packs or air turbine power generators. The sensitivity of the entire instrumentation system should be taken into consideration from the sensor ...Electromagnetic Radiation to Ordnance (HERO) sensors , pneumatic switching, and those equipments associated with fiber optic technology. c. Test...Field probes to determine environment -Thermal heating sensors (e.g., FISO or Metricor systems) used to detect bridgewire heating induced by

Micromachined lab-on-a-tube sensors for simultaneous brain temperature and cerebral blood flow measurements.

PubMed

Li, Chunyan; Wu, Pei-Ming; Hartings, Jed A; Wu, Zhizhen; Cheyuo, Cletus; Wang, Ping; LeDoux, David; Shutter, Lori A; Ramaswamy, Bharat Ram; Ahn, Chong H; Narayan, Raj K

2012-08-01

This work describes the development of a micromachined lab-on-a-tube device for simultaneous measurement of brain temperature and regional cerebral blood flow. The device consists of two micromachined gold resistance temperature detectors with a 4-wire configuration. One is used as a temperature sensor and the other as a flow sensor. The temperature sensor operates with AC excitation current of 500 μA and updates its outputs at a rate of 5 Hz. The flow sensor employs a periodic heating and cooling technique under constant-temperature mode and updates its outputs at a rate of 0.1 Hz. The temperature sensor is also used to compensate for temperature changes during the heating period of the flow sensor to improve the accuracy of flow measurements. To prevent thermal and electronic crosstalk between the sensors, the temperature sensor is located outside the "thermal influence" region of the flow sensor and the sensors are separated into two different layers with a thin-film Copper shield. We evaluated the sensors for accuracy, crosstalk and long-term drift in human blood-stained cerebrospinal fluid. These in vitro experiments showed that simultaneous temperature and flow measurements with a single lab-on-a-tube device are accurate and reliable over the course of 5 days. It has a resolution of 0.013 °C and 0.18 ml/100 g/min; and achieves an accuracy of 0.1 °C and 5 ml/100 g/min for temperature and flow sensors respectively. The prototype device and techniques developed here establish a foundation for a multi-sensor lab-on-a-tube, enabling versatile multimodality monitoring applications.

Evaluation of high temperature superconductive thermal bridges for space-borne cryogenic infrared detectors

NASA Technical Reports Server (NTRS)

Scott, Elaine P.

1993-01-01

The focus of this research is on the reduction of the refrigeration requirements for infrared sensors operating in space through the use of high temperature superconductive (HTS) materials as electronic leads between the cooled sensors and the relatively warmer data acquisition components. Specifically, this initial study was directed towards the design of an experiment to quantify the thermal performance of these materials in the space environment. First, an intensive review of relevant literature was undertaken, and then, design requirements were formulated. From this background information, a preliminary experimental design was developed. Additional studies will involve a thermal analysis of the experiment and further modifications of the experimental design.

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.

The EXTASE thermal probe: Laboratory investigation and modelling of thermal properties

NASA Astrophysics Data System (ADS)

Kaufmann, E.; Knollenberg, J.; Kargl, G.; Koemle, N. I.

2011-10-01

In recent years space missions including landing devices are getting more important. These missions allow in-situ measurements and lead therefore to information on the structure and behavior of extraterrestrial surface and subsurface layers. Sensors used for this kind of missions have to be adapted to the non-terrestrial environment conditions. The better the properties of the single elements of each sensor are known, the more precise are the results from the data evaluation of in-situ measurements. We present the results of thermal conductivity measurements and simulations done for the fiber compound tube used as structural element for the heating segments of the MUPUS-PEN and EXTASE - a spin-off project of Rosetta/MUPUS.

Gyrocopter-Based Remote Sensing Platform

NASA Astrophysics Data System (ADS)

Weber, I.; Jenal, A.; Kneer, C.; Bongartz, J.

2015-04-01

In this paper the development of a lightweight and highly modularized airborne sensor platform for remote sensing applications utilizing a gyrocopter as a carrier platform is described. The current sensor configuration consists of a high resolution DSLR camera for VIS-RGB recordings. As a second sensor modality, a snapshot hyperspectral camera was integrated in the aircraft. Moreover a custom-developed thermal imaging system composed of a VIS-PAN camera and a LWIR-camera is used for aerial recordings in the thermal infrared range. Furthermore another custom-developed highly flexible imaging system for high resolution multispectral image acquisition with up to six spectral bands in the VIS-NIR range is presented. The performance of the overall system was tested during several flights with all sensor modalities and the precalculated demands with respect to spatial resolution and reliability were validated. The collected data sets were georeferenced, georectified, orthorectified and then stitched to mosaics.

Self-Powered Wireless Sensors

NASA Technical Reports Server (NTRS)

Dynys, Fred; Sayir, Ali

2008-01-01

NASA's integrated vehicle health management (IVHM) program offers the potential to improve aeronautical safety, reduce cost and improve performance by utilizing networks of wireless sensors. Development of sensor systems for engine hot sections will provide real-time data for prognostics and health management of turbo-engines. Sustainable power to embedded wireless sensors is a key challenge for prolong operation. Harvesting energy from the environment has emerged as a viable technique for power generation. Thermoelectric generators provide a direct conversion of heat energy to electrical energy. Micro-power sources derived from thermoelectric films are desired for applications in harsh thermal environments. Silicon based alloys are being explored for applications in high temperature environments containing oxygen. Chromium based p-type Si/Ge alloys exhibit Seebeck coefficients on the order of 160 micro V/K and low thermal conductance of 2.5 to 5 W/mK. Thermoelectric properties of bulk and thin film silicides will be discussed

Implications of Weak Link Effects on Thermal Characteristics of Transition-Edge Sensors

NASA Technical Reports Server (NTRS)

Bailey, Catherine

2011-01-01

Weak link behavior in transition-edge sensor (TES) devices creates the need for a more careful characterization of a device's thermal characteristics through its transition. This is particularly true for small TESs where a small change in the measurement current results in large changes in temperature. A highly current-dependent transition shape makes accurate thermal characterization of the TES parameters through the transition challenging. To accurately interpret measurements, especially complex impedance, it is crucial to know the temperature-dependent thermal conductance, G(T), and heat capacity, C(T), at each point through the transition. We will present data illustrating these effects and discuss how we overcome the challenges that are present in accurately determining G and T from IV curves. We will also show how these weak link effects vary with TES size.

Fabrication and Testing of a Thin-Film Heat Flux Sensor for a Stirling Convertor

NASA Technical Reports Server (NTRS)

Wilson, Scott D.; Fralick, Gustave; Wrbanek, John; Sayir, Ali

2009-01-01

The NASA Glenn Research Center (GRC) has been testing high efficiency free-piston Stirling convertors for potential use in radioisotope power systems since 1999. Stirling convertors are being operated for many years to demonstrate a radioisotope power system capable of providing reliable power for potential multi-year missions. Techniques used to monitor the convertors for change in performance include measurements of temperature, pressure, energy addition, and energy rejection. Micro-porous bulk insulation is used in the Stirling convertor test set up to minimize the loss of thermal energy from the electric heat source to the environment. The insulation is characterized before extended operation, enabling correlation of the net thermal energy addition to the convertor. Aging microporous bulk insulation changes insulation efficiency, introducing errors in the correlation for net thermal energy addition. A thin-mm heat flux sensor was designed and fabricated to directly measure the net thermal energy addition to the Stirling convertor. The fabrication techniques include slip casting and using Physical Vapor Deposition (PVD). One micron thick noble metal thermocouples measure temperature on the surface of an Alumina ceramic disc and heat flux is calculated. Fabrication, integration, and test results of a thin film heat flux sensor are presented.

Fabrication and Testing of a Thin-Film Heat Flux Sensor for a Stirling Convertor

NASA Technical Reports Server (NTRS)

Wilson, Scott D.; Fralick, Gus c.; Wrbanek, John D.; Sayir, Ali

2010-01-01

The NASA Glenn Research Center (GRC) has been testing high-efficiency free-piston Stirling convertors for potential use in radioisotope power systems since 1999. Stirling convertors are being operated for many years to demonstrate a radioisotope power system capable of providing reliable power for potential multiyear missions. Techniques used to monitor the convertors for change in performance include measurements of temperature, pressure, energy addition, and energy rejection. Micro-porous bulk insulation is used in the Stirling convertor test setup to minimize the loss of thermal energy from the electric heat source to the environment. The insulation is characterized before extended operation, enabling correlation of the net thermal energy addition to the convertor. Aging micro-porous bulk insulation changes insulation efficiency, introducing errors in the correlation for net thermal energy addition. A thin-film heat flux sensor was designed and fabricated to directly measure the net thermal energy addition to the Stirling convertor. The fabrication techniques include slipcasting and using Physical Vapor Deposition (PVD). One-micron-thick noble metal thermocouples measure temperature on the surface of an alumina ceramic disk and heat flux is calculated. Fabrication, integration, and test results of a thin-film heat flux sensor are presented.

Qualification of Bonding Process of Temperature Sensors to Extreme Temperature Deep Space Missions

NASA Technical Reports Server (NTRS)

Ramesham, Rajeshuni; Kitiyakara, Amarit; Redick, Richard; Sunada, Eric T.

2011-01-01

A process has been explored based on the state-of-the-art technology to bond the platinum resistance thermometer (PRT) on to potential aerospace material such as a flat aluminum surface and a flexible copper tube to simulate coaxial cable for the flight applications. Primarily, PRTs were inserted into a metal plated copper braid to avoid stresses on the sensor while attaching the sensor with braid to the base material for long duration deep space missions. Appropriate pretreatment has been implemented in this study to enhance the adhesion of the PRTs to the base material. NuSil product has been chosen in this research to attach PRT to the base materials. The resistance (approx.1.1 k(Omega)) of PRTs has been electrically monitored continuously during the qualification thermal cycling testing from -150 C to +120 C and -100 C to -35 C. The test hardware has been thermal cycled three times the mission life per JPL design principles for JUNO project. No PRT failures were observed during and after the PRT thermal cycling qualification test for extreme temperature environments. However, there were some failures associated with staking of the PRT pig tails as a result of thermal cycling qualification test.

Isolation of Thermal and Strain Responses in Composites Using Embedded Fiber Bragg Grating Temperature Sensors

DTIC Science & Technology

2013-05-10

13. SUPPLEMENTARY NOTES 14. ABSTRACT In this research, fiber Bragg grating ( FBG ) optical temperature sensors are used for structural health...surface of a composite structure. FBG sensors also respond to axial strain in the optical fiber, thus any structural strain experienced by the composite...features. First, a three-dimensional array of FBG temperature sensors has been embedded in a carbon/epoxy composite structure, consisting of both in

Thermal Hysteresis of MEMS Packaged Capacitive Pressure Sensor (CPS) Based 3C-SiC

NASA Astrophysics Data System (ADS)

Marsi, N.; Majlis, B. Y.; Mohd-Yasin, F.; Hamzah, A. A.; Mohd Rus, A. Z.

2016-11-01

Presented herein are the effects of thermal hysteresis analyses of the MEMS packaged capacitive pressure sensor (CPS). The MEMS CPS was employed on Si-on-3C-SiC wafer that was performed using the hot wall low-pressure chemical vapour deposition (LPCVD) reactors at the Queensland Micro and Nanotechnology Center (QMNC), Griffith University and fabricated using the bulk-micromachining process. The MEMS CPS was operated at an extreme temperature up to 500°C and high external pressure at 5.0 MPa. The thermal hysteresis phenomenon that causes the deflection, strain and stress on the 3C-SiC diaphragm spontaneously influence the MEMS CPS performances. The differences of temperature, hysteresis, and repeatability test were presented to demonstrate the functionality of the MEMS packaged CPS. As expected, the output hysteresis has a low hysteresis (less than 0.05%) which has the hardness greater than the traditional silicon. By utilizing this low hysteresis, it was revealed that the MEMS packaged CPS has high repeatability and stability of the sensor.

Effects of electrostatic discharge on three cryogenic temperature sensor models

NASA Astrophysics Data System (ADS)

Courts, S. Scott; Mott, Thomas B.

2014-01-01

Cryogenic temperature sensors are not usually thought of as electrostatic discharge (ESD) sensitive devices. However, the most common cryogenic thermometers in use today are thermally sensitive diodes or resistors - both electronic devices in their base form. As such, they are sensitive to ESD at some level above which either catastrophic or latent damage can occur. Instituting an ESD program for safe handling and installation of the sensor is costly and it is desirable to balance the risk of ESD damage against this cost. However, this risk cannot be evaluated without specific knowledge of the ESD vulnerability of the devices in question. This work examines three types of cryogenic temperature sensors for ESD sensitivity - silicon diodes, Cernox{trade mark, serif} resistors, and wire wound platinum resistors, all manufactured by Lake Shore Cryotronics, Inc. Testing was performed per TIA/EIA FOTP129 (Human Body Model). Damage was found to occur in the silicon diode sensors at discharge levels of 1,500 V. For Cernox{trade mark, serif} temperature sensors, damage was observed at 3,500 V. The platinum temperature sensors were not damaged by ESD exposure levels of 9,900 V. At the lower damage limit, both the silicon diode and the Cernox{trade mark, serif} temperature sensors showed relatively small calibration shifts of 1 to 3 K at room temperature. The diode sensors were stable with time and thermal cycling, but the long term stability of the Cernox{trade mark, serif} sensors was degraded. Catastrophic failure occurred at higher levels of ESD exposure.

Particle Characterization for a Protein Drug Product Stored in Pre-Filled Syringes Using Micro-Flow Imaging, Archimedes, and Quartz Crystal Microbalance with Dissipation.

PubMed

Zheng, Songyan; Puri, Aastha; Li, Jinjiang; Jaiswal, Archana; Adams, Monica

2017-01-01

Micro-flow imaging (MFI) has been used for formulation development for analyzing sub-visible particles. Archimedes, a novel technique for analyzing sub-micron particles, has been considered as an orthogonal method to currently existing techniques. This study utilized these two techniques to investigate the effectiveness of polysorbate (PS-80) in mitigating the particle formation of a therapeutic protein formulation stored in silicone oil-coated pre-filled syringes. The results indicated that PS-80 prevented the formation of both protein and silicone oil particles. In the case of protein particles, PS-80 might involve in the interactions with the hydrophobic patches of protein, air bubbles, and the stressed surfaces of silicone oil-coated pre-filled syringes. Such interactions played a role in mitigating the formation of protein particles. Subsequently, quartz crystal microbalance with dissipation (QCM-D) was utilized to characterize the interactions associated with silicone oil, protein, and PS-80 in the solutions. Based on QCM-D results, we proposed that PS-80 likely formed a layer on the interior surfaces of syringes. As a result, the adsorbed PS-80 might block the leakage of silicone oil from the surfaces to solution so that the silicone oil particles were mitigated at the presence of PS-80. Overall, this study demonstrated the necessary of utilizing these three techniques cooperatively in order to better understand the interfacial role of PS-80 in mitigating the formation of protein and silicone oil particles.

The measurements of water flow rates in the straight microchannel based on the scanning micro-PIV technique

NASA Astrophysics Data System (ADS)

Wang, H. L.; Han, W.; Xu, M.

2011-12-01

Measurement of the water flow rate in microchannel has been one of the hottest points in the applications of microfluidics, medical, biological, chemical analyses and so on. In this study, the scanning microscale particle image velocimetry (scanning micro-PIV) technique is used for the measurements of water flow rates in a straight microchannel of 200μm width and 60μm depth under the standard flow rates ranging from 2.481μL/min to 8.269μL/min. The main effort of this measurement technique is to obtain three-dimensional velocity distribution on the cross sections of microchannel by measuring velocities of the different fluid layers along the out-of-plane direction in the microchannel, so the water flow rates can be evaluated from the discrete surface integral of velocities on the cross section. At the same time, the three-dimensional velocity fields in the measured microchannel are simulated numerically using the FLUENT software in order to verify the velocity accuracy of measurement results. The results show that the experimental values of flow rates are well consistent to the standard flow rates input by the syringe pump and the compared results between numerical simulation and experiment are consistent fundamentally. This study indicates that the micro-flow rate evaluated from three-dimensional velocity by the scanning micro-PIV technique is a promising method for the micro-flow rate research.

