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

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

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

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

Nanostructured Metal Oxide Gas Sensors, a Survey of Applications Carried out at SENSOR Lab, Brescia (Italy) in the Security and Food Quality Fields

PubMed Central

Ponzoni, Andrea; Comini, Elisabetta; Concina, Isabella; Ferroni, Matteo; Falasconi, Matteo; Gobbi, Emanuela; Sberveglieri, Veronica; Sberveglieri, Giorgio

2012-01-01

In this work we report on metal oxide (MOX) based gas sensors, presenting the work done at the SENSOR laboratory of the CNR-IDASC and University of Brescia, Italy since the 80s up to the latest results achieved in recent times. In particular we report the strategies followed at SENSOR during these 30 years to increase the performance of MOX sensors through the development of different preparation techniques, from Rheotaxial Growth Thermal Oxidation (RGTO) to nanowire technology to address sensitivity and stability, and the development of electronic nose systems and pattern recognition techniques to address selectivity. We will show the obtained achievement in the context of selected applications such as safety and security and food quality control. PMID:23235445

Detection and Monitoring of Toxic Chemical at Ultra Trace Level by Utilizing Doped Nanomaterial

PubMed Central

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

2014-01-01

Composite nanoparticles were synthesized by eco-friendly hydrothermal process and characterized by different spectroscopic techniques. All the spectroscopic techniques suggested the synthesis of well crystalline optically active composite nanoparticles with average diameter of ∼30 nm. The synthesized nanoparticles were applied for the development of chemical sensor which was fabricated by coating the nanoparticles on silver electrode for the recognition of phthalimide using simple I–V technique. The developed sensor exhibited high sensitivity (1.7361 µA.mM−1.cm−2), lower detection limit (8.0 µM) and long range of detection (77.0 µM to 0.38 M). Further the resistances of composite nanoparticles based sensor was found to be 2.7 MΩ which change from 2.7 to 1.7 with change in phthalimide concentration. The major advantages of the designed sensor over existing sensors are its simple technique, low cost, lower detection limit, high sensitivity and long range of detection. It can detect phthalimide even at trace level and sense over wide range of concentrations. Therefore the composite nanoparticals would be a better choice for the fabrication of phthalimide chemical sensor and would be time and cost substituted implement for environmental safety. PMID:25329666

A near-optimal low complexity sensor fusion technique for accurate indoor localization based on ultrasound time of arrival measurements from low-quality sensors

NASA Astrophysics Data System (ADS)

Mitilineos, Stelios A.; Argyreas, Nick D.; Thomopoulos, Stelios C. A.

2009-05-01

A fusion-based localization technique for location-based services in indoor environments is introduced herein, based on ultrasound time-of-arrival measurements from multiple off-the-shelf range estimating sensors which are used in a market-available localization system. In-situ field measurements results indicated that the respective off-the-shelf system was unable to estimate position in most of the cases, while the underlying sensors are of low-quality and yield highly inaccurate range and position estimates. An extensive analysis is performed and a model of the sensor-performance characteristics is established. A low-complexity but accurate sensor fusion and localization technique is then developed, which consists inof evaluating multiple sensor measurements and selecting the one that is considered most-accurate based on the underlying sensor model. Optimality, in the sense of a genie selecting the optimum sensor, is subsequently evaluated and compared to the proposed technique. The experimental results indicate that the proposed fusion method exhibits near-optimal performance and, albeit being theoretically suboptimal, it largely overcomes most flaws of the underlying single-sensor system resulting in a localization system of increased accuracy, robustness and availability.

Dynamic model inversion techniques for breath-by-breath measurement of carbon dioxide from low bandwidth sensors.

PubMed

Sivaramakrishnan, Shyam; Rajamani, Rajesh; Johnson, Bruce D

2009-01-01

Respiratory CO(2) measurement (capnography) is an important diagnosis tool that lacks inexpensive and wearable sensors. This paper develops techniques to enable use of inexpensive but slow CO(2) sensors for breath-by-breath tracking of CO(2) concentration. This is achieved by mathematically modeling the dynamic response and using model-inversion techniques to predict input CO(2) concentration from the slow-varying output. Experiments are designed to identify model-dynamics and extract relevant model-parameters for a solidstate room monitoring CO(2) sensor. A second-order model that accounts for flow through the sensor's filter and casing is found to be accurate in describing the sensor's slow response. The resulting estimate is compared with a standard-of-care respiratory CO(2) analyzer and shown to effectively track variation in breath-by-breath CO(2) concentration. This methodology is potentially useful for measuring fast-varying inputs to any slow sensor.

Magnetoresistive biosensors for quantitative proteomics

NASA Astrophysics Data System (ADS)

Zhou, Xiahan; Huang, Chih-Cheng; Hall, Drew A.

2017-08-01

Quantitative proteomics, as a developing method for study of proteins and identification of diseases, reveals more comprehensive and accurate information of an organism than traditional genomics. A variety of platforms, such as mass spectrometry, optical sensors, electrochemical sensors, magnetic sensors, etc., have been developed for detecting proteins quantitatively. The sandwich immunoassay is widely used as a labeled detection method due to its high specificity and flexibility allowing multiple different types of labels. While optical sensors use enzyme and fluorophore labels to detect proteins with high sensitivity, they often suffer from high background signal and challenges in miniaturization. Magnetic biosensors, including nuclear magnetic resonance sensors, oscillator-based sensors, Hall-effect sensors, and magnetoresistive sensors, use the specific binding events between magnetic nanoparticles (MNPs) and target proteins to measure the analyte concentration. Compared with other biosensing techniques, magnetic sensors take advantage of the intrinsic lack of magnetic signatures in biological samples to achieve high sensitivity and high specificity, and are compatible with semiconductor-based fabrication process to have low-cost and small-size for point-of-care (POC) applications. Although still in the development stage, magnetic biosensing is a promising technique for in-home testing and portable disease monitoring.

