Magnetic field sensor for isotropically sensing an incident magnetic field in a sensor plane

NASA Technical Reports Server (NTRS)

Pant, Bharat B. (Inventor); Wan, Hong (Inventor)

2001-01-01

A magnetic field sensor that isotropically senses an incident magnetic field. This is preferably accomplished by providing a magnetic field sensor device that has one or more circular shaped magnetoresistive sensor elements for sensing the incident magnetic field. The magnetoresistive material used is preferably isotropic, and may be a CMR material or some form of a GMR material. Because the sensor elements are circular in shape, shape anisotropy is eliminated. Thus, the resulting magnetic field sensor device provides an output that is relatively independent of the direction of the incident magnetic field in the sensor plane.

Lightning Protection and Detection System

NASA Technical Reports Server (NTRS)

Mielnik, John J. (Inventor); Woodard, Marie (Inventor); Smith, Laura J. (Inventor); Wang, Chuantong (Inventor); Koppen, Sandra V. (Inventor); Dudley, Kenneth L. (Inventor); Szatkowski, George N. (Inventor); Nguyen, Truong X. (Inventor); Ely, Jay J. (Inventor)

2017-01-01

A lightning protection and detection system includes a non-conductive substrate material of an apparatus; a sensor formed of a conductive material and deposited on the non-conductive substrate material of the apparatus. The sensor includes a conductive trace formed in a continuous spiral winding starting at a first end at a center region of the sensor and ending at a second end at an outer corner region of the sensor, the first and second ends being open and unconnected. An electrical measurement system is in communication with the sensor and receives a resonant response from the sensor, to perform detection, in real-time, of lightning strike occurrences and damage therefrom to the sensor and the non-conductive substrate material.

Resistive oxygen sensor using ceria-zirconia sensor material and ceria-yttria temperature compensating material for lean-burn engine.

PubMed

Izu, Noriya; Nishizaki, Sayaka; Shin, Woosuck; Itoh, Toshio; Nishibori, Maiko; Matsubara, Ichiro

2009-01-01

Temperature compensating materials were investigated for a resistive oxygen sensor using Ce(0.9)Zr(0.1)O(2) as a sensor material for lean-burn engines. The temperature dependence of a temperature compensating material should be the same as the sensor material; therefore, the Y concentration in CeO(2)-Y(2)O(3) was optimized. The resistance of Ce(0.5)Y(0.5)O(2-δ) was independent of the air-to-fuel ratio (oxygen partial pressure), so that it was confirmed to function as a temperature compensating material. Sensor elements comprised of Ce(0.9)Zr(0.1)O(2) and Ce(0.5)Y(0.5)O(2-δ) were fabricated and the output was determined to be approximately independent of the temperature in the wide range from 773 to 1,073 K.

Optimization of the coplanar interdigital capacitive sensor

NASA Astrophysics Data System (ADS)

Huang, Yunzhi; Zhan, Zheng; Bowler, Nicola

2017-02-01

Interdigital capacitive sensors are applied in nondestructive testing and material property characterization of low-conductivity materials. The sensor performance is typically described based on the penetration depth of the electric field into the sample material, the sensor signal strength and its sensitivity. These factors all depend on the geometry and material properties of the sensor and sample. In this paper, a detailed analysis is provided, through finite element simulations, of the ways in which the sensor's geometrical parameters affect its performance. The geometrical parameters include the number of digits forming the interdigital electrodes and the ratio of digit width to their separation. In addition, the influence of the presence or absence of a metal backplane on the sample is analyzed. Further, the effects of sensor substrate thickness and material on signal strength are studied. The results of the analysis show that it is necessary to take into account a trade-off between the desired sensitivity and penetration depth when designing the sensor. Parametric equations are presented to assist the sensor designer or nondestructive evaluation specialist in optimizing the design of a capacitive sensor.

[Comparison of the Cost-Effectiveness of the SOX and COX Regimens in Patients with Unresectable Advanced and Recurrent Colorectal Cancer Using a Clinical Decision Analysis Approach].

PubMed

Nagase, Satoshi; Iyoda, Tomokazu; Kanno, Hiroshi; Akase, Tomohide; Arakawa, Ichiro; Inoue, Tadao; Uetsuka, Yoshio

2016-10-01

Phase III clinical trials have comfirmed that the S-1 plus oxaliplatin(SOX)is inferior to the capecitabine plus oxaliplatin (COX)regimen in the treatment of metastatic colorectal cancer.On the basis of these findings, we compared, using a clinical decision analysis-based approach, the cost-effectiveness of the SOX and COX regimens.Herein, we simulated the expected effects and costs of the SOX and COX regimens using the markov model.Clinical data were obtained from Hong's 2012 report.The cost data comprised the costs for pharmacist labor, material, inspection, and treatment for adverse event, as well as the total cost of care at the advanced stage.The result showed that the expected cost of the SOX and COX regimen was 1,538,330 yen, and 1,429,596 yen, respectively, with an expected survival rate of 29.18 months, and 28.63 months, respectively.The incremental cost-effectiveness ratio of the SOX regimen was 197,698 yen/month; thus, the SOX regimen was found to be more cost-effective that the COX regimen.

Optimization of sensor introduction into laminated composite materials

NASA Astrophysics Data System (ADS)

Schaaf, Kristin; Nemat-Nasser, Sia

2008-03-01

This work seeks to extend the functionality of the composite material beyond that of simply load-bearing and to enable in situ sensing, without compromising the structural integrity of the host composite material. Essential to the application of smart composites is the issue of the mechanical coupling of the sensor to the host material. Here we present various methods of embedding sensors within the host composite material. In this study, quasi-static three-point bending (short beam) and fatigue three-point bending (short beam) tests are conducted in order to characterize the effects of introducing the sensors into the host composite material. The sensors that are examined include three types of polyvinylidene fluoride (PVDF) thin film sensors: silver ink with a protective coating of urethane, silver ink without a protective coating, and nickel-copper alloy without a protective coating. The methods of sensor integration include placement at the midplane between the layers of prepreg material as well as a sandwich configuration in which a PVDF thin film sensor is placed between the first and second and nineteenth and twentieth layers of prepreg. Each PVDF sensor is continuous and occupies the entire layer, lying in the plane normal to the thickness direction in laminated composites. The work described here is part of an ongoing effort to understand the structural effects of integrating microsensor networks into a host composite material.

Magnetic Sensors Based on Amorphous Ferromagnetic Materials: A Review

PubMed Central

Morón, Carlos; Cabrera, Carolina; Morón, Alberto; García, Alfonso; González, Mercedes

2015-01-01

Currently there are many types of sensors that are used in lots of applications. Among these, magnetic sensors are a good alternative for the detection and measurement of different phenomena because they are a “simple” and readily available technology. For the construction of such devices there are many magnetic materials available, although amorphous ferromagnetic materials are the most suitable. The existence in the market of these materials allows the production of different kinds of sensors, without requiring expensive manufacture investments for the magnetic cores. Furthermore, these are not fragile materials that require special care, favouring the construction of solid and reliable devices. Another important feature is that these sensors can be developed without electric contact between the measuring device and the sensor, making them especially fit for use in harsh environments. In this review we will look at the main types of developed magnetic sensors. This work presents the state of the art of magnetic sensors based on amorphous ferromagnetic materials used in modern technology: security devices, weapon detection, magnetic maps, car industry, credit cards, etc. PMID:26569244

Magnetic Sensors Based on Amorphous Ferromagnetic Materials: A Review.

PubMed

Morón, Carlos; Cabrera, Carolina; Morón, Alberto; García, Alfonso; González, Mercedes

2015-11-11

Currently there are many types of sensors that are used in lots of applications. Among these, magnetic sensors are a good alternative for the detection and measurement of different phenomena because they are a "simple" and readily available technology. For the construction of such devices there are many magnetic materials available, although amorphous ferromagnetic materials are the most suitable. The existence in the market of these materials allows the production of different kinds of sensors, without requiring expensive manufacture investments for the magnetic cores. Furthermore, these are not fragile materials that require special care, favouring the construction of solid and reliable devices. Another important feature is that these sensors can be developed without electric contact between the measuring device and the sensor, making them especially fit for use in harsh environments. In this review we will look at the main types of developed magnetic sensors. This work presents the state of the art of magnetic sensors based on amorphous ferromagnetic materials used in modern technology: security devices, weapon detection, magnetic maps, car industry, credit cards, etc.

Biological and chemical sensors based on graphene materials.

PubMed

Liu, Yuxin; Dong, Xiaochen; Chen, Peng

2012-03-21

Owing to their extraordinary electrical, chemical, optical, mechanical and structural properties, graphene and its derivatives have stimulated exploding interests in their sensor applications ever since the first isolation of free-standing graphene sheets in year 2004. This article critically and comprehensively reviews the emerging graphene-based electrochemical sensors, electronic sensors, optical sensors, and nanopore sensors for biological or chemical detection. We emphasize on the underlying detection (or signal transduction) mechanisms, the unique roles and advantages of the used graphene materials. Properties and preparations of different graphene materials, their functionalizations are also comparatively discussed in view of sensor development. Finally, the perspective and current challenges of graphene sensors are outlined (312 references).

Toward high value sensing: monolayer-protected metal nanoparticles in multivariable gas and vapor sensors.

PubMed

Potyrailo, Radislav A

2017-08-29

For detection of gases and vapors in complex backgrounds, "classic" analytical instruments are an unavoidable alternative to existing sensors. Recently a new generation of sensors, known as multivariable sensors, emerged with a fundamentally different perspective for sensing to eliminate limitations of existing sensors. In multivariable sensors, a sensing material is designed to have diverse responses to different gases and vapors and is coupled to a multivariable transducer that provides independent outputs to recognize these diverse responses. Data analytics tools provide rejection of interferences and multi-analyte quantitation. This review critically analyses advances of multivariable sensors based on ligand-functionalized metal nanoparticles also known as monolayer-protected nanoparticles (MPNs). These MPN sensing materials distinctively stand out from other sensing materials for multivariable sensors due to their diversity of gas- and vapor-response mechanisms as provided by organic and biological ligands, applicability of these sensing materials for broad classes of gas-phase compounds such as condensable vapors and non-condensable gases, and for several principles of signal transduction in multivariable sensors that result in non-resonant and resonant electrical sensors as well as material- and structure-based photonic sensors. Such features should allow MPN multivariable sensors to be an attractive high value addition to existing analytical instrumentation.

Objective Assessment of Fall Risk in Parkinson's Disease Using a Body-Fixed Sensor Worn for 3 Days

PubMed Central

Weiss, Aner; Herman, Talia; Giladi, Nir; Hausdorff, Jeffrey M.

2014-01-01

Background Patients with Parkinson's disease (PD) suffer from a high fall risk. Previous approaches for evaluating fall risk are based on self-report or testing at a given time point and may, therefore, be insufficient to optimally capture fall risk. We tested, for the first time, whether metrics derived from 3 day continuous recordings are associated with fall risk in PD. Methods and Materials 107 patients (Hoehn & Yahr Stage: 2.6±0.7) wore a small, body-fixed sensor (3D accelerometer) on lower back for 3 days. Walking quantity (e.g., steps per 3-days) and quality (e.g., frequency-derived measures of gait variability) were determined. Subjects were classified as fallers or non-fallers based on fall history. Subjects were also followed for one year to evaluate predictors of the transition from non-faller to faller. Results The 3 day acceleration derived measures were significantly different in fallers and non-fallers and were significantly correlated with previously validated measures of fall risk. Walking quantity was similar in the two groups. In contrast, the fallers walked with higher step-to-step variability, e.g., anterior-posterior width of the dominant frequency was larger (p = 0.012) in the fallers (0.78±0.17 Hz) compared to the non-fallers (0.71±0.07 Hz). Among subjects who reported no falls in the year prior to testing, sensor-derived measures predicted the time to first fall (p = 0.0034), whereas many traditional measures did not. Cox regression analysis showed that anterior-posterior width was significantly (p = 0.0039) associated with time to fall during the follow-up period, even after adjusting for traditional measures. Conclusions/Significance These findings indicate that a body-fixed sensor worn continuously can evaluate fall risk in PD. This sensor-based approach was able to identify transition from non-faller to faller, whereas many traditional metrics were not successful. This approach may facilitate earlier detection of fall risk and may in the future, help reduce high costs associated with falls. PMID:24801889

High temperature sensor

DOEpatents

Tokarz, Richard D.

1982-01-01

A high temperature sensor includes a pair of electrical conductors separated by a mass of electrical insulating material. The insulating material has a measurable resistivity within the sensor that changes in relation to the temperature of the insulating material within a high temperature range (1,000 to 2,000 K.). When required, the sensor can be encased within a ceramic protective coating.

Microglia cyclooxygenase-2 activity in experimental gliomas: possible role in cerebral edema formation.

PubMed

Badie, Behnam; Schartner, Jill M; Hagar, Aaron R; Prabakaran, Sakthivel; Peebles, Todd R; Bartley, Becky; Lapsiwala, Samir; Resnick, Daniel K; Vorpahl, Jessica

2003-02-01

Cerebral edema is responsible for significant morbidity and mortality in patients harboring malignant gliomas. To examine the role of inflammatory cells in brain edema formation, we studied the expression cyclooxygenase (COX)-2, a key enzyme in arachidonic acid metabolism, by microglia in the C6 rodent glioma model. The expression of COX-2 in primary microglia cultures obtained from intracranial rat C6 gliomas was examined using reverse transcription-PCR, Western analysis, and prostaglandin E(2) (PGE(2)) enzyme immunoassay. Blood-tumor barrier permeability was studied in the same tumor model using magnetic resonance imaging. In contrast to C6 glioma cells, microglia isolated from intracranial C6 tumors produced high levels of PGE(2) through a COX-2-dependent pathway. To test whether the observed microglia COX-2 activity played a role in brain edema formation in gliomas, tumor-bearing rats were treated with rofecoxib, a selective COX-2 inhibitor. Rofecoxib was as effective as dexamethasone in decreasing the diffusion of contrast material into the brain parenchyma (P = 0.01, rofecoxib versus control animals), suggesting a reduction in blood-tumor barrier permeability. These findings suggest that glioma-infiltrating microglia are a major source of PGE(2) production through the COX-2 pathway and support the use of COX-2 inhibitors as possible alternatives to glucocorticoids in the treatment of peritumoral edema in patients with malignant brain tumors.

Eddy Current Method for Fatigue Testing

NASA Technical Reports Server (NTRS)

Simpson, John W. (Inventor); Fulton, James P. (Inventor); Wincheski, Russell A. (Inventor); Todhunter, Ronald G. (Inventor); Namkung, Min (Inventor); Nath, Shridhar C. (Inventor)

1997-01-01

Flux-focusing electromagnetic sensor using a ferromagnetic flux-focusing lens simplifies inspections and increases detectability of fatigue cracks and material loss in high conductivity material. A ferrous shield isolates a high-turn pick-up coil from an excitation coil. Use of the magnetic shield produces a null voltage output across the receiving coil in presence of an unflawed sample. Redistribution of the current flow in the sample caused by the presence of flaws. eliminates the shielding condition and a large output voltage is produced, yielding a clear unambiguous flaw signal. Maximum sensor output is obtained when positioned symmetrically above the crack. By obtaining position of maximum sensor output, it is possible to track the fault and locate the area surrounding its tip. Accuracy of tip location is enhanced by two unique features of the sensor; a very high signal-to-noise ratio of the probe's output resulting in an extremely smooth signal peak across the fault, and a rapidly decaying sensor output outside a small area surrounding the crack tip enabling the search region to be clearly defined. Under low frequency operation, material thinning due to corrosion causes incomplete shielding of the pick-up coil. Low frequency output voltage of the probe is therefore a direct indicator of thickness of the test sample. Fatigue testing a conductive material is accomplished by applying load to the material, applying current to the sensor, scanning the material with the sensor, monitoring the sensor output signal, adjusting material load based on the sensor output signal of the sensor, and adjusting position of the sensor based on its output signal.

Bioassay-guided supercritical fluid extraction of cyclooxygenase-2 inhibiting substances in Plantago major L.

PubMed

Stenholm, A; Göransson, U; Bohlin, L

2013-02-01

Selective extraction of plant materials is advantageous for obtaining extracts enriched with desired constituents, thereby reducing the need for subsequent chromatography purification. Such compounds include three cyclooxygenase-2 (COX-2) inhibitory substances in Plantago major L. targeted in this investigation: α-linolenic acid (α-LNA) (18:3 ω-3) and the triterpenic acids ursolic acid and oleanolic acid. To investigate the scope for tuning the selectivity of supercritical fluid extraction (SFE) using bioassay guidance, and Soxhlet extraction with dichloromethane as solvent as a reference technique, to optimise yields of these substances. Extraction parameters were varied to optimise extracts' COX-2/COX-1 inhibitory effect ratios. The crude extracts were purified initially using a solid phase extraction (SPE) clean-up procedure and the target compounds were identified with GC-MS, LC-ESI-MS and LC-ESI-MS² using GC-FID for quantification. α-LNA was preferentially extracted in dynamic mode using unmodified carbon dioxide at 40°C and 172 bar, at a 0.04% (w/w) yield with a COX-2/COX-1 inhibitory effect ratio of 1.5. Ursolic and oleanolic acids were dynamically extracted at 0.25% and 0.06% yields, respectively, with no traces of (α-LNA) and a COX-2/COX-1-inhibitory effect ratio of 1.1 using 10% (v/v) ethanol as polar modifier at 75°C and 483 bar. The Soxhlet extracts had ursolic acid, oleanolic acid and αLNA yields up to 1.36%, 0.34% and 0.15%, respectively, with a COX-2/COX-1 inhibitory effect ratio of 1.2. The target substances can be extracted selectively by bioassay guided optimisation of SFE conditions. Copyright © 2012 John Wiley & Sons, Ltd.

Radiation Therapy Overcomes Adverse Prognostic Role of Cyclooxygenase-2 Expression on Reed-Sternberg Cells in Early Hodgkin Lymphoma

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

Mestre, Francisco; Gutiérrez, Antonio, E-mail: antoniom.gutierrez@ssib.es; Rodriguez, Jose

Purpose: To analyze the role of radiation therapy (RT) on the adverse prognostic influence of cyclooxygenase-2 (COX-2) expression on Reed-Sternberg (RS) cells, in the setting of early Hodgkin lymphoma (HL) treated with ABVD (adriamycin, vinblastine, bleomycin, dacarbazine). Methods and Materials: In the present study we retrospectively investigated the prognostic value of COX-2 expression in a large (n=143), uniformly treated early HL population from the Spanish Network of HL using tissue microarrays. Univariate and multivariate analyses were done, including the most recognized clinical variables and the potential role of administration of adjuvant RT. Results: Median age was 31 years; the expression of COX-2more » defined a subgroup with significantly worse prognosis. Considering COX-2{sup +} patients, those who received RT had significantly better 5-year progression-free survival (PFS) (80% vs 54% if no RT; P=.008). In contrast, COX-2{sup −} patients only had a modest, nonsignificant benefit from RT in terms of 5-year PFS (90% vs 79%; P=.13). When we compared the outcome of patients receiving RT considering the expression of COX-2 on RS cells, we found a nonsignificant 10% difference in terms of PFS between COX-2{sup +} and COX-2{sup −} patients (P=.09), whereas the difference between the 2 groups was important (25%) in patients not receiving RT (P=.04). Conclusions: Cyclooxygenase-2 RS cell expression is an adverse independent prognostic factor in early HL. Radiation therapy overcomes the worse prognosis associated with COX-2 expression on RS cells, acting in a chemotherapy-independent way. Cyclooxygenase-2 RS cell expression may be useful for determining patient candidates with early HL to receive consolidation with RT.« less

High-temperature sensor

DOEpatents

Not Available

1981-01-29

A high temperature sensor is described which includes a pair of electrical conductors separated by a mass of electrical insulating material. The insulating material has a measurable resistivity within the sensor that changes in relation to the temperature of the insulating material within a high temperature range (1000 to 2000/sup 0/K). When required, the sensor can be encased within a ceramic protective coating.

IR-Sensography™—expanding the scope of contact-free sensing methods

NASA Astrophysics Data System (ADS)

Klein, Jens; Schunk, Stephan A.

2005-01-01

Capturing the response of one or more sensor materials is conventionally performed by the direct transformation of a chemical or physico-chemical signal into an electrical one. With an increasing number of sensor materials within an arrangement of sensor elements or a sensor array, problems such as contacting each single sensor, signal processing and resistance against cross-talk, harsh conditions such as corrosive atmospheres, etc are limiting factors for the further development of so-called 'chemical noses'. State-of-the-art and commercially available are arrays of eight different sensor materials, literature known in another context are sensor arrays with 256 materials on a silicon wafer, which are contacted via electrical conduits. We present here the concept of the IR-Sensography™, the use of an IR-camera as an external detector system for sensor libraries. Acting like an optical detection method, the IR-camera detects small temperature changes due to physisorption, chemisorption or other forms of interaction or reaction as an output signal in the form of radiation emitted by the multiplicity of sensor materials simultaneously. The temperature resolution of commercially available IR-camera systems can be tuned to the range below 0.1 K. Due to the separation of sensors and the detector device, reaction conditions at the sensor locus can be adapted to the analytical problem and do not need to take care of other boundary conditions which come into play with the analytical device, e.g. the IR-camera. Calibration or regeneration steps can as well be performed over the multiplicity of all sensor materials. Any given chemical compound that comes into contact with the sensor through the passing fluids will result in a specific activity pattern on a spatially fixed library of sensor materials that is unique for the given compound. While the pattern therefore serves as an identifier, the intensity of the pattern represents the quantitative amount of this compound in the mixture. For proof-of-concept experiments we used a 96-fold-sensing device. The sensor library consists of seven different material classes, all synthesized via classical impregnation techniques in different compositions on multihole monolithic ceramic supports (93 different materials based on different concentrations of binary/ternary mixtures of transition metals, three inert materials). We demonstrate with these results the wide range of capabilities for the IR-Sensography™. Both the qualitative and the quantitative determinations of molecules in the gas phase can be performed with this new methodology.

Engineering the Electronic Structure of 2D WS2 Nanosheets Using Co Incorporation as Cox W(1- x ) S2 for Conspicuously Enhanced Hydrogen Generation.

PubMed

Shifa, Tofik Ahmed; Wang, Fengmei; Liu, Kaili; Xu, Kai; Wang, Zhenxing; Zhan, Xueying; Jiang, Chao; He, Jun

2016-07-01

Transition metal dichalcogenides (TMDs), as one of potential electrocatalysts for hydrogen evolution reaction (HER), have been extensively studied. Such TMD-based ternary materials are believed to engender optimization of hydrogen adsorption free energy to thermoneutral value. Theoretically, cobalt is predicted to actively promote the catalytic activity of WS2 . However, experimentally it requires systematic approach to form Cox W(1- x ) S2 without any concomitant side phases that are detrimental for the intended purpose. This study reports a rational method to synthesize pure ternary Cox W(1- x ) S2 nanosheets for efficiently catalyzing HER. Benefiting from the modification in the electronic structure, the resultant material requires overpotential of 121 mV versus reversible hydrogen electrode (RHE) to achieve current density of 10 mA cm(-2) and shows Tafel slope of 67 mV dec(-1) . Furthermore, negligible loss of activity is observed over continues electrolysis of up to 2 h demonstrating its fair stability. The finding provides noticeable experimental support for other computational reports and paves the way for further works in the area of HER catalysis based on ternary materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Feasibility study on measuring axial and transverse stress/strain components in composite materials using Bragg sensors

NASA Astrophysics Data System (ADS)

Luyckx, G.; Degrieck, J.; De Waele, W.; Van Paepegem, W.; Van Roosbroeck, J.; Chah, K.; Vlekken, J.; McKenzie, I.; Obst, A.

2017-11-01

A fibre optic sensor design is proposed for simultaneously measuring the 3D stress (or strain) components and temperature inside thermo hardened composite materials. The sensor is based on two fibre Bragg gratings written in polarisation maintaining fibre. Based on calculations of the condition number, it will be shown that reasonable accuracies are to be expected. First tests on the bare sensors and on the sensors embedded in composite material, which confirm the expected behaviour, will be presented.

Material condition assessment with eddy current sensors

NASA Technical Reports Server (NTRS)

Goldfine, Neil J. (Inventor); Washabaugh, Andrew P. (Inventor); Sheiretov, Yanko K. (Inventor); Schlicker, Darrell E. (Inventor); Lyons, Robert J. (Inventor); Windoloski, Mark D. (Inventor); Craven, Christopher A. (Inventor); Tsukernik, Vladimir B. (Inventor); Grundy, David C. (Inventor)

2010-01-01

Eddy current sensors and sensor arrays are used for process quality and material condition assessment of conducting materials. In an embodiment, changes in spatially registered high resolution images taken before and after cold work processing reflect the quality of the process, such as intensity and coverage. These images also permit the suppression or removal of local outlier variations. Anisotropy in a material property, such as magnetic permeability or electrical conductivity, can be intentionally introduced and used to assess material condition resulting from an operation, such as a cold work or heat treatment. The anisotropy is determined by sensors that provide directional property measurements. The sensor directionality arises from constructs that use a linear conducting drive segment to impose the magnetic field in a test material. Maintaining the orientation of this drive segment, and associated sense elements, relative to a material edge provides enhanced sensitivity for crack detection at edges.

Magnetic sensor for high temperature using a laminate composite of magnetostrictive material and piezoelectric material

NASA Astrophysics Data System (ADS)

Ueno, Toshiyuki; Higuchi, Toshiro

2005-05-01

A high sensitive and heat-resistive magnetic sensor using a magnetostrictive/piezoelectric laminate composite is investigated. The sensing principle is based on the magnetostrictive- and piezoelectric effect, whereby a detected yoke displacement is transduced into a voltage on the piezoelectric materials. The sensor is intended to detect the displacement of a ferromagnetic object in a high temperature environment, where conventional magnetic sensors are not useful. Such applications include sensors in engine of automobile and machinery used in material processing. The sensor features combination of a laminate composite of magnetostrictive/piezoelectric materials with high Curie temperatures and an appropriate magnetic circuit to convert mechanical displacement to sensor voltages and suppress temperature fluctuation. This paper describes the sensing principle and shows experimental results using a composite of Terfenol-D and Lithium Niobate to assure high sensitivity of 50V/mm at bias gap of 0.1mm and a temperature operating range over 200 °C.

Low-Temperature Solution Processable Electrodes for Piezoelectric Sensors Applications

NASA Astrophysics Data System (ADS)

Tuukkanen, Sampo; Julin, Tuomas; Rantanen, Ville; Zakrzewski, Mari; Moilanen, Pasi; Lupo, Donald

2013-05-01

Piezoelectric thin-film sensors are suitable for a wide range of applications from physiological measurements to industrial monitoring systems. The use of flexible materials in combination with high-throughput printing technologies enables cost-effective manufacturing of custom-designed, highly integratable piezoelectric sensors. This type of sensor can, for instance, improve industrial process control or enable the embedding of ubiquitous sensors in our living environment to improve quality of life. Here, we discuss the benefits, challenges and potential applications of piezoelectric thin-film sensors. The piezoelectric sensor elements are fabricated by printing electrodes on both sides of unmetallized poly(vinylidene fluoride) film. We show that materials which are solution processable in low temperatures, biocompatible and environmental friendly are suitable for use as electrode materials in piezoelectric sensors.

Advanced Metalworking Solutions for Naval Systems That Go in Harm’s Way.

DTIC Science & Technology

2011-01-01

Cox, Titanium Fabrication Corporation, MMC, NSWCCD, ABS, and NMC. Navy Metalworking Center • Advanced Metallic Materials NMC has a successful record...Current efforts involve titanium , high-strength steel, and other alternate materials. 4 ADVANcED METALLic MATEriALS A cost-effective manufacturing solution...Manufacturing and Sustainment Technologies (iMAST). Improved shaft cladding materials and processes, which will increase the life of the main propulsion

Thin-film fiber optic hydrogen and temperature sensor system

DOEpatents

Nave, Stanley E.

1998-01-01

The invention discloses a sensor probe device for monitoring of hydrogen gas concentrations and temperatures by the same sensor probe. The sensor probe is constructed using thin-film deposition methods for the placement of a multitude of layers of materials sensitive to hydrogen concentrations and temperature on the end of a light transparent lens located within the sensor probe. The end of the lens within the sensor probe contains a lens containing a layer of hydrogen permeable material which excludes other reactive gases, a layer of reflective metal material that forms a metal hydride upon absorbing hydrogen, and a layer of semi-conducting solid that is transparent above a temperature dependent minimum wavelength for temperature detection. The three layers of materials are located at the distal end of the lens located within the sensor probe. The lens focuses light generated by broad-band light generator and connected by fiber-optics to the sensor probe, onto a reflective metal material layer, which passes through the semi-conducting solid layer, onto two optical fibers located at the base of the sensor probe. The reflected light is transmitted over fiberoptic cables to a spectrometer and system controller. The absence of electrical signals and electrical wires in the sensor probe provides for an elimination of the potential for spark sources when monitoring in hydrogen rich environments, and provides a sensor free from electrical interferences.

Thin-film fiber optic hydrogen and temperature sensor system

DOEpatents

Nave, S.E.

1998-07-21

The invention discloses a sensor probe device for monitoring of hydrogen gas concentrations and temperatures by the same sensor probe. The sensor probe is constructed using thin-film deposition methods for the placement of a multitude of layers of materials sensitive to hydrogen concentrations and temperature on the end of a light transparent lens located within the sensor probe. The end of the lens within the sensor probe contains a lens containing a layer of hydrogen permeable material which excludes other reactive gases, a layer of reflective metal material that forms a metal hydride upon absorbing hydrogen, and a layer of semi-conducting solid that is transparent above a temperature dependent minimum wavelength for temperature detection. The three layers of materials are located at the distal end of the lens located within the sensor probe. The lens focuses light generated by broad-band light generator and connected by fiber-optics to the sensor probe, onto a reflective metal material layer, which passes through the semi-conducting solid layer, onto two optical fibers located at the base of the sensor probe. The reflected light is transmitted over fiber optic cables to a spectrometer and system controller. The absence of electrical signals and electrical wires in the sensor probe provides for an elimination of the potential for spark sources when monitoring in hydrogen rich environments, and provides a sensor free from electrical interferences. 3 figs.

A High Pressure Flowing Oil Switch For Gigawatt, Repetitive Applications

DTIC Science & Technology

2005-06-01

for testing the high pressure switch concept under repetitive pulse conditions is a 4.8 Ω, 70 ns water pulse forming line (PFL). The water PFL is...Cox Instruments. A pair of Hedland variable area flow sensors monitored relative flow rates in the two oil lines that fed the high pressure switch . High... pressure switch was tested under both single shot and repetitive conditions over a range of pressures, flow rates and temperatures. The primary

Control of Co content and SOFC cathode performance in Y1-ySr2+yCu3-xCoxO7+δ

NASA Astrophysics Data System (ADS)

Šimo, F.; Payne, J. L.; Demont, A.; Sayers, R.; Li, Ming; Collins, C. M.; Pitcher, M. J.; Claridge, J. B.; Rosseinsky, M. J.

2014-11-01

The electrochemical performance of the layered perovskite YSr2Cu3-xCoxO7+δ, a potential solid oxide fuel cell (SOFC) cathode, is improved by increasing the Co content from x = 1.00 to a maximum of x = 1.30. Single phase samples with x > 1.00 are obtained by tuning the Y/Sr ratio, yielding the composition Y1-ySr2+yCu3-xCoxO7+δ (where y ≤ 0.05). The high temperature structure of Y0.95Sr2.05Cu1.7Co1.3O7+δ at 740 °C is characterised by powder neutron diffraction and the potential of this Co-enriched material as a SOFC cathode is investigated by combining AC impedance spectroscopy, four-probe DC conductivity and powder XRD measurements to determine its electrochemical properties along with its thermal stability and compatibility with a range of commercially available electrolytes. The material is shown to be compatible with doped ceria electrolytes at 900 °C.

Passive absolute age and temperature history sensor

DOEpatents

Robinson, Alex; Vianco, Paul T.

2015-11-10

A passive sensor for historic age and temperature sensing, including a first member formed of a first material, the first material being either a metal or a semiconductor material and a second member formed of a second material, the second material being either a metal or a semiconductor material. A surface of the second member is in contact with a surface of the first member such that, over time, the second material of the second member diffuses into the first material of the first member. The rate of diffusion for the second material to diffuse into the first material depends on a temperature of the passive sensor. One of the electrical conductance, the electrical capacitance, the electrical inductance, the optical transmission, the optical reflectance, or the crystalline structure of the passive sensor depends on the amount of the second material that has diffused into the first member.

Gas sensors based on carbon nanoflake/tin oxide composites for ammonia detection.

PubMed

Lee, Soo-Keun; Chang, Daeic; Kim, Sang Wook

2014-03-15

Carbon nanoflake (CNFL) was obtained from graphite pencil by using the electrochemical method and the CNFL/SnO2 composite material assessed its potential as an ammonia gas sensor. A thin film resistive gas sensor using the composite material was manufactured by the drop casting method, and the sensor was evaluated to test in various ammonia concentrations and operating temperatures. Physical and chemical characteristics of the composite material were assessed using SEM, TEM, SAED, EDS and Raman spectroscopy. The composite material having 10% of SnO2 showed 3 times higher sensor response and better repeatability than the gas sensor using pristine SnO2 nano-particle at the optimal temperature of 350°C. Copyright © 2013 Elsevier B.V. All rights reserved.

Fiber optic gas sensor

NASA Technical Reports Server (NTRS)

Chen, Peng (Inventor); Buric, Michael P. (Inventor); Swinehart, Philip R. (Inventor); Maklad, Mokhtar S. (Inventor)

2010-01-01

A gas sensor includes an in-fiber resonant wavelength device provided in a fiber core at a first location. The fiber propagates a sensing light and a power light. A layer of a material is attached to the fiber at the first location. The material is able to absorb the gas at a temperature dependent gas absorption rate. The power light is used to heat the material and increases the gas absorption rate, thereby increasing sensor performance, especially at low temperatures. Further, a method is described of flash heating the gas sensor to absorb more of the gas, allowing the sensor to cool, thereby locking in the gas content of the sensor material, and taking the difference between the starting and ending resonant wavelengths as an indication of the concentration of the gas in the ambient atmosphere.

PREFACE: 8th Ibero-American Congress on Sensors (IBERSENSOR 2012)

NASA Astrophysics Data System (ADS)

Ramos, Idalia; Santiago-Avilés, Jorge J.

2013-03-01

The 8th Ibero-American Congress on Sensors (IBERSENSOR 2012) was held in Carolina, Puerto Rico on 16-19 October 2012. IBERSENSOR is a forum of the Spanish and Portuguese speaking scientific community, working in the fields of sensors of every possible kind and their applications. Previous conferences in the series were successfully carried out in La Habana, Cuba (1998); Buenos Aires, Argentina (2000); Lima, Perú (2002); Puebla, México (2004); Montevideo, Uruguay (2006); Sao Paulo, Brasil (2008) and Lisboa, Portugal (2010). IBERSENSOR 2012 participants included researchers from eleven countries in the Americas and Europe, in particular young men and women. The conference was organized and sponsored by the Partnership for Research and Education in Materials (NSF-DMR-0934195) a collaborative program between the University of Puerto Rico at Humacao (UPRH) and the University of Pennsylvania (PENN) Materials Research Science and Engineering Center, sponsored by the USA National Science Foundation (NSF). Other sponsors included the Center for Advanced Nanoscale Materials of the University of Puerto Rico at Río Piedras and the Nano/Bio Interface Center (NBIC) at PENN. The Proceedings of IBERSENSOR 2012 include a selection of 21 research papers in the areas of Materials and Processes for Sensor Development, Nano-Sensors, Chemical Sensors, Mechanical Sensors, Optical Sensors, Wireless Sensors, Sensor signal conditioning and Instrumentation, Microfluidic Devices, and Biomedical and Environmental Applications. Editors Idalia Ramos University of Puerto Rico at Humacao, Puerto Rico Jorge J Santiago-Avilés University of Pennsylvania, USA Group photograph Logos Ibero-American Congress on Sensors Ibero-American Congress on Sensors (Ibersensor) Main Sponsors PENN-UPRH-PREM Partnership for Research and Education in Materials (PENN-UPRH-PREM) University of Puerto Rico at Humacao USA National Science Foundation USA National Science Foundation Other Sponsors Center for Advanced Nanoscale Materials Center for Advanced Nanoscale Materials (CNM), University of Puerto Rico, Río Piedras Nano/Bio Interface Center Nano/Bio Interface Center, University of Pennsylvania

Hydrocarbon sensors and materials therefor

DOEpatents

Pham, Ai Quoc; Glass, Robert S.

2000-01-01

An electrochemical hydrocarbon sensor and materials for use in sensors. A suitable proton conducting electrolyte and catalytic materials have been found for specific application in the detection and measurement of non-methane hydrocarbons. The sensor comprises a proton conducting electrolyte sandwiched between two electrodes. At least one of the electrodes is covered with a hydrocarbon decomposition catalyst. Two different modes of operation for the hydrocarbon sensors can be used: equilibrium versus non-equilibrium measurements and differential catalytic. The sensor has particular application for on-board monitoring of automobile exhaust gases to evaluate the performance of catalytic converters. In addition, the sensor can be utilized in monitoring any process where hydrocarbons are exhausted, for instance, industrial power plants. The sensor is low cost, rugged, sensitive, simple to fabricate, miniature, and does not suffer cross sensitivities.

Flexible force sensors for e-textiles

NASA Astrophysics Data System (ADS)

Carvalho, H.; Yao, Y.; Gonçalves, L. M.

2017-10-01

This paper presents the development of inexpensive, lightweight, flexible polymer-based piezoresistive sensors appropriate for integration in e-textiles. The transducing element used is a volume-conductive carbon impregnated black polypropylene/polyethylene film with commercial names Velostat (from 3M) or Linqstat (from Caplinq). The objective is to investigate on the influence of different sensor constructions, varying film thicknesses, electrode materials and encapsulations on sensor performance. Furthermore, ways of integrating the sensors into textile products, as well as potential applications are also studied. In this paper, the behaviour of the sensors under different cyclic compression loads, applied at different speeds, is presented. Sensors using three different electrode materials are tested. The results show significant influence of sensor construction and electrode material on the static and dynamic performance of the devices.

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.

Force sensor using changes in magnetic flux

NASA Technical Reports Server (NTRS)

Pickens, Herman L. (Inventor); Richard, James A. (Inventor)

2012-01-01

A force sensor includes a magnetostrictive material and a magnetic field generator positioned in proximity thereto. A magnetic field is induced in and surrounding the magnetostrictive material such that lines of magnetic flux pass through the magnetostrictive material. A sensor positioned in the vicinity of the magnetostrictive material measures changes in one of flux angle and flux density when the magnetostrictive material experiences an applied force that is aligned with the lines of magnetic flux.

Testing Accuracy of Long-Range Ultrasonic Sensors for Olive Tree Canopy Measurements

PubMed Central

Gamarra-Diezma, Juan Luis; Miranda-Fuentes, Antonio; Llorens, Jordi; Cuenca, Andrés; Blanco-Roldán, Gregorio L.; Rodríguez-Lizana, Antonio

2015-01-01

Ultrasonic sensors are often used to adjust spray volume by allowing the calculation of the crown volume of tree crops. The special conditions of the olive tree require the use of long-range sensors, which are less accurate and faster than the most commonly used sensors. The main objectives of the study were to determine the suitability of the sensor in terms of sound cone determination, angle errors, crosstalk errors and field measurements. Different laboratory tests were performed to check the suitability of a commercial long-range ultrasonic sensor, as were the experimental determination of the sound cone diameter at several distances for several target materials, the determination of the influence of the angle of incidence of the sound wave on the target and distance on the accuracy of measurements for several materials and the determination of the importance of the errors due to interference between sensors for different sensor spacings and distances for two different materials. Furthermore, sensor accuracy was tested under real field conditions. The results show that the studied sensor is appropriate for olive trees because the sound cone is narrower for an olive tree than for the other studied materials, the olive tree canopy does not have a large influence on the sensor accuracy with respect to distance and angle, the interference errors are insignificant for high sensor spacings and the sensor's field distance measurements were deemed sufficiently accurate. PMID:25635414

Embedded Piezoresistive Microcantilever Sensors Functionalized for the Detection of Methyl Salicylate

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

Porter, Timothy L.; Venedam, Richard J.

2013-03-01

Sensors designed to detect the presence of methyl salicylate (MeS) have been tested. These sensors use a sensor platform based on the embedded piezoresistive microcantilever (EPM) design. Sensing materials tested in this study included the polymer poly (ethylene vinyl acetate), or PEVA as well as a composite sensing material consisting of the enzyme SA-binding protein 2, or SABP-2. The SABP-2 was immobilized within a biocompatible Hypol gel matrix. The PEVA-based sensors exhibited slower but reversible responses to MeS vapors, recovering fully to their initial state after the analyte was removed. SABP-2 sensors exhibited faster overall response to the introduction ofmore » MeS, responding nearly instantly. These sensors, however, do not recover after exposures have ended. Sensors using the SABP-2 sensing materials act instead as integrating sensors, measuring irreversibly the total MeS dose obtained.« less

Fabrication of Thin Film Heat Flux Sensors

NASA Technical Reports Server (NTRS)

Will, Herbert A.

1992-01-01

Prototype thin film heat flux sensors have been constructed and tested. The sensors can be applied to propulsion system materials and components. The sensors can provide steady state and fast transient heat flux information. Fabrication of the sensor does not require any matching of the mounting surface. Heat flux is proportional to the temperature difference across the upper and lower surfaces of an insulation material. The sensor consists of an array of thermocouples on the upper and lower surfaces of a thin insulating layer. The thermocouples for the sensor are connected in a thermopile arrangement. A 100 thermocouple pair heat flux sensor has been fabricated on silicon wafers. The sensor produced an output voltage of 200-400 microvolts when exposed to a hot air heat gun. A 20 element thermocouple pair heat flux sensor has been fabricated on aluminum oxide sheet. Thermocouples are Pt-Pt/Rh with silicon dioxide as the insulating material. This sensor produced an output of 28 microvolts when exposed to the radiation of a furnace operating at 1000 C. Work is also underway to put this type of heat flux sensor on metal surfaces.

76 FR 39922 - Notice of Acceptance of Application for Special Nuclear Materials License From Sensor Concepts...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-07

... Application for Special Nuclear Materials License From Sensor Concepts and Applications, Inc., Opportunity To...-4737, or by e-mail to [email protected] . The public version of the Sensor Concepts and Applications... (DNDO) of the U.S. Department of Homeland Security (DHS). Sensor Concepts and Applications (SCA...

Capacity fade of LiNi(1-x-y)CoxAlyO2 cathode for lithium-ion batteries during accelerated calendar and cycle life test. I. Comparison analysis between LiNi(1-x-y)CoxAlyO2 and LiCoO2 cathodes in cylindrical lithium-ion cells during long term storage test

NASA Astrophysics Data System (ADS)

Watanabe, Shoichiro; Kinoshita, Masahiro; Nakura, Kensuke

2014-02-01

Ni-based LiNi(1-x-y)CoxAlyO2 (NCA) and LiCoO2 (LCO) cathode materials taken out of lithium-ion cells after storage for 2 years at 45 °C were analyzed by various spectroscopic techniques. X-ray photoelectron spectroscopy exhibited that there was no difference between NCA and LCO. On the other hand, scanning transmission electron microscopy-electron energy-loss spectroscopy demonstrated there was a remarkably large difference between the two cathode materials. Ni-L2,3 energy-loss near-edge structure (ELNES) spectra of the NCA showed a peak at about 856.5 eV, which was assigned to trivalent nickel, was maintained even after storage, indicating that the NCA had no significant change in its surface structure during storage. On the other hand, in the Co-L2,3 ELNES spectra of the LCO a peak at about 782.5 eV, which was assigned to trivalent cobalt, significantly shifted to the lower energies after storage. These results suggest that crystal structure change of the active material surface is a predominant reason of deterioration during the storage test.

Voltage sensor and dielectric material

DOEpatents

Yakymyshyn, Christopher Paul; Yakymyshyn, Pamela Jane; Brubaker, Michael Allen

2006-10-17

A voltage sensor is described that consists of an arrangement of impedance elements. The sensor is optimized to provide an output ratio that is substantially immune to changes in voltage, temperature variations or aging. Also disclosed is a material with a large and stable dielectric constant. The dielectric constant can be tailored to vary with position or direction in the material.

Special sensors for deformation measurements of different construction materials and structures

NASA Astrophysics Data System (ADS)

Glisic, Branko; Inaudi, Daniele; Kronenberg, Pascal; LLoret, Sandra; Vurpillot, Samuel

1999-05-01

SOFO is a fiber optic sensor system that allows the monitoring of micrometer deformations over measurement bases up to a few meters. It is particularly adapted to measure civil structures built with conventional civil engineering materials (concrete, steel and timber). It has been successfully tested in different types of structures such as bridges, tunnels and piles. The application of the system is however limited in some case when unusual materials are used in the construction and in other cases by the dimensions of standard SOFO sensors. To extend the domain of application of the current system, special sensors have been developed. In this paper we present four special SOFO sensors: long, membrane, thin and stiff sensors. The long sensor has a measurement basis of several tenths of meters and its purpose is the measurement of deformations in massive and large structures (dames, tunnels). The membrane sensor is for use on laminated materials (e.g. membrane roofing) and it is easy to install by simply gluing it to the structure to be monitored. Since standard sensors can not be used for thin mortar layers because of their cross- section, a thin sensor has been developed, too. Finally, the aim of the stiff sensor is to determine the hardening (solidification) time of concrete. This time is determined by comparing the deformations of a stiff and a standard sensor, closely placed in the concrete at the very early age. The design of these sensors is presented along with significant application examples.

Novel Thin Film Sensor Technology for Turbine Engine Hot Section Components

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Fralick, Gustave C.

2007-01-01

Degradation and damage that develops over time in hot section components can lead to catastrophic failure of the turbine section of aircraft engines. A range of thin film sensor technology has been demonstrated enabling on-component measurement of multiple parameters either individually or in sensor arrays including temperature, strain, heat flux, and flow. Conductive ceramics are beginning to be investigated as new materials for use as thin film sensors in the hot section, leveraging expertise in thin films and high temperature materials. The current challenges are to develop new sensor and insulation materials capable of withstanding the extreme hot section environment, and to develop techniques for applying sensors onto complex high temperature structures for aging studies of hot propulsion materials. The technology research and development ongoing at NASA Glenn Research Center for applications to future aircraft, launch vehicles, space vehicles, and ground systems is outlined.

Fiber-optic miniature sensor for in situ temperature monitoring of curing composite material

NASA Astrophysics Data System (ADS)

Sampath, Umesh; Kim, Dae-gil; Kim, Hyunjin; Song, Minho

2018-04-01

This study proposes a fiber-optic temperature sensor with a single-mode fiber tip covered with a thermo-sensitive polymer resin. The temperature is sensed by measuring the Fresnel reflection from the optical fiber/polymer interface. Because the thermo-optic coefficients differ between the optical fiber and the polymer, the in situ temperature can be measured even in curing composite materials. In initial experiments, the proposed sensor successfully measured and recovered the temperature information. The measured sensor data were linearly correlated, with an R2 exceeding 0.99. The standard deviation in the long-term measurements of constant temperature was 2.6%. The durability and stability of the sensor head material in long-term operation was validated by Fourier transform infrared spectroscopy and X-ray diffraction analysis. In further experiments, the suggested miniature temperature sensor obtained the internal temperatures of curing composite material over a wide range (30-110 °C).

Applications of Ionic Liquids for the Development of Optical Chemical Sensors and Biosensors.

PubMed

Muginova, Svetlana V; Myasnikova, Dina A; Kazarian, Sergei G; Shekhovtsova, Tatiana N

2017-01-01

This paper reviews the primary literature reporting the use of ionic liquids (ILs) in optical sensing technologies. The optical chemical sensors that have been developed with the assistance of ILs are classified according to the type of resultant material. Key aspects of applying ILs in such sensors are revealed and discussed. They include using ILs as solvents for the synthesis of sensor matrix materials; additives in polymer matrices; matrix materials; modifiers of the surfaces; and multifunctional sensor components. The operational principles, design, texture, and analytical characteristics of the offered sensors for determining CO 2 , O 2 , metal ions, CN - , and various organic compounds are critically discussed. The key advantages and disadvantages of using ILs in optical sensing technologies are defined. Finally, the applicability of the described materials for chemical analysis is evaluated, and possibilities for their further modernization are outlined.

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

Analytical instrumentation infrastructure for combinatorial and high-throughput development of formulated discrete and gradient polymeric sensor materials arrays

NASA Astrophysics Data System (ADS)

Potyrailo, Radislav A.; Hassib, Lamyaa

2005-06-01

Multicomponent polymer-based formulations of optical sensor materials are difficult and time consuming to optimize using conventional approaches. To address these challenges, our long-term goal is to determine relationships between sensor formulation and sensor response parameters using new scientific methodologies. As the first step, we have designed and implemented an automated analytical instrumentation infrastructure for combinatorial and high-throughput development of polymeric sensor materials for optical sensors. Our approach is based on the fabrication and performance screening of discrete and gradient sensor arrays. Simultaneous formation of multiple sensor coatings into discrete 4×6, 6×8, and 8×12 element arrays (3-15μL volume per element) and their screening provides not only a well-recognized acceleration in the screening rate, but also considerably reduces or even eliminates sources of variability, which are randomly affecting sensors response during a conventional one-at-a-time sensor coating evaluation. The application of gradient sensor arrays provides additional capabilities for rapid finding of the optimal formulation parameters.

Flexural impact force absorption of mouthguard materials using film sensor system.

PubMed

Reza, Fazal; Churei, Hiroshi; Takahashi, Hidekazu; Iwasaki, Naohiko; Ueno, Toshiaki

2014-06-01

Several methods have been used to measure the impact force absorption capacities of mouthguard materials; however, the relationships among these measurement systems have not been clearly determined. The purpose of the present study was to evaluate the impact force-absorbing capability of materials using a drop-ball system with film sensors and load cells to clarify the relationship between these two sensor systems. Disk-shaped specimens (1, 2, and 3 mm thick) were prepared using three commercial thermoplastic mouthguard materials (Bioplast, Impact Guard, MG 21) and one experimental mouthguard material [mixture of Poly (ethyl methacrylate)]. Impact force was applied by letting a stainless steel ball drop free-fall onto the specimens and then measuring the impact load under each specimen using a film sensor system and a load cell sensor system. The total load measured with the film sensor system decreased with an increase in mouthguard thickness, while almost none of the transmitted impact forces measured with the load cell system were statistically different. The film sensor system was considered to be superior to the load cell system because the maximum stress and stress area could be determined. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Active polymer materials for optical fiber CO2 sensors

NASA Astrophysics Data System (ADS)

Wysokiński, Karol; Filipowicz, Marta; Stańczyk, Tomasz; Lipiński, Stanisław; Napierała, Marek; Murawski, Michał; Nasiłowski, Tomasz

2017-04-01

CO2 optical fiber sensors based on polymer active materials are presented in this paper. Ethyl cellulose was proven to be a good candidate for a matrix material of the sensor, since it gives porous, thick and very sensitive layers. Low-cost sensors based on polymer optical fibers have been elaborated. Sensors have been examined for their sensitivity to CO2, temperature and humidity. Response time during cyclic exposures to CO2 have been also determined. Special layers exhibiting irreversible change of color during exposure to carbon dioxide have been developed. They have been verified for a possible use in smart food packaging.

Role of Morphological Structure, Doping, and Coating of Different Materials in the Sensing Characteristics of Humidity Sensors

PubMed Central

Tripathy, Ashis; Pramanik, Sumit; Cho, Jongman; Santhosh, Jayasree; Osman, Noor Azuan Abu

2014-01-01

The humidity sensing characteristics of different sensing materials are important properties in order to monitor different products or events in a wide range of industrial sectors, research and development laboratories as well as daily life. The primary aim of this study is to compare the sensing characteristics, including impedance or resistance, capacitance, hysteresis, recovery and response times, and stability with respect to relative humidity, frequency, and temperature, of different materials. Various materials, including ceramics, semiconductors, and polymers, used for sensing relative humidity have been reviewed. Correlations of the different electrical characteristics of different doped sensor materials as the most unique feature of a material have been noted. The electrical properties of different sensor materials are found to change significantly with the morphological changes, doping concentration of different materials and film thickness of the substrate. Various applications and scopes are pointed out in the review article. We extensively reviewed almost all main kinds of relative humidity sensors and how their electrical characteristics vary with different doping concentrations, film thickness and basic sensing materials. Based on statistical tests, the zinc oxide-based sensing material is best for humidity sensor design since it shows extremely low hysteresis loss, minimum response and recovery times and excellent stability. PMID:25256110

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.

Harsh Environment Silicon Carbide Sensor Technology for Geothermal Instrumentation

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

Pisano, Albert P.

2013-04-26

This project utilizes Silicon Carbide (SiC) materials platform to fabricate advanced sensors to be used as high-temperature downhole instrumentation for the DOE’s Geothermal Technologies Program on Enhanced Geothermal Systems. The scope of the proposed research is to 1) develop a SiC pressure sensor that can operate in harsh supercritical conditions, 2) develop a SiC temperature sensor that can operate in harsh supercritical conditions, 3) develop a bonding process for adhering SiC sensor die to well casing couplers, and 4) perform experimental exposure testing of sensor materials and the sensor devices.

Chemical Detection using Electrically Open Circuits having no Electrical Connections

NASA Technical Reports Server (NTRS)

Woodward, Stanley E.; Olgesby, Donald M.; Taylor, Bryant D.; Shams, Qamar A.

2008-01-01

This paper presents investigations to date on chemical detection using a recently developed method for designing, powering and interrogating sensors as electrically open circuits having no electrical connections. In lieu of having each sensor from a closed circuit with multiple electrically connected components, an electrically conductive geometric pattern that is powered using oscillating magnetic fields and capable of storing an electric field and a magnetic field without the need of a closed circuit or electrical connections is used. When electrically active, the patterns respond with their own magnetic field whose frequency, amplitude and bandwidth can be correlated with the magnitude of the physical quantities being measured. Preliminary experimental results of using two different detection approaches will be presented. In one method, a thin film of a reactant is deposited on the surface of the open-circuit sensor. Exposure to a specific targeted reactant shifts the resonant frequency of the sensor. In the second method, a coating of conductive material is placed on a thin non-conductive plastic sheet that is placed over the surface of the sensor. There is no physical contact between the sensor and the electrically conductive material. When the conductive material is exposed to a targeted reactant, a chemical reaction occurs that renders the material non-conductive. The change in the material s electrical resistance within the magnetic field of the sensor alters the sensor s response bandwidth and amplitude, allowing detection of the reaction without having the reactants in physical contact with the sensor.

Visualizing the Effects of a Positive Early Experience, Tactile Stimulation, on Dendritic Morphology and Synaptic Connectivity with Golgi-Cox Staining

PubMed Central

Mychasiuk, Richelle; Gibb, Robbin; Kolb, Bryan

2013-01-01

To generate longer-term changes in behavior, experiences must be producing stable changes in neuronal morphology and synaptic connectivity. Tactile stimulation is a positive early experience that mimics maternal licking and grooming in the rat. Exposing rat pups to this positive experience can be completed easily and cost-effectively by using highly accessible materials such as a household duster. Using a cross-litter design, pups are either stroked or left undisturbed, for 15 min, three times per day throughout the perinatal period. To measure the neuroplastic changes related to this positive early experience, Golgi-Cox staining of brain tissue is utilized. Owing to the fact that Golgi-Cox impregnation stains a discrete number of neurons rather than all of the cells, staining of the rodent brain with Golgi-Cox solution permits the visualization of entire neuronal elements, including the cell body, dendrites, axons, and dendritic spines. The staining procedure is carried out over several days and requires that the researcher pay close attention to detail. However, once staining is completed, the entire brain has been impregnated and can be preserved indefinitely for ongoing analysis. Therefore, Golgi-Cox staining is a valuable resource for studying experience-dependent plasticity. PMID:24121525

SVAS3: Strain Vector Aided Sensorization of Soft Structures.

PubMed

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

2014-07-17

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

High-Performance Wireless Ammonia Gas Sensors Based on Reduced Graphene Oxide and Nano-Silver Ink Hybrid Material Loaded on a Patch Antenna.

PubMed

Wu, Bian; Zhang, Xingfei; Huang, Beiju; Zhao, Yutong; Cheng, Chuantong; Chen, Hongda

2017-09-09

Reduced graphene oxide (rGO) has been studied as a resistive ammonia gas sensor at room temperature. The sensitive hybrid material composed of rGO and nano-silver ink (Ag-ink) was loaded on a microstrip patch antenna to realize high-performance wireless ammonia sensors. The material was investigated using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Firstly, interdigital electrodes (IDEs) printed on the polyethylene terephthalate (PET) by direct printing were employed to measure the variation of resistance of the sensitive material with the ammonia concentration. The results indicated the response of sensor varied from 4.25% to 14.7% under 15-200 ppm ammonia concentrations. Furthermore, the hybrid material was loaded on a microstrip patch antenna fabricated by a conventional printed circuit board (PCB) process, and a 10 MHz frequency shift of the sensor antenna could be observed for 200 ppm ammonia gas. Finally, the wireless sensing property of the sensor antenna was successfully tested using the same emitted antenna outside the gas chamber with a high gain of 5.48 dBi, and an increased reflection magnitude of the emitted antenna due to the frequency mismatch of the sensor antenna was observed. Therefore, wireless ammonia gas sensors loaded on a patch antenna have significant application prospects in the field of Internet of Things (IoTs).

High-Performance Wireless Ammonia Gas Sensors Based on Reduced Graphene Oxide and Nano-Silver Ink Hybrid Material Loaded on a Patch Antenna

PubMed Central

Zhang, Xingfei; Huang, Beiju; Zhao, Yutong; Cheng, Chuantong; Chen, Hongda

2017-01-01

Reduced graphene oxide (rGO) has been studied as a resistive ammonia gas sensor at room temperature. The sensitive hybrid material composed of rGO and nano-silver ink (Ag-ink) was loaded on a microstrip patch antenna to realize high-performance wireless ammonia sensors. The material was investigated using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Firstly, interdigital electrodes (IDEs) printed on the polyethylene terephthalate (PET) by direct printing were employed to measure the variation of resistance of the sensitive material with the ammonia concentration. The results indicated the response of sensor varied from 4.25% to 14.7% under 15–200 ppm ammonia concentrations. Furthermore, the hybrid material was loaded on a microstrip patch antenna fabricated by a conventional printed circuit board (PCB) process, and a 10 MHz frequency shift of the sensor antenna could be observed for 200 ppm ammonia gas. Finally, the wireless sensing property of the sensor antenna was successfully tested using the same emitted antenna outside the gas chamber with a high gain of 5.48 dBi, and an increased reflection magnitude of the emitted antenna due to the frequency mismatch of the sensor antenna was observed. Therefore, wireless ammonia gas sensors loaded on a patch antenna have significant application prospects in the field of Internet of Things (IoTs). PMID:28891928

Optical fiber sensors for materials and structures characterization

NASA Technical Reports Server (NTRS)

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

1991-01-01

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

Material approaches to stretchable strain sensors.

PubMed

Park, Jaeyoon; You, Insang; Shin, Sangbaie; Jeong, Unyong

2015-04-27

With the recent progress made in wearable electronics, devices now require high flexibility and stretchability up to large strain levels (typically larger than 30 % strain). Wearable strain sensors or deformable strain sensors have been gaining increasing research interest because of the rapid development of electronic skins and robotics and because of their biomedical applications. Conventional brittle strain sensors made of metals and piezoresistors are not applicable for such stretchable sensors. This Review summarizes recent advances in stretchable sensors and focuses on material aspects for high stretchability and sensitivity. It begins with a brief introduction to the Wheatstone bridge circuit of conventional resistive strain sensors. Then, studies on the manipulation of materials are reviewed, including waved structural approaches for making metals and semiconductors stretchable, the use of liquid metals, and conductive filler/elastomer composites by using percolation among the fillers. For capacitive strain sensors, the constant conductivity of the electrode is a key factor in obtaining reliable sensors. Possible approaches to developing capacitive strain sensors are presented. This Review concludes with a discussion on the major challenges and perspectives related to stretchable strain sensors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

3,4-Diaminotoluene sensor development based on hydrothermally prepared MnCoxOy nanoparticles.

PubMed

Rahman, Mohammed M; Alam, M M; Asiri, Abdullah M; Islam, M A

2018-01-01

A facile hydrothermal process was used to prepare MnCo x O y nanoparticles (NPs) in alkaline medium (pH~10.5) at room temperature. The NPs were characterized by Fourier-transform infrared spectroscopy (FTIR), ultraviolet visible spectroscopy (UV/vis), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), and powder X-ray diffraction (XRD). A thin layer of NPs film as a chemical sensor was fabricated on a glassy carbon electrode (GCE) with the help of a conducting binder. The sensor was implemented successfully for the detection 3,4-DAT with reliable I-V approach at low potential. The sensor-features include good sensitivity (0.37 mAµmolL -1 cm -2 ), low detection limit (LOD=0.26±0.01 pmolL -1 at a signal to noise ratio of 3), low limit of quantification (LOQ=7.80±0.01 pmolL -1 ), good reliability, good reproducibility, ease of integration, and long-term stability were investigated. The sensor response towards 3,4-DAT is linear in logarithmic scale over a large concentration range (1.0 pmolL -1 to 1.0 µmolL -1 ). This work is introduced a route for future sensitive sensor development based on MnCo x O y NPs by reliable I-V method for the detection of hazardous and carcinogenic toxins in environmental and health care fields. Copyright © 2017 Elsevier B.V. All rights reserved.

An Insertable Passive LC Pressure Sensor Based on an Alumina Ceramic for In Situ Pressure Sensing in High-Temperature Environments.

PubMed

Xiong, Jijun; Li, Chen; Jia, Pinggang; Chen, Xiaoyong; Zhang, Wendong; Liu, Jun; Xue, Chenyang; Tan, Qiulin

2015-08-31

Pressure measurements in high-temperature applications, including compressors, turbines, and others, have become increasingly critical. This paper proposes an implantable passive LC pressure sensor based on an alumina ceramic material for in situ pressure sensing in high-temperature environments. The inductance and capacitance elements of the sensor were designed independently and separated by a thermally insulating material, which is conducive to reducing the influence of the temperature on the inductance element and improving the quality factor of the sensor. In addition, the sensor was fabricated using thick film integrated technology from high-temperature materials that ensure stable operation of the sensor in high-temperature environments. Experimental results showed that the sensor accurately monitored pressures from 0 bar to 2 bar at temperatures up to 800 °C. The sensitivity, linearity, repeatability error, and hysteretic error of the sensor were 0.225 MHz/bar, 95.3%, 5.5%, and 6.2%, respectively.