Stimulation and inhibition of bacterial growth by caffeine dependent on chloramphenicol and a phenolic uncoupler--a ternary toxicity study using microfluid segment technique.

PubMed

Cao, Jialan; Kürsten, Dana; Schneider, Steffen; Köhler, J Michael

2012-10-01

A droplet-based microfluidic technique for the fast generation of three dimensional concentration spaces within nanoliter segments was introduced. The technique was applied for the evaluation of the effect of two selected antibiotic substances on the toxicity and activation of bacterial growth by caffeine. Therefore a three-dimensional concentration space was completely addressed by generating large sequences with about 1150 well separated microdroplets containing 216 different combinations of concentrations. To evaluate the toxicity of the ternary mixtures a time-resolved miniaturized optical double endpoint detection unit using a microflow-through fluorimeter and a two channel microflow-through photometer was used for the simultaneous analysis of changes on the endogenous cellular fluorescence signal and on the cell density of E. coli cultivated inside 500 nL microfluid segments. Both endpoints supplied similar results for the dose related cellular response. Strong non-linear combination effects, concentration dependent stimulation and the formation of activity summits on bolographic maps were determined. The results reflect a complex response of growing bacterial cultures in dependence on the combined effectors. A strong caffeine induced enhancement of bacterial growth was found at sublethal chloramphenicol and sublethal 2,4-dinitrophenol concentrations. The reliability of the method was proved by a high redundancy of fluidic experiments. The results indicate the importance of multi-parameter investigations for toxicological studies and prove the potential of the microsegmented flow technique for such requirements.

A low cost thermal infrared hyperspectral imager for small satellites

NASA Astrophysics Data System (ADS)

Crites, S. T.; Lucey, P. G.; Wright, R.; Garbeil, H.; Horton, K. A.

2011-06-01

The traditional model for space-based earth observations involves long mission times, high cost, and long development time. Because of the significant time and monetary investment required, riskier instrument development missions or those with very specific scientific goals are unlikely to successfully obtain funding. However, a niche for earth observations exploiting new technologies in focused, short lifetime missions is opening with the growth of the small satellite market and launch opportunities for these satellites. These low-cost, short-lived missions provide an experimental platform for testing new sensor technologies that may transition to larger, more long-lived platforms. The low costs and short lifetimes also increase acceptable risk to sensors, enabling large decreases in cost using commercial off the shelf (COTS) parts and allowing early-career scientists and engineers to gain experience with these projects. We are building a low-cost long-wave infrared spectral sensor, funded by the NASA Experimental Project to Stimulate Competitive Research program (EPSCOR), to demonstrate the ways in which a university's scientific and instrument development programs can fit into this niche. The sensor is a low-mass, power efficient thermal hyperspectral imager with electronics contained in a pressure vessel to enable the use of COTS electronics, and will be compatible with small satellite platforms. The sensor, called Thermal Hyperspectral Imager (THI), is based on a Sagnac interferometer and uses an uncooled 320x256 microbolometer array. The sensor will collect calibrated radiance data at long-wave infrared (LWIR, 8-14 microns) wavelengths in 230-meter pixels with 20 wavenumber spectral resolution from a 400-km orbit.

On the importance of telemetric temperature sensor location during intraperitoneal implantation in rats.

PubMed

Chapon, P A; Bulla, J; Gauthier, A; Moussay, S

2014-04-01

This study aims to assess the thermal homogeneity of the intraperitoneal (IP) cavity and the relevance of using a fixed telemetric temperature sensor at a given location in studying rodents. Ten rats were intraperitoneally implanted with three Jonah® capsules each; after assessing the accuracy and reliability of the sensors. Two capsules were attached, one to the right iliac fossa (RIF) and the other to the left hypochondrium (LH), and another was placed between the intestines but not attached (Free). In the ex vivo condition, the differences between sensors and reference values remained in the range of ±0.1. In the in vivo condition, each sensor enabled the observation of temperature patterns. However, sensor location affected mean and median temperature values while the rats were moving freely. Indeed, temperature data collected in the LH were 0.1 significantly higher than those collected in the RIF and temperature data collected in the LH were 0.11 significantly higher than those collected with the Free capsules. In in vivo conditions, intra-sensor variability of temperature data was not affected by sensor location. Taking into account sensor accuracy, similar intra-sensor variability, and mean differences observed between the three locations, the impact of sensor location within the IP cavity could be considered negligible. In in vivo conditions, temperature differences between locations regularly exceeded ±0.2 and reached up to 2.5. These extreme values could be explained by behavioral factors such as food or water intake. Finally, considering the good thermal homogeneity of the IP cavity and possible adverse consequences of sensor attachment, it seems better to let sensors range free within the cavity.

Measuring Thicknesses of Coatings on Metals

NASA Technical Reports Server (NTRS)

Cotty, Glenn M., Jr.

1986-01-01

Digital light sensor and eddy-current sensor measure thickness without contact. Surface of Coating reflects laser beam to optical sensor. Position of reflected spot on sensor used by microcomputer to calculate coating thickness. Eddy-current sensor maintains constant distance between optical sensor and metal substrate. When capabilities of available components fully exploited, instrument measures coatings from 0.001 to 6 in. (0.0025 to 15 cm) thick with accuracy of 1 part in 4,000. Instrument readily incorporated in automatic production and inspection systems. Used to inspect thermal-insulation layers, paint, and protective coatings. Also used to control application of coatings to preset thicknesses.

Life cycle monitoring of lithium-ion polymer batteries using cost-effective thermal infrared sensors with applications for lifetime prediction

NASA Astrophysics Data System (ADS)

Zhou, Xunfei; Malik, Anav; Hsieh, Sheng-Jen

2017-05-01

Lithium-ion batteries have become indispensable parts of our lives for their high-energy density and long lifespan. However, failure due to from abusive usage conditions, flawed manufacturing processes, and aging and adversely affect battery performance and even endanger people and property. Therefore, battery cells that are failing or reaching their end-of-life need to be replaced. Traditionally, battery lifetime prediction is achieved by analyzing data from current, voltage and impedance sensors. However, such a prognostic system is expensive to implement and requires direct contact. In this study, low-cost thermal infrared sensors were used to acquire thermographic images throughout the entire lifetime of small scale lithium-ion polymer batteries (410 cycles). The infrared system (non-destructive) took temperature readings from multiple batteries during charging and discharging cycles of 1C. Thermal characteristics of the batteries were derived from the thermographic images. A time-dependent and spatially resolved temperature mapping was obtained and quantitatively analyzed. The developed model can predict cycle number using the first 10 minutes of surface temperature data acquired through infrared imaging at the beginning of the cycle, with an average error rate of less than 10%. This approach can be used to correlate thermal characteristics of the batteries with life cycles, and to propose cost-effective thermal infrared imaging applications in battery prognostic systems.

Performance of an Advanced Stirling Convertor Based on Heat Flux Sensor Measurements

NASA Technical Reports Server (NTRS)

Wilson, Dcott D.

2012-01-01

The U.S. Department of Energy (DOE) and Lockheed Martin Space Systems Company (LMSSC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. This generator would use two highefficiency Advanced Stirling Convertors (ASCs), developed by Sunpower, Inc., and NASA Glenn Research Center. The ASCs convert thermal energy from a radioisotope heat source into electricity. As part of ground testing of these ASCs, different operating conditions are used to simulate expected mission conditions. These conditions require achieving a particular operating frequency, hot-end and cold-end temperatures, and specified electrical power output for a given heat input. It is difficult to measure heat input to Stirling convertors due to the complex geometries of the hot components, temperature limits of sensor materials, and invasive integration of sensors. A thin-film heat flux sensor was used to directly measure heat input to an ASC. The effort succeeded in designing and fabricating unique sensors, which were integrated into a Stirling convertor ground test and exposed to test temperatures exceeding 700 C in air for 10,000 hr. Sensor measurements were used to calculate thermal efficiency for ASC-E (Engineering Unit) #1 and #4. The post-disassembly condition of the sensors is also discussed.

Advanced Video Guidance Sensor (AVGS) Development Testing

NASA Technical Reports Server (NTRS)

Howard, Richard T.; Johnston, Albert S.; Bryan, Thomas C.; Book, Michael L.

2004-01-01

NASA's Marshall Space Flight Center was the driving force behind the development of the Advanced Video Guidance Sensor, an active sensor system that provides near-range sensor data as part of an automatic rendezvous and docking system. The sensor determines the relative positions and attitudes between the active sensor and the passive target at ranges up to 300 meters. The AVGS uses laser diodes to illuminate retro-reflectors in the target, a solid-state camera to detect the return from the target, and image capture electronics and a digital signal processor to convert the video information into the relative positions and attitudes. The AVGS will fly as part of the Demonstration of Autonomous Rendezvous Technologies (DART) in October, 2004. This development effort has required a great deal of testing of various sorts at every phase of development. Some of the test efforts included optical characterization of performance with the intended target, thermal vacuum testing, performance tests in long range vacuum facilities, EMI/EMC tests, and performance testing in dynamic situations. The sensor has been shown to track a target at ranges of up to 300 meters, both in vacuum and ambient conditions, to survive and operate during the thermal vacuum cycling specific to the DART mission, to handle EM1 well, and to perform well in dynamic situations.

Performance of an Advanced Stirling Convertor Based on Heat Flux Sensor Measurements

NASA Technical Reports Server (NTRS)

Wilson, Scott D.

2012-01-01

The U.S. Department of Energy (DOE) and Lockheed Martin Space Systems Company (LMSSC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. This generator would use two high-efficiency Advanced Stirling Convertors (ASCs), developed by Sunpower, Inc., and NASA Glenn Research Center. The ASCs convert thermal energy from a radioisotope heat source into electricity. As part of ground testing of these ASCs, different operating conditions are used to simulate expected mission conditions. These conditions require achieving a particular operating frequency, hot-end and cold-end temperatures, and specified electrical power output for a given heat input. It is difficult to measure heat input to Stirling convertors due to the complex geometries of the hot components, temperature limits of sensor materials, and invasive integration of sensors. A thin-film heat flux sensor was used to directly measure heat input to an ASC. The effort succeeded in designing and fabricating unique sensors, which were integrated into a Stirling convertor ground test and exposed to test temperatures exceeding 700 C in air for 10,000 hr. Sensor measurements were used to calculate thermal efficiency for ASC-E (Engineering Unit) #1 and #4. The post-disassembly condition of the sensors is also discussed.

Studying the Effect of Deposition Conditions on the Performance and Reliability of MEMS Gas Sensors

PubMed Central

Sadek, Khaled; Moussa, Walied

2007-01-01

In this paper, the reliability of a micro-electro-mechanical system (MEMS)-based gas sensor has been investigated using Three Dimensional (3D) coupled multiphysics Finite Element (FE) analysis. The coupled field analysis involved a two-way sequential electrothermal fields coupling and a one-way sequential thermal-structural fields coupling. An automated substructuring code was developed to reduce the computational cost involved in simulating this complicated coupled multiphysics FE analysis by up to 76 percent. The substructured multiphysics model was then used to conduct a parametric study of the MEMS-based gas sensor performance in response to the variations expected in the thermal and mechanical characteristics of thin films layers composing the sensing MEMS device generated at various stages of the microfabrication process. Whenever possible, the appropriate deposition variables were correlated in the current work to the design parameters, with good accuracy, for optimum operation conditions of the gas sensor. This is used to establish a set of design rules, using linear and nonlinear empirical relations, which can be utilized in real-time at the design and development decision-making stages of similar gas sensors to enable the microfabrication of these sensors with reliable operation.

Smart monolithic integration of inkjet printed thermal flow sensors with fast prototyping polymer microfluidics

NASA Astrophysics Data System (ADS)

Etxebarria, Ikerne; Elizalde, Jorge; Pacios, Roberto

2016-08-01

There is an increasing demand for built-in flow sensors in order to effectively control microfluidic processes due to the high number of available microfluidic applications. The possible solutions should be inexpensive and easy to connect to both, the microscale features and the macro setup. In this paper, we present a novel approach to integrate a printed thermal flow sensor with polymeric microfluidic channels. This approach is focused on merging two high throughput production processes, namely inkjet printing and fast prototyping technologies, in order to produce trustworthy and low cost devices. These two technologies are brought together to obtain a sensor located outside the microfluidic device. This avoids the critical contact between the sensor material and the fluids through the microchannels that can seriously damage the conducting paths under continuous working regimes. In this way, we ensure reliable and stable operation modes. For this application, a silver nanoparticle based ink and cyclic olefin polymer were used. This flow sensor operates linearly in the range of 0-10 μl min-1 for water and 0-20 μl min-1 for ethanol in calorimetric mode. Switching to anemometric mode, the range can be expanded up to 40 μl min-1.

A Current Sensor Based on the Giant Magnetoresistance Effect: Design and Potential Smart Grid Applications

PubMed Central

Ouyang, Yong; He, Jinliang; Hu, Jun; Wang, Shan X.

2012-01-01

Advanced sensing and measurement techniques are key technologies to realize a smart grid. The giant magnetoresistance (GMR) effect has revolutionized the fields of data storage and magnetic measurement. In this work, a design of a GMR current sensor based on a commercial analog GMR chip for applications in a smart grid is presented and discussed. Static, dynamic and thermal properties of the sensor were characterized. The characterizations showed that in the operation range from 0 to ±5 A, the sensor had a sensitivity of 28 mV·A−1, linearity of 99.97%, maximum deviation of 2.717%, frequency response of −1.5 dB at 10 kHz current measurement, and maximum change of the amplitude response of 0.0335%·°C−1 with thermal compensation. In the distributed real-time measurement and monitoring of a smart grid system, the GMR current sensor shows excellent performance and is cost effective, making it suitable for applications such as steady-state and transient-state monitoring. With the advantages of having a high sensitivity, high linearity, small volume, low cost, and simple structure, the GMR current sensor is promising for the measurement and monitoring of smart grids. PMID:23202221

A current sensor based on the giant magnetoresistance effect: design and potential smart grid applications.

PubMed

Ouyang, Yong; He, Jinliang; Hu, Jun; Wang, Shan X

2012-11-09

Advanced sensing and measurement techniques are key technologies to realize a smart grid. The giant magnetoresistance (GMR) effect has revolutionized the fields of data storage and magnetic measurement. In this work, a design of a GMR current sensor based on a commercial analog GMR chip for applications in a smart grid is presented and discussed. Static, dynamic and thermal properties of the sensor were characterized. The characterizations showed that in the operation range from 0 to ±5 A, the sensor had a sensitivity of 28 mV·A(-1), linearity of 99.97%, maximum deviation of 2.717%, frequency response of −1.5 dB at 10 kHz current measurement, and maximum change of the amplitude response of 0.0335%·°C(-1) with thermal compensation. In the distributed real-time measurement and monitoring of a smart grid system, the GMR current sensor shows excellent performance and is cost effective, making it suitable for applications such as steady-state and transient-state monitoring. With the advantages of having a high sensitivity, high linearity, small volume, low cost, and simple structure, the GMR current sensor is promising for the measurement and monitoring of smart grids.

Development of the Kiel sensors for the EPD instrument on-board Solar Orbiter

NASA Astrophysics Data System (ADS)

Martin, Cesar; Wimmer-Schweingruber, Robert F.; Kulkarni, Shrinivasrao R.; Tammen, Jan; Terasa, Christoph; Yu, Jia; Boden, Sebastian; Steinhagen, Jan; Panitzsch, Lauri; Ravanbakhsh, Ali; Boettcher, Stephan; Hamann, Christian; Seimetz, Lars; Rodriguez-Pacheco, Javier

2014-05-01

Solar Orbiter is ESA's next solar and heliospheric mission, planned for launch in January 2017 and approaching the Sun as close as 0.28 AU. One of the Solar Orbiter's scientific questions is "How do the solar eruptions produce energetic particle radiation that fills the heliosphere?". The Energetic Particle Detector (EPD) will provide key measurements for this and the other Solar Orbiter science objectives. The EPD suite consists of four sensors measuring electrons, protons, and ions from helium to iron, and operating at partly overlapping energy ranges from 2 keV/n up to 200 MeV/n. The EPD sensors are: SupraThermal Electrons and Protons(STEP), Suprathermal Ion Spectrograph (SIS), Electron Proton Telescope (EPT) and High Energy Telescope (HET). Besides, the EPD sensors share the Instrument Control Unit (ICU). The University of Kiel in Germany is responsible for developing the EPT-HET, STEP and SIS sensors. Here we present the development status of the EPT-HET and STEP sensors focusing on the activities planned for the current phase C. Those activities include results of the environmental tests on the EPT-HET Structural Thermal Model (STM) and the assembly of the Engineering Model (EM).