Recent Advances of MEMS Resonators for Lorentz Force Based Magnetic Field Sensors: Design, Applications and Challenges.

PubMed

Herrera-May, Agustín Leobardo; Soler-Balcazar, Juan Carlos; Vázquez-Leal, Héctor; Martínez-Castillo, Jaime; Vigueras-Zuñiga, Marco Osvaldo; Aguilera-Cortés, Luz Antonio

2016-08-24

Microelectromechanical systems (MEMS) resonators have allowed the development of magnetic field sensors with potential applications such as biomedicine, automotive industry, navigation systems, space satellites, telecommunications and non-destructive testing. We present a review of recent magnetic field sensors based on MEMS resonators, which operate with Lorentz force. These sensors have a compact structure, wide measurement range, low energy consumption, high sensitivity and suitable performance. The design methodology, simulation tools, damping sources, sensing techniques and future applications of magnetic field sensors are discussed. The design process is fundamental in achieving correct selection of the operation principle, sensing technique, materials, fabrication process and readout systems of the sensors. In addition, the description of the main sensing systems and challenges of the MEMS sensors are discussed. To develop the best devices, researches of their mechanical reliability, vacuum packaging, design optimization and temperature compensation circuits are needed. Future applications will require multifunctional sensors for monitoring several physical parameters (e.g., magnetic field, acceleration, angular ratio, humidity, temperature and gases).

Recent Advances of MEMS Resonators for Lorentz Force Based Magnetic Field Sensors: Design, Applications and Challenges

PubMed Central

Herrera-May, Agustín Leobardo; Soler-Balcazar, Juan Carlos; Vázquez-Leal, Héctor; Martínez-Castillo, Jaime; Vigueras-Zuñiga, Marco Osvaldo; Aguilera-Cortés, Luz Antonio

2016-01-01

Microelectromechanical systems (MEMS) resonators have allowed the development of magnetic field sensors with potential applications such as biomedicine, automotive industry, navigation systems, space satellites, telecommunications and non-destructive testing. We present a review of recent magnetic field sensors based on MEMS resonators, which operate with Lorentz force. These sensors have a compact structure, wide measurement range, low energy consumption, high sensitivity and suitable performance. The design methodology, simulation tools, damping sources, sensing techniques and future applications of magnetic field sensors are discussed. The design process is fundamental in achieving correct selection of the operation principle, sensing technique, materials, fabrication process and readout systems of the sensors. In addition, the description of the main sensing systems and challenges of the MEMS sensors are discussed. To develop the best devices, researches of their mechanical reliability, vacuum packaging, design optimization and temperature compensation circuits are needed. Future applications will require multifunctional sensors for monitoring several physical parameters (e.g., magnetic field, acceleration, angular ratio, humidity, temperature and gases). PMID:27563912

Turbine blade and vane heat flux sensor development, phase 1

NASA Technical Reports Server (NTRS)

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

1984-01-01

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

Turbine blade and vane heat flux sensor development, phase 1

NASA Astrophysics Data System (ADS)

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

1984-08-01

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

Close-range sensors for small unmanned bottom vehicles: update

NASA Astrophysics Data System (ADS)

Bernstein, Charles L.

2000-07-01

The Surf Zone Reconnaissance Project is developing sensors for small, autonomous, Underwater Bottom-crawling Vehicles. The objective is to enable small, crawling robots to autonomously detect and classify mines and obstacles on the ocean bottom in depths between 0 and 10 feet. We have identified a promising set of techniques that will exploit the electromagnetic, shape, texture, image, and vibratory- modal features of this images. During FY99 and FY00 we have worked toward refining these techniques. Signature data sets have been collected for a standard target set to facilitate the development of sensor fusion and target detection and classification algorithms. Specific behaviors, termed microbehaviors, are developed to utilize the robot's mobility to position and operate the sensors. A first generation, close-range sensor suite, composed of 5 sensors, will be completed and tested on a crawling platform in FY00, and will be further refined and demonstrated in FY01 as part of the Mine Countermeasures 6.3 core program sponsored by the Office of Naval Research.

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.

Study of an automatic trajectory following control system

NASA Technical Reports Server (NTRS)

Vanlandingham, H. F.; Moose, R. L.; Zwicke, P. E.; Lucas, W. H.; Brinkley, J. D.

1983-01-01

It is shown that the estimator part of the Modified Partitioned Adaptive Controller, (MPAC) developed for nonlinear aircraft dynamics of a small jet transport can adapt to sensor failures. In addition, an investigation is made into the potential usefulness of the configuration detection technique used in the MPAC and the failure detection filter is developed that determines how a noise plant output is associated with a line or plane characteristic of a failure. It is shown by computer simulation that the estimator part and the configuration detection part of the MPAC can readily adapt to actuator and sensor failures and that the failure detection filter technique cannot detect actuator or sensor failures accurately for this type of system because of the plant modeling errors. In addition, it is shown that the decision technique, developed for the failure detection filter, can accurately determine that the plant output is related to the characteristic line or plane in the presence of sensor noise.