An Insertable Passive LC Pressure Sensor Based on an Alumina Ceramic for In Situ Pressure Sensing in High-Temperature Environments

PubMed Central

Xiong, Jijun; Li, Chen; Jia, Pinggang; Chen, Xiaoyong; Zhang, Wendong; Liu, Jun; Xue, Chenyang; Tan, Qiulin

2015-01-01

Pressure measurements in high-temperature applications, including compressors, turbines, and others, have become increasingly critical. This paper proposes an implantable passive LC pressure sensor based on an alumina ceramic material for in situ pressure sensing in high-temperature environments. The inductance and capacitance elements of the sensor were designed independently and separated by a thermally insulating material, which is conducive to reducing the influence of the temperature on the inductance element and improving the quality factor of the sensor. In addition, the sensor was fabricated using thick film integrated technology from high-temperature materials that ensure stable operation of the sensor in high-temperature environments. Experimental results showed that the sensor accurately monitored pressures from 0 bar to 2 bar at temperatures up to 800 °C. The sensitivity, linearity, repeatability error, and hysteretic error of the sensor were 0.225 MHz/bar, 95.3%, 5.5%, and 6.2%, respectively. PMID:26334279

Antioxidative effects of cinnamomi cortex: A potential role of iNOS and COX-II

PubMed Central

Chung, Jin-Won; Kim, Jeong-Jun; Kim, Sung-Jin

2011-01-01

Background: Cinnamomi cortex has wide varieties of pharmacological actions such as anti-inflammatory action, anti-platelet aggregation, and improving blood circulation. In this study, we tested to determine whether the Cinnamomi cortex extract has antioxidant activities. Materials and Methods: Antioxidative actions were explored by measuring free radical scavenging activity, NO levels, and reducing power. The mechanism of antioxidative action of Cinnamomi cortex was determined by measuring iNOS and COX-II expression in lipopolysaccharide (LPS) stimulated Raw cells. Results: Seventy percent methanolic extract of Cinnamomi cortex exerted significant 1,1-diphenyl--2--picrylhydrazyl (DPPH) free radicals and NO scavenging activities in a dose-dependent manner. More strikingly, the Cinnamomi cortex extract exerted dramatic reducing power activity (13-fold over control). Production of iNOS induced by LPS was significantly inhibited by the Cinnamomi cortex extract, suggesting that it inhibits NO production by suppressing iNOS expression. Additionally, COX-2 induced by LPS was dramatically inhibited by the Cinnamomi cortex extract. Conclusion: These results suggest that 70% methanolic extract of Cinnamomi cortex exerts significant antioxidant activity via inhibiting iNOS and COX-II induction. PMID:22262934

A state-of-the-art assessment of active structures

NASA Technical Reports Server (NTRS)

1992-01-01

A state-of-the-art assessment of active structures with emphasis towards the applications in aeronautics and space is presented. It is felt that since this technology area is growing at such a rapid pace in many different disciplines, it is not feasible to cover all of the current research but only the relevant work as relates to aeronautics and space. Research in smart actuation materials, smart sensors, and control of smart/intelligent structures is covered. In smart actuation materials, piezoelectric, magnetostrictive, shape memory, electrorheological, and electrostrictive materials are covered. For sensory materials, fiber optics, dielectric loss, and piezoelectric sensors are examined. Applications of embedded sensors and smart sensors are discussed.

Sensor Functionality of Conducting Polyaniline-Metal Oxide (TiO2/SnO2) Hybrid Materials Films toward Benzene and Toluene Vapors at Room Temperature

NASA Astrophysics Data System (ADS)

Subramanian, E.; Santhanamari, P.; Murugan, C.

2018-05-01

Polyaniline-metal oxide (TiO2/SnO2) organic-inorganic hybrid materials films were fabricated in situ on a printed circuit board (PCB) via drop coating technique. The mixture of aniline and metal oxide (TiO2/SnO2) dispersed in ethanol was applied along with an oxidant for the coating process. The formed material films were characterized by Fourier transform infra-red spectroscopy, x-ray diffraction and scanning electron microscopy techniques. The sensor functionality of the prepared films on PCB was investigated individually for the detection of benzene or toluene vapor at room temperature. The promptness of sensor response to analyte vapor and its recovery to air, as well as the concentration-dependent sensor functionality of the hybrid material films were investigated. The film form of hybrid materials has shown much improved sensor efficiency even at ambient air condition compared to the pellet form of the polyaniline-SnO2 hybrid material reported earlier, which sensed the same analytes only in nitrogen atmosphere.

Health monitoring method for composite materials

DOEpatents

Watkins, Jr., Kenneth S.; Morris, Shelby J [Hampton, VA

2011-04-12

An in-situ method for monitoring the health of a composite component utilizes a condition sensor made of electrically conductive particles dispersed in a polymeric matrix. The sensor is bonded or otherwise formed on the matrix surface of the composite material. Age-related shrinkage of the sensor matrix results in a decrease in the resistivity of the condition sensor. Correlation of measured sensor resistivity with data from aged specimens allows indirect determination of mechanical damage and remaining age of the composite component.

Design of intelligent composites with life-cycle health management capabilities

NASA Astrophysics Data System (ADS)

Rosania, Colleen L.; Larrosa, Cecilia C.; Chang, Fu-Kuo

2015-03-01

Use of carbon fiber reinforced polymers (CFRPs) presents challenges because of their complex manufacturing processes and different damage mechanics in relation to legacy metal materials. New monitoring methods for manufacturing, quality verification, damage estimation, and prognosis are needed to use CFRPs safely and efficiently. This work evaluates the development of intelligent composite materials using integrated piezoelectric sensors to monitor the material during cure and throughout service life. These sensors are used to propagate ultrasonic waves through the structure for health monitoring. During manufacturing, data is collected at different stages during the cure cycle, detecting the changing material properties during cure and verifying quality and degree of cure. The same sensors can then be used with previously developed techniques to perform damage detection, such as impact detection and matrix crack density estimation. Real-time damage estimation can be combined with prognostic models to predict future propagation of damage in the material. In this work experimental results will be presented from composite coupons with embedded piezoelectric sensors. Cure monitoring and damage detection results derived from analysis of the ultrasonic sensor signal will be shown. Sensitive signal parameters to the different stimuli in both the time and frequency domains will be explored for this analysis. From these results, use of the same sensor networks from manufacturing throughout the life of the composite material will demonstrate the full life-cycle monitoring capability of these intelligent materials.

A new miniature hand-held solar-blind reagentless standoff chemical, biological, and explosives (CBE) sensor

NASA Astrophysics Data System (ADS)

Hug, W. F.; Reid, R. D.; Bhartia, R.; Lane, A. L.

2008-04-01

Improvised explosive devices (IEDs), vehicle-borne improvised explosive devices (VBIEDs), and suicide bombers are a major threat to many countries and their citizenry. The ability to detect trace levels of these threats with a miniature, hand-held, reagentless, standoff sensor represents a major improvement in the state of the art of CBE surface sensors. Photon Systems, Inc., in collaboration with Jet Propulsion Laboratory, recently demonstrated a new technology hand-held sensor for reagentless, close-range, standoff detection and identification of trace levels CBE materials on surfaces. This targeted ultraviolet CBE (TUCBE) sensor is the result of an Army Phase I STTR program. The resulting 5lb, 5W, flashlight-sized sensor can discriminate CBE from background materials using a combination of deep UV excited resonance Raman (RR) and laser induced native fluorescence (LINF) emissions resulting from excitation by a new technology deep UV laser. Detection and identification is accomplished in less than 1ms. Standoff excitation of suspicious packages, vehicles, persons, and other objects that may contain hazardous materials is accomplished using wavelengths below 250nm where Raman and native fluorescence emissions occupy distinctly different wavelength regions. This enables simultaneous detection of RR and LINF emissions with no interferences. The sensor employs fused RR/LINF chemometric methods to extract the identity of targeted materials from background clutter. Photon Systems has demonstrated detection and identification of 100ng/cm2 of explosives materials at a distance of 1 meter using a sensor with 3.8 cm optical aperture. Expansion of the optical aperture to 38 cm in a lantern-sized sensor will enable similar detection and identification of CBE materials at standoff distances of 10 meters. As a result of excitation and detection in the deep UV and the use of a gated detection system, the sensor is solar blind and can operate in full daylight conditions.

GREAT I. A Position Paper of the PPIWG (Public Participation and Information Work Group) Executive Board.

DTIC Science & Technology

1978-09-01

Jim C. Coxe Material Placement Arnold Vogel Misc. and various topics Edward Oldenburg Material placement Allen Varo Rip-rap needs Winona Port Authority...managemnt for all reeourcee. Should costs rais . to a level unacceptable to th the raer/conabsir the burden of proof to find ways to lower costs (i.e

MMP1, MMP9, and COX2 expressions in promonocytes are induced by breast cancer cells and correlate with collagen degradation, transformation-like morphological changes in MCF-10A acini, and tumor aggressiveness.

PubMed

Chimal-Ramírez, G K; Espinoza-Sánchez, N A; Utrera-Barillas, D; Benítez-Bribiesca, L; Velázquez, J R; Arriaga-Pizano, L A; Monroy-García, A; Reyes-Maldonado, E; Domínguez-López, M L; Piña-Sánchez, Patricia; Fuentes-Pananá, E M

2013-01-01

Tumor-associated immune cells often lack immune effector activities, and instead they present protumoral functions. To understand how tumors promote this immunological switch, invasive and noninvasive breast cancer cell (BRC) lines were cocultured with a promonocytic cell line in a Matrigel-based 3D system. We hypothesized that if communication exists between tumor and immune cells, coculturing would result in augmented expression of genes associated with tumor malignancy. Upregulation of proteases MMP1 and MMP9 and inflammatory COX2 genes was found likely in response to soluble factors. Interestingly, changes were more apparent in promonocytes and correlated with the aggressiveness of the BRC line. Increased gene expression was confirmed by collagen degradation assays and immunocytochemistry of prostaglandin 2, a product of COX2 activity. Untransformed MCF-10A cells were then used as a sensor of soluble factors with transformation-like capabilities, finding that acini formed in the presence of supernatants of the highly aggressive BRC/promonocyte cocultures often exhibited total loss of the normal architecture. These data support that tumor cells can modify immune cell gene expression and tumor aggressiveness may importantly reside in this capacity. Modeling interactions in the tumor stroma will allow the identification of genes useful as cancer prognostic markers and therapy targets.

A mobile ferromagnetic shape detection sensor using a Hall sensor array and magnetic imaging.

PubMed

Misron, Norhisam; Shin, Ng Wei; Shafie, Suhaidi; Marhaban, Mohd Hamiruce; Mailah, Nashiren Farzilah

2011-01-01

This paper presents a mobile Hall sensor array system for the shape detection of ferromagnetic materials that are embedded in walls or floors. The operation of the mobile Hall sensor array system is based on the principle of magnetic flux leakage to describe the shape of the ferromagnetic material. Two permanent magnets are used to generate the magnetic flux flow. The distribution of magnetic flux is perturbed as the ferromagnetic material is brought near the permanent magnets and the changes in magnetic flux distribution are detected by the 1-D array of the Hall sensor array setup. The process for magnetic imaging of the magnetic flux distribution is done by a signal processing unit before it displays the real time images using a netbook. A signal processing application software is developed for the 1-D Hall sensor array signal acquisition and processing to construct a 2-D array matrix. The processed 1-D Hall sensor array signals are later used to construct the magnetic image of ferromagnetic material based on the voltage signal and the magnetic flux distribution. The experimental results illustrate how the shape of specimens such as square, round and triangle shapes is determined through magnetic images based on the voltage signal and magnetic flux distribution of the specimen. In addition, the magnetic images of actual ferromagnetic objects are also illustrated to prove the functionality of mobile Hall sensor array system for actual shape detection. The results prove that the mobile Hall sensor array system is able to perform magnetic imaging in identifying various ferromagnetic materials.

A Mobile Ferromagnetic Shape Detection Sensor Using a Hall Sensor Array and Magnetic Imaging

PubMed Central

Misron, Norhisam; Shin, Ng Wei; Shafie, Suhaidi; Marhaban, Mohd Hamiruce; Mailah, Nashiren Farzilah

2011-01-01

This paper presents a Mobile Hall Sensor Array system for the shape detection of ferromagnetic materials that are embedded in walls or floors. The operation of the Mobile Hall Sensor Array system is based on the principle of magnetic flux leakage to describe the shape of the ferromagnetic material. Two permanent magnets are used to generate the magnetic flux flow. The distribution of magnetic flux is perturbed as the ferromagnetic material is brought near the permanent magnets and the changes in magnetic flux distribution are detected by the 1-D array of the Hall sensor array setup. The process for magnetic imaging of the magnetic flux distribution is done by a signal processing unit before it displays the real time images using a netbook. A signal processing application software is developed for the 1-D Hall sensor array signal acquisition and processing to construct a 2-D array matrix. The processed 1-D Hall sensor array signals are later used to construct the magnetic image of ferromagnetic material based on the voltage signal and the magnetic flux distribution. The experimental results illustrate how the shape of specimens such as square, round and triangle shapes is determined through magnetic images based on the voltage signal and magnetic flux distribution of the specimen. In addition, the magnetic images of actual ferromagnetic objects are also illustrated to prove the functionality of Mobile Hall Sensor Array system for actual shape detection. The results prove that the Mobile Hall Sensor Array system is able to perform magnetic imaging in identifying various ferromagnetic materials. PMID:22346653

Optical Fiber Grating Hydrogen Sensors: A Review

PubMed Central

Dai, Jixiang; Zhu, Li; Wang, Gaopeng; Xiang, Feng; Qin, Yuhuan; Wang, Min; Yang, Minghong

2017-01-01

In terms of hydrogen sensing and detection, optical fiber hydrogen sensors have been a research issue due to their intrinsic safety and good anti-electromagnetic interference. Among these sensors, hydrogen sensors consisting of fiber grating coated with sensitive materials have attracted intensive research interests due to their good reliability and distributed measurements. This review paper mainly focuses on optical fiber hydrogen sensors associated with fiber gratings and various materials. Their configurations and sensing performances proposed by different groups worldwide are reviewed, compared and discussed in this paper. Meanwhile, the challenges for fiber grating hydrogen sensors are also addressed. PMID:28287499

Optical Fiber Grating Hydrogen Sensors: A Review.

PubMed

Dai, Jixiang; Zhu, Li; Wang, Gaopeng; Xiang, Feng; Qin, Yuhuan; Wang, Min; Yang, Minghong

2017-03-12

In terms of hydrogen sensing and detection, optical fiber hydrogen sensors have been a research issue due to their intrinsic safety and good anti-electromagnetic interference. Among these sensors, hydrogen sensors consisting of fiber grating coated with sensitive materials have attracted intensive research interests due to their good reliability and distributed measurements. This review paper mainly focuses on optical fiber hydrogen sensors associated with fiber gratings and various materials. Their configurations and sensing performances proposed by different groups worldwide are reviewed, compared and discussed in this paper. Meanwhile, the challenges for fiber grating hydrogen sensors are also addressed.

Integrated optical tamper sensor with planar waveguide

DOEpatents

Carson, Richard F.; Casalnuovo, Stephen A.

1993-01-01

A monolithic optical tamper sensor, comprising an optical emitter and detector, connected by an optical waveguide and placed into the critical entry plane of an enclosed sensitive region, the tamper sensor having a myriad of scraps of a material optically absorbent at the wavelength of interest, such that when the absorbent material is in place on the waveguide, an unique optical signature can be recorded, but when entry is attempted into the enclosed sensitive region, the scraps of absorbent material will be displaced and the optical/electrical signature of the tamper sensor will change and that change can be recorded.

Integrated optical tamper sensor with planar waveguide

DOEpatents

Carson, R.F.; Casalnuovo, S.A.

1993-01-05

A monolithic optical tamper sensor, comprising an optical emitter and detector, connected by an optical waveguide and placed into the critical entry plane of an enclosed sensitive region, the tamper sensor having a myriad of scraps of a material optically absorbent at the wavelength of interest, such that when the absorbent material is in place on the waveguide, an unique optical signature can be recorded, but when entry is attempted into the enclosed sensitive region, the scraps of absorbent material will be displaced and the optical/electrical signature of the tamper sensor will change and that change can be recorded.

Electrochemical micro sensor

DOEpatents

Setter, Joseph R.; Maclay, G. Jordan

1989-09-12

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

Large-area graphene for sensor applications

NASA Astrophysics Data System (ADS)

Snow, Eric S.

2010-04-01

Graphene represents an important new material with potential Department of Defense sensor applications. At the Naval Research Laboratory we have developed three techniques to produce large-area graphene films. We have used this material to construct chemical and radio-frequency electromagnetic sensors. Here we report the initial results of this effort.

Solid State Gas Sensor Research in Germany – a Status Report

PubMed Central

Moos, Ralf; Sahner, Kathy; Fleischer, Maximilian; Guth, Ulrich; Barsan, Nicolae; Weimar, Udo

2009-01-01

This status report overviews activities of the German gas sensor research community. It highlights recent progress in the field of potentiometric, amperometric, conductometric, impedimetric, and field effect-based gas sensors. It is shown that besides step-by-step improvements of conventional principles, e.g. by the application of novel materials, novel principles turned out to enable new markets. In the field of mixed potential gas sensors, novel materials allow for selective detection of combustion exhaust components. The same goal can be reached by using zeolites for impedimetric gas sensors. Operando spectroscopy is a powerful tool to learn about the mechanisms in n-type and in p-type conductometric sensors and to design knowledge-based improved sensor devices. Novel deposition methods are applied to gain direct access to the material morphology as well as to obtain dense thick metal oxide films without high temperature steps. Since conductometric and impedimetric sensors have the disadvantage that a current has to pass the gas sensitive film, film morphology, electrode materials, and geometrical issues affect the sensor signal. Therefore, one tries to measure directly the Fermi level position either by measuring the gas-dependent Seebeck coefficient at high temperatures or at room temperature by applying a modified miniaturized Kelvin probe method, where surface adsorption-based work function changes drive the drain-source current of a field effect transistor. PMID:22408529

3D printing of highly elastic strain sensors using polyurethane/multiwall carbon nanotube composites

NASA Astrophysics Data System (ADS)

Christ, Josef F.; Hohimer, Cameron J.; Aliheidari, Nahal; Ameli, Amir; Mo, Changki; Pötschke, Petra

2017-04-01

As the desire for wearable electronics increases and the soft robotics industry advances, the need for novel sensing materials has also increased. Recently, there have been many attempts at producing novel materials, which exhibit piezoresistive behavior. However, one of the major shortcomings in strain sensing technologies is in the fabrication of such sensors. While there is significant research and literature covering the various methods for developing piezoresistive materials, fabricating complex sensor platforms is still a manufacturing challenge. Here, we report a facile method to fabricate multidirectional embedded strain sensors using additive manufacturing technology. Pure thermoplastic polyurethane (TPU) and TPU/multiwall carbon nanotubes (MWCNT) nanocomposites were 3D printed in tandem using a low-cost multi-material FDM printer to fabricate uniaxial and biaxial strain sensors with conductive paths embedded within the insulative TPU platform. The sensors were then subjected to a series of cyclic strain loads. The results revealed excellent piezoresistive responses of the sensors with cyclic repeatability in both the axial and transverse directions and in response to strains as high as 50%. Further, while strain-softening did occur in the embedded printed strain sensors, it was predictable and similar to the results found in the literature for bulk polymer nanocomposites. This works demonstrates the possibility of manufacturing embedded and multidirectional flexible strain sensors using an inexpensive and versatile method, with potential applications in soft robotics and flexible electronics and health monitoring.

Noise Modeling From Conductive Shields Using Kirchhoff Equations.

PubMed

Sandin, Henrik J; Volegov, Petr L; Espy, Michelle A; Matlashov, Andrei N; Savukov, Igor M; Schultz, Larry J

2010-10-09

Progress in the development of high-sensitivity magnetic-field measurements has stimulated interest in understanding the magnetic noise of conductive materials, especially of magnetic shields based on high-permeability materials and/or high-conductivity materials. For example, SQUIDs and atomic magnetometers have been used in many experiments with mu-metal shields, and additionally SQUID systems frequently have radio frequency shielding based on thin conductive materials. Typical existing approaches to modeling noise only work with simple shield and sensor geometries while common experimental setups today consist of multiple sensor systems with complex shield geometries. With complex sensor arrays used in, for example, MEG and Ultra Low Field MRI studies, knowledge of the noise correlation between sensors is as important as knowledge of the noise itself. This is crucial for incorporating efficient noise cancelation schemes for the system. We developed an approach that allows us to calculate the Johnson noise for arbitrary shaped shields and multiple sensor systems. The approach is efficient enough to be able to run on a single PC system and return results on a minute scale. With a multiple sensor system our approach calculates not only the noise for each sensor but also the noise correlation matrix between sensors. Here we will show how the algorithm can be implemented.

An investigation of interface transferring mechanism of surface-bonded fiber Bragg grating sensors

NASA Astrophysics Data System (ADS)

Wu, Rujun; Fu, Kunkun; Chen, Tian

2017-08-01

Surface-bonded fiber Bragg grating sensor has been widely used in measuring strain in materials. The existence of fiber Bragg grating sensor affects strain distribution of the host material, which may result in a decrease in strain measurement accuracy. To improve the measurement accuracy, a theoretical model of strain transfer from the host material to optical fiber was developed, incorporating the influence of the fiber Bragg grating sensor. Subsequently, theoretical predictions were validated by comparing with data from finite element analysis and the existing experiment [F. Ansari and Y. Libo, J. Eng. Mech. 124(4), 385-394 (1998)]. Finally, the effect of parameters of fiber Bragg grating sensors on the average strain transfer rate was discussed.

SVAS3: Strain Vector Aided Sensorization of Soft Structures

PubMed Central

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

2014-01-01

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

Remotely operable sample-taking appliance, especially for ascertaining radioactivity profiles in contaminated material surfaces

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

Hanulik, J.

1983-09-20

A sample-taking appliance comprises several sensors arranged on a turntable like sensor carrier in such a manner that the application areas of the small sensor sponges decrease stepwise from the first to the last sensor. By simple rotation of the turntable the sensors can be brought successively into a working position. The sensor carrier is preferably accommodated in a housing which is open at the bottom and which is raisable and lowerable in the frame of the appliance by, for example, a threaded spindle. The threaded spindle is driven by an electric motor. For each sampling the sensor carrier ismore » lowered until the cell voltage corresponds to a predetermined desired value. This produces sufficiently precise and reproductible measured values of the electrolytic current for ascertaining the removed layer thickness. The appliance makes it possible to take material samples even from locations of high radiation loading. The material layers removed as samples lie concentrically above each other so that the graduation of the application areas comes into full effect and the material samples taken by the small sponges and the radioactivity contained therein are not falsified.« less

Design and Development for Capacitive Humidity Sensor Applications of Lead-Free Ca,Mg,Fe,Ti-Oxides-Based Electro-Ceramics with Improved Sensing Properties via Physisorption

PubMed Central

Tripathy, Ashis; Pramanik, Sumit; Manna, Ayan; Bhuyan, Satyanarayan; Azrin Shah, Nabila Farhana; Radzi, Zamri; Abu Osman, Noor Azuan

2016-01-01

Despite the many attractive potential uses of ceramic materials as humidity sensors, some unavoidable drawbacks, including toxicity, poor biocompatibility, long response and recovery times, low sensitivity and high hysteresis have stymied the use of these materials in advanced applications. Therefore, in present investigation, we developed a capacitive humidity sensor using lead-free Ca,Mg,Fe,Ti-Oxide (CMFTO)-based electro-ceramics with perovskite structures synthesized by solid-state step-sintering. This technique helps maintain the submicron size porous morphology of the developed lead-free CMFTO electro-ceramics while providing enhanced water physisorption behaviour. In comparison with conventional capacitive humidity sensors, the presented CMFTO-based humidity sensor shows a high sensitivity of up to 3000% compared to other materials, even at lower signal frequency. The best also shows a rapid response (14.5 s) and recovery (34.27 s), and very low hysteresis (3.2%) in a 33%–95% relative humidity range which are much lower values than those of existing conventional sensors. Therefore, CMFTO nano-electro-ceramics appear to be very promising materials for fabricating high-performance capacitive humidity sensors. PMID:27455263

Humidity Sensors Printed on Recycled Paper and Cardboard

PubMed Central

Mraović, Matija; Muck, Tadeja; Pivar, Matej; Trontelj, Janez; Pleteršek, Anton

2014-01-01

Research, design, fabrication and results of various screen printed capacitive humidity sensors is presented in this paper. Two types of capacitive humidity sensors have been designed and fabricated via screen printing on recycled paper and cardboard, obtained from the regional paper and cardboard industry. As printing ink, commercially available silver nanoparticle-based conductive ink was used. A considerable amount of work has been devoted to the humidity measurement methods using paper as a dielectric material. Performances of different structures have been tested in a humidity chamber. Relative humidity in the chamber was varied in the range of 35%–80% relative humidity (RH) at a constant temperature of 23 °C. Parameters of interest were capacitance and conductance of each sensor material, as well as long term behaviour. Process reversibility has also been considered. The results obtained show a mainly logarithmic response of the paper sensors, with the only exception being cardboard-based sensors. Recycled paper-based sensors exhibit a change in value of three orders of magnitude, whereas cardboard-based sensors have a change in value of few 10s over the entire scope of relative humidity range (RH 35%–90%). Two different types of capacitor sensors have been investigated: lateral (comb) type sensors and modified, perforated flat plate type sensors. The objective of the present work was to identify the most important factors affecting the material performances with humidity, and to contribute to the development of a sensor system supported with a Radio Frequency Identification (RFID) chip directly on the material, for use in smart packaging applications. Therefore, the authors built a passive and a battery-supported wireless module based on SL900A smart sensory tag's IC to achieve UHF-RFID functionality with data logging capability. PMID:25072347

Effect of cobalt doping on the structural, magnetic and abnormal thermal expansion properties of NaZn13-type La(Fe1-xCox)11.4Al1.6 compounds.

PubMed

Zhao, Yuqiang; Huang, Rongjin; Li, Shaopeng; Wang, Wei; Jiang, Xingxing; Lin, Zheshuai; Li, Jiangtao; Li, Laifeng

2016-07-27

Cubic NaZn13-type La(Fe1-xCox)11.4Al1.6 compounds were synthesized and extensively explored through crystal structure and magnetization analyses. By optimizing the chemical composition, the isotropic abnormal properties of excellent zero and giant negative thermal expansion in a pure form were both found at different temperature ranges through room temperature. Moreover, the temperature regions with the remarkable abnormal thermal expansion (ATE) properties have been broadened which are controlled by the dM/dT. The present study demonstrates that the ATE behavior mainly depends on special structural and magnetic properties. These diverse properties suggest the high potential of La(Fe1-xCox)11.4Al1.6 for the development of abnormal expansion materials.

Au-Graphene Hybrid Plasmonic Nanostructure Sensor Based on Intensity Shift

PubMed Central

Alharbi, Raed; Irannejad, Mehrdad; Yavuz, Mustafa

2017-01-01

Integrating plasmonic materials, like gold with a two-dimensional material (e.g., graphene) enhances the light-material interaction and, hence, plasmonic properties of the metallic nanostructure. A localized surface plasmon resonance sensor is an effective platform for biomarker detection. They offer a better bulk surface (local) sensitivity than a regular surface plasmon resonance (SPR) sensor; however, they suffer from a lower figure of merit compared to that one in a propagating surface plasmon resonance sensors. In this work, a decorated multilayer graphene film with an Au nanostructures was proposed as a liquid sensor. The results showed a significant improvement in the figure of merit compared with other reported localized surface plasmon resonance sensors. The maximum figure of merit and intensity sensitivity of 240 and 55 RIU−1 (refractive index unit) at refractive index change of 0.001 were achieved which indicate the capability of the proposed sensor to detect a small change in concentration of liquids in the ng/mL level which is essential in early-stage cancer disease detection. PMID:28106850

MIS-based sensors with hydrogen selectivity

DOEpatents

Li,; Dongmei, [Boulder, CO; Medlin, J William [Boulder, CO; McDaniel, Anthony H [Livermore, CA; Bastasz, Robert J [Livermore, CA

2008-03-11

The invention provides hydrogen selective metal-insulator-semiconductor sensors which include a layer of hydrogen selective material. The hydrogen selective material can be polyimide layer having a thickness between 200 and 800 nm. Suitable polyimide materials include reaction products of benzophenone tetracarboxylic dianhydride 4,4-oxydianiline m-phenylene diamine and other structurally similar materials.

First principles investigations of Fe2CrSi Heusler alloys by substitution of Co at Fe site

NASA Astrophysics Data System (ADS)

Jain, Rakesh; Lakshmi, N.; Jain, Vivek Kumar; Chandra, Aarti R.

2018-04-01

Electronic structure and magnetic properties of Fe2-xCoxCrSi Heusler alloys have been investigated by varying Co concentration from x = 0 to 2. On increasing Co concentration, lattice constant and magnetic moment of Fe2-xCoxCrSi alloys increase. These alloys show true half metallic Ferromagnetic behavior with 100% spin polarization. Band gap of the alloys also increase from 0.54 eV to 0.85 eV on increasing Co concentration making these alloys promising materials for spintronics based device applications.

Fabrication and Evaluation of a Graphene Oxide-Based Capacitive Humidity Sensor.

PubMed

Feng, Jinfeng; Kang, Xiaoxu; Zuo, Qingyun; Yuan, Chao; Wang, Weijun; Zhao, Yuhang; Zhu, Limin; Lu, Hanwei; Chen, Juying

2016-03-01

In this study, a CMOS compatible capacitive humidity sensor structure was designed and fabricated on a 200 mm CMOS BEOL Line. A top Al interconnect layer was used as an electrode with a comb/serpent structure, and graphene oxide (GO) was used as sensing material. XRD analysis was done which shows that GO sensing material has a strong and sharp (002) peak at about 10.278°, whereas graphite has (002) peak at about 26°. Device level CV and IV curves were measured in mini-environments at different relative humidity (RH) level, and saturated salt solutions were used to build these mini-environments. To evaluate the potential value of GO material in humidity sensor applications, a prototype humidity sensor was designed and fabricated by integrating the sensor with a dedicated readout ASIC and display/calibration module. Measurements in different mini-environments show that the GO-based humidity sensor has higher sensitivity, faster recovery time and good linearity performance. Compared with a standard humidity sensor, the measured RH data of our prototype humidity sensor can match well that of the standard product.

Chemical Sensors Based on Metal Oxide Nanostructures

NASA Technical Reports Server (NTRS)

Hunter, Gary W.; Xu, Jennifer C.; Evans, Laura J.; VanderWal, Randy L.; Berger, Gordon M.; Kulis, Mike J.; Liu, Chung-Chiun

2006-01-01

This paper is an overview of sensor development based on metal oxide nanostructures. While nanostructures such as nanorods show significan t potential as enabling materials for chemical sensors, a number of s ignificant technical challenges remain. The major issues addressed in this work revolve around the ability to make workable sensors. This paper discusses efforts to address three technical barriers related t o the application of nanostructures into sensor systems: 1) Improving contact of the nanostructured materials with electrodes in a microse nsor structure; 2) Controling nanostructure crystallinity to allow co ntrol of the detection mechanism; and 3) Widening the range of gases that can be detected by using different nanostructured materials. It is concluded that while this work demonstrates useful tools for furt her development, these are just the beginning steps towards realizati on of repeatable, controlled sensor systems using oxide based nanostr uctures.

2D metal profile detector using a polymeric fiber optic sensor

NASA Astrophysics Data System (ADS)

Hua, Wei-Shu; Hooks, Joshua R.; Erwin, Nicholas A.; Wu, Wen-Jong; Wang, Wei-Chih

2012-04-01

As sensors become integrated in more applications, interest in magnetostrictive sensor technology has blossomed. Magnetostrictive materials have many advantages and useful applications in daily life, such as high efficient coupling between elastic and polymer material, large displacement, magnetic field sensors, micro actuator and motion motor, etc. The purpose of this paper is to develop a metal sensor which is capable of detecting different geometries and shapes of metal objects. The main configuration is using a Mach-Zehnder fiber-optic interferometer coated with magnetostrictive material. The metal detector system is a novel design of metal detector, easy to fabricate and capable of high sensitivity. In our design, metal detection is made possible by disrupting the magnetic flux density that encompasses the magnetostriction sensor. In this paper, experimental setups are described and metal sensing results are presented. The results of detecting complex metal's geometry and metal's mapping results are discussed.

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.

Radiation detection and situation management by distributed sensor networks

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

Jan, Frigo; Mielke, Angela; Cai, D Michael

Detection of radioactive materials in an urban environment usually requires large, portal-monitor-style radiation detectors. However, this may not be a practical solution in many transport scenarios. Alternatively, a distributed sensor network (DSN) could complement portal-style detection of radiological materials through the implementation of arrays of low cost, small heterogeneous sensors with the ability to detect the presence of radioactive materials in a moving vehicle over a specific region. In this paper, we report on the use of a heterogeneous, wireless, distributed sensor network for traffic monitoring in a field demonstration. Through wireless communications, the energy spectra from different radiation detectorsmore » are combined to improve the detection confidence. In addition, the DSN exploits other sensor technologies and algorithms to provide additional information about the vehicle, such as its speed, location, class (e.g. car, truck), and license plate number. The sensors are in-situ and data is processed in real-time at each node. Relevant information from each node is sent to a base station computer which is used to assess the movement of radioactive materials.« less

Wireless sensor

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

Lamberti, Vincent E.; Howell, JR, Layton N.; Mee, David K.

Disclosed is a sensor for detecting a target material. The sensor includes a ferromagnetic metal and a molecular recognition reagent coupled to the ferromagnetic metal. The molecular recognition reagent is operable to expand upon exposure to vapor or liquid from the target material such that the molecular recognition reagent changes a tensile stress upon the ferromagnetic metal. The target material is detected based on changes in the magnetic switching characteristics of the ferromagnetic metal caused by the changes in the tensile stress.

Protective effect of Clerodendrum colebrookianum Walp., on acute and chronic inflammation in rats

PubMed Central

Deb, Lokesh; Dey, Amitabha; Sakthivel, G.; Bhattamishra, Subrat Kumar; Dutta, Amitsankar

2013-01-01

Aim: To evaluate antioxidant, anti-inflammatory potential of the aqueous extracts and its aqueous, n-butanol, ethyl-acetate, and chloroform fractions of Clerodendrum colebrookianum Walp. leaves. Materials and Methods: In this present study, all the test samples were evaluated on in-vivo inflammatory model such as carrageenan and histamine-induced acute-inflammation and cotton pellet induced granuloma formation in albino male rats. Test samples were also employed in in-vitro assays like DPPH* free radical scavenging activity and COX inhibition assay. Results: The test samples at the dose of 200mg/kg/p.o. were found to cause significant inhibition of carrageenan and histamine-induced inflammation and cotton pallet-induced granuloma formation on acute and chronic inflammation in rats. The test samples, except n-butanol fraction, exhibited inhibitory effect for both COX-1 and COX-2, in in-vitro assay but their percentage of inhibition values differs from each other. The test samples (aqueous extracts, aqueous, n-butanol, ethyl-acetate, and chloroform fractions) at 100 μg concentration exhibits 54.37%, 33.88%, 62.85%, 56.28%, and 57.48% DPPH* radical-scavenging effect respectively in in-vitro antioxidant study. Conclusion: These observations established the anti-inflammatory effect of C. colebrookianum leaves in acute and chronic stages of inflammation by free radical scavenging and inhibition of COX-1 and COX-2. PMID:24014914

Silicon carbide novel optical sensor for combustion systems and nuclear reactors

NASA Astrophysics Data System (ADS)

Lim, Geunsik; Kar, Aravinda

2014-09-01

Crystalline silicon carbide is a wide bandgap semiconductor material with excellent optical properties, chemical inertness, radiation hardness and high mechanical strength at high temperatures. It is an excellent material platform for sensor applications in harsh environments such as combustion systems and nuclear reactors. A laser doping technique is used to fabricate SiC sensors for different combustion gases such as CO2, CO, NO and NO2. The sensor operates based on the principle of semiconductor optics, producing optical signal in contrast to conventional electrical sensors that produces electrical signal. The sensor response is measured with a low power He-Ne or diode laser.

Disposable chemical sensors and biosensors made on cellulose paper.

PubMed

Kim, Joo-Hyung; Mun, Seongcheol; Ko, Hyun-U; Yun, Gyu-Young; Kim, Jaehwan

2014-03-07

Most sensors are based on ceramic or semiconducting substrates, which have no flexibility or biocompatibility. Polymer-based sensors have been the subject of much attention due to their ability to collect molecules on their sensing surface with flexibility. Beyond polymer-based sensors, the recent discovery of cellulose as a smart material paved the way to the use of cellulose paper as a potential candidate for mechanical as well as electronic applications such as actuators and sensors. Several different paper-based sensors have been investigated and suggested. In this paper, we review the potential of cellulose materials for paper-based application devices, and suggest their feasibility for chemical and biosensor applications.

Material Damage System and Method for Determining Same

NASA Technical Reports Server (NTRS)

Okojie, Robert (Inventor)

2017-01-01

A system and method for determining a change in a thickness and temperature of a surface of a material are disclosed herein. The system and the method are usable in a thermal protection system of a space vehicle, such as an aeroshell of a space vehicle. The system and method may incorporate micro electric sensors arranged in a ladder network and capacitor strip sensors. Corrosion or ablation causes a change in an electrical property of the sensors. An amount of or rate of the corrosion or the ablation and a temperature of the material is determined based on the change of the electrical property of the sensors.

Laser-induced forward transfer of single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Palla-Papavlu, A.; Dinescu, M.; Wokaun, A.; Lippert, T.

2014-10-01

The objective of this work is the application of laser-induced forward transfer (LIFT) for the fabrication of chemiresistor sensors. The receiver substrate is an array with metal electrodes and the active materials placed by LIFT are single-walled carbon nanotubes (SWCNT). The functionality of such sensors depends on the geometry of the active material onto the metallic electrodes. First the best geometry for the sensing materials and electrodes was determined, including the optimization of the process parameters for printing uniform pixels of SWCNT onto the sensor electrodes. The sensors were characterized in terms of their sensing characteristics, i.e., upon exposure to ammonia, proving the feasibility of LIFT.

Optical based tactile shear and normal load sensor

DOEpatents

Salisbury, Curt Michael

2015-06-09

Various technologies described herein pertain to a tactile sensor that senses normal load and/or shear load. The tactile sensor includes a first layer and an optically transparent layer bonded together. At least a portion of the first layer is made of optically reflective material. The optically transparent layer is made of resilient material (e.g., clear silicone rubber). The tactile sensor includes light emitter/light detector pair(s), which respectively detect either normal load or shear load. Light emitter(s) emit light that traverses through the optically transparent layer and reflects off optically reflective material of the first layer, and light detector(s) detect and measure intensity of reflected light. When a normal load is applied, the optically transparent layer compresses, causing a change in reflected light intensity. When shear load is applied, a boundary between optically reflective material and optically absorptive material is laterally displaced, causing a change in reflected light intensity.

Chemical sensors based on surface charge transfer

NASA Astrophysics Data System (ADS)

Mohtasebi, Amirmasoud; Kruse, Peter

2018-02-01

The focus of this review is an introduction to chemiresistive chemical sensors. The general concept of chemical sensors is briefly introduced, followed by different architectures of chemiresistive sensors and relevant materials. For several of the most common systems, the fabrication of the active materials used in such sensors and their properties are discussed. Furthermore, the sensing mechanism, advantages, and limitations of each group of chemiresistive sensors are briefly elaborated. Compared to electrochemical sensors, chemiresistive sensors have the key advantage of a simpler geometry, eliminating the need for a reference electrode. The performance of bulk chemiresistors can be improved upon by using freestanding ultra-thin films (nanomaterials) or field effect geometries. Both of those concepts have also been combined in a gateless geometry, where charge transport though a percolation network of nanomaterials is modulated via adsorbate doping.

Detection of VX Simulants Using Piezoresistive Microcantilever Sensors

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

Porter, Timothy L.; Venedam, Richard J.; Kyle, Kyle

2011-05-28

Piezoresistive microcantilever sensors may be used in a variety of sensing applications, including chemical analytes and some types of biological species. These sensors employ a tiny piezoresistive microcantilever functionalized with a “sensing material” that acts as a probe for the desired analyte. In this study, the microcantilever was partially embedded into the sensing material, producing a sensor element that is highly rigid and resistant to shock, making it suitable for portable or handheld operation. The sensing material matrix used was Hypol, a hydrogel capable of preserving the bio-functionality of molecules embedded into it. This matrix was combined with acetylcholinesterase tomore » form the finished sensing material. Results of exposing these sensors to a VX simulant, malathion, are presented for both vapor and liquid environments.« less

Active vibration damping using smart material

NASA Technical Reports Server (NTRS)

Baras, John S.; Yan, Zhuang

1994-01-01

We consider the modeling and active damping of an elastic beam using distributed actuators and sensors. The piezoelectric ceramic material (PZT) is used to build the actuator. The sensor is made of the piezoelectric polymer polyvinylidene fluoride (PVDF). These materials are glued on both sides of the beam. For the simple clamped beam, the closed loop controller has been shown to be able to extract energy from the beam. The shape of the actuator and its influence on the closed loop system performance are discussed. It is shown that it is possible to suppress the selected mode by choosing the appropriate actuator layout. It is also shown that by properly installing the sensor and determining the sensor shape we can further extract and manipulate the sensor signal for our control need.

Fiber Bragg gratings for civil engineering applications

NASA Astrophysics Data System (ADS)

Maher, Mohamed H.; Tabrizi, Khosrow; Prohaska, John D.; Snitzer, Elias

1996-04-01

Fiber Bragg gratings sensors offer a unique opportunity in civil engineering. They can be configured as a low noise distributed sensor network for measuring mechanical deformations and temperature. They are ideally suited for strain measurements of high modulus structural materials such as steel and concrete. There is considerable interest in the use of these sensors for infrastructural nondestructive testing and there have been several papers on the subject. We present some results of our experiments with fiber Bragg sensors as applied to structural engineering. These include the use of fiber gratings to measure strain behavior of steel, reinforced concrete, and some preliminary results on bituminous materials, such as asphalt concrete. In nondestructive testing using fiber Bragg gratings of structural materials the packaging of the sensors is important and is discussed.

Methods of use for sensor based fluid detection devices

NASA Technical Reports Server (NTRS)

Lewis, Nathan S. (Inventor)

2001-01-01

Methods of use and devices for detecting analyte in fluid. A system for detecting an analyte in a fluid is described comprising a substrate having a sensor comprising a first organic material and a second organic material where the sensor has a response to permeation by an analyte. A detector is operatively associated with the sensor. Further, a fluid delivery appliance is operatively associated with the sensor. The sensor device has information storage and processing equipment, which is operably connected with the device. This device compares a response from the detector with a stored ideal response to detect the presence of analyte. An integrated system for detecting an analyte in a fluid is also described where the sensing device, detector, information storage and processing device, and fluid delivery device are incorporated in a substrate. Methods for use for the above system are also described where the first organic material and a second organic material are sensed and the analyte is detected with a detector operatively associated with the sensor. The method provides for a device, which delivers fluid to the sensor and measures the response of the sensor with the detector. Further, the response is compared to a stored ideal response for the analyte to determine the presence of the analyte. In different embodiments, the fluid measured may be a gaseous fluid, a liquid, or a fluid extracted from a solid. Methods of fluid delivery for each embodiment are accordingly provided.

Improving the durability of the optical fiber sensor based on strain transfer analysis

NASA Astrophysics Data System (ADS)

Wang, Huaping; Jiang, Lizhong; Xiang, Ping

2018-05-01

To realize the reliable and long-term strain detection, the durability of optical fiber sensors has attracted more and more attention. The packaging technique has been considered as an effective method, which can enhance the survival ratios of optical fiber sensors to resist the harsh construction and service environment in civil engineering. To monitor the internal strain of structures, the embedded installation is adopted. Due to the different material properties between host material and the protective layer, the monitored structure embedded with sensors can be regarded as a typical model containing inclusions. Interfacial characteristic between the sensor and host material exists obviously, and the contacted interface is prone to debonding failure induced by the large interfacial shear stress. To recognize the local interfacial debonding damage and extend the effective life cycle of the embedded sensor, strain transfer analysis of a general three-layered sensing model is conducted to investigate the failure mechanism. The perturbation of the embedded sensor on the local strain field of host material is discussed. Based on the theoretical analysis, the distribution of the interfacial shear stress along the sensing length is characterized and adopted for the diagnosis of local interfacial debonding, and the sensitive parameters influencing the interfacial shear stress are also investigated. The research in this paper explores the interfacial debonding failure mechanism of embedded sensors based on the strain transfer analysis and provides theoretical basis for enhancing the interfacial bonding properties and improving the durability of embedded optical fiber sensors.

Hairlike Percutaneous Photochemical Sensors

NASA Technical Reports Server (NTRS)

George, Thomas; Loeb, Gerald

2004-01-01

Instrumentation systems based on hairlike fiber-optic photochemical sensors have been proposed as minimally invasive means of detecting biochemicals associated with cancer and other diseases. The fiber-optic sensors could be mass-produced as inexpensive, disposable components. The sensory tip of a fiber-optic sensor would be injected through the patient's skin into subcutaneous tissue. A biosensing material on the sensory tip would bind or otherwise react with the biochemical(s) of interest [the analyte(s)] to produce a change in optical properties that would be measured by use of an external photonic analyzer. After use, a fiber-optic sensor could be simply removed by plucking it out with tweezers. A fiber-optic sensor according to the proposal would be of the approximate size and shape of a human hair, and its sensory tip would resemble a follicle. Once inserted into a patient's subcutaneous tissue, the sensor would even more closely resemble a hair growing from a follicle (see Figure 1). The biosensing material on the sensory tip could consist of a chemical and/or cells cultured and modified for the purpose. The biosensing material would be contained within a membrane that would cover the tip. If the membrane were not permeable by an analyte, then it would be necessary to create pores in the membrane that would be large enough to allow analyte molecules to diffuse to the biosensing material, but not so large as to allow cells (if present as part of the biosensing material) to diffuse out. The end of the fiber-optic sensor opposite the sensory tip would be inserted in a fiberoptic socket in the photonic analyzer.

Specifically and wash-free labeling of SNAP-tag fused proteins with a hybrid sensor to monitor local micro-viscosity.

PubMed

Wang, Chao; Song, Xinbo; Chen, Lingcheng; Xiao, Yi

2017-05-15

Viscosity, as one of the major factors of intracellular microenvironment, influences the function of proteins. To detect local micro-viscosity of a protein, it is a precondition to apply a viscosity sensor for specifically target to proteins. However, all the reported small-molecule probes are just suitable for sensing/imaging of macro-viscosity in biological fluids of entire cells or organelles. To this end, we developed a hybrid sensor BDP-V BG by connecting a viscosity-sensitive boron-dipyrromethene (BODIPY) molecular rotor (BDP-V) to O 6 -benzylguanine (BG) for specific detection of local micro-viscosity of SNAP-tag fused proteins. We measured and calculated the reaction efficiency between the sensor and SNAP-tag protein in vitro to confirm the high labeling specificity. We also found that the labeling reaction results in a 53-fold fluorescence enhancement for the rotor, which qualifies it as a wash-free sensor with ignorable background fluorescence. The high sensitivity of protein labeled sensor (BDP-V-SNAP) to the changes of local viscosity was evaluated by detecting the enhancement of fluorescence lifetimes. Further, with the sensor BDP-V BG, we achieved high specific labeling of cells expressing two SNAP-tag fused proteins (nuclear histone H2B and mitochondrial COX8A). Two-photon excited fluorescence lifetime imaging revealed that, the micro-viscosities nearby the SNAP-tag fused two proteins are distinct. The different changes of local micro-viscosity of SNAP-tag fused histone protein in apoptosis induced by three nucleus-targeted drugs were also characterized for the first time. Copyright © 2016 Elsevier B.V. All rights reserved.

Monolayer Cu2Si as a potential gas sensor for NOx and COx (x = 1, 2): A first-principles study

NASA Astrophysics Data System (ADS)

Zhu, Hao-Hao; Ye, Xiao-Juan; Liu, Chun-Sheng; Yan, Xiao-Hong

2018-02-01

Although the metal-decoration can enhance the sensing properties of two-dimensional (2D) materials, the cyclic utilization of materials is hindered by the clustering tendency of metal atoms. Furthermore, there exists a risk of explosion of combustible gases with the electrical measure. Based on first-principles calculations, we investigate the adsorption of various gas molecules (O2, NO, NO2, NH3, N2, CO, CH4 and CO2) on the 2D Cu-Si extended system (Cu2Si). The NOx molecules are chemisorbed on the Cu2Si monolayer, while other gas molecules (except CH4 and N2) are held by an interaction intermediating between the physisorbed and chemisorbed states. The strong hybridizations between N 2p and Si 3p (Cu 4p) orbitals lead to the large adsorption energies. Interestingly, the adsorption of NOx (1 μB) and CO2 (2 μB) can induce magnetic moments on the intrinsically nonmagnetic Cu2Si monolayer. The magnetic moment of NO-Cu2Si mainly arises from the molecule, while the magnetic moments for the NO2 and CO2 adsorption almost origin from the monolayer. In addition, an antiferromagnetic coupling is found in CO-Cu2Si. The changes in magnetization upon the gas adsorption may be detected sensitively and safely, suggesting the Cu2Si monolayer is potential for gas sensing.

Flexible Transparent Electronic Gas Sensors.

PubMed

Wang, Ting; Guo, Yunlong; Wan, Pengbo; Zhang, Han; Chen, Xiaodong; Sun, Xiaoming

2016-07-01

Flexible and transparent electronic gas sensors capable of real-time, sensitive, and selective analysis at room-temperature, have gained immense popularity in recent years for their potential to be integrated into various smart wearable electronics and display devices. Here, recent advances in flexible transparent sensors constructed from semiconducting oxides, carbon materials, conducting polymers, and their nanocomposites are presented. The sensing material selection, sensor device construction, and sensing mechanism of flexible transparent sensors are discussed in detail. The critical challenges and future development associated with flexible and transparent electronic gas sensors are presented. Smart wearable gas sensors are believed to have great potential in environmental monitoring and noninvasive health monitoring based on disease biomarkers in exhaled gas. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Advanced Sensor and Packaging Technologies for Intelligent Adaptive Engine Controls (Preprint)

DTIC Science & Technology

2013-05-01

combination of micro-electromechanical systems (MEMS) sensor technology, novel ceramic materials, high - temperature electronics, and advanced harsh...with simultaneous pressure measurements up to 1,000 psi. The combination of a high - temperature , high -pressure-ratio compressor system, and adaptive...combination of micro-electromechanical systems (MEMS) sensor technology, novel ceramic materials, high temperature electronics, and advanced harsh

Rutting Performance of Cold-Applied Asphalt Repair Materials for Airfield Pavements

DTIC Science & Technology

2017-06-23

susceptibility of hot mix asphalt (HMA) using the asphalt pavement analyzer (APA). Designation T340- 10. Washington, DC: American Association of State...ER D C/ G SL T R- 17 -1 0 Rutting Performance of Cold-Applied Asphalt Repair Materials for Airfield Pavements G eo te ch ni ca l a nd S...of Cold-Applied Asphalt Repair Materials for Airfield Pavements Ben C. Cox, John F. Rushing, and Web Floyd Geotechnical and Structures Laboratory

Fiber Bragg Grating Sensors toward Structural Health Monitoring in Composite Materials: Challenges and Solutions

PubMed Central

Kinet, Damien; Mégret, Patrice; Goossen, Keith W.; Qiu, Liang; Heider, Dirk; Caucheteur, Christophe

2014-01-01

Nowadays, smart composite materials embed miniaturized sensors for structural health monitoring (SHM) in order to mitigate the risk of failure due to an overload or to unwanted inhomogeneity resulting from the fabrication process. Optical fiber sensors, and more particularly fiber Bragg grating (FBG) sensors, outperform traditional sensor technologies, as they are lightweight, small in size and offer convenient multiplexing capabilities with remote operation. They have thus been extensively associated to composite materials to study their behavior for further SHM purposes. This paper reviews the main challenges arising from the use of FBGs in composite materials. The focus will be made on issues related to temperature-strain discrimination, demodulation of the amplitude spectrum during and after the curing process as well as connection between the embedded optical fibers and the surroundings. The main strategies developed in each of these three topics will be summarized and compared, demonstrating the large progress that has been made in this field in the past few years. PMID:24763215

Polaronic transport and thermoelectricity in Fe1 -xCoxSb2S4 (x =0 , 0.1, and 0.2)

NASA Astrophysics Data System (ADS)

Liu, Yu; Kang, Chang-Jong; Stavitski, Eli; Du, Qianheng; Attenkofer, Klaus; Kotliar, G.; Petrovic, C.

2018-04-01

We report a study of Co-doped berthierite Fe1 -xCoxSb2S4 (x =0 , 0.1, and 0.2). The alloy series of Fe1 -xCoxSb2S4 crystallize in an orthorhombic structure with the Pnma space group, similar to FeSb2, and show semiconducting behavior. The large discrepancy between activation energy for conductivity, Eρ (146 ˜270 meV ), and thermopower, ES (47 ˜108 meV ), indicates the polaronic transport mechanism. Bulk magnetization and heat-capacity measurements of pure FeSb2S4 (x =0 ) exhibit a broad antiferromagnetic transition (TN=46 K ) followed by an additional weak transition (T*=50 K ). Transition temperatures (TN and T*) slightly decrease with increasing Co content x . This is also reflected in the thermal conductivity measurement, indicating strong spin-lattice coupling. Fe1 -xCoxSb2S4 shows relatively high value of thermopower (up to ˜624 μ V K-1 at 300 K) and thermal conductivity much lower when compared to FeSb2, a feature desired for potential applications based on FeSb2 materials.

Material for magnetostrictive sensors and other applications based on ferrite materials

DOEpatents

McCallum, R. William; Snyder, John E.; Dennis, Kevin W.; Schwichtenberg, Carl R.; Jiles, David C.

2000-07-25

The present invention provides magnetostrictive compositions that include an oxide ferrite which provides mechanical properties that make the magnetostrictive compositions effective for use as sensors and actuators.

Electrospinning cellulose based nanofibers for sensor applications

NASA Astrophysics Data System (ADS)

Nartker, Steven

2009-12-01

Bacterial pathogens have recently become a serious threat to the food and water supply. A biosensor based on an electrochemical immunoassay has been developed for detecting food borne pathogens, such as Escherichia coli (E. coli) O157:H7. These sensors consist of several materials including, cellulose, cellulose nitrate, polyaniline and glass fibers. The current sensors have not been optimized in terms of microscale architecture and materials. The major problem associated with the current sensors is the limited concentration range of pathogens that provides a linear response on the concentration conductivity chart. Electrospinning is a process that can be used to create a patterned fiber mat design that will increase the linear range and lower the detection limit of these sensors by improving the microscale architecture. Using the electrospinning process to produce novel mats of cellulose nitrate will offer improved surface area, and the cellulose nitrate can be treated to further improve chemical interactions required for sensor activity. The macro and micro architecture of the sensor is critical to the performance of the sensors. Electrospinning technology can be used to create patterned architectures of nanofibers that will enhance sensor performance. To date electrospinning of cellulose nitrate has not been performed and optimization of the electrospinning process will provide novel materials suitable for applications such as filtration and sensing. The goal of this research is to identify and elucidate the primary materials and process factors necessary to produce cellulose nitrate nanofibers using the electrospinning process that will improve the performance of biosensors. Cellulose nitrate is readily dissolved in common organic solvents such as acetone, tetrahydrofuran (THF) and N,N dimethylformamide (DMF). These solvents can be mixed with other latent solvents such as ethanol and other alcohols to provide a solvent system with good electrospinning behavior. Using cellulose nitrate in biosensor materials provides excellent antibody binding characteristics that are resistant to pH changes. Sensors will be constructed of electrospun materials and compared to existing materials. The main advantage of electrospinning fiber mats is the increased surface area, and controllable morphology, which ultimately affects biosensor performance. Characterization tools will include Environmental Scanning Electron Microscopy (ESEM), BET N2 adsorption, X-Ray Photoelectron Spectroscopy (XPS), Dynamic Mechanical Analysis (DMA) and AC impedance.

Acoustic Emission Measurement with Fiber Bragg Gratings for Structure Health Monitoring

NASA Technical Reports Server (NTRS)

Banks, Curtis E.; Walker, James L.; Russell, Sam; Roth, Don; Mabry, Nehemiah; Wilson, Melissa

2010-01-01

Structural Health monitoring (SHM) is a way of detecting and assessing damage to large scale structures. Sensors used in SHM for aerospace structures provide real time data on new and propagating damage. One type of sensor that is typically used is an acoustic emission (AE) sensor that detects the acoustic emissions given off from a material cracking or breaking. The use of fiber Bragg grating (FBG) sensors to provide acoustic emission data for damage detection is studied. In this research, FBG sensors are used to detect acoustic emissions of a material during a tensile test. FBG sensors were placed as a strain sensor (oriented parallel to applied force) and as an AE sensor (oriented perpendicular to applied force). A traditional AE transducer was used to collect AE data to compare with the FBG data. Preliminary results show that AE with FBGs can be a viable alternative to traditional AE sensors.

Multi-sensor electrometer

NASA Technical Reports Server (NTRS)

Gompf, Raymond (Inventor); Buehler, Martin C. (Inventor)

2003-01-01

An array of triboelectric sensors is used for testing the electrostatic properties of a remote environment. The sensors may be mounted in the heel of a robot arm scoop. To determine the triboelectric properties of a planet surface, the robot arm scoop may be rubbed on the soil of the planet and the triboelectrically developed charge measured. By having an array of sensors, different insulating materials may be measured simultaneously. The insulating materials may be selected so their triboelectric properties cover a desired range. By mounting the sensor on a robot arm scoop, the measurements can be obtained during an unmanned mission.

Metformin inhibits inflammatory response via AMPK-PTEN pathway in vascular smooth muscle cells

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

Kim, Sun Ae; Choi, Hyoung Chul, E-mail: hcchoi@med.yu.ac.kr

2012-09-07

Highlights: Black-Right-Pointing-Pointer PTEN was induced by metformin and inhibited by compound C and AMPK siRNA. Black-Right-Pointing-Pointer Metformin suppressed TNF-{alpha}-induced COX-2 and iNOS mRNA expression. Black-Right-Pointing-Pointer Compound C and bpv (pic) increased iNOS and COX-2 protein expression. Black-Right-Pointing-Pointer NF-{kappa}B activation was restored by inhibiting AMPK and PTEN. Black-Right-Pointing-Pointer AMPK and PTEN regulated TNF-{alpha}-induced ROS production in VSMCs. -- Abstract: Atherosclerosis is a chronic inflammation of the coronary arteries. Vascular smooth muscle cells (VSMCs) stimulated by cytokines and chemokines accelerate the inflammatory response and migrate to the injured endothelium during the progression of atherosclerosis. Activation of AMP activated protein kinase (AMPK), amore » key sensor maintaining metabolic homeostasis, suppresses the inflammatory response. However, how AMPK regulates the inflammatory response is poorly understood. To identify the mechanism of this response, we focused on phosphatase and tensin homolog (PTEN), which is a negative regulator of inflammation. We investigated that activation of AMPK-induced PTEN expression and suppression of the inflammatory response through the AMPK-PTEN pathway in VSMCs. We treated with the well-known AMPK activator metformin to induce PTEN expression. PTEN was induced by metformin (2 mM) and inhibited by compound C (10 {mu}M) and AMPK siRNA. Tumor necrosis factor-alpha (TNF-{alpha}) was used to induce inflammation. The inflammatory response was confirmed by cyclooxygenase (COX)-2, inducible nitric oxide synthase (iNOS) expression, and activation of nuclear factor (NF)-{kappa}B. Metformin suppressed COX-2 and iNOS mRNA and protein expression dose dependently. Treatment with compound C and bpv (pic) in the presence of metformin, iNOS and COX-2 protein expression increased. NF-{kappa}B activation decreased in response to metformin and was restored by inhibiting AMPK and PTEN. Inhibiting AMPK and PTEN restored ROS levels stimulated with TNF-{alpha}. Taken together, PTEN could be a possible downstream regulator of AMPK, and the AMPK-PTEN pathway might be important in the regulation of the inflammatory response in VSMCs.« less

High-Temperature Piezoelectric Sensing

PubMed Central

Jiang, Xiaoning; Kim, Kyungrim; Zhang, Shujun; Johnson, Joseph; Salazar, Giovanni

2014-01-01

Piezoelectric sensing is of increasing interest for high-temperature applications in aerospace, automotive, power plants and material processing due to its low cost, compact sensor size and simple signal conditioning, in comparison with other high-temperature sensing techniques. This paper presented an overview of high-temperature piezoelectric sensing techniques. Firstly, different types of high-temperature piezoelectric single crystals, electrode materials, and their pros and cons are discussed. Secondly, recent work on high-temperature piezoelectric sensors including accelerometer, surface acoustic wave sensor, ultrasound transducer, acoustic emission sensor, gas sensor, and pressure sensor for temperatures up to 1,250 °C were reviewed. Finally, discussions of existing challenges and future work for high-temperature piezoelectric sensing are presented. PMID:24361928

Fiber optic sensors for corrosion detection

NASA Technical Reports Server (NTRS)

Smith, Alphonso C.

1993-01-01

The development of fiber optic sensors for the detection of a variety of material parameters has grown tremendously over the past several years. Additionally, the potential for analytical applications of fiber optic sensors have become more widely used. New pH sensors have also been developed using fiber optic techniques to detect fluorescence characteristics from immobilized fluorogenic reagent chemicals. The primary purpose of this research was to investigate the feasibility of using fiber optic sensors to detect the presence of Al(sup 3+) ions made in the process of environmental corrosion of aluminum materials. The Al(sup 3+) ions plus a variety of other type of metal ions can be detected using analytical techniques along with fiber optic sensors.

Distributed Stress Sensing and Non-Destructive Tests Using Mechanoluminescence Materials

NASA Astrophysics Data System (ADS)

Rahimi, Mohammad Reza

Rapid aging of infrastructure systems is currently pervasive in the US and the anticipated cost until 2020 for rehabilitation of aging lifeline will reach 3.6 trillion US dollars (ASCE 2013). Reliable condition or serviceability assessment is critically important in decision-making for economic and timely maintenance of the infrastructure systems. Advanced sensors and nondestructive test (NDT) methods are the key technologies for structural health monitoring (SHM) applications that can provide information on the current state of structures. There are many traditional sensors and NDT methods, for examples, strain gauges, ultrasound, radiography and other X-ray, etc. to detect any defect on the infrastructure. Considering that civil infrastructure is typically large-scale and exhibits complex behavior, estimation of structural conditions by the local sensing and NDT methods is a challenging task. Non-contact and distributed (or full-field) sensing and NDT method are desirable that can provide rich information on the civil infrastructure's state. Materials with the ability of emitting light, especially in the visible range, are named as luminescent materials. Mechanoluminescence (ML) phenomenon is the light emission from luminescent materials as a response of an induced mechanical stress. ML materials offer new opportunities for SHM that can directly visualize the stress and crack distributions on the surface of structures through ML light emission. Although material research for ML phenomena have been made substantially, applications of the ML sensors to full-field stress and crack visualization are still at infant stage and have yet to be full-fledged. Moreover, practical applications of the ML sensors for SHM of civil infrastructure have difficulties since numerous challenging problems (e.g. environmental effect) arise in actual applications. In order to realize a practical SHM system employing ML sensors, more research needs to be conducted, for examples, fundamental understandings of physics of ML phenomenon, method for quantitative stress measurements, calibration method for ML sensors, improvement of sensitivity, optimal manufacturing and design of ML sensors, environmental effects of ML phenomenon (e.g. temperature), image processing and analysis, etc. In this research, fundamental ML phenomena of two most promising ML sensing materials were experimentally studied and a methodology for full-field quantitative strain measurements, for the first time, was proposed along with a standardized calibration method. Characteristics and behavior of ML composites and thin films coated on the structure have been studied under various material tests including compression, tension, pure shear, bending, etc. In addition, ML emission sensitivity to the manufacturing parameters and experimental conditions was addressed in order to find optimal design the ML sensor. A phenomenological stress-optics transduction model for predicting the ML light intensity from a thin-film ML coating sensor subjected to in-plane stresses was proposed. A new full-field quantitative strain measuring methodology by ML thin film sensor was developed, for the first time, in order to visualize and measure the strain field. The results from the ML sensor were compared and verified by finite element simulation results. For NDT applications of ML sensors, experimental tests were conducted to visualize the cracks on structural surfaces and detect damages on structural components. In summary, this research proposes and realizes a new distributed stress sensor and NDT method using ML sensing materials. The proposed method is experimentally validated to be effective for stress measurement and crack visualizations. Successful completion of this research provides a leap toward a commercial light intensity-based optic sensor to be used as a new full-field stress measurement technology and NDT method.