The Focal Plane Assembly for the Athena X-Ray Integral Field Unit Instrument

NASA Technical Reports Server (NTRS)

Jackson, B. D.; Van Weers, H.; van der Kuur, J.; den Hartog, R.; Akamatsu, H.; Argan, A.; Bandler, S. R.; Barbera, M.; Barret, D.; Bruijn, M. P.;

MEMS-based thermoelectric infrared sensors: A review

NASA Astrophysics Data System (ADS)

Xu, Dehui; Wang, Yuelin; Xiong, Bin; Li, Tie

2017-12-01

In the past decade, micro-electromechanical systems (MEMS)-based thermoelectric infrared (IR) sensors have received considerable attention because of the advances in micromachining technology. This paper presents a review of MEMS-based thermoelectric IR sensors. The first part describes the physics of the device and discusses the figures of merit. The second part discusses the sensing materials, thermal isolation microstructures, absorber designs, and packaging methods for these sensors and provides examples. Moreover, the status of sensor implementation technology is examined from a historical perspective by presenting findings from the early years to the most recent findings.

Thermal Conductivity Measurement of Liquids by Using a Suspended Microheater

NASA Astrophysics Data System (ADS)

Oh, Dong-Wook

2017-10-01

In this paper, the traditional 3ω method is modified in order to measure the thermal conductivity of a droplet of liquid. The 3ω sensor is microfabricated using bulk silicon etching on a silicon wafer to form a microheater on a suspended bridge structure. The Si substrate of over 400 μ m thickness beneath the microheater is etched away so that the sample liquid can fill the gap created between the heater and the bottom boundary of the sensor. The frequency of the sinusoidal heating pulses that are generated from the heater is controlled such that the thermal penetration depth is much smaller than the thickness of the liquid layer. The temperature oscillation of the sample fluid is measured at the thin-film heater to calculate the thermal conductivity of the surrounding fluid. The thermal conductivity and measured values of the de-ionized water and ethanol show a good agreement with the theoretical values at room temperature.

Rare Earth Optical Temperature Sensor

NASA Technical Reports Server (NTRS)

Chubb, Donald L. (Inventor); Jenkins, Phillip (Inventor)

2004-01-01

A rare earth optical temperature sensor is disclosed for measuring high temperatures. Optical temperature sensors exist that channel emissions from a sensor to a detector using a light pipe. The invention uses a rare earth emitter to transform the sensed thermal energy into a narrow band width optical signal that travels to a detector using a light pipe. An optical bandpass filter at the detector removes any noise signal outside of the band width of the signal from the emitter.

Development of NTD Ge Sensors for Superconducting Bolometer

NASA Astrophysics Data System (ADS)

Garai, A.; Mathimalar, S.; Singh, V.; Dokania, N.; Nanal, V.; Pillay, R. G.; Ramakrishnan, S.; Shrivastava, A.; Jagadeesan, K. C.; Thakare, S. V.

2016-08-01

Neutron transmutation-doped (NTD) Ge sensors have been prepared by irradiating device-grade Ge with thermal neutrons at Dhruva reactor, BARC, Mumbai. These sensors are intended to be used for the study of neutrinoless double beta decay in ^{124}Sn with a superconducting Tin bolometer. Resistance measurements are performed on NTD Ge sensors in the temperature range 100-350 mK. The observed temperature dependence is found to be consistent with the variable-range hopping mechanism.

MISSE-6 Post-Flight Examination, Disassembly and Analysis Results

DTIC Science & Technology

2010-12-21

Wiring, QCM wiring, and Rotor/ Sensor wiring. The data wiring for the Boeing experiments including QCMs and Rotor/ Sensor were labeled, removed, and...for a QCM In addition, Q9 was properly wired into datalogger D8, and the rotor sensor was properly wired into datalogger D9. Datalogger D9 was a...Wiring. Appendix B – Time-Temperature Results from Thermal Sensors distributed on MISSE-6A and MISSE-6B Appendix C - Atomic Oxygen Calculation

Sap flow sensors: construction, quality control and comparison.

PubMed

Davis, Tyler W; Kuo, Chen-Min; Liang, Xu; Yu, Pao-Shan

2012-01-01

This work provides a design for two types of sensors, based on the thermal dissipation and heat ratio methods of sap flow calculation, for moderate to large scale deployments for the purpose of monitoring tree transpiration. These designs include a procedure for making these sensors, a quality control method for the final products, and a complete list of components with vendors and pricing information. Both sensor designs were field tested alongside a commercial sap flow sensor to assess their performance and show the importance for quality controlling the sensor outputs. Results show that for roughly 2% of the cost of commercial sensors, self-made sap flow sensors can provide acceptable estimates of the sap flow measurements compared to the commercial sensors.

Detection mechanism and characteristics of ZnO-based N2O sensors operating with photons

NASA Astrophysics Data System (ADS)

Jeong, T. S.; Yu, J. H.; Mo, H. S.; Kim, T. S.; Youn, C. J.; Hong, K. J.

2013-11-01

N2O sensors made with ZnO-based ZnCdO films were grown on Pyrex substrates by using the RF co-sputtering method. The structure of the N2O sensor was electrode/sensor/glass/illuminant. The mechanism of the photo-assisted oxidation and reduction process on the surface of the N2O sensors was investigated using light from a UV lamp and violet light emitting diode (LED). For photon exposure wavelengths of 365 and 405 nm, the sensitivity of the ZnO-based ZnCdO sensors was measured. From these measurements, the values of the sensitivity of the sensors with x = 0, 0.01, and 0.05 were found to be S = 1.44, 1.39, and 1.33 under LED light with a wavelength of 405 nm, respectively. These sensitivities were compared to those of SnO2 and WO3 materials measured at operating temperatures of 300-600 °C. Also, under exposure with UV light, the response times were observed to be 130 to 270 sec. These response times were slightly slower than that for the traditional method of thermal heating. However, they indicate that the described photon exposure method for N2O detection can replace the conventional heating mode. Consequently, we demonstrated that portable N2O sensors for room-temperature operation could be fabricated without thermal heating.

Cr2O3 nanoparticle-functionalized WO3 nanorods for ethanol gas sensors

NASA Astrophysics Data System (ADS)

Choi, Seungbok; Bonyani, Maryam; Sun, Gun-Joo; Lee, Jae Kyung; Hyun, Soong Keun; Lee, Chongmu

2018-02-01

Pristine WO3 nanorods and Cr2O3-functionalized WO3 nanorods were synthesized by the thermal evaporation of WO3 powder in an oxidizing atmosphere, followed by spin-coating of the nanowires with Cr2O3 nanoparticles and thermal annealing in an oxidizing atmosphere. Scanning electron microscopy was used to examine the morphological features and X-ray diffraction was used to study the crystallinity and phase formation of the synthesized nanorods. Gas sensing tests were performed at different temperatures in the presence of test gases (ethanol, acetone, CO, benzene and toluene). The Cr2O3-functionalized WO3 nanorods sensor showed a stronger response to these gases relative to the pristine WO3 nanorod sensor. In particular, the response of the Cr2O3-functionalized WO3 nanorods sensor to 200 ppm ethanol gas was 5.58, which is approximately 4.4 times higher that of the pristine WO3 nanorods sensor. Furthermore, the Cr2O3-functionalized WO3 nanorods sensor had a shorter response and recovery time. The pristine WO3 nanorods had no selectivity toward ethanol gas, whereas the Cr2O3-functionalized WO3 nanorods sensor showed good selectivity toward ethanol. The gas sensing mechanism of the Cr2O3-functionalized WO3 nanorods sensor toward ethanol is discussed in detail.

Measurement of Thermal Properties of Rocks at Temperature up to 1,000°C with Transient Plane Source Techniques

NASA Astrophysics Data System (ADS)

Kim, S. K.; Lee, Y.

2017-12-01

A set of devices that can measure thermal properties of rocks over a temperature range from room temperature up to 1,000°C with transient plane source techniques (also known as a Hot Disk method) is introduced. It consists of a main control system (e.g., TPS 2500 S from Hot Disk), mica-insulated sensor, tubular furnace, N2 gas supplier, and pressure regulator. The TPS 2500 S is the core instrument designed for precise analysis of thermal transport properties including thermal conductivity, thermal diffusivity, and volumetric heat capacity. The mica-insulated sensor is composed of an insulated nickel double spiral, which is utilized for both transient heating and precise temperature reading; a mica insulator protects the sensor against mechanical and thermal damage at high temperatures. The tubular furnace can hold two rock core samples of 50-mm-diameter and 25-mm-height with increasing temperatures up to 1,000°C. N2 gas supplier and pressure regulator are used to keep the inside the furnace away from oxygen. Thermal properties of most rocks and minerals vary with increasing temperatures. Experimental measurements of thermal properties at high temperatures have been made mostly using laser flash, needle probe, and divided bar methods in the previous researches, and no previous measurements with the Hot Disk method have been reported yet. We report thermal conductivities, thermal diffusivities, and volumetric heat capacities determined by a transient plane heat source method for fused silica and mafic rock samples using the introduced transient plane source apparatus. The thermal properties of fused silica have been measured mainly over the temperature range from ambient temperature to 500°C. The results seem to agree moderately with the previously reported values by Birch and Clark (Am. J. Sci., 1940). We now check the possible causes of measurement errors in our measurements and prepare to measure thermal properties of the mafic rock samples at temperatures up to 1,000°C using the hot disk method.

Temperature and heat flux measurements: Challenges for high temperature aerospace application

NASA Technical Reports Server (NTRS)

Neumann, Richard D.

1992-01-01

The measurement of high temperatures and the influence of heat transfer data is not strictly a problem of either the high temperatures involved or the level of the heating rates to be measured at those high temperatures. It is a problem of duration during which measurements are made and the nature of the materials in which the measurements are made. Thermal measurement techniques for each application must respect and work with the unique features of that application. Six challenges in the development of measurement technology are discussed: (1) to capture the character and localized peak values within highly nonuniform heating regions; (2) to manage large volumes of thermal instrumentation in order to efficiently derive critical information; (3) to accommodate thermal sensors into practical flight structures; (4) to broaden the capabilities of thermal survey techniques to replace discrete gages in flight and on the ground; (5) to provide supporting instrumentation conduits which connect the measurement points to the thermally controlled data acquisition system; and (6) to develop a class of 'vehicle tending' thermal sensors to assure the integrity of flight vehicles in an efficient manner.

Dynamic Electrothermal Model of a Sputtered Thermopile Thermal Radiation Detector for Earth Radiation Budget Applications

NASA Technical Reports Server (NTRS)

Weckmann, Stephanie

1997-01-01

The Clouds and the Earth's Radiant Energy System (CERES) is a program sponsored by the National Aeronautics and Space Administration (NASA) aimed at evaluating the global energy balance. Current scanning radiometers used for CERES consist of thin-film thermistor bolometers viewing the Earth through a Cassegrain telescope. The Thermal Radiation Group, a laboratory in the Department of Mechanical Engineering at Virginia Polytechnic Institute and State University, is currently studying a new sensor concept to replace the current bolometer: a thermopile thermal radiation detector. This next-generation detector would consist of a thermal sensor array made of thermocouple junction pairs, or thermopiles. The objective of the current research is to perform a thermal analysis of the thermopile. Numerical thermal models are particularly suited to solve problems for which temperature is the dominant mechanism of the operation of the device (through the thermoelectric effect), as well as for complex geometries composed of numerous different materials. Feasibility and design specifications are studied by developing a dynamic electrothermal model of the thermopile using the finite element method. A commercial finite element-modeling package, ALGOR, is used.

A low cost surface plasmon resonance biosensor using a laser line generator

NASA Astrophysics Data System (ADS)

Chen, Ruipeng; Wang, Manping; Wang, Shun; Liang, Hao; Hu, Xinran; Sun, Xiaohui; Zhu, Juanhua; Ma, Liuzheng; Jiang, Min; Hu, Jiandong; Li, Jianwei

2015-08-01

Due to the instrument designed by using a common surface plasmon resonance biosensor is extremely expensive, we established a portable and cost-effective surface plasmon resonance biosensing system. It is mainly composed of laser line generator, P-polarizer, customized prism, microfluidic cell, and line Charge Coupled Device (CCD) array. Microprocessor PIC24FJ128GA006 with embedded A/D converter, communication interface circuit and photoelectric signal amplifier circuit are used to obtain the weak signals from the biosensing system. Moreover, the line CCD module is checked and optimized on the number of pixels, pixels dimension, output amplifier and the timing diagram. The micro-flow cell is made of stainless steel with a high thermal conductivity, and the microprocessor based Proportional-Integral-Derivative (PID) temperature-controlled algorithm was designed to keep the constant temperature (25 °C) of the sample solutions. Correspondingly, the data algorithms designed especially to this biosensing system including amplitude-limiting filtering algorithm, data normalization and curve plotting were programmed efficiently. To validate the performance of the biosensor, ethanol solution samples at the concentrations of 5%, 7.5%, 10%, 12.5% and 15% in volumetric fractions were used, respectively. The fitting equation ΔRU = - 752987.265 + 570237.348 × RI with the R-Square of 0.97344 was established by delta response units (ΔRUs) to refractive indexes (RI). The maximum relative standard deviation (RSD) of 4.8% was obtained.

Applications of TIMS data in agricultural areas and related atmospheric considerations

NASA Technical Reports Server (NTRS)

Pelletier, R. E.; Ochoa, M. C.

1986-01-01

While much of traditional remote sensing in agricultural research was limited to the visible and reflective infrared, advances in thermal infrared remote sensing technology are adding a dimension to digital image analysis of agricultural areas. The Thermal Infrared Multispectral Scanner (TIMS) an airborne sensor having six bands over the nominal 8.2 to 12.2 m range, offers the ability to calculate land surface emissivities unlike most previous singular broadband sensors. Preliminary findings on the utility of the TIMS for several agricultural applications and related atmospheric considerations are discussed.

Discrimination techniques employing both reflective and thermal multispectral signals. [for remote sensor technology

NASA Technical Reports Server (NTRS)

Malila, W. A.; Crane, R. B.; Richardson, W.

1973-01-01

Recent improvements in remote sensor technology carry implications for data processing. Multispectral line scanners now exist that can collect data simultaneously and in registration in multiple channels at both reflective and thermal (emissive) wavelengths. Progress in dealing with two resultant recognition processing problems is discussed: (1) More channels mean higher processing costs; to combat these costs, a new and faster procedure for selecting subsets of channels has been developed. (2) Differences between thermal and reflective characteristics influence recognition processing; to illustrate the magnitude of these differences, some explanatory calculations are presented. Also introduced, is a different way to process multispectral scanner data, namely, radiation balance mapping and related procedures. Techniques and potentials are discussed and examples presented.

Frostless heat pump having thermal expansion valves

DOEpatents

Chen, Fang C [Knoxville, TN; Mei, Viung C [Oak Ridge, TN

2002-10-22

A heat pump system having an operable relationship for transferring heat between an exterior atmosphere and an interior atmosphere via a fluid refrigerant and further having a compressor, an interior heat exchanger, an exterior heat exchanger, a heat pump reversing valve, an accumulator, a thermal expansion valve having a remote sensing bulb disposed in heat transferable contact with the refrigerant piping section between said accumulator and said reversing valve, an outdoor temperature sensor, and a first means for heating said remote sensing bulb in response to said outdoor temperature sensor thereby opening said thermal expansion valve to raise suction pressure in order to mitigate defrosting of said exterior heat exchanger wherein said heat pump continues to operate in a heating mode.

In-motion, non-contact rail temperature measurement sensor.

DOT National Transportation Integrated Search

2012-12-01

Preventing track buckling incidents (Figure 1) is important to the railroad industry. Track materials, rail steel, for example, experience thermal expansion, which refers to the increase in a materials volume as its temperature rises. Thermal expa...