Advanced Sensor Technologies for Next-Generation Vehicles

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

Sheen, S H; Chien, H T; Gopalsami, N

2002-01-30

This report summarizes the development of automobile emissions sensors at Argonne National Laboratory. Three types of sensor technologies, i.e., ultrasound, microwave, and ion-mobility spectrometry (IMS), were evaluated for engine-out emissions monitoring. Two acoustic sensor technologies, i.e., surface acoustic wave and flexural plate wave, were evaluated for detection of hydrocarbons. The microwave technique involves a cavity design and measures the shifts in resonance frequency that are a result of the presence of trace organic compounds. The IMS technique was chosen for further development into a practical emissions sensor. An IMS sensor with a radioactive {sup 63}Ni ion source was initially developedmore » and applied to measurement of hydrocarbons and NO{sub x} emissions. For practical applications, corona and spark discharge ion sources were later developed and applied to NO{sub x} emission measurement. The concentrations of NO{sub 2} in dry nitrogen and in a typical exhaust gas mixture are presented. The sensor response to moisture was evaluated, and a cooling method to control the moisture content in the gas stream was examined. Results show that the moisture effect can be reduced by using a thermoelectric cold plate. The design and performance of a laboratory prototype sensor are described.« less

An experimental study on the effect of temperature on piezoelectric sensors for impedance-based structural health monitoring.

PubMed

Baptista, Fabricio G; Budoya, Danilo E; de Almeida, Vinicius A D; Ulson, Jose Alfredo C

2014-01-10

The electromechanical impedance (EMI) technique is considered to be one of the most promising methods for developing structural health monitoring (SHM) systems. This technique is simple to implement and uses small and inexpensive piezoelectric sensors. However, practical problems have hindered its application to real-world structures, and temperature effects have been cited in the literature as critical problems. In this paper, we present an experimental study of the effect of temperature on the electrical impedance of the piezoelectric sensors used in the EMI technique. We used 5H PZT (lead zirconate titanate) ceramic sensors, which are commonly used in the EMI technique. The experimental results showed that the temperature effects were strongly frequency-dependent, which may motivate future research in the SHM field.

Biochemical component identification by plasmonic improved whispering gallery mode optical resonance based sensor

NASA Astrophysics Data System (ADS)

Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Saetchnikov, Anton V.; Schweiger, Gustav; Ostendorf, Andreas

2014-05-01

Experimental data on detection and identification of variety of biochemical agents, such as proteins, microelements, antibiotic of different generation etc. in both single and multi component solutions under varied in wide range concentration analyzed on the light scattering parameters of whispering gallery mode optical resonance based sensor are represented. Multiplexing on parameters and components has been realized using developed fluidic sensor cell with fixed in adhesive layer dielectric microspheres and data processing. Biochemical component identification has been performed by developed network analysis techniques. Developed approach is demonstrated to be applicable both for single agent and for multi component biochemical analysis. Novel technique based on optical resonance on microring structures, plasmon resonance and identification tools has been developed. To improve a sensitivity of microring structures microspheres fixed by adhesive had been treated previously by gold nanoparticle solution. Another technique used thin film gold layers deposited on the substrate below adhesive. Both biomolecule and nanoparticle injections caused considerable changes of optical resonance spectra. Plasmonic gold layers under optimized thickness also improve parameters of optical resonance spectra. Biochemical component identification has been also performed by developed network analysis techniques both for single and for multi component solution. So advantages of plasmon enhancing optical microcavity resonance with multiparameter identification tools is used for development of a new platform for ultra sensitive label-free biomedical sensor.

Optical control and diagnostics sensors for gas turbine machinery

NASA Astrophysics Data System (ADS)

Trolinger, James D.; Jenkins, Thomas P.; Heeg, Bauke

2012-10-01

There exists a vast range of optical techniques that have been under development for solving complex measurement problems related to gas-turbine machinery and phenomena. For instance, several optical techniques are ideally suited for studying fundamental combustion phenomena in laboratory environments. Yet other techniques hold significant promise for use as either on-line gas turbine control sensors, or as health monitoring diagnostics sensors. In this paper, we briefly summarize these and discuss, in more detail, some of the latter class of techniques, including phosphor thermometry, hyperspectral imaging and low coherence interferometry, which are particularly suited for control and diagnostics sensing on hot section components with ceramic thermal barrier coatings (TBCs).

Wearable sensor systems for infants.

PubMed

Zhu, Zhihua; Liu, Tao; Li, Guangyi; Li, Tong; Inoue, Yoshio

2015-02-05

Continuous health status monitoring of infants is achieved with the development and fusion of wearable sensing technologies, wireless communication techniques and a low energy-consumption microprocessor with high performance data processing algorithms. As a clinical tool applied in the constant monitoring of physiological parameters of infants, wearable sensor systems for infants are able to transmit the information obtained inside an infant's body to clinicians or parents. Moreover, such systems with integrated sensors can perceive external threats such as falling or drowning and warn parents immediately. Firstly, the paper reviews some available wearable sensor systems for infants; secondly, we introduce the different modules of the framework in the sensor systems; lastly, the methods and techniques applied in the wearable sensor systems are summarized and discussed. The latest research and achievements have been highlighted in this paper and the meaningful applications in healthcare and behavior analysis are also presented. Moreover, we give a lucid perspective of the development of wearable sensor systems for infants in the future.