Piezoelectric Actuator/Sensor Technology at Rockwell

NASA Technical Reports Server (NTRS)

Neurgaonkar, Ratnakar R.

1996-01-01

We describe the state-of-the art of piezoelectric materials based on perovskite and tungsten bronze families for sensor, actuator and smart structure applications. The microstructural defects in these materials have been eliminated to a large extent and the resulting materials exhibit exceedingly high performance for various applications. The performance of Rockwell actuators/sensors is at least 3 times better than commercially available products. These high performance actuators are being incorporated into various applications including, DOD, NASA and commercial. The multilayer actuator stacks fabricated from our piezoceramics are advantageous for sensing and high capacitance applications. In this presentation, we will describe the use of our high performance piezo-ceramics for actuators and sensors, including multilayer stacks and composite structures.

Material for magnetostrictive sensors and other applications based on ferrite materials

DOEpatents

McCallum, R. William; Snyder, John E.; Dennis, Kevin W.; Schwichtenberg, Carl R.; Jiles, David C.

2002-03-05

The present invention provides magnetostrictive composites that include an oxide ferrite and metallic binders which provides mechanical properties that make the magnetostrictive compositions effective for use as sensors and actuators.

Damage Detection Response Characteristics of Open Circuit Resonant (SansEC) Sensors

NASA Technical Reports Server (NTRS)

Dudley, Kenneth L.; Szatkowski, George N.; Smith, Laura J.; Koppen, Sandra V.; Ely, Jay J.; Nguyen, Truong X.; Wang, Chuantong; Ticatch, Larry A.; Mielnik, John J.

2013-01-01

The capability to assess the current or future state of the health of an aircraft to improve safety, availability, and reliability while reducing maintenance costs has been a continuous goal for decades. Many companies, commercial entities, and academic institutions have become interested in Integrated Vehicle Health Management (IVHM) and a growing effort of research into "smart" vehicle sensing systems has emerged. Methods to detect damage to aircraft materials and structures have historically relied on visual inspection during pre-flight or post-flight operations by flight and ground crews. More quantitative non-destructive investigations with various instruments and sensors have traditionally been performed when the aircraft is out of operational service during major scheduled maintenance. Through the use of reliable sensors coupled with data monitoring, data mining, and data analysis techniques, the health state of a vehicle can be detected in-situ. NASA Langley Research Center (LaRC) is developing a composite aircraft skin damage detection method and system based on open circuit SansEC (Sans Electric Connection) sensor technology. Composite materials are increasingly used in modern aircraft for reducing weight, improving fuel efficiency, and enhancing the overall design, performance, and manufacturability of airborne vehicles. Materials such as fiberglass reinforced composites (FRC) and carbon-fiber-reinforced polymers (CFRP) are being used to great advantage in airframes, wings, engine nacelles, turbine blades, fairings, fuselage structures, empennage structures, control surfaces and aircraft skins. SansEC sensor technology is a new technical framework for designing, powering, and interrogating sensors to detect various types of damage in composite materials. The source cause of the in-service damage (lightning strike, impact damage, material fatigue, etc.) to the aircraft composite is not relevant. The sensor will detect damage independent of the cause. Damage in composite material is generally associated with a localized change in material permittivity and/or conductivity. These changes are sensed using SansEC. The unique electrical signatures (amplitude, frequency, bandwidth, and phase) are used for damage detection and diagnosis. An operational system and method would incorporate a SansEC sensor array on select areas of the aircraft exterior surfaces to form a "Smart skin" sensing surface. In this paper a new method and system for aircraft in-situ damage detection and diagnosis is presented. Experimental test results on seeded fault damage coupons and computational modeling simulation results are presented. NASA LaRC has demonstrated with individual sensors that SansEC sensors can be effectively used for in-situ composite damage detection of delamination, voids, fractures, and rips. Keywords: Damage Detection, Composites, Integrated Vehicle Health Monitoring (IVHM), Aviation Safety, SansEC Sensors

Tuning the dynamic range and sensitivity of optical oxygen-sensors by employing differently substituted polystyrene-derivatives

PubMed Central

Koren, Klaus; Hutter, Lukas; Enko, Barbara; Pein, Andreas; Borisov, Sergey M.; Klimant, Ingo

2013-01-01

Ten different polystyrene-derivatives were tested with respect to their potential use as matrix materials for optical oxygen sensors in combination with the platinum(II) meso-tetra(4-fluorophenyl)tetrabenzoporphyrin as indicator dye. Either halogen atoms or bulky residues were introduced as substituents on the phenyl ring. A fine-tuning of the sensor sensitivity was achieved, without compromising solubility of the indicator in the matrix by providing a chemical environment very similar to polystyrene (PS), a standard matrix in optical oxygen sensors. To put the results into perspective, the studied materials were compared to PS regarding sensitivity of the sensor, molecular weight and glass-transition temperature. The materials promise to be viable alternatives to PS with respect to the requirements posed in various sensor application fields. Some of the polymers (e.g. poly(2,6-dichlorostyrene)) promise to be of use in applications requiring measurements from 0 to 100% oxygen due to linearity across this range. Poly(4-tert-butylstyrene) and poly(2,6-fluorostyrene), on the other hand, yield sensors with increased sensitivity. Sensor stability was evaluated as a function of the matrix, a topic which has not received a lot of interest so far. PMID:23576846

A wearable strain sensor based on a carbonized nano-sponge/silicone composite for human motion detection.

PubMed

Yu, Xiao-Guang; Li, Yuan-Qing; Zhu, Wei-Bin; Huang, Pei; Wang, Tong-Tong; Hu, Ning; Fu, Shao-Yun

2017-05-25

Melamine sponge, also known as nano-sponge, is widely used as an abrasive cleaner in our daily life. In this work, the fabrication of a wearable strain sensor for human motion detection is first demonstrated with a commercially available nano-sponge as a starting material. The key resistance sensitive material in the wearable strain sensor is obtained by the encapsulation of a carbonized nano-sponge (CNS) with silicone resin. The as-fabricated CNS/silicone sensor is highly sensitive to strain with a maximum gauge factor of 18.42. In addition, the CNS/silicone sensor exhibits a fast and reliable response to various cyclic loading within a strain range of 0-15% and a loading frequency range of 0.01-1 Hz. Finally, the CNS/silicone sensor as a wearable device for human motion detection including joint motion, eye blinking, blood pulse and breathing is demonstrated by attaching the sensor to the corresponding parts of the human body. In consideration of the simple fabrication technique, low material cost and excellent strain sensing performance, the CNS/silicone sensor is believed to have great potential in the next-generation of wearable devices for human motion detection.

Optochemical sensor based on screenprinted fluorescent sensorspots surrounded by organic photodiodes for multianalyte detection

NASA Astrophysics Data System (ADS)

Kraker, E.; Lamprecht, B.; Haase, A.; Jakopic, G.; Abel, T.; Konrad, C.; Köstler, S.; Tscherner, M.; Stadlober, B.; Mayr, T.

2010-08-01

A compact, integrated photoluminescence based oxygen sensor, utilizing an organic light emitting device (OLED) as the light source and an organic photodiode (OPD) as the detection unit, is described. The detection system of the sensor array consists of an array of circular screen-printed fluorescent sensor spots surrounded by organic photodiodes as integrated fluorescence detectors. The OPD originates from the well-known Tang photodiode, consisting of a stacked layer of copper phthalocyanine (CuPc, p-type material) and perylene tetracarboxylic bisbenzimidazole (PTCBi, n-type material). An additional layer of tris-8-hydroxyquinolinatoaluminium (Alq3, n-type material) was inserted between the PTCBi layer and cathode. An ORMOCERR layer was used as encapsulation layer. For excitation an organic light emitting diode is used. The sensor spot and the detector are processed on the same flexible substrate. This approach not only simplifies the detection system by minimizing the numbers of required optical components - no optical filters have to be used for separating the excitation light and the luminescent emission-, but also has a large potential for low-cost sensor applications. The feasibility of the concept is demonstrated by an integrated oxygen sensor, indicating good performance. Sensor schemes for other chemical parameters are proposed.

Study on Impact Acoustic—Visual Sensor-Based Sorting of ELV Plastic Materials

PubMed Central

Huang, Jiu; Tian, Chuyuan; Ren, Jingwei; Bian, Zhengfu

2017-01-01

This paper concentrates on a study of a novel multi-sensor aided method by using acoustic and visual sensors for detection, recognition and separation of End-of Life vehicles’ (ELVs) plastic materials, in order to optimize the recycling rate of automotive shredder residues (ASRs). Sensor-based sorting technologies have been utilized for material recycling for the last two decades. One of the problems still remaining results from black and dark dyed plastics which are very difficult to recognize using visual sensors. In this paper a new multi-sensor technology for black plastic recognition and sorting by using impact resonant acoustic emissions (AEs) and laser triangulation scanning was introduced. A pilot sorting system which consists of a 3-dimensional visual sensor and an acoustic sensor was also established; two kinds commonly used vehicle plastics, polypropylene (PP) and acrylonitrile-butadiene-styrene (ABS) and two kinds of modified vehicle plastics, polypropylene/ethylene-propylene-diene-monomer (PP-EPDM) and acrylonitrile-butadiene-styrene/polycarbonate (ABS-PC) were tested. In this study the geometrical features of tested plastic scraps were measured by the visual sensor, and their corresponding impact acoustic emission (AE) signals were acquired by the acoustic sensor. The signal processing and feature extraction of visual data as well as acoustic signals were realized by virtual instruments. Impact acoustic features were recognized by using FFT based power spectral density analysis. The results shows that the characteristics of the tested PP and ABS plastics were totally different, but similar to their respective modified materials. The probability of scrap material recognition rate, i.e., the theoretical sorting efficiency between PP and PP-EPDM, could reach about 50%, and between ABS and ABS-PC it could reach about 75% with diameters ranging from 14 mm to 23 mm, and with exclusion of abnormal impacts, the actual separation rates were 39.2% for PP, 41.4% for PP/EPDM scraps as well as 62.4% for ABS, and 70.8% for ABS/PC scraps. Within the diameter range of 8-13 mm, only 25% of PP and 27% of PP/EPDM scraps, as well as 43% of ABS, and 47% of ABS/PC scraps were finally separated. This research proposes a new approach for sensor-aided automatic recognition and sorting of black plastic materials, it is an effective method for ASR reduction and recycling. PMID:28594341

Study on Impact Acoustic-Visual Sensor-Based Sorting of ELV Plastic Materials.

PubMed

Huang, Jiu; Tian, Chuyuan; Ren, Jingwei; Bian, Zhengfu

2017-06-08

This paper concentrates on a study of a novel multi-sensor aided method by using acoustic and visual sensors for detection, recognition and separation of End-of Life vehicles' (ELVs) plastic materials, in order to optimize the recycling rate of automotive shredder residues (ASRs). Sensor-based sorting technologies have been utilized for material recycling for the last two decades. One of the problems still remaining results from black and dark dyed plastics which are very difficult to recognize using visual sensors. In this paper a new multi-sensor technology for black plastic recognition and sorting by using impact resonant acoustic emissions (AEs) and laser triangulation scanning was introduced. A pilot sorting system which consists of a 3-dimensional visual sensor and an acoustic sensor was also established; two kinds commonly used vehicle plastics, polypropylene (PP) and acrylonitrile-butadiene-styrene (ABS) and two kinds of modified vehicle plastics, polypropylene/ethylene-propylene-diene-monomer (PP-EPDM) and acrylonitrile-butadiene-styrene/polycarbonate (ABS-PC) were tested. In this study the geometrical features of tested plastic scraps were measured by the visual sensor, and their corresponding impact acoustic emission (AE) signals were acquired by the acoustic sensor. The signal processing and feature extraction of visual data as well as acoustic signals were realized by virtual instruments. Impact acoustic features were recognized by using FFT based power spectral density analysis. The results shows that the characteristics of the tested PP and ABS plastics were totally different, but similar to their respective modified materials. The probability of scrap material recognition rate, i.e., the theoretical sorting efficiency between PP and PP-EPDM, could reach about 50%, and between ABS and ABS-PC it could reach about 75% with diameters ranging from 14 mm to 23 mm, and with exclusion of abnormal impacts, the actual separation rates were 39.2% for PP, 41.4% for PP/EPDM scraps as well as 62.4% for ABS, and 70.8% for ABS/PC scraps. Within the diameter range of 8-13 mm, only 25% of PP and 27% of PP/EPDM scraps, as well as 43% of ABS, and 47% of ABS/PC scraps were finally separated. This research proposes a new approach for sensor-aided automatic recognition and sorting of black plastic materials, it is an effective method for ASR reduction and recycling.

Wireless radiation sensor

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

Lamberti, Vincent E.; Howell, Jr, Layton N.; Mee, David K.

Disclosed is a sensor for detecting radiation. The sensor includes a ferromagnetic metal and a radiation sensitive material coupled to the ferromagnetic metal. The radiation sensitive material is operable to change a tensile stress of the ferromagnetic metal upon exposure to radiation. The radiation is detected based on changes in the magnetic switching characteristics of the ferromagnetic metal caused by the changes in the tensile stress.

A pH Sensor Based on a Stainless Steel Electrode Electrodeposited with Iridium Oxide

ERIC Educational Resources Information Center

Martinez, C. C. M.; Madrid, R. E.; Felice, C. J.

2009-01-01

A simple procedure to make an iridium oxide (IrO[subscript 2]) electrodeposited pH sensor, that can be used in a chemical, biomedical, or materials laboratory, is presented here. Some exercises, based on this sensor, that can be used to teach important concepts in the field of biomedical, biochemical, tissue, or materials engineering, are also…

Application of IDT Sensors for Structural Health Monitoring of Windmill Turbine Blades Made of Composite Material

NASA Astrophysics Data System (ADS)

Nalladega, V.; Na, J. K.; Druffner, C.

2011-06-01

Interdigital transducers (IDT) generate and receive ultrasonic surface waves without the complexity involved with secondary devices such as angled wedges or combs. The IDT sensors have been successfully applied for the NDE of homogeneous materials like metals in order to detect cracks and de-bond. However, these transducers have not been yet adapted for complex and anisotropic materials like fiber-reinforced composites. This work presents the possibility of using IDT sensors for monitoring structural damages in wind turbine blades, typically made of fiberglass composites. IDT sensors with a range of operating frequency between 250 kHz and 1 MHz are initially tested on representative composite test panels for ultrasonic surface wave properties including beam spread, propagation distance and effect of material's anisotropy. Based on these results, an optimum frequency range for the IDT sensor is found to be 250-500 kHz. Subsequently, IDT sensors with operating frequency 500 kHz are used to detect and quantify artificial defects created in the composite test samples. Discussions are made on the interaction of ultrasonic fields with these defects along with the effects of fiber directionality and composite layer stacking.

Vitex negundo inhibits cyclooxygenase-2 inflammatory cytokine-mediated inflammation on carrageenan-induced rat hind paw edema

PubMed Central

Chattopadhyay, Pronobesh; Hazarika, Soilyadhar; Dhiman, Sunil; Upadhyay, Aadesh; Pandey, Anurag; Karmakar, Sanjeev; Singh, Lokendra

2012-01-01

Background: Vitex negundo L. (Verbenaceae) is a hardy plant widely distributed in the Indian subcontinent and used for treatment of a wide spectrum of health disorders in traditional and folk medicine, some of which have been experimentally validated. In present study, we aimed to investigate the anti-inflammatory effects of V. negundo in carrageenan-induced paw edema in rats, and to investigate the probable mechanism of anti-inflammatory action. Materials and Methods: Paw edema was produced by injecting 1% solution of carrageenan, and the paw volume was measured before and after carrageenan injection up to 5 h. V. negundo leaf oil was extracted using a Clevenger apparatus and administered by a trans-dermal route to Wistar rats and the percentage of inhibition of inflammation was observed using a Plethysmometer by comparing a compound aerosol-based formulation with 1 mg diclofinac diethylamine BP and 7 mg methyl salicylate IP/kg body weight served as a standard drug whereas paraffin oil served as the placebo group. After withdrawing of blood, serum was separated and cyclooxygenase (COX)-1 and COX-2 inhibitory activities were measured by the enzyme immuno assay (EIA) method by using a COX inhibitor screening assay kit. Results and Discussion: V. negundo leaf oil significantly (P < 0.05) reduced the carrageenan-induced paw edema as compared to the placebo group (paraffin oil) and 1 mg diclofinac diethylamine BP and 7 mg methyl salicylate IP showed the maximum inhibition of paw edema as compared to the V. negundo leaf oil treated group and the control group. Also in the present study V. negundo leaf oil showed significantly (P < 0.05) inhibits COX-1 pathways rather than COX-2 pathways as compared to the V. negundo leaf oil treated group. Conclusion: It is suggested that the V. negundo leaf oil is a potent anti-inflammatory agent and acts via inhibition of COX-2 without much interfering COX-1 pathways. PMID:22923950

The Expression and Significance of Feces Cyclooxygensae-2 mRNA in Colorectal Cancer and Colorectal Adenomas

PubMed Central

Li, Xiaofeng; Kong, Lixia; Liao, Suhuan; Lu, Jing; Ma, Lin; Long, Xiaohua

2017-01-01

Background/Aim: This study aims to explore the expression and significance of feces cyclooxygensae-2 (COX-2) mRNA in colorectal cancer and colorectal adenomas. Materials and Methods: The expression of feces COX-2 mRNA in colorectal cancer (n = 28), colorectal adenomas (n = 54), and normal control group (n = 11) were examined by reverse transcriptase polymerase chain reaction (RT-PCR). The positive rate of fecal occult blood test (FOBT) were detected in colorectal cancer (n = 30), colorectal adenomas (n = 56), and normal control group (n = 11); the sensitivity of the two methods was also compared. Results: The positive rate of feces COX-2 mRNA in colorectal cancer was 82.1% (25/28), which was significantly higher than colorectal adenomas 59.3% (32/54), and normal tissues 18.2% (2/11), the difference being significant between the three groups (χ2= 13.842, P = 0.001). The positive rate of FOBT in colorectal cancer was 73.3% (10/30), which was significantly higher than colorectal adenomas 10.7% (6/56) and normal tissues 9.1% (1/11), the difference being significant between these three groups (χ2= 7.525, P = 0.023). There was no significant association between feces COX-2 expression and various clinical pathological features of colorectal cancer and colorectal adenomas (P > 0.05). The sensitivity of the RT-PCR method is higher than FOBT, however, the specificity of FOBT is slightly higher than RT-PCR. Conclusions: High expression of feces COX-2 mRNA in colorectal adenomas and colorectal cancer is a common event; it is an early event in the development of colorectal adenomas to colorectal cancer. Feces COX-2 mRNA has a high sensitivity for detect colorectal cancer; combination with FOBT will be the best alternative. Feces COX-2 can be potentially used in the early diagnosis and screening of colorectal cancer. PMID:28139497

Celecoxib Induced Tumor Cell Radiosensitization by Inhibiting Radiation Induced Nuclear EGFR Transport and DNA-Repair: A COX-2 Independent Mechanism

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

Dittmann, Klaus H.; Mayer, Claus; Ohneseit, Petra A.

2008-01-01

Purpose: The purpose of the study was to elucidate the molecular mechanisms mediating radiosensitization of human tumor cells by the selective cyclooxygenase (COX)-2 inhibitor celecoxib. Methods and Materials: Experiments were performed using bronchial carcinoma cells A549, transformed fibroblasts HH4dd, the FaDu head-and-neck tumor cells, the colon carcinoma cells HCT116, and normal fibroblasts HSF7. Effects of celecoxib treatment were assessed by clonogenic cell survival, Western analysis, and quantification of residual DNA damage by {gamma}H{sub 2}AX foci assay. Results: Celecoxib treatment resulted in a pronounced radiosensitization of A549, HCT116, and HSF7 cells, whereas FaDu and HH4dd cells were not radiosensitized. The observedmore » radiosensitization could neither be correlated with basal COX-2 expression pattern nor with basal production of prostaglandin E2, but was depended on the ability of celecoxib to inhibit basal and radiation-induced nuclear transport of epidermal growth factor receptor (EGFR). The nuclear EGFR transport was strongly inhibited in A549-, HSF7-, and COX-2-deficient HCT116 cells, which were radiosensitized, but not in FaDu and HH4dd cells, which resisted celecoxib-induced radiosensitization. Celecoxib inhibited radiation-induced DNA-PK activation in A549, HSF7, and HCT116 cells, but not in FaDu and HH4dd cells. Consequentially, celecoxib increased residual {gamma}H2AX foci after irradiation, demonstrating that inhibition of DNA repair has occurred in responsive A549, HCT116, and HSF7 cells only. Conclusions: Celecoxib enhanced radiosensitivity by inhibition of EGFR-mediated mechanisms of radioresistance, a signaling that was independent of COX-2 activity. This novel observation may have therapeutic implications such that COX-2 inhibitors may improve therapeutic efficacy of radiation even in patients whose tumor radioresistance is not dependent on COX-2.« less

Epigallocatechin-3-gallate blocks triethylene glycol dimethacrylate-induced cyclooxygenase-2 expression by suppressing extracellular signal-regulated kinase in human dental pulp and embryonic palatal mesenchymal cells.

PubMed

Yang, Wan-Hsien; Deng, Yi-Ting; Kuo, Mark Yen-Ping; Liu, Cheing-Meei; Chang, Hao-Hueng; Chang, Jenny Zwei-Chieng

2013-11-01

Methacrylate resin-based materials could release components into adjacent environment even after polymerization. The major components leached include triethylene glycol dimethacrylate (TEGDMA). TEGDMA has been shown to induce the expression of cyclooxygenase-2 (COX-2). However, the mechanisms are not completely understood. The aims of this study were to investigate the molecular mechanism underlying TEGDMA-induced COX-2 in 2 oral cell types, the primary culture of human dental pulp (HDP) cells and the human embryonic palatal mesenchymal (HEPM) pre-osteoblasts, and to propose potential strategy to prevent or ameliorate the TEGDMA-induced inflammation in oral tissues. TEGDMA-induced COX-2 expression and its signaling pathways were assessed by Western blot analyses in HDP and HEPM cells. The inhibition of TEGDMA-induced COX-2 protein expression using various dietary phytochemicals was investigated. COX-2 protein expression was increased after exposure to TEGDMA at concentrations as low as 5 μmol/L. TEGDMA-induced COX-2 expression was associated with reaction oxygen species, the extracellular signal-regulated kinase 1/2, and the p38 mitogen-activated protein kinase signaling pathways in HDP and HEPM cells. The activation of p38 mitogen-activated protein kinase was directly associated with reactive oxygen species. Epigallocatechin-3-gallate suppressed TEGDMA-induced COX-2 expression by inhibiting phosphorylation of extracellular signal-regulated kinase 1/2. Cells exposed to low concentrations of TEGDMA may induce inflammatory responses of the adjacent tissues, and this should be taken into consideration during common dental practice. Green tea, which has a long history of safe beverage consumption, may be a useful agent for the prevention or treatment of TEGDMA-induced inflammation in oral tissues. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Polydimethylsiloxane-fabricated optical fiber sensor capable of measuring both large axial and shear strain

NASA Astrophysics Data System (ADS)

Shen, Yu; Wang, Ziyuan; Wen, Huaihai; Zhou, Zhi

2014-11-01

Fiber optic sensor (FOS) has received much attention in the field of Structure Health Monitoring (SHM) due to its advantages of low weight, small size, high sensitivity multiplexing ability, free of electromagnetic interference and long durability. However, in harsh environments, structures often undergo large strain where few traditional fiber optic sensors could survive. This paper report a novel material with features of light-transparent, chemically inert, thermally stable material Polydimethylsiloxane(PDMS) fabricated large axial/shearing strain sensor. The sensor was fabricated by directly coupling a conventional signal mode fiber into half cured PDMS material using a translation stage under the inspection of a microscope. Meanwhile, a laser diode and a photo detector were used in the fabrication process to make sure the sensor achieved minimum light loss. An experiment was conducted later to investigate the sensor's transmission characteristic in 1310nm infrared laser relating with the applied axial/shearing strain. The results show that the proposed sensor survived an axial strain of 6 7.79 x 106 μɛ ; a shear of 4 6.49 x 104 μɛ with good linearity and repetition. The experiment indicates that the proposed sensor can potentially be used as strain sensing elements in Structure Health Monitoring systems under earthquake or explosion.

Monitoring technology

NASA Technical Reports Server (NTRS)

Stevenson, William A. (Inventor)

1989-01-01

A process for infrared spectroscopic monitoring of insitu compositional changes in a polymeric material comprises the steps of providing an elongated infrared radiation transmitting fiber that has a transmission portion and a sensor portion, embedding the sensor portion in the polymeric material to be monitored, subjecting the polymeric material to a processing sequence, applying a beam of infrared radiation to the fiber for transmission through the transmitting portion to the sensor portion for modification as a function of properties of the polymeric material, monitoring the modified infrared radiation spectra as the polymeric material is being subjected to the processing sequence to obtain kinetic data on changes in the polymeric material during the processing sequence, and adjusting the processing sequence as a function of the kinetic data provided by the modified infrared radiation spectra information.

Monitoring technology

NASA Technical Reports Server (NTRS)

Stevenson, William A. (Inventor)

1992-01-01

A process for infrared spectroscopic monitoring of insitu compositional changes in a polymeric material comprises the steps of providing an elongated infrared radiation transmitting fiber that has a transmission portion and a sensor portion, embedding the sensor portion in the polymeric material to be monitored, subjecting the polymeric material to a processing sequence, applying a beam of infrared radiation to the fiber for transmission through the transmitting portion to the sensor portion for modification as a function of properties of the polymeric material, monitoring the modified infrared radiation spectra as the polymeric material is being subjected to the processing sequence to obtain kinetic data on changes in the polymeric material during the processing sequence, and adjusting the processing sequence as a function of the kinetic data provided by the modified infrared radiation spectra information.

The value of cyclooxygenase-2 expression in differentiating between early melanomas and histopathologically difficult types of benign human skin lesions.

PubMed

Kuźbicki, Łukasz; Lange, Dariusz; Strączyńska-Niemiec, Anita; Chwirot, Barbara W

2012-02-01

Early cutaneous melanomas may present a substantial diagnostic challenge. We have already reported that expression of cyclooxygenase-2 (COX-2) may be useful for differentiating between cutaneous melanomas and naevi. The purpose of this study was to examine the value of COX-2 in a challenging task of differential diagnosis of early melanomas and melanocytic naevi considered by histopathologists as morphologically difficult to unequivocally diagnose as benign lesions. The material for the study comprised formalin-fixed paraffin-embedded samples of 46 naevi (including 27 cases of dysplastic, Spitz and Reed naevi) and 30 early human cutaneous melanomas. The expression of COX-2 was detected immunohistochemically. Melanomas expressed COX-2 significantly more strongly compared with naevi. The test, on the basis of determination of the percentage fractions of COX-2-positive cells, allows for differentiation of early skin melanomas and naevi with high sensitivity and specificity. Receiver operating characteristic analysis of the test results yielded areas under receiver operating characteristics curves (AUC)=0.946±0.030 for central regions and AUC=0.941±0.031 for the peripheries of the lesions. The performance of the test in differentiating between melanomas and the naevi group comprising dysplastic, Spitz and Reed naevi was also good, with AUC=0.933±0.034 and 0.923±0.037 for the central and the border regions of the lesions, respectively. Using a more complex diagnostic algorithm also accounting for the staining intensity did not result in an improvement in the resolving power of the assay. A diagnostic algorithm using differences in the percentage fractions of cells expressing COX-2 may serve as a useful tool in aiding the differential diagnosis of 'histopathologically difficult' benign melanocytic skin lesions and early melanomas.

Fabrication of a Porous Fiber Cladding Material Using Microsphere Templating for Improved Response Time with Fiber Optic Sensor Arrays

PubMed Central

Henning, Paul E.; Rigo, M. Veronica; Geissinger, Peter

2012-01-01

A highly porous optical-fiber cladding was developed for evanescent-wave fiber sensors, which contains sensor molecules, maintains guiding conditions in the optical fiber, and is suitable for sensing in aqueous environments. To make the cladding material (a poly(ethylene) glycol diacrylate (PEGDA) polymer) highly porous, a microsphere templating strategy was employed. The resulting pore network increases transport of the target analyte to the sensor molecules located in the cladding, which improves the sensor response time. This was demonstrated using fluorescein-based pH sensor molecules, which were covalently attached to the cladding material. Scanning electron microscopy was used to examine the structure of the templated polymer and the large network of interconnected pores. Fluorescence measurements showed a tenfold improvement in the response time for the templated polymer and a reliable pH response over a pH range of five to nine with an estimated accuracy of 0.08 pH units. PMID:22654644

Inkjet-Printed Graphene/PEDOT:PSS Temperature Sensors on a Skin-Conformable Polyurethane Substrate.

PubMed

Vuorinen, Tiina; Niittynen, Juha; Kankkunen, Timo; Kraft, Thomas M; Mäntysalo, Matti

2016-10-18

Epidermal electronic systems (EESs) are skin-like electronic systems, which can be used to measure several physiological parameters from the skin. This paper presents materials and a simple, straightforward fabrication process for skin-conformable inkjet-printed temperature sensors. Epidermal temperature sensors are already presented in some studies, but they are mainly fabricated using traditional photolithography processes. These traditional fabrication routes have several processing steps and they create a substantial amount of material waste. Hence utilizing printing processes, the EES may become attractive for disposable systems by decreasing the manufacturing costs and reducing the wasted materials. In this study, the sensors are fabricated with inkjet-printed graphene/PEDOT:PSS ink and the printing is done on top of a skin-conformable polyurethane plaster (adhesive bandage). Sensor characterization was conducted both in inert and ambient atmosphere and the graphene/PEDOT:PSS temperature sensors (thermistors) were able reach higher than 0.06% per degree Celsius sensitivity in an optimal environment exhibiting negative temperature dependence.

Recent Advances in Polymeric Materials Used as Electron Mediators and Immobilizing Matrices in Developing Enzyme Electrodes

PubMed Central

Moyo, Mambo; Okonkwo, Jonathan O.; Agyei, Nana M.

2012-01-01

Different classes of polymeric materials such as nanomaterials, sol-gel materials, conducting polymers, functional polymers and biomaterials have been used in the design of sensors and biosensors. Various methods have been used, for example from direct adsorption, covalent bonding, crossing-linking with glutaraldehyde on composites to mixing the enzymes or use of functionalized beads for the design of sensors and biosensors using these polymeric materials in recent years. It is widely acknowledged that analytical sensing at electrodes modified with polymeric materials results in low detection limits, high sensitivities, lower applied potential, good stability, efficient electron transfer and easier immobilization of enzymes on electrodes such that sensing and biosensing of environmental pollutants is made easier. However, there are a number of challenges to be addressed in order to fulfill the applications of polymeric based polymers such as cost and shortening the long laboratory synthetic pathways involved in sensor preparation. Furthermore, the toxicological effects on flora and fauna of some of these polymeric materials have not been well studied. Given these disadvantages, efforts are now geared towards introducing low cost biomaterials that can serve as alternatives for the development of novel electrochemical sensors and biosensors. This review highlights recent contributions in the development of the electrochemical sensors and biosensors based on different polymeric material. The synergistic action of some of these polymeric materials and nanocomposites imposed when combined on electrode during sensing is discussed. PMID:22368503

Development and performance research of FBG strain sensor for monitoring on asphalt concrete pavement

NASA Astrophysics Data System (ADS)

Hu, Qingli; Wang, Chuan; Ou, Jinping

2010-04-01

Stiffness of asphalt concrete is very low, so ordinary FRP or steel packaged sensors are not suitable for measuring its strain accurately. In view of the problem, one innovative kind of optical fiber Bragg grating sensor packaged with polypropylene, a thermoplastic resin, was proposed in this article. Firstly, a conveniently assembled and dissembled steel die was designed and fabricated. Then, after characteristics study of polypropylene during heating and cooling repeatedly, the reliable grouting technique was formed. After this, real-time monitor of the entire sensor packaging process including die apartness was performed, and then, the sensor mechanics performance, the microscopic structure and other properties were studied thoroughly. Results of SEM indicate that interface of optical fiber and polypropylene is considerable tight. Measured strain during sensor making is reasonable. The FBG sensor was also embedded into a concrete column to measure its strain during continuously 7 day-long early-age solidification and compressive strain. Additionally, the FBG was also used to measure strain of asphalt concrete beam. Linearity and repeatability of the sensors are quit well and measured strains are quite believable. So, we can say that due to deformation compatibility between packaged material and FBG, FBG sensor and be measured material, especially low modulus of packaging materials, the strain of asphalt pavement can be monitored reliably by the sensor.

Beyond graphene: Electrochemical sensors and biosensors for biomarkers detection.

PubMed

Bollella, Paolo; Fusco, Giovanni; Tortolini, Cristina; Sanzò, Gabriella; Favero, Gabriele; Gorton, Lo; Antiochia, Riccarda

2017-03-15

Graphene's success has stimulated great interest and research in the synthesis and characterization of graphene-like 2D materials, single and few-atom-thick layers of van der Waals materials, which show fascinating and technologically useful properties. This review presents an overview of recent electrochemical sensors and biosensors based on graphene and on graphene-like 2D materials for biomarkers detection. Initially, we will outline different electrochemical sensors and biosensors based on chemically derived graphene, including graphene oxide and reduced graphene oxide, properly functionalized for improved performances and we will discuss the various strategies to prepare graphene modified electrodes. Successively, we present electrochemical sensors and biosensors based on graphene-like 2D materials, such as boron nitride (BN), graphite-carbon nitride (g-C 3 N 4 ), transition metal dichalcogenides (TMDs), transition metal oxides and graphane, outlining how the new modified 2D nanomaterials will improve the electrochemical performances. Finally, we will compare the results obtained with different sensors and biosensors for the detection of important biomarkers such as glucose, hydrogen peroxide and cancer biomarkers and highlight the advantages and disadvantages of the use of graphene and graphene-like 2D materials in different sensing platforms. Copyright © 2016 Elsevier B.V. All rights reserved.

Integrated ion sensor device applications based on printed hybrid material systems (Conference Presentation)

NASA Astrophysics Data System (ADS)

List-Kratochvil, Emil J. W.

2016-09-01

Comfortable, wearable sensors and computers will enhance every person's awareness of his or her health condition, environment, chemical pollutants, potential hazards, and information of interest. In agriculture and in the food industry there is a need for a constant control of the condition and needs of plants, animals, and farm products. Yet many of these applications depend upon the development of novel, cheap devices and sensors that are easy to implement and to integrate. Organic semiconductors as well as several inorganic materials and hybrid material systems have proven to combine a number of intriguing optical and electronic properties with simple processing methods. As it will be reviewed in this contribution, these materials are believed to find their application in printed electronic devices allowing for the development of smart disposable devices in food-, health-, and environmental monitoring, diagnostics and control, possibly integrated into arrays of sensor elements for multi-parameter detection. In this contribution we review past and recent achievements in the field. Followed by a brief introduction, we will focus on two topics being on the agenda recently: a) the use of electrolyte-gated organic field-effect transistor (EGOFET) and ion-selective membrane based sensors for in-situ sensing of ions and biological substances and b) the development of hybrid material based resistive switches and their integration into fully functional, printed hybrid crossbar sensor array structures.

Three Dimensional Distribution of Sensitive Field and Stress Field Inversion of Force Sensitive Materials under Constant Current Excitation.

PubMed

Zhao, Shuanfeng; Liu, Min; Guo, Wei; Zhang, Chuanwei

2018-02-28

Force sensitive conductive composite materials are functional materials which can be used as the sensitive material of force sensors. However, the existing sensors only use one-dimensional electrical properties of force sensitive conductive materials. Even in tactile sensors, the measurement of contact pressure is achieved by large-scale arrays and the units of a large-scale array are also based on the one-dimensional electrical properties of force sensitive materials. The main contribution of this work is to study the three-dimensional electrical properties and the inversion method of three-dimensional stress field of a force sensitive material (conductive rubber), which pushes the application of force sensitive material from one dimensional to three-dimensional. First, the mathematical model of the conductive rubber current field distribution under a constant force is established by the effective medium theory, and the current field distribution model of conductive rubber with different geometry, conductive rubber content and conductive rubber relaxation parameters is deduced. Secondly, the inversion method of the three-dimensional stress field of conductive rubber is established, which provides a theoretical basis for the design of a new tactile sensor, three-dimensional stress field and space force based on force sensitive materials.

Method and apparatus for determination of material residual stress

NASA Technical Reports Server (NTRS)

Chern, Engmin J. (Inventor); Flom, Yury (Inventor)

1993-01-01

A device for the determination of residual stress in a material sample consisting of a sensor coil, adjacent to the material sample, whose resistance varies according to the amount of stress within the material sample, a mechanical push-pull machine for imparting a gradually increasing compressional and tensional force on the material sample, and an impedance gain/phase analyzer and personal computer (PC) for sending an input signal to and receiving an input signal from the sensor coil is presented. The PC will measure and record the change in resistance of the sensor coil and the corresponding amount of strain of the sample. The PC will then determine, from the measurements of change of resistance and corresponding strain of the sample, the point at which the resistance of the sensor coil is at a minimum and the corresponding value and type of strain of the sample at that minimum resistance point, thereby, enabling a calculation of the residual stress in the sample.

Sensor arrays for detecting analytes in fluids

NASA Technical Reports Server (NTRS)

Freund, Michael S. (Inventor); Lewis, Nathan S. (Inventor)

2000-01-01

A sensor array for detecting an analyte in a fluid, comprising at least first and second chemically sensitive resistors electrically connected to an electrical measuring apparatus, wherein each of the chemically sensitive resistors comprises a mixture of nonconductive material and a conductive material. Each resistor provides an electrical path through the mixture of nonconductive material and the conductive material. The resistors also provide a difference in resistance between the conductive elements when contacted with a fluid comprising an analyte at a first concentration, than when contacted with an analyte at a second different concentration. A broad range of analytes can be detected using the sensors of the present invention. Examples of such analytes include, but are not limited to, alkanes, alkenes, alkynes, dienes, alicyclic hydrocarbons, arenes, alcohols, ethers, ketones, aldehydes, carbonyls, carbanions, polynuclear aromatics, organic derivatives, biomolecules, sugars, isoprenes, isoprenoids and fatty acids. Moreover, applications for the sensors of the present invention include, but are not limited to, environmental toxicology, remediation, biomedicine, material quality control, food monitoring and agricultural monitoring.

Acoustic calibration apparatus for calibrating plethysmographic acoustic pressure sensors

NASA Technical Reports Server (NTRS)

Zuckerwar, Allan J. (Inventor); Davis, David C. (Inventor)

1995-01-01

An apparatus for calibrating an acoustic sensor is described. The apparatus includes a transmission material having an acoustic impedance approximately matching the acoustic impedance of the actual acoustic medium existing when the acoustic sensor is applied in actual in-service conditions. An elastic container holds the transmission material. A first sensor is coupled to the container at a first location on the container and a second sensor coupled to the container at a second location on the container, the second location being different from the first location. A sound producing device is coupled to the container and transmits acoustic signals inside the container.

Acoustic calibration apparatus for calibrating plethysmographic acoustic pressure sensors

NASA Technical Reports Server (NTRS)

Zuckerwar, Allan J. (Inventor); Davis, David C. (Inventor)

1994-01-01

An apparatus for calibrating an acoustic sensor is described. The apparatus includes a transmission material having an acoustic impedance approximately matching the acoustic impedance of the actual acoustic medium existing when the acoustic sensor is applied in actual in-service conditions. An elastic container holds the transmission material. A first sensor is coupled to the container at a first location on the container and a second sensor coupled to the container at a second location on the container, the second location being different from the first location. A sound producing device is coupled to the container and transmits acoustic signals inside the container.

Army Research Laboratory S&T Campaign Plans 2015-2035

DTIC Science & Technology

2014-09-01

addressing propagation effects, impact of wind noise on detection range and angular accuracy. Use of vector sensors is one approach for potential advances...for the future warfighter, such as new protective and responsive materials, sensors , and munitions. Polymer Chemistry explores the molecular-level...ultimately enable the design and development of novel materials, molecular sensors , and nanoscale machines that exploit the exceptional capabilities of

Radio Frequency Identification (RFID) Based Corrosion Monitoring Sensors. Part 2: Application and Testing of the Coating Materials

DTIC Science & Technology

2014-12-22

Radio frequency identification ( RFID ) based corrosion monitoring sensors: Part II Application and testing of the coating materials Youliang He1...email: yohe@nrcan.gc.ca Keywords: Corrosion monitoring; Wireless sensor; RFID ; Electromagnetic interference; Coating. Abstract Cost-effective...Radio Frequency Identification ( RFID ) transponders (tags) were investigated for wireless corrosion monitoring by applying a metal-filled conductive

Luminescence materials for pH and oxygen sensing in microbial cells - structures, optical properties, and biological applications.

PubMed

Zou, Xianshao; Pan, Tingting; Chen, Lei; Tian, Yanqing; Zhang, Weiwen

2017-09-01

Luminescence including fluorescence and phosphorescence sensors have been demonstrated to be important for studying cell metabolism, and diagnosing diseases and cancer. Various design principles have been employed for the development of sensors in different formats, such as organic molecules, polymers, polymeric hydrogels, and nanoparticles. The integration of the sensing with fluorescence imaging provides valuable tools for biomedical research and applications at not only bulk-cell level but also at single-cell level. In this article, we critically reviewed recent progresses on pH, oxygen, and dual pH and oxygen sensors specifically for their application in microbial cells. In addition, we focused not only on sensor materials with different chemical structures, but also on design and applications of sensors for better understanding cellular metabolism of microbial cells. Finally, we also provided an outlook for future materials design and key challenges in reaching broad applications in microbial cells.

The Development of Metal Oxide Chemical Sensing Nanostructures

NASA Technical Reports Server (NTRS)

Hunter, G. W.; VanderWal,R. L.; Xu, J. C.; Evans, L. J.; Berger, G. M.; Kulis, M. J.

2008-01-01

This paper discusses sensor development based on metal oxide nanostructures and microsystems technology. While nanostructures such as nanowires show significant potential as enabling materials for chemical sensors, a number of significant technical challenges remain. This paper discusses development to address each of these technical barriers: 1) Improved contact and integration of the nanostructured materials with microsystems in a sensor structure; 2) Control of nanostructure crystallinity to allow control of the detection mechanism; and 3) Widening the range of gases that can be detected by fabricating multiple nanostructured materials. A sensor structure composed of three nanostructured oxides aligned on a single microsensor has been fabricated and tested. Results of this testing are discussed and future development approaches are suggested. It is concluded that while this work lays the foundation for further development, these are the beginning steps towards realization of repeatable, controlled sensor systems using oxide based nanostructures.

Radio frequency and capacitive sensors for dielectric characterization of low-conductivity media

NASA Astrophysics Data System (ADS)

Sheldon, Robert T.

Low-conductivity media are found in a vast number of applications, for example as electrical insulation or as the matrix polymer in high strength-to-weight ratio structural composites. In some applications, these materials are subjected to extreme environmental, thermal, and mechanical conditions that can affect the material's desired performance. In a more general sense, a medium may be comprised of one or more layers with unknown material properties that may affect the desired performance of the entire structure. It is often, therefore, of great import to be able to characterize the material properties of these media for the purpose of estimating their future performance in a certain application. Low-conductivity media, or dielectrics, are poor electrical conductors and permit electromagnetic waves and static electric fields to pass through with minimal attenuation. The amount of electrical energy that may be stored (and lost) in these fields depends directly upon the material property, permittivity, which is generally complex, frequency-dependent and has a measurable effect on sensors designed to characterize dielectric media. In this work, two different types of dielectric sensors: radio frequency resonant antennas and lower-frequency (<1 MHz) capacitive sensors, are designed for permittivity characterization in their respective frequency regimes. In the first part of this work, the capability of characterizing multilayer dielectric structures is studied using a patch antenna, a type of antenna that is primarily designed for data communications in the microwave bands but has application in the field of nondestructive evaluation as well. Each configuration of a patch antenna has a single lowest resonant (dominant mode) frequency that is dependent upon the antenna's substrate material and geometry as well as the permittivity and geometry of exterior materials. Here, an extant forward model is validated using well-characterized microwave samples and a new method of resonant frequency and quality factor determination from measured data is presented. Excellent agreement between calculated and measured values of sensor resonant frequency was obtained for the samples studied. Agreement between calculated and measured quality factor was good in some cases but incurred the particular challenge of accurately quantifying multiple contributions to loss from the sensor structure itself, which at times dominates the contribution due to the sample material. Two later chapters describe the development of capacitive sensors to quantify the low-frequency changes in material permittivity due to environmental aging mechanisms. One embodiment involves the application of coplanar concentric interdigital electrode sensors for the purpose of investigating polymer-matrix degradation in glass-fiber composites due to isothermal aging. Samples of bismaleimide-matrix glass-fiber composites were aged at several high temperatures to induce thermal degradation and capacitive sensors were used to measure the sensor capacitance and dissipation factor, parameters that are directly proportional to the real and imaginary components of complex permittivity, respectively. It was shown that real permittivity and dissipation factor decreased with increasing aging temperature, a trend that was common to both interdigital sensor measurements and standard parallel plate electrode measurements. The second piece of work involves the development of cylindrical interdigital electrode sensors to characterize complex permittivity changes in wire insulation due to aging-related degradation. The sensor was proven effective in detecting changes in irradiated nuclear power plant wiring insulation and in aircraft wiring insulation due to liquid chemical immersion. In all three cases, the results indicate a clear correlation of measured capacitance and dissipation factor with increased degradation.

Stable optical oxygen sensing materials based on click-coupling of fluorinated platinum(II) and palladium(II) porphyrins—A convenient way to eliminate dye migration and leaching

PubMed Central

Koren, Klaus; Borisov, Sergey M.; Klimant, Ingo

2012-01-01

Nucleophilic substitution of the labile para-fluorine atoms of 2,3,4,5,6-pentafluorophenyl groups enables a click-based covalent linkage of an oxygen indicator (platinum(II) or palladium(II) 5,10,15,20-meso-tetrakis-(2,3,4,5,6-pentafluorophenyl)-porphyrin) to the sensor matrix. Copolymers of styrene and pentafluorostyrene are chosen as polymeric materials. Depending on the reaction conditions either soluble sensor materials or cross-linked microparticles are obtained. Additionally, we prepared Ormosil-based sensors with linked indicator, which showed very high sensitivity toward oxygen. The effect of covalent coupling on sensor characteristics, stability and photophysical properties is studied. It is demonstrated that leaching and migration of the dye are eliminated in the new materials but excellent photophysical properties of the indicators are preserved. PMID:23576845

Investigating the binding properties of porous drug delivery systems using nuclear sensors (radiotracers) and positron annihilation lifetime spectroscopy--predicting conditions for optimum performance.

PubMed

Mume, Eskender; Lynch, Daniel E; Uedono, Akira; Smith, Suzanne V

2011-06-21

Understanding how the size, charge and number of available pores in porous material influences the uptake and release properties is important for optimising their design and ultimately their application. Unfortunately there are no standard methods for screening porous materials in solution and therefore formulations must be developed for each encapsulated agent. This study investigates the potential of a library of radiotracers (nuclear sensors) for assessing the binding properties of hollow silica shell materials. Uptake and release of Cu(2+) and Co(2+) and their respective complexes with polyazacarboxylate macrocycles (dota and teta) and a series of hexa aza cages (diamsar, sarar and bis-(p-aminobenzyl)-diamsar) from the hollow silica shells was monitored using their radioisotopic analogues. Coordination chemistry of the metal (M) species, subtle alterations in the molecular architecture of ligands (Ligand) and their resultant complexes (M-Ligand) were found to significantly influence their uptake over pH 3 to 9 at room temperature. Positively charged species were selectively and rapidly (within 10 min) absorbed at pH 7 to 9. Negatively charged species were preferentially absorbed at low pH (3 to 5). Rates of release varied for each nuclear sensor, and time to establish equilibrium varied from minutes to days. The subtle changes in design of the nuclear sensors proved to be a valuable tool for determining the binding properties of porous materials. The data support the development of a library of nuclear sensors for screening porous materials for use in optimising the design of porous materials and the potential of nuclear sensors for high through-put screening of materials.

Triboluminescent Materials for Smart Optical Damage Sensors for Space Applications

NASA Technical Reports Server (NTRS)

Aggarwal, M. D.; Penn, B. G.; Miller, J.; Sadate, S.; Batra, A. K.

2008-01-01

There is a need to develop a new technique of damage detection for composites, which could detect cracking or delamination from any desired location within a material structure in real time. Recently, triboluminescent materials have been proposed as smart sensors of structural damage. To sense the damage, these materials can be epoxy bonded, coated in a polymer matrix, or embedded in a composite host structure. When the damage or fracture takes place in the host structure, the resultant fracture of triboluminescent crystals creates a light emission. This will warn in real time that structural damage has occurred. The triboluminescent emission of the candidate phosphor has to be bright enough that the light reaching from the point of fracture to the detector through a fiber optic cable is detectable. There are a large number of triboluminescent materials, but few satisfy the above criterion. The authors have synthesized an organic material known as Europium tetrakis (dibenzoylmethide) triethylammonium (EuD4TEA), which is a potential candidate for application as a damage sensor and could be made into a wireless sensor with the addition of microchip, antenna, and electronics. Preliminary results on the synthesis and characterization of this material are presented.

Carbon materials-functionalized tin dioxide nanoparticles toward robust, high-performance nitrogen dioxide gas sensor.

PubMed

Zhang, Rui; Liu, Xiupeng; Zhou, Tingting; Wang, Lili; Zhang, Tong

2018-08-15

Carbon (C) materials, which process excellent electrical conductivity and high carrier mobility, are promising sensing materials as active units for gas sensors. However, structural agglomeration caused by chemical processes results in a small resistance change and low sensing response. To address the above issues, structure-derived carbon-coated tin dioxide (SnO 2 ) nanoparticles having distinct core-shell morphology with a 3D net-like structure and highly uniform size are prepared by careful synthesis and fine structural design. The optimum carbon-coated SnO 2 nanoparticles (SnO 2 /C)-based gas sensor exhibits a low working temperature, excellent selectivity and fast response-recovery properties. In addition, the SnO 2 /C-based gas sensor can maintain a sensitivity to nitrogen dioxide (NO 2 ) of 3 after being cycled 4 times at 140 °C for, suggesting its good long-term stability. The structural integrity, good synergistic properties, and high gas-sensing performance of SnO 2 /C render it a promising sensing material for advanced gas sensors. Copyright © 2018 Elsevier Inc. All rights reserved.

Analysis of the detection materials as resonant pads for attaching the measuring arm of the interferometer when sensing mechanical vibrations

NASA Astrophysics Data System (ADS)

Nedoma, Jan; Fajkus, Marcel; Martinek, Radek; Zboril, Ondrej; Bednarek, Lukas; Novak, Martin; Witas, Karel; Vasinek, Vladimir

2017-05-01

Fiber-optic sensors (FOS), today among the most widespread measuring sensors and during various types of measuring, are irreplaceable. Among the distinctive features include immunity to electromagnetic interference, passivity regarding power supply and high sensitivity. One of the representatives FOS is the interferometric sensors working on the principle of interference of light. Authors of this article focused on the analysis of the detection material as resonant pads for attaching the measuring arm of the interferometer when sensing mechanical vibrations (low frequencies). A typical example is the use of interferometer sensors in automobile traffic while sensing a vibration response from the roadway while passing the cars. For analysis was used sensor with Mach-Zehnder interferometer. Defined were different detection materials about different size and thickness. We analyzed the influence on the sensitivity (amplitude response) of the interferometer. Based on the results we have defined the best material for sensing mechanical vibrations. The signal was processed by applications created in LabView development environment. The results were verified by repeated testing in laboratory conditions.

[Spectral characteristics of refractive index based on nanocoated optical fiber F-P sensor].

PubMed

Jiang, Ming-Shun; Li, Qiu-Shun; Sui, Qing-Mei; Jia, Lei; Peng, Peng

2013-01-01

An optical fiber Fabry-Perot (F-P) interferometer end surface was modified using layer-by-layer assembly and chemical covalent cross linking method, and the refractive index (RI) response characteristics of coated optical fiber F-P sensor were experimentally studied. Poly diallyldimethylammonium chloride (PDDA) and sodium polystyrene sulfonate (PSS) were chosen as nano-film materials. With the numbers of layers increasing, the reflection spectral contrast of optical fiber F-P sensor presents from high to low, then to high regularity. And the reflection spectral contrast has good temperature stability. The reflection spectra of the optical F-P sensor coated with 20 bilayers for a series of concentration of sucrose and inorganic solution were measured. Experimental results show that the inflection point extends from 1.457 to 1.462 3, and the reflection spectral contrast sensitivity to low RI material and high RI material is 24.53 and 3.60 dB x RI(-1), respectively, with good linearity. The results demonstrate that the functional coated optical F-P sensor provides a new method for biology and chemical material test.

Phenol-Formaldehyde Resin for Optical-Chemical Temperature Sensing.

PubMed

Claucherty, Steven; Sakaue, Hirotaka

2018-05-30

The application of phenol-formaldehyde (PF) resin as an optical temperature sensor is investigated. Recent developments in optical luminescent sensors allow for global measurements to be made over the surface of a test article, extending beyond conventional point measurements. Global temperature distributions are particularly helpful when validating computational models or when mapping temperature over complex geometries, and can be used to calculate surface heat flux values. Temperature-sensitive paint (TSP) is a novel chemical approach to obtaining these global temperature measurements, but there are still challenges to overcome to make it a reliable tool. A sensor with a wide range of temperature sensitivity is desired to provide the maximum amount of utility, especially for tests spanning large temperature gradients. Naturally luminescent materials such as PF resin provide an attractive alternative to chemical sensor coatings, and PF resin is studied for this reason. Static tests of different PF resin samples are conducted using two binder materials to strengthen the material: cloth and paper. The material shows temperature sensitivities up to -0.8%/K, demonstrating the usefulness of PF resin as a temperature sensor.

Modelling of chemical degradation of blended cement-based materials by leaching cycles with Callovo-Oxfordian porewater

NASA Astrophysics Data System (ADS)

Olmeda, Javier; Henocq, Pierre; Giffaut, Eric; Grivé, Mireia

2017-06-01

The present work describes a thermodynamic model based on pore water replacement cycles to simulate the chemical evolution of blended cement (BFS + FA) by interaction with external Callovo-Oxfordian (COx) pore water. In the framework of the radioactive waste management, the characterization of the radionuclide behaviour (solubility/speciation, adsorption) in cementitious materials needs to be done for several chemical degradation states (I to IV). In particular, in the context of the deep geological radioactive waste disposal project (Cigéo), cement-based materials will be chemically evolved with time in contact with the host-rock (COx formation). The objective of this study is to provide an equilibrium solution composition for each degradation state for a CEM-V cement-based material to support the adsorption and diffusion experiments reproducing any state of degradation. Calculations have been performed at 25 °C using the geochemical code PhreeqC and an up-to-date thermodynamic database (ThermoChimie v.9.0.b) coupled to SIT approach for ionic strength correction. The model replicates experimental data with accuracy. The approach followed in this study eases the analysis of the chemical evolution in both aqueous and solid phase to obtain a fast assessment of the geochemical effects associated to an external water intrusion of variable composition on concrete structures.

Method and apparatus for measuring surface changes, in porous materials, using multiple differently-configured acoustic sensors

DOEpatents

Hietala, Susan Leslie; Hietala, Vincent Mark; Tigges, Chris Phillip

2001-01-01

A method and apparatus for measuring surface changes, such as mass uptake at various pressures, in a thin-film material, in particular porous membranes, using multiple differently-configured acoustic sensors.

Characterization of cement-based materials using a reusable piezoelectric impedance-based sensor

NASA Astrophysics Data System (ADS)

Tawie, R.; Lee, H. K.

2011-08-01

This paper proposes a reusable sensor, which employs a piezoceramic (PZT) plate as an active sensing transducer, for non-destructive monitoring of cement-based materials based on the electromechanical impedance (EMI) sensing technique. The advantage of the sensor design is that the PZT can be easily removed from the set-up and re-used for repetitive tests. The applicability of the sensor was demonstrated for monitoring of the setting of cement mortar. EMI measurements were performed using an impedance analyzer and the transformation of the specimen from the plastic to solid state was monitored by automatically measuring the changes in the PZT conductance spectra with respect to curing time using the root mean square deviation (RMSD) algorithm. In another experiment, drying-induced moisture loss of a hardened mortar specimen at saturated surface dry (SSD) condition was measured, and monitored using the reusable sensor to establish a correlation between the RMSD values and moisture loss rate. The reusable sensor was also demonstrated for detecting progressive damages imparted on a mortar specimen attached with the sensor under several loading levels before allowing it to load to failure. Overall, the reusable sensor is an effective and efficient monitoring device that could possibly be used for field application in characterization of cement-based materials.

Universal penetration test apparatus with fluid penetration sensor

DOEpatents

Johnson, Phillip W.; Stampfer, Joseph F.; Bradley, Orvil D.

1999-01-01

A universal penetration test apparatus for measuring resistance of a material to a challenge fluid. The apparatus includes a pad saturated with the challenge fluid. The apparatus includes a compression assembly for compressing the material between the pad and a compression member. The apparatus also includes a sensor mechanism for automatically detecting when the challenge fluid penetrates the material.

Composite material for optical oxygen sensor

NASA Astrophysics Data System (ADS)

Antropov, A. P.; Ragutkin, A. V.; Melnikov, P. V.; Luchnikov, P. A.; Zaitsev, N. K.

2018-01-01

A new composite material for use in optical molecular oxygen sensors is proposed. The absence of pores on the surface of the material avoids microbiological fouling and concomitant deterioration of the characteristics with time, and the presence of the mesoporous phase results in a linear calibration and acceptable response times, even for layers that are significant in thickness.

Development of an In-Situ Decommissioning Sensor Network Test Bed for Structural Condition Monitoring - 12156

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

Zeigler, Kristine E.; Ferguson, Blythe A.

2012-07-01

The Savannah River National Laboratory (SRNL) has established an In Situ Decommissioning (ISD) Sensor Network Test Bed, a unique, small scale, configurable environment, for the assessment of prospective sensors on actual ISD system material, at minimal cost. The Department of Energy (DOE) is presently implementing permanent entombment of contaminated, large nuclear structures via ISD. The ISD end state consists of a grout-filled concrete civil structure within the concrete frame of the original building. Validation of ISD system performance models and verification of actual system conditions can be achieved through the development a system of sensors to monitor the materials andmore » condition of the structure. The ISD Sensor Network Test Bed has been designed and deployed to addresses the DOE-Environmental Management Technology Need to develop a remote monitoring system to determine and verify ISD system performance. Commercial off-the-shelf sensors have been installed on concrete blocks taken from walls of the P Reactor Building at the Savannah River Site. Deployment of this low-cost structural monitoring system provides hands-on experience with sensor networks. The initial sensor system consists of groutable thermistors for temperature and moisture monitoring, strain gauges for crack growth monitoring, tilt-meters for settlement monitoring, and a communication system for data collection. Baseline data and lessons learned from system design and installation and initial field testing will be utilized for future ISD sensor network development and deployment. The Sensor Network Test Bed at SRNL uses COTS sensors on concrete blocks from the outer wall of the P Reactor Building to measure conditions expected to occur in ISD structures. Knowledge and lessons learned gained from installation, testing, and monitoring of the equipment will be applied to sensor installation in a meso-scale test bed at FIU and in future ISD structures. The initial data collected from the sensors installed on the P Reactor Building blocks define the baseline materials condition of the P Reactor ISD external concrete structure. Continued monitoring of the blocks will enable evaluation of the effects of aging on the P Reactor ISD structure. The collected data will support validation of the material degradation model and assessment of the condition of the ISD structure over time. The following are recommendations for continued development of the ISD Sensor Network Test Bed: - Establish a long-term monitoring program using the concrete blocks with existing sensor and/or additional sensors for trending the concrete materials and structural condition; - Continue development of a stand-alone test bed sensor system that is self-powered and provides wireless transmission of data to a user-accessible dashboard; - Develop and implement periodic NDE/DE characterization of the concrete blocks to provide verification and validation for the measurements obtained through the sensor system and concrete degradation model(s). (authors)« less

Optical temperature sensor using thermochromic semiconductors

DOEpatents

Kronberg, James W.

1998-01-01

An optical temperature measuring device utilizes thermochromic semiconductors which vary in color in response to changes in temperature. The thermochromic material is sealed in a glass matrix which allows the temperature sensor to detect high temperatures without breakdown. Cuprous oxide and cadmium sulfide are among the semiconductor materials which provide the best results. The changes in color may be detected visually using a sensor chip and an accompanying color card.

Optical temperature sensor using thermochromic semiconductors

DOEpatents

Kronberg, J.W.

1998-06-30

An optical temperature measuring device utilizes thermochromic semiconductors which vary in color in response to changes in temperature. The thermochromic material is sealed in a glass matrix which allows the temperature sensor to detect high temperatures without breakdown. Cuprous oxide and cadmium sulfide are among the semiconductor materials which provide the best results. The changes in color may be detected visually using a sensor chip and an accompanying color card. 8 figs.

Magnetoresistive flux focusing eddy current flaw detection

NASA Technical Reports Server (NTRS)

Wincheski, Russell A. (Inventor); Simpson, John W. (Inventor); Namkung, Min (Inventor)

2005-01-01

A giant magnetoresistive flux focusing eddy current device effectively detects deep flaws in thick multilayer conductive materials. The probe uses an excitation coil to induce eddy currents in conducting material perpendicularly oriented to the coil's longitudinal axis. A giant magnetoresistive (GMR) sensor, surrounded by the excitation coil, is used to detect generated fields. Between the excitation coil and GMR sensor is a highly permeable flux focusing lens which magnetically separates the GMR sensor and excitation coil and produces high flux density at the outer edge of the GMR sensor. The use of feedback inside the flux focusing lens enables complete cancellation of the leakage fields at the GMR sensor location and biasing of the GMR sensor to a location of high magnetic field sensitivity. In an alternate embodiment, a permanent magnet is positioned adjacent to the GMR sensor to accomplish the biasing. Experimental results have demonstrated identification of flaws up to 1 cm deep in aluminum alloy structures. To detect deep flaws about circular fasteners or inhomogeneities in thick multilayer conductive materials, the device is mounted in a hand-held rotating probe assembly that is connected to a computer for system control, data acquisition, processing and storage.

Optical fiber sensors based on novel polyimide for humidity monitoring of building materials

NASA Astrophysics Data System (ADS)

Chai, Jing; Liu, Qi; Liu, Jinxuan; Zhang, Dingding

2018-03-01

This paper presents novel preparation methods of polyimide and coupling agent, coated on the fiber Bragg grating (FBG) sensor for monitoring relative humidity (RH). The sensing mechanism that the volume change of the moisture-sensitive polyimide induces the shift of the Bragg wavelength of FBG is used in the RH sensor. The performance of the polymer-coated RH sensor was evaluated under laboratory conditions of temperature over a range of values (20.0-80.0 °C) and humidity over a range of RH values (25.0-95.0%). The time response and RH sensitivity of the sensor based on novel polyimide and coupling agent was improved, compared to the previous. A new packaged RH sensor was designed, which was used in detecting the moisture diffusion and evolutions inside of sample made of building materials which exposed to a controlled environment in the lab after casting. Relative humidity inside of sample with time was 100% in the first phase of vapor-saturated, slowly reduced in the latter phase. The results indicate the RH sensor developed provides a feasible method to detect the influence of environment on moisture inside the material in the drying process.