Ultrathin Injectable Sensors of Temperature, Thermal Conductivity, and Heat Capacity for Cardiac Ablation Monitoring

PubMed Central

Koh, Ahyeon; Gutbrod, Sarah R.; Meyers, Jason D.; Lu, Chaofeng; Webb, Richard Chad; Shin, Gunchul; Li, Yuhang; Kang, Seung-Kyun; Huang, Yonggang

2016-01-01

Knowledge of the distributions of temperature in cardiac tissue during and after ablation is important in advancing a basic understanding of this process, and for improving its efficacy in treating arrhythmias. Technologies that enable real-time temperature detection and thermal characterization in the transmural direction can help to predict the depths and sizes of lesion that form. Herein, materials and designs for an injectable device platform that supports precision sensors of temperature and thermal transport properties distributed along the length of an ultrathin and flexible needle-type polymer substrate are introduced. The resulting system can insert into the myocardial tissue, in a minimally invasive manner, to monitor both radiofrequency ablation and cryoablation, in a manner that has no measurable effects on the natural mechanical motions of the heart. The measurement results exhibit excellent agreement with thermal simulations, thereby providing improved insights into lesion transmurality. PMID:26648177

Computational fluid dynamic (CFD) investigation of thermal uniformity in a thermal cycling based calibration chamber for MEMS

NASA Astrophysics Data System (ADS)

Gui, Xulong; Luo, Xiaobing; Wang, Xiaoping; Liu, Sheng

2015-12-01

Micro-electrical-mechanical system (MEMS) has become important for many industries such as automotive, home appliance, portable electronics, especially with the emergence of Internet of Things. Volume testing with temperature compensation has been essential in order to provide MEMS based sensors with repeatability, consistency, reliability, and durability, but low cost. Particularly, in the temperature calibration test, temperature uniformity of thermal cycling based calibration chamber becomes more important for obtaining precision sensors, as each sensor is different before the calibration. When sensor samples are loaded into the chamber, we usually open the door of the chamber, then place fixtures into chamber and mount the samples on the fixtures. These operations may affect temperature uniformity in the chamber. In order to study the influencing factors of sample-loading on the temperature uniformity in the chamber during calibration testing, numerical simulation work was conducted first. Temperature field and flow field were simulated in empty chamber, chamber with open door, chamber with samples, and chamber with fixtures, respectively. By simulation, it was found that opening chamber door, sample size and number of fixture layers all have effects on flow field and temperature field. By experimental validation, it was found that the measured temperature value was consistent with the simulated temperature value.

Thermal Analyzer for Planetary Soil (TAPS): an in Situ Instrument for Mineral and Volatile-element Measurements

NASA Technical Reports Server (NTRS)

Gooding, J. L.; Ming, D. W.; Gruener, J. E.; Gibbons, F. L.; Allton, J. H.

1993-01-01

Thermal Analyzer for Planetary Soil (TAPS) offers a specific implementation for the generic thermal analyzer/evolved-gas analyzer (TA/EGA) function included in the Mars Environmental Survey (MESUR) strawman payload; applications to asteroids and comets are also possible. The baseline TAPS is a single-sample differential scanning calorimeter (DSC), backed by a capacitive-polymer humidity sensor, with an integrated sampling mechanism. After placement on a planetary surface, TAPS acquires 10-50 mg of soil or sediment and heats the sample from ambient temperature to 1000-1300 K. During heating, DSC data are taken for the solid and evolved gases are swept past the water sensor. Through ground based data analysis, multicomponent DSC data are deconvolved and correlated with the water release profile to quantitatively determine the types and relative proportions of volatile-bearing minerals such as clays and other hydrates, carbonates, and nitrates. The rapid-response humidity sensors also achieve quantitative analysis of total water. After conclusion of soil-analysis operations, the humidity sensors become available for meteorology. The baseline design fits within a circular-cylindrical volume less than 1000 cm(sup 3), occupies 1.2 kg mass, and consumes about 2 Whr of power per analysis. Enhanced designs would acquire and analyze multiple samples and employ additional microchemical sensors for analysis of CO2, SO2, NO(x), and other gaseous species. Atmospheric pumps are also being considered as alternatives to pressurized purge gas.

Thermal Analyzer for Planetary Soil (TAPS): an in situ instrument for mineral and volatile-element measurements

NASA Astrophysics Data System (ADS)

Gooding, J. L.; Ming, D. W.; Gruener, J. E.; Gibbons, F. L.; Allton, J. H.

Thermal Analyzer for Planetary Soil (TAPS) offers a specific implementation for the generic thermal analyzer/evolved-gas analyzer (TA/EGA) function included in the Mars Environmental Survey (MESUR) strawman payload; applications to asteroids and comets are also possible. The baseline TAPS is a single-sample differential scanning calorimeter (DSC), backed by a capacitive-polymer humidity sensor, with an integrated sampling mechanism. After placement on a planetary surface, TAPS acquires 10-50 mg of soil or sediment and heats the sample from ambient temperature to 1000-1300 K. During heating, DSC data are taken for the solid and evolved gases are swept past the water sensor. Through ground based data analysis, multicomponent DSC data are deconvolved and correlated with the water release profile to quantitatively determine the types and relative proportions of volatile-bearing minerals such as clays and other hydrates, carbonates, and nitrates. The rapid-response humidity sensors also achieve quantitative analysis of total water. After conclusion of soil-analysis operations, the humidity sensors become available for meteorology. The baseline design fits within a circular-cylindrical volume less than 1000 cm3, occupies 1.2 kg mass, and consumes about 2 Whr of power per analysis. Enhanced designs would acquire and analyze multiple samples and employ additional microchemical sensors for analysis of CO2, SO2, NO(x), and other gaseous species. Atmospheric pumps are also being considered as alternatives to pressurized purge gas.

Nonequilibrium diffusive gas dynamics: Poiseuille microflow

NASA Astrophysics Data System (ADS)

Abramov, Rafail V.; Otto, Jasmine T.

2018-05-01

We test the recently developed hierarchy of diffusive moment closures for gas dynamics together with the near-wall viscosity scaling on the Poiseuille flow of argon and nitrogen in a one micrometer wide channel, and compare it against the corresponding Direct Simulation Monte Carlo computations. We find that the diffusive regularized Grad equations with viscosity scaling provide the most accurate approximation to the benchmark DSMC results. At the same time, the conventional Navier-Stokes equations without the near-wall viscosity scaling are found to be the least accurate among the tested closures.

Selective C(sp3)−H Aerobic Oxidation Enabled by Decatungstate Photocatalysis in Flow

PubMed Central

Laudadio, Gabriele; Govaerts, Sebastian; Wang, Ying; Ravelli, Davide; Koolman, Hannes F.; Fagnoni, Maurizio; Djuric, Stevan W.

2018-01-01

Abstract A mild and selective C(sp3)−H aerobic oxidation enabled by decatungstate photocatalysis has been developed. The reaction can be significantly improved in a microflow reactor enabling the safe use of oxygen and enhanced irradiation of the reaction mixture. Our method allows for the oxidation of both activated and unactivated C−H bonds (30 examples). The ability to selectively oxidize natural scaffolds, such as (−)‐ambroxide, pregnenolone acetate, (+)‐sclareolide, and artemisinin, exemplifies the utility of this new method. PMID:29451725

The Thermal Infrared Sensor on the Landsat Data Continutiy Mission

USDA-ARS?s Scientific Manuscript database

The REGularized canopy reFLECtance (REGFLEC) modeling tool integrates leaf optics, canopy reflectance, and atmospheric radiative transfer model components, facilitating accurate retrieval of leaf area index (LAI) and leaf chlorophyll content (Cab) directly from at-sensor radiances in green, red and ...

Augmented Method to Improve Thermal Data for the Figure Drift Thermal Distortion Predictions of the JWST OTIS Cryogenic Vacuum Test

NASA Technical Reports Server (NTRS)

Park, Sang C.; Carnahan, Timothy M.; Cohen, Lester M.; Congedo, Cherie B.; Eisenhower, Michael J.; Ousley, Wes; Weaver, Andrew; Yang, Kan

2017-01-01

The JWST Optical Telescope Element (OTE) assembly is the largest optically stable infrared-optimized telescope currently being manufactured and assembled, and is scheduled for launch in 2018. The JWST OTE, including the 18 segment primary mirror, secondary mirror, and the Aft Optics Subsystem (AOS) are designed to be passively cooled and operate near 45K. These optical elements are supported by a complex composite backplane structure. As a part of the structural distortion model validation efforts, a series of tests are planned during the cryogenic vacuum test of the fully integrated flight hardware at NASA JSC Chamber A. The successful ends to the thermal-distortion phases are heavily dependent on the accurate temperature knowledge of the OTE structural members. However, the current temperature sensor allocations during the cryo-vac test may not have sufficient fidelity to provide accurate knowledge of the temperature distributions within the composite structure. A method based on an inverse distance relationship among the sensors and thermal model nodes was developed to improve the thermal data provided for the nanometer scale WaveFront Error (WFE) predictions. The Linear Distance Weighted Interpolation (LDWI) method was developed to augment the thermal model predictions based on the sparse sensor information. This paper will encompass the development of the LDWI method using the test data from the earlier pathfinder cryo-vac tests, and the results of the notional and as tested WFE predictions from the structural finite element model cases to characterize the accuracies of this LDWI method.

Feasibility Study of LANDSAT-8 Imagery for Retrieving Sea Surface Temperature (case Study Persian Gulf)

NASA Astrophysics Data System (ADS)

Bayat, F.; Hasanlou, M.

2016-06-01

Sea surface temperature (SST) is one of the critical parameters in marine meteorology and oceanography. The SST datasets are incorporated as conditions for ocean and atmosphere models. The SST needs to be investigated for various scientific phenomenon such as salinity, potential fishing zone, sea level rise, upwelling, eddies, cyclone predictions. On the other hands, high spatial resolution SST maps can illustrate eddies and sea surface currents. Also, near real time producing of SST map is suitable for weather forecasting and fishery applications. Therefore satellite remote sensing with wide coverage of data acquisition capability can use as real time tools for producing SST dataset. Satellite sensor such as AVHRR, MODIS and SeaWIFS are capable of extracting brightness values at different thermal spectral bands. These brightness temperatures are the sole input for the SST retrieval algorithms. Recently, Landsat-8 successfully launched and accessible with two instruments on-board: (1) the Operational Land Imager (OLI) with nine spectral bands in the visual, near infrared, and the shortwave infrared spectral regions; and (2) the Thermal Infrared Sensor (TIRS) with two spectral bands in the long wavelength infrared. The two TIRS bands were selected to enable the atmospheric correction of the thermal data using a split window algorithm (SWA). The TIRS instrument is one of the major payloads aboard this satellite which can observe the sea surface by using the split-window thermal infrared channels (CH10: 10.6 μm to 11.2 μm; CH11: 11.5 μm to 12.5 μm) at a resolution of 30 m. The TIRS sensors have three main advantages comparing with other previous sensors. First, the TIRS has two thermal bands in the atmospheric window that provide a new SST retrieval opportunity using the widely used split-window (SW) algorithm rather than the single channel method. Second, the spectral filters of TIRS two bands present narrower bandwidth than that of the thermal band on board on previous Landsat sensors. Third, TIRS is one of the best space born and high spatial resolution with 30 m. in this regards, Landsat-8 can use the Split-Window (SW) algorithm for retrieving SST dataset. Although several SWs have been developed to use with other sensors, some adaptations are required in order to implement them for the TIRS spectral bands. Therefore, the objective of this paper is to develop a SW, adapted for use with Landsat-8 TIRS data, along with its accuracy assessment. In this research, that has been done for modelling SST using thermal Landsat 8-imagery of the Persian Gulf. Therefore, by incorporating contemporary in situ data and SST map estimated from other sensors like MODIS, we examine our proposed method with coefficient of determination (R2) and root mean square error (RMSE) on check point to model SST retrieval for Landsat-8 imagery. Extracted results for implementing different SW's clearly shows superiority of utilized method by R2 = 0.95 and RMSE = 0.24.

Low frequency seismic noise acquisition and analysis with tunable monolithic horizontal sensors

NASA Astrophysics Data System (ADS)

Acernese, Fausto; De Rosa, Rosario; Giordano, Gerardo; Romano, Rocco; Vilasi, Silvia; Barone, Fabrizio

2011-04-01

In this paper we describe the scientific data recorded mechanical monolithic horizontal sensor prototypes located in the Gran Sasso Laboratory of the INFN. The mechanical monolithic sensors, developed at the University of Salerno, are placed, in thermally insulating enclosures, onto concrete slabs connected to the bedrock. The main goal of this experiment is to characterize seismically the sites in the frequency band 10-4 ÷ 10Hz and to get all the necessary information to optimize the sensor.

The DMSP Space Weather Sensors Data Archive Listing (1982-2013) and File Formats Descriptions

DTIC Science & Technology

2014-08-01

environment sensors including the auroral particle spectrometer (SSJ), the fluxgate magnetometer (SSM), the topside thermal plasma monitor (SSIES... Fluxgate Magnetometer (SSM) for the Defense Meteorological Satellite Program (DMSP) Block 5D-2, Flight 7, Instrument Papers, AFGL-TR-84-0225; ADA155229...Flux) SSM The fluxgate magnetometer . (Special Sensor, Magnetometer ) SSULI The ultraviolet limb imager SSUSI The ultraviolet spectrographic imager

Application of airborne thermal imagery to surveys of Pacific walrus

USGS Publications Warehouse

Burn, D.M.; Webber, M.A.; Udevitz, M.S.

2006-01-01

We conducted tests of airborne thermal imagery of Pacific walrus to determine if this technology can be used to detect walrus groups on sea ice and estimate the number of walruses present in each group. In April 2002 we collected thermal imagery of 37 walrus groups in the Bering Sea at spatial resolutions ranging from 1-4 m. We also collected high-resolution digital aerial photographs of the same groups. Walruses were considerably warmer than the background environment of ice, snow, and seawater and were easily detected in thermal imagery. We found a significant linear relation between walrus group size and the amount of heat measured by the thermal sensor at all 4 spatial resolutions tested. This relation can be used in a double-sampling framework to estimate total walrus numbers from a thermal survey of a sample of units within an area and photographs from a subsample of the thermally detected groups. Previous methods used in visual aerial surveys of Pacific walrus have sampled only a small percentage of available habitat, resulting in population estimates with low precision. Results of this study indicate that an aerial survey using a thermal sensor can cover as much as 4 times the area per hour of flight time with greater reliability than visual observation.

Temperature insensitive refractive index sensor based on concatenated long period fiber gratings

NASA Astrophysics Data System (ADS)

Tripathi, Saurabh M.; Bock, Wojtek J.; Mikulic, Predrag

2013-10-01

We propose and demonstrate a temperature immune biosensor based on two concatenated LPGs incorporating a suitable inter-grating-space (IGS). Compensating the thermal induced phase changes in the grating region by use of an appropriate length of the IGS the temperature insensitivity has been achieved. Using standard telecommunication grade single-mode fibers we show that a length ratio of ~8.2 is sufficient to realize the proposed temperature insensitivity. The resulting sensor shows a refractive index sensitivity of 423.28 nm/RIU displaying the capability of detecting an index variation of 2.36 × 10-6 RIU in the bio-samples. The sensor can also be applied as a temperature insensitive WMD channel isolation filter in the optical communication systems, removing the necessity of any external thermal insulation packaging.

Development of heat flux sensors for turbine airfoils and combustor liners

NASA Astrophysics Data System (ADS)

Atkinson, W. H.

1983-10-01

The design of durable turbine airfoils that use a minimum amount of cooling air requires knowledge of the heat loads on the airfoils during engine operation. Measurement of these heat loads will permit the verification or modification of the analytical models used in the design process and will improve the ability to predict and confirm the thermal performance of turbine airfoil designs. Heat flux sensors for turbine blades and vanes must be compatible with the cast nickel-base and cobalt-base materials used in their fabrication and will need to operate in a hostile environment with regard to temperature, pressure and thermal cycling. There is also a need to miniaturize the sensors to obtain measurements without perturbing the heat flows that are to be measured.

Calibration of the Thermal Infrared Sensor on the Landsat Data Continuity Mission

NASA Technical Reports Server (NTRS)

Thome, K; Reuter, D.; Lunsford, D.; Montanaro, M.; Smith, J.; Tesfaye, Z.; Wenny, B.