Wearable Sensor Systems for Infants

PubMed Central

Zhu, Zhihua; Liu, Tao; Li, Guangyi; Li, Tong; Inoue, Yoshio

2015-01-01

Continuous health status monitoring of infants is achieved with the development and fusion of wearable sensing technologies, wireless communication techniques and a low energy-consumption microprocessor with high performance data processing algorithms. As a clinical tool applied in the constant monitoring of physiological parameters of infants, wearable sensor systems for infants are able to transmit the information obtained inside an infant's body to clinicians or parents. Moreover, such systems with integrated sensors can perceive external threats such as falling or drowning and warn parents immediately. Firstly, the paper reviews some available wearable sensor systems for infants; secondly, we introduce the different modules of the framework in the sensor systems; lastly, the methods and techniques applied in the wearable sensor systems are summarized and discussed. The latest research and achievements have been highlighted in this paper and the meaningful applications in healthcare and behavior analysis are also presented. Moreover, we give a lucid perspective of the development of wearable sensor systems for infants in the future. PMID:25664432

Extraction and evaluation of gas-flow-dependent features from dynamic measurements of gas sensors array

NASA Astrophysics Data System (ADS)

Kalinowski, Paweł; Woźniak, Łukasz; Jasiński, Grzegorz; Jasiński, Piotr

2016-11-01

Gas analyzers based on gas sensors are the devices which enable recognition of various kinds of volatile compounds. They have continuously been developed and investigated for over three decades, however there are still limitations which slow down the implementation of those devices in many applications. For example, the main drawbacks are the lack of selectivity, sensitivity and long term stability of those devices caused by the drift of utilized sensors. This implies the necessity of investigations not only in the field of development of gas sensors construction, but also the development of measurement procedures or methods of analysis of sensor responses which compensate the limitations of sensors devices. One of the fields of investigations covers the dynamic measurements of sensors or sensor-arrays response with the utilization of flow modulation techniques. Different gas delivery patterns enable the possibility of extraction of unique features which improves the stability and selectivity of gas detecting systems. In this article three utilized flow modulation techniques are presented, together with the proposition of the evaluation method of their usefulness and robustness in environmental pollutants detecting systems. The results of dynamic measurements of an commercially available TGS sensor array in the presence of nitrogen dioxide and ammonia are shown.

Innovative smart micro sensors for Army weaponry applications

NASA Astrophysics Data System (ADS)

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

2008-03-01

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

Hierarchical classification in high dimensional numerous class cases

NASA Technical Reports Server (NTRS)

Kim, Byungyong; Landgrebe, D. A.

1990-01-01

As progress in new sensor technology continues, increasingly high resolution imaging sensors are being developed. These sensors give more detailed and complex data for each picture element and greatly increase the dimensionality of data over past systems. Three methods for designing a decision tree classifier are discussed: a top down approach, a bottom up approach, and a hybrid approach. Three feature extraction techniques are implemented. Canonical and extended canonical techniques are mainly dependent upon the mean difference between two classes. An autocorrelation technique is dependent upon the correlation differences. The mathematical relationship between sample size, dimensionality, and risk value is derived.

Coast Guard's Response to Spilled Oil

ERIC Educational Resources Information Center

Ard, R. W., Jr.

1976-01-01

The Coast Guard utilizes a number of monitoring detectors, sensors, and techniques to find, recover and identify oil spills. Discussed in this article are in-situ and airborne sensors, systems developed to provide clean-up capability such as air deployable anti-pollution transfer system (ADAPTS), and techniques which will determine the source of a…

On-irrigator pasture soil moisture sensor

NASA Astrophysics Data System (ADS)

Eng-Choon Tan, Adrian; Richards, Sean; Platt, Ian; Woodhead, Ian

2017-02-01

In this paper, we presented the development of a proximal soil moisture sensor that measured the soil moisture content of dairy pasture directly from the boom of an irrigator. The proposed sensor was capable of soil moisture measurements at an accuracy of  ±5% volumetric moisture content, and at meter scale ground area resolutions. The sensor adopted techniques from the ultra-wideband radar to enable measurements of ground reflection at resolutions that are smaller than the antenna beamwidth of the sensor. An experimental prototype was developed for field measurements. Extensive field measurements using the developed prototype were conducted on grass pasture at different ground conditions to validate the accuracy of the sensor in performing soil moisture measurements.

Design and measurement technique of surface-enhanced Raman scattering for detection of bisphenol A

NASA Astrophysics Data System (ADS)

Abu Bakar, Norhayati; Mat Salleh, Muhamad; Umar, Akrajas Ali; Shapter, Joseph George

2017-06-01

Surface-enhanced Raman scattering (SERS) is a highly sensitive measurement technique that provides Raman peaks at different Raman shift for different molecule structures. The SERS sensor is potentially used to detect food contamination and monitor environmental pollutants. A self-developed SERS system for specific analysis with low development cost is a challenging issue. This study attempts to develop a simple SERS sensor system for detection of bisphenol A (BPA) molecule using SERS substrate of silver nanoplate film. A SERS sensor system was developed, consisting of a light source to excite analyte molecules, Inphotonic Raman probe, sensor chamber and spectrophotometer as an analyser system. A duplex fibre optic is used to transmit light from the source to the probe and from the probe to the spectrophotometer. For SERS measurement, BPA detection was done by comparing the Raman signal spectra of the BPA on the quartz substrate and BPA on the silver nanoplate film. This SERS sensor successfully sensed BPA with SERS enhancement factor (EF) 5.55  ×  103 and a detection limit of BPA concentration at 1 mM.