Magnetoresistive Flux Focusing Eddy Current Flaw Detection

NASA Technical Reports Server (NTRS)

Wincheski, Russell A. (Inventor); Namkung, Min (Inventor); Simpson, John W. (Inventor)

2005-01-01

A giant magnetoresistive flux focusing eddy current device effectively detects deep flaws in thick multilayer conductive materials. The probe uses an excitation coil to induce eddy currents in conducting material perpendicularly oriented to the coil s longitudinal axis. A giant magnetoresistive (GMR) sensor, surrounded by the excitation coil, is used to detect generated fields. Between the excitation coil and GMR sensor is a highly permeable flux focusing lens which magnetically separates the GMR sensor and excitation coil and produces high flux density at the outer edge of the GMR sensor. The use of feedback inside the flux focusing lens enables complete cancellation of the leakage fields at the GMR sensor location and biasing of the GMR sensor to a location of high magnetic field sensitivity. In an alternate embodiment, a permanent magnet is positioned adjacent to the GMR sensor to accomplish the biasing. Experimental results have demonstrated identification of flaws up to 1 cm deep in aluminum alloy structures. To detect deep flaws about circular fasteners or inhomogeneities in thick multi-layer conductive materials, the device is mounted in a hand-held rotating probe assembly that is connected to a computer for system control, data acquisition, processing and storage.

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.

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.

A Review on Surface Stress-Based Miniaturized Piezoresistive SU-8 Polymeric Cantilever Sensors

NASA Astrophysics Data System (ADS)

Mathew, Ribu; Ravi Sankar, A.

2018-06-01

In the last decade, microelectromechanical systems (MEMS) SU-8 polymeric cantilevers with piezoresistive readout combined with the advances in molecular recognition techniques have found versatile applications, especially in the field of chemical and biological sensing. Compared to conventional solid-state semiconductor-based piezoresistive cantilever sensors, SU-8 polymeric cantilevers have advantages in terms of better sensitivity along with reduced material and fabrication cost. In recent times, numerous researchers have investigated their potential as a sensing platform due to high performance-to-cost ratio of SU-8 polymer-based cantilever sensors. In this article, we critically review the design, fabrication, and performance aspects of surface stress-based piezoresistive SU-8 polymeric cantilever sensors. The evolution of surface stress-based piezoresistive cantilever sensors from solid-state semiconductor materials to polymers, especially SU-8 polymer, is discussed in detail. Theoretical principles of surface stress generation and their application in cantilever sensing technology are also devised. Variants of SU-8 polymeric cantilevers with different composition of materials in cantilever stacks are explained. Furthermore, the interdependence of the material selection, geometrical design parameters, and fabrication process of piezoresistive SU-8 polymeric cantilever sensors and their cumulative impact on the sensor response are also explained in detail. In addition to the design-, fabrication-, and performance-related factors, this article also describes various challenges in engineering SU-8 polymeric cantilevers as a universal sensing platform such as temperature and moisture vulnerability. This review article would serve as a guideline for researchers to understand specifics and functionality of surface stress-based piezoresistive SU-8 cantilever sensors.[Figure not available: see fulltext.

Woven electrochemical fabric-based test sensors (WEFTS): a new class of multiplexed electrochemical sensors.

PubMed

Choudhary, Tripurari; Rajamanickam, G P; Dendukuri, Dhananjaya

2015-05-07

We present textile weaving as a new technique for the manufacture of miniature electrochemical sensors with significant advantages over current fabrication techniques. Biocompatible silk yarn is used as the material for fabrication instead of plastics and ceramics used in commercial sensors. Silk yarns are coated with conducting inks and reagents before being handloom-woven as electrodes into patches of fabric to create arrays of sensors, which are then laminated, cut and packaged into individual sensors. Unlike the conventionally used screen-printing, which results in wastage of reagents, yarn coating uses only as much reagent and ink as required. Hydrophilic and hydrophobic yarns are used for patterning so that sample flow is restricted to a small area of the sensor. This simple fluidic control is achieved with readily available materials. We have fabricated and validated individual sensors for glucose and hemoglobin and a multiplexed sensor, which can detect both analytes. Chronoamperometry and differential pulse voltammetry (DPV) were used to detect glucose and hemoglobin, respectively. Industrial quantities of these sensors can be fabricated at distributed locations in the developing world using existing skills and manufacturing facilities. We believe such sensors could find applications in the emerging area of wearable sensors for chemical testing.

Hollow polycaprolactone composite fibers for controlled magnetic responsive antifungal drug release.

PubMed

Wang, Baolin; Zheng, Hongxia; Chang, Ming-Wei; Ahmad, Zeeshan; Li, Jing-Song

2016-09-01

Hollow magnetic fibers for trigger based drug release were synthesized using one-step co-axial electrospinning (COX-ES). This was achieved by encapsulating the antifungal active 'ketoconazole' (KCZ) and iron oxide (Fe3O4) nanoparticles (NPs) in composite form within the core shell polymeric matrix material (polycaprolactone, PCL) during the COX-ES process. Dimethyl silicone oil was used as the inner core (liquid) of co-flowing solutions, which subsequently perfused out of the two-phase electrospun microstructures to form hollow fibers. Resulting drug-loaded magnetic hollow fibers were characterized using optical microscopy, scanning electron microscopy and Fourier Transform Infra-Red. The tensile strength and magnetization properties of composite fibers were also assessed. KCZ drug concentration in electrospinning solutions strongly influenced resulting fiber morphology, drug loading efficiency and release. Expedited drug release during a slow-sustained phase was demonstrated through the application of an auxiliary magnetic field. Variations in tensile strength (∼1.3-6.3MPa) were due to composite fiber components compromising polymer chain integrity. In-vitro cell studies (using human cervical carcinoma cell lines) demonstrated fiber biocompatibility. The present study demonstrates the potential application of magnetic hollow fibers for controlled treatment of fungal infections and antimicrobial indications. Copyright © 2016 Elsevier B.V. All rights reserved.

Structure Evolution and Multiferroic Properties in Cobalt Doped Bi4NdTi3Fe1-xCoxO15-Bi3NdTi2Fe1-xCoxO12-δ Intergrowth Aurivillius Compounds

PubMed Central

Zhang, D. L.; Huang, W. C.; Chen, Z. W.; Zhao, W. B.; Feng, L.; Li, M.; Yin, Y. W.; Dong, S. N.; Li, X. G.

2017-01-01

Here, we report the structure evolution, magnetic and ferroelectric properties in Co-doped 4- and 3-layered intergrowth Aurivillius compounds Bi4NdTi3Fe1-xCoxO15-Bi3NdTi2Fe1-xCoxO12-δ. The compounds suffer a structure evolution from the parent 4-layered phase (Bi4NdTi3FeO15) to 3-layered phase (Bi3NdTi2CoO12-δ) with increasing cobalt doping level from 0 to 1. Meanwhile the remanent magnetization and polarization show opposite variation tendencies against the doping level, and the sample with x = 0.3 has the largest remanent magnetization and the smallest polarization. It is believed that the Co concentration dependent magnetic properties are related to the population of the Fe3+ -O-Co3+ bonds, while the suppressed ferroelectric polarization is due to the enhanced leakage current caused by the increasing Co concentration. Furthermore, the samples (x = 0.1–0.7) with ferromagnetism show magnetoelectric coupling effects at room temperature. The results indicate that it is an effective method to create new multiferroic materials through modifying natural superlattices. PMID:28272495

Resistive Oxygen Gas Sensors for Harsh Environments

PubMed Central

Moos, Ralf; Izu, Noriya; Rettig, Frank; Reiß, Sebastian; Shin, Woosuck; Matsubara, Ichiro

2011-01-01

Resistive oxygen sensors are an inexpensive alternative to the classical potentiometric zirconia oxygen sensor, especially for use in harsh environments and at temperatures of several hundred °C or even higher. This device-oriented paper gives a historical overview on the development of these sensor materials. It focuses especially on approaches to obtain a temperature independent behavior. It is shown that although in the past 40 years there have always been several research groups working concurrently with resistive oxygen sensors, novel ideas continue to emerge today with respect to improvements of the sensor response time, the temperature dependence, the long-term stability or the manufacture of the devices themselves using novel techniques for the sensitive films. Materials that are the focus of this review are metal oxides; especially titania, titanates, and ceria-based formulations. PMID:22163805

Rare Earth Optical Temperature Sensor

NASA Technical Reports Server (NTRS)

Chubb, Donald L.; Wolford, David S.

2000-01-01

A new optical temperature sensor suitable for high temperatures (greater than 1700 K) and harsh environments is introduced. The key component of the sensor is the rare earth material contained at the end of a sensor that is in contact with the sample being measured. The measured narrow wavelength band emission from the rare earth is used to deduce the sample temperature. A simplified relation between the temperature and measured radiation was verified experimentally. The upper temperature limit of the sensor is determined by material limits to be approximately 2000 C. The lower limit, determined by the minimum detectable radiation, is found to be approximately 700 K. At high temperatures 1 K resolution is predicted. Also, millisecond response times are calculated.

Omega Design and FEA Based Coriolis Mass Flow Sensor (CMFS) Analysis Using Titanium Material

NASA Astrophysics Data System (ADS)

Patil, Pravin P.; Kumar, Ashwani; Ahmad, Faraz

2018-02-01

The main highlight of this research work is evaluation of resonant frequency for titanium omega type coriolis mass flow sensor. Coriolis mass flow sensor is used for measuring direct mass flow in pipe useful for various industrial applications. It works on the principle of Coriolis effect. Finite Element Analysis (FEA) simulation of omega flow sensor was performed using Ansys 14.5 and Solid Edge, Pro-E was used for modelling of omega tube. Titanium was selected as omega tube material. Experimental setup was prepared for omega tube coriolis flow sensor for performing different test. Experimental setup was used for investigation of different parameters effect on CMFS and validation of simulation results.

Fabrication of taste sensor for education

NASA Astrophysics Data System (ADS)

Wu, Xiao; Tahara, Yusuke; Toko, Kiyoshi; Kuriyaki, Hisao

2017-03-01

In order to solve the unconcern to usefulness of learning science among high school students in Japan, we developed a simple fabricated taste sensor with sensitivity and selectivity to each taste quality, which can be applied in science class. A commercialized Teflon membrane was used as the polymer membrane holding lipids. In addition, a non-adhesive method is considered to combine the membrane and the sensor electrode using a plastic cap which is easily accessible. The taste sensor for education fabricated in this way showed a good selectivity and sensitivity. By adjusting the composition of trioctylmethylammonium chloride (TOMA) and phosphoric acid di(2-ethylhexyl) ester (PAEE) included in lipid solution, we improved the selectivity of this simple taste sensor to saltiness and sourness. To verify this taste sensor as a useful science teaching material for science class, we applied this taste sensor into a science class for university students. By comparing the results between the sensory test and the sensor response, humans taste showed the same tendency just as the sensor response, which proved the sensor as a useful teaching material for science class.

Open Circuit Resonant Sensors for Composite Damage Detection and Diagnosis

NASA Technical Reports Server (NTRS)

Mielnik, John J., Jr.

2011-01-01

Under the Integrated Vehicle Health Management (IVHM) program work was begun to investigate the feasibility of sensor systems for detecting and diagnosing damage to aircraft composite structures and materials. Specific interest for this study was in damage initiated by environmental storm hazards and the direct effect of lightning strikes on the material structures of a composite aircraft in flight. A series of open circuit resonant sensors was designed, fabricated, characterized, and determined to be a potentially viable means for damage detection and diagnosis of composite materials. The results of this research and development effort are documented in this report.

Gas Permeable Chemochromic Compositions for Hydrogen Sensing

NASA Technical Reports Server (NTRS)

Mohajeri, Nahid (Inventor); Muradov, Nazim (Inventor); Tabatabaie-Raissi, Ali (Inventor); Bokerman, Gary (Inventor)

2013-01-01

A (H2) sensor composition includes a gas permeable matrix material intermixed and encapsulating at least one chemochromic pigment. The chemochromic pigment produces a detectable change in color of the overall sensor composition in the presence of H2 gas. The matrix material provides high H2 permeability, which permits fast permeation of H2 gas. In one embodiment, the chemochromic pigment comprises PdO/TiO2. The sensor can be embodied as a two layer structure with the gas permeable matrix material intermixed with the chemochromic pigment in one layer and a second layer which provides a support or overcoat layer.

Aluminum-thin-film packaged fiber Bragg grating probes for monitoring the maximum tensile strain of composite materials.

PubMed

Im, Jooeun; Kim, Mihyun; Choi, Ki-Sun; Hwang, Tae-Kyung; Kwon, Il-Bum

2014-06-10

In this paper, new fiber Bragg grating (FBG) sensor probes are designed to intermittently detect the maximum tensile strain of composite materials, so as to evaluate the structural health status. This probe is fabricated by two thin Al films bonded to an FBG optical fiber and two supporting brackets, which are fixed on the surface of composite materials. The residual strain of the Al packaged FBG sensor probe is induced by the strain of composite materials. This residual strain can indicate the maximum strain of composite materials. Two types of sensor probes are prepared-one is an FBG with 18 μm thick Al films, and the other is an FBG with 36 μm thick Al films-to compare the thickness effect on the detection sensitivity. These sensor probes are bonded on the surfaces of carbon fiber reinforced plastics composite specimens. In order to determine the strain sensitivity between the residual strain of the FBG sensor probe and the maximum strain of the composite specimen, tensile tests are performed by universal testing machine, under the loading-unloading test condition. The strain sensitivities of the probes, which have the Al thicknesses of 18 and 36 μm, are determined as 0.13 and 0.23, respectively.

Network of wireless gamma ray sensors for radiological detection and identification

NASA Astrophysics Data System (ADS)

Barzilov, A.; Womble, P.; Novikov, I.; Paschal, J.; Board, J.; Moss, K.

2007-04-01

The paper describes the design and development of a network of wireless gamma-ray sensors based on cell phone or WiFi technology. The system is intended for gamma-ray detection and automatic identification of radioactive isotopes and nuclear materials. The sensor is a gamma-ray spectrometer that uses wireless technology to distribute the results. A small-size sensor module contains a scintillation detector along with a small size data acquisition system, PDA, battery, and WiFi radio or a cell phone modem. The PDA with data acquisition and analysis software analyzes the accumulated spectrum on real-time basis and returns results to the screen reporting the isotopic composition and intensity of detected radiation source. The system has been programmed to mitigate false alarms from medical isotopes and naturally occurring radioactive materials. The decision-making software can be "trained" to indicate specific signatures of radiation sources like special nuclear materials. The sensor is supplied with GPS tracker coupling radiological information with geographical coordinates. The sensor is designed for easy use and rapid deployment in common wireless networks.

Schiff's Bases and Crown Ethers as Supramolecular Sensing Materials in the Construction of Potentiometric Membrane Sensors

PubMed Central

Faridbod, Farnoush; Ganjali, Mohammad Reza; Dinarvand, Rassoul; Norouzi, Parviz; Riahi, Siavash

2008-01-01

Ionophore incorporated PVC membrane sensors are well-established analytical tools routinely used for the selective and direct measurement of a wide variety of different ions in complex biological and environmental samples. Potentiometric sensors have some outstanding advantages including simple design and operation, wide linear dynamic range, relatively fast response and rational selectivity. The vital component of such plasticized PVC members is the ionophore involved, defining the selectivity of the electrodes' complex formation. Molecular recognition causes the formation of many different supramolecules. Different types of supramolecules, like calixarenes, cyclodextrins and podands, have been used as a sensing material in the construction of ion selective sensors. Schiff's bases and crown ethers, which feature prominently in supramolecular chemistry, can be used as sensing materials in the construction of potentiometric ion selective electrodes. Up to now, more than 200 potentiometric membrane sensors for cations and anions based on Schiff's bases and crown ethers have been reported. In this review cation binding and anion complexes will be described. Liquid membrane sensors based on Schiff's bases and crown ethers will then be discussed. PMID:27879786

A packaged, low-cost, robust optical fiber strain sensor based on small cladding fiber sandwiched within periodic polymer grating.

PubMed

Chiang, Chia-Chin; Li, Chein-Hsing

2014-06-02

In the present study, a novel packaged long-period fiber grating (PLPFG) strain sensor is first presented. The MEMS process was utilized to fabricate the packaged optical fiber strain sensor. The sensor structure consisted of etched optical fiber sandwiched between two layers of thick photoresist SU-8 3050 and then packaged with poly (dimethylsiloxane) (PDMS) polymer material to construct the PLPFG strain sensor. The PDMS packaging material was used to prevent the glue effect, wherein glue flows into the LPFG structure and reduces coupling strength, in the surface bonding process. Because the fiber grating was packaged with PDMS material, it was effectively protected and made robust. The resonance attenuation dip of PLPFG grows when it is loading. This study explored the size effect of the grating period and fiber diameter of PLPFG via tensile testing. The experimental results found that the best strain sensitivity of the PLPFG strain sensor was -0.0342 dB/με, and that an R2 value of 0.963 was reached.

Ultrasonic High-Temperature Sensors: Past Experiments and Prospects for Future Use

NASA Astrophysics Data System (ADS)

Laurie, M.; Magallon, D.; Rempe, J.; Wilkins, C.; Pierre, J.; Marquié, C.; Eymery, S.; Morice, R.

2010-09-01

Ultrasonic thermometry sensors (UTS) have been intensively studied in the past to measure temperatures from 2080 K to 3380 K. This sensor, which uses the temperature dependence of the acoustic velocity in materials, was developed for experiments in extreme environments. Its major advantages, which are (a) capability of measuring a temperature profile from multiple sensors on a single probe and (b) measurement near the sensor material melting point, can be of great interest when dealing with on-line monitoring of high-temperature safety tests. Ultrasonic techniques were successfully applied in several severe accident related experiments. With new developments of alternative materials, this instrument may be used in a wide range of experimental areas where robustness and compactness are required. Long-term irradiation experiments of nuclear fuel to extremely high burn-ups could benefit from this previous experience. After an overview of UTS technology, this article summarizes experimental work performed to improve the reliability of these sensors. The various designs, advantages, and drawbacks are outlined and future prospects for long-term high-temperature irradiation experiments are discussed.

Large strain detection of SRM composite shell based on fiber Bragg grating sensor

NASA Astrophysics Data System (ADS)

Zhang, Lei; Chang, Xinlong; Zhang, Youhong; Yang, Fan

2017-12-01

There may be more than 2% strain of carbon fiber composite material on solid rocket motor (SRM) in some extreme cases. A surface-bonded silica fiber Bragg grating (FBG) strain sensor coated by polymer is designed to detect the large strain of composite material. The strain transfer relation of the FBG large strain sensor is deduced, and the strain transfer mechanism is verified by finite element simulation. To calibrate the sensors, the tensile test is done by using the carbon fiber composite plate specimen attached to the designed strain sensor. The results show that the designed sensor can detect the strain more than 3%, the strain sensitivity is 0.0762 pm/μɛ, the resolution is 13.13μɛ, and the fitting degree of the wavelength-strain curve fitting function is 0.9988. The accuracy and linearity of the sensor can meet the engineering requirements.

A noncontact force sensor based on a fiber Bragg grating and its application for corrosion measurement.

PubMed

Pacheco, Clara J; Bruno, Antonio C

2013-08-29

A simple noncontact force sensor based on an optical fiber Bragg grating attached to a small magnet has been proposed and built. The sensor measures the force between the magnet and any ferromagnetic material placed within a few millimeters of the sensor. Maintaining the sensor at a constant standoff distance, material loss due to corrosion increases the distance between the magnet and the corroded surface, which decreases the magnetic force. This will decrease the strain in the optical fiber shifting the reflected Bragg wavelength. The measured shift for the optical fiber used was 1.36 nm per Newton. Models were developed to optimize the magnet geometry for a specific sensor standoff distance and for particular corrosion pit depths. The sensor was able to detect corrosion pits on a fuel storage tank bottom with depths in the sub-millimeter range.

A Noncontact Force Sensor Based on a Fiber Bragg Grating and Its Application for Corrosion Measurement

PubMed Central

Pacheco, Clara J.; Bruno, Antonio C.

2013-01-01

A simple noncontact force sensor based on an optical fiber Bragg grating attached to a small magnet has been proposed and built. The sensor measures the force between the magnet and any ferromagnetic material placed within a few millimeters of the sensor. Maintaining the sensor at a constant standoff distance, material loss due to corrosion increases the distance between the magnet and the corroded surface, which decreases the magnetic force. This will decrease the strain in the optical fiber shifting the reflected Bragg wavelength. The measured shift for the optical fiber used was 1.36 nm per Newton. Models were developed to optimize the magnet geometry for a specific sensor standoff distance and for particular corrosion pit depths. The sensor was able to detect corrosion pits on a fuel storage tank bottom with depths in the sub-millimeter range. PMID:23995095

Advanced Layered Composite Polylaminate Electroactive Actuator and Sensor

NASA Technical Reports Server (NTRS)

Fox, Robert L. (Inventor); Hellbaum, Richard F. (Inventor); Copeland, Benjamin M., Jr. (Inventor); Bryant, Robert G. (Inventor)

2000-01-01

The present invention relates to the mounting of pre-stressed electroactive material in such a manner that large displacement actuators or sensors result. The invention comprises mounting the pre-stressed electroactive material to a support layer. This combination of a pre-stressed electroactive material and support layer may in turn be attached to a mounting surface. The pre-stressed electroactive material may be a ferroelectric, pyroelectric, piezoelectric, or magnetostrictive material. The size, stiffness, mass, and material of the support layer is selected to result in the electroactive device having dynamic response properties, environmental capability characteristics, and the required resilience optimized for a given application. The capacity to connect the support layer to a surface expands the arenas in which the prestressed electroactive device may be used. Application for which the invention may be used include actuators, sensors, or as a component in a pumps, switches, relays, pressure transducers and acoustic devices.

Development of New Sensing Materials Using Combinatorial and High-Throughput Experimentation

NASA Astrophysics Data System (ADS)

Potyrailo, Radislav A.; Mirsky, Vladimir M.

New sensors with improved performance characteristics are needed for applications as diverse as bedside continuous monitoring, tracking of environmental pollutants, monitoring of food and water quality, monitoring of chemical processes, and safety in industrial, consumer, and automotive settings. Typical requirements in sensor improvement are selectivity, long-term stability, sensitivity, response time, reversibility, and reproducibility. Design of new sensing materials is the important cornerstone in the effort to develop new sensors. Often, sensing materials are too complex to predict their performance quantitatively in the design stage. Thus, combinatorial and high-throughput experimentation methodologies provide an opportunity to generate new required data to discover new sensing materials and/or to optimize existing material compositions. The goal of this chapter is to provide an overview of the key concepts of experimental development of sensing materials using combinatorial and high-throughput experimentation tools, and to promote additional fruitful interactions between computational scientists and experimentalists.

Sensor devices comprising a metal-organic framework material and methods of making and using the same

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

Wang, Alan X.; Chang, Chih-hung; Kim, Ki-Joong

Disclosed herein are embodiments of sensor devices comprising a sensing component able to determine the presence of, detect, and/or quantify detectable species in a variety of environments and applications. The sensing components disclosed herein can comprise MOF materials, plasmonic nanomaterials, or combinations thereof. In an exemplary embodiment, light guides can be coupled with the sensing components described herein to provide sensor devices capable of increased NIR detection sensitivity in determining the presence of detectable species, such as gases and volatile organic compounds. In another exemplary embodiment, optical properties of the plasmonic nanomaterials combined with MOF materials can be monitored directlymore » to detect analyte species through their impact on external conditions surrounding the particle or as a result of charge transfer to and from the plasmonic material as a result of interactions with the plasmonic material and/or the MOF material.« less

Universal penetration test apparatus with fluid penetration sensor

DOEpatents

Johnson, P.W.; Stampfer, J.F.; Bradley, O.D.

1999-02-02

A universal penetration test apparatus is described for measuring resistance of a material to a challenge fluid. The apparatus includes a pad saturated with the challenge fluid. The apparatus includes a compression assembly for compressing the material between the pad and a compression member. The apparatus also includes a sensor mechanism for automatically detecting when the challenge fluid penetrates the material. 23 figs.

Wireless sensor for detecting explosive material

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

Lamberti, Vincent E; Howell, Jr., Layton N; Mee, David K

Disclosed is a sensor for detecting explosive devices. The sensor includes a ferromagnetic metal and a molecular recognition reagent coupled to the ferromagnetic metal. The molecular recognition reagent is operable to expand upon absorption of vapor from an explosive material such that the molecular recognition reagent changes a tensile stress upon the ferromagnetic metal. The explosive device is detected based on changes in the magnetic switching characteristics of the ferromagnetic metal caused by the tensile stress.

Ammonia Optical Sensing by Microring Resonators

PubMed Central

Passaro, Vittorio M. N.; Dell'Olio, Francesco; De Leonardis, Francesco

2007-01-01

A very compact (device area around 40 μm2) optical ammonia sensor based on a microring resonator is presented in this work. Silicon-on-insulator technology is used in sensor design and a dye doped polymer is adopted as sensing material. The sensor exhibits a very good linearity and a minimum detectable refractive index shift of sensing material as low as 8×10-5, with a detection limit around 4 ‰. PMID:28903258

Mid-Infrared Optoelectronics: Materials and Devices. MIOMD-XII

DTIC Science & Technology

2014-10-01

current. An enhancement of the QEPAS signal can be achieved when two metallic tubes acting as a micro‐ resonator (mR) are added to the QTF sensor ...spectrophone configuration using a 5.8 mm long micro‐ resonator with an inner diameter of 0.80 mm [3]. In order to test and validate the developed QEPAS sensor ...materials, photodetectors, sensors and applications have been discussed in other sessions. The papers were submitted by researchers representing 107

Upconverting nanoparticles for optimizing scintillator based detection systems

DOEpatents

Kross, Brian; McKisson, John E; McKisson, John; Weisenberger, Andrew; Xi, Wenze; Zom, Carl

2013-09-17

An upconverting device for a scintillation detection system is provided. The detection system comprises a scintillator material, a sensor, a light transmission path between the scintillator material and the sensor, and a plurality of upconverting nanoparticles particles positioned in the light transmission path.

An embedded fibre optic sensor for impact damage detection in composite materials

NASA Astrophysics Data System (ADS)

Glossop, Neil David William

1989-09-01

A structurally embedded fiber optic damage detection sensor for composite materials is described. The system is designed specifically for the detection of barely visible damage resulting from low velocity impacts in Kevlar-epoxy laminates. By monitoring the light transmission properties of optical fiber embedded in the composite, it was shown that the integrity of the material can be accurately determined. The effect of several parameters on the sensitivity of the system was investigated, including the effect of the optical fiber orientation and depth of embedding within the composite. A novel surface was also developed for the optical fibers to ensure they will fracture at the requisite damage level. The influence of the optical fiber sensors on the tensile and compressive material properties and on the impact resistance of the laminate was also studied. Extensive experimental results from impact tests are reported and a numerical model of the impact event is presented which is able to predict and model the damage mechanism and sensor system. A new and powerful method of nondestructive evaluation for translucent composite materials based on image enhanced backlighting is also described.

Development of a polymer based fiberoptic magnetostrictive metal detector system.

PubMed

Hua, Wei Shu; Hooks, Joshua Rosenberg; Wu, Wen Jong; Wang, Wei Chih

2010-10-01

This paper presents a new metal detector using a fiberoptic magnetostriction sensor. The metal sensor uses a fiber-optic Mach-Zehnder interferometer with a newly developed ferromagnetic polymer as the magnetostrictive sensing material. This polymeric magnetostrictive fiberoptic metal sensor is simple to fabricate, small in size, and resistant to RF interference (which is common in typical electromagnetic type metal detectors). Metal detection is based on disruption of the magnetic flux density across the magnetostriction sensor. In this paper, characteristics of the material being sensed and magnetic properties of the ferromagnetic polymers will be discussed.

Development of an amperometric biosensor based on acetylcholine esterase covalently bound to a new support material.

PubMed

Khayyami, M; Pérez Pita, M T; Peña Garcia, N; Johansson, G; Danielsson, B; Larsson, P O

1998-01-01

A new type of amperometric biosensor based on immobilised acetylcholine esterase was designed and constructed. The enzyme was immobilised on a flow-through working electrode, which was prepared from reticulated vitreous carbon (RVC) or from a composite material consisting of RVC and superporous agarose. The sensor was operated in FIA mode using acetylthiocholine as a substrate. The sensor responded to inhibitors such as paraoxon-10(-9) mol was detected by the sensor in a non-optimised configuration. The practical lifetime of the sensor was at least 1 month.

Multifunctional 2D- Materials: Selenides and Halides

NASA Technical Reports Server (NTRS)

Singh, N. B.; Su, Ching Hua; Arnold, Brad; Choa, Fow-Sen; Bohorfous, Sara

2016-01-01

Material is the key component and controls the performance of the detectors, devices and sensors. The materials design, processing, growth and fabrication of bulk and nanocrystals and fabrication into devices and sensors involve multidisciplinary team of experts. This places a large burden on the cost of the novel materials development. Due to this reason there is a big thrust for the prediction of multifunctionality of materials before design and development. Up to some extent design can achieve certain properties. In multinary materials processing is also a big factor. In this presentation, examples of two classes of industrially important materials will be described.

Microbial BOD sensors based on Zr (IV)-loaded collagen fiber.

PubMed

Zhao, Lei; He, Li; Chen, Shujuan; Zou, Likou; Zhou, Kang; Ao, Xiaolin; Liu, Shuliang; Hu, Xinjie; Han, Guoquan

2017-03-01

Biochemical oxygen demand (BOD) sensors based on Zr (IV)-loaded collagen fiber (ZrCF), a novel material with great porous structure, were developed. This novel material shows adsorbability by microorganisms. Saccharomyces cerevisiae and Escherichia coli were used for the construction of BOD sensors. Factors affecting BOD sensor performance were examined. The ZrCF-based BOD sensor showed different sensitivities and linear response ranges with different biofilm densities. The amount of microorganisms strongly affected the performance of the BOD sensor. Poor permeability of previously reported immobilization carriers were greatly circumvented by ZrCF. The service life of the ZrCF-based BOD sensor was more than 42 days. The immobilized microorganisms can be stored for more than 6 months under 4°C in PB solution. There was good correlation between the results of the sensor method and the standard 5-day BOD method in the determination of pure organic substrates and real water samples. Copyright © 2016 Elsevier Inc. All rights reserved.

Design and test of a biosensor-based multisensorial system: a proof of concept study.

PubMed

Santonico, Marco; Pennazza, Giorgio; Grasso, Simone; D'Amico, Arnaldo; Bizzarri, Mariano

2013-12-04

Sensors are often organized in multidimensional systems or networks for particular applications. This is facilitated by the large improvements in the miniaturization process, power consumption reduction and data analysis techniques nowadays possible. Such sensors are frequently organized in multidimensional arrays oriented to the realization of artificial sensorial systems mimicking the mechanisms of human senses. Instruments that make use of these sensors are frequently employed in the fields of medicine and food science. Among them, the so-called electronic nose and tongue are becoming more and more popular. In this paper an innovative multisensorial system based on sensing materials of biological origin is illustrated. Anthocyanins are exploited here as chemical interactive materials for both quartz microbalance (QMB) transducers used as gas sensors and for electrodes used as liquid electrochemical sensors. The optical properties of anthocyanins are well established and widely used, but they have never been exploited as sensing materials for both gas and liquid sensors in non-optical applications. By using the same set of selected anthocyanins an integrated system has been realized, which includes a gas sensor array based on QMB and a sensor array for liquids made up of suitable Ion Sensitive Electrodes (ISEs). The arrays are also monitored from an optical point of view. This embedded system, is intended to mimic the working principles of the nose, tongue and eyes. We call this setup BIONOTE (for BIOsensor-based multisensorial system for mimicking NOse, Tongue and Eyes). The complete design, fabrication and calibration processes of the BIONOTE system are described herein, and a number of preliminary results are discussed. These results are relative to: (a) the characterization of the optical properties of the tested materials; (b) the performance of the whole system as gas sensor array with respect to ethanol, hexane and isopropyl alcohol detection (concentration range 0.1-7 ppm) and as a liquid sensor array (concentration range 73-98 μM).

Control of contaminants on sensors. Report 1: Interdirectorate working group on earth observation sensors

NASA Technical Reports Server (NTRS)

Hovis, W.; Smith, D.; Mcculloch, A.; Goldberg, I. L.; Ostrow, H.; Seidenberg, B.

1973-01-01

Examples of contamination of sensors from various sources during space missions are presented. Design precautions to provide access to optical surfaces and venting of outgassing products are recommended as methods for coping with contamination. The effects of the sensor materials on sensor contamination are analyzed. Actions to be taken during transportation, storage, and testing of sensors to avoid contamination are discussed.

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

Locating Sensors for Detecting Source-to-Target Patterns of Special Nuclear Material Smuggling: A Spatial Information Theoretic Approach

PubMed Central

Przybyla, Jay; Taylor, Jeffrey; Zhou, Xuesong

2010-01-01

In this paper, a spatial information-theoretic model is proposed to locate sensors for detecting source-to-target patterns of special nuclear material (SNM) smuggling. In order to ship the nuclear materials from a source location with SNM production to a target city, the smugglers must employ global and domestic logistics systems. This paper focuses on locating a limited set of fixed and mobile radiation sensors in a transportation network, with the intent to maximize the expected information gain and minimize the estimation error for the subsequent nuclear material detection stage. A Kalman filtering-based framework is adapted to assist the decision-maker in quantifying the network-wide information gain and SNM flow estimation accuracy. PMID:22163641

Active Control Technology at NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Antcliff, Richard R.; McGowan, Anna-Marie R.

2000-01-01

NASA Langley has a long history of attacking important technical Opportunities from a broad base of supporting disciplines. The research and development at Langley in this subject area range from the test tube to the test flight, The information covered here will range from the development of innovative new materials, sensors and actuators, to the incorporation of smart sensors and actuators in practical devices, to the optimization of the location of these devices, to, finally, a wide variety of applications of these devices utilizing Langley's facilities and expertise. Advanced materials are being developed for sensors and actuators, as well as polymers for integrating smart devices into composite structures. Contributions reside in three key areas: computational materials; advanced piezoelectric materials; and integrated composite structures.

Locating sensors for detecting source-to-target patterns of special nuclear material smuggling: a spatial information theoretic approach.

PubMed

Przybyla, Jay; Taylor, Jeffrey; Zhou, Xuesong

2010-01-01

In this paper, a spatial information-theoretic model is proposed to locate sensors for detecting source-to-target patterns of special nuclear material (SNM) smuggling. In order to ship the nuclear materials from a source location with SNM production to a target city, the smugglers must employ global and domestic logistics systems. This paper focuses on locating a limited set of fixed and mobile radiation sensors in a transportation network, with the intent to maximize the expected information gain and minimize the estimation error for the subsequent nuclear material detection stage. A Kalman filtering-based framework is adapted to assist the decision-maker in quantifying the network-wide information gain and SNM flow estimation accuracy.

Development and Application of Microfabricated Chemical Gas Sensors For Aerospace Applications

NASA Technical Reports Server (NTRS)

Hunter, G. W.; Neudeck, P. G.; Fralick, G.; Thomas, V.; Liu, C. C.; Wu, Q. H.; Sawayda, M. S.; Jin, A.; Hammond, J.; Makel, D.;

Rubbery electronics and sensors from intrinsically stretchable elastomeric composites of semiconductors and conductors

PubMed Central

Kim, Hae-Jin; Sim, Kyoseung; Thukral, Anish; Yu, Cunjiang

2017-01-01

A general strategy to impart mechanical stretchability to stretchable electronics involves engineering materials into special architectures to accommodate or eliminate the mechanical strain in nonstretchable electronic materials while stretched. We introduce an all solution–processed type of electronics and sensors that are rubbery and intrinsically stretchable as an outcome from all the elastomeric materials in percolated composite formats with P3HT-NFs [poly(3-hexylthiophene-2,5-diyl) nanofibrils] and AuNP-AgNW (Au nanoparticles with conformally coated silver nanowires) in PDMS (polydimethylsiloxane). The fabricated thin-film transistors retain their electrical performances by more than 55% upon 50% stretching and exhibit one of the highest P3HT-based field-effect mobilities of 1.4 cm2/V∙s, owing to crystallinity improvement. Rubbery sensors, which include strain, pressure, and temperature sensors, show reliable sensing capabilities and are exploited as smart skins that enable gesture translation for sign language alphabet and haptic sensing for robotics to illustrate one of the applications of the sensors. PMID:28913428

Incorporation of hydrogel as a sensing medium for recycle of sensing material in chemical sensors

NASA Astrophysics Data System (ADS)

Hwang, Yunjung; Park, Jeong Yong; Kwon, Oh Seok; Joo, Seokwon; Lee, Chang-Soo; Bae, Joonwon

2018-01-01

A hydrogel, produced with agarose extracted from seaweed, was introduced as a reusable medium in ultrasensitive sensors employing conducting polymer nanomaterials and aptamers. A basic dopamine (DA) sensor was constructed by placing a hydrogel, containing a sensing material composed of aptamer-linked carboxylated polypyrrole nanotubes (PPy-COOH NTs), onto a micropatterned gold electrode. The hydrogel provided a benign electrochemical environment, facilitated specific interactions between DA and the PPy-COOH NT sensing material, and simplified the retrieval of PPy-COOH NTs after detection. It was demonstrated that the agarose hydrogel was successfully employed as a sensing medium for detection of DA, providing a benign environment for the electrode type sensor. PPy-COOH NTs were recovered by simply heating the hydrogel in water. The hydrogel also afforded stable signal intensity after repeated use with a limit of detection of 1 nmol and a clear, stable signal up to 100 nmol DA. This work provides relevant information for future research on reusable or recyclable sensors.

Application of V2O5/WO3/TiO2 for Resistive-Type SO2 Sensors

PubMed Central

Izu, Noriya; Hagen, Gunter; Schönauer, Daniela; Röder-Roith, Ulla; Moos, Ralf

2011-01-01

A study on the application of V2O5/WO3/TiO2 (VWT) as the sensitive material for resistive-type SO2 sensor was conducted, based on the fact that VWT is a well-known catalyst material for good selective catalytic nitrogen oxide reduction with a proven excellent durability in exhaust gases. The sensors fabricated in this study are planar ones with interdigitated electrodes of Au or Pt. The vanadium content of the utilized VWT is 1.5 or 3.0 wt%. The resistance of VWT decreases with an increasing SO2 concentration in the range from 20 ppm to 5,000 ppm. The best sensor response to SO2 occurs at 400 °C using Au electrodes. The sensor response value is independent on the amount of added vanadium but dependent on the electrode materials at 400 °C. These results are discussed and a sensing mechanism is discussed. PMID:22163780

Metal-silica sol-gel materials

NASA Technical Reports Server (NTRS)

Stiegman, Albert E. (Inventor)

2002-01-01

The present invention relates to a single phase metal-silica sol-gel glass formed by the co-condensation of a transition metal with silicon atoms where the metal atoms are uniformly distributed within the sol-gel glass as individual metal centers. Any transition metal may be used in the sol-gel glasses. The present invention also relates to sensor materials where the sensor material is formed using the single phase metal-silica sol-gel glasses. The sensor materials may be in the form of a thin film or may be attached to an optical fiber. The present invention also relates to a method of sensing chemicals using the chemical sensors by monitoring the chromatic change of the metal-silica sol-gel glass when the chemical binds to the sensor. The present invention also relates to oxidation catalysts where a metal-silica sol-gel glass catalyzes the reaction. The present invention also relates to a method of performing oxidation reactions using the metal-silica sol-gel glasses. The present invention also relates to organopolymer metal-silica sol-gel composites where the pores of the metal-silica sol-gel glasses are filled with an organic polymer polymerized by the sol-gel glass.

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.

Optical and Electronic NOx Sensors for Applications in Mechatronics

PubMed Central

Di Franco, Cinzia; Elia, Angela; Spagnolo, Vincenzo; Scamarcio, Gaetano; Lugarà, Pietro Mario; Ieva, Eliana; Cioffi, Nicola; Torsi, Luisa; Bruno, Giovanni; Losurdo, Maria; Garcia, Michael A.; Wolter, Scott D.; Brown, April; Ricco, Mario

2009-01-01

Current production and emerging NOx sensors based on optical and nanomaterials technologies are reviewed. In view of their potential applications in mechatronics, we compared the performance of: i) Quantum cascade lasers (QCL) based photoacoustic (PA) systems; ii) gold nanoparticles as catalytically active materials in field-effect transistor (FET) sensors, and iii) functionalized III-V semiconductor based devices. QCL-based PA sensors for NOx show a detection limit in the sub part-per-million range and are characterized by high selectivity and compact set-up. Electrochemically synthesized gold-nanoparticle FET sensors are able to monitor NOx in a concentration range from 50 to 200 parts per million and are suitable for miniaturization. Porphyrin-functionalized III-V semiconductor materials can be used for the fabrication of a reliable NOx sensor platform characterized by high conductivity, corrosion resistance, and strong surface state coupling. PMID:22412315

Preclinical Performance Evaluation of Percutaneous Glucose Biosensors: Experimental Considerations and Recommendations.

PubMed

Soto, Robert J; Schoenfisch, Mark H

2015-06-17

The utility of continuous glucose monitoring devices remains limited by an obstinate foreign body response (FBR) that degrades the analytical performance of the in vivo sensor. A number of novel materials that resist or delay the FBR have been proposed as outer, tissue-contacting glucose sensor membranes as a strategy to improve sensor accuracy. Traditionally, researchers have examined the ability of a material to minimize the host response by assessing adsorbed cell morphology and tissue histology. However, these techniques do not adequately predict in vivo glucose sensor function, necessitating sensor performance evaluation in a relevant animal model prior to human testing. Herein, the effects of critical experimental parameters, including the animal model and data processing methods, on the reliability and usefulness of preclinical sensor performance data are considered. © 2015 Diabetes Technology Society.

Novel Flexible Wearable Sensor Materials and Signal Processing for Vital Sign and Human Activity Monitoring.

PubMed

Servati, Amir; Zou, Liang; Wang, Z Jane; Ko, Frank; Servati, Peyman

2017-07-13

Advances in flexible electronic materials and smart textile, along with broad availability of smart phones, cloud and wireless systems have empowered the wearable technologies for significant impact on future of digital and personalized healthcare as well as consumer electronics. However, challenges related to lack of accuracy, reliability, high power consumption, rigid or bulky form factor and difficulty in interpretation of data have limited their wide-scale application in these potential areas. As an important solution to these challenges, we present latest advances in novel flexible electronic materials and sensors that enable comfortable and conformable body interaction and potential for invisible integration within daily apparel. Advances in novel flexible materials and sensors are described for wearable monitoring of human vital signs including, body temperature, respiratory rate and heart rate, muscle movements and activity. We then present advances in signal processing focusing on motion and noise artifact removal, data mining and aspects of sensor fusion relevant to future clinical applications of wearable technology.

Novel Flexible Wearable Sensor Materials and Signal Processing for Vital Sign and Human Activity Monitoring

PubMed Central

Servati, Amir; Wang, Z. Jane; Ko, Frank; Servati, Peyman

2017-01-01

Advances in flexible electronic materials and smart textile, along with broad availability of smart phones, cloud and wireless systems have empowered the wearable technologies for significant impact on future of digital and personalized healthcare as well as consumer electronics. However, challenges related to lack of accuracy, reliability, high power consumption, rigid or bulky form factor and difficulty in interpretation of data have limited their wide-scale application in these potential areas. As an important solution to these challenges, we present latest advances in novel flexible electronic materials and sensors that enable comfortable and conformable body interaction and potential for invisible integration within daily apparel. Advances in novel flexible materials and sensors are described for wearable monitoring of human vital signs including, body temperature, respiratory rate and heart rate, muscle movements and activity. We then present advances in signal processing focusing on motion and noise artifact removal, data mining and aspects of sensor fusion relevant to future clinical applications of wearable technology. PMID:28703744

Investigation of Carbon-Polymer Structures with Embedded Fiber-Optic Bragg Gratings

NASA Technical Reports Server (NTRS)

Grant, Joseph; Kaul, R.; Taylor, S.; Myers, G.; Sharma, A.

2003-01-01

Several Bragg-grating sensors fabricated within the same optical fiber are buried within multiple-ply carbon-epoxy planar and cylindrical structures. Effect of different orientation of fiber-sensors with respect to carbon fibers in the composite structure is investigated. This is done for both fabric and uni-tape material samples. Response of planar structures to axial and transverse strain up to 1 millistrain is investigated with distributed Bragg-grating sensors. Material properties like Young's Modulus and Poisson ratio is measured. A comparison is made between response measured by sensors in different ply-layers and those bonded on the surface. The results from buried fiber- sensors do not completely agree with surface bonded conventional strain gauges. A plausible explanation is given for observed differences. The planar structures are subjected to impacts with energies up to 10 ft-lb. Effect of this impact on the material stiffness is also investigated with buried fiber-optic Bragg sensors. The strain response of such optical sensors is also measured for cylindrical carbon-epoxy composite structures. The sensors are buried within the walls of the cylinder as well as surface bonded in both the axial as well as hoop directions. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 1500 psi. This is done at both room temperature as well as cryogenic temperatures. The recorded response is compared with that from a conventional strain gauge.

The theory and design of piezoelectric/pyroelectric polymer film sensors for biomedical engineering applications.

PubMed

Brown, L F

1989-01-01

The unique properties of piezoelectric/pyroelectric polymers offer many new opportunities for biomedical engineering sensor applications. Since their discovery nearly 20 years ago, the polymer films have been used for many novel switching and sensor applications. Despite the prodigious exposure from many recent publications describing piezo film applications, methods of sensor fabrication and circuit interfacing still elude most engineers. This paper is presented as a tutorial guide to applying piezo polymers to biomedical engineering applications. A review of the fundamentals of piezoelectricity/pyroelectricity in piezo polymers is first presented. Their material properties are contrasted with piezoelectric ceramic materials. Some advantages and disadvantages of the films for biomedical sensors are discussed. Specific details on the fabrication of piezo film sensors are presented. Methods are described for forming, cutting, and mounting film sensors, and making lead connections. A brief discussion of equivalent circuit models for the design and simulation of piezoelectric/pyroelectric sensors is included, as well as common circuit interface techniques. Finally, several sources are recommended for further information on a variety of biomedical sensor applications.

Synthesis of Metal Oxide Nanomaterials for Chemical Sensors by Molecular Beam Epitaxy

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

Nandasiri, Manjula I.; Kuchibhatla, Satyanarayana V N T; Thevuthasan, Suntharampillai

2013-12-01

Since the industrial revolution, detection and monitoring of toxic matter, chemical wastes, and air pollutants has become an important environmental issue. Thus, it leads to the development of chemical sensors for various environmental applications. The recent disastrous oil spills over the near-surface of ocean due to the offshore drilling emphasize the use of chemical sensors for prevention and monitoring of the processes that might lead to these mishaps.1, 2 Chemical sensors operated on a simple principle that the sensing platform undergoes a detectable change when exposed to the target substance to be sensed. Among all the types of chemical sensors,more » solid state gas sensors have attracted a great deal of attention due to their advantages such as high sensitivity, greater selectivity, portability, high stability and low cost.3, 4 Especially, semiconducting metal oxides such as SnO2, TiO2, and WO3 have been widely used as the active sensing platforms in solid state gas sensors.5 For the enhanced properties of solid state gas sensors, finding new sensing materials or development of existing materials will be needed. Thus, nanostructured materials such as nanotubes,6-8 nanowires,9-11 nanorods,12-15 nanobelts,16, 17 and nano-scale thin films18-23 have been synthesized and studied for chemical sensing applications.« less

High accuracy electronic material level sensor

DOEpatents

McEwan, T.E.

1997-03-11

The High Accuracy Electronic Material Level Sensor (electronic dipstick) is a sensor based on time domain reflectometry (TDR) of very short electrical pulses. Pulses are propagated along a transmission line or guide wire that is partially immersed in the material being measured; a launcher plate is positioned at the beginning of the guide wire. Reflected pulses are produced at the material interface due to the change in dielectric constant. The time difference of the reflections at the launcher plate and at the material interface are used to determine the material level. Improved performance is obtained by the incorporation of: (1) a high accuracy time base that is referenced to a quartz crystal, (2) an ultrawideband directional sampler to allow operation without an interconnect cable between the electronics module and the guide wire, (3) constant fraction discriminators (CFDs) that allow accurate measurements regardless of material dielectric constants, and reduce or eliminate errors induced by triple-transit or ``ghost`` reflections on the interconnect cable. These improvements make the dipstick accurate to better than 0.1%. 4 figs.

High accuracy electronic material level sensor

DOEpatents

McEwan, Thomas E.

1997-01-01

The High Accuracy Electronic Material Level Sensor (electronic dipstick) is a sensor based on time domain reflectometry (TDR) of very short electrical pulses. Pulses are propagated along a transmission line or guide wire that is partially immersed in the material being measured; a launcher plate is positioned at the beginning of the guide wire. Reflected pulses are produced at the material interface due to the change in dielectric constant. The time difference of the reflections at the launcher plate and at the material interface are used to determine the material level. Improved performance is obtained by the incorporation of: 1) a high accuracy time base that is referenced to a quartz crystal, 2) an ultrawideband directional sampler to allow operation without an interconnect cable between the electronics module and the guide wire, 3) constant fraction discriminators (CFDs) that allow accurate measurements regardless of material dielectric constants, and reduce or eliminate errors induced by triple-transit or "ghost" reflections on the interconnect cable. These improvements make the dipstick accurate to better than 0.1%.

Elastomeric optical fiber sensors and method for detecting and measuring events occurring in elastic materials

DOEpatents

Muhs, Jeffrey D.; Capps, Gary J.; Smith, David B.; White, Clifford P.

1994-01-01

Fiber optic sensing means for the detection and measurement of events such as dynamic loadings imposed upon elastic materials including cementitious materials, elastomers, and animal body components and/or the attrition of such elastic materials are provided. One or more optical fibers each having a deformable core and cladding formed of an elastomeric material such as silicone rubber are embedded in the elastic material. Changes in light transmission through any of the optical fibers due the deformation of the optical fiber by the application of dynamic loads such as compression, tension, or bending loadings imposed on the elastic material or by the attrition of the elastic material such as by cracking, deterioration, aggregate break-up, and muscle, tendon, or organ atrophy provide a measurement of the dynamic loadings and attrition. The fiber optic sensors can be embedded in elastomers subject to dynamic loadings and attrition such as commonly used automobiles and in shoes for determining the amount and frequency of the dynamic loadings and the extent of attrition. The fiber optic sensors are also useable in cementitious material for determining the maturation thereof.

Design of interdigital spiral and concentric capacitive sensors for materials evaluation

NASA Astrophysics Data System (ADS)

Chen, Tianming; Bowler, Nicola

2013-01-01

This paper describes the design of two circular coplanar interdigital sensors with i) a spiral interdigital configuration and ii) a concentric interdigital configuration for the nondestructive evaluation of multilayered dielectric structures. A numerical model accounting for sensor geometry, test-piece geometry and real permittivity, and metal electrode thickness has been developed to calculate the capacitance of the sensors when in contact with a planar test-piece comprising up to four layers. Compared with a disk-and-ring coplanar capacitive sensor developed previously, the interdigital configurations are predicted to have higher signal-to-noise ratio and better accuracy in materials characterization. The disk-and-ring configuration, on the other hand, possesses advantages such as deeper penetration depth and better immunity to lift-off variations.

Temperature-programmed technique accompanied with high-throughput methodology for rapidly searching the optimal operating temperature of MOX gas sensors.

PubMed

Zhang, Guozhu; Xie, Changsheng; Zhang, Shunping; Zhao, Jianwei; Lei, Tao; Zeng, Dawen

2014-09-08

A combinatorial high-throughput temperature-programmed method to obtain the optimal operating temperature (OOT) of gas sensor materials is demonstrated here for the first time. A material library consisting of SnO2, ZnO, WO3, and In2O3 sensor films was fabricated by screen printing. Temperature-dependent conductivity curves were obtained by scanning this gas sensor library from 300 to 700 K in different atmospheres (dry air, formaldehyde, carbon monoxide, nitrogen dioxide, toluene and ammonia), giving the OOT of each sensor formulation as a function of the carrier and analyte gases. A comparative study of the temperature-programmed method and a conventional method showed good agreement in measured OOT.

Movement Intention Prediction to Find a New Exoskeleton Design with Light and Comfortable Materials

NASA Astrophysics Data System (ADS)

Plaza Torres, Ing. Mauricio; Fredy Bernal, Ing; Andrés Cifuentes, Ing.

2017-12-01

This paper presents a discussion about the design a novel exoskeleton and the implementation of superficial magnetic sensor and pressure sensor for find patterns and parameters in order to predicting the intention of movement for people with musculoskeletal system problem in lower limbs. The information is obtained through reading position and movement by magnetic and pressure sensor installed in different parts of the body. The advantage of this sensor is the location of the position reference of the every part of the body. Using the sensor in some parts of the body is possible to calculate the muscle contraction for the prediction of intended movement and to find a new design with light and comfortable materials.

Towards the effect of acoustic emission (AE) sensor positioning within AE signal parameters in sliding on bulk ultrafine-grained materials

NASA Astrophysics Data System (ADS)

Filippov, A. V.; Tarasov, S. Yu.; Podgornykh, O. A.; Chazov, P. A.; Shamarin, N. N.; Filippova, E. O.

2017-12-01

The effect of AE sensor positioning on the bulk ultrafine-grained materials used for sliding against steel ball has been investigated. Two versions of AE sensor positioning have been tested and showed the different attenuation levels. The experimentally obtained AE signal waveforms have been analyzed under the AE signal parameters such as a median frequency and AE energy. It was established that the AE sensor positioned on the sample supporting plate in the vicinity of the sample tested allowed redistribution of the signal energy from a low-frequency to high-frequency range as well as extending the median frequency range as compared to those obtained by mounting the sensor on the immobile sample holder.

Highly selective and sensitive trimethylamine gas sensor based on cobalt imidazolate framework material.

PubMed

Chen, Er-Xia; Fu, Hong-Ru; Lin, Rui; Tan, Yan-Xi; Zhang, Jian

2014-12-24

A cobalt imidazolate (im) framework material [Co(im)2]n was employed to use as a trimethylamine (TMA) gas sensor and the [Co(im)2]n sensor can be easily fabricated by using Ag-Pd interdigitated electrodes. Gas sensing measurement indicated that the [Co(im)2]n sensor shows excellent selectivity, high gas response and a low detection limit level of 2 ppm to TMA at 75 °C. The good selectivity and high response to TMA of the sensor based on [Co(im)2]n may be attributed to the weak interaction between the TMA molecules and the [Co(im)2]n framework. That may provide an ideal candidate for detecting freshness of fish and seafood.

Development and implementation of an automatic integration system for fibre optic sensors in the braiding process with the objective of online-monitoring of composite structures

NASA Astrophysics Data System (ADS)

Hufenbach, W.; Gude, M.; Czulak, A.; Kretschmann, Martin

2014-04-01

Increasing economic, political and ecological pressure leads to steadily rising percentage of modern processing and manufacturing processes for fibre reinforced polymers in industrial batch production. Component weights beneath a level achievable by classic construction materials, which lead to a reduced energy and cost balance during product lifetime, justify the higher fabrication costs. However, complex quality control and failure prediction slow down the substitution by composite materials. High-resolution fibre-optic sensors (FOS), due their low diameter, high measuring point density and simple handling, show a high applicability potential for an automated sensor-integration in manufacturing processes, and therefore the online monitoring of composite products manufactured in industrial scale. Integrated sensors can be used to monitor manufacturing processes, part tests as well as the component structure during product life cycle, which simplifies allows quality control during production and the optimization of single manufacturing processes.[1;2] Furthermore, detailed failure analyses lead to a enhanced understanding of failure processes appearing in composite materials. This leads to a lower wastrel number and products of a higher value and longer product life cycle, whereby costs, material and energy are saved. This work shows an automation approach for FOS-integration in the braiding process. For that purpose a braiding wheel has been supplemented with an appliance for automatic sensor application, which has been used to manufacture preforms of high-pressure composite vessels with FOS-networks integrated between the fibre layers. All following manufacturing processes (vacuum infiltration, curing) and component tests (quasi-static pressure test, programmed delamination) were monitored with the help of the integrated sensor networks. Keywords: SHM, high-pressure composite vessel, braiding, automated sensor integration, pressure test, quality control, optic-fibre sensors, Rayleigh, Luna Technologies

Development of a handheld widefield hyperspectral imaging (HSI) sensor for standoff detection of explosive, chemical, and narcotic residues

NASA Astrophysics Data System (ADS)

Nelson, Matthew P.; Basta, Andrew; Patil, Raju; Klueva, Oksana; Treado, Patrick J.

2013-05-01

The utility of Hyper Spectral Imaging (HSI) passive chemical detection employing wide field, standoff imaging continues to be advanced in detection applications. With a drive for reduced SWaP (Size, Weight, and Power), increased speed of detection and sensitivity, developing a handheld platform that is robust and user-friendly increases the detection capabilities of the end user. In addition, easy to use handheld detectors could improve the effectiveness of locating and identifying threats while reducing risks to the individual. ChemImage Sensor Systems (CISS) has developed the HSI Aperio™ sensor for real time, wide area surveillance and standoff detection of explosives, chemical threats, and narcotics for use in both government and commercial contexts. Employing liquid crystal tunable filter technology, the HSI system has an intuitive user interface that produces automated detections and real-time display of threats with an end user created library of threat signatures that is easily updated allowing for new hazardous materials. Unlike existing detection technologies that often require close proximity for sensing and so endanger operators and costly equipment, the handheld sensor allows the individual operator to detect threats from a safe distance. Uses of the sensor include locating production facilities of illegal drugs or IEDs by identification of materials on surfaces such as walls, floors, doors, deposits on production tools and residue on individuals. In addition, the sensor can be used for longer-range standoff applications such as hasty checkpoint or vehicle inspection of residue materials on surfaces or bulk material identification. The CISS Aperio™ sensor has faster data collection, faster image processing, and increased detection capability compared to previous sensors.

Processing, Fabrication and Characterization of Advanced Target Sensors Using Mercury Cadmium Telluride (MCT)

DTIC Science & Technology

2010-09-01

doped with Au, Hg, Cd, Be, or Ga); or (3) photoemissive such as metal silicides and negative electron affinity materials. Photoconductive and...plasma (ICP) etching and metallization as required by the design of the sensors at different levels of processing were carried out using either AZ...Second, after all the processing and metallization is completed, the sensor material (Hg1–xCdxTe) and the substrate (silicon) must be dry etched

Computational Electromagnetic Modeling of SansEC(Trade Mark) Sensors

NASA Technical Reports Server (NTRS)

Smith, Laura J.; Dudley, Kenneth L.; Szatkowski, George N.

2011-01-01

This paper describes the preliminary effort to apply computational design tools to aid in the development of an electromagnetic SansEC resonant sensor composite materials damage detection system. The computational methods and models employed on this research problem will evolve in complexity over time and will lead to the development of new computational methods and experimental sensor systems that demonstrate the capability to detect, diagnose, and monitor the damage of composite materials and structures on aerospace vehicles.

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.

High-Performance Flexible Force and Temperature Sensing Array with a Robust Structure

NASA Astrophysics Data System (ADS)

Kim, Min-Seok; Song, Han-Wook; Park, Yon-Kyu

We have developed a flexible tactile sensor array capable of sensing physical quantities, e.g. force and temperature with high-performances and high spatial resolution. The fabricated tactile sensor consists of 8 × 8 force measuring array with 1 mm spacing and a thin metal (copper) temperature sensor. The flexible force sensing array consists of sub-millimetre-size bar-shaped semi-conductor strain gage array attached to a thin and flexible printed circuit board covered by stretchable elastomeric material on both sides. This design incorporates benefits of both materials; the semi-conductor's high performance and the polymer's mechanical flexibility and robustness, while overcoming their drawbacks of those two materials. Special fabrication processes, so called “dry-transfer technique” have been used to fabricate the tactile sensor along with standard micro-fabrication processes.

Passive-quadrature demodulated localized-Michelson fiber-optic strain sensor embedded in composite materials

NASA Astrophysics Data System (ADS)

Valis, Tomas; Tapanes, Edward; Liu, Kexing; Measures, Raymond M.

1991-04-01

A strain sensor embedded in composite materials that is intrinsic, all fiber, local, and phase demodulated is described. It is the combination of these necessary elements that represents an advance in the state of the art. Sensor localization is achieved by using a pair of mirror-ended optical fibers of different lengths that are mechanically coupled up until the desired gauge length for common-mode suppression has been reached. This fiber-optic sensor has been embedded in both thermoset (Kevlar/epoxy and graphite/epoxy) and thermoplastic (graphite/PEEK) composite materials in order to make local strain measurements at the lamina level. The all-fiber system uses a 3 x 3 coupler for phase demodulation. Parameters such as strain sensitivity, transverse strain sensitivity, failure strain, and frequency response are discussed, along with applications.

A study of the applicability of gallium arsenide and silicon carbide as aerospace sensor materials

NASA Technical Reports Server (NTRS)

Hurley, John S.

1990-01-01

Most of the piezoresistive sensors, to date, are made of silicon and germanium. Unfortunately, such materials are severly restricted in high temperature environments. By comparing the effects of temperature on the impurity concentrations and piezoresistive coefficients of silicon, gallium arsenide, and silicon carbide, it is being determined if gallium arsenide and silicon carbide are better suited materials for piezoresistive sensors in high temperature environments. The results show that the melting point for gallium arsenide prevents it from solely being used in high temperature situations, however, when used in the alloy Al(x)Ga(1-x)As, not only the advantage of the wider energy band gas is obtained, but also the higher desire melting temperature. Silicon carbide, with its wide energy band gap and higher melting temperature suggests promise as a high temperature piezoresistive sensor.

Biosensing with Förster Resonance Energy Transfer Coupling between Fluorophores and Nanocarbon Allotropes

PubMed Central

Ding, Shaowei; Cargill, Allison A.; Das, Suprem R.; Medintz, Igor L.; Claussen, Jonathan C.