2011-01-01

The Landsat series of satellites provides the longest running continuous data set of moderate-spatial-resolution imagery beginning with the launch of Landsat 1 in 1972 and continuing with the 1999 launch of Landsat 7 and current operation of Landsats 5 and 7. The Landsat Data Continuity Mission (LDCM) will continue this program into a fourth decade providing data that are keys to understanding changes in land-use changes and resource management. LDCM consists of a two-sensor platform comprised of the Operational Land Imager (OLI) and Thermal Infrared Sensors (TIRS). A description of the applications and design of the TIRS instrument is given as well as the plans for calibration and characterization. Included are early results from preflight calibration and a description of the inflight validation.

Method for measuring thermal accommodation coefficients of gases on thin film surfaces using a MEMS sensor structure

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

Grau, Mario, E-mail: mario.grau@hs-rm.de; Völklein, Friedemann; Meier, Andreas

A method for measuring the thermal accommodation coefficient α for surface-/gas interfaces is presented. It allows the determination of α for thin films produced by a variety of deposition technologies, such as chemical vapor deposition, physical vapor deposition, and atomic layer deposition (ALD). The setup is based on two microelectromechanical systems (MEMS) Pirani sensors facing each other in a defined positioning. Because these MEMS sensors show a very high sensitivity in their individual molecular flow regimes, it is possible to measure the accommodation coefficients of gases without the disturbing influence of the transition regime. This paper presents the analytical backgroundmore » and the actual measurement principle. The results for air and nitrogen molecules on sputtered Au and Pt surfaces are presented.« less

Phase Retrieval on Undersampled Data from the Thermal Infrared Sensor (TIRS)

NASA Technical Reports Server (NTRS)

Bolcar, Matthew R.; Mentzell, Eric

2011-01-01

Phase retrieval was applied to under-sampled data from a thermal infrared imaging system to estimate defocus across the field of view (FOV). We compare phase retrieval estimated values to those obtained using an independent technique.

A study of selected environmental quality remote sensors for free flyer missions launched from the space shuttle

NASA Technical Reports Server (NTRS)

Goldstein, H. W.; Grenda, R. N.

1977-01-01

The sensors were examined for adaptability to shuttle by reviewing pertinent information regarding sensor characteristics as they related to the shuttle and Multimission Modular Spacecraft environments. This included physical and electrical characteristics, data output and command requirements, attitude and orientation requirements, thermal and safety requirements, and adaptability and modification for space. The sensor requirements and characteristics were compared with the corresponding shuttle and Multimission Modular Spacecraft characteristics and capabilities. On this basis the adaptability and necessary modifications for each sensor were determined. A number of the sensors were examined in more detail and estimated cost for the modifications was provided.

Characterizing the Diurnal Cycle of Land Surface Temperature and Evapotranspiration at High Spatial Resolution Using Thermal Observations from sUAS.

NASA Astrophysics Data System (ADS)

Dutta, D.; Drewry, D.; Johnson, W. R.

2017-12-01

The surface temperature of plant canopies is an important indicator of the stomatal regulation of plant water use and the associated water flux from plants to atmosphere (evapotranspiration (ET)). Remotely sensed thermal observations using compact, low-cost, lightweight sensors from small unmanned aerial systems (sUAS) have the potential to provide surface temperature (ST) and ET estimates at unprecedented spatial and temporal resolutions, allowing us to characterize the intra-field diurnal variations in canopy ST and ET for a variety of vegetation systems. However, major challenges exist for obtaining accurate surface temperature estimates from low-cost uncooled microbolometer-type sensors. Here we describe the development of calibration methods using thermal chamber experiments, taking into account the ambient optics and sensor temperatures, and applying simple models of spatial non-uniformity correction to the sensor focal-plane-array. We present a framework that can be used to derive accurate surface temperatures using radiometric observations from low-cost sensors, and demonstrate this framework using a sUAS-mounted sensor across a diverse set of calibration and vegetation targets. Further, we demonstrate the use of the Surface Temperature Initiated Closure (STIC) model for computing spatially explicit, high spatial resolution ET estimates across several well-monitored agricultural systems, as driven by sUAS acquired surface temperatures. STIC provides a physically-based surface energy balance framework for the simultaneous retrieval of the surface and atmospheric vapor conductances and surface energy fluxes, by physically integrating radiometric surface temperature information into the Penman-Monteith equation. Results of our analysis over agricultural systems in Ames, IA and Davis, CA demonstrate the power of this approach for quantifying the intra-field spatial variability in the diurnal cycle of plant water use at sub-meter resolutions.

An airborne thematic thermal infrared and electro-optical imaging system

NASA Astrophysics Data System (ADS)

Sun, Xiuhong; Shu, Peter

2011-08-01

This paper describes an advanced Airborne Thematic Thermal InfraRed and Electro-Optical Imaging System (ATTIREOIS) and its potential applications. ATTIREOIS sensor payload consists of two sets of advanced Focal Plane Arrays (FPAs) - a broadband Thermal InfraRed Sensor (TIRS) and a four (4) band Multispectral Electro-Optical Sensor (MEOS) to approximate Landsat ETM+ bands 1,2,3,4, and 6, and LDCM bands 2,3,4,5, and 10+11. The airborne TIRS is 3-axis stabilized payload capable of providing 3D photogrammetric images with a 1,850 pixel swathwidth via pushbroom operation. MEOS has a total of 116 million simultaneous sensor counts capable of providing 3 cm spatial resolution multispectral orthophotos for continuous airborne mapping. ATTIREOIS is a complete standalone and easy-to-use portable imaging instrument for light aerial vehicle deployment. Its miniaturized backend data system operates all ATTIREOIS imaging sensor components, an INS/GPS, and an e-Gimbal™ Control Electronic Unit (ECU) with a data throughput of 300 Megabytes/sec. The backend provides advanced onboard processing, performing autonomous raw sensor imagery development, TIRS image track-recovery reconstruction, LWIR/VNIR multi-band co-registration, and photogrammetric image processing. With geometric optics and boresight calibrations, the ATTIREOIS data products are directly georeferenced with an accuracy of approximately one meter. A prototype ATTIREOIS has been configured. Its sample LWIR/EO image data will be presented. Potential applications of ATTIREOIS include: 1) Providing timely and cost-effective, precisely and directly georeferenced surface emissive and solar reflective LWIR/VNIR multispectral images via a private Google Earth Globe to enhance NASA's Earth science research capabilities; and 2) Underflight satellites to support satellite measurement calibration and validation observations.

Evaluation of the lubrication mechanism at various rotation speeds and granule filling levels in a container mixer using a thermal effusivity sensor.

PubMed

Uchiyama, Jumpei; Aoki, Shigeru

2015-01-01

To research the detailed mechanism of the lubrication process using the thermal effusivity sensor, the relationships of the lubrication progress with the pattern of powder flow, the rotation speed and the filling level were investigated. The thermal effusivity profile was studied as a function of the number of rotations at various rotation speeds. It was observed that at lower rotation speeds, the profiles of the lubrication progress were almost the same, regardless of the rotation speed. In this region, the highest speed was defined as the critical rotation speed (CRS), which was found to be one of the important factors. The CRS had close relations with avalanche flow in the blender. The first and the second phases were observed in the lubrication process. The first phase was influenced by the CRS and the filling level in the blender. The second phase was influenced by the rotation speed. The mechanism of two-phase process was proposed as a macro progression of the dispersion of the lubricant (first phase) and micro progression of the coating of the powder particles with lubricant (second phase). The accurate monitoring by the thermal effusivity sensor was able to help a better understanding in the lubrication process.

Radiative transfer model for aerosols at infrared wavelengths for passive remote sensing applications: revisited.

PubMed

Ben-David, Avishai; Davidson, Charles E; Embury, Janon F

2008-11-01

We introduced a two-dimensional radiative transfer model for aerosols in the thermal infrared [Appl. Opt.45, 6860-6875 (2006)APOPAI0003-693510.1364/AO.45.006860]. In that paper we superimposed two orthogonal plane-parallel layers to compute the radiance due to a two-dimensional (2D) rectangular aerosol cloud. In this paper we revisit the model and correct an error in the interaction of the two layers. We derive new expressions relating to the signal content of the radiance from an aerosol cloud based on the concept of five directional thermal contrasts: four for the 2D diffuse radiance and one for direct radiance along the line of sight. The new expressions give additional insight on the radiative transfer processes within the cloud. Simulations for Bacillus subtilis var. niger (BG) bioaerosol and dustlike kaolin aerosol clouds are compared and contrasted for two geometries: an airborne sensor looking down and a ground-based sensor looking up. Simulation results suggest that aerosol cloud detection from an airborne platform may be more challenging than for a ground-based sensor and that the detection of an aerosol cloud in emission mode (negative direct thermal contrast) is not the same as the detection of an aerosol cloud in absorption mode (positive direct thermal contrast).

Fiber optic and laser sensors X; Proceedings of the Meeting, Boston, MA, Sept. 8-11, 1992

NASA Technical Reports Server (NTRS)

Udd, Eric (Editor); Depaula, Ramon P. (Editor)

1993-01-01

Topics addressed include acoustic and pressure sensors; fiber optic gyros; electric and magnetic field sensors; bend, strain, and temperature sensors; industrial applications of sensors; and processing techniques. Particular attention is given to fiber optic interferometric acoustic sensors for wind tunnel applications, polished coupler and resonator fabrication, second-harmonic detection for rotation sensing in fiber optic gyros, simplified control theory in closed-loop fiber optic gyroscopes, and a Fabry-Perot sensor with digital signal processing for the measurement of magnetostriction. Also discussed are a Bragg fiber laser sensor, commercialization of fiber optic strain gauge systems, thermal ignition in hazardous environments due to stray light from optical fibers, a system for absolute measurements by interferometric sensors, and high-performance interferometric demodulation techniques.

Geologic remote sensing study of the Hayden pass-Orient Mine Area, Northern Sangre de Cristo Mountains, Colorado

NASA Technical Reports Server (NTRS)

Wychgram, D. C.

1972-01-01

Remote sensor data from a NASA Convair 990 radar flight and Mission 101 and 105 have been interpreted and evaluated. Based on interpretation of the remote sensor data, a geologic map has been prepared and compared with a second geologic map, prepared from interpretation of both remote sensor data and field data. Comparison of the two maps gives one indication of the usefulness and reliability of the remote sensor data. Color and color infrared photography provided the largest amount of valuable information. Multiband photography was of lesser value and side-looking radar imagery provided no new information that was not available on small scale photography. Thermal scanner imagery proved to be a very specialized remote sensing tool that should be applied to areas of low relief and sparse vegetation where geologic features produce known or suspected thermal contrast. Low sun angle photography may be a good alternative to side-looking radar imagery but must be flown with critical timing.

A Novel Thermal Sensor for the Sensitive Measurement of Chemical Oxygen Demand

PubMed Central

Yao, Na; Liu, Zhuan; Chen, Ying; Zhou, Yikai; Xie, Bin

2015-01-01

A novel rapid methodology for determining the chemical oxygen demand (COD) based on a thermal sensor with a flow injection analysis system was proposed and experimentally validated. The ability of this sensor to detect and monitor COD was based on the degree of enthalpy increase when sodium hypochlorite reacted with the organic content in water samples. The measurement results were correlated with COD and were compared against the conventional method using potassium dichromate. The assay required only 5–7 min rather than the 2 h required for evaluation by potassium dichromate. The linear range was 5–1000 mg/L COD, and the limit of detection was very low, 0.74 mg/L COD. Moreover, this method exhibited high tolerance to chloride ions; 0.015 mol/L chloride ions had no influence on the response. Finally, the sensor was used to detect the COD of different water samples; the results were verified by the standard dichromate method. PMID:26295397

Spectroscopic determination of thermal impulse in sub-second heating events using lanthanide-doped oxide precursors and phenomenological modeling

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

Anderson, Benjamin R., E-mail: branderson@wsu.edu; Gunawidjaja, Ray; Price, Patrick

2016-08-28

Using a mixture of crystalline-Ho:ZrO{sub 2}, precursor-Dy:Y{sub 2}O{sub 3}, and precursor-Eu:ZrO{sub 2} nanoparticles we develop thermal impulse sensors capable of measuring equivalent isothermal temperatures and durations during a heating event, with response times of <100 ms, and a temperature range of at least 673 K to 1173 K. In order to determine the temperature and duration from the sensors after the heating event we measure the sensors' fluorescence spectrum, which is then compared with lab based calibration data. By using two precursor materials with different reaction kinetics we are able to extract both temperature and duration. Based on blind sample testing we findmore » that the sensors and calculation method are accurate for measuring temperature and duration, but currently suffer a lack of precision due to difficulties in producing homogeneously heated samples.« less

STS-114 Engine Cut-off Sensor Anomaly Technical Consultation Report

NASA Technical Reports Server (NTRS)

Wilson, Timmy R.; Kichak, Robert A.; Ungar, Eugene K.; Cherney, Robert; Rickman, Steve L.

2009-01-01

The NESC consultation team participated in real-time troubleshooting of the Main Propulsion System (MPS) Engine Cutoff (ECO) sensor system failures during STS-114 launch countdown. The team assisted with External Tank (ET) thermal and ECO Point Sensor Box (PSB) circuit analyses, and made real-time inputs to the Space Shuttle Program (SSP) problem resolution teams. Several long-term recommendations resulted. One recommendation was to conduct cryogenic tests of the ECO sensors to validate, or disprove, the theory that variations in circuit impedance due to cryogenic effects on swaged connections within the sensor were the root cause of STS-114 failures.

Joint tests at INL and CEA of a transient hot wire needle probe for in-pile thermal conductivity measurement

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

Daw, J.E.; Knudson, D.L.; Villard, J.F.

2015-07-01

Thermal conductivity is a key property that must be known for proper design, testing, and deployment of new fuels and structural materials in nuclear reactors. Thermal conductivity is highly dependent on the physical structure, chemical composition, and the state of the material. Typically, thermal conductivity changes that occur during irradiation are currently measured out-of-pile using a 'cook and look' approach. But repeatedly removing samples from a test reactor to make measurements is expensive, has the potential to disturb phenomena of interest, and only provides understanding of the sample's end state when each measurement is made. There are also limited thermo-physicalmore » property data available for advanced fuels; and such data are needed for simulation codes, the development of next generation reactors, and advanced fuels for existing nuclear plants. Being able to quickly characterize fuel thermal conductivity during irradiation can improve the fidelity of data, reduce costs of post-irradiation examinations, increase understanding of how fuels behave under irradiation, and confirm or improve existing thermal conductivity measurement techniques. This paper discusses efforts to develop and evaluate an innovative in-pile thermal conductivity sensor based on the transient hot wire thermal conductivity method (THWM), using a single needle probe (NP) containing a line heat source and thermocouple embedded in the fuel. The sensor that has been designed and manufactured by the Idaho National Laboratory (INL) includes a unique combination of materials, geometry, and fabrication techniques that make the hot wire method suitable for in-pile applications. In particular, efforts were made to minimize the influence of the sensor and maximize fuel hot-wire heating. The probe has a thermocouple-like construction with high temperature resistant materials that remain ductile while resisting transmutation and materials interactions. THWM-NP prototypes were fabricated for both room temperature proof-of-concept evaluations and high temperature testing. Evaluations have been performed jointly by the INL and the French Alternative Energies and Atomic Energy Commission (CEA), both in Idaho Falls (USA) and in Cadarache (France), in the framework of a collaborative program for instrumentation of Material Testing Reactors. Initial tests were conducted on samples with a large range of thermal conductivities and temperatures ranging from 20 deg. C to 600 deg. C. Particularly, tests were recently performed on a sample having thermal conductivity and dimensions similar to UO{sub 2} and MOX nuclear fuels, in order to validate the ability of this sensor to operate for in-pile characterization of Light Water Reactors fuels. The results of the tests already completed at INL and CEA indicate that the Transient Hot Wire Needle Probe offers an enhanced method for in-pile detection of thermal conductivity. (authors)« less

Automatic Fault Recognition of Photovoltaic Modules Based on Statistical Analysis of Uav Thermography

NASA Astrophysics Data System (ADS)

Kim, D.; Youn, J.; Kim, C.