Sensor Data Qualification System (SDQS) Implementation Study

NASA Technical Reports Server (NTRS)

Wong, Edmond; Melcher, Kevin; Fulton, Christopher; Maul, William

2009-01-01

The Sensor Data Qualification System (SDQS) is being developed to provide a sensor fault detection capability for NASA s next-generation launch vehicles. In addition to traditional data qualification techniques (such as limit checks, rate-of-change checks and hardware redundancy checks), SDQS can provide augmented capability through additional techniques that exploit analytical redundancy relationships to enable faster and more sensitive sensor fault detection. This paper documents the results of a study that was conducted to determine the best approach for implementing a SDQS network configuration that spans multiple subsystems, similar to those that may be implemented on future vehicles. The best approach is defined as one that most minimizes computational resource requirements without impacting the detection of sensor failures.

Commercial Non-Dispersive Infrared Spectroscopy Sensors for Sub-Ambient Carbon Dioxide Detection

NASA Technical Reports Server (NTRS)

Swickrath, Michael J.; Anderson, Molly S.; McMillin, Summer; Broerman, Craig

2013-01-01

Carbon dioxide produced through respiration can accumulate rapidly within closed spaces. If not managed, a crew's respiratory rate increases, headaches and hyperventilation occur, vision and hearing are affected, and cognitive abilities decrease. Consequently, development continues on a number of CO2 removal technologies for human spacecraft and spacesuits. Terrestrially, technology development requires precise performance characterization to qualify promising air revitalization equipment. On-orbit, instrumentation is required to identify and eliminate unsafe conditions. This necessitates accurate in situ CO2 detection. Recursive compensation algorithms were developed for sub-ambient detection of CO2 with commercial off-the-shelf (COTS) non-dispersive infrared (NDIR) sensors. In addition, the source of the exponential loss in accuracy is developed theoretically. The basis of the loss can be explained through thermal, Doppler, and Lorentz broadening effects that arise as a result of the temperature, pressure, and composition of the gas mixture under analysis. The objective was to develop a mathematical routine to compensate COTS CO2 sensors relying on NDIR over pressures, temperatures, and compositions far from calibration conditions. The routine relies on a power-law relationship for the pressure dependency of the sensors along with an equivalent pressure to account for the composition dependency. A Newton-Raphson iterative technique solves for actual carbon dioxide concentration based on the reported concentration. Moreover, first principles routines were established to predict mixed-gas spectra based on sensor specifications (e.g., optical path length). The first principles model can be used to parametrically optimize sensors or sensor arrays across a wide variety of pressures/temperatures/ compositions. In this work, heuristic scaling arguments were utilized to develop reasonable compensation techniques. Experimental results confirmed this approach and provided evidence that composition broadening significantly alters spectra when pressure is reduced. Consequently, a recursive compensation technique was developed with the Newton-Raphson method, which was subsequently verified through experimentation.

Monitoring cure of composite resins using frequency dependent electromagnetic sensing techniques

NASA Technical Reports Server (NTRS)

Kranbuehl, D. E.; Hoff, M. S.; Loos, A. C.; Freeman, W. T., Jr.; Eichinger, D. A.

1988-01-01

A nondestructive in situ measurement technique has been developed for monitoring and measuring the cure processing properties of composite resins. Frequency dependent electromagnetic sensors (FDEMS) were used to directly measure resin viscosity during cure. The effects of the cure cycle and resin aging on the viscosity during cure were investigated using the sensor. Viscosity measurements obtained using the sensor are compared with the viscosities calculated by the Loos-Springer cure process model. Good overall agreement was obtained except for the aged resin samples.

Sensor Web Dynamic Measurement Techniques and Adaptive Observing Strategies

NASA Technical Reports Server (NTRS)

Talabac, Stephen J.

2004-01-01

Sensor Web observing systems may have the potential to significantly improve our ability to monitor, understand, and predict the evolution of rapidly evolving, transient, or variable environmental features and events. This improvement will come about by integrating novel data collection techniques, new or improved instruments, emerging communications technologies and protocols, sensor mark-up languages, and interoperable planning and scheduling systems. In contrast to today's observing systems, "event-driven" sensor webs will synthesize real- or near-real time measurements and information from other platforms and then react by reconfiguring the platforms and instruments to invoke new measurement modes and adaptive observation strategies. Similarly, "model-driven" sensor webs will utilize environmental prediction models to initiate targeted sensor measurements or to use a new observing strategy. The sensor web concept contrasts with today's data collection techniques and observing system operations concepts where independent measurements are made by remote sensing and in situ platforms that do not share, and therefore cannot act upon, potentially useful complementary sensor measurement data and platform state information. This presentation describes NASA's view of event-driven and model-driven Sensor Webs and highlights several research and development activities at the Goddard Space Flight Center.