2015-01-01

Nanocarbon allotropes (NCAs), including zero-dimensional carbon dots (CDs), one-dimensional carbon nanotubes (CNTs) and two-dimensional graphene, exhibit exceptional material properties, such as unique electrical/thermal conductivity, biocompatibility and high quenching efficiency, that make them well suited for both electrical/electrochemical and optical sensors/biosensors alike. In particular, these material properties have been exploited to significantly enhance the transduction of biorecognition events in fluorescence-based biosensing involving Förster resonant energy transfer (FRET). This review analyzes current advances in sensors and biosensors that utilize graphene, CNTs or CDs as the platform in optical sensors and biosensors. Widely utilized synthesis/fabrication techniques, intrinsic material properties and current research examples of such nanocarbon, FRET-based sensors/biosensors are illustrated. The future outlook and challenges for the research field are also detailed. PMID:26110411

Cancer Survival Estimates Due to Non-Uniform Loss to Follow-Up and Non-Proportional Hazards

PubMed

K M, Jagathnath Krishna; Mathew, Aleyamma; Sara George, Preethi

2017-06-25

Background: Cancer survival depends on loss to follow-up (LFU) and non-proportional hazards (non-PH). If LFU is high, survival will be over-estimated. If hazard is non-PH, rank tests will provide biased inference and Cox-model will provide biased hazard-ratio. We assessed the bias due to LFU and non-PH factor in cancer survival and provided alternate methods for unbiased inference and hazard-ratio. Materials and Methods: Kaplan-Meier survival were plotted using a realistic breast cancer (BC) data-set, with >40%, 5-year LFU and compared it using another BC data-set with <15%, 5-year LFU to assess the bias in survival due to high LFU. Age at diagnosis of the latter data set was used to illustrate the bias due to a non-PH factor. Log-rank test was employed to assess the bias in p-value and Cox-model was used to assess the bias in hazard-ratio for the non-PH factor. Schoenfeld statistic was used to test the non-PH of age. For the non-PH factor, we employed Renyi statistic for inference and time dependent Cox-model for hazard-ratio. Results: Five-year BC survival was 69% (SE: 1.1%) vs. 90% (SE: 0.7%) for data with low vs. high LFU respectively. Age (<45, 46-54 & >54 years) was a non-PH factor (p-value: 0.036). However, survival by age was significant (log-rank p-value: 0.026), but not significant using Renyi statistic (p=0.067). Hazard ratio (HR) for age using Cox-model was 1.012 (95%CI: 1.004 -1.019) and the same using time-dependent Cox-model was in the other direction (HR: 0.997; 95% CI: 0.997- 0.998). Conclusion: Over-estimated survival was observed for cancer with high LFU. Log-rank statistic and Cox-model provided biased results for non-PH factor. For data with non-PH factors, Renyi statistic and time dependent Cox-model can be used as alternate methods to obtain unbiased inference and estimates. Creative Commons Attribution License

Involvement of COX-2 in nickel elution from a wire implanted subcutaneously in mice.

PubMed

Sato, Taiki; Kishimoto, Yu; Asakawa, Sanki; Mizuno, Natsumi; Hiratsuka, Masahiro; Hirasawa, Noriyasu

2016-07-01

Many types of medical alloys include nickel (Ni), and the elution of Ni ions from these materials causes toxicities and inflammation. We have previously reported that inflammation enhances Ni elution, although the molecular mechanisms underlying this effect remain unclear. In this study, we investigated how inflammatory responses enhanced Ni elution in a wire-implantation mouse model. Subcutaneous implantation of Ni wire induced the expression of cyclooxygenase-2 (COX-2) and microsomal prostaglandin E synthase-1 (mPGES-1) mRNA in the surrounding tissues. Immunostaining analysis showed that cells expressing COX-2 were mainly fibroblast-like cells 8h after implantation of a Ni wire, but were mainly infiltrated leukocytes at 24h. NiCl2 induced the expression of COX-2 mRNA in primary fibroblasts, neutrophils, RAW 264 cells, and THP-1 cells, indicating that Ni ions can induce COX-2 expression in various types of cells. The elution of Ni ions from the implanted Ni wire at 8h was reduced by dexamethasone (Dex), indomethacin (Ind), or celecoxib (Cel) treatment. Ni wire implantation induced an increase in mRNA levels for anaerobic glycolytic pathway components glucose transporter 1 (GLUT1), hexokinase 2 (HK2), lactate dehydrogenase A (LDHA), and monocarboxylate transporter 4 (MCT4); the expression of these genes was also inhibited by Dex, Ind, and Cel. In primary fibroblasts, the expression of these mRNAs and the production of lactate were induced by NiCl2 and further potentiated by PGE2. Furthermore, Ni wire-induced infiltration of inflammatory leukocytes was significantly reduced by Dex, Ind, or Cel. Depletion of neutrophils with a specific antibody caused reduction of both leukocyte infiltration and Ni elution. These results indicate that Ni ions eluted from wire induced COX-2 expression, which further promoted elution of Ni ions by increasing lactate production and leukocyte infiltration. Since COX inhibitors and Dex reduced the elution of Ni ions, these drugs may be useful for prevention of metal-related inflammation and allergy. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Analysis and experimental study on the strain transfer mechanism of an embedded basalt fiber-encapsulated fiber Bragg grating sensor

NASA Astrophysics Data System (ADS)

Zhang, Zhenglin; Wang, Yuan; Sun, Yangyang; Zhang, Qinghua; You, Zewei; Huang, Xiaodi

2017-01-01

The precision of the encapsulated fiber optic sensor embedded into a host suffers from the influences of encapsulating materials. Furthermore, an interface transfer effect of strain sensing exists. This study uses an embedded basalt fiber-encapsulated fiber Bragg grating (FBG) sensor as the research object to derive an expression in a multilayer interface strain transfer coefficient by considering the mechanical properties of the host material. The direct impact of the host material on the strain transfer at an embedded multipoint continuous FBG (i.e., multiple gratings written on a single optical fiber) monitoring strain sensor, which was self-developed and encapsulated with basalt fiber, is studied to present the strain transfer coefficients corresponding to the positions of various gratings. The strain transfer coefficients of the sensor are analyzed based on the experiments designed for this study. The error of the experimental results is ˜2 μɛ when the strain is at 60 μɛ and below. Moreover, the measured curves almost completely coincide with the theoretical curves. The changes in the internal strain field inside the embedded structure of the basalt fiber-encapsulated FBG strain sensor could be easily monitored. Hence, important references are provided to measure the internal stress strain of the sensor.

Auxetic Mechanical Metamaterials to Enhance Sensitivity of Stretchable Strain Sensors.

PubMed

Jiang, Ying; Liu, Zhiyuan; Matsuhisa, Naoji; Qi, Dianpeng; Leow, Wan Ru; Yang, Hui; Yu, Jiancan; Chen, Geng; Liu, Yaqing; Wan, Changjin; Liu, Zhuangjian; Chen, Xiaodong

2018-03-01

Stretchable strain sensors play a pivotal role in wearable devices, soft robotics, and Internet-of-Things, yet these viable applications, which require subtle strain detection under various strain, are often limited by low sensitivity. This inadequate sensitivity stems from the Poisson effect in conventional strain sensors, where stretched elastomer substrates expand in the longitudinal direction but compress transversely. In stretchable strain sensors, expansion separates the active materials and contributes to the sensitivity, while Poisson compression squeezes active materials together, and thus intrinsically limits the sensitivity. Alternatively, auxetic mechanical metamaterials undergo 2D expansion in both directions, due to their negative structural Poisson's ratio. Herein, it is demonstrated that such auxetic metamaterials can be incorporated into stretchable strain sensors to significantly enhance the sensitivity. Compared to conventional sensors, the sensitivity is greatly elevated with a 24-fold improvement. This sensitivity enhancement is due to the synergistic effect of reduced structural Poisson's ratio and strain concentration. Furthermore, microcracks are elongated as an underlying mechanism, verified by both experiments and numerical simulations. This strategy of employing auxetic metamaterials can be further applied to other stretchable strain sensors with different constituent materials. Moreover, it paves the way for utilizing mechanical metamaterials into a broader library of stretchable electronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electro-optic voltage sensor head

DOEpatents

Crawford, T.M.; Davidson, J.R.; Woods, G.K.

1999-08-17

The invention is an electro-optic voltage sensor head designed for integration with existing types of high voltage transmission and distribution apparatus. The sensor head contains a transducer, which comprises a transducing material in which the Pockels electro-optic effect is observed. In the practice of the invention at least one beam of electromagnetic radiation is routed into the transducing material of the transducer in the sensor head. The beam undergoes an electro-optic effect in the sensor head when the transducing material is subjected to an E-field. The electro-optic effect is observed as a differential phase a shift, also called differential phase modulation, of the beam components in orthogonal planes of the electromagnetic radiation. In the preferred embodiment the beam is routed through the transducer along an initial axis and then reflected by a retro-reflector back substantially parallel to the initial axis, making a double pass through the transducer for increased measurement sensitivity. The preferred embodiment of the sensor head also includes a polarization state rotator and at least one beam splitter for orienting the beam along major and minor axes and for splitting the beam components into two signals which are independent converse amplitude-modulated signals carrying E-field magnitude and hence voltage information from the sensor head by way of optic fibers. 6 figs.

Electro-optic voltage sensor head

DOEpatents

Crawford, Thomas M.; Davidson, James R.; Woods, Gregory K.

1999-01-01

The invention is an electro-optic voltage sensor head designed for integration with existing types of high voltage transmission and distribution apparatus. The sensor head contains a transducer, which comprises a transducing material in which the Pockels electro-optic effect is observed. In the practice of the invention at least one beam of electromagnetic radiation is routed into the transducing material of the transducer in the sensor head. The beam undergoes an electro-optic effect in the sensor head when the transducing material is subjected to an E-field. The electro-optic effect is observed as a differential phase a shift, also called differential phase modulation, of the beam components in orthogonal planes of the electromagnetic radiation. In the preferred embodiment the beam is routed through the transducer along an initial axis and then reflected by a retro-reflector back substantially parallel to the initial axis, making a double pass through the transducer for increased measurement sensitivity. The preferred embodiment of the sensor head also includes a polarization state rotator and at least one beam splitter for orienting the beam along major and minor axes and for splitting the beam components into two signals which are independent converse amplitude-modulated signals carrying E-field magnitude and hence voltage information from the sensor head by way of optic fibers.

Hollow-Structured Graphene-Silicone-Composite-Based Piezoresistive Sensors: Decoupled Property Tuning and Bending Reliability.

PubMed

Luo, Ningqi; Huang, Yan; Liu, Jing; Chen, Shih-Chi; Wong, Ching Ping; Zhao, Ni

2017-10-01

A versatile flexible piezoresistive sensor should maintain high sensitivity in a wide linear range, and provide a stable and repeatable pressure reading under bending. These properties are often difficult to achieve simultaneously with conventional filler-matrix composite active materials, as tuning of one material component often results in change of multiple sensor properties. Here, a material strategy is developed to realize a 3D graphene-poly(dimethylsiloxane) hollow structure, where the electrical conductivity and mechanical elasticity of the composite can be tuned separately by varying the graphene layer number and the poly(dimethylsiloxane) composition ratio, respectively. As a result, the sensor sensitivity and linear range can be easily improved through a decoupled tuning process, reaching a sensitivity of 15.9 kPa -1 in a 60 kPa linear region, and the sensor also exhibits fast response (1.2 ms rising time) and high stability. Furthermore, by optimizing the density of the graphene percolation network and thickness of the composite, the stability and repeatability of the sensor output under bending are improved, achieving a measurement error below 6% under bending radius variations from -25 to +25 mm. Finally, the potential applications of these sensors in wearable medical devices and robotic vision are explored. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wireless Temperature Sensor Having No Electrical Connections and Sensing Method for Use Therewith

NASA Technical Reports Server (NTRS)

Woodard, Marie (Inventor)

2014-01-01

A wireless temperature sensor includes an electrical conductor and a dielectric material on the conductor. The conductor is electrically unconnected and is shaped for storage of an electric field and a magnetic field. In the presence of a time-varying magnetic field, the conductor resonates to generate harmonic electric and magnetic field responses, each of which has a frequency associated therewith. The material is selected such that it experiences changes in either dielectric or magnetic permeability attributes in the presence of a temperature change. Shifts from the sensor's baseline frequency response indicate that the material has experienced a temperature change.

Detection of magnetic resonance signals using a magnetoresistive sensor

DOEpatents

Budker, Dmitry; Pines, Alexander; Xu, Shoujun; Hilty, Christian; Ledbetter, Micah P; Bouchard, Louis S

2013-10-01

A method and apparatus are described wherein a micro sample of a fluidic material may be assayed without sample contamination using NMR techniques, in combination with magnetoresistive sensors. The fluidic material to be assayed is first subject to pre-polarization, in one embodiment, by passage through a magnetic field. The magnetization of the fluidic material is then subject to an encoding process, in one embodiment an rf-induced inversion by passage through an adiabatic fast-passage module. Thereafter, the changes in magnetization are detected by a pair of solid-state magnetoresistive sensors arranged in gradiometer mode. Miniaturization is afforded by the close spacing of the various modules.

In-process deformation measurements of translucent high speed fibre-reinforced disc rotors

NASA Astrophysics Data System (ADS)

Philipp, Katrin; Filippatos, Angelos; Koukourakis, Nektarios; Kuschmierz, Robert; Leithold, Christoph; Langkamp, Albert; Fischer, Andreas; Czarske, Jürgen

2015-07-01

The high stiffness to weight ratio of glass fibre-reinforced polymers (GFRP) makes them an attractive material for rotors e.g. in the aerospace industry. We report on recent developments towards non-contact, in-situ deformation measurements with temporal resolution up to 200 µs and micron measurement uncertainty. We determine the starting point of damage evolution inside the rotor material through radial expansion measurements. This leads to a better understanding of dynamic material behaviour regarding damage evolution and the prediction of damage initiation and propagation. The measurements are conducted using a novel multi-sensor system consisting of four laser Doppler distance (LDD) sensors. The LDD sensor, a two-wavelength Mach-Zehnder interferometer was already successfully applied for dynamic deformation measurements at metallic rotors. While translucency of the GFRP rotor material limits the applicability of most optical measurement techniques due to speckles from both surface and volume of the rotor, the LDD profits from speckles and is not disturbed by backscattered laser light from the rotor volume. The LDD sensor evaluates only signals from the rotor surface. The anisotropic glass fibre-reinforcement results in a rotationally asymmetric dynamic deformation. A novel signal processing algorithm is applied for the combination of the single sensor signals to obtain the shape of the investigated rotors. In conclusion, the applied multi-sensor system allows high temporal resolution dynamic deformation measurements. First investigations regarding damage evolution inside GFRP are presented as an important step towards a fundamental understanding of the material behaviour and the prediction of damage initiation and propagation.

Overview of Fiber Optic Sensor Technologies for Strain/Temperature Sensing Applications in Composite Materials

PubMed Central

Ramakrishnan, Manjusha; Rajan, Ginu; Semenova, Yuliya; Farrell, Gerald

2016-01-01

This paper provides an overview of the different types of fiber optic sensors (FOS) that can be used with composite materials and also their compatibility with and suitability for embedding inside a composite material. An overview of the different types of FOS used for strain/temperature sensing in composite materials is presented. Recent trends, and future challenges for FOS technology for condition monitoring in smart composite materials are also discussed. This comprehensive review provides essential information for the smart materials industry in selecting of appropriate types of FOS in accordance with end-user requirements. PMID:26784192

Giant magnetoresistive sensor

DOEpatents

Stearns, Daniel G.; Vernon, Stephen P.; Ceglio, Natale M.; Hawryluk, Andrew M.

1999-01-01

A magnetoresistive sensor element with a three-dimensional micro-architecture is capable of significantly improved sensitivity and highly localized measurement of magnetic fields. The sensor is formed of a multilayer film of alternately magnetic and nonmagnetic materials. The sensor is optimally operated in a current perpendicular to plane mode. The sensor is useful in magnetic read/write heads, for high density magnetic information storage and retrieval.

Elastomeric Sensing of Pressure with Liquid Metal and Wireless Inductive Coupling

NASA Technical Reports Server (NTRS)

Dick, Jacob; Zou, Xiyue; Hogan, Ben; Tumalle, Jonathan; Etikyala, Sowmith; Fung, Diego; Charles, Watley; Gu, Tianye; Hull, Patrick V.; Mazzeo, Aaron D.

2017-01-01

This project describes resistance-based soft sensors filled with liquid metal, which permit measurements of large strains (0 percent to 110 percent), associated with small forces of less than 30 Newtons. This work also demonstrates a methodology for wireless transfer of these strain measurements without connected electrodes. These sensors allow intermittent detection of pressure on soft membranes with low force. Adapting these sensors for passive wireless pressure sensing will eliminate the need for embedded batteries, and will allow the sensors to transmit pressure data through non-conductive materials including glass and acrylic. The absence of batteries allows us to embed these sensors into materials for long-term use because the sensors only use passive analog circuit elements. We found the oxidation of the liquid metal (eutectic gallium indium) plays a role in the repeatability of the soft sensors. We investigated how the oxidation layer affected the behavior of the sensor by encapsulating materials (silicone, fluorosilicone, and PVC) with varied permeabilities to oxygen. We measured the effects of mechanical loading on the oxidation layer and the effects of wireless inductive coupling on the oxidation layer. We concluded our research by investigating the effects of embedding self-resonant circuits into polydimethylsiloxane (PDMS). Efforts to design engineered systems with soft materials are a growing field with progress in soft robotics, epidermal electronics, and wearable electronics. In the field of soft robotics, PDMS-based grippers are capable of picking up delicate objects because their form-fitting properties allow them to conform to the shape of objects more easily than conventional robotic grippers. Epidermal devices also use PDMS as a substrate to hold electronic components such as radios, sensors, and power supply circuits. Additionally, PDMS-based soft sensors can monitor human motion with liquid metal embedded within micro-channels. Passive wireless sensors have applications in structural health monitoring and medical health monitoring. Doctors can take wireless blood pressure measurements inside arteries to monitor the progression of heart disease. Glaucoma patients can use this technology to monitor the pressure in their eyes to track the progression of the disease.

Development of a Batch Fabrication Process for Chemical Nanosensors: Recent Advancements at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Biaggi-Labiosa, Azlin M.

2014-01-01

A major objective in aerospace sensor development is to produce sensors that are small in size, easy to batch fabricate and low in cost, and have low power consumption. Chemical sensors involving nanostructured materials can provide these characteristics as well as the potential for the development of sensor systems with unique properties and improved performance. However, the fabrication and processing of nanostructures for sensor applications currently is limited by the ability to control their location on the sensor platform, which in turn hinders the progress for batch fabrication. This presentation will discuss the following: the development of a novel room temperature methane (CH4) sensor fabricated using porous tin oxide (SnO2) nanorods as the sensing material, the advantages of using nanomaterials in sensor designs, the challenges encountered with the integration of nanostructures into microsensordevices, and the different methods that have been attempted to address these challenges. An approach for the mass production of sensors with nanostructures using a method developed by our group at the NASA Glenn Research Center to control the alignment of nanostructures onto a sensor platform will also be described.

Nanoalloy Printed and Pulse-Laser Sintered Flexible Sensor Devices with Enhanced Stability and Materials Compatibility

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

Zhao, Wei; Rovore, Thomas; Weerawarne, Darshana

2015-06-02

While conformal and wearable devices have become one of the most desired formats for printable electronics, it is challenging to establish a scalable process that produces stable conductive patterns but also uses substrates compatible with widely available wearable materials. Here, we describe findings of an investigation of a nanoalloy ink printed and pulsed laser sintered conductive patterns as flexible functional devices with enhanced stability and materials compatibility. While nanoparticle inks are desired for printable electronics, almost all existing nanoparticle inks are based on single-metal component, which, as an electronic element, is limited by its inherent stabilities of the metal suchmore » as propensity of metal oxidation and mobility of metal ions, especially in sintering processes. The work here has demonstrated the first example in exploiting plasmonic coupling of nanoalloys and pulsed-laser energy with controllable thermal penetration. The experimental and theoretical results have revealed clear correlation between the pulsed laser parameters and the nanoalloy structural characteristics. The superior performance of the resulting flexible sensor device, upon imparting nanostructured sensing materials, for detecting volatile organic compounds has significant implications to developing stable and wearable sensors for monitoring environmental pollutants and breath biomarkers. This simple “nanoalloy printing 'laser sintering' nanostructure printing” process is entirely general to many different sensor devices and nanostructured sensing materials, enabling the ability to easily construct sophisticated sensor array.« less

Nanoalloy Printed and Pulse-Laser Sintered Flexible Sensor Devices with Enhanced Stability and Materials Compatibility.

PubMed

Zhao, Wei; Rovere, Thomas; Weerawarne, Darshana; Osterhoudt, Gavin; Kang, Ning; Joseph, Pharrah; Luo, Jin; Shim, Bonggu; Poliks, Mark; Zhong, Chuan-Jian

2015-06-23

While conformal and wearable devices have become one of the most desired formats for printable electronics, it is challenging to establish a scalable process that produces stable conductive patterns but also uses substrates compatible with widely available wearable materials. Here, we describe findings of an investigation of a nanoalloy ink printed and pulsed-laser sintered conductive patterns as flexible functional devices with enhanced stability and materials compatibility. While nanoparticle inks are desired for printable electronics, almost all existing nanoparticle inks are based on single-metal component, which, as an electronic element, is limited by its inherent stabilities of the metal such as propensity of metal oxidation and mobility of metal ions, especially in sintering processes. The work here has demonstrated the first example in exploiting plasmonic coupling of nanoalloys and pulsed-laser energy with controllable thermal penetration. The experimental and theoretical results have revealed clear correlation between the pulsed laser parameters and the nanoalloy structural characteristics. The superior performance of the resulting flexible sensor device, upon imparting nanostructured sensing materials, for detecting volatile organic compounds has significant implications to developing stable and wearable sensors for monitoring environmental pollutants and breath biomarkers. This simple "nanoalloy printing-laser sintering-nanostructure printing" process is entirely general to many different sensor devices and nanostructured sensing materials, enabling the ability to easily construct sophisticated sensor array.

Method and apparatus for optical temperature measurement

DOEpatents

O'Rourke, P.E.; Livingston, R.R.; Prather, W.S.

1994-09-20

A temperature probe and a method for using said probe for temperature measurements based on changes in light absorption by the probe are disclosed. The probe comprises a first and a second optical fiber that carry light to and from the probe, and a temperature sensor material, the absorbance of which changes with temperature, through which the light is directed. Light is directed through the first optical fiber, passes through the temperature sensor material, and is transmitted by a second optical fiber from the material to a detector. Temperature-dependent and temperature-independent factors are derived from measurements of the transmitted light intensity. For each sensor material, the temperature T is a function of the ratio, R, of these factors. The temperature function f(R) is found by applying standard data analysis techniques to plots of T versus R at a series of known temperatures. For a sensor having a known temperature function f(R) and known characteristic and temperature-dependent factors, the temperature can be computed from a measurement of R. Suitable sensor materials include neodymium-doped borosilicate glass, accurate to [+-]0.5 C over an operating temperature range of about [minus]196 C to 400 C; and a mixture of D[sub 2]O and H[sub 2]O, accurate to [+-]0.1 C over an operating range of about 5 C to 90 C. 13 figs.

Method and apparatus for optical temperature measurement

DOEpatents

O'Rourke, Patrick E.; Livingston, Ronald R.; Prather, William S.

1994-01-01

A temperature probe and a method for using said probe for temperature measurements based on changes in light absorption by the probe. The probe comprises a first and a second optical fiber that carry light to and from the probe, and a temperature sensor material, the absorbance of which changes with temperature, through which the light is directed. Light is directed through the first optical fiber, passes through the temperature sensor material, and is transmitted by a second optical fiber from the material to a detector. Temperature-dependent and temperature-independent factors are derived from measurements of the transmitted light intensity. For each sensor material, the temperature T is a function of the ratio, R, of these factors. The temperature function f(R) is found by applying standard data analysis techniques to plots of T versus R at a series of known temperatures. For a sensor having a known temperature function f(R) and known characteristic and temperature-dependent factors, the temperature can be computed from a measurement of R. Suitable sensor materials include neodymium-doped boresilicate glass, accurate to .+-.0.5.degree. C. over an operating temperature range of about -196.degree. C. to 400.degree. C.; and a mixture of D.sub.2 O and H.sub.2 O, accurate to .+-.0.1.degree. C. over an operating range of about 5.degree. C. to 90.degree. C.

Active Control Technology at NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Antcliff, Richard R.; McGowan, Anna-Marie R.

2000-01-01

NASA Langley has a long history of attacking important technical opportunities from a broad base of supporting disciplines. The research and development at Langley in this subject area range from the test tube to the test flight. The information covered here will range from the development of innovative new materials, sensors and actuators, to the incorporation of smart sensors and actuators in practical devices, to the optimization of the location of these devices, to, finally, a wide variety of applications of these devices utilizing Langley's facilities and expertise. Advanced materials are being developed for sensors and actuators, as well as polymers for integrating smart devices into composite structures. Contributions reside in three key areas: computational materials; advanced piezoelectric materials; and integrated composite structures. The computational materials effort is focused on developing predictive tools for the efficient design of new materials with the appropriate combination of properties for next generation smart airframe systems. Research in the area of advanced piezoelectrics includes optimizing the efficiency, force output, use temperature, and energy transfer between the structure and device for both ceramic and polymeric materials. For structural health monitoring, advanced non-destructive techniques including fiber optics are being developed for detection of delaminations, cracks and environmental deterioration in aircraft structures. The computational materials effort is focused on developing predictive tools for the efficient design of new materials with the appropriate combination of properties for next generation smart airframe system. Innovative fabrication techniques processing structural composites with sensor and actuator integration are being developed.

Tailoring the mechanical properties of SU-8/clay nanocomposites: polymer microcantilever fabrication perspective

NASA Astrophysics Data System (ADS)

Chen, Hao; Ojijo, Vincent; Cele, Hastings; Joubert, Trudi; Suprakas, Sinha Ray; Land, Kevin

2014-06-01

SU-8/Clay nanocomposite is considered as a candidate material for microcantilever sensor fabrication. Organically modified montmorillonite clay nanoparticles are dispersed in the universally used negative photoresist polymer SU-8, for a low cost material, which is also biocompatible. If varying the clay loading of the composite material yields a variation of the Young's modulus, the tailored material stiffness presents an opportunity for fabrication of microcantilevers with tunable sensor sensitivity. With this microcantilever application perspective, mechanical and thermal properties of the material were investigated. SU-8/Clay nanocomposite samples were prepared with clay loadings from 1wt% - 10wt%. Tensile test results show a general trend of increase in composite modulus with an increase in the clay loading up to 7wt%, followed by a small drop at 10wt%. The composite material indeed yields moderate variation of the Young's modulus. It was also found that the thermal degradation peak of the material occurred at 300°C, which is beyond the operating temperature of typical microcantilever sensor applications. The fabrication of a custom designed microcantilever array chip with the SU-8/Clay nanocomposite material was achieved in a class 100 cleanroom, using spin-coating and photolithography microfabrication techniques. The optimization of the process for fabricating microcantilever with the SU-8/Clay nanocomposite material is discussed in this paper. The results of this research are promising for cheaper mass production of low cost disposable, yet sensitive, microcantilever sensor elements, including biosensor applications.

Assembly and testing of microparticle and microcapsule smart tattoo materials

NASA Astrophysics Data System (ADS)

McShane, Michael J.

2007-01-01

Microscale biochemical sensors are attractive for in vitro diagnostics and disease management, as well as medical and biological research applications. Fluorescent sensors, coupling specific glucose-binding proteins with fluorescent readout methods, have been developed for this purpose. Our work has focused on the development of assembly and packaging systems for producing micro- and nanoscale sensing components that can be used as implants, intracellular reporters, or as elements in larger systems. Both hybrid organic/inorganic particles and hollow microshells have been developed to physically couple the sensing materials together in biocompatible, semipermeable packages. Fabrication details and sensor characterization are used to demonstrate the potential of these sensor concepts.

Optical fibre luminescence sensor for real-time LDR brachytherapy dosimetry

NASA Astrophysics Data System (ADS)

Woulfe, P.; Sullivan, F. J.; O'Keeffe, S.

2016-05-01

An optical fibre sensor for monitoring low dose radiation is presented. The sensor is based on a scintillation material embedded within the optical fibre core, which emits visible light when exposed to low level ionising radiation. The incident level of ionising radiation can be determined by analysing the optical emission. An optical fibre sensor is presented, based on radioluminescence whereby radiation sensitive scintillation material, terbium doped gadolinium oxysulphide (Gd2O2S:Tb), is embedded in a cavity of 250μm of a 500μm plastic optical fibre. The sensor is designed for in-vivo monitoring of the radiation dose during radio-active seed implantation for brachytherapy, in prostate cancer treatment, providing oncologists with real-time information of the radiation dose to the target area and/or nearby critical structures. The radiation from the brachytherapy seeds causes emission of visible light from the scintillation material through the process of radioluminescence, which penetrates the fibre, propagating along the optical fibre for remote detection using a multi-pixel photon counter. The sensor demonstrates a high sensitivity to Iodine-125, the radioactive source most commonly used in brachytherapy for treating prostate cancer.

Effect of degree of crosslinking and polymerization of 3D printable polymer/ionic liquid composites on performance of stretchable piezoresistive sensors

NASA Astrophysics Data System (ADS)

Lee, Jeongwoo; Faruk Emon, Md Omar; Vatani, Morteza; Choi, Jae-Won

2017-03-01

Ionic liquid (IL)/polymer composites (1-ethyl-3-methyl-imidazolium tetrafluoroborate (EMIMBF4)/2-[[(butylamino)carbonyl]oxy]ethyl acrylate (BACOEA)) were fabricated to use as sensing materials for stretchable piezoresistive tactile sensors. The detectability of the IL/polymer composites was enhanced because the ionic transport properties of EMIMBF4 in the composites were improved by the synergic actions between the coordinate sites generated by the local motion of BACOEA chain segments under enough activation energy. The performance of the piezoresistive sensors was investigated with the degree of crosslinking and polymerization of the IL/polymer composites. As the compressive strain was increased, the distance between two electrodes decreased, and the motion of polymer chains and IL occurred, resulting in a decrease in the electrical resistance of the sensors. We have confirmed that the sensitivity of the sensors are affected by the degree of crosslink and polymerization of the IL/polymer composites. In addition, all of the materials (skins, sensing material, and electrode) used in this study are photo-curable, and thus the stretchable piezoresistive tactile sensors can be successfully fabricated by 3D printing.

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.

Diffractive optical element in materials testing

NASA Astrophysics Data System (ADS)

Silvennoinen, Raimo V. J.; Peiponen, Kai-Erik

1998-09-01

The object of this paper is to present a sensor based on diffractive optics that can be applied for the materials testing. The present sensor, which is based on the use of a computer-generated hologram (CGH) exploits the holographic imagery. The CGH-sensor was introduced for inspection of surface roughness and flatness of metal surfaces. The results drawn out by the present sensor are observed to be in accordance with the experimental data. Together with the double exposure holographic interferometry (DEHI) and digital electronic speckle pattern interferometry (DSPI) in elasticity inspection, the sensor was applied for the investigations of surface quality of opaque fragile materials, which are pharmaceutical compacts. The optical surface quality was observed to be related to the porosity of the pharmaceutical tablets. The CGH-sensor was also applied for investigations of optical quality of thin films as PLZT ceramics and coating of pharmaceutical compacts. The surfaces of PLZT samples showed fluctuations in optical curvature, and wedgeness for all the cases studied. For pharmaceutical compacts, the optical signals were observed to depend to a great extent on the optical constants of the coatings and the substrates, and in addition to the surface porosity under the coating.

Optical fibre luminescence sensor for real-time LDR brachytherapy dosimetry

NASA Astrophysics Data System (ADS)

Woulfe, P.; O'Keeffe, S.; Sullivan, F. J.

2018-02-01

An optical fibre sensor for monitoring low dose radiation is presented. The sensor is based on a scintillation material embedded within the optical fibre core, which emits visible light when exposed to low level ionising radiation. The incident level of ionising radiation can be determined by analysing the optical emission. An optical fibre sensor is developed, based on radioluminescence whereby radiation sensitive scintillation material, terbium doped gadolinium oxysulphide (Gd2O2S:Tb), is embedded in a cavity of 700μm of a 1mm plastic optical fibre. The sensor is designed for in-vivo monitoring of the radiation dose during radio-active seed implantation for low dose rate (LDR) brachytherapy, in prostate cancer treatment, providing radiation oncologists with real-time information of the radiation dose to the target area and/or nearby organs at risk (OARs). The radiation from the brachytherapy seeds causes emission of visible light from the scintillation material through the process of radioluminescence, which penetrates the fibre, propagating along the optical fibre for remote detection using a multi-pixel photon counter. The sensor demonstrates a high sensitivity to 0.397mCi of Iodine125, the radioactive source most commonly used in brachytherapy for treating prostate cancer.

Improved Optical-Fiber Temperature Sensors

NASA Technical Reports Server (NTRS)

Rogowski, Robert S.; Egalon, Claudio O.

1993-01-01

In optical-fiber temperature sensors of proposed type, phosphorescence and/or fluorescence in temperature-dependent coating layers coupled to photodetectors. Phosphorescent and/or fluorescent behavior(s) of coating material(s) depend on temperature; coating material or mixture of materials selected so one can deduce temperature from known temperature dependence of phosphorescence and/or fluorescence spectrum, and/or characteristic decay of fluorescence. Basic optical configuration same as that of optical-fiber chemical detectors described in "Making Optical-Fiber Chemical Detectors More Sensitive" (LAR-14525).

Radiopacity of endodontic materials on film and a digital sensor.

PubMed

Rasimick, Brian J; Shah, Rinal P; Musikant, Barry Lee; Deutsch, Allan S

2007-09-01

The purpose of this study was to compare the radiographic appearance of 12 endodontic materials as visualized on either Kodak Ultra-speed D speed film (Eastman Kodak Company, Rochester, NY) or a Gendex eHD digital sensor (Gendex Dental Systems, Milan, Italy). Ten discs of each material were radiographed alongside an aluminum alloy 1100 (Alcoa, Pittsburgh, PA) stepwedge that was used for reference. For every radiograph, the average grayscale value of the material was converted into absorbance notation and compared with that of the reference stepwedge in order to determine the equivalent radiopacity in terms of millimeters of Al 1100 per millimeter of material. Two-way repeated-measures analysis of variance testing detected significant differences with respect to imaging system, material, and the interaction of the two factors (p < 0.001). The difference in a material's radiopacity as measured on the digital sensor compared with film was greater than 10% for 4 of the 12 materials and over 40% for InnoEndo (Heraus Kulzer, Armonk, NY). It was speculated that barium fillers cause this effect.

Advanced Nanoporous Materials for Micro-Gravimetric Sensing to Trace-Level Bio/Chemical Molecules

PubMed Central

Xu, Pengcheng; Li, Xinxin; Yu, Haitao; Xu, Tiegang

2014-01-01

Functionalized nanoporous materials have been developed recently as bio/chemical sensing materials. Due to the huge specific surface of the nano-materials for molecular adsorption, high hopes have been placed on gravimetric detection with micro/nano resonant cantilevers for ultra-sensitive sensing of low-concentration bio/chemical substances. In order to enhance selectivity of the gravimetric resonant sensors to the target molecules, it is crucial to modify specific groups onto the pore-surface of the nano-materials. By loading the nanoporous sensing material onto the desired region of the mass-type transducers like resonant cantilevers, the micro-gravimetric bio/chemical sensors can be formed. Recently, such micro-gravimetric bio/chemical sensors have been successfully applied for rapid or on-the-spot detection of various bio/chemical molecules at the trace-concentration level. The applicable nanoporous sensing materials include mesoporous silica, zeolite, nanoporous graphene oxide (GO) and so on. This review article focuses on the recent achievements in design, preparation, functionalization and characterization of advanced nanoporous sensing materials for micro-gravimetric bio/chemical sensing. PMID:25313499

Structural Health Monitoring of Composite Materials Using Distributed Fiber Bragg Sensors

NASA Technical Reports Server (NTRS)

Grant, Joseph; Kual, Raj; Taylor, Scott; Jackson, Kurt V.; Myers, George; Wang, Y.; Sharma, A.; Burdine, Robert (Technical Monitor)

2002-01-01

Health monitoring of polymer matrix composite materials using fiber optic Bragg grating (FBG) sensors is accomplished using a tunable IR (infrared) laser via transmission mode. Results are presented from experiments of composite structures with FBG's embedded at various orientations, and surface measurements of various cryogenic composite vessels.

Investigation of hydrogen sulfide gas using Pd/Pt material based fiber Bragg grating sensor

NASA Astrophysics Data System (ADS)

Bedi, Amna; Rao, Dusari Nageswara; Kumar, Santosh

2018-02-01

In this work, Pd/Pt material based fiber Bragg grating (FBG) sensors has been proposed for detection of hydrogen sulfide gas. Here, characteristics of FBG parameters were numerically calculated and simulated. The variation in reflectivity based on refractive index has been shown. The reflectivity of FBG can be varied when refractive index is changed. The proposed sensor works on very low concentration i.e., 0% to 1%, which has the capability to detect in the early stage.

Fabrications and Performance of Wireless LC Pressure Sensors through LTCC Technology.

PubMed

Lin, Lin; Ma, Mingsheng; Zhang, Faqiang; Liu, Feng; Liu, Zhifu; Li, Yongxiang

2018-01-25

This paper presents a kind of passive wireless pressure sensor comprised of a planar spiral inductor and a cavity parallel plate capacitor fabricated through low-temperature co-fired ceramic (LTCC) technology. The LTCC material with a low Young's modulus of ~65 GPa prepared by our laboratory was used to obtain high sensitivity. A three-step lamination process was applied to construct a high quality cavity structure without using any sacrificial materials. The effects of the thickness of the sensing membranes on the sensitivity and detection range of the pressure sensors were investigated. The sensor with a 148 μm sensing membrane showed the highest sensitivity of 3.76 kHz/kPa, and the sensor with a 432 μm sensing membrane presented a high detection limit of 2660 kPa. The tunable sensitivity and detection limit of the wireless pressure sensors can meet the requirements of different scenes.

Spiral passive electromagnetic sensor (SPES) for smart sensing and de-icing

NASA Astrophysics Data System (ADS)

Iervolino, Onorio; Meo, Michele

2015-04-01

The objective of this work was to develop a wireless Spiral Passive Electromagnetic Sensor (SPES) to monitor the complex permittivity of a surrounding medium. The sensor is a self-resonating planar pattern of electrically conductive material. Investigation were conducted to demonstrate the capability of the SPES to monitor humidity and temperature gradients, and acting as an ice protection tool. An oscillating signal is used to interrogate remotely the sensor with a single loop antenna or wiring it directly to a spectrum analyser and monitoring the backscattering signal. The excited sensor responds with its own resonant frequency, amplitude and bandwidth that can be correlated to physical quantities to be monitored. Our studies showed the capability of the sensor to monitor temperature and humidity changes in composite materials and uniformly produce induction heating when the conductive path is activated by an external electric power supply that can be used for deicing of aircraft structures.

A magnetostatic-coupling based remote query sensor for environmental monitoring

NASA Technical Reports Server (NTRS)

Grimes, C. A.; Stoyanov, P. G.; Liu, Y.; Tong, C.; Ong, K. G.; Loiselle, K.; Shaw, M.; Doherty, S. A.; Seitz, W. R.

1999-01-01

A new type of in situ, remotely monitored magnetism-based sensor is presented that is comprised of an array of magnetically soft, magnetostatically-coupled ferromagnetic thin-film elements or particles combined with a chemically responsive material that swells or shrinks in response to the analyte of interest. As the chemically responsive material changes size the distance between the ferromagnetic elements changes, altering the inter-element magnetostatic coupling. This in turn changes the coercive force of the sensor, the amplitude of the voltage spikes detected in nearby pick-up coils upon magnetization reversal and the number of higher-order harmonics generated by the flux reversal. Since the sensor is monitored through changes in magnetic flux, no physical connections such as wires or cables are needed to obtain sensor information, nor is line of sight alignment required as with laser telemetry; the sensors can be detected from within sealed, opaque or thin metallic enclosures.

Optical and Electronic NO(x) Sensors for Applications in Mechatronics.

PubMed

Di Franco, Cinzia; Elia, Angela; Spagnolo, Vincenzo; Scamarcio, Gaetano; Lugarà, Pietro Mario; Ieva, Eliana; Cioffi, Nicola; Torsi, Luisa; Bruno, Giovanni; Losurdo, Maria; Garcia, Michael A; Wolter, Scott D; Brown, April; Ricco, Mario

2009-01-01

Current production and emerging NO(x) sensors based on optical and nanomaterials technologies are reviewed. In view of their potential applications in mechatronics, we compared the performance of: i) Quantum cascade lasers (QCL) based photoacoustic (PA) systems; ii) gold nanoparticles as catalytically active materials in field-effect transistor (FET) sensors, and iii) functionalized III-V semiconductor based devices. QCL-based PA sensors for NO(x) show a detection limit in the sub part-per-million range and are characterized by high selectivity and compact set-up. Electrochemically synthesized gold-nanoparticle FET sensors are able to monitor NO(x) in a concentration range from 50 to 200 parts per million and are suitable for miniaturization. Porphyrin-functionalized III-V semiconductor materials can be used for the fabrication of a reliable NO(x) sensor platform characterized by high conductivity, corrosion resistance, and strong surface state coupling.

Electrochemical DNA hybridization sensors based on conducting polymers.

PubMed

Rahman, Md Mahbubur; Li, Xiao-Bo; Lopa, Nasrin Siraj; Ahn, Sang Jung; Lee, Jae-Joon

2015-02-05

Conducting polymers (CPs) are a group of polymeric materials that have attracted considerable attention because of their unique electronic, chemical, and biochemical properties. This is reflected in their use in a wide range of potential applications, including light-emitting diodes, anti-static coating, electrochromic materials, solar cells, chemical sensors, biosensors, and drug-release systems. Electrochemical DNA sensors based on CPs can be used in numerous areas related to human health. This review summarizes the recent progress made in the development and use of CP-based electrochemical DNA hybridization sensors. We discuss the distinct properties of CPs with respect to their use in the immobilization of probe DNA on electrode surfaces, and we describe the immobilization techniques used for developing DNA hybridization sensors together with the various transduction methods employed. In the concluding part of this review, we present some of the challenges faced in the use of CP-based DNA hybridization sensors, as well as a future perspective.

Measurement of sound pressure and temperature in tissue-mimicking material using an optical fiber Bragg grating sensor.

PubMed

Imade, Keisuke; Kageyama, Takashi; Koyama, Daisuke; Watanabe, Yoshiaki; Nakamura, Kentaro; Akiyama, Iwaki

2016-10-01

The experimental investigation of an optical fiber Bragg grating (FBG) sensor for biomedical application is described. The FBG sensor can be used to measure sound pressure and temperature rise simultaneously in biological tissues exposed to ultrasound. The theoretical maximum values that can be measured with the FBG sensor are 73.0 MPa and 30 °C. In this study, measurement of sound pressure up to 5 MPa was performed at an ultrasound frequency of 2 MHz. A maximum temperature change of 6 °C was measured in a tissue-mimicking material. Values yielded by the FBG sensor agreed with those measured using a thermocouple and a hydrophone. Since this sensor is used to monitor the sound pressure and temperature simultaneously, it can also be used for industrial applications, such as ultrasonic cleaning of semiconductors under controlled temperatures.

Development of chipscale chalcogenide glass based infrared chemical sensors

NASA Astrophysics Data System (ADS)

Hu, Juejun; Musgraves, J. David; Carlie, Nathan; Zdyrko, Bogdan; Luzinov, Igor; Agarwal, Anu; Richardson, Kathleen; Kimerling, Lionel

2011-01-01

In this paper, we review the design, processing, and characterization of novel planar infrared chemical sensors. Chalcogenide glasses are identified as the material of choice for sensing given their wide infrared transparency as well as almost unlimited capacity for composition alloying and property tailoring. Three generations of on-chip spectroscopic chemical sensor devices we have developed: waveguide evanescent sensors, micro-disk cavity-enhanced sensors and micro-cavity photothermal sensors are discussed.

A non-resonant mass sensor to eliminate the "missing mass" effect during mass measurement of biological materials

NASA Astrophysics Data System (ADS)

Shrikanth, V.; Bobji, M. S.

2014-10-01

Resonant sensors and crystal oscillators for mass detection need to be excited at very high natural frequencies (MHz). Use of such systems to measure mass of biological materials affects the accuracy of mass measurement due to their viscous and/or viscoelastic properties. The measurement limitation of such sensor system is the difficulty in accounting for the "missing mass" of the biological specimen in question. A sensor system has been developed in this work, to be operated in the stiffness controlled region at very low frequencies as compared to its fundamental natural frequency. The resulting reduction in the sensitivity due to non-resonant mode of operation of this sensor is compensated by the high resolution of the sensor. The mass of different aged drosophila melanogaster (fruit fly) is measured. The difference in its mass measurement during resonant mode of operation is also presented. That, viscosity effects do not affect the working of this non-resonant mass sensor is clearly established by direct comparison.

COX16 promotes COX2 metallation and assembly during respiratory complex IV biogenesis

PubMed Central

Aich, Abhishek; Wang, Cong; Chowdhury, Arpita; Ronsör, Christin; Pacheu-Grau, David; Richter-Dennerlein, Ricarda; Dennerlein, Sven

2018-01-01

Cytochrome c oxidase of the mitochondrial oxidative phosphorylation system reduces molecular oxygen with redox equivalent-derived electrons. The conserved mitochondrial-encoded COX1- and COX2-subunits are the heme- and copper-center containing core subunits that catalyze water formation. COX1 and COX2 initially follow independent biogenesis pathways creating assembly modules with subunit-specific, chaperone-like assembly factors that assist in redox centers formation. Here, we find that COX16, a protein required for cytochrome c oxidase assembly, interacts specifically with newly synthesized COX2 and its copper center-forming metallochaperones SCO1, SCO2, and COA6. The recruitment of SCO1 to the COX2-module is COX16- dependent and patient-mimicking mutations in SCO1 affect interaction with COX16. These findings implicate COX16 in CuA-site formation. Surprisingly, COX16 is also found in COX1-containing assembly intermediates and COX2 recruitment to COX1. We conclude that COX16 participates in merging the COX1 and COX2 assembly lines. PMID:29381136

Study of PEG Tether Length of Pegylated-Lipid Sensing Films in QCM Odor Sensors

NASA Astrophysics Data System (ADS)

Wyszynski, Bartosz; Somboon, Pakpum; Nakamoto, Takamichi

Odor sensing system using quartz crystal microbalance (QCM) sensor array and pattern recognition technique has been for a long time an important research topic. Research of novel sensing materials for QCM odor sensors is vital for realization of artificial olfaction and related devices such as odor recorder. Herein we study quartz crystal microbalance (QCM, 20 MHz, AT-cut) sensors coated with lipopolymers with polyethylene glycol (PEG) as a tether. The tether's molecular weights were 1000, 2000 and 5000. In addition, we fabricated QCM sensors coated with PEGs of molecular weights 1000, 2000 and 4000. The fabricated sensors' properties were evaluated during experiments of exposures to vapors of alcohols, esters and acids. From the obtained results it is clear that the tether's length (molecular weight) is an important factor influencing the resulting material's sensing properties. Sensititivity patterns of the lipopolymeric sensors were clealrly different from the ones for respective polymers. The obtained sensors seem to have a good capability to discriminate among odor samples according to the functional group of an odorant.

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

Molecularly Imprinted Nanomaterials for Sensor Applications

PubMed Central

Irshad, Muhammad; Iqbal, Naseer; Mujahid, Adnan; Afzal, Adeel; Hussain, Tajamal; Sharif, Ahsan; Ahmad, Ejaz; Athar, Muhammad Makshoof

2013-01-01

Molecular imprinting is a well-established technology to mimic antibody-antigen interaction in a synthetic platform. Molecularly imprinted polymers and nanomaterials usually possess outstanding recognition capabilities. Imprinted nanostructured materials are characterized by their small sizes, large reactive surface area and, most importantly, with rapid and specific analysis of analytes due to the formation of template driven recognition cavities within the matrix. The excellent recognition and selectivity offered by this class of materials towards a target analyte have found applications in many areas, such as separation science, analysis of organic pollutants in water, environmental analysis of trace gases, chemical or biological sensors, biochemical assays, fabricating artificial receptors, nanotechnology, etc. We present here a concise overview and recent developments in nanostructured imprinted materials with respect to various sensor systems, e.g., electrochemical, optical and mass sensitive, etc. Finally, in light of recent studies, we conclude the article with future perspectives and foreseen applications of imprinted nanomaterials in chemical sensors. PMID:28348356

The application of the statistical classifying models for signal evaluation of the gas sensors analyzing mold contamination of the building materials

NASA Astrophysics Data System (ADS)

Majerek, Dariusz; Guz, Łukasz; Suchorab, Zbigniew; Łagód, Grzegorz; Sobczuk, Henryk

2017-07-01

Mold that develops on moistened building barriers is a major cause of the Sick Building Syndrome (SBS). Fungal contamination is normally evaluated using standard biological methods which are time-consuming and require a lot of manual labor. Fungi emit Volatile Organic Compounds (VOC) that can be detected in the indoor air using several techniques of detection e.g. chromatography. VOCs can be also detected using gas sensors arrays. All array sensors generate particular voltage signals that ought to be analyzed using properly selected statistical methods of interpretation. This work is focused on the attempt to apply statistical classifying models in evaluation of signals from gas sensors matrix to analyze the air sampled from the headspace of various types of the building materials at different level of contamination but also clean reference materials.

An acetone microsensor with a ring oscillator circuit fabricated using the commercial 0.18 μm CMOS process.

PubMed

Yang, Ming-Zhi; Dai, Ching-Liang; Shih, Po-Jen

2014-07-17

This study investigates the fabrication and characterization of an acetone microsensor with a ring oscillator circuit using the commercial 0.18 μm complementary metal oxide semiconductor (CMOS) process. The acetone microsensor contains a sensitive material, interdigitated electrodes and a polysilicon heater. The sensitive material is α-Fe2O3 synthesized by the hydrothermal method. The sensor requires a post-process to remove the sacrificial oxide layer between the interdigitated electrodes and to coat the α-Fe2O3 on the electrodes. When the sensitive material adsorbs acetone vapor, the sensor produces a change in capacitance. The ring oscillator circuit converts the capacitance of the sensor into the oscillation frequency output. The experimental results show that the output frequency of the acetone sensor changes from 128 to 100 MHz as the acetone concentration increases 1 to 70 ppm.

An Acetone Microsensor with a Ring Oscillator Circuit Fabricated Using the Commercial 0.18 μm CMOS Process

PubMed Central

Yang, Ming-Zhi; Dai, Ching-Liang; Shih, Po-Jen

2014-01-01

This study investigates the fabrication and characterization of an acetone microsensor with a ring oscillator circuit using the commercial 0.18 μm complementary metal oxide semiconductor (CMOS) process. The acetone microsensor contains a sensitive material, interdigitated electrodes and a polysilicon heater. The sensitive material is α-Fe2O3 synthesized by the hydrothermal method. The sensor requires a post-process to remove the sacrificial oxide layer between the interdigitated electrodes and to coat the α-Fe2O3 on the electrodes. When the sensitive material adsorbs acetone vapor, the sensor produces a change in capacitance. The ring oscillator circuit converts the capacitance of the sensor into the oscillation frequency output. The experimental results show that the output frequency of the acetone sensor changes from 128 to 100 MHz as the acetone concentration increases 1 to 70 ppm. PMID:25036331

QCM gas phase detection with ceramic materials--VOCs and oil vapors.

PubMed

Latif, Usman; Rohrer, Andreas; Lieberzeit, Peter A; Dickert, Franz L

2011-06-01

Titanate sol-gel layers imprinted with carbonic acids were used as sensitive layers on quartz crystal microbalance. These functionalized ceramics enable us detection of volatile organic compounds such as ethanol, n-propanol, n-butanol, n-hexane, n-heptane, n-/iso-octane, and n-decane. Variation of the precursors (i.e., tetrabutoxy titanium, tetrapropoxy titanium, tetraethoxy titanium) allows us to tune the sensitivity of the material by a factor of 7. Sensitivity as a function of precursors leads to selective inclusion of n-butanol vapors down to 1 ppm. The selectivity of materials is optimized to differentiate between isomers, e.g., n- and iso-octane. The results can be rationalized by correlating the sensor effects of hydrocarbons with the Wiener index. A mass-sensitive sensor based on titanate layer was also developed for monitoring emanation of degraded engine oil. Heating the sensor by a meander avoids vapor condensation. Thus, a continuously working oil quality sensor was designed.

Aqueous Rechargeable Alkaline CoxNi2-xS2/TiO2 Battery.

PubMed

Liu, Jilei; Wang, Jin; Ku, Zhiliang; Wang, Huanhuan; Chen, Shi; Zhang, Lili; Lin, Jianyi; Shen, Ze Xiang

2016-01-26

An electrochemical energy storage system with high energy density, stringent safety, and reliability is highly desirable for next-generation energy storage devices. Here an aqueous rechargeable alkaline CoxNi2-xS2 // TiO2 battery system is designed by integrating two reversible electrode processes associated with OH(-) insertion/extraction in the cathode part and Li ion insertion/extraction in the anode part, respectively. The prototype CoxNi2-xS2 // TiO2 battery is able to deliver high energy/power densities of 83.7 Wh/kg at 609 W/kg (based on the total mass of active materials) and good cycling stabilities (capacity retention 75.2% after 1000 charge/discharge cycles). A maximum volumetric energy density of 21 Wh/l (based on the whole packaged cell) has been achieved, which is comparable to that of a thin-film battery and better than that of typical commercial supercapacitors, benefiting from the unique battery and hierarchical electrode design. This hybrid system would enrich the existing aqueous rechargeable LIB chemistry and be a promising battery technology for large-scale energy storage.

Stability of half-metallic behavior with lattice variation for Fe2-xCoxMnAl Heusler alloy

NASA Astrophysics Data System (ADS)

Jain, Vivek Kumar; Lakshmi, N.; Jain, Rakesh

2018-04-01

The electronic structure and magnetic properties with variation of lattice constant for Fe2-xCoxMnAl Heusler alloys have been studied. Total magnetic moments predicted by the Slater Pauling rule is maintained over a wide range of lattice variation for the series. Half metallic ferromagnetic nature with 100% spin polarization is observed for a lattice range from 5.40-5.70 Å, 5.35-5.55 Å, 5.30-5.60 Å and 5.25-5.55 Å respectively for x = 0.5, 1.0 1.5, 2.0. Due to the stability of half metallic character for a wide range of lattice parameters, these alloys are promising, robust materials suitable for spintronics device applications.

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.

Nonlinear estimation for arrays of chemical sensors

NASA Astrophysics Data System (ADS)

Yosinski, Jason; Paffenroth, Randy

2010-04-01

Reliable detection of hazardous materials is a fundamental requirement of any national security program. Such materials can take a wide range of forms including metals, radioisotopes, volatile organic compounds, and biological contaminants. In particular, detection of hazardous materials in highly challenging conditions - such as in cluttered ambient environments, where complex collections of analytes are present, and with sensors lacking specificity for the analytes of interest - is an important part of a robust security infrastructure. Sophisticated single sensor systems provide good specificity for a limited set of analytes but often have cumbersome hardware and environmental requirements. On the other hand, simple, broadly responsive sensors are easily fabricated and efficiently deployed, but such sensors individually have neither the specificity nor the selectivity to address analyte differentiation in challenging environments. However, arrays of broadly responsive sensors can provide much of the sensitivity and selectivity of sophisticated sensors but without the substantial hardware overhead. Unfortunately, arrays of simple sensors are not without their challenges - the selectivity of such arrays can only be realized if the data is first distilled using highly advanced signal processing algorithms. In this paper we will demonstrate how the use of powerful estimation algorithms, based on those commonly used within the target tracking community, can be extended to the chemical detection arena. Herein our focus is on algorithms that not only provide accurate estimates of the mixture of analytes in a sample, but also provide robust measures of ambiguity, such as covariances.

Millimeter Wave Sensor For On-Line Inspection Of Thin Sheet Dielectrics

DOEpatents

Bakhtiari, Sasan; Gopalsami, Nachappa; Raptis, Apostolos C.

1999-03-23

A millimeter wave sensor is provided for non-destructive inspection of thin sheet dielectric materials. The millimeter wave sensor includes a Gunn diode oscillator (GDO) source generating a mill meter wave electromagnetic energy signal having a single frequency. A heater is coupled to the GDO source for stabilizing the single frequency. A small size antenna is coupled to the GDO source for transmitting the millimeter wave electromagnetic energy signal to a sample material and for receiving a reflected millimeter wave electromagnetic energy signal from the sample material. Ferrite circulator isolators coupled between the GDO source and the antenna separate the millimeter wave electromagnetic energy signal into transmitted and received electromagnetic energy signal components and a detector detects change in both amplitude and phase of the transmitted and received electromagnetic energy signal components. A millimeter wave sensor is provided for non-destructive inspection of thin sheet dielectric materials. The millimeter wave sensor includes a Gunn diode oscillator (GDO) source generating a mill meter wave electromagnetic energy signal having a single frequency. A heater is coupled to the GDO source for stabilizing the single frequency. A small size antenna is coupled to the GDO source for transmitting the millimeter wave electromagnetic energy signal to a sample material and for receiving a reflected millimeter wave electromagnetic energy signal from the sample material. Ferrite circulator isolators coupled between the GDO source and the antenna separate the millimeter wave electromagnetic energy signal into transmitted and received electromagnetic energy signal components and a detector detects change in both amplitude and phase of the transmitted and received electromagnetic energy signal components.

Risk Identification in a Smart Monitoring System Used to Preserve Artefacts Based on Textile Materials

NASA Astrophysics Data System (ADS)

Diaconescu, V. D.; Scripcariu, L.; Mătăsaru, P. D.; Diaconescu, M. R.; Ignat, C. A.

2018-06-01

Exhibited textile-materials-based artefacts can be affected by the environmental conditions. A smart monitoring system that commands an adaptive automatic environment control system is proposed for indoor exhibition spaces containing various textile artefacts. All exhibited objects are monitored by many multi-sensor nodes containing temperature, relative humidity and light sensors. Data collected periodically from the entire sensor network is stored in a database and statistically processed in order to identify and classify the environment risk. Risk consequences are analyzed depending on the risk class and the smart system commands different control measures in order to stabilize the indoor environment conditions to the recommended values and prevent material degradation.

Nanostructured materials detect epidermal growth factor receptor, neuron specific enolase and carcinoembryonic antigen

NASA Astrophysics Data System (ADS)

Stefan-van Staden, Raluca-Ioana; Comnea-Stancu, Ionela Raluca; Surdu-Bob, Carmen Cristina; Badulescu, Marius

2015-09-01

New nanostructured materials based on thin films of Cu and Ni deposited on textile material (veil), as well as gold nanostructured microspheres were used for the design of new stochastic sensors. The stochastic sensors were able to detect simultaneously a panel of biomarkers comprising epidermal growth factor receptor, neuron specific enolase, and carcinoembryonic antigen from whole blood samples with high reliabilities - recovery tests higher than 97.00%, with a RSD (%) lower than 0.1%. The stochastic sensors had shown high sensitivities and low determination levels for the detection of the proposed panel of biomarkers making early detection of lung cancer possible by fast screening of whole blood.

The Development of Silicon Carbide Based Hydrogen and Hydrocarbon Sensors

NASA Technical Reports Server (NTRS)

Liu, Chung-Chiun

1994-01-01

Silicon carbide is a high temperature electronic material. Its potential for development of chemical sensors in a high temperature environment has not been explored. The objective of this study is to use silicon carbide as the substrate material for the construction of chemical sensors for high temperature applications. Sensors for the detection of hydrogen and hydrocarbon are developed in this program under the auspices of Lewis Research Center, NASA. Metal-semiconductor or metal-insulator-semiconductor structures are used in this development. Specifically, using palladium-silicon carbide Schottky diodes as gas sensors in the temperature range of 100 to 400 C are designed, fabricated and assessed. The effect of heat treatment on the Pd-SiC Schottky diode is examined. Operation of the sensors at 400 C demonstrate sensitivity of the sensor to hydrogen and hydrocarbons. Substantial progress has been made in this study and we believe that the Pd-SiC Schottky diode has potential as a hydrogen and hydrocarbon sensor over a wide range of temperatures. However, the long term stability and operational life of the sensor need to be assessed. This aspect is an important part of our future continuing investigation.

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.

Comparative VOCs sensing performance for conducting polymer and porphyrin functionalized carbon nanotubes based sensors

NASA Astrophysics Data System (ADS)

Datta, Kunal; Rushi, Arti; Ghosh, Prasanta; Shirsat, Mahendra

2018-05-01

We report sensors for detection of ethyl alcohol, a prominent volatile organic compound (VOC). Single walled carbon nanotubes were selected as main sensing backbone. As efficiency of sensor is dependent upon the choice of sensing materials, the performances of conducting polymer and porphyrin based sensors were compared. Chemiresistive sensing modality was adopted to observe the performance of sensors. It has been found that porphyrin based sensor shows higher affinity towards ethyl alcohol.

The Evolution of High Temperature Gas Sensors.

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

Garzon, F. H.; Brosha, E. L.; Mukundan, R.

2001-01-01

Gas sensor technology based on high temperature solid electrolytes is maturing rapidly. Recent advances in metal oxide catalysis and thin film materials science has enabled the design of new electrochemical sensors. We have demonstrated prototype amperometric oxygen sensors, nernstian potentiometric oxygen sensors that operate in high sulfur environments, and hydrocarbon and carbon monoxide sensing mixed potentials sensors. Many of these devices exhibit part per million sensitivities, response times on the order of seconds and excellent long-term stability.

Evaluation and Improvement of Eddy Current Position Sensors in Magnetically Suspended Flywheel Systems

NASA Technical Reports Server (NTRS)

Dever, Timothy P.; Palazzolo, Alan B.; Thomas, Erwin M., III; Jansen, Ralph H.; McLallin, Kerry (Technical Monitor); Soeder, James (Technical Monitor)

2001-01-01

Eddy current position sensor performance is evaluated for use in a high-speed flywheel development system. The flywheel utilizes a five axis active magnetic bearing system. The eddy current sensors are used for position feedback for the bearing controller. Measured characteristics include sensitivity to multiple target materials and susceptibility to noise from the magnetic bearings and from sensor-to-sensor crosstalk. Improvements in axial sensor configuration and techniques for noise reduction are described.

Macrophages From Irradiated Tumors Express Higher Levels of iNOS, Arginase-I and COX-2, and Promote Tumor Growth

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

Tsai, C.-S.; Graduate Institute of Clinical Medical Sciences, Chang Gung University, Taiwan; Chen, F.-H.

2007-06-01

Purpose: To investigate the effects of single and fractionated doses of radiation on tumors and tumor-associated macrophages (TAMs), and to elucidate the potential of TAMs to influence tumor growth. Methods and Materials: A murine prostate cell line, TRAMP-C1, was grown in C57Bl/6J mice to 4-mm tumor diameter and irradiated with either 25 Gy in a single dose, or 60 Gy in 15 fractions. The tumors were removed at the indicated times and assessed for a variety of markers related to TAM content, activation status, and function. Results: In tumors receiving a single radiation dose, arginase (Arg-I), and cycloxygenase-2 (COX-2) mRNAmore » expression increased as a small transient wave within 24 h and a larger persistent wave starting after 3 days. Inducible nitric oxide synthase (iNOS) mRNA was elevated only after 3 days and continued to increase up to 3 weeks. After fractionated irradiation, Arg-1 and COX-2 mRNA levels increased within 5 days, whereas iNOS was increased only after 10 fractions of irradiation had been given. Increased levels of Arg-I, COX-2, and, to a lesser extent, iNOS protein were found to associate with TAMs 1-2 weeks after tumor irradiation. Function of TAMs were compared by mixing them with TRAMP-C1 cells and injecting them into mice; TRAMP-C1 cells mixed with TAMs from irradiated tumors appeared earlier and grew significantly faster than those mixed with TAMs from unirradiated tumors or TRAMP-C1 alone. Conclusions: Tumor-associated macrophages in the postirradiated tumor microenvironment express higher levels of Arg-1, COX-2, and iNOS, and promote early tumor growth in vivo.« less

Integral window/photon beam position monitor and beam flux detectors for x-ray beams

DOEpatents

Shu, Deming; Kuzay, Tuncer M.