2017-08-01

As a malfunctioning PV (Photovoltaic) cell has a higher temperature than adjacent normal cells, we can detect it easily with a thermal infrared sensor. However, it will be a time-consuming way to inspect large-scale PV power plants by a hand-held thermal infrared sensor. This paper presents an algorithm for automatically detecting defective PV panels using images captured with a thermal imaging camera from an UAV (unmanned aerial vehicle). The proposed algorithm uses statistical analysis of thermal intensity (surface temperature) characteristics of each PV module to verify the mean intensity and standard deviation of each panel as parameters for fault diagnosis. One of the characteristics of thermal infrared imaging is that the larger the distance between sensor and target, the lower the measured temperature of the object. Consequently, a global detection rule using the mean intensity of all panels in the fault detection algorithm is not applicable. Therefore, a local detection rule based on the mean intensity and standard deviation range was developed to detect defective PV modules from individual array automatically. The performance of the proposed algorithm was tested on three sample images; this verified a detection accuracy of defective panels of 97 % or higher. In addition, as the proposed algorithm can adjust the range of threshold values for judging malfunction at the array level, the local detection rule is considered better suited for highly sensitive fault detection compared to a global detection rule.

Isotherm Sensor Calibration Program for Mars Science Laboratory Heat Shield Flight Data Analysis

NASA Technical Reports Server (NTRS)

Santos, Jose A.; Oishi, Tomo; Martinez, Ed R.

2011-01-01

Seven instrumented sensor plugs were installed on the Mars Science Laboratory heat shield in December 2008 as part of the Mars Science Laboratory Entry, Descent, and Landing Instrumentation (MEDLI) project. These sensor plugs contain four in-depth thermocouples and one Hollow aErothermal Ablation and Temperature (HEAT) sensor. The HEAT sensor follows the time progression of a 700 C isotherm through the thickness of a thermal protection system (TPS) material. The data can be used to infer char depth and, when analyzed in conjunction with the thermocouple data, the thermal gradient through the TPS material can also be determined. However, the uncertainty on the isotherm value is not well defined. To address this uncertainty, a team at NASA Ames Research Center is carrying out a HEAT sensor calibration test program. The scope of this test program is described, and initial results from experiments conducted in the laboratory to study the isotherm temperature of the HEAT sensor are presented. Data from the laboratory tests indicate an isotherm temperature of 720 C 60 C. An overview of near term arc jet testing is also given, including preliminary data from 30.48cm 30.48cm PICA panels instrumented with two MEDLI sensor plugs and tested in the NASA Ames Panel Test Facility. Forward work includes analysis of the arc jet test data, including an evaluation of the isotherm value based on the instant in time when it reaches a thermocouple depth.

Development of Light Powered Sensor Networks for Thermal Comfort Measurement

PubMed Central

Lee, Dasheng

2008-01-01

Recent technological advances in wireless communications have enabled easy installation of sensor networks with air conditioning equipment control applications. However, the sensor node power supply, through either power lines or battery power, still presents obstacles to the distribution of the sensing systems. In this study, a novel sensor network, powered by the artificial light, was constructed to achieve wireless power transfer and wireless data communications for thermal comfort measurements. The sensing node integrates an IC-based temperature sensor, a radiation thermometer, a relative humidity sensor, a micro machined flow sensor and a microprocessor for predicting mean vote (PMV) calculation. The 935 MHz band RF module was employed for the wireless data communication with a specific protocol based on a special energy beacon enabled mode capable of achieving zero power consumption during the inactive periods of the nodes. A 5W spotlight, with a dual axis tilt platform, can power the distributed nodes over a distance of up to 5 meters. A special algorithm, the maximum entropy method, was developed to estimate the sensing quantity of climate parameters if the communication module did not receive any response from the distributed nodes within a certain time limit. The light-powered sensor networks were able to gather indoor comfort-sensing index levels in good agreement with the comfort-sensing vote (CSV) preferred by a human being and the experimental results within the environment suggested that the sensing system could be used in air conditioning systems to implement a comfort-optimal control strategy. PMID:27873877

Development of a Wireless Network of Temperature Sensors for Yellowstone National Park (USA)

NASA Astrophysics Data System (ADS)

Munday, D. A.; Hutter, T.; Minolli, M.; Obraczka, K.; Manduchi, R.; Petersen, S.; Lowenstern, J. B.; Heasler, H.

2007-12-01

Temperature sensors deployed at Yellowstone clearly document that thermal features can vary in temperature on a variety of timescales and show regional correlations unrelated to meteorological variables such as air temperature. Yellowstone National Park (YNP) staff currently measures temperatures at over 40 thermal features and streams within the park, utilizing USGS stream gaging stations and portable data loggers deployed in geyser basins. The latter measure temperature every 1 to 15 minutes, and the data are physically downloaded after about 30 days. Installation of a wireless sensor network would: 1) save considerable time and effort in data retrieval, 2) minimize lost data due to equipment failure, and 3) provide a means to monitor thermal perturbations in near-real time. To meet this need, we developed a wireless sensor network capable of in-situ monitoring of air and water temperature. Temperature sensors are dispersed as nodes that communicate among themselves and through relays to a single base-station linked to the Internet. The small, weatherproof sensors operate unattended for over six months at temperatures as low as -40°C. Each uses an ultra-low-power Texas Instruments' MSP430 microcontroller and an SD card as mass storage. They are powered by 15Ah, 3.6 v, inert Li-ion batteries and transmit data via 900MHz radio modules with a 1-km range. The initial prototype consists of 4 nodes, and is designed to scale with additional nodes for finer spatial resolution and broader coverage. Temperature measurements are asynchronous from node to node, with intervals as frequent as 30 seconds. Data are stored internally to withstand temporary communication failures; underlying intelligent software is capable of re-routing data through alternative nodes to the base station and a MySQL data archiving system. We also developed a Google-Maps-based, front-end that displays the data, recent trends and sensor locations. The system was tested in the Santa Cruz Mountains and will be used at Yellowstone National Park during Fall 2007.

Experimental and numerical study on thermal conductivity of partially saturated unconsolidated sands

NASA Astrophysics Data System (ADS)

Lee, Youngmin; Keehm, Youngseuk; Kim, Seong-Kyun; Shin, Sang Ho

2016-04-01

A class of problems in heat flow applications requires an understanding of how water saturation affects thermal conductivity in the shallow subsurface. We conducted a series of experiments using a sand box to evaluate thermal conductivity (TC) of partially saturated unconsolidated sands under varying water saturation (Sw). We first saturated sands fully with water and varied water saturation by drainage through the bottom of the sand box. Five water-content sensors were integrated vertically into the sand box to monitor water saturation changes and a needle probe was embedded to measure thermal conductivity of partially saturated sands. The experimental result showed that thermal conductivity decreases from 2.5 W/mK for fully saturated sands to 0.7 W/mK when water saturation is 5%. We found that the decreasing trend is quite non-linear: highly sensitive at very high and low water saturations. However, the boundary effects on the top and the bottom of the sand box seemed to be responsible for this high nonlinearity. We also found that the determination of water saturation is quite important: the saturation by averaging values from all five sensors and that from the sensor at the center position, showed quite different trends in the TC-Sw domain. In parallel, we conducted a pore-scale numerical modeling, which consists of the steady-state two-phase Lattice-Boltzmann simulator and FEM thermal conduction simulator on digital pore geometry of sand aggregation. The simulation results showed a monotonous decreasing trend, and are reasonably well matched with experimental data when using average water saturations. We concluded that thermal conductivity would decrease smoothly as water saturation decreases if we can exclude boundary effects. However, in dynamic conditions, i.e. imbibition or drainage, the thermal conductivity might show hysteresis, which can be investigated with pore-scale numerical modeling with unsteady-state two-phase flow simulators in our future work.

Applications of HCMM data to soil moisture snow and estuarine current studies. [Cooper River and Delaware Bay

NASA Technical Reports Server (NTRS)

Wiesnet, D. R. (Principal Investigator); Mcginnis, D. F.; Matson, M.

1980-01-01

The author has identified the following significant results. The HCMM thermal data are useful for monitoring estuarine surface thermal patterns. Estuarine thermal patterns, are, under certain conditions, indicative of the surface tidal current circulation patterns. Under optimum conditions, estuaries as small as the Cooper River (i.e., approximately 100 sq km) can be monitored for tidal/thermal circulation patterns by HCMM-type IR sensors.

Characterization Techniques for a MEMS Electric-Field Sensor in Vacuum

DTIC Science & Technology

2012-01-01

nected so that the noise contributions of the transimpedance amplifier and the digitizer may be determined. The raw voltage data, after processing...of Vrms/rtHz. The noise may be seen in terms of the device trans- duction physics, signal conditioning ( transimpedance amp), and DAQ. (right) Field...Sensor using Thermal Actua- tors with Mechanically Amplified Response,” Solid-State Sensors, Actuators and Microsystems Confer- ence, 2007. TRANSDUCERS

Modeling FBG sensors sensitivity from cryogenic temperatures to room temperature as a function of metal coating thickness

NASA Astrophysics Data System (ADS)

Vendittozzi, Cristian; Felli, Ferdinando; Lupi, Carla

2018-05-01

Fiber optics with photo-imprinted Bragg grating have been studied in order to be used as temperature sensors in cryogenic applications. The main disadvantage presented by Fiber Bragg Grating (FBG) sensors is the significant drop in sensitivity as temperature decreases, mainly due to the critical lowering of the thermo-optic coefficient of the fiber and the very low thermal expansion coefficient (CTE) of fused silica at cryogenic temperatures. Thus, especially for the latter, it is important to enhance sensitivity to temperature by depositing a metal coating presenting higher CTE. In this work the thermal sensitivity of metal-coated FBG sensors has been evaluated by considering their elongation within temperature variations in the cryogenic range, as compared to bare fiber sensors. To this purpose, a theoretical model simulating elongation of metal-coated sensors has been developed. The model has been used to evaluate the behaviour of different metals which can be used as coating (Ni, Cu, Al, Zn, Pb and In). The optimal coating thickness has been calculated at different fixed temperature (from 5 K to 100 K) for each metal. It has been found that the metal coating effectiveness depends on thickness and operating temperature in accordance to our previous experimental work and theory suggest.

Dynamics, Control, and Fabrication of Micro Embedded Heaters and Sensors for Micro SMA Active Endoscopes

NASA Astrophysics Data System (ADS)

Aphanuphong, Sutha

This research investigates design and control of an active catheter for minimally invasive medical procedures. Microfabrication techniques are developed and several prototypes were constructed. The understanding and analysis results from each design iteration are utilized to improve the overall design and the performance of each revision. An innovative co-fabrication method is explored to simplify the fabrication process and also improve the quality, repeatability, and reliability of the active catheter. This co-fabrication method enables a unique compact integrated heater and sensor film to be directly constructed on a shape memory alloy (SMA) sheet and to be utilized as an outline mask to pattern a micro SMA actuator. There are two functions integrated in the sensor film: heat sources to actuate the micro SMA actuator and sensors to provide temperature and strain of the active catheter to closed-loop control algorithms. Three main aspects are explored in this dissertation: thermal dynamics in the MicroFlex (muF) film and its effect on the sensor capabilities; non-minimum phase behavior and its effect on control performance, and film micro fabrication design and its effect on thermal dynamics. The sensor film developed from this understanding is able to deliver excellent heating and sensing performance with a simple design.

Cryogenic thermometry for refrigerant distribution system of JT-60SA

NASA Astrophysics Data System (ADS)

Natsume, K.; Murakami, H.; Kizu, K.; Yoshida, K.; Koide, Y.

2015-12-01

JT-60SA is a fully superconducting fusion experimental device involving Japan and Europe. The cryogenic system supplies supercritical or gaseous helium to superconducting coils through valve boxes or coil terminal boxes and in-cryostat pipes. There are 86 temperature measurement points at 4 K along the distribution line. Resistance temperature sensors will be installed on cooling pipes in vacuum. In this work, two sensor attachment methods, two types of sensor, two thermal anchoring methods, and two sensor fixation materials have been experimentally evaluated in terms of accuracy and mass productivity. Finally, the verification test of thermometry has been conducted using the sample pipe fabricated in the same way to the production version, which has been decided by the comparison experiments. The TVO sensor is attached by the saddle method with Apiezon N grease and the measurement wires made of phosphor bronze are wound on the pipe with Stycast 2850FT as the thermal anchoring. A Cernox sensor is directly immersed in liquid helium as a reference thermometer during the experiment. The measured temperature difference between the attached one and reference one has been within ±15 mK in the range of 3.40-4.73 K. It has satisfies the accuracy requirement of 0.1 K.

Gas Sensors Based on One Dimensional Nanostructured Metal-Oxides: A Review

PubMed Central

Arafat, M. M.; Dinan, B.; Akbar, Sheikh A.; Haseeb, A. S. M. A.

2012-01-01

Recently one dimensional (1-D) nanostructured metal-oxides have attracted much attention because of their potential applications in gas sensors. 1-D nanostructured metal-oxides provide high surface to volume ratio, while maintaining good chemical and thermal stabilities with minimal power consumption and low weight. In recent years, various processing routes have been developed for the synthesis of 1-D nanostructured metal-oxides such as hydrothermal, ultrasonic irradiation, electrospinning, anodization, sol-gel, molten-salt, carbothermal reduction, solid-state chemical reaction, thermal evaporation, vapor-phase transport, aerosol, RF sputtering, molecular beam epitaxy, chemical vapor deposition, gas-phase assisted nanocarving, UV lithography and dry plasma etching. A variety of sensor fabrication processing routes have also been developed. Depending on the materials, morphology and fabrication process the performance of the sensor towards a specific gas shows a varying degree of success. This article reviews and evaluates the performance of 1-D nanostructured metal-oxide gas sensors based on ZnO, SnO2, TiO2, In2O3, WOx, AgVO3, CdO, MoO3, CuO, TeO2 and Fe2O3. Advantages and disadvantages of each sensor are summarized, along with the associated sensing mechanism. Finally, the article concludes with some future directions of research. PMID:22969344

The MEDA's Radiometer TIRS for the MARS2020 Mission

NASA Astrophysics Data System (ADS)

Pérez Izquierdo, Joel; Sebastián Martínez, Eduardo; Bravo, Andrés; Ferrándiz, Ricardo; Ramos, Miguel; Martínez, Germán; Rodríguez Manfredi, Jose Antonio

2016-10-01

The TIRS (Thermal InfraRed Sensor) instrument is one of the payloads of NASA MARS2020 mission, that is expected to take off in 2020, and is designed to operate for at least three Martian years on surface. The TIRS is part of the Mars Environmental Dynamics Analyzer (MEDA), formed for other environmental sensors, which will be placed in the MARS2020 Rover, and is been developing by the Spanish Center of Astrobiology (CAB).The main objectives of MEDA's Thermal InfraRed Sensor are:-Characterize the net radiative forcing (within 10%), and constrain the conductive forcing at the local surface and near-surface atmosphere.-Record the surface skin temperature and the UV-VIS-NIR irradiance solar flux at an accuracy of [10%] at full range of the atmosphere.TIRS design has heritage from GTS-REMS on the Mars Science Laboratory, in the Curiosity Rover. The aim of the instrument is to measure the radiative flux emitted from the Martian surface, sky and the CO2 atmosphere using five thermopiles sensors in four wavelength bands, model TS100 provided by IPHT (Institute of Photonic Technology, Jena, Germany). The TIRS has three downward pointing thermopiles to measure the IR fluxes emitted by the surface, separating brightness surface temperature from emissivity and surface reflected upward short wave radiation, using the thermopiles IR3 (0.3-3 µm), IR4 (6.5-inf µm), IR5 (8-14 µm). Additionally, it has two more thermopiles pointing to the sky, the thermopiles IR1 (6.5-inf µm) and IR2 (14.5-15.5 µm), which captures the downward fluxes of thermal infrared radiation and air temperature nearby the sensor.Thermopiles are accommodated inside a mechanical assembly that is designed to ensure a low thermal gradient. This assembly also accommodates a calibration plate, aimed to intercept part of the thermopiles FOV, and capable to do an in-flight recalibration.