Manufacturing Demonstration Facility: Roll-to-Roll Processing

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

Datskos, Panos G; Joshi, Pooran C; List III, Frederick Alyious

This Manufacturing Demonstration Facility (MDF)e roll-to-roll processing effort described in this report provided an excellent opportunity to investigate a number of advanced manufacturing approaches to achieve a path for low cost devices and sensors. Critical to this effort is the ability to deposit thin films at low temperatures using nanomaterials derived from nanofermentation. The overarching goal of this project was to develop roll-to-roll manufacturing processes of thin film deposition on low-cost flexible substrates for electronics and sensor applications. This project utilized ORNL s unique Pulse Thermal Processing (PTP) technologies coupled with non-vacuum low temperature deposition techniques, ORNL s clean roommore » facility, slot dye coating, drop casting, spin coating, screen printing and several other equipment including a Dimatix ink jet printer and a large-scale Kyocera ink jet printer. The roll-to-roll processing project had three main tasks: 1) develop and demonstrate zinc-Zn based opto-electronic sensors using low cost nanoparticulate structures manufactured in a related MDF Project using nanofermentation techniques, 2) evaluate the use of silver based conductive inks developed by project partner NovaCentrix for electronic device fabrication, and 3) demonstrate a suite of low cost printed sensors developed using non-vacuum deposition techniques which involved the integration of metal and semiconductor layers to establish a diverse sensor platform technology.« less

An Enzyme-Induced Novel Biosensor for the Sensitive Electrochemical Determination of Isoniazid

PubMed Central

Chokkareddy, Rajasekhar; Bhajanthri, Natesh Kumar; Redhi, Gan G.

2017-01-01

In this present work, a glassy carbon electrode (GCE) was modified primarily with multiwalled carbon nanotubes (MWCNTs) and a composite of MWCNTs and titanium oxide nanoparticles (TiO2NPs). The enzyme horseradish peroxidase (HRP) was immobilized to enhance the sensing ability of GCE. The proposed biosensor was used for the sensitive determination of isoniazid (INZ) in various pharmaceutical samples. The electrochemical behaviour of the developed MWCNT-TiO2NPs-HRP-GCE biosensor was studied by using cyclic voltammetry (CV) and differential pulse voltammetric (DPV) techniques. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetry (TGA) and transmission electron microscopy (TEM) techniques were used to characterize the developed sensor. Phosphate buffer solution (PBS) with pH 7 was used as supporting electrolyte in the present investigation. The cyclic voltammetric results revealed that the increment of anodic peak currents for the enzyme-induced sensor was almost 8-fold greater than that of a bare GCE. The DPV technique exhibited good limit of detection and limit of quantification values, viz., 0.0335 μM and 0.1118 μM, respectively. Moreover, the developed sensor showed long-lasting stability and repeatability without any interferents. This strongly indicates that the fabricated sensor shows outstanding electrochemical performance towards INZ, with excellent selectivity and sensitivity. The developed sensor was successfully applied to pharmaceutical samples and gave good percentages of recoveries. PMID:28587260

EVAL mission requirements, phase 1

NASA Technical Reports Server (NTRS)

1976-01-01

The aspects of NASA's applications mission were enhanced by utilization of shuttle/spacelab, and payload groupings which optimize the cost of achieving the mission goals were defined. Preliminary Earth Viewing Application Laboratory (EVAL) missions, experiments, sensors, and sensor groupings were developed. The major technological EVAL themes and objectives which NASA will be addressing during the 1980 to 2,000 time period were investigated. Missions/experiments which addressed technique development, sensor development, application development, and/or operational data collection were considered as valid roles for EVAL flights.

CMOS-MEMS Chemiresistive and Chemicapacitive Chemical Sensor System

NASA Astrophysics Data System (ADS)

Lazarus, Nathan S.

Integrating chemical sensors with testing electronics is a powerful technique with the potential to lower power and cost and allow for lower system limits of detection. This thesis explores the possibility of creating an integrated sensor system intended to be embedded within respirator cartridges to notify the user that hazardous chemicals will soon leak into the face mask. For a chemical sensor designer, this application is particularly challenging due to the need for a very sensitive and cheap sensor that will be exposed to widely varying environmental conditions during use. An octanethiol-coated gold nanoparticle chemiresistor to detect industrial solvents is developed, focusing on characterizing the environmental stability and limits of detection of the sensor. Since the chemiresistor was found to be highly sensitive to water vapor, a series of highly sensitive humidity sensor topologies were developed, with sensitivities several times previous integrated capacitive humidity sensors achieved. Circuit techniques were then explored to reduce the humidity sensor limits of detection, including the analysis of noise, charge injection, jitter and clock feedthrough in a charge-based capacitance measurement (CBCM) circuit and the design of a low noise Colpitts LC oscillator. The characterization of high resistance gold nanoclusters for capacitive chemical sensing was also performed. In the final section, a preconcentrator, a heater element intended to release a brief concentrated pulse of analate, was developed and tested for the purposes of lowering the system limit of detection.

Oceanographic satellite remote sensing: Registration, rectification, and data integration requirements

NASA Technical Reports Server (NTRS)

Nichols, D. A.

1982-01-01

The problem of data integration in oceanography is discussed. Recommendations are made for technique development and evaluation, understanding requirements, and packaging techniques for speed, efficiency and ease of use. The primary satellite sensors of interest to oceanography are summarized. It is concluded that imaging type sensors make image processing an important tool for oceanographic studies.

Developing sensor activity relationships for the JPL electronic nose sensors using molecular modeling and QSAR techniques

NASA Technical Reports Server (NTRS)

Shevade, A. V.; Ryan, M. A.; Homer, M. L.; Jewell, A. D.; Zhou, H.; Manatt, K.; Kisor, A. K.