1995-01-01

A monitor/detector assembly in a synchrotron for either monitoring the position of a photon beam or detecting beam flux may additionally function as a vacuum barrier between the front end and downstream segment of the beamline in the synchrotron. A base flange of the monitor/detector assembly is formed of oxygen free copper with a central opening covered by a window foil that is fused thereon. The window foil is made of man-made materials, such as chemical vapor deposition diamond or cubic boron nitrate and in certain configurations includes a central opening through which the beams are transmitted. Sensors of low atomic number materials, such as aluminum or beryllium, are laid on the window foil. The configuration of the sensors on the window foil may be varied depending on the function to be performed. A contact plate of insulating material, such as aluminum oxide, is secured to the base flange and is thereby clamped against the sensor on the window foil. The sensor is coupled to external electronic signal processing devices via a gold or silver lead printed onto the contact plate and a copper post screw or alternatively via a copper screw and a copper spring that can be inserted through the contact plate and coupled to the sensors. In an alternate embodiment of the monitor/detector assembly, the sensors are sandwiched between the window foil of chemical vapor deposition diamond or cubic boron nitrate and a front foil made of similar material.

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

DOEpatents

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

1997-01-01

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

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

DOEpatents

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

1997-05-06

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

Design and build a compact Raman sensor for identification of chemical composition

NASA Astrophysics Data System (ADS)

Garcia, Christopher S.; Abedin, M. Nurul; Ismail, Syed; Sharma, Shiv K.; Misra, Anupam K.; Sandford, Stephen P.; Elsayed-Ali, Hani

2008-04-01

A compact remote Raman sensor system was developed at NASA Langley Research Center. This sensor is an improvement over the previously reported system, which consisted of a 532 nm pulsed laser, a 4-inch telescope, a spectrograph, and an intensified CCD camera. One of the attractive features of the previous system was its portability, thereby making it suitable for applications such as planetary surface explorations, homeland security and defense applications where a compact portable instrument is important. The new system was made more compact by replacing bulky components with smaller and lighter components. The new compact system uses a smaller spectrograph measuring 9 x 4 x 4 in. and a smaller intensified CCD camera measuring 5 in. long and 2 in. in diameter. The previous system was used to obtain the Raman spectra of several materials that are important to defense and security applications. Furthermore, the new compact Raman sensor system is used to obtain the Raman spectra of a diverse set of materials to demonstrate the sensor system's potential use in the identification of unknown materials.

New type of eddy current sensor for large-displacement test

NASA Astrophysics Data System (ADS)

Pan, Haifeng; Zhu, Huizhong; Fu, Zhibin; Xu, Yuzheng; Feng, Guanping

2001-09-01

In this paper a new type of large displacement eddy current sensor is developed to overcome the three main disadvantages of the traditional eddy current senor. For a traditional sensor, the measurement range is limited and less than one half of the diameter of the measuring coil. The output is high sensitivity to the changes of the target material and the cable length connected between the probe and the preamplifier. When the material or the cable length changed, it is necessary to readjust the preamplifier. The probe of the new eddy current sensor has three coaxial measuring coils, one is an exciting coil and the other two are receiving coils. The diameter of measuring coils is (Phi) 11 mm. The measurement range of this sensor is 40mm and almost four times of the diameter of the coil. The form of differential input and feedback amplification is used in signal amplifier. Thus the effect of the common modules, such as the changes of the target material and the cable length, can be counteracted well.

Development of electronic tattoo for pulse rate monitoring: Materials perspective

NASA Astrophysics Data System (ADS)

Shinde, Shilpa Vikas; Sonavane, S. S.

2018-05-01

In India, there is a growing concern of the heart diseases and deaths due to heart failure. The severity of the problem can be minimised by efficient heart rate monitoring which can be used to provide before time caution to cater heart attack. Wearable sensor can be designed to sense the pulse. The sensor can be either placed near to heart or on the wrist to sense pulses and send pulse signals to the doctors. Such sensor should adhere to the skin for sufficiently long period without causing etching to the patient. It should also be bendable and stretchable like skin. This paper is a part of the research work carried out to develop patch type sensor, which is termed as Electronic Tattoo (ET). In pursuit for development of ET, we came across various designs and candidate materials which can be used for the ET. Thus, in this paper, we describe the process of selecting best suited method and material for the ET. It may also be noted that the sensor development is governed by the prevailing IEEE 802.15.6 standard.

Integrated polymer-based Mach-Zehnder interferometer label-free streptavidin biosensor compatible with injection molding.

PubMed

Bruck, R; Melnik, E; Muellner, P; Hainberger, R; Lämmerhofer, M

2011-05-15

We report the development of a Mach-Zehnder interferometer biosensor based on a high index contrast polymer material system and the demonstration of label-free online measurement of biotin-streptavidin binding on the sensor surface. The surface of the polyimide waveguide core layer was functionalized with 3-mercaptopropyl trimethoxy silane and malemide tagged biotin. Several concentrations of Chromeon 642-streptavidin dissolved in phosphate buffered saline solution were rinsed over the functionalized sensor surface by means of a fluidic system and the biotin-streptavidin binding process was observed in the output signal of the interferometer at a wavelength of 1310 nm. Despite the large wavelength and the comparatively low surface sensitivity of the sensor system due to the low index contrast in polymer material systems compared to inorganic material systems, we were able to resolve streptavidin concentrations of down to 0.1 μg/ml. The polymer-based optical sensor design is fully compatible with cost-efficient mass production technologies such as injection molding and spin coating, which makes it an attractive alternative to inorganic optical sensors. Copyright © 2011 Elsevier B.V. All rights reserved.

Design and Build a Compact Raman Sensor for Identification of Chemical Composition

NASA Technical Reports Server (NTRS)

Garcia, Christopher S.; Abedin, M. Nurul; Ismail, Syed; Sharma, Shiv K.; Misra, Anupam K.; Sandford, Stephen P.; Elsayed-Ali, Hani

2008-01-01

A compact remote Raman sensor system was developed at NASA Langley Research Center. This sensor is an improvement over the previously reported system, which consisted of a 532 nm pulsed laser, a 4-inch telescope, a spectrograph, and an intensified charge-coupled devices (CCD) camera. One of the attractive features of the previous system was its portability, thereby making it suitable for applications such as planetary surface explorations, homeland security and defense applications where a compact portable instrument is important. The new system was made more compact by replacing bulky components with smaller and lighter components. The new compact system uses a smaller spectrograph measuring 9 x 4 x 4 in. and a smaller intensified CCD camera measuring 5 in. long and 2 in. in diameter. The previous system was used to obtain the Raman spectra of several materials that are important to defense and security applications. Furthermore, the new compact Raman sensor system is used to obtain the Raman spectra of a diverse set of materials to demonstrate the sensor system's potential use in the identification of unknown materials.

Thin Film Ceramic Strain Sensor Development for Harsh Environments: Interim Report on Identification of Candidate Thin Film Ceramics to Test for Viability for Static Strain Sensor Development

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Fralick, Gustave C.; Hunter, Gary W.

2006-01-01

The need to consider ceramic sensing elements is brought about by the temperature limits of metal thin film sensors in propulsion system applications. In order to have a more passive method of negating changes of resistance due to temperature, an effort is underway at NASA Glenn to develop high temperature thin film ceramic static strain gauges for application in turbine engines, specifically in the fan and compressor modules on blades. Other applications can be on aircraft hot section structures and on thermal protection systems. The near-term interim goal of the research effort was to identify candidate thin film ceramic sensor materials to test for viability and provide a list of possible thin film ceramic sensor materials and corresponding properties to test for viability. This goal was achieved by a thorough literature search for ceramics that have the potential for application as high temperature thin film strain gauges, reviewing potential candidate materials for chemical and physical compatibility with our microfabrication procedures and substrates.

Thin Film Ceramic Strain Sensor Development for Harsh Environments: Identification of Candidate Thin Film Ceramics to Test for Viability for Static Strain Sensor Development

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Fralick, Gustave C.; Hunter, Gary W.

2006-01-01

The need to consider ceramic sensing elements is brought about by the temperature limits of metal thin film sensors in propulsion system applications. In order to have a more passive method of negating changes of resistance due to temperature, an effort is underway at NASA GRC to develop high temperature thin film ceramic static strain gauges for application in turbine engines, specifically in the fan and compressor modules on blades. Other applications include on aircraft hot section structures and on thermal protection systems. The near-term interim goal of this research effort was to identify candidate thin film ceramic sensor materials to test for viability and provide a list of possible thin film ceramic sensor materials and corresponding properties to test for viability. This goal was achieved by a thorough literature search for ceramics that have the potential for application as high temperature thin film strain gauges, reviewing potential candidate materials for chemical & physical compatibility with NASA GRC's microfabrication procedures and substrates.

Microwave bio-sensor based on symmetrical split ring resonator with spurline filters for therapeutic goods detection.

PubMed

Alahnomi, Rammah A; Zakaria, Z; Ruslan, E; Ab Rashid, S R; Mohd Bahar, Amyrul Azuan; Shaaban, Azizah

2017-01-01

A novel symmetrical split ring resonator (SSRR) based microwave sensor with spurline filters for detecting and characterizing the properties of solid materials has been developed. Due to the weak perturbation in the interaction of material under test (MUT) and planar microwave sensor, spurline filters were embedded to the SSRR microwave sensor which effectively enhanced Q-factor with suppressing the undesired harmonic frequency. The spurline filter structures force the presented sensor to resonate at a fundamental frequency of 2.2 GHz with the capabilities of suppressing rejected harmonic frequency and miniaturization in circuit size. A wide bandwidth rejection is achieved by using double spurlines filters with high Q-factor achievement (up to 652.94) compared to single spurline filter. The new SSRR sensor with spurline filters displayed desired properties such as high sensitivity, accuracy, and performance with a 1.3% typical percentage error in the measurement results. Furthermore, the sensor has been successfully applied for detecting and characterizing solid materials (such as Roger 5880, Roger 4350, and FR4) and evidently demonstrated that it can suppress the harmonic frequency effectively. This novel design with harmonic suppression is useful for various applications such as food industry (meat, fruit, vegetables), biological medicine (derived from proteins and other substances produced by the body), and Therapeutic goods (antiseptics, vitamins, anti-psychotics, and other medicines).

Microwave bio-sensor based on symmetrical split ring resonator with spurline filters for therapeutic goods detection

PubMed Central

Ruslan, E.; Ab Rashid, S. R.; Mohd Bahar, Amyrul Azuan; Shaaban, Azizah

2017-01-01

A novel symmetrical split ring resonator (SSRR) based microwave sensor with spurline filters for detecting and characterizing the properties of solid materials has been developed. Due to the weak perturbation in the interaction of material under test (MUT) and planar microwave sensor, spurline filters were embedded to the SSRR microwave sensor which effectively enhanced Q-factor with suppressing the undesired harmonic frequency. The spurline filter structures force the presented sensor to resonate at a fundamental frequency of 2.2 GHz with the capabilities of suppressing rejected harmonic frequency and miniaturization in circuit size. A wide bandwidth rejection is achieved by using double spurlines filters with high Q-factor achievement (up to 652.94) compared to single spurline filter. The new SSRR sensor with spurline filters displayed desired properties such as high sensitivity, accuracy, and performance with a 1.3% typical percentage error in the measurement results. Furthermore, the sensor has been successfully applied for detecting and characterizing solid materials (such as Roger 5880, Roger 4350, and FR4) and evidently demonstrated that it can suppress the harmonic frequency effectively. This novel design with harmonic suppression is useful for various applications such as food industry (meat, fruit, vegetables), biological medicine (derived from proteins and other substances produced by the body), and Therapeutic goods (antiseptics, vitamins, anti-psychotics, and other medicines). PMID:28934301

Construction of a Polyaniline Nanofiber Gas Sensor

ERIC Educational Resources Information Center

Virji, Shabnam; Weiller, Bruce H.; Huang, Jiaxing; Blair, Richard; Shepherd, Heather; Faltens, Tanya; Haussmann, Philip C.; Kaner, Richard B.; Tolbert, Sarah H.

2008-01-01

The electrical properties of polyaniline changes by orders of magnitude upon exposure to analytes such as acids or bases, making it a useful material for detection of these analytes in the gas phase. The objectives of this lab are to synthesize different diameter polyaniline nanofibers and compare them as sensor materials. In this experiment…

Making and Using a Sensing Polymeric Material for Cu[superscript 2+

ERIC Educational Resources Information Center

Paddock, Jean R.; Maghasi, Anne T.; Heineman, William R.; Seliskar, Carl J.

2005-01-01

A simple chemical sensor-related experiment rooted in the synthesis of polymeric materials for use in either an advanced high-school or undergraduate college laboratory is presented. Students are introduced to and combine to the concepts of the chemical sensor, polymer chemistry, spectroscopy, metal chelates, and quantitative analytical methods.

Means for ultrasonic testing when material properties vary

DOEpatents

Beller, Laurence S.

1979-01-01

A device is provided for maintaining constant sensitivity in an ultrasonic testing device, despite varying attenuation due to the properties of the material being tested. The device includes a sensor transducer for transmitting and receiving a test signal and a monitor transducer positioned so as to receive ultrasonic energy transmitted through the material to be tested. The received signal of the monitor transducer is utilized in analyzing data obtained from the sensor transducer.

Improved Ion-Channel Biosensors

NASA Technical Reports Server (NTRS)

Nadeau, Jay; White, Victor; Dougherty, Dennis; Maurer, Joshua

2004-01-01

An effort is underway to develop improved biosensors of a type based on ion channels in biomimetic membranes. These sensors are microfabricated from silicon and other materials compatible with silicon. As described, these sensors offer a number of advantages over prior sensors of this type.

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.

Frequency scanning capaciflector for capacitively determining the material properties

NASA Technical Reports Server (NTRS)

Campbell, Charles E. (Inventor)

1996-01-01

A capaciflector sensor system scanned in frequency is used to detect the permittivity of the material of an object being sensed. A capaciflector sensor element, coupled to current-measuring voltage follower circuitry, is driven by a frequency swept oscillator and generates an output which corresponds to capacity as a function of the input frequency. This swept frequency information is fed into apparatus e.g. a digital computer for comparing the shape of the capacitance vs. frequency curve against characteristic capacitor vs. frequency curves for a variety of different materials which are stored, for example, in a digital memory of the computer or a database. Using a technique of pattern matching, a determination is made as to the identification of the material. Also, when desirable, the distance between the sensor and the object can be determined.

Research on the conductivity of a haptic sensor, especially with the sensor under extended condition

NASA Astrophysics Data System (ADS)

Zheng, Yaoyang; Shimada, Kunio

2008-11-01

The present paper describes the application of magnetic compound fluid (MCF) rubber as a haptic sensor for use as a material for robot sensors, artificial skin, and so on. MCF rubber is one of several new composite materials utilizing the MCF magnetic responsive fluid developed by Shimada. By applying MCF to silicon oil rubber, we can make MCF rubber highly sensitive to temperature and electric conduction. By mixing Cu and Ni particles in the silicon oil rubber and then applying a strong magnetic field, we can produce magnetic clusters at high density. The clusters form a network, as confirmed by optical observation. The MCF rubber with small deformations can act as an effective sensor. We report herein several experiments in which changes in the MCF rubber's resistance were observed when the rubber was compressed and a deformation was generated. We then made a trial haptic sensor using the MCF conductive rubber and performed many experiments to observe changes in the electrical resistance of the sensor. The experimental results showed that the proposed sensor made with MCF conductive rubber is useful for sensing small amounts of pressure or small deformations. Sometimes, however, the sensor rubber will be extended when we apply this sensor to the finger of the robot or an elbow. In these cases, it is necessary to understand the changes in sensor's conductivity. We therefore carried out some experiments to demonstrate how, under tensile conditions, the sensor's conductivity changes to a small value easier than the sensor in free condition. The results show that the sensors became more sensitive to the same pressure under extended conditions. In the present paper, we first describe the new type of functional fluid MCF rubber and a new composite material based on this MCF fluid. We then explain the production method for MCF conductive rubber and its conductive algorithm. Finally, we report our results regarding the MCF sensitivity when the MCF rubber was pulled. These experiments show an improvement in the sensitivity of the MCF rubber in the extended state.

Impact of Isolation and Immobilization Layers on the Electro-Mechanical Response of Piezoresistive Nano Cantilever Sensors.

PubMed

Mathew, Ribu; Sankar, A Ravi

2018-03-01

In the last decade, piezoresistive nano cantilever sensors have been extensively explored, especially for chemical and biological sensing applications. Piezoresistive cantilever sensors are multi-layer structures with different constituent materials. Performance of such sensors is a function of their geometry and constituent materials. For a fixed material set, the pre-requisite for optimizing the performance of a composite piezoresistive cantilever sensor is careful geometrical design of its constituent layers. Even though, treatise encompasses various designs of such sensors, typically for computational simplicity the functional layers i.e., the isolation and immobilization layers are neglected in the modeling stages. In this paper, we elucidate the impact of the functional layers on the electro-mechanical response of composite piezoresistive nano cantilever sensors. Systematic and detailed computations are performed using theoretical models and numerical simulations. Results show that both the isolation and immobilization layers play a critical role in governing the sensor performance. Simulation results depict that compared to a sensor with an isolation layer of thickness 100 nm, a sensor without isolation layer has 36.29% and 42.51% better deflection sensitivity and electrical sensitivity respectively. Furthermore, it is found that when an immobilization layer of thickness 40 nm is added atop the isolation layer, the deflection sensitivity and electrical sensitivity reduces by 12.98% and 15.83% respectively. Through our investigation it is shown that the isolation and immobilization layers not only play a vital role in determining the stability and electro-mechanical response of the sensor but their negligence in the design stages can be detrimental. Apart from investigating the impact of the immobilization layer thickness, to model the sensor closer to real time operational conditions, we have performed analysis to understand the impact of non-uniformity in the immobilization layer thickness and non-uniform surface stress loading on the electro-mechanical response of the sensor. Results and inferences obtained from this study will help NEMS engineers to optimize the performance of piezoresistive nano cantilever sensors and to design multi-layer cantilever platform structures for other transducers.

Biomaterial based sulphur di oxide gas sensor

NASA Astrophysics Data System (ADS)

Ghosh, P. K.; Sarkar, A.

2013-06-01

Biomaterials are getting importance in the present research field of sensors. In this present paper performance of biomaterial based gas sensor made of gum Arabica and garlic extract had been studied. Extract of garlic clove with multiple medicinal and chemical utility can be proved to be useful in sensing Sulphur di Oxide gas. On exposure to Sulphur di Oxide gas the material under observation suffers some temporary structural change, which can be observed in form of amplified potentiometric change through simple electronic circuitry. Exploiting this very property a potentiometric gas sensor of faster response and recovery time can be designed. In this work sensing property of the said material has been studied through DC conductance, FTIR spectrum etc.

SansEC Sensing Technology - A New Tool for Designing Space Systems and Components

NASA Technical Reports Server (NTRS)

Woodard, Stanley E.

2011-01-01

This paper presents concepts for using the NASA developed SansEC sensing technology for reconfiguring/modifying many space subsystems to add to their original function the ability to be sensors/sensor arrays without the addition of the electrical circuitry typically used for sensors. Each sensor is a self-resonating planar pattern of electrically conductive material that is an open-circuit single component without electrical connections. The sensors are wirelessly powered using external oscillating magnetic fields and when electrically excited respond with their own magnetic fields whose frequency, amplitude and bandwidth can be correlated with the magnitude of multiple unrelated physical quantities. These sensors have been demonstrated for numerous measurements required for spacecraft and inflatable/expandable structures. SansEC sensors are damage resilient and simple to fabricate. Thin films of conductive material can be used to create sensor arrays that function as sensing skins. Each sensor on the skin can be tailored for a science or engineering measurement. Additionally, each sensor has an inherent damage detection capability. These sensing skins can be used to redesign inflatable habitat multi-layer insulation to provide additional functions of environmental measurement and micrometeorite/orbital debris damage detections. The sensing skins can be deposited on planetary exploratory vehicles to increase the number of measurements with negligible weight increase.

Improved response time of flexible microelectromechanical sensors employing eco-friendly nanomaterials.

PubMed

Fan, Shicheng; Dan, Li; Meng, Lingju; Zheng, Wei; Elias, Anastasia; Wang, Xihua

2017-11-09

Flexible force/pressure sensors are of interest for academia and industry and have applications in wearable technologies. Most of such sensors on the market or reported in journal publications are based on the operation mechanism of probing capacitance or resistance changes of the materials under pressure. Recently, we reported the microelectromechanical (MEM) sensors based on a different mechanism: mechanical switches. Multiples of such MEM sensors can be integrated to achieve the same function of regular force/pressure sensors while having the advantages of ease of fabrication and long-term stability in operation. Herein, we report the dramatically improved response time (more than one order of magnitude) of these MEM sensors by employing eco-friendly nanomaterials-cellulose nanocrystals. For instance, the incorporation of polydimethysiloxane filled with cellulose nanocrystals shortened the response time of MEM sensors from sub-seconds to several milliseconds, leading to the detection of both diastolic and systolic pressures in the radial arterial blood pressure measurement. Comprehensive mechanical and electrical characterization of the materials and the devices reveal that greatly enhanced storage modulus and loss modulus play key roles in this improved response time. The demonstrated fast-response flexible sensors enabled continuous monitoring of heart rate and complex cardiovascular signals using pressure sensors for future wearable sensing platforms.

Open Circuit Resonant (SansEC) Sensor for Composite Damage Detection and Diagnosis in Aircraft Lightning Environments

NASA Technical Reports Server (NTRS)

Wang, Chuantong; Dudley, Kenneth L.; Szatkowski, George N.

2012-01-01

Composite materials are increasingly used in modern aircraft for reducing weight, improving fuel efficiency, and enhancing the overall design, performance, and manufacturability of airborne vehicles. Materials such as fiberglass reinforced composites (FRC) and carbon-fiber-reinforced polymers (CFRP) are being used to great advantage in airframes, wings, engine nacelles, turbine blades, fairings, fuselage and empennage structures, control surfaces and coverings. However, the potential damage from the direct and indirect effects of lightning strikes is of increased concern to aircraft designers and operators. When a lightning strike occurs, the points of attachment and detachment on the aircraft surface must be found by visual inspection, and then assessed for damage by maintenance personnel to ensure continued safe flight operations. In this paper, a new method and system for aircraft in-situ damage detection and diagnosis are presented. The method and system are based on open circuit (SansEC) sensor technology developed at NASA Langley Research Center. SansEC (Sans Electric Connection) sensor technology is a new technical framework for designing, powering, and interrogating sensors to detect damage in composite materials. Damage in composite material is generally associated with a localized change in material permittivity and/or conductivity. These changes are sensed using SansEC. Unique electrical signatures are used for damage detection and diagnosis. NASA LaRC has both experimentally and theoretically demonstrated that SansEC sensors can be effectively used for in-situ composite damage detection.

Tactile-Sensing Based on Flexible PVDF Nanofibers via Electrospinning: A Review

PubMed Central

Wang, Xiaomei; Sun, Fazhe; Yin, Guangchao; Wang, Yuting; Liu, Bo

2018-01-01

The flexible tactile sensor has attracted widespread attention because of its great flexibility, high sensitivity, and large workable range. It can be integrated into clothing, electronic skin, or mounted on to human skin. Various nanostructured materials and nanocomposites with high flexibility and electrical performance have been widely utilized as functional materials in flexible tactile sensors. Polymer nanomaterials, representing the most promising materials, especially polyvinylidene fluoride (PVDF), PVDF co-polymer and their nanocomposites with ultra-sensitivity, high deformability, outstanding chemical resistance, high thermal stability and low permittivity, can meet the flexibility requirements for dynamic tactile sensing in wearable electronics. Electrospinning has been recognized as an excellent straightforward and versatile technique for preparing nanofiber materials. This review will present a brief overview of the recent advances in PVDF nanofibers by electrospinning for flexible tactile sensor applications. PVDF, PVDF co-polymers and their nanocomposites have been successfully formed as ultrafine nanofibers, even as randomly oriented PVDF nanofibers by electrospinning. These nanofibers used as the functional layers in flexible tactile sensors have been reviewed briefly in this paper. The β-phase content, which is the strongest polar moment contributing to piezoelectric properties among all the crystalline phases of PVDF, can be improved by adjusting the technical parameters in electrospun PVDF process. The piezoelectric properties and the sensibility for the pressure sensor are improved greatly when the PVDF fibers become more oriented. The tactile performance of PVDF composite nanofibers can be further promoted by doping with nanofillers and nanoclay. Electrospun P(VDF-TrFE) nanofiber mats used for the 3D pressure sensor achieved excellent sensitivity, even at 0.1 Pa. The most significant enhancement is that the aligned electrospun core-shell P(VDF-TrFE) nanofibers exhibited almost 40 times higher sensitivity than that of pressure sensor based on thin-film PVDF. PMID:29364175

Flexible Graphene-Based Wearable Gas and Chemical Sensors.

PubMed

Singh, Eric; Meyyappan, M; Nalwa, Hari Singh

2017-10-11

Wearable electronics is expected to be one of the most active research areas in the next decade; therefore, nanomaterials possessing high carrier mobility, optical transparency, mechanical robustness and flexibility, lightweight, and environmental stability will be in immense demand. Graphene is one of the nanomaterials that fulfill all these requirements, along with other inherently unique properties and convenience to fabricate into different morphological nanostructures, from atomically thin single layers to nanoribbons. Graphene-based materials have also been investigated in sensor technologies, from chemical sensing to detection of cancer biomarkers. The progress of graphene-based flexible gas and chemical sensors in terms of material preparation, sensor fabrication, and their performance are reviewed here. The article provides a brief introduction to graphene-based materials and their potential applications in flexible and stretchable wearable electronic devices. The role of graphene in fabricating flexible gas sensors for the detection of various hazardous gases, including nitrogen dioxide (NO 2 ), ammonia (NH 3 ), hydrogen (H 2 ), hydrogen sulfide (H 2 S), carbon dioxide (CO 2 ), sulfur dioxide (SO 2 ), and humidity in wearable technology, is discussed. In addition, applications of graphene-based materials are also summarized in detecting toxic heavy metal ions (Cd, Hg, Pb, Cr, Fe, Ni, Co, Cu, Ag), and volatile organic compounds (VOCs) including nitrobenzene, toluene, acetone, formaldehyde, amines, phenols, bisphenol A (BPA), explosives, chemical warfare agents, and environmental pollutants. The sensitivity, selectivity and strategies for excluding interferents are also discussed for graphene-based gas and chemical sensors. The challenges for developing future generation of flexible and stretchable sensors for wearable technology that would be usable for the Internet of Things (IoT) are also highlighted.

Gas Sensor Evaluations in Polymer Combustion Product Atmospheres

NASA Technical Reports Server (NTRS)

Delgado, Rafael H.; Davis, Dennis D.; Beeson, Harold D.

1999-01-01

Toxic gases produced by the combustion or thermo-oxidative degradation of materials such as wire insulation, foam, plastics, or electronic circuit boards in space shuttle or space station crew cabins may pose a significant hazard to the flight crew. Toxic gas sensors are routinely evaluated in pure gas standard mixtures, but the possible interferences from polymer combustion products are not routinely evaluated. The NASA White Sands Test Facility (WSTF) has developed a test system that provides atmospheres containing predetermined quantities of target gases combined with the coincidental combustion products of common spacecraft materials. The target gases are quantitated in real time by infrared (IR) spectroscopy and verified by grab samples. The sensor responses are recorded in real time and are compared to the IR and validation analyses. Target gases such as carbon monoxide, hydrogen cyanide, hydrogen chloride, and hydrogen fluoride can be generated by the combustion of poly(vinyl chloride), polyimide-fluoropolymer wire insulation, polyurethane foam, or electronic circuit board materials. The kinetics and product identifications for the combustion of the various materials were determined by thermogravimetric-IR spectroscopic studies. These data were then scaled to provide the required levels of target gases in the sensor evaluation system. Multisensor toxic gas monitors from two manufacturers were evaluated using this system. In general, the sensor responses satisfactorily tracked the real-time concentrations of toxic gases in a dynamic mixture. Interferences from a number of organic combustion products including acetaldehyde and bisphenol-A were minimal. Hydrogen bromide in the products of circuit board combustion registered as hydrogen chloride. The use of actual polymer combustion atmospheres for the evaluation of sensors can provide additional confidence in the reliability of the sensor response.

Error Analysis of Clay-Rock Water Content Estimation with Broadband High-Frequency Electromagnetic Sensors--Air Gap Effect.

PubMed

Bore, Thierry; Wagner, Norman; Lesoille, Sylvie Delepine; Taillade, Frederic; Six, Gonzague; Daout, Franck; Placko, Dominique

2016-04-18

Broadband electromagnetic frequency or time domain sensor techniques present high potential for quantitative water content monitoring in porous media. Prior to in situ application, the impact of the relationship between the broadband electromagnetic properties of the porous material (clay-rock) and the water content on the frequency or time domain sensor response is required. For this purpose, dielectric properties of intact clay rock samples experimental determined in the frequency range from 1 MHz to 10 GHz were used as input data in 3-D numerical frequency domain finite element field calculations to model the one port broadband frequency or time domain transfer function for a three rods based sensor embedded in the clay-rock. The sensor response in terms of the reflection factor was analyzed in time domain with classical travel time analysis in combination with an empirical model according to Topp equation, as well as the theoretical Lichtenecker and Rother model (LRM) to estimate the volumetric water content. The mixture equation considering the appropriate porosity of the investigated material provide a practical and efficient approach for water content estimation based on classical travel time analysis with the onset-method. The inflection method is not recommended for water content estimation in electrical dispersive and absorptive material. Moreover, the results clearly indicate that effects due to coupling of the sensor to the material cannot be neglected. Coupling problems caused by an air gap lead to dramatic effects on water content estimation, even for submillimeter gaps. Thus, the quantitative determination of the in situ water content requires careful sensor installation in order to reach a perfect probe clay rock coupling.

PREFACE: 5th International Conference on Materials and Applications for Sensors and Transducers (IC-MAST2015)

NASA Astrophysics Data System (ADS)

Hristoforou, E.; Vlachos, D. S.; Giouroudi, I.; Kar-Narayan, S.; Potirakis, S.

2016-03-01

The 5th International Conference on Materials and Applications for Sensors and Transducers, Mykonos island, Greece, hosted about 110 oral and poster papers and more than 90 participants. IC-MAS, as an international annual conference which tries to meet the needs for various types of sensors, particularly those which may be manufactured by low cost methods (i.e. hybrid sensors, smart specialization devices, particular applications not necessarily requiring integrated micro-nano technologies), covering all types of materials and physical effects, appears to be a necessity. IC-MAST has been established as a high quality international conference by: I. Gathering together multinational researchers from all over the world, working in different materials for sensors and transducers and technical applications of sensors, but also in some cases in the management of the data coming from sensors and transducers. The careful selection of the conference place (like Aegean Sea, Budapest, Prague, Bilbao, Mykonos etc) allows for enjoying the local hospitality and sightseeing. II. Emphasizing in hybrid sensors and smart specialization devices produced by inexpensive methods, without excluding of course micro-nano technology, from all kinds of solid state, liquid and gaseous materials, as well as in particular transducer applications (design and development, as well as use of sensing data) III. Innovatively implementing the Virtual Paper Concept, allowing for large impact of research works presented in the conference by authors who either have no time or no funding support for visiting a conference; this year more than 12 virtual papers are presented in the 5th IC MAST, following a standardized procedure via the our robust and reliable Conference Site (www.icmast.net!) > IV. Allowing for lengthy technical and managerial discussions in terms of sensor, material and instrumentation development; furthermore, the different research groups gathered together are offered the particular advantage of arranging and concluding research proposals and projects, otherwise not having a visible possibility of such realization The 5th IC-MAST organizing committee is proud that the Conference Keynote Speaker was Prof George Hadjipanayis, University of Delaware. We are also proud for the invited speakers of the conference: • Stergios Logothetidis, Aristotle University of Thessaloniki, Greece • Dimitris Tsoukalas, National Technical University of Athens, Greece • Susana Cardoso de Freitas, INESC Microsistemas e Nanotecnologias • Yuris Dzenis, University of Nebraska-Lincoln, USA The IC-MAST 2015 organizers believe that the target of the Conference has been successfully met by enhancing knowledge in sensors by all participants, accelerating the achievement of results and optimizing the under design products, in a quite friendly way! Therefore, participants made an appointment for the next year in Athens, Greece, where the 6th International MAST Conference will be realized!

Cobalt ferrite based magnetostrictive materials for magnetic stress sensor and actuator applications

NASA Technical Reports Server (NTRS)

Jiles, David C. (Inventor); Paulsen, Jason A. (Inventor); Snyder, John E. (Inventor); Lo, Chester C. H. (Inventor); Ring, Andrew P. (Inventor); Bormann, Keith A. (Inventor)

2008-01-01

Magnetostrictive material based on cobalt ferrite is described. The cobalt ferrite is substituted with transition metals (such manganese (Mn), chromium (Cr), zinc (Zn) and copper (Cu) or mixtures thereof) by substituting the transition metals for iron or cobalt to form substituted cobalt ferrite that provides mechanical properties that make the substituted cobalt ferrite material effective for use as sensors and actuators. The substitution of transition metals lowers the Curie temperature of the material (as compared to cobalt ferrite) while maintaining a suitable magnetostriction for stress sensing applications.

Metal/Metal Oxide Differential Electrode pH Sensors

NASA Technical Reports Server (NTRS)

West, William; Buehler, Martin; Keymeulen, Didier

2007-01-01

Solid-state electrochemical sensors for measuring the degrees of acidity or alkalinity (in terms of pH values) of liquid solutions are being developed. These sensors are intended to supplant older electrochemical pH sensors that include glass electrode structures and reference solutions. The older sensors are fragile and subject to drift. The present developmental solid-state sensors are more rugged and are expected to be usable in harsh environments. The present sensors are based on a differential-electrode measurement principle. Each sensor includes two electrodes, made of different materials, in equilibrium with the solution of interest.

Ammonia vapor sensing properties of polyaniline-titanium(IV)phosphate cation exchange nanocomposite.

PubMed

Khan, Asif Ali; Baig, Umair; Khalid, Mohd

2011-02-28

In this study, the electrically conducting polyaniline-titanium(IV)phosphate (PANI-TiP) cation exchange nanocomposite was synthesized by sol-gel method. The cation exchange nanocomposite based sensor for detection of ammonia vapors was developed at room temperature. It was revealed that the sensor showed good reversible response towards ammonia vapors ranging from 3 to 6%. It was found that the sensor with p-toluene sulphonic acid (p-TSA) doped exhibited higher sensing response than hydrochloric acid doped. This sensor has detection limit ≤1% ammonia. The response of resistivity changes of the cation exchange nanocomposite on exposure to different concentrations of ammonia vapors shows its utility as a sensing material. These studies suggest that the cation exchange nanocomposite could be a good material for ammonia sensor at room temperature. Copyright © 2010 Elsevier B.V. All rights reserved.

Multispectral image fusion for detecting land mines

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

Clark, G.A.; Sengupta, S.K.; Aimonetti, W.D.

1995-04-01

This report details a system which fuses information contained in registered images from multiple sensors to reduce the effects of clutter and improve the ability to detect surface and buried land mines. The sensor suite currently consists of a camera that acquires images in six bands (400nm, 500nm, 600nm, 700nm, 800nm and 900nm). Past research has shown that it is extremely difficult to distinguish land mines from background clutter in images obtained from a single sensor. It is hypothesized, however, that information fused from a suite of various sensors is likely to provide better detection reliability, because the suite ofmore » sensors detects a variety of physical properties that are more separable in feature space. The materials surrounding the mines can include natural materials (soil, rocks, foliage, water, etc.) and some artifacts.« less

Method and Apparatus for Non-Destructive Evaluation of Materials

NASA Technical Reports Server (NTRS)

Washabaugh, Andrew P. (Inventor); Lyons, Robert (Inventor); Thomas, Zachary (Inventor); Martin, Christopher (Inventor); Goldfine, Neil J. (Inventor)

2017-01-01

Methods and apparatus for characterizing composite materials for manufacturing quality assurance (QA), periodic inspection during the useful life, or for forensic analysis/material testing. System are provided that relate eddy-current sensor responses to the fiber layup of a composite structure, the presence of impact damage on a composite structure with or without a metal liner, volumetric stress within the composite, fiber tow density, and other NDE inspection requirements. Also provided are systems that determine electromagnetic material properties and material dimensions of composite materials from capacitive sensor inspection measurements. These properties are related to the presence of buried defects in non-conductive composite materials, moisture ingress, aging of the material due to service or environmental/thermal exposure, or changes in manufacturing quality.

Method and Apparatus for Non-Destructive Evaluation of Materials

NASA Technical Reports Server (NTRS)

Lyons, Robert (Inventor); Martin, Christopher (Inventor); Washabaugh, Andrew P. (Inventor); Goldfine, Neil J. (Inventor); Thomas, Zachary (Inventor); Jablonski, David A. (Inventor)

2015-01-01

Methods and apparatus for characterizing composite materials for manufacturing quality assurance (QA), periodic inspection during the useful life, or for forensic analysis/material testing. System are provided that relate eddy-current sensor responses to the fiber layup of a composite structure, the presence of impact damage on a composite structure with or without a metal liner, volumetric stress within the composite, fiber tow density, and other NDE inspection requirements. Also provided are systems that determine electromagnetic material properties and material dimensions of composite materials from capacitive sensor inspection measurements. These properties are related to the presence of buried defects in non-conductive composite materials, moisture ingress, aging of the material due to service or environmental/thermal exposure, or changes in manufacturing quality.

Tape-cast sensors and method of making

DOEpatents

Mukundan, Rangachary [Santa Fe, NM; Brosha, Eric L [Los Alamos, NM; Garzon, Fernando H [Santa Fe, NM

2009-08-18

A method of making electrochemical sensors in which an electrolyte material is cast into a tape. Prefabricated electrodes are then partially embedded between two wet layers of the electrolyte tape to form a green sensor, and the green sensor is then heated to sinter the electrolyte tape around the electrodes. The resulting sensors can be used in applications such as, but not limited to, combustion control, environmental monitoring, and explosive detection. A electrochemical sensor formed by the tape-casting method is also disclosed.

78 FR 41720 - CampCo Petition to Allow Commercial Distribution of Tritium Markers

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-11

...: Vanessa Cox, Office of Federal and State Materials and Environmental Management Programs, U.S. Nuclear...: The U.S. Nuclear Regulatory Commission (NRC) is publishing for comment a petition for rulemaking (PRM... 301-415-1677. Fax comments to: Secretary, U.S. Nuclear Regulatory Commission at 301-415-1101. Mail...

Recent Advances in the Fabrication and Application of Screen-Printed Electrochemical (Bio)Sensors Based on Carbon Materials for Biomedical, Agri-Food and Environmental Analyses

PubMed Central

Hughes, Gareth; Westmacott, Kelly; Honeychurch, Kevin C.; Crew, Adrian; Pemberton, Roy M.; Hart, John P.

2016-01-01

This review describes recent advances in the fabrication of electrochemical (bio)sensors based on screen-printing technology involving carbon materials and their application in biomedical, agri-food and environmental analyses. It will focus on the various strategies employed in the fabrication of screen-printed (bio)sensors, together with their performance characteristics; the application of these devices for the measurement of selected naturally occurring biomolecules, environmental pollutants and toxins will be discussed. PMID:27690118

Process and control systems for composites manufacturing

NASA Technical Reports Server (NTRS)

Tsiang, T. H.; Wanamaker, John L.

1992-01-01

A precise control of composite material processing would not only improve part quality, but it would also directly reduce the overall manufacturing cost. The development and incorporation of sensors will help to generate real-time information for material processing relationships and equipment characteristics. In the present work, the thermocouple, pressure transducer, and dielectrometer technologies were investigated. The monitoring sensors were integrated with the computerized control system in three non-autoclave fabrication techniques: hot-press, self contained tool (self heating and pressurizing), and pressure vessel). The sensors were implemented in the parts and tools.

Materials, methods and devices to detect and quantify water vapor concentrations in an atmosphere

DOEpatents

Allendorf, Mark D; Robinson, Alex L

2014-12-09

We have demonstrated that a surface acoustic wave (SAW) sensor coated with a nanoporous framework material (NFM) film can perform ultrasensitive water vapor detection at concentrations in air from 0.05 to 12,000 ppmv at 1 atmosphere pressure. The method is extendable to other MEMS-based sensors, such as microcantilevers, or to quartz crystal microbalance sensors. We identify a specific NFM that provides high sensitivity and selectivity to water vapor. However, our approach is generalizable to detection of other species using NFM to provide sensitivity and selectivity.

Performance of a Medipix3RX spectroscopic pixel detector with a high resistivity gallium arsenide sensor.

PubMed

Hamann, Elias; Koenig, Thomas; Zuber, Marcus; Cecilia, Angelica; Tyazhev, Anton; Tolbanov, Oleg; Procz, Simon; Fauler, Alex; Baumbach, Tilo; Fiederle, Michael

2015-03-01

High resistivity gallium arsenide is considered a suitable sensor material for spectroscopic X-ray imaging detectors. These sensors typically have thicknesses between a few hundred μm and 1 mm to ensure a high photon detection efficiency. However, for small pixel sizes down to several tens of μm, an effect called charge sharing reduces a detector's spectroscopic performance. The recently developed Medipix3RX readout chip overcomes this limitation by implementing a charge summing circuit, which allows the reconstruction of the full energy information of a photon interaction in a single pixel. In this work, we present the characterization of the first Medipix3RX detector assembly with a 500 μm thick high resistivity, chromium compensated gallium arsenide sensor. We analyze its properties and demonstrate the functionality of the charge summing mode by means of energy response functions recorded at a synchrotron. Furthermore, the imaging properties of the detector, in terms of its modulation transfer functions and signal-to-noise ratios, are investigated. After more than one decade of attempts to establish gallium arsenide as a sensor material for photon counting detectors, our results represent a breakthrough in obtaining detector-grade material. The sensor we introduce is therefore suitable for high resolution X-ray imaging applications.

A film-based wall shear stress sensor for wall-bounded turbulent flows

NASA Astrophysics Data System (ADS)

Amili, Omid; Soria, Julio

2011-07-01

In wall-bounded turbulent flows, determination of wall shear stress is an important task. The main objective of the present work is to develop a sensor which is capable of measuring surface shear stress over an extended region applicable to wall-bounded turbulent flows. This sensor, as a direct method for measuring wall shear stress, consists of mounting a thin flexible film on the solid surface. The sensor is made of a homogeneous, isotropic, and incompressible material. The geometry and mechanical properties of the film are measured, and particles with the nominal size of 11 μm in diameter are embedded on the film's surface to act as markers. An optical technique is used to measure the film deformation caused by the flow. The film has typically deflection of less than 2% of the material thickness under maximum loading. The sensor sensitivity can be adjusted by changing the thickness of the layer or the shear modulus of the film's material. The paper reports the sensor fabrication, static and dynamic calibration procedure, and its application to a fully developed turbulent channel flow at Reynolds numbers in the range of 90,000-130,000 based on the bulk velocity and channel full height. The results are compared to alternative wall shear stress measurement methods.

Increased in vivo stability and functional lifetime of an implantable glucose sensor through platinum catalysis.

PubMed

Colvin, Arthur E; Jiang, Hui

2013-05-01

Understanding and improving in vivo materials related to signal stability and preservation for active chemical sensor and biosensor transduction systems is critical in achieving implantable medical sensors for long-term in vivo applications. During human in vivo clinical testing of an implantable glucose sensor based on a glucose sensitive hydrogel, post-explant analysis showed that the boronate recognition element had been oxidized from the fluorescent indicator, causing a rapid loss of signal within hours after implant. Additional wet-bench analytical evidence and reproduction in vitro suggests reactive oxygen species, particularly hydrogen peroxide (H2O2), stemming from natural inflammatory response to the material, to be the cause of the observed oxidative de-boronation. A 3-nm thick deposition of metallic platinum (Pt) placed by plasma sputtering onto the porous surface of the hydrogel, showed immediate protection from sensor signal loss due to oxidation both in vitro and in vivo, greatly extending the useful lifetime of the implantable glucose sensor from 1 day to an expected ≥6 months. This finding may represent a new strategy to protect an implanted material and/or device from in vivo oxidative damage, leading to much improved overall stability and reliability for long-term applications. Copyright © 2012 Wiley Periodicals, Inc.

Chip-scale sensor system integration for portable health monitoring.

PubMed

Jokerst, Nan M; Brooke, Martin A; Cho, Sang-Yeon; Shang, Allan B

2007-12-01

The revolution in integrated circuits over the past 50 yr has produced inexpensive computing and communications systems that are powerful and portable. The technologies for these integrated chip-scale sensing systems, which will be miniature, lightweight, and portable, are emerging with the integration of sensors with electronics, optical systems, micromachines, microfluidics, and the integration of chemical and biological materials (soft/wet material integration with traditional dry/hard semiconductor materials). Hence, we stand at a threshold for health monitoring technology that promises to provide wearable biochemical sensing systems that are comfortable, inauspicious, wireless, and battery-operated, yet that continuously monitor health status, and can transmit compressed data signals at regular intervals, or alarm conditions immediately. In this paper, we explore recent results in chip-scale sensor integration technology for health monitoring. The development of inexpensive chip-scale biochemical optical sensors, such as microresonators, that are customizable for high sensitivity coupled with rapid prototyping will be discussed. Ground-breaking work in the integration of chip-scale optical systems to support these optical sensors will be highlighted, and the development of inexpensive Si complementary metal-oxide semiconductor circuitry (which makes up the vast majority of computational systems today) for signal processing and wireless communication with local receivers that lie directly on the chip-scale sensor head itself will be examined.

A teleoperated system for remote site characterization

NASA Technical Reports Server (NTRS)

Sandness, Gerald A.; Richardson, Bradley S.; Pence, Jon

1994-01-01

The detection and characterization of buried objects and materials is an important step in the restoration of burial sites containing chemical and radioactive waste materials at Department of Energy (DOE) and Department of Defense (DOD) facilities. By performing these tasks with remotely controlled sensors, it is possible to obtain improved data quality and consistency as well as enhanced safety for on-site workers. Therefore, the DOE Office of Technology Development and the US Army Environmental Center have jointly supported the development of the Remote Characterization System (RCS). One of the main components of the RCS is a small remotely driven survey vehicle that can transport various combinations of geophysical and radiological sensors. Currently implemented sensors include ground-penetrating radar, magnetometers, an electromagnetic induction sensor, and a sodium iodide radiation detector. The survey vehicle was constructed predominantly of non-metallic materials to minimize its effect on the operation of its geophysical sensors. The system operator controls the vehicle from a remote, truck-mounted, base station. Video images are transmitted to the base station by a radio link to give the operator necessary visual information. Vehicle control commands, tracking information, and sensor data are transmitted between the survey vehicle and the base station by means of a radio ethernet link. Precise vehicle tracking coordinates are provided by a differential Global Positioning System (GPS).

Ultra-wideband impedance sensor

DOEpatents

McEwan, Thomas E.

1999-01-01

The ultra-wideband impedance sensor (UWBZ sensor, or Z-sensor) is implemented in differential and single-ended configurations. The differential UWBZ sensor employs a sub-nanosecond impulse to determine the balance of an impedance bridge. The bridge is configured as a differential sample-and-hold circuit that has a reference impedance side and an unknown impedance side. The unknown impedance side includes a short transmission line whose impedance is a function of the near proximity of objects. The single-ended UWBZ sensor eliminates the reference side of the bridge and is formed of a sample and hold circuit having a transmission line whose impedance is a function of the near proximity of objects. The sensing range of the transmission line is bounded by the two-way travel time of the impulse, thereby eliminating spurious Doppler modes from large distant objects that would occur in a microwave CW impedance bridge. Thus, the UWBZ sensor is a range-gated proximity sensor. The Z-sensor senses the near proximity of various materials such as metal, plastic, wood, petroleum products, and living tissue. It is much like a capacitance sensor, yet it is impervious to moisture. One broad application area is the general replacement of magnetic sensors, particularly where nonferrous materials need to be sensed. Another broad application area is sensing full/empty levels in tanks, vats and silos, e.g., a full/empty switch in water or petroleum tanks.

Ultra-wideband impedance sensor

DOEpatents

McEwan, T.E.

1999-03-16

The ultra-wideband impedance sensor (UWBZ sensor, or Z-sensor) is implemented in differential and single-ended configurations. The differential UWBZ sensor employs a sub-nanosecond impulse to determine the balance of an impedance bridge. The bridge is configured as a differential sample-and-hold circuit that has a reference impedance side and an unknown impedance side. The unknown impedance side includes a short transmission line whose impedance is a function of the near proximity of objects. The single-ended UWBZ sensor eliminates the reference side of the bridge and is formed of a sample and hold circuit having a transmission line whose impedance is a function of the near proximity of objects. The sensing range of the transmission line is bounded by the two-way travel time of the impulse, thereby eliminating spurious Doppler modes from large distant objects that would occur in a microwave CW impedance bridge. Thus, the UWBZ sensor is a range-gated proximity sensor. The Z-sensor senses the near proximity of various materials such as metal, plastic, wood, petroleum products, and living tissue. It is much like a capacitance sensor, yet it is impervious to moisture. One broad application area is the general replacement of magnetic sensors, particularly where nonferrous materials need to be sensed. Another broad application area is sensing full/empty levels in tanks, vats and silos, e.g., a full/empty switch in water or petroleum tanks. 2 figs.

Evaluation of the biocompatibility of a coating material for an implantable bladder volume sensor.

PubMed

Kim, Su-Jin; Lee, Dong-Sup; Kim, In-Gul; Sohn, Dong-Wan; Park, Jung-Yul; Choi, Bum-Kyoo; Kim, Sae-Woong

2012-03-01

As the applications for implantable medical devices have increased, the need for biocompatible packaging materials has become important. Recently, we reported an implantable sensor for real-time monitoring of the changes in bladder volume, which necessitated finding a safe coating material for use in bladder tissue. At present, materials like polyethylene glycol (PEG), polydimethylsiloxane (PDMS) and parylene-C are used in biomedical devices or as coating materials, owing to their excellent safety in various medical fields. However, few studies have assessed their safety in bladder tissue, therefore, we evaluated the biocompatibility of PEG, PDMS and parylene-C in the bladder. All three materials turned out to be safe in in vitro tests of live/dead staining and cell viability. In vivo tests with hematoxylin and eosin and immunofluorescence staining with MAC387 showed no persistent inflammation. Therefore, we consider that the three materials are biocompatible in bladder tissue. Despite this safety, however, PEG has biodegradable characteristics and thus is not suitable for use as packaging. We suggest that PDMS and parylene-C can be used as safe coating materials for the implantable bladder volume sensor reported previously. Copyright © 2012. Published by Elsevier B.V.

The mid-IR silicon photonics sensor platform (Conference Presentation)

NASA Astrophysics Data System (ADS)

Kimerling, Lionel; Hu, Juejun; Agarwal, Anuradha M.

2017-02-01

Advances in integrated silicon photonics are enabling highly connected sensor networks that offer sensitivity, selectivity and pattern recognition. Cost, performance and the evolution path of the so-called `Internet of Things' will gate the proliferation of these networks. The wavelength spectral range of 3-8um, commonly known as the mid-IR, is critical to specificity for sensors that identify materials by detection of local vibrational modes, reflectivity and thermal emission. For ubiquitous sensing applications in this regime, the sensors must move from premium to commodity level manufacturing volumes and cost. Scaling performance/cost is critically dependent on establishing a minimum set of platform attributes for point, wearable, and physical sensing. Optical sensors are ideal for non-invasive applications. Optical sensor device physics involves evanescent or intra-cavity structures for applied to concentration, interrogation and photo-catalysis functions. The ultimate utility of a platform is dependent on sample delivery/presentation modalities; system reset, recalibration and maintenance capabilities; and sensitivity and selectivity performance. The attributes and performance of a unified Glass-on-Silicon platform has shown good prospects for heterogeneous integration on materials and devices using a low cost process flow. Integrated, single mode, silicon photonic platforms offer significant performance and cost advantages, but they require discovery and qualification of new materials and process integration schemes for the mid-IR. Waveguide integrated light sources based on rare earth dopants and Ge-pumped frequency combs have promise. Optical resonators and waveguide spirals can enhance sensitivity. PbTe materials are among the best choices for a standard, waveguide integrated photodetector. Chalcogenide glasses are capable of transmitting mid-IR signals with high transparency. Integrated sensor case studies of i) high sensitivity analyte detection in solution; ii) gas sensing in air and iii) on-chip spectrometry provide good insight into the tradeoffs being made en route to ubiquitous sensor deployment in an Internet of Things.

Investigating nanohybrid material based on 3D CNTs@Cu nanoparticle composite and imprinted polymer for highly selective detection of chloramphenicol.

PubMed

Munawar, Anam; Tahir, Muhammad Ali; Shaheen, Ayesha; Lieberzeit, Peter A; Khan, Waheed S; Bajwa, Sadia Z

2018-01-15

Nanotechnology holds great promise for the fabrication of versatile materials that can be used as sensor platforms for the highly selective detection of analytes. In this research article we report a new nanohybrid material, where 3D imprinted nanostructures are constructed. First, copper nanoparticles are deposited on carbon nanotubes and then a hybrid structure is formed by coating molecularly imprinted polymer on 3D CNTs@Cu NPs; and a layer by layer assembly is achieved. SEM and AFM revealed the presence of Cu NPs (100-500nm) anchored along the whole length of CNTs, topped with imprinted layer. This material was applied to fabricate an electrochemical sensor to monitor a model veterinary drug, chloramphenicol. The high electron transfer ability and conductivity of the prepared material produced sensitive response, whereas, molecular imprinting produces selectivity towards drug detection. The sensor responses were found concentration dependent and the detection limit was calculated to be 10μM (S/N=3). Finally, we showed how changing the polymer composition, the extent of cross linking, and sensor layer thickness greatly affects the number of binding sites for the recognition of drug. This work paves the way to build variants of 3D imprinted materials for the detection of other kinds of biomolecules and antibiotics. Copyright © 2017 Elsevier B.V. All rights reserved.

Nanostructured Bulk Thermoelectric Generator for Efficient Power Harvesting for Self-powered Sensor Networks

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

Zhang, Yanliang; Butt, Darryl; Agarwal, Vivek

2015-07-01

The objective of this Nuclear Energy Enabling Technology research project is to develop high-efficiency and reliable thermoelectric generators for self-powered wireless sensors nodes utilizing thermal energy from nuclear plant or fuel cycle. The power harvesting technology has crosscutting significance to address critical technology gaps in monitoring nuclear plants and fuel cycle. The outcomes of the project will lead to significant advancement in sensors and instrumentation technology, reducing cost, improving monitoring reliability and therefore enhancing safety. The self-powered wireless sensor networks could support the long-term safe and economical operation of all the reactor designs and fuel cycle concepts, as well asmore » spent fuel storage and many other nuclear science and engineering applications. The research is based on recent breakthroughs in high-performance nanostructured bulk (nanobulk) thermoelectric materials that enable high-efficiency direct heat-to-electricity conversion over a wide temperature range. The nanobulk thermoelectric materials that the research team at Boise State University and University of Houston has developed yield up to a 50% increase in the thermoelectric figure of merit, ZT, compared with state-of-the-art bulk counterparts. This report focuses on the selection of optimal thermoelectric materials for this project. The team has performed extensive study on two thermoelectric materials systems, i.e. the half-Heusler materials, and the Bismuth-Telluride materials. The report contains our recent research results on the fabrication, characterization and thermoelectric property measurements of these two materials.« less

Intelligent Multi-scale Sensors for Damage Identification and Mitigation in Woven Composites for Aerospace Structural Applications

DTIC Science & Technology

2012-08-15

Bragg grating ( FBG ) sensors within these composite structures allows one to correlate sensor response features to “critical damage events” within the...material. The unique capabilities of this identification strategy are due to the detailed information obtained from the FBG sensors and the... FBG sensors relate to damage states not merely strain amplitudes. The research objectives of this project were therefore to:  demonstrate FBG

Nondestructive testing of advanced materials using sensors with metamaterials

NASA Astrophysics Data System (ADS)

Rozina, Steigmann; Narcis Andrei, Danila; Nicoleta, Iftimie; Catalin-Andrei, Tugui; Frantisek, Novy; Stanislava, Fintova; Petrica, Vizureanu; Adriana, Savin

2016-11-01

This work presents a method for nondestructive evaluation (NDE) of advanced materials that makes use of the images in near field and the concentration of flux using the phenomenon of spatial resolution. The method allows the detection of flaws as crack, nonadhesion of coating, degradation or presence delamination stresses correlated with the response of electromagnetic sensor.

Practical applications of nondestructive materials characterization

NASA Astrophysics Data System (ADS)

Green, Robert E., Jr.

1992-10-01

Nondestructive evaluation (NDE) techniques are reviewed for applications to the industrial production of materials including microstructural, physical, and chemical analyses. NDE techniques addressed include: (1) double-pulse holographic interferometry for sealed-package leak testing; (2) process controls for noncontact metals fabrication; (3) ultrasonic detections of oxygen contamination in titanium welds; and (4) scanning acoustic microscopy for the evaluation of solder bonds. The use of embedded sensors and emerging NDE concepts provides the means for controlling the manufacturing and quality of quartz crystal resonators, nickel single-crystal turbine blades, and integrated circuits. Advances in sensor technology and artificial intelligence algorithms and the use of embedded sensors combine to make NDE technology highly effective in controlling industrial materials manufacturing and the quality of the products.

Electro-chemical sensors, sensor arrays and circuits

DOEpatents

Katz, Howard E.; Kong, Hoyoul

2014-07-08

An electro-chemical sensor includes a first electrode, a second electrode spaced apart from the first electrode, and a semiconductor channel in electrical contact with the first and second electrodes. The semiconductor channel includes a trapping material. The trapping material reduces an ability of the semiconductor channel to conduct a current of charge carriers by trapping at least some of the charge carriers to localized regions within the semiconductor channel. The semiconductor channel includes at least a portion configured to be exposed to an analyte to be detected, and the trapping material, when exposed to the analyte, interacts with the analyte so as to at least partially restore the ability of the semiconductor channel to conduct the current of charge carriers.

Optical Fiber Chemical Sensor with Sol-Gel Derived Refractive Material as Transducer for High Temperature Gas Sensing in Clean Coal Technology

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

Shiquan Tao

2006-12-31

The chemistry of sol-gel derived silica and refractive metal oxide has been systematically studied. Sol-gel processes have been developed for preparing porous silica and semiconductor metal oxide materials. Micelle/reversed micelle techniques have been developed for preparing nanometer sized semiconductor metal oxides and noble metal particles. Techniques for doping metal ions, metal oxides and nanosized metal particles into porous sol-gel material have also been developed. Optical properties of sol-gel derived materials in ambient and high temperature gases have been studied by using fiber optic spectroscopic techniques, such as fiber optic ultraviolet/visible absorption spectrometry, fiber optic near infrared absorption spectrometry and fibermore » optic fluorescence spectrometry. Fiber optic spectrometric techniques have been developed for investigating the optical properties of these sol-gel derived materials prepared as porous optical fibers or as coatings on the surface of silica optical fibers. Optical and electron microscopic techniques have been used to observe the microstructure, such as pore size, pore shape, sensing agent distribution, of sol-gel derived material, as well as the size and morphology of nanometer metal particle doped in sol-gel derived porous silica, the nature of coating of sol-gel derived materials on silica optical fiber surface. In addition, the chemical reactions of metal ion, nanostructured semiconductor metal oxides and nanometer sized metal particles with gas components at room temperature and high temperatures have also been investigated with fiber optic spectrometric methods. Three classes of fiber optic sensors have been developed based on the thorough investigation of sol-gel chemistry and sol-gel derived materials. The first group of fiber optic sensors uses porous silica optical fibers doped with metal ions or metal oxide as transducers for sensing trace NH{sub 3} and H{sub 2}S in high temperature gas samples. The second group of fiber optic sensors uses sol-gel derived porous silica materials doped with nanometer particles of noble metals in the form of fiber or coating for sensing trace H{sub 2}, NH{sub 3} and HCl in gas samples at for applications ambient temperature. The third classes of fiber optic sensors use sol-gel derived semiconductor metal oxide coating on the surface of silica optical fiber as transducers for selectively sensing H{sub 2}, CH{sub 4} and CO at high temperature. In addition, optical fiber temperature sensors use the fluorescence signal of rare-earth metal ions doped porous silica optical fiber or the optical absorption signal of thermochromic metal oxide materials coated on the surface of silica optical fibers have also been developed for monitoring gas temperature of corrosive gas. Based on the results obtained from this project, the principle of fiber optic sensor techniques for monitoring matrix gas components as well as trace components of coal gasification derived syngas has been established. Prototype sensors for sensing trace ammonia and hydrogen sulfide in gasification derived syngas have been built up in our laboratory and have been tested using gas samples with matrix gas composition similar to that of gasification derived fuel gas. Test results illustrated the feasibility of these sensors for applications in IGCC processes.« less

Flexible strain sensor based on carbon nanotube rubber composites

NASA Astrophysics Data System (ADS)

Kim, Jin-Ho; Kim, Young-Ju; Baek, Woon Kyung; Lim, Kwon Taek; Kang, Inpil

2010-04-01

Electrically conducting rubber composites (CRC) with carbon nanotubes (CNTs) filler have received much attention as potential materials for sensors. In this work, Ethylene propylene diene M-class rubber (EPDM)/CNT composites as a novel nano sensory material were prepared to develop flexible strain sensors that can measure large deformation of flexible structures. The EPDM/CNT composites were prepared by using a Brabender mixer with multi-walled CNTs and organo-clay. A strain sensor made of EPDM/CNT composite was attached to the surface of a flexible beam and change of resistance of the strain sensor was measured with respect to the beam deflection. Resistance of the sensor was change quite linearly under the bending and compressive large beam deflection. Upon external forces, CRC deformation takes place with the micro scale change of inter-electrical condition in rubber matrix due to the change of contact resistance, and CRC reveals macro scale piezoresistivity. It is anticipated that the CNT/EPDM fibrous strain sensor can be eligible to develop a biomimetic artificial neuron that can continuously sense deformation, pressure and shear force.

Odorant binding protein based biomimetic sensors for detection of alcohols associated with Salmonella contamination in packaged beef.

PubMed

Sankaran, Sindhuja; Panigrahi, Suranjan; Mallik, Sanku

2011-03-15

Detection of food-borne bacteria present in the food products is critical to prevent the spread of infectious diseases. Intelligent quality sensors are being developed for detecting bacterial pathogens such as Salmonella in beef. One of our research thrusts was to develop novel sensing materials sensitive to specific indicator alcohols at low concentrations. Present work focuses on developing olfactory sensors mimicking insect odorant binding protein to detect alcohols in low concentrations at room temperature. A quartz crystal microbalance (QCM) based sensor in conjunction with synthetic peptide was developed to detect volatile organic compounds indicative to Salmonella contamination in packaged beef. The peptide sequence used as sensing materials was derived from the amino acids sequence of Drosophila odorant binding protein, LUSH. The sensors were used to detect alcohols: 3-methyl-1-butanol and 1-hexanol. The sensors were sensitive to alcohols with estimated lower detection limits of <5 ppm. Thus, the LUSH-derived QCM sensors exhibited potential to detect alcohols at low ppm concentrations. Copyright © 2011. Published by Elsevier B.V.