Impedance microflow cytometry for viability studies of microorganisms

NASA Astrophysics Data System (ADS)

Di Berardino, Marco; Hebeisen, Monika; Hessler, Thomas; Ziswiler, Adrian; Largiadèr, Stephanie; Schade, Grit

2011-02-01

Impedance-based Coulter counters and its derivatives are widely used cell analysis tools in many laboratories and use normally DC or low frequency AC to perform these electrical analyses. The emergence of micro-fabrication technologies in the last decade, however, provides a new means of measuring electrical properties of cells. Microfluidic approaches combined with impedance spectroscopy measurements in the radio frequency (RF) range increase sensitivity and information content and thus push single cell analyses beyond simple cell counting and sizing applications towards multiparametric cell characterization. Promising results have been shown already in the fields of cell differentiation and blood analysis. Here we emphasize the potential of this technology by presenting new data obtained from viability studies on microorganisms. Impedance measurements of several yeast and bacteria strains performed at frequencies around 10 MHz enable an easy discrimination between dead and viable cells. Moreover, cytotoxic effects of antibiotics and other reagents, as well as cell starvation can also be monitored easily. Control analyses performed with conventional flow cytometers using various fluorescent dyes (propidium iodide, oxonol) indicate a good correlation and further highlight the capability of this device. The label-free approach makes on the one hand the use of usually expensive fluorochromes obsolete, on the other hand practically eliminates laborious sample preparation procedures. Until now, online cell monitoring was limited to the determination of viable biomass, which provides rather poor information of a cell culture. Impedance microflow cytometry, besides other aspects, proposes a simple solution to these limitations and might become an important tool for bioprocess monitoring applications in the biotech industry.

Modeling studies for a Mars penetrator heat flow measurement

NASA Technical Reports Server (NTRS)

Keihm, S. J.; Langseth, M. G.

1976-01-01

There were, two different design concepts considered for the purpose of measuring heat flow as part of a Mars penetrator mission. The first of the tentative designs utilizes temperature sensors emplaced along the trailing umbilicus at regularly spaced intervals, no greater than 1m, which is thermally coupled to the adjacent regolith radiatively and possibly convectively or conductively. The second of the heat flow designs considered requires the radial deployment of two or more low thermal mass temperature sensors outward from the penetrator body over a vertical (depth) range on the order of 1m.

Sensor fusion and augmented reality with the SAFIRE system

NASA Astrophysics Data System (ADS)

Saponaro, Philip; Treible, Wayne; Phelan, Brian; Sherbondy, Kelly; Kambhamettu, Chandra

2018-04-01

The Spectrally Agile Frequency-Incrementing Reconfigurable (SAFIRE) mobile radar system was developed and exercised at an arid U.S. test site. The system can detect hidden target using radar, a global positioning system (GPS), dual stereo color cameras, and dual stereo thermal cameras. An Augmented Reality (AR) software interface allows the user to see a single fused video stream containing the SAR, color, and thermal imagery. The stereo sensors allow the AR system to display both fused 2D imagery and 3D metric reconstructions, where the user can "fly" around the 3D model and switch between the modalities.

Improvements of Real Time First Motion Focal Mechanism and Noise Characteristics of New Sites at the Puerto Rico Seismic Network

NASA Astrophysics Data System (ADS)

Williams, D. M.; Lopez, A. M.; Huerfano, V.; Lugo, J.; Cancel, J.

2011-12-01

Seismic networks need quick and efficient ways to obtain information related to seismic events for the purposes of seismic activity monitoring, risk assessment, and scientific knowledge among others. As part of an IRIS summer internship program, two projects were performed to provide a tool for quick faulting mechanism and improve seismic data at the Puerto Rico Seismic Network (PRSN). First, a simple routine to obtain a focal mechanisms, the geometry of the fault, based on first motions was developed and implemented for data analysts routine operations at PRSN. The new tool provides the analyst a quick way to assess the probable faulting mechanism that occurred while performing the interactive earthquake location procedure. The focal mechanism is generated on-the-fly when data analysts pick P wave arrivals onsets and motions. Once first motions have been identified, an in-house PRSN utility is employed to obtain the double couple representation and later plotted using GMT's psmeca utility. Second, we addressed the issue of seismic noise related to thermal fluctuations inside seismic vaults. Seismic sites can be extremely noisy due to proximity to cultural activities and unattended thermal fluctuations inside sensor housings, thus resulting in skewed readings. In the past, seismologists have used different insulation techniques to reduce the amount of unwanted noise that a seismometers experience due to these thermal changes with items such as Styrofoam, and fiber glass among others. PRSN traditionally uses Styrofoam boxes to cover their seismic sensors, however, a proper procedure to test how these method compare to other new techniques has never been approached. The deficiency of properly testing these techniques in the Caribbean and especially Puerto Rico is that these thermal fluctuations still happen because of the intense sun and humidity. We conducted a test based on the methods employed by the IRIS Transportable Array, based on insulation by sand burial of the sensor. Two Guralps CMG-3T's connected to RefTek's 150 digitizers were used at PRSN's MPR site seismic vault to compare the two types of insulation. Two temperature loggers were placed along each seismic sensor for a period of one week to observe how much thermal fluctuations occur in each insulation method and then compared its capability for noise reduction due to thermal fluctuations. With only a single degree Celsius fluctuation inside the sand (compared to almost twice that value for the foam) the sensor buried in sand provided the best insulation for the seismic vault. In addition, the quality of the data was analyzed by comparing both sensors using PQLX. We show results of this analysis and also provide a site characteristic of new stations to be included in the daily earthquake location operations at the PRSN.

Testing and Evaluation of Low-Light Sensors to Enhance Intelligence, Surveillance, and Reconnaissance (ISR) and Real-Time Situational Awareness

DTIC Science & Technology

2009-03-01

infrared, thermal , or night vision applications. Understanding the true capabilities and limitations of the ALAN camera and its applicability to a...an option to more expensive infrared, thermal , or night vision applications. Ultimately, it will be clear whether the configuration of the Kestrel...45  A.  THERMAL CAMERAS................................................................................45  1

Permanent-Change Thermal Paints for Hypersonic Flight-Test

DTIC Science & Technology

2010-09-24

thermochromic liquid crystals (Ireland et al. 1999, Ireland & Jones 2000), and temperature sensitive paints (Liu & Sullivan 2005), thermal paints are...surfaces and fin-fuselage junctions, shock boundary layer interactions, scramjet combustion chambers and around control thrusters. Thermal paints can...use of discrete wired sensors may also not practical on some locations on a hypersonic vehicle. Thermochromic liquid crystals Coatings of

Design, Fabrication, Characterization and Modeling of Integrated Functional Materials

DTIC Science & Technology

2013-10-01

coated microwire to change the temperature of an FBG. We show below that the proposed sensor probe, with a relatively poor thermal coupling with FBG...Seebeck coefficient and decreased thermal conductivity due to the phenomenological properties of nanometer length scales, including enhanced...nanocomposites as compared to bulk polycrystalline materials, in addition to similar thermal conductivities , results in enhanced room temperature ZT as

Linearly chirped fiber Bragg grating response to thermal gradient: from bench tests to the real-time assessment during in vivo laser ablations of biological tissue.

PubMed

Saccomandi, Paola; Varalda, Ambra; Gassino, Riccardo; Tosi, Daniele; Massaroni, Carlo; Caponero, Michele A; Pop, Raoul; Korganbayev, Sanzhar; Perrone, Guido; Diana, Michele; Vallan, Alberto; Costamagna, Guido; Marescaux, Jacques; Schena, Emiliano

2017-09-01

The response of a fiber optic sensor [linearly chirped fiber Bragg grating (LCFBG)] to a linear thermal gradient applied on its sensing length (i.e., 1.5 cm) has been investigated. After these bench tests, we assessed their feasibility for temperature monitoring during thermal tumor treatment. In particular, we performed experiments during ex vivo laser ablation (LA) in pig liver and in vivo thermal ablation in animal models (pigs). We investigated the following: (i) the relationship between the full width at half maximum of the LCFBG spectrum and the temperature difference among the extremities of the LCFBG and (ii) the relationship between the mean spectrum wavelength and the mean temperature acting on the LCFBG sensing area. These relationships showed a linear trend during both bench tests and LA in animal models. Thermal sensitivity was significant although different values were found with regards to bench tests and animal experiments. The linear trend and significant sensitivity allow hypothesizing a future use of this kind of sensor to monitor both temperature gradient and mean temperature within a tissue undergoing thermal treatment. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Caldera unrest detected with seawater temperature anomalies at Deception Island, Antarctic Peninsula

NASA Astrophysics Data System (ADS)

Berrocoso, M.; Prates, G.; Fernández-Ros, A.; Peci, L. M.; de Gil, A.; Rosado, B.; Páez, R.; Jigena, B.

2018-04-01

Increased thermal activity was detected to coincide with the onset of volcano inflation in the seawater-filled caldera at Deception Island. This thermal activity was manifested in pulses of high water temperature that coincided with ocean tide cycles. The seawater temperature anomalies were detected by a thermometric sensor attached to the tide gauge (bottom pressure sensor). This was installed where the seawater circulation and the locations of known thermal anomalies, fumaroles and thermal springs, together favor the detection of water warmed within the caldera. Detection of the increased thermal activity was also possible because sea ice, which covers the entire caldera during the austral winter months, insulates the water and thus reduces temperature exchange between seawater and atmosphere. In these conditions, the water temperature data has been shown to provide significant information about Deception volcano activity. The detected seawater temperature increase, also observed in soil temperature readings, suggests rapid and near-simultaneous increase in geothermal activity with onset of caldera inflation and an increased number of seismic events observed in the following austral summer.

Monitoring volcanic thermal activity by Robust Satellite Techniques: achievements and perspectives

NASA Astrophysics Data System (ADS)

Tramutoli, V.; Marchese, F.; Mazzeo, G.; Pergola, N.

2009-12-01

Satellite data have been increasingly used in last decades to study active volcanoes and to monitor thermal activity variation in space-time domain. Several satellite techniques and original methods have been developed and tested, devoted to hotspot detection and thermal monitoring. Among them, a multi-temporal approach, named RST (Robust Satellite Techniques), has shown high performances in detecting hotspots, with a low false positive rate under different observational and atmospheric conditions, providing also a potential toward low-level thermal anomalies which may announce incoming eruptions. As the RST scheme is intrinsically exportable on different geographic areas and satellite sensors, it has been applied and tested on a number of volcanoes and in different environmental conditions. This work presents major results and outcomes of studies carried out on Etna and Stromboli (Italy), Merapi (Java Indonesia), Asamayama (Japan), Jebel Al Tair (Yemen) by using different satellite systems and sensors (e.g. NOAA-AVHRR, EOS-MODIS, MSG-SEVIRI). Performances on hotspot detection, early warning and real-time monitoring, together with capabilities in possible thermal precursor identification, will be presented and discussed.

Spice In Martian Soil

NASA Astrophysics Data System (ADS)

Seiferlin, K.; Spohn, T.; Spice Team

The Netlander mission offers a unique opportunity to study the surface and the inte- rior of Mars at four different locations at the same time. In addition to real "network"- science, where the presence of four stations is a 'must' to address global science as- pects, local, landing site-related instruments can more than double our knowledge of the surface of Mars, compared to the three landing sites (Viking 1 and 2, Pathfinder) we are currently familiar with. The SPICE instrument will characterize the soil at the landing sites. Force sensors integrated into the seismometer legs (three per station) will determine the mechanical strength of the soil. Thermal sensors will measure the local soil temperature, the thermal inertia and the thermal diffusivity independently, thus allowing us to determine the thermal conductivity and the volumetric heat capac- ity of the soil. These properties will tell us about (1) soil cementation ("duricrust"), (2) volatile exchange with the atmosphere, (3) grain size, (4) near-surface stratigra- phy, and (5) will finally provide ground truth for remote sensing data such as that from Mars Global Surveyor's thermal emission spectrometer.

Relationship between pressure and reaction violence in thermal explosions

NASA Astrophysics Data System (ADS)

Smilowitz, L.; Henson, B. F.; Rodriguez, G.; Remelius, D.; Baca, E.; Oschwald, D.; Suvorova, N.

2017-01-01

Reaction violence of a thermal explosion is determined by the energy release rate of the explosive and the coupling of that energy to the case and surroundings. For the HMX and TATB based secondary high explosives studied, we have observed that temperature controls the time to explosion and pressure controls the final energy release rate subsequent to ignition. Pressure measurements in the thermal explosion regime have been notoriously difficult to make due to the extreme rise in temperature which is also occurring during a thermal explosion. We have utilized several different pressure measurement techniques for several different secondary high explosives. These techniques include commercially available piezoelectric and piezoresistive sensors which we have utilized in the low pressure (sub 30 MPa) range of PBX 9502 thermal explosions, and fiber Bragg grating sensors for the higher pressure range (up to GPa) for PBX9501 experiments. In this talk, we will compare the measurement techniques and discuss the pressures measured for the different formulations studied. Simultaneous x-ray radiography measurements of burn velocity will also be shown and correlations between pressure, burn velocity, and reaction violence will be discussed.

DESIGN NOTE: Microcontroller-based multi-sensor apparatus for temperature control and thermal conductivity measurement

NASA Astrophysics Data System (ADS)

Mukaro, R.; Gasseller, M.; Kufazvinei, C.; Olumekor, L.; Taele, B. M.

2003-08-01

A microcontroller-based multi-sensor temperature measurement and control system that uses a steady-state one-dimensional heat-flow technique for absolute determination of thermal conductivity of a rigid poor conductor using the guarded hot-plate method is described. The objective of this project was to utilize the latest powerful, yet inexpensive, technological developments, sensors, data acquisition and control system, computer and application software, for research and teaching by example. The system uses an ST6220 microcontroller and LM335 temperature sensors for temperature measurement and control. The instrument interfaces to a computer via the serial port using a Turbo C++ programme. LM335Z silicon semiconductor temperature sensors located at different axial locations in the heat source were calibrated and used to measure temperature in the range from room temperature (about 293 K) to 373 K. A zero and span circuit was used in conjunction with an eight-to-one-line data multiplexer to scale the LM335 output signals to fit the 0 5.0 V full-scale input of the microcontroller's on-chip ADC and to sequentially measure temperature at the different locations. Temperature control is achieved by using software-generated pulse-width-modulated signals that control power to the heater. This article emphasizes the apparatus's instrumentation, the computerized data acquisition design, operation and demonstration of the system as a purposeful measurement system that could be easily adopted for use in the undergraduate laboratory. Measurements on a 10 mm thick sample of polyurethane foam at different temperature gradients gave a thermal conductivity of 0.026 +/- 0.004 W m-1 K-1.

Fabrication and Characterization of Miniaturized Thermocouples

NASA Astrophysics Data System (ADS)

Munzel, Marco; Peinke, Joachim; Kittel, Achim

2002-11-01

The measurement of thermal fluctuations is important for discovering transport features of a passive scalar in fluids. We present a thermal sensor based on a miniaturized thermocouple. Its coaxial setup results from the fabrication as a micropipette normally used in neurobiology. The glass micropipettes contain a core of gold, antimony, or resistance wire and are coated with platinum. The core material is inserted as molten metal or wire and thinned during the fabrication process. The achieved tip diameters are 1μm and less which enhance the spatial and temporal resolution significantly. Because of its chemically inert coating, these sensors are applicative for detecting temperature fluctuations in large variety of liquids and gases. In addition, such thermocouples are intrinsically suitable for applications in scanning probe microscopy. The characterization of these sensors and first results from turbulent free-jet measurements are presented.

Innovativ Airborne Sensors for Disaster Management

NASA Astrophysics Data System (ADS)

Altan, M. O.; Kemper, G.