2005-01-01

We report a Quantitative Structure-Activity Relationships (QSAR) study using Genetic Function Approximations (GFA) to describe the polymer-carbon composite sensor activities in the JPL Electronic Nose, when exposed to chemical vapors at parts-per-million concentration levels.

Analysis and optimal design of moisture sensor for rice grain moisture measurement

NASA Astrophysics Data System (ADS)

Jain, Sweety; Mishra, Pankaj Kumar; Thakare, Vandana Vikas

2018-04-01

The analysis and design of a microstrip sensor for accurate determination of moisture content (MC) in rice grains based on oven drying technique, this technique is easy, fast and less time-consuming to other techniques. The sensor is designed with low insertion loss, reflection coefficient and maximum gain is -35dB and 5.88dB at 2.68GHz as well as discussed all the parameters such as axial ratio, maximum gain, smith chart etc, which is helpful for analysis the moisture measurement. The variation in percentage of moisture measurement with magnitude and phase of transmission coefficient is investigated at selected frequencies. The microstrip moisture sensor consists of one layer: substrate FR4, thickness 1.638 is simulated by computer simulated technology microwave studio (CST MWS). It is concluded that the proposed sensor is suitable for development as a complete sensor and to estimate the optimum moisture content of rice grains with accurately, sensitivity, compact, versatile and suitable for determining the moisture content of other crops and agriculture products.

Sensor Fusion and Smart Sensor in Sports and Biomedical Applications.

PubMed

Mendes, José Jair Alves; Vieira, Mário Elias Marinho; Pires, Marcelo Bissi; Stevan, Sergio Luiz

2016-09-23

The following work presents an overview of smart sensors and sensor fusion targeted at biomedical applications and sports areas. In this work, the integration of these areas is demonstrated, promoting a reflection about techniques and applications to collect, quantify and qualify some physical variables associated with the human body. These techniques are presented in various biomedical and sports applications, which cover areas related to diagnostics, rehabilitation, physical monitoring, and the development of performance in athletes, among others. Although some applications are described in only one of two fields of study (biomedicine and sports), it is very likely that the same application fits in both, with small peculiarities or adaptations. To illustrate the contemporaneity of applications, an analysis of specialized papers published in the last six years has been made. In this context, the main characteristic of this review is to present the largest quantity of relevant examples of sensor fusion and smart sensors focusing on their utilization and proposals, without deeply addressing one specific system or technique, to the detriment of the others.

Novel E-Field Sensor for Projectile Detection

DTIC Science & Technology

2012-10-22

aircrafts. They used an array of three plate induction sensors and a simple algorithm to deter mine the direction of the planes [9]. In more recent...publications [10, 11, 12] researchers present increasingly more advanced algorithms and sensors. The techniques developed thus far have not received...the electric field pulse is being detected by a group of sensors in array with known distances between the sensors, so triangulation algorithms could

A study for hypergolic vapor sensor development

NASA Technical Reports Server (NTRS)

Stetter, J. R.

1977-01-01

The use of an electrochemical technique for MMH and N02 measurement was investigated. Specific MMH and N02 electrochemical sensors were developed. Experimental techniques for preparation, handling, and analysis of hydrazine's vapor mixtures at ppb and ppm levels were developed. Two approaches to N02 instrument design were evaluated including specific adsorption and specific electrochemical reduction. Two approaches to hydrazines monitoring were evaluated including catalytic conversion to N0 with subsequent N0 detection and direct specific electrochemical oxidation. Two engineering prototype MMH/N02 monitors were designed and constructed.

Multipath Routing in Wireless Sensor Networks: Survey and Research Challenges

PubMed Central

Radi, Marjan; Dezfouli, Behnam; Bakar, Kamalrulnizam Abu; Lee, Malrey

2012-01-01

A wireless sensor network is a large collection of sensor nodes with limited power supply and constrained computational capability. Due to the restricted communication range and high density of sensor nodes, packet forwarding in sensor networks is usually performed through multi-hop data transmission. Therefore, routing in wireless sensor networks has been considered an important field of research over the past decade. Nowadays, multipath routing approach is widely used in wireless sensor networks to improve network performance through efficient utilization of available network resources. Accordingly, the main aim of this survey is to present the concept of the multipath routing approach and its fundamental challenges, as well as the basic motivations for utilizing this technique in wireless sensor networks. In addition, we present a comprehensive taxonomy on the existing multipath routing protocols, which are especially designed for wireless sensor networks. We highlight the primary motivation behind the development of each protocol category and explain the operation of different protocols in detail, with emphasis on their advantages and disadvantages. Furthermore, this paper compares and summarizes the state-of-the-art multipath routing techniques from the network application point of view. Finally, we identify open issues for further research in the development of multipath routing protocols for wireless sensor networks. PMID:22368490

Multipath routing in wireless sensor networks: survey and research challenges.