A diagnostic for quantifying heat flux from a thermite spray

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

E. P. Nixon; M. L. Pantoya; D. J. Prentice

2010-02-01

Characterizing the combustion behaviors of energetic materials requires diagnostic tools that are often not readily or commercially available. For example, a jet of thermite spray provides a high temperature and pressure reaction that can also be highly corrosive and promote undesirable conditions for the survivability of any sensor. Developing a diagnostic to quantify heat flux from a thermite spray is the objective of this study. Quick response sensors such as thin film heat flux sensors cannot survive the harsh conditions of the spray, but more rugged sensors lack the response time for the resolution desired. A sensor that will allowmore » for adequate response time while surviving the entire test duration was constructed. The sensor outputs interior temperatures of the probes at known locations and utilizes an inverse heat conduction code to calculate heat flux values. The details of this device are discussed and illustrated. Temperature and heat flux measurements of various thermite sprays are reported. Results indicate that this newly designed heat flux sensor provides quantitative data with good repeatability suitable for characterizing energetic material combustion.« less

QUANTIFICATION OF HEAT FLUX FROM A REACTING THERMITE SPRAY

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

Eric Nixon; Michelle Pantoya

2009-07-01

Characterizing the combustion behaviors of energetic materials requires diagnostic tools that are often not readily or commercially available. For example, a jet of thermite spray provides a high temperature and pressure reaction that can also be highly corrosive and promote undesirable conditions for the survivability of any sensor. Developing a diagnostic to quantify heat flux from a thermite spray is the objective of this study. Quick response sensors such as thin film heat flux sensors can not survive the harsh conditions of the spray, but more rugged sensors lack the response time for the resolution desired. A sensor that willmore » allow for adequate response time while surviving the entire test duration was constructed. The sensor outputs interior temperatures of the probes at known locations and utilizes an inverse heat conduction code to calculate heat flux values. The details of this device are discussed and illustrated. Temperature and heat flux measurements of various thermite spray conditions are reported. Results indicate that this newly developed energetic material heat flux sensor provides quantitative data with good repeatability.« less

Thin Film Sensors for Surface Measurements

NASA Technical Reports Server (NTRS)

Martin, Lisa C.; Wrbanek, John D.; Fralick, Gustave C.

2001-01-01

Advanced thin film sensors that can provide accurate surface temperature, strain, and heat flux measurements have been developed at NASA Glenn Research Center. These sensors provide minimally intrusive characterization of advanced propulsion materials and components in hostile, high-temperature environments as well as validation of propulsion system design codes. The sensors are designed for applications on different material systems and engine components for testing in engine simulation facilities. Thin film thermocouples and strain gauges for the measurement of surface temperature and strain have been demonstrated on metals, ceramics and advanced ceramic-based composites of various component configurations. Test environments have included both air-breathing and space propulsion-based engine and burner rig environments at surface temperatures up to 1100 C and under high gas flow and pressure conditions. The technologies developed for these sensors as well as for a thin film heat flux gauge have been integrated into a single multifunctional gauge for the simultaneous real-time measurement of surface temperature, strain, and heat flux. This is the first step toward the development of smart sensors with integrated signal conditioning and high temperature electronics that would have the capability to provide feedback to the operating system in real-time. A description of the fabrication process for the thin film sensors and multifunctional gauge will be provided. In addition, the material systems on which the sensors have been demonstrated, the test facilities and the results of the tests to-date will be described. Finally, the results will be provided of the current effort to demonstrate the capabilities of the multifunctional gauge.

Porous silver nanosheets: a novel sensing material for nanoscale and microscale airflow sensors

NASA Astrophysics Data System (ADS)

Marzbanrad, Ehsan; Zhao, Boxin; Zhou, Norman Y.

2015-11-01

Fabrication of nanoscale and microscale machines and devices is one of the goals of nanotechnology. For this purpose, different materials, methods, and devices should be developed. Among them, various types of miniaturized sensors are required to build the nanoscale and microscale systems. In this research, we introduce a new nanoscale sensing material, silver nanosheets, for applications such as nanoscale and microscale gas flow sensors. The silver nanosheets were synthesized through the reduction of silver ions by ascorbic acid in the presence of poly(methacrylic acid) as a capping agent, followed by the growth of silver in the shape of hexagonal and triangular nanoplates, and self-assembly and nanojoining of these structural blocks. At the end of this process, the synthesized nanosheets were floated on the solution. Then, their electrical and thermal stability was demonstrated at 120 °C, and their atmospheric corrosion resistance was clarified at the same temperature range by thermogravimetric analysis. We employed the silver nanosheets in fabricating airflow sensors by scooping out the nanosheets by means of a sensor substrate, drying them at room temperature, and then annealing them at 300 °C for one hour. The fabricated sensors were tested for their ability to measure airflow in the range of 1 to 5 ml min-1, which resulted in a linear response to the airflow with a response and recovery time around 2 s. Moreover, continuous dynamic testing demonstrated that the response of the sensors was stable and hence the sensors can be used for a long time without detectable drift in their response.

Data Fusion for a Vision-Radiological System for Source Tracking and Discovery

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

Enqvist, Andreas; Koppal, Sanjeev

2015-07-01

A multidisciplinary approach to allow the tracking of the movement of radioactive sources by fusing data from multiple radiological and visual sensors is under development. The goal is to improve the ability to detect, locate, track and identify nuclear/radiological threats. The key concept is that such widely available visual and depth sensors can impact radiological detection, since the intensity fall-off in the count rate can be correlated to movement in three dimensions. To enable this, we pose an important question; what is the right combination of sensing modalities and vision algorithms that can best compliment a radiological sensor, for themore » purpose of detection and tracking of radioactive material? Similarly what is the best radiation detection methods and unfolding algorithms suited for data fusion with tracking data? Data fusion of multi-sensor data for radiation detection have seen some interesting developments lately. Significant examples include intelligent radiation sensor systems (IRSS), which are based on larger numbers of distributed similar or identical radiation sensors coupled with position data for network capable to detect and locate radiation source. Other developments are gamma-ray imaging systems based on Compton scatter in segmented detector arrays. Similar developments using coded apertures or scatter cameras for neutrons have recently occurred. The main limitation of such systems is not so much in their capability but rather in their complexity and cost which is prohibitive for large scale deployment. Presented here is a fusion system based on simple, low-cost computer vision and radiological sensors for tracking of multiple objects and identifying potential radiological materials being transported or shipped. The main focus of this work is the development on two separate calibration algorithms for characterizing the fused sensor system. The deviation from a simple inverse square-root fall-off of radiation intensity is explored and accounted for. In particular, the computer vision system enables a map of distance-dependence of the sources being tracked. Infrared, laser or stereoscopic vision sensors are all options for computer-vision implementation depending on interior vs exterior deployment, resolution desired and other factors. Similarly the radiation sensors will be focused on gamma-ray or neutron detection due to the long travel length and ability to penetrate even moderate shielding. There is a significant difference between the vision sensors and radiation sensors in the way the 'source' or signals are generated. A vision sensor needs an external light-source to illuminate the object and then detects the re-emitted illumination (or lack thereof). However, for a radiation detector, the radioactive material is the source itself. The only exception to this is the field of active interrogations where radiation is beamed into a material to entice new/additional radiation emission beyond what the material would emit spontaneously. The aspect of the nuclear material being the source itself means that all other objects in the environment are 'illuminated' or irradiated by the source. Most radiation will readily penetrate regular material, scatter in new directions or be absorbed. Thus if a radiation source is located near a larger object that object will in turn scatter some radiation that was initially emitted in a direction other than the direction of the radiation detector, this can add to the count rate that is observed. The effect of these scatter is a deviation from the traditional distance dependence of the radiation signal and is a key challenge that needs a combined system calibration solution and algorithms. Thus both an algebraic approach as well as a statistical approach have been developed and independently evaluated to investigate the sensitivity to this deviation from the simplified radiation fall-off as a function of distance. The resulting calibrated system algorithms are used and demonstrated in various laboratory scenarios, and later in realistic tracking scenarios. The selection and testing of radiological and computer-vision sensors for the additional specific scenarios will be the subject of ongoing and future work. (authors)« less

Review on State-of-the-art in Polymer Based pH Sensors

PubMed Central

Korostynska, Olga; Arshak, Khalil; Gill, Edric; Arshak, Arousian

2007-01-01

This paper reviews current state-of-the-art methods of measuring pH levels that are based on polymer materials. These include polymer-coated fibre optic sensors, devices with electrodes modified with pH-sensitive polymers, fluorescent pH indicators, potentiometric pH sensors as well as sensors that use combinatory approach for ion concentration monitoring. PMID:28903277

Measuring Thicknesses of Wastewater Films

NASA Technical Reports Server (NTRS)

Schubert, F. H.; Davenport, R. J.

1987-01-01

Sensor determines when thickness of film of electrically conductive wastewater on rotating evaporator drum exceeds preset value. Sensor simple electrical probe that makes contact with liquid surface. Made of materials resistant to chemicals in liquid. Mounted on shaft in rotating cylinder, liquid-thickness sensor extends toward cylinder wall so tip almost touches. Sensor body accommodates probe measuring temperature of evaporated water in cylinder.

Geomembrane barriers using integral fiber optics to monitor barrier integrity

DOEpatents

Staller, G.E.; Wemple, R.P.

1996-10-22

This invention provides a geomembrane or geotextile with embedded optical sensors that are used to monitor the status of containment site barriers. Fiber optic strands are used to form the sensors that can detect and monitor conditions at the sites such as breaches, slope creep, subsidence, leachate levels, fires, and types of materials present or leaking from the site. The strands are integral to the membrane or textile materials. The geosynthetic membrane is deployed at the site in a fashion similar to carpet laying. Edges of the membrane or textile are joined to form a liner and the ends of the membrane or textile become the connection zones for obtaining signals from the sensors. A connection interface with a control system to generate Optical Time Delay Response or other light signals for transmission to the optic fiber strands or sensors and also to receive reflected signals from the sensors is included in the system. Software to interpret the sensor signals can be used in the geosynthetic monitoring system. 6 figs.

Geomembrane barriers using integral fiber optics to monitor barrier integrity

DOEpatents

Staller, George E.; Wemple, Robert P.

1996-01-01

This invention provides a geomembrane or geotextile with embedded optical sensors that are used to monitor the status of containment site barriers. Fiber optic strands are used to form the sensors that can detect and monitor conditions at the sites such as breaches, slope creep, subsidence, leachate levels, fires, and types of materials present or leaking from the site. The strands are integral to the membrane or textile materials. The geosythetic membrane is deployed at the site in a fashion similar to carpet laying. Edges of the membrane or textile are joined to form a liner and the ends of the membrane or textile become the connection zones for obtaining signals from the sensors. A connection interface with a control system to generate Optical Time Delay Response or other light signals for transmission to the optic fiber strands or sensors and also to receive reflected signals from the sensors is included in the system. Software to interpret the sensor signals can be used in the geosythetic monitoring system.

Electrochemical DNA Hybridization Sensors Based on Conducting Polymers

PubMed Central

Rahman, Md. Mahbubur; Li, Xiao-Bo; Lopa, Nasrin Siraj; Ahn, Sang Jung; Lee, Jae-Joon

2015-01-01

Conducting polymers (CPs) are a group of polymeric materials that have attracted considerable attention because of their unique electronic, chemical, and biochemical properties. This is reflected in their use in a wide range of potential applications, including light-emitting diodes, anti-static coating, electrochromic materials, solar cells, chemical sensors, biosensors, and drug-release systems. Electrochemical DNA sensors based on CPs can be used in numerous areas related to human health. This review summarizes the recent progress made in the development and use of CP-based electrochemical DNA hybridization sensors. We discuss the distinct properties of CPs with respect to their use in the immobilization of probe DNA on electrode surfaces, and we describe the immobilization techniques used for developing DNA hybridization sensors together with the various transduction methods employed. In the concluding part of this review, we present some of the challenges faced in the use of CP-based DNA hybridization sensors, as well as a future perspective. PMID:25664436

A Rapid Process for Fabricating Gas Sensors

PubMed Central

Hsiao, Chun-Ching; Luo, Li-Siang

2014-01-01

Zinc oxide (ZnO) is a low-toxicity and environmentally-friendly material applied on devices, sensors or actuators for “green” usage. A porous ZnO film deposited by a rapid process of aerosol deposition (AD) was employed as the gas-sensitive material in a CO gas sensor to reduce both manufacturing cost and time, and to further extend the AD application for a large-scale production. The relative resistance change (ΔR/R) of the ZnO gas sensor was used for gas measurement. The fabricated ZnO gas sensors were measured with operating temperatures ranging from 110 °C to 180 °C, and CO concentrations ranging from 100 ppm to 1000 ppm. The sensitivity and the response time presented good performance at increasing operating temperatures and CO concentrations. AD was successfully for applied for making ZnO gas sensors with great potential for achieving high deposition rates at low deposition temperatures, large-scale production and low cost. PMID:25010696

Wireless sensors and sensor networks for homeland security applications.

PubMed

Potyrailo, Radislav A; Nagraj, Nandini; Surman, Cheryl; Boudries, Hacene; Lai, Hanh; Slocik, Joseph M; Kelley-Loughnane, Nancy; Naik, Rajesh R

2012-11-01

New sensor technologies for homeland security applications must meet the key requirements of sensitivity to detect agents below risk levels, selectivity to provide minimal false-alarm rates, and response speed to operate in high throughput environments, such as airports, sea ports, and other public places. Chemical detection using existing sensor systems is facing a major challenge of selectivity. In this review, we provide a brief summary of chemical threats of homeland security importance; focus in detail on modern concepts in chemical sensing; examine the origins of the most significant unmet needs in existing chemical sensors; and, analyze opportunities, specific requirements, and challenges for wireless chemical sensors and wireless sensor networks (WSNs). We further review a new approach for selective chemical sensing that involves the combination of a sensing material that has different response mechanisms to different species of interest, with a transducer that has a multi-variable signal-transduction ability. This new selective chemical-sensing approach was realized using an attractive ubiquitous platform of battery-free passive radio-frequency identification (RFID) tags adapted for chemical sensing. We illustrate the performance of RFID sensors developed in measurements of toxic industrial materials, humidity-independent detection of toxic vapors, and detection of chemical-agent simulants, explosives, and strong oxidizers.

Methodology for the design, production, and test of plastic optical displacement sensors

NASA Astrophysics Data System (ADS)

Rahlves, Maik; Kelb, Christian; Reithmeier, Eduard; Roth, Bernhard

2016-08-01

Optical displacement sensors made entirely from plastic materials offer various advantages such as biocompatibility and high flexibility compared to their commonly used electrical and glass-based counterparts. In addition, various low-cost and large-scale fabrication techniques can potentially be utilized for their fabrication. In this work we present a toolkit for the design, production, and test of such sensors. Using the introduced methods, we demonstrate the development of a simple all-optical displacement sensor based on multimode plastic waveguides. The system consists of polymethylmethacrylate and cyclic olefin polymer which serve as cladding and core materials, respectively. We discuss several numerical models which are useful for the design and simulation of the displacement sensors as well as two manufacturing methods capable of mass-producing such devices. Prior to fabrication, the sensor layout and performance are evaluated by means of a self-implemented ray-optical simulation which can be extended to various other types of sensor concepts. Furthermore, we discuss optical and mechanical test procedures as well as a high-precision tensile testing machine especially suited for the characterization of the opto-mechanical performance of such plastic optical displacement sensors.

Efficient Skin Temperature Sensor and Stable Gel-Less Sticky ECG Sensor for a Wearable Flexible Healthcare Patch.

PubMed

Yamamoto, Yuki; Yamamoto, Daisuke; Takada, Makoto; Naito, Hiroyoshi; Arie, Takayuki; Akita, Seiji; Takei, Kuniharu

2017-09-01

Wearable, flexible healthcare devices, which can monitor health data to predict and diagnose disease in advance, benefit society. Toward this future, various flexible and stretchable sensors as well as other components are demonstrated by arranging materials, structures, and processes. Although there are many sensor demonstrations, the fundamental characteristics such as the dependence of a temperature sensor on film thickness and the impact of adhesive for an electrocardiogram (ECG) sensor are yet to be explored in detail. In this study, the effect of film thickness for skin temperature measurements, adhesive force, and reliability of gel-less ECG sensors as well as an integrated real-time demonstration is reported. Depending on the ambient conditions, film thickness strongly affects the precision of skin temperature measurements, resulting in a thin flexible film suitable for a temperature sensor in wearable device applications. Furthermore, by arranging the material composition, stable gel-less sticky ECG electrodes are realized. Finally, real-time simultaneous skin temperature and ECG signal recordings are demonstrated by attaching an optimized device onto a volunteer's chest. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Humidity Sensors Principle, Mechanism, and Fabrication Technologies: A Comprehensive Review

PubMed Central

Farahani, Hamid; Wagiran, Rahman; Hamidon, Mohd Nizar

2014-01-01

Humidity measurement is one of the most significant issues in various areas of applications such as instrumentation, automated systems, agriculture, climatology and GIS. Numerous sorts of humidity sensors fabricated and developed for industrial and laboratory applications are reviewed and presented in this article. The survey frequently concentrates on the RH sensors based upon their organic and inorganic functional materials, e.g., porous ceramics (semiconductors), polymers, ceramic/polymer and electrolytes, as well as conduction mechanism and fabrication technologies. A significant aim of this review is to provide a distinct categorization pursuant to state of the art humidity sensor types, principles of work, sensing substances, transduction mechanisms, and production technologies. Furthermore, performance characteristics of the different humidity sensors such as electrical and statistical data will be detailed and gives an added value to the report. By comparison of overall prospects of the sensors it was revealed that there are still drawbacks as to efficiency of sensing elements and conduction values. The flexibility offered by thick film and thin film processes either in the preparation of materials or in the choice of shape and size of the sensor structure provides advantages over other technologies. These ceramic sensors show faster response than other types. PMID:24784036

Metal-Organic Frameworks-Derived Hierarchical Co3O4 Structures as Efficient Sensing Materials for Acetone Detection.

PubMed

Zhang, Rui; Zhou, Tingting; Wang, Lili; Zhang, Tong

2018-03-21

Highly sensitive and stable gas sensors have attracted much attention because they are the key to innovations in the fields of environment, health, energy savings and security, etc. Sensing materials, which influence the practical sensing performance, are the crucial parts for gas sensors. Metal-organic frameworks (MOFs) are considered as alluring sensing materials for gas sensors because of the possession of high specific surface area, unique morphology, abundant metal sites, and functional linkers. Herein, four kinds of porous hierarchical Co 3 O 4 structures have been selectively controlled by optimizing the thermal decomposition (temperature, rate, and atmosphere) using ZIF-67 as precursor that was obtained from coprecipitation method with the co-assistance of cobalt salt and 2-methylimidazole in the solution of methanol. These hierarchical Co 3 O 4 structures, with controllable cross-linked channels, meso-/micropores, and adjustable surface area, are efficient catalytic materials for gas sensing. Benefits from structural advantages, core-shell, and porous core-shell Co 3 O 4 exhibit enhanced sensing performance compared to those of porous popcorn and nanoparticle Co 3 O 4 to acetone gas. These novel MOF-templated Co 3 O 4 hierarchical structures are so fantastic that they can be expected to be efficient sensing materials for development of low-temperature operating gas sensors.

Efficient Flame Detection and Early Warning Sensors on Combustible Materials Using Hierarchical Graphene Oxide/Silicone Coatings.

PubMed

Wu, Qian; Gong, Li-Xiu; Li, Yang; Cao, Cheng-Fei; Tang, Long-Cheng; Wu, Lianbin; Zhao, Li; Zhang, Guo-Dong; Li, Shi-Neng; Gao, Jiefeng; Li, Yongjin; Mai, Yiu-Wing

2018-01-23

Design and development of smart sensors for rapid flame detection in postcombustion and early fire warning in precombustion situations are critically needed to improve the fire safety of combustible materials in many applications. Herein, we describe the fabrication of hierarchical coatings created by assembling a multilayered graphene oxide (GO)/silicone structure onto different combustible substrate materials. The resulting coatings exhibit distinct temperature-responsive electrical resistance change as efficient early warning sensors for detecting abnormal high environmental temperature, thus enabling fire prevention below the ignition temperature of combustible materials. After encountering a flame attack, we demonstrate extremely rapid flame detection response in 2-3 s and excellent flame self-extinguishing retardancy for the multilayered GO/silicone structure that can be synergistically transformed to a multiscale graphene/nanosilica protection layer. The hierarchical coatings developed are promising for fire prevention and protection applications in various critical fire risk and related perilous circumstances.

Lactoferrin from Camelus dromedarius Inhibits Nuclear Transcription Factor-kappa B Activation, Cyclooxygenase-2 Expression and Prostaglandin E2 Production in Stimulated Human Chondrocytes

PubMed Central

Rasheed, Naila; Alghasham, Abdullah; Rasheed, Zafar

2016-01-01

Background: Osteoarthritis (OA) is a progressive joint disorder, which remains the leading cause of chronic disability in aged people. Nuclear factor-kappa B (NF)-κB is a major cellular event in OA and its activation by interleukin-1β (IL-1β) plays a critical role in cartilage breakdown in these patients. Objective: In this study, we examined the effect of lactoferrin on NF-κB activation, cyclooxygenase-2 (COX-2) expression and prostaglandin E2 (PGE2) production in stimulated human articular chondrocytes. Materials and Methods: Human chondrocytes were derived from OA articular cartilage and treated with camel lactoferrin and then stimulated with IL-1β. Gene expression was determined by TaqMan assays and protein expression was studied by Western immunoblotting. NF-κB activity and PGE2 levels were determined by ELISA based assays. NF-κB activity was also determined by treatment of chondrocytes with NF-κB specific inhibitor Bay 11–7082. Results: Lactoferrin inhibited IL-1β-induced activation and nuclear translocation of NF-κB p65 in human OA chondrocytes. Lactoferrin also inhibited mRNA/protein expression of COX-2 and production of PGE2. Moreover, Bay 11–7082 also inhibited IL-1β-induced expression of COX-2 and production of PGE2. The inhibitory effect of lactoferrin on the IL-1β induced expression of COX-2 or production of PGE2 was mediated at least in part via suppression of NF-κB activation. Conclusions: Our data determine camel lactoferrin as a novel inhibitor of IL-1β-induced activation of NF-κB signaling events and production of cartilage-degrading molecule PGE2 via inhibition of COX-2 expressions. These results may have important implications for the development of novel therapeutic strategies for the prevention/treatment of OA and other degenerative/inflammatory diseases. SUMMARY Lactoferrin shows anti-arthritic activity in IL-1β stimulated primary human chondrocytes.Lactoferrin inhibits IL-1β-induced NF-κB activation.Lactoferrin inhibits production of cartilage degrading PGE2 via inhibition of COX-2 expression. Abbreviations Used: OA: Osteoarthritis IL-1β: Interleukin-1 beta NF-κB: Nuclear factor-kappa B COX-2: cyclooxygenase-2 PGE2: prostaglandin E2 PMID:27034605

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.

Detecting Airborne Mercury by Use of Gold Nanowires

NASA Technical Reports Server (NTRS)

Ryan, Margaret; Shevade, Abhijit; Kisor, Adam; Homer, Margie; Soler, Jessica; Mung, Nosang; Nix, Megan

2009-01-01

Like the palladium chloride (PdCl2) films described in the immediately preceding article, gold nanowire sensors have been found to be useful for detecting airborne elemental mercury at concentrations on the order of parts per billion (ppb). Also like the PdCl2 films, gold nanowire sensors can be regenerated under conditions much milder than those necessary for regeneration of gold films that have been used as airborne-Hg sensors. The interest in nanowire sensors in general is prompted by the expectation that nanowires of a given material covering a given surface may exhibit greater sensitivity than does a film of the same material because nanowires have a greater surface area. In preparation for experiments to demonstrate this sensor concept, sensors were fabricated by depositing gold nanowires, variously, on microhotplate or microarray sensor substrates. In the experiments, the electrical resistances were measured while the sensors were exposed to air at a temperature of 25 C and relative humidity of about 30 percent containing mercury at various concentrations from 2 to 70 ppb (see figure). The results of this and other experiments have been interpreted as signifying that sensors of this type can detect mercury at ppb concentrations in room-temperature air and can be regenerated by exposure to clean flowing air at temperatures <40 C.

Characterisation of GaAs:Cr pixel sensors coupled to Timepix chips in view of synchrotron applications

NASA Astrophysics Data System (ADS)

Ponchut, C.; Cotte, M.; Lozinskaya, A.; Zarubin, A.; Tolbanov, O.; Tyazhev, A.

2017-12-01

In order to meet the needs of some ESRF beamlines for highly efficient 2D X-ray detectors in the 20-50 keV range, GaAs:Cr pixel sensors coupled to TIMEPIX readout chips were implemented into a MAXIPIX detector. Use of GaAs:Cr sensor material is intended to overcome the limitations of Si (low absorption) and of CdTe (fluorescence) in this energy range The GaAs:Cr sensor assemblies were characterised with both laboratory X-ray sources and monochromatic synchrotron X-ray beams. The sensor response as a function of bias voltage was compared to a theoretical model, leading to an estimation of the μτ product of electrons in GaAs:Cr sensor material of 1.6×10-4 cm2/V. The spatial homogeneity of X-ray images obtained with the sensors was measured in different irradiation conditions, showing a particular sensitivity to small variations in the incident beam spectrum. 2D-resolved elemental mapping of the sensor surface was carried out to investigate a possible relation between the noise pattern observed in X-ray images and local fluctuations in chemical composition. A scanning of the sensor response at subpixel scale revealed that these irregularities can be correlated with a distortion of the effective pixel shapes.

Modified Organosilica Core-Shell Nanoparticles for Stable pH Sensing in Biological Solutions.

PubMed

Robinson, Kye J; Huynh, Gabriel T; Kouskousis, Betty P; Fletcher, Nicholas L; Houston, Zachary H; Thurecht, Kristofer J; Corrie, Simon R

2018-04-19

Continuous monitoring using nanoparticle-based sensors has been successfully employed in complex biological systems, yet the sensors still suffer from poor long-term stability partially because of the scaffold materials chosen to date. Organosilica core-shell nanoparticles containing a mixture of covalently incorporated pH-sensitive (shell) and pH-insensitive (core) fluorophores is presented as a continuous pH sensor for application in biological media. In contrast to previous studies focusing on similar materials, we sought to investigate the sensor characteristics (dynamic range, sensitivity, response time, stability) as a function of material properties. The ratio of the fluorescence intensities at specific wavelengths was found to be highly sensitive to pH over a physiologically relevant range (4.5-8) with a response time of <100 ms, significantly faster than that of previously reported response times using silica-based particles. Particles produced stable, pH-specific signals when stored at room temperature for more than 80 days. Finally, we demonstrated that the nanosensors successfully monitored the pH of a bacterial culture over 15 h and that pH changes in the skin of mouse cadavers could also be observed via in vivo fluorescence imaging following subcutaneous injection. The understanding gained from linking sensor characteristics and material properties will inform the next generation of optical nanosensors for continuous-monitoring applications.

On the use of electrical and optical strain gauges paired to magnetostrictive patch actuators

NASA Astrophysics Data System (ADS)

Braghin, Francesco; Cinquemani, Simone; Cazzulani, Gabriele; Comolli, Lorenzo

2014-04-01

Giant Magnetostrictive Actuators (GMA) can be profitably used in application of vibration control on smart structures. In this field, the use of inertial actuators based on magnetostrictive materials has been consolidate. Such devices turn out to be very effective in applications of vibration control, since they can be easily paired with sensors able to ensure the feedback signal necessary to perform the control action. Unlike most widespread applications, this paper studies the use of patch magnetostrictive actuators. They are made of a sheet of magnetostrictive material, rigidly constrained to the structure, and wrapped in a solenoid whose purpose is to change the intensity of the magnetic field within the material itself. The challenge in the use of such devices resides in the impossibility of having co-located sensors. This limit may be exceeded by using strain gauge sensors to measure the deformation of the structure at the actuator. This work analyzes experimentally the opportunity of introducing, inside a composite material structure, both the conventional electric strain gauges and the less conventional optical sensors based on Bragg's gratings. The performance of both solutions are analyzed with particular reference to the signal to noise ratio, the resolution of the sensors, the sensitivity to variations of the electric and magnetic fields and the temperature change associated with the operation of the actuator.

Translatory shock absorber for attitude sensors

NASA Technical Reports Server (NTRS)

Vonpragenau, G. L.; Morgan, I. T., Jr.; Kirby, C. A. (Inventor)

1976-01-01

A translatory shock absorber is provided for mounting an attitude sensor thereon for isolating a sensor from translatory vibrations. The translatory shock absorber includes a hollow block structure formed as one piece to form a parallelogram. The absorber block structure includes a movable top plate for supporting the attitude sensor and a fixed base plate with opposed side plates interposed between. At the junctions of the side plates, and the base and top plates, there are provided grooves which act as flexible hinges for attenuating translatory vibrations. A damping material is supported on a pedestal which is carried on the base plate between the side plates thereof. The top of the damping material rests against the bottom surface of the top plate for eliminating the resonant peaks of vibration.

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.

Integration of Metal Oxide Nanowires in Flexible Gas Sensing Devices

PubMed Central

Comini, Elisabetta

2013-01-01

Metal oxide nanowires are very promising active materials for different applications, especially in the field of gas sensors. Advances in fabrication technologies now allow the preparation of nanowires on flexible substrates, expanding the potential market of the resulting sensors. The critical steps for the large-scale preparation of reliable sensing devices are the elimination of high temperatures processes and the stretchability of the entire final device, including the active material. Direct growth on flexible substrates and post-growth procedures have been successfully used for the preparation of gas sensors. The paper will summarize the procedures used for the preparation of flexible and wearable gas sensors prototypes with an overlook of the challenges and the future perspectives concerning this field. PMID:23955436

Capacitive proximity sensor

DOEpatents

Kronberg, James W.

1994-01-01

A proximity sensor based on a closed field circuit. The circuit comprises a ring oscillator using a symmetrical array of plates that creates an oscillating displacement current. The displacement current varies as a function of the proximity of objects to the plate array. Preferably the plates are in the form of a group of three pair of symmetric plates having a common center, arranged in a hexagonal pattern with opposing plates linked as a pair. The sensor produces logic level pulses suitable for interfacing with a computer or process controller. The proximity sensor can be incorporated into a load cell, a differential pressure gauge, or a device for measuring the consistency of a characteristic of a material where a variation in the consistency causes the dielectric constant of the material to change.

PEDOT:PSS-Based Piezo-Resistive Sensors Applied to Reinforcement Glass Fibres for in Situ Measurement during the Composite Material Weaving Process

PubMed Central

Trifigny, Nicolas; Kelly, Fern M.; Cochrane, Cédric; Boussu, François; Koncar, Vladan; Soulat, Damien

2013-01-01

The quality of fibrous reinforcements used in composite materials can be monitored during the weaving process. Fibrous sensors previously developed in our laboratory, based on PEDOT:PSS, have been adapted so as to directly measure the mechanical stress on fabrics under static or dynamic conditions. The objective of our research has been to develop new sensor yarns, with the ability to locally detect mechanical stresses all along the warp or weft yarn. This local detection is undertaken inside the weaving loom in real time during the weaving process. Suitable electronic devices have been designed in order to record in situ measurements delivered by this new fibrous sensor yarn. PMID:23959238

Development and evaluation of novel sensing materials for detecting food contamination

NASA Astrophysics Data System (ADS)

Sankaran, Sindhuja

Rapid detection of food-borne volatile organic compounds (VOCs) such as organic acids and alcohols released by bacterial pathogens is being used as an indicator for detecting bacterial contamination in food by our research group. One of our current research thrusts is to develop novel sensors that will be sensitive to specific compounds (at low operating temperature) associated with food safety. This study evaluates two approaches employed to develop sensors for detecting acid and alcohols at low concentrations. Chemoresistive and piezoelectric sensors were developed based on metal oxides and olfactory system based biomaterials, respectively to detect acetic acid, butanol, 3-methyl-1-butanol, 1-pentanol, and 1-hexanol. The metal oxide based sensors were developed by the sol-gel method. A zinc oxide (ZnO) sensor was found to be sensitive to acetic acid with lower detection limit ranging from 13-40 ppm. The three-layered dip-coated gold electrode based ZnO sensors had a LDL of 18 ppm for acetic acid detection. The ZnO-iron oxide (Fe2O3) based nanocomposite sensors were developed to detect butanol operating at 100°C. The 5% Fe/Zn mole ratio based ZnO-Fe2O3 nanocomposite sensors had high correlation coefficients (>0.90) of calibration curves, low butanol LDLs (26 +/- 7 ppm), and lower variation among the sensor responses. The ZnO and ZnO-Fe2O3 nanocomposite sensors showed potential to detect acetic acid and butanol at low concentrations, respectively at 100°C. QCM based olfactory sensors were developed from olfactory receptor and odorant binding protein based sequences to detect low concentrations of acetic acid and alcohols (3-methyl-1-butanol and 1-hexanol), respectively. The average LDLs for acetic acid as well as alcohols detection of the QCM sensors were < 5 ppm. The linear calibration curve based correlation coefficients of the QCM sensors were > 0.80. Finally, a computational simulation based peptide sequences was designed from olfactory receptors and evaluated as sensor material for the detection of alcohols at low concentrations. The results indicated that the QCM sensors exhibited a good sensitivity to 1-hexanol and 1-pentanol with the estimated LDLs in the range of 2-3 ppm and 3-5 ppm, respectively. This research work was successful in developing multiple novel sensing materials to detect alcohols and acid associated with meat contaminations at low concentrations.

Electrochemical Measurement of Atmospheric Corrosion

NASA Technical Reports Server (NTRS)

DeArmond, Anna H.; Davis, Dennis D.; Beeson, Harold D.

1999-01-01

Corrosion of Shuttle thruster components in atmospheres containing high concentrations of nitrogen tetroxide (NTO) and water is an important issue in ground operations of bipropellant systems in humid locations. Measurements of the corrosivities of NTO-containing atmospheres and the responses of different materials to these atmospheres have been accomplished using an electrochemical sensor. The sensor is composed of alternating aluminum/titanium strips separated by thin insulating layers. Under high humidity conditions a thin film of water covers the surface of the sensor. Added NTO vapor reacts with the water film to form a conductive medium and establishes a galvanic cell. The current from this cell can be integrated with respect to time and related to the corrosion activity. The surface layer formed from humid air/NTO reacts in the same way as an aqueous solution of nitric acid. Nitric acid is generally considered an important agent in NTO corrosion situations. The aluminum/titanium sensor is unresponsive to dry air, responds slightly to humid air (> 75% RH), and responds strongly to the combination of humid air and NTO. The sensor response is a power function (n = 2) of the NTO concentration. The sensor does not respond to NTO in dry air. The response of other materials in this type of sensor is related to position of the material in a galvanic series in aqueous nitric acid. The concept and operation of this electrochemical corrosion measurement is being applied to other corrosive atmospheric contaminants such as hydrogen chloride, hydrogen fluoride, sulfur dioxide, and acidic aerosols.

Cybernetic systems based on inductive logic

NASA Astrophysics Data System (ADS)

Fry, Robert L.

2001-05-01

Recent work in the area of inductive logic suggests that cybernetics might be quantified and reduced to engineering practice. If so, then there are considerable implications for engineering, science, and other fields. This paper attempts to capture the essential ideas of cybernetics cast in the light of inductive logic. The described inductive logic extends conventional logic by adding a conjugate logical domain of questions to the logical domain of assertions intrinsic to Boolean Algebra with which most are familiar. This was first posited and developed by Richard Cox. Interestingly enough, these two logical domains, one of questions and the other of assertions, only exist relative to one another with each possessing natural measures of entropy and probability, respectively. Examples are given that highlight the utility of cybernetic approaches to neuroscience, algorithm design, system engineering, and the design and understanding of defensive and offensive systems. For example, the application of cybernetic approaches to defense systems suggests that these systems possess a wavefunction which like quantum mechanics, collapses when we ``look'' through the eyes of the system sensors such as radars and optical sensors. .

One year Survival Rate of Ketac Molar versus Vitro Molar for Occlusoproximal ART Restorations: a RCT.

PubMed

Anna Luisa de Brito, Pacheco; Isabel Cristina, Olegário; Clarissa Calil, Bonifácio; Ana Flávia Bissoto, Calvo; José Carlos Pettorossi, Imparato; Daniela Prócida, Raggio

2017-11-06

Good survival rates for single-surface Atraumatic Restorative Treatment (ART) restorations have been reported, while multi-surface ART restorations have not shown similar results. The aim of this study was to evaluate the survival rate of occluso-proximal ART restorations using two different filling materials: Ketac Molar EasyMix (3M ESPE) and Vitro Molar (DFL). A total of 117 primary molars with occluso-proximal caries lesions were selected in 4 to 8 years old children in Barueri city, Brazil. Only one tooth was selected per child. The subjetcs were randomly allocated in two groups according to the filling material. All treatments were performed following the ART premises and all restorations were evaluated after 2, 6 and 12 months. Restoration survival was evaluated using Kaplan-Meier survival analysis and Log-rank test, while Cox regression analysis was used for testing association with clinical factors (α = 5%). There was no difference in survival rate between the materials tested, (HR = 1.60, CI = 0.98-2.62, p = 0.058). The overall survival rate of restorations was 42.74% and the survival rate per group was Ketac Molar = 50,8% and Vitro Molar G2 = 34.5%). Cox regression test showed no association between the analyzed clinical variables and the success of the restorations. After 12 months evaluation, no difference in the survival rate of ART occluso-proximal restorations was found between tested materials.

Flexible and self-powered temperature-pressure dual-parameter sensors using microstructure-frame-supported organic thermoelectric materials.

PubMed

Zhang, Fengjiao; Zang, Yaping; Huang, Dazhen; Di, Chong-an; Zhu, Daoben

2015-09-21

Skin-like temperature- and pressure-sensing capabilities are essential features for the next generation of artificial intelligent products. Previous studies of e-skin and smart elements have focused on flexible pressure sensors, whereas the simultaneous and sensitive detection of temperature and pressure with a single device remains a challenge. Here we report developing flexible dual-parameter temperature-pressure sensors based on microstructure-frame-supported organic thermoelectric (MFSOTE) materials. The effective transduction of temperature and pressure stimuli into two independent electrical signals permits the instantaneous sensing of temperature and pressure with an accurate temperature resolution of <0.1 K and a high-pressure-sensing sensitivity of up to 28.9 kPa(-1). More importantly, these dual-parameter sensors can be self-powered with outstanding sensing performance. The excellent sensing properties of MFSOTE-based devices, together with their unique advantages of low cost and large-area fabrication, make MFSOTE materials possess promising applications in e-skin and health-monitoring elements.

Design and Performance of a Metal-Shielded Piezoelectric Sensor

PubMed Central

Sáenz de Inestrillas, Álvaro; Camarena, Francisco; Bou Cabo, Manuel; Barreiro, Julián M.; Reig, Antonio

2017-01-01

In certain circumstances when acoustic measurements are required in the presence of explosive atmospheres the sensor must be placed inside a Faraday Cage. Piezoelectric active materials are suitable for this purpose as they do not need an electrical power supply, although the metal shielding can considerably reduce sensor sensitivity, which is already low at the acoustic frequency range (<20 kHz). This paper describes a metal-shielded piezoelectric sensor designed to work in the range of frequencies between 1 and 2 kHz and in these environmental conditions. The main idea was to add a thin material layer to the front face of the piezoelectric ceramic in order to force the system to vibrate in flexure mode at low frequencies. The resonant frequency and sensitivity of the system was studied as a function of the radius, thickness, and material of the thin layer. The study includes a comparison of theoretical model, FEM simulation, and real data measured using three aluminum and three steel prototypes of different sizes. PMID:28587224

Design and Performance of a Metal-Shielded Piezoelectric Sensor.

PubMed

Sáenz de Inestrillas, Álvaro; Camarena, Francisco; Bou Cabo, Manuel; Barreiro, Julián M; Reig, Antonio

2017-06-04

In certain circumstances when acoustic measurements are required in the presence of explosive atmospheres the sensor must be placed inside a Faraday Cage. Piezoelectric active materials are suitable for this purpose as they do not need an electrical power supply, although the metal shielding can considerably reduce sensor sensitivity, which is already low at the acoustic frequency range (<20 kHz). This paper describes a metal-shielded piezoelectric sensor designed to work in the range of frequencies between 1 and 2 kHz and in these environmental conditions. The main idea was to add a thin material layer to the front face of the piezoelectric ceramic in order to force the system to vibrate in flexure mode at low frequencies. The resonant frequency and sensitivity of the system was studied as a function of the radius, thickness, and material of the thin layer. The study includes a comparison of theoretical model, FEM simulation, and real data measured using three aluminum and three steel prototypes of different sizes.

Superconductivity Devices: Commercial Use of Space

NASA Technical Reports Server (NTRS)

Haertling, Gene (Principal Investigator); Furman, Eugene; Li, Guang

1996-01-01

The work described in this report covers various aspects of the Rainbow solid-state actuator and sensor technologies. It is presented in five parts dealing with sensor applications, nonlinear properties, stress-optic and electrooptic properties, stacks and arrays, and publications. The Rainbow actuator technology is a relatively new materials development which had its inception in 1992. It involves a new processing technique for preparing pre-stressed, high lead containing piezoelectric and electrostrictive ceramic materials. Ceramics fabricated by this method produce bending-mode actuator devices which possess several times more displacement and load bearing capacity than present-day benders. Since they can also be used in sensor applications, Rainbows are part of the family of materials known as smart ceramics. During this period, PLZT Rainbow ceramics were characterized with respect to their piezoelectric properties for potential use in stress sensor applications. Studies of the nonlinear and stress-optic/electrooptic birefringent properties were also initiated during this period. Various means for increasing the utility of stress-enhanced Rainbow actuators are presently under investigation.

Flexible and self-powered temperature-pressure dual-parameter sensors using microstructure-frame-supported organic thermoelectric materials

NASA Astrophysics Data System (ADS)

Zhang, Fengjiao; Zang, Yaping; Huang, Dazhen; di, Chong-An; Zhu, Daoben

2015-09-01

Skin-like temperature- and pressure-sensing capabilities are essential features for the next generation of artificial intelligent products. Previous studies of e-skin and smart elements have focused on flexible pressure sensors, whereas the simultaneous and sensitive detection of temperature and pressure with a single device remains a challenge. Here we report developing flexible dual-parameter temperature-pressure sensors based on microstructure-frame-supported organic thermoelectric (MFSOTE) materials. The effective transduction of temperature and pressure stimuli into two independent electrical signals permits the instantaneous sensing of temperature and pressure with an accurate temperature resolution of <0.1 K and a high-pressure-sensing sensitivity of up to 28.9 kPa-1. More importantly, these dual-parameter sensors can be self-powered with outstanding sensing performance. The excellent sensing properties of MFSOTE-based devices, together with their unique advantages of low cost and large-area fabrication, make MFSOTE materials possess promising applications in e-skin and health-monitoring elements.

Dynamic potential and surface morphology study of sertraline membrane sensors

PubMed Central

Khater, M.M.; Issa, Y.M.; Hassib, H.B.; Mohammed, S.H.

2014-01-01

New rapid, sensitive and simple electrometric method was developed to determine sertraline hydrochloride (Ser-Cl) in its pure raw material and pharmaceutical formulations. Membrane sensors based on heteropolyacids as ion associating material were prepared. Silicomolybdic acid (SMA), silicotungstic acid (STA) and phosphomolybdic acid (PMA) were used. The slope and limit of detection are 50.00, 60.00 and 53.24 mV/decade and 2.51, 5.62 and 4.85 μmol L−1 for Ser-ST, Ser-PM and Ser-SM membrane sensors, respectively. Linear range is 0.01–10.00 for the three sensors. These new sensors were used for the potentiometric titration of Ser-Cl using sodium tetraphenylborate as titrant. The surface morphologies of the prepared membranes with and without the modifier (ion-associate) were studied using scanning and atomic force microscopes. PMID:26257944

Biomimetic virus-based colourimetric sensors.

PubMed

Oh, Jin-Woo; Chung, Woo-Jae; Heo, Kwang; Jin, Hyo-Eon; Lee, Byung Yang; Wang, Eddie; Zueger, Chris; Wong, Winnie; Meyer, Joel; Kim, Chuntae; Lee, So-Young; Kim, Won-Geun; Zemla, Marcin; Auer, Manfred; Hexemer, Alexander; Lee, Seung-Wuk

2014-01-01

Many materials in nature change colours in response to stimuli, making them attractive for use as sensor platform. However, both natural materials and their synthetic analogues lack selectivity towards specific chemicals, and introducing such selectivity remains a challenge. Here we report the self-assembly of genetically engineered viruses (M13 phage) into target-specific, colourimetric biosensors. The sensors are composed of phage-bundle nanostructures and exhibit viewing-angle independent colour, similar to collagen structures in turkey skin. On exposure to various volatile organic chemicals, the structures rapidly swell and undergo distinct colour changes. Furthermore, sensors composed of phage displaying trinitrotoluene (TNT)-binding peptide motifs identified from a phage display selectively distinguish TNT down to 300 p.p.b. over similarly structured chemicals. Our tunable, colourimetric sensors can be useful for the detection of a variety of harmful toxicants and pathogens to protect human health and national security.

Biomimetic virus-based colourimetric sensors

NASA Astrophysics Data System (ADS)

Oh, Jin-Woo; Chung, Woo-Jae; Heo, Kwang; Jin, Hyo-Eon; Lee, Byung Yang; Wang, Eddie; Zueger, Chris; Wong, Winnie; Meyer, Joel; Kim, Chuntae; Lee, So-Young; Kim, Won-Geun; Zemla, Marcin; Auer, Manfred; Hexemer, Alexander; Lee, Seung-Wuk

2014-01-01

Many materials in nature change colours in response to stimuli, making them attractive for use as sensor platform. However, both natural materials and their synthetic analogues lack selectivity towards specific chemicals, and introducing such selectivity remains a challenge. Here we report the self-assembly of genetically engineered viruses (M13 phage) into target-specific, colourimetric biosensors. The sensors are composed of phage-bundle nanostructures and exhibit viewing-angle independent colour, similar to collagen structures in turkey skin. On exposure to various volatile organic chemicals, the structures rapidly swell and undergo distinct colour changes. Furthermore, sensors composed of phage displaying trinitrotoluene (TNT)-binding peptide motifs identified from a phage display selectively distinguish TNT down to 300 p.p.b. over similarly structured chemicals. Our tunable, colourimetric sensors can be useful for the detection of a variety of harmful toxicants and pathogens to protect human health and national security.

Development of an IrO x micro pH sensor array on flexible polymer substrate

NASA Astrophysics Data System (ADS)

Huang, Wen-Ding; Wang, Jianqun; Ativanichayaphong, Thermpon; Chiao, Mu; Chiao, J. C.

2008-03-01

pH sensor is an essential component used in many chemical, food, and bio-material industries. Conventional glass electrodes have been used to construct pH sensors, however, have some disadvantages in specific applications. It is difficult to use glass electrodes for in vivo biomedical or food monitoring applications due to size limitation and no deformability. In this paper, we present design and fabrication processes of a miniature iridium oxide thin film pH sensor array on flexible polymer substrates. The amorphous iridium oxide thin film was used as the sensing material. A sol-gel dip-coating process of iridium oxide film was demonstrated in this paper. A super-Nernstian response has been measured on individual sensors of the array with a slope of -71.6+/-3 mV/pH at 25°C within the pH range between 2.83 and 11.04.

A resonant force sensor based on ionic polymer metal composites

NASA Astrophysics Data System (ADS)

Bonomo, Claudia; Fortuna, Luigi; Giannone, Pietro; Graziani, Salvatore; Strazzeri, Salvatore

2008-02-01

In this paper a novel force sensor, based on ionic polymer metal composites (IPMCs), is presented. The system has DC sensing capabilities and is able to work in the range of a few millinewtons. IPMCs are emerging materials used to realize motion actuators and sensors. An IPMC strip is activated in a beam fixed/simply-supported configuration. The beam is tightened at the simply-supported end by a force. This influences the natural resonant frequency of the beam; the value of the resonant frequency is used in the proposed system to estimate the force applied in the axial direction. The performance of the system based on the IPMC material has proved to be comparable with that of sensors based on other sensing mechanisms. This suggests the possibility of using this class of polymeric devices to realize PMEMS (plastic micro electrical mechanical systems) sensors.

COX-1 vs. COX-2 as a determinant of basal tone in the internal anal sphincter

PubMed Central

de Godoy, Márcio A. F.; Rattan, Neeru; Rattan, Satish

2009-01-01

Prostanoids, produced endogenously via cyclooxygenases (COXs), have been implicated in the sustained contraction of different smooth muscles. The two major types of COXs are COX-1 and COX-2. The COX subtype involved in the basal state of the internal anal sphincter (IAS) smooth muscle tone is not known. To identify the COX subtype, we examined the effect of COX-1- and COX-2-selective inhibitors, SC-560 and rofecoxib, respectively, on basal tone in the rat IAS. We also determined the effect of selective deletion of COX-1 and COX-2 genes (COX-1−/− and COX-2−/− mice) on basal tone in murine IAS. Our data show that SC-560 causes significantly more efficacious and potent concentration-dependent decreases in IAS tone than rofecoxib. In support of these data, significantly higher levels of COX-1 than COX-2 mRNA were found in the IAS. In addition, higher levels of COX-1 mRNA and protein were expressed in rat IAS than rectal smooth muscle. In wild-type mice, IAS tone was decreased 41.4 ± 3.4% (mean ± SE) by SC-560 (1 × 10−5 M) and 5.4 ± 2.2% by rofecoxib (P < 0.05, n = 5). Basal tone was 0.172 ± 0.021 mN//mg in the IAS from wild-type mice and significantly less (0.080 ± 0.015 mN/mg) in the IAS from COX-1−/− mice (P < 0.05, n = 5). However, basal tone in COX-2−/− mice was not significantly different from that in wild-type mice. We conclude that COX-1-related products contribute significantly to IAS tone. PMID:19056763

COX-1 vs. COX-2 as a determinant of basal tone in the internal anal sphincter.

PubMed

de Godoy, Márcio A F; Rattan, Neeru; Rattan, Satish

2009-02-01

Prostanoids, produced endogenously via cyclooxygenases (COXs), have been implicated in the sustained contraction of different smooth muscles. The two major types of COXs are COX-1 and COX-2. The COX subtype involved in the basal state of the internal anal sphincter (IAS) smooth muscle tone is not known. To identify the COX subtype, we examined the effect of COX-1- and COX-2-selective inhibitors, SC-560 and rofecoxib, respectively, on basal tone in the rat IAS. We also determined the effect of selective deletion of COX-1 and COX-2 genes (COX-1(-/-) and COX-2(-/-) mice) on basal tone in murine IAS. Our data show that SC-560 causes significantly more efficacious and potent concentration-dependent decreases in IAS tone than rofecoxib. In support of these data, significantly higher levels of COX-1 than COX-2 mRNA were found in the IAS. In addition, higher levels of COX-1 mRNA and protein were expressed in rat IAS than rectal smooth muscle. In wild-type mice, IAS tone was decreased 41.4 +/- 3.4% (mean +/- SE) by SC-560 (1 x 10(-5) M) and 5.4 +/- 2.2% by rofecoxib (P < 0.05, n = 5). Basal tone was 0.172 +/- 0.021 mN//mg in the IAS from wild-type mice and significantly less (0.080 +/- 0.015 mN/mg) in the IAS from COX-1(-/-) mice (P < 0.05, n = 5). However, basal tone in COX-2(-/-) mice was not significantly different from that in wild-type mice. We conclude that COX-1-related products contribute significantly to IAS tone.

Electrostatics with Computer-Interfaced Charge Sensors

ERIC Educational Resources Information Center

Morse, Robert A.

2006-01-01

Computer interfaced electrostatic charge sensors allow both qualitative and quantitative measurements of electrostatic charge but are quite sensitive to charges accumulating on modern synthetic materials. They need to be used with care so that students can correctly interpret their measurements. This paper describes the operation of the sensors,…

Imaging optical sensor arrays.

PubMed

Walt, David R

2002-10-01

Imaging optical fibres have been etched to prepare microwell arrays. These microwells have been loaded with sensing materials such as bead-based sensors and living cells to create high-density sensor arrays. The extremely small sizes and volumes of the wells enable high sensitivity and high information content sensing capabilities.

Electronic Sensors: Making the Connection

ERIC Educational Resources Information Center

Johnson, Richard T.; Cotton, Samuel E.

2008-01-01

For educational purposes it is not necessary to use expensive commercial-grade equipment to teach students about commonly used sensors. Schools frequently have limited funds for acquiring educational materials; therefore, purchasing sensors identical to those used in large-scale industry is not an option. By purchasing small-scale components that…

Pyrolyzed-parylene based sensors and method of manufacture

NASA Technical Reports Server (NTRS)

Tai, Yu-Chong (Inventor); Liger, Matthieu (Inventor); Miserendino, Scott (Inventor); Konishi, Satoshi (Inventor)

2007-01-01

A method (and resulting structure) for fabricating a sensing device. The method includes providing a substrate comprising a surface region and forming an insulating material overlying the surface region. The method also includes forming a film of carbon based material overlying the insulating material and treating to the film of carbon based material to pyrolyzed the carbon based material to cause formation of a film of substantially carbon based material having a resistivity ranging within a predetermined range. The method also provides at least a portion of the pyrolyzed carbon based material in a sensor application and uses the portion of the pyrolyzed carbon based material in the sensing application. In a specific embodiment, the sensing application is selected from chemical, humidity, piezoelectric, radiation, mechanical strain or temperature.

Conductive fiber-based ultrasensitive textile pressure sensor for wearable electronics.

PubMed

Lee, Jaehong; Kwon, Hyukho; Seo, Jungmok; Shin, Sera; Koo, Ja Hoon; Pang, Changhyun; Son, Seungbae; Kim, Jae Hyung; Jang, Yong Hoon; Kim, Dae Eun; Lee, Taeyoon

2015-04-17

A flexible and sensitive textile-based pressure sensor is developed using highly conductive fibers coated with dielectric rubber materials. The pressure sensor exhibits superior sensitivity, very fast response time, and high stability, compared with previous textile-based pressure sensors. By using a weaving method, the pressure sensor can be applied to make smart gloves and clothes that can control machines wirelessly as human-machine interfaces. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Handheld chemiresistive gas sensor readout system

NASA Astrophysics Data System (ADS)

Joubert, Trudi-Heleen; du Toit, Jurie; Mkwakikunga, Bonex; Bosscha, Peter

2016-02-01

Low-cost and non-invasive diabetes diagnosis is increasingly important [1], and this paper presents a handheld readout system for chemiresistive gas sensors in a breath acetone diagnostic application. The sensor contains reference and detection devices, used for the detection of gas concentration. Fabrication is by dropcasting a metaloxide nanowire solution onto gold interdigitated electrodes, which had been manufactured on silicon. The resulting layer is a wide bandgap n-type semiconductor material sensitive to acetone, producing a change in resistance between the electrode terminals [2]. Chemiresistive sensors typically require temperatures of 300-500 °C, while variation of sensing temperature is also employed for selective gas detection. The nano-structured functional material requires low temperatures due to large surface area, but heating is still required for acceptable recovery kinetics. Furthermore, UV illumination improves the sensor recovery [3], and is implemented in this system. Sensor resistances range from 100 Ω to 50 MΩ, while the sensor response time require a sampling frequency of 10Hz. Sensor resistance depends on temperature, humidity, and barometric pressure. The GE CC2A23 temperature sensor is used over a range of -10°C to 60°C, the Honeywell HIH5031 humidity sensor operates up to 85% over this temperature range, and the LPS331AP barometric pressure sensor measures up to 1.25 bar. Honeywell AWM43300V air flow sensors monitor the flow rate up to 1000 sccm. An LCD screen displays all the sensor data, as well as real time date and time, while all measurements are also logged in CSV-format. The system operates from a rechargeable battery.

The Modification of Fuel Cell-Based Breath Alcohol Sensor Materials to Improve Water Retention of Sensing Performance

NASA Astrophysics Data System (ADS)

Allan, Jesse

Fuel cell based breath alcohol sensors (BrASs) are one of the most important tools used by law enforcement today. The ability to screen potentially intoxicated subjects with the ease, speed, and flexibility the BrAS can provide is unmatched by any other device of its kind. While these devices are used globally, they all suffer from a common deficiency: reliance on water. The ability of the fuel cell sensor to manage water content is one of the greatest fundamental challenges facing this technology today. In order to evaluate the fuel cell sensor device, a methodology was required that would allow in-house sensor testing to be coupled with a diagnostic testing method to not only test materials sensing performance, but also determine why a sensor behaved how it did. To do this, a next-generation fuel cell was designed specifically for sensor testing along with a test station that allowed for rapid response and sensor characteristics of a given material. The fuel cell was designed to allow in-situ testing of a membrane electrode assembly (MEA) of interest using cyclic voltammetry and electrochemical impedance spectroscopy. The in-house design was validated against a commercial cell to provide feedback on how materials in the in-house cell would behave in a commercial designed unit. The results showed that our cell with a commercial MEA behaved identically to a commercial cell with the same MEA. Following validation of our cell, common membrane materials were investigated to identify their suitability in a senor role. The materials chosen were designed for power generating devices, so they provided a benchmark to identify which properties would be important for sensor operation. It was found that while the Nafion membrane and sulfonated poly (ether ether ketone) did show performance increases over the commercial MEA, the thin characteristics of these membranes limited performance in drier conditions. From these results, it was determined that thicker membrane materials are better suited for sensor applications. The commercially used porous poly-vinyl chloride (PVC) membrane was investigated and modified to improve performance of this material. As PVC does not contain any natural hydroscopic properties, the addition of various hydrophilic groups to the PVC would aid in water management. It was found that while chemical modification could improve water retention, optimization of the modifications would be required to ensure flooding was not an issue. Composites of PVC and sulfonated silica showed performance that matched that of the commercial PVC, whilst using significantly less water to achieve those results. By reducing the water required for sensing, leaching of acid, as well as flooding could be reduced. Finally, the catalyst layer and gas diffusion layer (GDL) were investigated to understand what properties of these would impart the best performance increases for the sensor. For the catalyst layer, it was found that platinum black and 20% platinum supported on carbon achieved similar results. Platinum black has excellent catalytic activity for the ethanol oxidation reaction, while the surface area of the 20% platinum supported on carbon would allow for more ethanol to react, increasing the overall sensor capability. The choice of catalyst was less of an issue than the choice of GDL. It was found that using carbon fiber paper GDLs lead to greater retention of water in the MEA compared to carbon cloth GDLs due to the lower air permeability. This came at a cost however in that with a lower air permeability, less ethanol vapour would reach the catalytic sites, reducing sensing performance. Depending on the choice of membrane, removal of the GDL could impart performance increases, but could also cause detrimental failure in the case of Nafion based systems.

Smart fiber-reinforced polymer anchorage system with optical fiber Bragg grating sensors

NASA Astrophysics Data System (ADS)

Huang, Minghua; Zhou, Zhi; He, Jianping; Chen, Genda; Ou, Jinping

2010-03-01

Civil Engineers have used fiber reinforced polymer (FRP) with high axial strength as an effective and economical alternative to steel in harsh corrosion environments. However, the practical applications of FRP are limited by the tendency of FRP materials to fail suddenly under lateral pressure and surface injury. For example, shear stresses result from the bonding effect between the FRP material and the structure of the anchorage system due to the lower shear strength of FRP. This paper proposes a novel smart FRP anchorage system with embedded optical fiber Bragg grating (FBG) sensors to monitor the axial strain state and accordingly the interfacial shear stress, as well as the interfacial damage characteristics of FRP anchorage. One FBG sensor was embedded in an FRP rod outside the anchorage region to evaluate the properties of the material, and seven FBG sensors were distributed along the rod in the anchor to monitor the axial strain variations and study the interfacial mechanical behaviors of the smart FRP anchorage under a static pulling load. The experimental results agreed well with theoretical predictions. The smart FRP anchorage system with optical FBG sensors proves effective and practical for monitoring the long-term mechanical behavior of FRP anchorage systems.

Investigation into the use of microwave sensors to monitor particulate manufacturing processes

NASA Astrophysics Data System (ADS)

Austin, John Samuel, III

Knowledge of a material's properties in-line during manufacture is of critical importance to many industries, including the pharmaceutical industry, and can be used for either process or quality control. Different microwave sensor configurations were tested to determine both the moisture content and the bulk density in pharmaceutical powders during processing on-line. Although these parameters can significantly affect a material's flowability, compressibility, and cohesivity, in the presence of blends, the picture is incomplete. Due to the ease with which particulate blends tend to segregate, blend uniformity and chemical composition are two critical parameters in nearly all solids manufacturing industries. The prevailing wisdom has been that microwave sensors are not capable of or sensitive enough to measure the relative concentrations of components in a blend. Consequently, it is common to turn to near infrared sensing to determine material composition on-line. In this study, a novel microwave sensor was designed and utilized to determine, separately, the concentrations of different components in a blend of pharmaceutical powders. This custom microwave sensor was shown to have comparable accuracy to the state-of-the-art for both chemical composition and moisture content determination.

Optical fiber evanescent absorption sensors for high-temperature gas sensing in advanced coal-fired power plants

NASA Astrophysics Data System (ADS)

Buric, Michael P.; Ohodnicky, Paul R.; Duy, Janice

2012-10-01

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

Potency and selectivity of carprofen enantiomers for inhibition of bovine cyclooxygenase in whole blood assays.

PubMed

Brentnall, Claire; Cheng, Zhangrui; McKellar, Quintin A; Lees, Peter

2012-12-01

Whole blood in vitro assays were used to determine the potency and selectivity of carprofen enantiomers for inhibition of the isoforms of cyclooxygenase (COX), COX-1 and COX-2, in the calf. S(+)-carprofen possessed preferential activity for COX-2 inhibition but, because the slopes of inhibition curves differed, the COX-1:COX-2 inhibition ratio decreased from 9.04:1 for inhibitory concentration (IC)10 to 1.84:1 for IC95. R(-) carprofen inhibited COX-2 preferentially only for low inhibition of the COX isoforms (IC10 COX-1:COX-2=6.63:1), whereas inhibition was preferential for COX-1 for a high level of inhibition (IC95 COX-1:COX-2=0.20:1). S(+) carprofen was the more potent inhibitor of COX isoforms; potency ratios S(+):R(-) carprofen were 11.6:1 for IC10 and 218:1 for IC90. Based on serum concentrations of carprofen enantiomers obtained after administration of a therapeutic dose of 1.4 mg/kg to calves subcutaneously, S(+)-carprofen concentrations exceeded the in vitro IC80 COX-2 value for 32 h and the IC20 for COX-1 for 33 h. The findings are discussed in relation to efficacy and safety of carprofen in calves. Copyright © 2012 Elsevier Ltd. All rights reserved.

Fractals and self-organized criticality in anti-inflammatory drugs

NASA Astrophysics Data System (ADS)

Phillips, J. C.

2014-12-01

Nonsteroidal anti-inflammatory drugs (NSAIDs) act through inhibiting prostaglandin synthesis, a catalytic activity possessed by two distinct cyclooxygenase (COX-1 and COX-2) isozymes encoded by separate genes. The discovery of COX-2 launched a new era in NSAID pharmacology, resulting in the synthesis, marketing, and widespread use of COX-2 selective inhibitors. Extensive structural studies of the biology of prostaglandin synthesis and inhibition have explained some of the differences between COX-1 and COX-2 functionality, but others are still unexplained. Notably these include molecular differences that cause COX-1 inhibitors to produce a slight decrease, and COX-2 inhibitors to induce a significant increase, in heart attacks and strokes. These differences were unexpected because of the 60% overall COX-1 and COX-2 sequence similarity and the 1-2 conservation of catalytic sites. Hydropathic analysis shows important bicyclic differences between COX-1 and COX-2 on a large scale outside the catalytic pocket. These differences involve much stronger amphiphilic interactions in COX-2 than in COX-1, and may explain the selective antiplatelet effectiveness of COX-2. Success of the non-Euclidean structural analysis is the result of using the new Brazilian hydropathicity scale based on self-organized criticality (SOC) of universal protein modules.

Constitutively expressed COX-2 in osteoblasts positively regulates Akt signal transduction via suppression of PTEN activity.