2016-06-01

Modern Disaster Management Systems are based on 3 columns, crisis preparedness, early warning and the final crisis management. In all parts, special data are needed in order to analyze existing structures, assist in the early warning system and in the updating after a disaster happens to assist the crises management organizations. How can new and innovative sensors assist in these tasks? Aerial images have been frequently used in the past for generating spatial data, however in urban structures not all information can be extracted easily. Modern Oblique camera systems already assist in the evaluation of building structures to define rescue paths, analyze building structures and give also information of the stability of the urban fabric. For this application there is no need of a high geometric accurate sensor, also SLC Camera based Oblique Camera system as the OI X5, which uses Nikon Cameras, do a proper job. Such a camera also delivers worth full information after a Disaster happens to validate the degree of deformation in order to estimate stability and usability for the population. Thermal data in combination with RGB give further information of the building structure, damages and potential water intrusion. Under development is an oblique thermal sensor with 9 heads which enables nadir and oblique thermal data acquisition. Beside the application for searching people, thermal anomalies can be created out of humidity in constructions (transpiration effects), damaged power lines, burning gas tubes and many other dangerous facts. A big task is in the data analysis which should be made automatically and fast. This requires a good initial orientation and a proper relative adjustment of the single sensors. Like that, many modern software tools enable a rapid data extraction. Automated analysis of the data before and after a disaster can highlight areas of significant changes. Detecting anomalies are the way to get the focus on the prior area. Also Lidar supports Disaster management by analyzing changes in the DSM before and after the "event". Advantage of Lidar is that beside rain and clouds, no other weather conditions limit their use. As an active sensor, missions in the nighttime are possible. The new mid-format cameras that make use CMOS sensors (e.g. Phase One IXU1000) can capture data also under poor and difficult light conditions and might will be the first choice for remotely sensed data acquisition in aircrafts and UAVs. UAVs will surely be more and more part of the disaster management on the detailed level. Today equipped with video live cams using RGB and Thermal IR, they assist in looking inside buildings and behind. Thus, they can continue with the aerial survey where airborne anomalies have been detected.

Mars2020 Entry, Descent, and Landing Instrumentation 2 (MEDLI2) Do No Harm Test Series

NASA Technical Reports Server (NTRS)

Swanson, Gregory; Santos, Jose; White, Todd; Bruce, Walt; Kuhl, Chris; Wright, Henry

2017-01-01

A total of seventeen instrumented thermal sensor plugs, eight pressure transducers, two heat flux sensors, and one radiometer are planned to be utilized on the Mars 2020 missions thermal protection system (TPS) as part of the Mars Entry, Descent, and Landing Instrumentation II (MEDLI2) project. Of the MEDLI2 instrumentation, eleven instrumented thermal plugs and seven pressure transducers will be installed on the heatshield of the Mars 2020 vehicle while the rest will be installed on the backshell. The goal of the MEDLI2 instrumentation is to directly inform the large performance uncertainties that contribute to the design and validation of a Mars entry system. A better understanding of the entry environment and TPS performance could lead to reduced design margins enabling a greater payload mass-fraction and smaller landing ellipses. To prove that the MEDLI2 system will not degrade the performance of the Mars 2020 TPS, an Aerothermal Do No Harm (DNH) test series was designed and conducted. Like Mars 2020s predecessor, Mars Science Laboratory (MSL), the heatshield material will be Phenolic Impregnated Carbon Ablator (PICA); the Mars 2020 entry conditions are enveloped by the MSL design environments, therefore the development and qualification testing performed during MEDLI is sufficient to show that the similar MEDLI2 heatshield instrumentation will not degrade PICA performance. However, given that MEDLI did not include any backshell instrumentation, the MEDLI2 team was required to design and execute a DNH test series utilizing the backshell TPS material (SLA-561V) with the intended flight sensor suite. To meet the requirements handed down from Mars 2020, the MEDLI2 DNH test series emphasized the interaction between the MEDLI2 sensors and sensing locations with the surrounding backshell TPS and substrucutre. These interactions were characterized by performing environmental testing of four 12 by 12 test panels, which mimicked the construction of the backshell TPS and the integration of the MEDLI2 sensors as seen in Figure 1. The testing included thermal vacuumcycling, random vibration, shock, and arc jet testing. The test panels were fabricated by Lockheed Martin, establishing techniques that will be utilized during the Mars 2020 vehicle installation. Each test panel included one thermal sensor plug (two embedded thermocouples), one heat flux sensor, and multiple pressure port holes for evaluation.This presentation will discuss the planning and execution of the MEDLI2 DNH test series. Selected highlights and results of each environmental test will be presented, and lessons learned will be addressed that will feed forward into the planning for the MEDLI2 flight system certification testing.

MUPUS --- a Suite of Small Instruments for the ROSETTA Surface Science Package to Measure the Thermal and Mechanical Properties of a Comet Nucleus

NASA Astrophysics Data System (ADS)

Spohn, T.; MUPUS Team

1996-09-01

The Surface Science Package, which will be deployed in course of the ROSETTA mission on the surface of the target comet, offers the unprecedented opportunity to study the physical properties and dominating processes of a comet nucleus in situ. While most SSP experiments focuse on composition and chemistry, the MUPUS instrument package is aimed to study the energy balance of the nucleus/coma interface and the evolution of key thermal and mechanical parameters. Unlike planetary evolution, cometary evolution is influenced by the energy input at the surface. The near surface layers are accessible with some effort and may thus be directly studied. A penetrator equipped with temperature sensors and heaters (MUPUS--PEN) aims to measure the vertical temperature distribution (PEN--TP) and the thermal conductivity (PEN--THC) in the first tens of centimeters of the nucleus as they evolve with time. A combined evaluation of the PEN--TP and PEN--THC data will allow to understand vertical surface heat flow into or from the comet nucleus and the energy balance of the comet. The surface temperature will be measured with an infrared thermal mapper (MUPUS TM). Both thermal sensors will provide a ground truth for IR data from the orbiter. The PEN--M sensor will measure mechanical properties like hardness and grain size during penetration. A compton backscatter densitometer (CBD) will be used to measure the density. Additional temperature sensors and penetrometers in the SSP's anchor(s) will supplement the data and expand the volume probed. The results will help to understand the onset of activity, gas and dust emission, which will be measured by the orbiter. Understanding the dominating processes and their time scales allows to determine the present state of the surface material ("Is the matter found close to the surface pristine?") as well as extrapolation both into the past and the future.

Thermal Infrared Sensor (TIRS) Instrument Thermal Subsystem Design and Lessons Learned

NASA Technical Reports Server (NTRS)

Otero, Veronica; Mosier, Carol; Neuberger, David

2013-01-01

The Thermal Infrared Sensor (TIRS) is one of two instruments on the Landsat Data Continuity Mission (LDCM), which is scheduled to launch in February of 2013. The TIRS instrument was officially added to the mission later in the flow, which led to a highly aggressive schedule that became one of the main drivers during instrument development. The thermal subsystem design of the TIRS Sensor Unit is comprised of five thermal zones which range in temperature from less than 43 Kelvin to 330 Kelvin. Most zones are proportional heater controlled, and all are within a volume of 35 cu.ft. A two-stage cryocooler is used to cool the "cold stage" including three QWIP detectors to less than 43 Kelvin, and cool the "warm stage" to 105 Kelvin. The excess power dissipation from the cryocooler is rejected via ammonia transport heat pipes to a dedicated Cryocooler Radiator with embedded ammonia heat pipes. The cryogenic subsystem includes a series of shells used to radiatively and conductively isolate the cold stage from the warmer surroundings. The Optical System (telescope) is passively cooled to 180-190 Kelvin using a "thermal link" (comprised of a Flexible Conductive Thermal Strap and an APG Bar) which couples the telescope stage to a dedicated radiator with embedded ethane heat pipes. The Scene Select Mechanism, which is responsible for moving the Scene Select Mirror to three distinct positions (including Nadir, Space, and On-board Black Body Calibrator pointing), runs nominally at 278 Kelvin and is thermally isolated from the cryogenic thermal zones. The On-board Black Body Calibrator requires a dedicated radiator which allows for a temperature range of 260-330 Kelvin at the Source. The detectors are powered by the FPE Box, which is mounted to the nadir external surface of the composite honeycomb structure. There are two additional electronics boxes which are wet-mounted directly to the spacecraft shear panel, the Main Electronics Box and Cryocooler Electronics Box; thermal control of these boxes is the responsibility of Orbital Sciences Corporation, the spacecraft developer. The TIRS thermal subsystem design was successfully verified during months of testing campaign, from component & subsystem level to two instrument-level thermal vacuum tests. The Instrument, despite an aggressive schedule, was delivered to the spacecraft vendor in February of 2012 and is currently undergoing the final stages of spacecraft environmental testing in preparation for launch.

Thermally assisted sensor for conformity assessment of biodiesel production

NASA Astrophysics Data System (ADS)

Kawano, M. S.; Kamikawachi, R. C.; Fabris, J. L.; Muller, M.

2015-02-01

Although biodiesel can be intentionally tampered with, impairing its quality, ineffective production processes may also result in a nonconforming final fuel. For an incomplete transesterification reaction, traces of alcohol (ethanol or methanol) or remaining raw material (vegetable oil or animal fats) may be harmful to consumers, the environment or to engines. Traditional methods for biodiesel assessment are complex, time consuming and expensive, leading to the need for the development of new and more versatile processes for quality control. This work describes a refractometric fibre optic based sensor that is thermally assisted, developed to quantify the remaining methanol or vegetable oil in biodiesel blends. The sensing relies on a long period grating to configure an in-fibre interferometer. A complete analytical routine is demonstrated for the sensor allowing the evaluation of the biodiesel blends without segregation of the components. The results show the sensor can determine the presence of oil or methanol in biodiesel with a concentration ranging from 0% to 10% v/v. The sensor presented a resolution and standard combined uncertainty of 0.013% v/v and 0.62% v/v for biodiesel-oil samples, and 0.007% v/v and 0.22% v/v for biodiesel-methanol samples, respectively.

Self-correcting electronically scanned pressure sensor

NASA Technical Reports Server (NTRS)

Gross, C. (Inventor)

1983-01-01

A multiple channel high data rate pressure sensing device is disclosed for use in wind tunnels, spacecraft, airborne, process control, automotive, etc., pressure measurements. Data rates in excess of 100,000 measurements per second are offered with inaccuracies from temperature shifts less than 0.25% (nominal) of full scale over a temperature span of 55 C. The device consists of thirty-two solid state sensors, signal multiplexing electronics to electronically address each sensor, and digital electronic circuitry to automatically correct the inherent thermal shift errors of the pressure sensors and their associated electronics.

Highly Sensitive Thin-Film Field-Effect Transistor Sensor for Ammonia with the DPP-Bithiophene Conjugated Polymer Entailing Thermally Cleavable tert-Butoxy Groups in the Side Chains.

PubMed

Yang, Yang; Zhang, Guanxin; Luo, Hewei; Yao, Jingjing; Liu, Zitong; Zhang, Deqing

2016-02-17

The sensing and detection of ammonia have received increasing attention in recent years because of the growing emphasis on environmental and health issues. In this paper, we report a thin-film field-effect transistor (FET)-based sensor for ammonia and other amines with remarkable high sensitivity and satisfactory selectivity by employing the DPP-bithiophene conjugated polymer pDPPBu-BT in which tert-butoxycarboxyl groups are incorporated in the side chains. This polymer thin film shows p-type semiconducting property. On the basis of TGA and FT-IR analysis, tert-butoxycarboxyl groups can be transformed into the -COOH ones by eliminating gaseous isobutylene after thermal annealing of pDPPBu-BT thin film at 240 °C. The FET with the thermally treated thin film of pDPPBu-BT displays remarkably sensitive and selective response toward ammonia and volatile amines. This can be attributed to the fact that the elimination of gaseous isobutylene accompanies the formation of nanopores with the thin film, which will facilitate the diffusion and interaction of ammonia and other amines with the semiconducting layer, leading to high sensitivity and fast response for this FET sensor. This FET sensor can detect ammonia down to 10 ppb and the interferences from other volatile analytes except amines can be negligible.

A peptide derivatized cellulosic aerogel from cotton as a point of care diagnostic protease sensor

USDA-ARS?s Scientific Manuscript database

Lightweight aerogels are highly porous with usually very small pore size making them suitable for a variety of potential applications as sensors including deformation strain, humidity, organic vapors, thermal, and optical sensing properties. However, little has been reported on their use as biosenso...

Characterizing Semiconductor Alloys for Infrared Sensors

NASA Technical Reports Server (NTRS)

Lehoczky, B. S. L.; Szofran, F. R.; Martin, B. G.

1986-01-01

Report presents results of continuing program aimed at characterizing mercury/cadmium/tellurium alloys and eventually developing improved methods of preparing alloys for use as infrared sensors. Work covered by report includes series of differential thermal analysis (DTA) measurements of alloy compositions with x varied from 9 to 1 in 0.1 increments.

Time-Separating Heating and Sensor Functions of Thermistors in Precision Thermal Control Applications

NASA Technical Reports Server (NTRS)

Cho, Hyung J.; Sukhatme, Kalyani G.; Mahoney, John C.; Penanen, Konstantin Penanen; Vargas, Rudolph, Jr.

2010-01-01

A method allows combining the functions of a heater and a thermometer in a single device, a thermistor, with minimal temperature read errors. Because thermistors typically have a much smaller thermal mass than the objects they monitor, the thermal time to equilibrate the thermometer to the temperature of the object is typically much shorter than the thermal time of the object to change its temperature in response to an external perturbation.

Ultrathin Injectable Sensors of Temperature, Thermal Conductivity, and Heat Capacity for Cardiac Ablation Monitoring.

PubMed

Koh, Ahyeon; Gutbrod, Sarah R; Meyers, Jason D; Lu, Chaofeng; Webb, Richard Chad; Shin, Gunchul; Li, Yuhang; Kang, Seung-Kyun; Huang, Yonggang; Efimov, Igor R; Rogers, John A

2016-02-04

Knowledge of the distributions of temperature in cardiac tissue during and after ablation is important in advancing a basic understanding of this process, and for improving its efficacy in treating arrhythmias. Technologies that enable real-time temperature detection and thermal characterization in the transmural direction can help to predict the depths and sizes of lesion that form. Herein, materials and designs for an injectable device platform that supports precision sensors of temperature and thermal transport properties distributed along the length of an ultrathin and flexible needle-type polymer substrate are introduced. The resulting system can insert into the myocardial tissue, in a minimally invasive manner, to monitor both radiofrequency ablation and cryoablation, in a manner that has no measurable effects on the natural mechanical motions of the heart. The measurement results exhibit excellent agreement with thermal simulations, thereby providing improved insights into lesion transmurality. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of Water Absorption and Diffusion in Microparticles Containing Xylitol to Provide a Cooling Effect by Thermal Analysis

NASA Astrophysics Data System (ADS)

Salaün, F.; Bedek, G.; Devaux, E.; Dupont, D.; Deranton, D.

2009-08-01

Polyurethane microparticles containing xylitol as a sweat sensor system were prepared by interfacial polymerization. The structural and thermal properties of the resultant microparticles were studied. The surface morphology and chemical structure of microparticles were investigated using an optical microscope (OM) and a Fourier-transform infrared spectroscope (FTIR), respectively. The thermal properties of samples were investigated by thermogravimetric analysis (TGA) and by differential scanning calorimetry (DSC). Thus, two types of microparticles were synthesized by varying the percentage of monomers introduced. The obtained morphology is directly related to the synthesis conditions. DSC analysis indicated that the mass content of crystalline xylitol was up to 63.8 %, which resulted in a high enthalpy of dilution of 127.7 J · g-1. Furthermore, the water release rate monitored by TGA analysis was found to be faster from the microparticles than from raw xylitol. Thus, the microparticles could be applied for thermal energy storage and moisture sensor enhancement.

Graphene/elastomer composite-based photo-thermal nanopositioners

PubMed Central

Loomis, James; Fan, Xiaoming; Khosravi, Farhad; Xu, Peng; Fletcher, Micah; Cohn, Robert W.; Panchapakesan, Balaji

2013-01-01

The addition of nanomaterials to polymers can result not only in significant material property improvements, but also assist in creating entirely new composite functionalities. By dispersing graphene nanoplatelets (GNPs) within a polydimethylsiloxane matrix, we show that efficient light absorption by GNPs and subsequent energy transduction to the polymeric chains can be used to controllably produce significant amounts of motion through entropic elasticity of the pre-strained composite. Using dual actuators, a two-axis sub-micron resolution stage was developed, and allowed for two-axis photo-thermal positioning (~100 μm per axis) with 120 nm resolution (feedback sensor limitation), and ~5 μm/s actuation speeds. A PID control loop automatically stabilizes the stage against thermal drift, as well as random thermal-induced position fluctuations (up to the bandwidth of the feedback and position sensor). Maximum actuator efficiency values of ~0.03% were measured, approximately 1000 times greater than recently reported for light-driven polymer systems. PMID:23712601