PubMed

Li, Ching-Ju; Chang, Je-Ken; Wang, Gwo-Jaw; Ho, Mei-Ling

2011-02-01

Cyclooxygenase-2 (COX-2) is thought to be an inducible enzyme, but increasing reports indicate that COX-2 is constitutively expressed in several organs. The status of COX-2 expression in bone and its physiological role remains undefined. Non-selective non-steroidal anti-inflammatory drugs (NSAIDs) and selective COX-2 inhibitors, which commonly suppress COX-2 activity, were reported to suppress osteoblast proliferation via Akt/FOXO3a/p27(Kip1) signaling, suggesting that COX-2 may be the key factor of the suppressive effects of NSAIDs on proliferation. Although Akt activation correlates with PTEN deficiency and cell viability, the role of COX-2 on PTEN/Akt regulation remains unclear. In this study, we hypothesized that COX-2 may be constitutively expressed in osteoblasts and regulate PTEN/Akt-related proliferation. We examined the localization and co-expression of COX-2 and p-Akt in normal mouse femurs and in cultured mouse (mOBs) and human osteoblasts (hOBs). Our results showed that osteoblasts adjacent to the trabeculae, periosteum and endosteum in mouse femurs constitutively expressed COX-2, while COX-2 co-expressed with p-Akt in osteoblasts sitting adjacent to trabeculae in vivo, and in mOBs and hOBs in vitro. We further used COX-2 siRNA to test the role of COX-2 in Akt signaling in hOBs; COX-2 silencing significantly inhibited PTEN phosphorylation, enhanced PTEN activity, and suppressed p-Akt level and proliferation. However, replenishment of the COX-2 enzymatic product, PGE2, failed to reverse COX-2-dependent Akt phosphorylation. Furthermore, transfection with recombinant human COX-2 (rhCOX-2) significantly reversed COX-2 siRNA-suppressed PTEN phosphorylation, but this effect was reduced when the enzymatic activity of rhCOX-2 was blocked. This finding indicated that the effect of COX-2 on PTEN/Akt signaling is not related to PGE2 but still dependent on COX-2 enzymatic activity. Conversely, COX-1 silencing did not affect PTEN/Akt signaling. Our findings provide new insight into bone physiology; namely, that COX-2 is constitutively expressed in osteoblasts in the dynamic bone growth area, which facilitates osteoblast proliferation via PTEN/Akt/p27(Kip1) signaling. Copyright © 2010 Elsevier Inc. All rights reserved.

Detection of Electrophilic and Nucleophilic Chemical Agents

DOEpatents

McElhanon, James R.; Shepodd, Timothy J.

2008-11-11

A "real time" method for detecting electrophilic and nucleophilic species generally by employing tunable, precursor sensor materials that mimic the physiological interaction of these agents to form highly florescent berberine-type alkaloids that can be easily and rapidly detected. These novel precursor sensor materials can be tuned for reaction with both electrophilic (chemical species, toxins) and nucleophilic (proteins and other biological molecules) species.

Designing cellulosic and nanocellulosic sensors for interface with a protease sequestrant wound-dressing prototype: implications of material selection for dressing and protease sensor design

USDA-ARS?s Scientific Manuscript database

An intelligent dressing is a self-adjusting material with multifunctional properties and/or a biosensor-interface designed to treat specific pathological issues of wounds at a molecular or cellular level. The ability to detect and treat excessive protease levels in wounds, one indicator of chronic w...

Bionanomaterials and Bioinspired Nanostructures for Selective Vapor Sensing

NASA Astrophysics Data System (ADS)

Potyrailo, Radislav; Naik, Rajesh R.

2013-07-01

At present, monitoring of air at the workplace, in urban environments, and on battlefields; exhaled air from medical patients; air in packaged food containers; and so forth can be accomplished with different types of analytical instruments. Vapor sensors have their niche in these measurements when an unobtrusive, low-power, and cost-sensitive technical solution is required. Unfortunately, existing vapor sensors often degrade their vapor-quantitation accuracy in the presence of high levels of interferences and cannot quantitate several components in complex gas mixtures. Thus, new sensing approaches with improved sensor selectivity are required. This technological task can be accomplished by the careful design of sensing materials with new performance properties and by coupling these materials with the suitable physical transducers. This review is focused on the assessment of the capabilities of bionanomaterials and bioinspired nanostructures for selective vapor sensing. We demonstrate that these sensing materials can operate with diverse transducers based on electrical, mechanical, and optical readout principles and can provide vapor-response selectivity previously unattainable by using other sensing materials. This ability for selective vapor sensing provides opportunities to significantly impact the major directions in development and application scenarios of vapor sensors.

Metal-Organic Framework with Aromatic Rings Tentacles: High Sulfur Storage in Li-S Batteries and Efficient Benzene Homologues Distinction.

PubMed

Li, Meng-Ting; Sun, Yu; Zhao, Kai-Sen; Wang, Zhao; Wang, Xin-Long; Su, Zhong-Min; Xie, Hai-Ming

2016-12-07

We designed and fabricated a fluorophore-containing tetradentate carboxylate ligand-based metal-organic framework (MOF) material with open and semiopen channels, which acted as the host for sulfur trapped in Li-S batteries and sensor of benzene homologues. These channels efficiently provide a π-π* conjugated matrix for the charge transfer and guest molecule trapping. The open channel ensured a much higher loading quantitative of sulfur (S content-active material, 72 wt %; electrode, 50.4 wt %) than most of the MOF/sulfur composites, while the semiopen channel possessing aromatic rings tentacles guaranteed an outstanding specific discharge capacity (1092 mA h g -1 at 0.1 C) accompanied by good cycling stability. To our surprise, benefiting from special π-π* conjugated conditions, compound 1 could be a chemical sensor for benzene homologues, especially for 1,2,4-trimethylbenzene (1,2,4-TMB). This is the first example of MOFs materials serving as a sensor of 1,2,4-TMB among benzene homologues. Our works may be worthy of use for references in other porous materials systems to manufacture more long-acting Li-S batteries and sensitive chemical sensors.

On the Effects of the Lateral Strains on the Fiber Bragg Grating Response

PubMed Central

Lai, Marco; Karalekas, Dimitris; Botsis, John

2013-01-01

In this paper, a combined experimental-numerical based work was undertaken to investigate the Bragg wavelength shift response of an embedded FBG sensor when subjected to different conditions of multi-axial loading (deformation). The following cases are examined: (a) when an isotropic host material with no constrains on planes normal to the embedded sensor's axis is biaxially loaded, (b) when the same isotropic host material is subjected to hydrostatic pressure and (c) when the hydrostatically loaded host material is an anisotropic one, as in the case of a composite material, where the optical fiber is embedded along the reinforcing fibers. The comparison of the experimental results and the finite element simulations shows that, when the axial strain on the FBG sensor is the dominant component, the standard wavelength-shift strain relation can be used even if large lateral strains apply on the sensor. However when this is not the case, large errors may be introduced in the conversion of the wavelength to axial strains on the fiber. This situation arises when the FBG is placed parallel to high modulus reinforcing fibers of a polymer composite. PMID:23429580

Threshold temperature optical fibre sensors

NASA Astrophysics Data System (ADS)

Stasiewicz, K. A.; Musial, J. E.

2016-12-01

This paper presents a new approach to manufacture a threshold temperature sensor based on a biconical optical fibre taper. The presented sensor employs the influence of variable state of concentration of some isotropic materials like wax or paraffin. Application of the above- mentioned materials is an attempt to prove that there is a possibility to obtain a low-cost, repeatable and smart sensor working as an in-line element. Optical fibre taper was obtained from a standard single mode fibre (SMF28®) by using a low pressure gas burner technique. The diameter of the manufactured tapers was 6.0 ± 0.5 μm with the length of elongation equal to 30.50 ± 0.16 mm. The applied technology allowed to produce tapers with the losses of 0.183 ± 0.015 dB. Application of materials with different temperature transition points made it possible to obtain the threshold work at the temperatures connected directly with their conversion temperature. External materials at the temperatures above their melting points do not influence the propagation losses. For each of them two types of the protection area and position of the optical fibre taper were applied.

Porphyrin-Embedded Silicate Materials for Detection of Hydrocarbon Solvents

DTIC Science & Technology

2011-01-14

Sensors 2011, 11, 886-904; doi:10.3390/s110100886 sensors ISSN 1424-8220 www.mdpi.com/journal/ sensors Article Porphyrin-Embedded Silicate...Prescribed by ANSI Std Z39-18 Sensors 2011, 11 887 1. Introduction Mesoporous silicates have been widely described in sensing...absorption spectroscopy, quartz crystal microbalance ( QCM ), and FTIR have been utilized for aromatic hydrocarbon sensing applications based on these

IFLA Section of Libraries for the Blind. Expert Meeting, 1984. Papers.

ERIC Educational Resources Information Center

International Federation of Library Associations, The Hague (Netherlands).

Papers on library services and developments in reading materials for the blind, which were presented at the 1984 Expert Meeting of the IFLA Section of Libraries for the Blind include: (1) "Teaching Map Concepts to the Blind" (R. B. Horsfall and B. Cox, Canada); (2) "Optical Character Recognition 'Reading' for Computerized Braille Production"…

Meeting the Needs of Able Learners through Flexible Pacing. ERIC Digest #464.

ERIC Educational Resources Information Center

ERIC Clearinghouse on Handicapped and Gifted Children, Reston, VA.

This information sheet, based on "Flexible Pacing for Able Learners" by Neil Daniel and June Cox, defines flexible pacing as any program in which students are taught material that is appropriately challenging for their ability and allows them to move forward in the curriculum as they master content and skill. The document outlines…

Fiber optic temperature sensor

NASA Technical Reports Server (NTRS)

Quick, William H. (Inventor); August, Rudolf R. (Inventor); James, Kenneth A. (Inventor); Strahan, Jr., Virgil H. (Inventor); Nichols, Donald K. (Inventor)

1980-01-01

An inexpensive, lightweight fiber optic micro-sensor that is suitable for applications which may require remote temperature sensing. The disclosed temperature sensor includes a phosphor material that, after receiving incident light stimulation, is adapted to emit phosphorescent radiation output signals, the amplitude decay rate and wavelength of which are functions of the sensed temperature.

46 CFR 153.565 - Special requirement for temperature sensors.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 5 2011-10-01 2011-10-01 false Special requirement for temperature sensors. 153.565... CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Special Requirements § 153.565 Special requirement for temperature sensors. If a cargo listed in...

46 CFR 153.565 - Special requirement for temperature sensors.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Special requirement for temperature sensors. 153.565... CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Special Requirements § 153.565 Special requirement for temperature sensors. If a cargo listed in...

46 CFR 153.440 - Cargo temperature sensors.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 5 2011-10-01 2011-10-01 false Cargo temperature sensors. 153.440 Section 153.440... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Temperature Control Systems § 153.440 Cargo temperature sensors. (a) Except as prescribed in paragraph (c) of...

46 CFR 153.440 - Cargo temperature sensors.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Cargo temperature sensors. 153.440 Section 153.440... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Temperature Control Systems § 153.440 Cargo temperature sensors. (a) Except as prescribed in paragraph (c) of...

Effect of temperature on the spectrum of fiber Bragg grating sensors embedded in polymer composite

NASA Astrophysics Data System (ADS)

Anoshkin, A. N.; Shipunov, G. S.; Voronkov, A. A.; Shardakov, I. N.

2017-12-01

This work presents the experimental results on the effect of temperature on the spectrum of fiber Bragg grating (FBG) sensors embedded in a polymer composite material manufactured by the prepreg method. The tests are carried out for flat bar specimens made of fiberglass with five embedded FBG sensors. For measuring the reflected wave power, the ASTRO X322 Interrogator is used. It is shown that embedding leads to the occurrence of an additional power peak and decreases the reflection spectrum signal by 10-12 dB. This is due to the effect of transverse compression force and the anisotropic character of the thermal expansion coefficient of the material. In heating, the reflected spectrum is close to the initial state of the material, but it has a less power.

The influence of cyclooxygenase-1 expression on the efficacy of cyclooxygenase-2 inhibition in head and neck squamous cell carcinoma cell lines.

PubMed

Park, Seok-Woo; Kim, Hyo-Sun; Choi, Myung-Sun; Kim, Ji-Eun; Jeong, Woo-Jin; Heo, Dae-Seog; Sung, Myung-Whun

2011-06-01

We have previously observed that cyclooxygenase-2 (COX-2) inhibition blocked the production of vascular endothelial growth factor (VEGF) in some head and neck squamous cell carcinoma (HNSCC) cells. However, as some HNSCC cells showed little response to COX-2 inhibition, although they highly expressed COX-2 and prostaglandin E2, we set out to elucidate what made this difference between them and focused on the possibility of the differential expression of COX-1. In western blotting, we found that COX-1 was expressed in SNU-1041 and SNU-1066, but not in SNU-1076 and PCI-50. Only in those cell lines without expression of COX-1 was VEGF production blocked meaningfully by small interfering RNA of COX-2. However, by cotreating with small interfering RNAs of COX-2 and COX-1, VEGF synthesis and prostaglandin E2 were inhibited in SNU-1041 and SNU-1066, similarly in SNU-1076 and PCI-50 with high expression of only COX-2. We also found that there was no difference in the pattern of prostaglandin synthesis between COX-2 and COX-1 through enzyme-linked immunosorbent assay for various prostaglandins. Our study suggests that, as COX-1 and COX-2 express and affect VEGF synthesis in HNSCC cells, we should check COX-1 expression in investigations on cancer treatment by inhibiting COX-2-induced prostaglandins.

The roles of the cyclo-oxygenases types one and two in prostaglandin synthesis in human fetal membranes at term.

PubMed

Sawdy, R J; Slater, D M; Dennes, W J; Sullivan, M H; Bennett, P R

2000-01-01

The aim of this study was to determine the relative contributions of cyclo-oxygenase (COX) types 1 and 2 to prostaglandin synthesis at term. Fetal membranes were collected from 6 pregnancies after elective caesarean section at term, prior to labour. The presence of COX-1 and COX-2 protein was determined using Western analysis. The relative contributions of the two isoforms of COX to prostaglandin synthesis were determined by incubation of fetal membrane discs with either a COX-2 selective inhibitor, SC236, or a COX-1 selective inhibitor, SC560, and measurement of prostaglandin release during 24 h using enzyme-linked immuno-sorbent assay (ELISA). Both COX-1 and COX-2 protein were demonstrated in amnion and chorion-decidua. The COX-2 selective inhibitor, SC-236, significantly reduced prostaglandin synthesis, both in its COX-2 specific and higher, non-specific concentration ranges. The COX-1 selective inhibitor, SC-560, had no effect upon prostaglandin synthesis in its COX-1 specific concentration range, but did significantly reduce prostaglandin synthesis at higher, non-selective concentrations. Fetal membranes contain both COX-1 and COX-2 at term, but only COX-2 contributes towards prostaglandin synthesis. COX-2 selective NSAI drugs will be as effective as non-selective agents in inhibition of fetal membrane prostaglandin synthesis and may represent a new strategy for tocolysis. Copyright 2000 Harcourt Publishers Ltd.

Fiber optic and laser sensors IX; Proceedings of the Meeting, Boston, MA, Sept. 3-5, 1991

NASA Technical Reports Server (NTRS)

Depaula, Ramon P. (Editor); Udd, Eric (Editor)

1991-01-01

The present volume on fiber-optic and laser sensors discusses industrial applications of fiber-optic sensors, fiber-optic temperature sensors, fiber-optic current sensors, fiber-optic pressure/displacement/vibration sensors, and generic fiber-optic systems. Attention is given to a fiber-sensor design for turbine engines, fiber-optic remote Fourier transform IR spectroscopy, near-IR fiber-optic temperature sensors, and an intensity-type fiber-optic electric current sensor. Topics addressed include fiber-optic magnetic field sensors based on the Faraday effect in new materials, diaphragm size and sensitivity for fiber-optic pressure sensors, a microbend pressure sensor for high-temperature environments, and linear position sensing by light exchange between two lossy waveguides. Also discussed are two-mode elliptical-core fiber sensors for measurement of strain and temperature, a fiber-optic interferometric X-ray dosimeter, fiber-optic interferometric sensors using multimode fibers, and optical fiber sensing of corona discharges.

Embedded Sensors for Measuring Surface Regression

NASA Technical Reports Server (NTRS)

Gramer, Daniel J.; Taagen, Thomas J.; Vermaak, Anton G.

2006-01-01

The development and evaluation of new hybrid and solid rocket motors requires accurate characterization of the propellant surface regression as a function of key operational parameters. These characteristics establish the propellant flow rate and are prime design drivers affecting the propulsion system geometry, size, and overall performance. There is a similar need for the development of advanced ablative materials, and the use of conventional ablatives exposed to new operational environments. The Miniature Surface Regression Sensor (MSRS) was developed to serve these applications. It is designed to be cast or embedded in the material of interest and regresses along with it. During this process, the resistance of the sensor is related to its instantaneous length, allowing the real-time thickness of the host material to be established. The time derivative of this data reveals the instantaneous surface regression rate. The MSRS could also be adapted to perform similar measurements for a variety of other host materials when it is desired to monitor thicknesses and/or regression rate for purposes of safety, operational control, or research. For example, the sensor could be used to monitor the thicknesses of brake linings or racecar tires and indicate when they need to be replaced. At the time of this reporting, over 200 of these sensors have been installed into a variety of host materials. An MSRS can be made in either of two configurations, denoted ladder and continuous (see Figure 1). A ladder MSRS includes two highly electrically conductive legs, across which narrow strips of electrically resistive material are placed at small increments of length. These strips resemble the rungs of a ladder and are electrically equivalent to many tiny resistors connected in parallel. A substrate material provides structural support for the legs and rungs. The instantaneous sensor resistance is read by an external signal conditioner via wires attached to the conductive legs on the non-eroding end of the sensor. The sensor signal can be transmitted from inside a high-pressure chamber to the ambient environment, using commercially available feedthrough connectors. Miniaturized internal recorders or wireless data transmission could also potentially be employed to eliminate the need for producing penetrations in the chamber case. The rungs are designed so that as each successive rung is eroded away, the resistance changes by an amount that yields a readily measurable signal larger than the background noise. (In addition, signal-conditioning techniques are used in processing the resistance readings to mitigate the effect of noise.) Hence, each discrete change of resistance serves to indicate the arrival of the regressing host material front at the known depth of the affected resistor rung. The average rate of regression between two adjacent resistors can be calculated simply as the distance between the resistors divided by the time interval between their resistance jumps. Advanced data reduction techniques have also been developed to establish the instantaneous surface position and regression rate when the regressing front is between rungs.

Vibration analysis of a new polymer quartz piezoelectric crystal sensor for detecting characteristic materials of volatility liquid

NASA Astrophysics Data System (ADS)

Gu, Yu; Li, Qiang; Xu, Bao-Jun; Zhao, Zhe

2014-01-01

We present a new polymer quartz piezoelectric crystal sensor that takes a quartz piezoelectric crystal as the basal material and a nanometer nonmetallic polymer thin film as the surface coating based on the principle of quartz crystal microbalance (QCM). The new sensor can be used to detect the characteristic materials of a volatile liquid. A mechanical model of the new sensor was built, whose structure was a thin circle plate composing of polytef/quartz piezoelectric/polytef. The mechanical model had a diameter of 8 mm and a thickness of 170 μm. The vibration state of the model was simulated by software ANSYS after the physical parameters and the boundary condition of the new sensor were set. According to the results of experiments, we set up a frequency range from 9.995850 MHz to 9.997225 MHz, 17 kinds of frequencies and modes of vibration were obtained within this range. We found a special frequency fsp of 9.996358 MHz. When the resonant frequency of the new sensor's mechanical model reached the special frequency, a special phenomenon occurred. In this case, the amplitude of the center point O on the mechanical model reached the maximum value. At the same time, the minimum absolute difference between the simulated frequency based on the ANSYS software and the experimental measured stable frequency was reached. The research showed that the design of the new polymer quartz piezoelectric crystal sensor perfectly conforms to the principle of QCM. A special frequency value fsp was found and subsequently became one of the most important parameters in the new sensor design.

Fiber-Optic Sensor And Smart Structures Research At Florida Institute Of Technology

NASA Astrophysics Data System (ADS)

Grossman, Barry G.; Alavie, A. Tino; Ham, Fredric M.; Franke, Jorge E.; Thursby, Michael H.

1990-02-01

This paper discusses the fundamental issues being investigated by Florida Institute of Technology (F.I.T.) to implement the technology of smart structural systems for DoD, NASA, and commercial applications. Embedded sensors and actuators controlled by processors can provide a modification of the mechanical characteristics of composite structures to produce smart structures1-3. Recent advances in material science have spurred the development and use of composite materials in a wide range of applications from rotocraft blades and advanced tactical fighter aircraft to undersea and aerospace structures. Along with the advantages of an increased strength-to-weight ratio, the use of these materials has raised a number of questions related to understanding their failure mechanisms. Also, being able to predict structural failures far enough in advance to prevent them and to provide real-time structural health and damage monitoring has become a realistic possibility. Unfortunately, conventional sensors, actuators, and digital processors, although highly developed and well proven for other systems, may not be best suited for most smart structure applications. Our research has concentrated on few-mode and polarimetric single-fiber strain sensors4-7 and optically activated shape memory alloy (SMA) actuators controlled by artificial neural processors. We have constructed and characterized both few-mode and polarimetric sensors for a variety of fiber types, including standard single-mode, high-birefringence polarization preserving, and low-birefringence polarization insensitive fibers. We have investigated signal processing techniques for these sensors and have demonstrated active phase tracking for the high- and low-birefringence polarimetric sensors through the incorporation into the system of an electrooptic modulator designed and fabricated at F.I.T.. We have also started the design and testing of neural network architectures for processing the sensor signal outputs to calculate strain magnitude and actuator control signals for simple structures.

Elastomer degradation sensor using a piezoelectric material

DOEpatents

Olness, Dolores U.; Hirschfeld, deceased, Tomas B.

1990-01-01

A method and apparatus for monitoring the degradation of elastomeric materials is provided. Piezoelectric oscillators are placed in contact with the elastomeric material so that a forced harmonic oscillator with damping is formed. The piezoelectric material is connected to an oscillator circuit,. A parameter such as the resonant frequency, amplitude or Q value of the oscillating system is related to the elasticity of the elastomeric material. Degradation of the elastomeric material causes changes in its elasticity which, in turn, causes the resonant frequency, amplitude or Q of the oscillator to change. These changes are monitored with a peak height monitor, frequency counter, Q-meter, spectrum analyzer, or other measurement circuit. Elasticity of elastomers can be monitored in situ, using miniaturized sensors.

Cell-type-specific roles for COX-2 in UVB-induced skin cancer

PubMed Central

Herschman, Harvey

2014-01-01

In human tumors, and in mouse models, cyclooxygenase-2 (COX-2) levels are frequently correlated with tumor development/burden. In addition to intrinsic tumor cell expression, COX-2 is often present in fibroblasts, myofibroblasts and endothelial cells of the tumor microenvironment, and in infiltrating immune cells. Intrinsic cancer cell COX-2 expression is postulated as only one of many sources for prostanoids required for tumor promotion/progression. Although both COX-2 inhibition and global Cox-2 gene deletion ameliorate ultraviolet B (UVB)-induced SKH-1 mouse skin tumorigenesis, neither manipulation can elucidate the cell type(s) in which COX-2 expression is required for tumorigenesis; both eliminate COX-2 activity in all cells. To address this question, we created Cox-2 flox/flox mice, in which the Cox-2 gene can be eliminated in a cell-type-specific fashion by targeted Cre recombinase expression. Cox-2 deletion in skin epithelial cells of SKH-1 Cox-2 flox/flox;K14Cre + mice resulted, following UVB irradiation, in reduced skin hyperplasia and increased apoptosis. Targeted epithelial cell Cox-2 deletion also resulted in reduced tumor incidence, frequency, size and proliferation rate, altered tumor cell differentiation and reduced tumor vascularization. Moreover, Cox-2 flox/flox;K14Cre + papillomas did not progress to squamous cell carcinomas. In contrast, Cox-2 deletion in SKH-1 Cox-2 flox/flox; LysMCre + myeloid cells had no effect on UVB tumor induction. We conclude that (i) intrinsic epithelial COX-2 activity plays a major role in UVB-induced skin cancer, (ii) macrophage/myeloid COX-2 plays no role in UVB-induced skin cancer and (iii) either there may be another COX-2-dependent prostanoid source(s) that drives UVB skin tumor induction or there may exist a COX-2-independent pathway(s) to UVB-induced skin cancer. PMID:24469308

Cell-type-specific roles for COX-2 in UVB-induced skin cancer.

PubMed

Jiao, Jing; Mikulec, Carol; Ishikawa, Tomo-o; Magyar, Clara; Dumlao, Darren S; Dennis, Edward A; Fischer, Susan M; Herschman, Harvey

2014-06-01

In human tumors, and in mouse models, cyclooxygenase-2 (COX-2) levels are frequently correlated with tumor development/burden. In addition to intrinsic tumor cell expression, COX-2 is often present in fibroblasts, myofibroblasts and endothelial cells of the tumor microenvironment, and in infiltrating immune cells. Intrinsic cancer cell COX-2 expression is postulated as only one of many sources for prostanoids required for tumor promotion/progression. Although both COX-2 inhibition and global Cox-2 gene deletion ameliorate ultraviolet B (UVB)-induced SKH-1 mouse skin tumorigenesis, neither manipulation can elucidate the cell type(s) in which COX-2 expression is required for tumorigenesis; both eliminate COX-2 activity in all cells. To address this question, we created Cox-2(flox/flox) mice, in which the Cox-2 gene can be eliminated in a cell-type-specific fashion by targeted Cre recombinase expression. Cox-2 deletion in skin epithelial cells of SKH-1 Cox-2(flox/flox);K14Cre(+) mice resulted, following UVB irradiation, in reduced skin hyperplasia and increased apoptosis. Targeted epithelial cell Cox-2 deletion also resulted in reduced tumor incidence, frequency, size and proliferation rate, altered tumor cell differentiation and reduced tumor vascularization. Moreover, Cox-2(flox/flox);K14Cre(+) papillomas did not progress to squamous cell carcinomas. In contrast, Cox-2 deletion in SKH-1 Cox-2(flox/flox); LysMCre(+) myeloid cells had no effect on UVB tumor induction. We conclude that (i) intrinsic epithelial COX-2 activity plays a major role in UVB-induced skin cancer, (ii) macrophage/myeloid COX-2 plays no role in UVB-induced skin cancer and (iii) either there may be another COX-2-dependent prostanoid source(s) that drives UVB skin tumor induction or there may exist a COX-2-independent pathway(s) to UVB-induced skin cancer. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Towards sensor array materials: can failure be delayed?

PubMed Central

Mekid, Samir; Saheb, Nouari; Khan, Shafique M A; Qureshi, Khurram K

2015-01-01

Further to prior development in enhancing structural health using smart materials, an innovative class of materials characterized by the ability to feel senses like humans, i.e. ‘nervous materials’, is discussed. Designed at all scales, these materials will enhance personnel and public safety, and secure greater reliability of products. Materials may fail suddenly, but any system wishes that failure is known in good time and delayed until safe conditions are reached. Nervous materials are expected to be the solution to this statement. This new class of materials is based on the novel concept of materials capable of feeling multiple structural and external stimuli, e.g. stress, force, pressure and temperature, while feeding information back to a controller for appropriate real-time action. The strain–stress state is developed in real time with the identified and characterized source of stimulus, with optimized time response to retrieve initial specified conditions, e.g. shape and strength. Sensors are volumetrically embedded and distributed, emulating the human nervous system. Immediate applications are in aircraft, cars, nuclear energy and robotics. Such materials will reduce maintenance costs, detect initial failures and delay them with self-healing. This article reviews the common aspects and challenges surrounding this new class of materials with types of sensors to be embedded seamlessly or inherently, including appropriate embedding manufacturing techniques with modeling and simulation methods. PMID:27877794

Towards sensor array materials: can failure be delayed?

NASA Astrophysics Data System (ADS)

Mekid, Samir; Saheb, Nouari; Khan, Shafique M. A.; Qureshi, Khurram K.

2015-06-01

Further to prior development in enhancing structural health using smart materials, an innovative class of materials characterized by the ability to feel senses like humans, i.e. ‘nervous materials’, is discussed. Designed at all scales, these materials will enhance personnel and public safety, and secure greater reliability of products. Materials may fail suddenly, but any system wishes that failure is known in good time and delayed until safe conditions are reached. Nervous materials are expected to be the solution to this statement. This new class of materials is based on the novel concept of materials capable of feeling multiple structural and external stimuli, e.g. stress, force, pressure and temperature, while feeding information back to a controller for appropriate real-time action. The strain-stress state is developed in real time with the identified and characterized source of stimulus, with optimized time response to retrieve initial specified conditions, e.g. shape and strength. Sensors are volumetrically embedded and distributed, emulating the human nervous system. Immediate applications are in aircraft, cars, nuclear energy and robotics. Such materials will reduce maintenance costs, detect initial failures and delay them with self-healing. This article reviews the common aspects and challenges surrounding this new class of materials with types of sensors to be embedded seamlessly or inherently, including appropriate embedding manufacturing techniques with modeling and simulation methods.

Differential cyclooxygenase-2 expression in squamous cell carcinoma and adenocarcinoma of the uterine cervix.

PubMed

Kim, Yong Bae; Kim, Gwi Eon; Pyo, Hong Ryull; Cho, Nam Hoon; Keum, Ki Chang; Lee, Chang Geol; Seong, Jinsil; Suh, Chang Ok; Park, Tchan Kyu

2004-11-01

To determine the differential expression of cyclooxygenase-2 (COX-2) in patients with squamous cell carcinoma (SCC) and adenocarcinoma (ADC) of the uterine cervix and the prognostic significance of COX-2 expression in these histologic types. A total of 105 International Federation of Gynecology and Obstetrics Stage IIB uterine cervical cancer patients were screened for COX-2 expression immunohistochemically. COX-2 expression was determined in invasive cervical SCC (n = 84) and invasive cervical ADC (n = 21). To determine the clinical significance of COX-2 expression by histologic type, the patients were arbitrarily divided into four groups: SCC/COX-2 negative (n = 64); SCC/COX-2 positive (n = 20); ADC/COX-2 negative (n = 9); and ADC/COX-2 positive (n = 12). The clinical response to treatment, patterns of treatment failure, and survival data by COX-2 expression were compared for these two major histologic types. Univariate and multivariate analyses were performed to identify the prognostic factors influencing survival. Immunohistochemical examination showed that COX-2 expression was more frequently observed in ADC than in SCC (57% vs. 24%, p = 0.007). Moreover, COX-2 expression was an important predictor of treatment response, irrespective of the histologic type. All COX-2-negative patients achieved complete remission after initial treatment; 17% of SCC patients and 33% of ADC patients with COX-2 expression did not have complete remission after the initial treatment. The incidence of local failure for those with COX-2 expression was significantly greater than for COX-2-negative patients, regardless of histologic type. With a minimal follow-up of 60 months, the overall 5-year actuarial survival rate for SCC and ADC patients was 79% and 62%, respectively (p = 0.05). The 5-year disease-free survival rate for SCC and ADC patients was 73% and 56%, respectively (p = 0.13). Irrespective of the pathologic type, COX-2-positive patients had an unfavorable prognosis. The overall 5-year actuarial survival rate was 57% for COX-2-positive patients and 83% for COX-2-negative patients (p = 0.001). When patients were stratified into the four groups according to histologic type and COX-2 expression status, ADC/COX-2-positive patients had the worst prognosis, with an overall 5-year actuarial survival rate of 49% compared with 78% for ADC/COX-2-negative patients, 62% for SCC/COX-2-positive, and 84% for SCC/COX-2-negative patients (p = 0.007, log-rank test). Irrespective of histologic type, COX-2 expression was an independent prognostic factor by univariate and multivariate analyses. In uterine cervical cancer, COX-2 was expressed in a greater proportion of ADC patients than SCC patients. COX-2 expression was also identified as a major determiner of a poor response to treatment and of an unfavorable prognosis, irrespective of the histologic type, reflecting the importance of the COX-2 protein in the acquisition of biologic aggressiveness and more malignant phenotype or increased resistance to the standard chemotherapy and radiotherapy in both histologic types. Given these observations, we believe that that ADC/COX-2-positive patients might be appropriate candidates for future trials of selective COX-2 inhibitor adjunctive therapy.

Flexible, Stretchable Sensors for Wearable Health Monitoring: Sensing Mechanisms, Materials, Fabrication Strategies and Features

PubMed Central

Liu, Yan; Wang, Hai; Zhao, Wei; Qin, Hongbo; Xie, Yongqiang

2018-01-01

Wearable health monitoring systems have gained considerable interest in recent years owing to their tremendous promise for personal portable health watching and remote medical practices. The sensors with excellent flexibility and stretchability are crucial components that can provide health monitoring systems with the capability of continuously tracking physiological signals of human body without conspicuous uncomfortableness and invasiveness. The signals acquired by these sensors, such as body motion, heart rate, breath, skin temperature and metabolism parameter, are closely associated with personal health conditions. This review attempts to summarize the recent progress in flexible and stretchable sensors, concerning the detected health indicators, sensing mechanisms, functional materials, fabrication strategies, basic and desired features. The potential challenges and future perspectives of wearable health monitoring system are also briefly discussed. PMID:29470408

Flexible, Stretchable Sensors for Wearable Health Monitoring: Sensing Mechanisms, Materials, Fabrication Strategies and Features.

PubMed

Liu, Yan; Wang, Hai; Zhao, Wei; Zhang, Min; Qin, Hongbo; Xie, Yongqiang

2018-02-22

Wearable health monitoring systems have gained considerable interest in recent years owing to their tremendous promise for personal portable health watching and remote medical practices. The sensors with excellent flexibility and stretchability are crucial components that can provide health monitoring systems with the capability of continuously tracking physiological signals of human body without conspicuous uncomfortableness and invasiveness. The signals acquired by these sensors, such as body motion, heart rate, breath, skin temperature and metabolism parameter, are closely associated with personal health conditions. This review attempts to summarize the recent progress in flexible and stretchable sensors, concerning the detected health indicators, sensing mechanisms, functional materials, fabrication strategies, basic and desired features. The potential challenges and future perspectives of wearable health monitoring system are also briefly discussed.

Capacitive proximity sensor

DOEpatents

Kronberg, J.W.

1994-05-31

A proximity sensor based on a closed field circuit is disclosed. The circuit comprises a ring oscillator using a symmetrical array of plates that creates an oscillating displacement current. The displacement current varies as a function of the proximity of objects to the plate array. Preferably the plates are in the form of a group of three pair of symmetric plates having a common center, arranged in a hexagonal pattern with opposing plates linked as a pair. The sensor produces logic level pulses suitable for interfacing with a computer or process controller. The proximity sensor can be incorporated into a load cell, a differential pressure gauge, or a device for measuring the consistency of a characteristic of a material where a variation in the consistency causes the dielectric constant of the material to change. 14 figs.

Tests of UFXC32k chip with CdTe pixel detector

NASA Astrophysics Data System (ADS)

Maj, P.; Taguchi, T.; Nakaye, Y.

2018-02-01

The paper presents the performance of the UFXC32K—a hybrid pixel detector readout chip working with CdTe detectors. The UFXC32K has a pixel pitch of 75 μm and can cope with both input signal polarities. This functionality allows operating with widely used silicon sensors collecting holes and CdTe sensors collecting electrons. This article describes the chip focusing on solving the issues connected to high-Z sensor material, namely high leakage currents, slow charge collection time and thick material resulting in increased charge-sharring effects. The measurements were conducted with higher X-ray energies including 17.4 keV from molybdenum. Conclusions drawn inside the paper show the UFXC32K's usability for CdTe sensors in high X-ray energy applications.

Review: Semiconductor Piezoresistance for Microsystems.

PubMed

Barlian, A Alvin; Park, Woo-Tae; Mallon, Joseph R; Rastegar, Ali J; Pruitt, Beth L

2009-01-01

Piezoresistive sensors are among the earliest micromachined silicon devices. The need for smaller, less expensive, higher performance sensors helped drive early micromachining technology, a precursor to microsystems or microelectromechanical systems (MEMS). The effect of stress on doped silicon and germanium has been known since the work of Smith at Bell Laboratories in 1954. Since then, researchers have extensively reported on microscale, piezoresistive strain gauges, pressure sensors, accelerometers, and cantilever force/displacement sensors, including many commercially successful devices. In this paper, we review the history of piezoresistance, its physics and related fabrication techniques. We also discuss electrical noise in piezoresistors, device examples and design considerations, and alternative materials. This paper provides a comprehensive overview of integrated piezoresistor technology with an introduction to the physics of piezoresistivity, process and material selection and design guidance useful to researchers and device engineers.

Platelet cyclooxygenase expression in normal dogs.

PubMed

Thomason, J; Lunsford, K; Mullins, K; Stokes, J; Pinchuk, L; Wills, R; McLaughlin, R; Langston, C; Pruett, S; Mackin, A

2011-01-01

Human platelets express both cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2). Variation in COX-2 expression could be a mechanism for variable response to aspirin. The hypotheses were that circulating canine platelets express COX-1 and COX-2, and that aspirin alters COX expression. The objective was to identify changes in platelet COX expression and in platelet function caused by aspirin administration to dogs. Eight female, intact hounds. A single population, repeated measures design was used to evaluate platelet COX-1 and COX-2 expression by flow cytometry before and after aspirin (10 mg/kg Q12h for 10 days). Platelet function was analyzed via PFA-100(®) (collagen/epinephrine), and urine 11-dehydro-thromboxane B(2) (11-dTXB(2)) was measured and normalized to urinary creatinine. Differences in COX expression, PFA-100(®) closure times, and urine 11-dTXB(2 ): creatinine ratio were analyzed before and after aspirin administration. Both COX-1 and COX-2 were expressed in canine platelets. COX-1 mean fluorescent intensity (MFI) increased in all dogs, by 250% (range 63-476%), while COX-2 expression did not change significantly (P = 0.124) after aspirin exposure, with large interindividual variation. PFA-100(®) closure times were prolonged and urine 11-dTXB(2) concentration decreased in all dogs after aspirin administration. Canine platelets express both COX isoforms. After aspirin exposure, COX-1 expression increased despite impairment of platelet function, while COX-2 expression varied markedly among dogs. Variability in platelet COX-2 expression should be explored as a potential mechanism for, or marker of, variable aspirin responsiveness. Copyright © 2011 by the American College of Veterinary Internal Medicine.

Role of cyclooxygenase isoforms in the altered excitatory motor pathways of human colon with diverticular disease.

PubMed

Fornai, M; Colucci, R; Antonioli, L; Ippolito, C; Segnani, C; Buccianti, P; Marioni, A; Chiarugi, M; Villanacci, V; Bassotti, G; Blandizzi, C; Bernardini, N

2014-08-01

The COX isoforms (COX-1, COX-2) regulate human gut motility, although their role under pathological conditions remains unclear. This study examines the effects of COX inhibitors on excitatory motility in colonic tissue from patients with diverticular disease (DD). Longitudinal muscle preparations, from patients with DD or uncomplicated cancer (controls), were set up in organ baths and connected to isotonic transducers. Indomethacin (COX-1/COX-2 inhibitor), SC-560 (COX-1 inhibitor) or DFU (COX-2 inhibitor) were assayed on electrically evoked, neurogenic, cholinergic and tachykininergic contractions, or carbachol- and substance P (SP)-induced myogenic contractions. Distribution and expression of COX isoforms in the neuromuscular compartment were assessed by RT-PCR, Western blot and immunohistochemical analysis. In control preparations, neurogenic cholinergic contractions were enhanced by COX inhibitors, whereas tachykininergic responses were blunted. Carbachol-evoked contractions were increased by indomethacin or SC-560, but not DFU, whereas all inhibitors reduced SP-induced motor responses. In preparations from DD patients, COX inhibitors did not affect electrically evoked cholinergic contractions. Both indomethacin and DFU, but not SC-560, decreased tachykininergic responses. COX inhibitors did not modify carbachol-evoked motor responses, whereas they counteracted SP-induced contractions. COX-1 expression was decreased in myenteric neurons, whereas COX-2 was enhanced in glial cells and smooth muscle. In control colon, COX-1 and COX-2 down-regulate cholinergic motility, whereas both isoforms enhance tachykininergic motor activity. In the presence of DD, there is a loss of modulation by both COX isoforms on the cholinergic system, whereas COX-2 displays an enhanced facilitatory control on tachykininergic contractile activity. © 2014 The British Pharmacological Society.

Role of cyclooxygenase isoforms in the altered excitatory motor pathways of human colon with diverticular disease

PubMed Central

Fornai, M; Colucci, R; Antonioli, L; Ippolito, C; Segnani, C; Buccianti, P; Marioni, A; Chiarugi, M; Villanacci, V; Bassotti, G; Blandizzi, C; Bernardini, N

2014-01-01

BACKGROUND AND PURPOSE The COX isoforms (COX-1, COX-2) regulate human gut motility, although their role under pathological conditions remains unclear. This study examines the effects of COX inhibitors on excitatory motility in colonic tissue from patients with diverticular disease (DD). EXPERIMENTAL APPROACH Longitudinal muscle preparations, from patients with DD or uncomplicated cancer (controls), were set up in organ baths and connected to isotonic transducers. Indomethacin (COX-1/COX-2 inhibitor), SC-560 (COX-1 inhibitor) or DFU (COX-2 inhibitor) were assayed on electrically evoked, neurogenic, cholinergic and tachykininergic contractions, or carbachol- and substance P (SP)-induced myogenic contractions. Distribution and expression of COX isoforms in the neuromuscular compartment were assessed by RT-PCR, Western blot and immunohistochemical analysis. KEY RESULTS In control preparations, neurogenic cholinergic contractions were enhanced by COX inhibitors, whereas tachykininergic responses were blunted. Carbachol-evoked contractions were increased by indomethacin or SC-560, but not DFU, whereas all inhibitors reduced SP-induced motor responses. In preparations from DD patients, COX inhibitors did not affect electrically evoked cholinergic contractions. Both indomethacin and DFU, but not SC-560, decreased tachykininergic responses. COX inhibitors did not modify carbachol-evoked motor responses, whereas they counteracted SP-induced contractions. COX-1 expression was decreased in myenteric neurons, whereas COX-2 was enhanced in glial cells and smooth muscle. CONCLUSIONS AND IMPLICATIONS In control colon, COX-1 and COX-2 down-regulate cholinergic motility, whereas both isoforms enhance tachykininergic motor activity. In the presence of DD, there is a loss of modulation by both COX isoforms on the cholinergic system, whereas COX-2 displays an enhanced facilitatory control on tachykininergic contractile activity. PMID:24758697

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.

Deposition Of Thin-Film Sensors On Glass-Fiber/Epoxy Models

NASA Technical Reports Server (NTRS)

Tran, Sang Q.

1995-01-01

Direct-deposition process devised for fabrication of thin-film sensors on three-dimensional, curved surfaces of models made of stainless steel covered with glass-fiber/epoxy-matrix composite material. Models used under cryogenic conditions, and sensors used to detect on-line transitions between laminar and turbulent flows in wind tunnel environments. Sensors fabricated by process used at temperatures from minus 300 degrees F to 175 degrees F.

Molecular sieve sensors for selective detection at the nanogram level

DOEpatents

Bein, Thomas; Brown, Kelly D.; Frye, Gregory C.; Brinker, Charles J.

1992-01-01

The invention relates to a selective chemical sensor for selective detection of chemical entities even at the nanogram level. The invention further relates to methods of using the sensor. The sensor comprises: (a) a piezoelectric substrate capable of detecting mass changes resulting from adsorption of material thereon; and (b) a coating applied to the substrate, which selectively sorbs chemical entities of a size smaller than a preselected magnitude.

The Capability of Fiber Bragg Grating Sensors to Measure Amputees' Trans-Tibial Stump/Socket Interface Pressures

PubMed Central

Al-Fakih, Ebrahim A.; Abu Osman, Noor Azuan; Eshraghi, Arezoo; Adikan, Faisal Rafiq Mahamd

2013-01-01

This study presents the first investigation into the capability of fiber Bragg grating (FBG) sensors to measure interface pressure between the stump and the prosthetic sockets of a trans-tibial amputee. FBG element(s) were recoated with and embedded in a thin layer of epoxy material to form a sensing pad, which was in turn embedded in a silicone polymer material to form a pressure sensor. The sensor was tested in real time by inserting a heavy-duty balloon into the socket and inflating it by using an air compressor. This test was conducted to examine the sensitivity and repeatability of the sensor when subjected to pressure from the stump of the trans-tibial amputee and to mimic the actual environment of the amputee's Patellar Tendon (PT) bar. The sensor exhibited a sensitivity of 127 pm/N and a maximum FSO hysteresis of around ∼0.09 in real-time operation. Very good reliability was achieved when the sensor was utilized for in situ measurements. This study may lead to smart FBG-based amputee stump/socket structures for pressure monitoring in amputee socket systems, which will result in better-designed prosthetic sockets that ensure improved patient satisfaction. PMID:23941909

Review on water quality sensors

NASA Astrophysics Data System (ADS)

Kruse, Peter

2018-05-01

Terrestrial life may be carbon-based, but most of its mass is made up of water. Access to clean water is essential to all aspects of maintaining life. Mainly due to human activity, the strain on the water resources of our planet has increased substantially, requiring action in water management and purification. Water quality sensors are needed in order to quantify the problem and verify the success of remedial actions. This review summarizes the most common chemical water quality parameters, and current developments in sensor technology available to monitor them. Particular emphasis is on technologies that lend themselves to reagent-free, low-maintenance, autonomous and continuous monitoring. Chemiresistors and other electrical sensors are discussed in particular detail, while mechanical, optical and electrochemical sensors also find mentioning. The focus here is on the physics of chemical signal transduction in sensor elements that are in direct contact with the analyte. All other sensing methods, and all other elements of sampling, sample pre-treatment as well as the collection, transmission and analysis of the data are not discussed here. Instead, the goal is to highlight the progress and remaining challenges in the development of sensor materials and designs for an audience of physicists and materials scientists.

Multivariable passive RFID vapor sensors: roll-to-roll fabrication on a flexible substrate.

PubMed

Potyrailo, Radislav A; Burns, Andrew; Surman, Cheryl; Lee, D J; McGinniss, Edward

2012-06-21

We demonstrate roll-to-roll (R2R) fabrication of highly selective, battery-free radio frequency identification (RFID) sensors on a flexible polyethylene terephthalate (PET) polymeric substrate. Selectivity of our developed RFID sensors is provided by measurements of their resonance impedance spectra, followed by the multivariate analysis of spectral features, and correlation of these spectral features to the concentrations of vapors of interest. The multivariate analysis of spectral features also provides the ability for the rejection of ambient interferences. As a demonstration of our R2R fabrication process, we employed polyetherurethane (PEUT) as a "classic" sensing material, extruded this sensing material as 25, 75, and 125-μm thick films, and thermally laminated the films onto RFID inlays, rapidly producing approximately 5000 vapor sensors. We further tested these RFID vapor sensors for their response selectivity toward several model vapors such as toluene, acetone, and ethanol as well as water vapor as an abundant interferent. Our RFID sensing concept features 16-bit resolution provided by the sensor reader, granting a highly desired independence from costly proprietary RFID memory chips with a low-resolution analog input. Future steps are being planned for field-testing of these sensors in numerous conditions.

Non-destructive evaluation of laminated composite plates using dielectrometry sensors

NASA Astrophysics Data System (ADS)

Nassr, Amr A.; El-Dakhakhni, Wael W.

2009-05-01

The use of composite materials in marine, aerospace and automotive applications is increasing; however, several kinds of damages of composite materials may influence its durability and future applications. In this paper, a methodology was presented for damage detection of laminated composite plates using dielectrometry sensors. The presence of damage in the laminated composite plate leads to changes in its dielectric characteristics, causing variation in the measured capacitance by the sensors. An analytical model was used to analyse the influence of different sensor parameters on the output signals and to optimize sensor design. Two-dimensional finite element (FE) simulations were performed to assess the validity of the analytical results and to evaluate other sensor design-related parameters. To experimentally verify the model, the dielectric permittivity of the composite plate was measured. In addition, a glass fibre reinforced polymer (GFRP) laminated plate containing pre-fabricated slots through its thickness to simulate delamination and water intrusion defects was inspected in a laboratory setting. Excellent agreements were found between the experimental capacitance response signals and those predicated from the FE simulations. This cost-effective technique can be used for rapid damage screening, regular scheduled inspection, or as a permanent sensor network within the composite system.

The capability of fiber Bragg grating sensors to measure amputees' trans-tibial stump/socket interface pressures.

PubMed

Al-Fakih, Ebrahim A; Osman, Noor Azuan Abu; Eshraghi, Arezoo; Adikan, Faisal Rafiq Mahamd

2013-08-12

This study presents the first investigation into the capability of fiber Bragg grating (FBG) sensors to measure interface pressure between the stump and the prosthetic sockets of a trans-tibial amputee. FBG element(s) were recoated with and embedded in a thin layer of epoxy material to form a sensing pad, which was in turn embedded in a silicone polymer material to form a pressure sensor. The sensor was tested in real time by inserting a heavy-duty balloon into the socket and inflating it by using an air compressor. This test was conducted to examine the sensitivity and repeatability of the sensor when subjected to pressure from the stump of the trans-tibial amputee and to mimic the actual environment of the amputee's Patellar Tendon (PT) bar. The sensor exhibited a sensitivity of 127 pm/N and a maximum FSO hysteresis of around ~0.09 in real-time operation. Very good reliability was achieved when the sensor was utilized for in situ measurements. This study may lead to smart FBG-based amputee stump/socket structures for pressure monitoring in amputee socket systems, which will result in better-designed prosthetic sockets that ensure improved patient satisfaction.

Error Analysis of Clay-Rock Water Content Estimation with Broadband High-Frequency Electromagnetic Sensors—Air Gap Effect

PubMed Central

Bore, Thierry; Wagner, Norman; Delepine Lesoille, Sylvie; Taillade, Frederic; Six, Gonzague; Daout, Franck; Placko, Dominique

2016-01-01

Broadband electromagnetic frequency or time domain sensor techniques present high potential for quantitative water content monitoring in porous media. Prior to in situ application, the impact of the relationship between the broadband electromagnetic properties of the porous material (clay-rock) and the water content on the frequency or time domain sensor response is required. For this purpose, dielectric properties of intact clay rock samples experimental determined in the frequency range from 1 MHz to 10 GHz were used as input data in 3-D numerical frequency domain finite element field calculations to model the one port broadband frequency or time domain transfer function for a three rods based sensor embedded in the clay-rock. The sensor response in terms of the reflection factor was analyzed in time domain with classical travel time analysis in combination with an empirical model according to Topp equation, as well as the theoretical Lichtenecker and Rother model (LRM) to estimate the volumetric water content. The mixture equation considering the appropriate porosity of the investigated material provide a practical and efficient approach for water content estimation based on classical travel time analysis with the onset-method. The inflection method is not recommended for water content estimation in electrical dispersive and absorptive material. Moreover, the results clearly indicate that effects due to coupling of the sensor to the material cannot be neglected. Coupling problems caused by an air gap lead to dramatic effects on water content estimation, even for submillimeter gaps. Thus, the quantitative determination of the in situ water content requires careful sensor installation in order to reach a perfect probe clay rock coupling. PMID:27096865

Acoustic Nondestructive Evaluation of Aircraft Paneling Using Piezoelectric Sensors

DTIC Science & Technology

2012-12-01

Electromagnetic Materials Team of the U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Clinical Trials Monitoring Branch, for...connected to this clip. This electrical connection ensures single-point grounding, which has been implemented to avoid electromagnetic interference...waveform of each sensor features an electromagnetic pick-up signature that is aligned with the transduced signal but phase shifted by 180. We know to

Germanium Requirements for National Defense,

DTIC Science & Technology

1991-07-01

work in this area involves development of hard exterior coating materials that will protect Ge windows but not adversely affect their optical...advanced electronic materials, is used in semiconductor devices, fiber optic systems, and infrared sensors for ships, aircraft, missiles, tanks and anti -tank...infrared sensors for ships, aircraft, missiles, tanks and anti -tank units. Because of its importance in these applications, germanium was added to the

High-temperature optical fiber sensors for characterization of advanced composite aerospace materials

NASA Astrophysics Data System (ADS)

Wavering, Thomas A.; Greene, Jonathan A.; Meller, Scott A.; Bailey, Timothy A.; Kozikowski, Carrie L.; Lenahan, Shannon M.; Murphy, Kent A.; Camden, Michael P.; Simmons, Larry W.

1999-01-01

Optical fiber sensors have numerous advantages over conventional sensing technologies. One such advantage is that optical fiber sensors can operate in high temperature environments. While most conventional electrical-based sensors do not operate reliably over 300 degrees C, fused silica based optical fiber sensors can survive up to 900 degrees C, and sapphire based optical fiber sensors can survive up to 2000 degrees C. Using both fused silica and sapphire technologies, we present result for high temperature strain, pressure, and temperature sensors using Extrinsic Fabry-Perot INterferometric-based and Bragg grating sensors. High temperature strain and temperature sensors were used to conduct fatigue testing of composite coupons at 600 degrees C. The results from these specific high temperature applications are presented along with future applications and directions for these sensors.

RadMAP: The Radiological Multi-sensor Analysis Platform

NASA Astrophysics Data System (ADS)

Bandstra, Mark S.; Aucott, Timothy J.; Brubaker, Erik; Chivers, Daniel H.; Cooper, Reynold J.; Curtis, Joseph C.; Davis, John R.; Joshi, Tenzing H.; Kua, John; Meyer, Ross; Negut, Victor; Quinlan, Michael; Quiter, Brian J.; Srinivasan, Shreyas; Zakhor, Avideh; Zhang, Richard; Vetter, Kai

2016-12-01

The variability of gamma-ray and neutron background during the operation of a mobile detector system greatly limits the ability of the system to detect weak radiological and nuclear threats. The natural radiation background measured by a mobile detector system is the result of many factors, including the radioactivity of nearby materials, the geometric configuration of those materials and the system, the presence of absorbing materials, and atmospheric conditions. Background variations tend to be highly non-Poissonian, making it difficult to set robust detection thresholds using knowledge of the mean background rate alone. The Radiological Multi-sensor Analysis Platform (RadMAP) system is designed to allow the systematic study of natural radiological background variations and to serve as a development platform for emerging concepts in mobile radiation detection and imaging. To do this, RadMAP has been used to acquire extensive, systematic background measurements and correlated contextual data that can be used to test algorithms and detector modalities at low false alarm rates. By combining gamma-ray and neutron detector systems with data from contextual sensors, the system enables the fusion of data from multiple sensors into novel data products. The data are curated in a common format that allows for rapid querying across all sensors, creating detailed multi-sensor datasets that are used to study correlations between radiological and contextual data, and develop and test novel techniques in mobile detection and imaging. In this paper we will describe the instruments that comprise the RadMAP system, the effort to curate and provide access to multi-sensor data, and some initial results on the fusion of contextual and radiological data.

Optical Sensors for Detection of Amino Acids.

PubMed

Pettiwala, Aafrin M; Singh, Prabhat K

2017-11-06

Amino acids are crucially involved in a myriad of biological processes. Any aberrant changes in physiological level of amino acids often manifest in common metabolic disorders, serious neurological conditions and cardiovascular diseases. Thus, devising methods for detection of trace amounts of amino acids becomes highly elemental to their efficient clinical diagnosis. Recently, the domain of developing optical sensors for detection of amino acids has witnessed significant activity which is the focus of the current review article. We undertook a detailed search of the peer-reviewed literature that primarily deals with optical sensors for amino acids and focuses on the use of different type of materials as a sensing platform. Ninety-five papers have been included in the review, majority of which deals with optical sensors. We attempt to systematically classify these contributions based on applications of various chemical and biological scaffolds such as polymers, supramolecular assemblies, nanoparticles, DNA, heparin etc. for the sensing of amino acids. This review identifies that supramolecular assemblies and nanomaterial continue to be commonly used materials to devise sensors for amino acids followed by surfactant assemblies. The broad implications of amino acids in human health and diagnosis have stirred a lot of interest to develop optimized optical detection systems for amino acids in recent years, using different materials based on chemical and biological scaffolds. We have also attempted to highlight the merits and demerits of some of the noteworthy sensor systems to instigate further efforts for constructing amino acids sensor based on unconventional concepts. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Functionalized MEMS Sensors for Capacity-Based Residual Life Indicators

DTIC Science & Technology

2015-03-09

The new measurement cell has been built and evaluated. Sensors have been coated with MOF CuBTC films by Dr. M. Allendorf at Sandia. The sensors...Thickness of Silicon Piezoresistors (nm) In MOF Ag Figure 17: Plot of delta R as a function of chemically induced strain for different materials on back

Single-Input and Multiple-Output Surface Acoustic Wave Sensing for Damage Quantification in Piezoelectric Sensors.

PubMed

Pamwani, Lavish; Habib, Anowarul; Melandsø, Frank; Ahluwalia, Balpreet Singh; Shelke, Amit

2018-06-22

The main aim of the paper is damage detection at the microscale in the anisotropic piezoelectric sensors using surface acoustic waves (SAWs). A novel technique based on the single input and multiple output of Rayleigh waves is proposed to detect the microscale cracks/flaws in the sensor. A convex-shaped interdigital transducer is fabricated for excitation of divergent SAWs in the sensor. An angularly shaped interdigital transducer (IDT) is fabricated at 0 degrees and ±20 degrees for sensing the convex shape evolution of SAWs. A precalibrated damage was introduced in the piezoelectric sensor material using a micro-indenter in the direction perpendicular to the pointing direction of the SAW. Damage detection algorithms based on empirical mode decomposition (EMD) and principal component analysis (PCA) are implemented to quantify the evolution of damage in piezoelectric sensor material. The evolution of the damage was quantified using a proposed condition indicator (CI) based on normalized Euclidean norm of the change in principal angles, corresponding to pristine and damaged states. The CI indicator provides a robust and accurate metric for detection and quantification of damage.

A fiber optic temperature sensor based on the combination of epoxy and glass particles with different thermo-optic coefficients

NASA Astrophysics Data System (ADS)

Wildner, Wolfgang; Drummer, Dietmar

2016-12-01

This paper describes the development and function of an optical fiber temperature sensor made out of a compound of epoxy and optical glass particles. Because of the different thermo-optic coefficients of these materials, this compound exhibits a strong wavelength and temperature dependent optical transmission, and it therefore can be employed for fiber optic temperature measurements. The temperature at the sensor, which is integrated into a polymer optical fiber (POF), is evaluated by the ratio of the transmitted intensity of two different light-emitting diodes (LED) with a wavelength of 460 nm and 650 nm. The material characterization and influences of different sensor lengths and two particle sizes on the measurement result are discussed. The temperature dependency of the transmission increases with smaller particles and with increasing sensor length. With glass particles with a diameter of 43 μm and a sensor length of 9.8 mm, the intensity ratio of the two LEDs decreases by 60% within a temperature change from 10°C to 40°C.

New fluorescent pH sensors based on covalently linkable PET rhodamines

PubMed Central

Aigner, Daniel; Borisov, Sergey M.; Orriach Fernández, Francisco J.; Fernández Sánchez, Jorge F.; Saf, Robert; Klimant, Ingo

2012-01-01

A new class of rhodamines for the application as indicator dyes in fluorescent pH sensors is presented. Their pH-sensitivity derives from photoinduced electron transfer between non-protonated amino groups and the excited chromophore which results in effective fluorescence quenching at increasing pH. The new indicator class carries a pentafluorophenyl group at the 9-position of the xanthene core where other rhodamines bear 2-carboxyphenyl substituents instead. The pentafluorophenyl group is used for covalent coupling to sensor matrices by “click” reaction with mercapto groups. Photophysical properties are similar to “classical” rhodamines carrying 2′-carboxy groups. pH sensors have been prepared with two different matrix materials, silica gel and poly(2-hydroxyethylmethacrylate). Both sensors show high luminescence brightness (absolute fluorescence quantum yield ΦF≈0.6) and high pH-sensitivity at pH 5–7 which makes them suitable for monitoring biotechnological samples. To underline practical applicability, a dually lifetime referenced sensor containing Cr(III)-doped Al2O3 as reference material is presented. PMID:22967541

Multi-field coupled sensing network for health monitoring of composite bolted joint

NASA Astrophysics Data System (ADS)

Wang, Yishou; Qing, Xinlin; Dong, Liang; Banerjee, Sourav

2016-04-01

Advanced fiber reinforced composite materials are becoming the main structural materials of next generation of aircraft because of their high strength and stiffness to weight ratios, and excellent designability. As key components of large composite structures, joints play important roles to ensure the integrity of the composite structures. However, it is very difficult to analyze the strength and failure modes of composite joints due to their complex nonlinear coupling factors. Therefore, there is a need to monitor, diagnose, evaluate and predict the structure state of composite joints. This paper proposes a multi-field coupled sensing network for health monitoring of composite bolted joints. Major work of this paper includes: 1) The concept of multifunctional sensor layer integrated with eddy current sensors, Rogowski coil and arrayed piezoelectric sensors; 2) Development of the process for integrating the eddy current sensor foil, Rogowski coil and piezoelectric sensor array in multifunctional sensor layer; 3) A new concept of smart composite joint with multifunctional sensing capability. The challenges for building such a structural state sensing system and some solutions to address the challenges are also discussed in the study.

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

Advances in Thin Film Sensor Technologies for Engine Applications

NASA Technical Reports Server (NTRS)

Lei, Jih-Fen; Martin, Lisa C.; Will, Herbert A.

1997-01-01

Advanced thin film sensor techniques that can provide accurate surface strain and temperature measurements are being developed at NASA Lewis Research Center. These sensors are needed to provide minimally intrusive characterization of advanced materials (such as ceramics and composites) and structures (such as components for Space Shuttle Main Engine, High Speed Civil Transport, Advanced Subsonic Transports and General Aviation Aircraft) in hostile, high-temperature environments and for validation of design codes. This paper presents two advanced thin film sensor technologies: strain gauges and thermocouples. These sensors are sputter deposited directly onto the test articles and are only a few micrometers thick; the surface of the test article is not structurally altered and there is minimal disturbance of the gas flow over the surface. The strain gauges are palladium-13% chromium based and the thermocouples are platinum-13% rhodium vs. platinum. The fabrication techniques of these thin film sensors in a class 1000 cleanroom at the NASA Lewis Research Center are described. Their demonstration on a variety of engine materials, including superalloys, ceramics and advanced ceramic matrix composites, in several hostile, high-temperature test environments are discussed.

Material for surface-enhanced Raman spectroscopy, and SER sensors and method for preparing same

NASA Technical Reports Server (NTRS)

Farquharson, Stuart (Inventor); Nelson, Chad (Inventor); Lee, Yuan-Hsiang (Inventor)

2003-01-01

Metal-doped sol-gel materials, suitable for use as sensors for surface-enhanced Raman spectroscopic analysis for trace chemical detection, are produced by effecting gelation and solvent removal of a doped sol-gel under mild temperature conditions. At least in certain instances reaction and drying will desirably be effected in an oxygen-starved environment. The metal of the sol-gel material functions, when irradiated, to produce a plasmon field for interaction with molecules of an analyte in contact therewith, increasing by orders of magnitude Raman photons that are generate by excitation radiation, and the method allows matching of the metal and metal particle size to a wavelength of light (or incident radiation, e.g., laser radiation) to generate surface plasmons. The porosity of the sol-gel material dramatically increases the surface area, and thereby the amount of metal exposed for analyte interaction. The sensors provided may be in the form of glass vials, fiber optics, multi-well micro-sample plates, etc., having surface coatings of the doped sol-gel material, to provide sampling systems for use in a Raman instrument.