PubMed

Radi, Marjan; Dezfouli, Behnam; Abu Bakar, Kamalrulnizam; Lee, Malrey

2012-01-01

A wireless sensor network is a large collection of sensor nodes with limited power supply and constrained computational capability. Due to the restricted communication range and high density of sensor nodes, packet forwarding in sensor networks is usually performed through multi-hop data transmission. Therefore, routing in wireless sensor networks has been considered an important field of research over the past decade. Nowadays, multipath routing approach is widely used in wireless sensor networks to improve network performance through efficient utilization of available network resources. Accordingly, the main aim of this survey is to present the concept of the multipath routing approach and its fundamental challenges, as well as the basic motivations for utilizing this technique in wireless sensor networks. In addition, we present a comprehensive taxonomy on the existing multipath routing protocols, which are especially designed for wireless sensor networks. We highlight the primary motivation behind the development of each protocol category and explain the operation of different protocols in detail, with emphasis on their advantages and disadvantages. Furthermore, this paper compares and summarizes the state-of-the-art multipath routing techniques from the network application point of view. Finally, we identify open issues for further research in the development of multipath routing protocols for wireless sensor networks.

Development of Meandering Winding Magnetometer (MWM (Register Trademark)) Eddy Current Sensors for the Health Monitoring, Modeling and Damage Detection of High Temperature Composite Materials

NASA Technical Reports Server (NTRS)

Russell, Richard; Washabaugh, Andy; Sheiretov, Yanko; Martin, Christopher; Goldfine, Neil

2011-01-01

The increased use of high-temperature composite materials in modern and next generation aircraft and spacecraft have led to the need for improved nondestructive evaluation and health monitoring techniques. Such technologies are desirable to improve quality control, damage detection, stress evaluation and temperature measurement capabilities. Novel eddy current sensors and sensor arrays, such as Meandering Winding Magnetometers (MWMs) have provided alternate or complimentary techniques to ultrasound and thermography for both nondestructive evaluation (NDE) and structural health monitoring (SHM). This includes imaging of composite material quality, damage detection and .the monitoring of fiber temperatures and multidirectional stresses. Historically, implementation of MWM technology for the inspection of the Space Shuttle Orbiter Reinforced Carbon-Carbon Composite (RCC) leading edge panels was developed by JENTEK Sensors and was subsequently transitioned by NASA as an operational pre and post flight in-situ inspection at the Kennedy Space Center. A manual scanner, which conformed'automatically to the curvature of the RCC panels was developed and used as a secondary technique if a defect was found during an infrared thermography screening, During a recent proof of concept study on composite overwrapped pressure vessels (COPV's), three different MWM sensors were tested at three orientations to demonstrate the ability of the technology to measure stresses at various fiber orientations and depths. These results showed excellent correlation with actual surface strain gage measurements. Recent advancements of this technology have been made applying MWM sensor technology for scanning COPVs for mechanical damage. This presentation will outline the recent advance in the MWM.technology and the development of MWM techniques for NDE and SHM of carbon wraped composite overwrapped pressure vessels (COPVs) including the measurement of internal stresses via a surface mounted sensor array. In addition, this paper will outline recent efforts to produce sensors capable of making real-time measurements at temperatures up to 850 C, and discuss previous results demonstrating capability to monitor carbon fiber temperature changes within a composite material.

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.

Non-Destructive Techniques Based on Eddy Current Testing

PubMed Central

García-Martín, Javier; Gómez-Gil, Jaime; Vázquez-Sánchez, Ernesto

2011-01-01

Non-destructive techniques are used widely in the metal industry in order to control the quality of materials. Eddy current testing is one of the most extensively used non-destructive techniques for inspecting electrically conductive materials at very high speeds that does not require any contact between the test piece and the sensor. This paper includes an overview of the fundamentals and main variables of eddy current testing. It also describes the state-of-the-art sensors and modern techniques such as multi-frequency and pulsed systems. Recent advances in complex models towards solving crack-sensor interaction, developments in instrumentation due to advances in electronic devices, and the evolution of data processing suggest that eddy current testing systems will be increasingly used in the future. PMID:22163754

Non-destructive techniques based on eddy current testing.

PubMed

García-Martín, Javier; Gómez-Gil, Jaime; Vázquez-Sánchez, Ernesto

2011-01-01

Non-destructive techniques are used widely in the metal industry in order to control the quality of materials. Eddy current testing is one of the most extensively used non-destructive techniques for inspecting electrically conductive materials at very high speeds that does not require any contact between the test piece and the sensor. This paper includes an overview of the fundamentals and main variables of eddy current testing. It also describes the state-of-the-art sensors and modern techniques such as multi-frequency and pulsed systems. Recent advances in complex models towards solving crack-sensor interaction, developments in instrumentation due to advances in electronic devices, and the evolution of data processing suggest that eddy current testing systems will be increasingly used in the future.

Polydimethylsiloxane pressure sensors for force analysis in tension band wiring of the olecranon.

PubMed

Zens, Martin; Goldschmidtboeing, Frank; Wagner, Ferdinand; Reising, Kilian; Südkamp, Norbert P; Woias, Peter

2016-11-14

Several different surgical techniques are used in the treatment of olecranon fractures. Tension band wiring is one of the most preferred options by surgeons worldwide. The concept of this technique is to transform a tensile force into a compression force that adjoins two surfaces of a fractured bone. Currently, little is known about the resulting compression force within a fracture. Sensor devices are needed that directly transduce the compression force into a measurement quality. This allows the comparison of different surgical techniques. Ideally the sensor devices ought to be placed in the gap between the fractured segments. The design, development and characterization of miniaturized pressure sensors fabricated entirely from polydimethylsiloxane (PDMS) for a placement within a fracture is presented. The pressure sensors presented in this work are tested, calibrated and used in an experimental in vitro study. The pressure sensors are highly sensitive with an accuracy of approximately 3 kPa. A flexible fabrication process for various possible applications is described. The first in vitro study shows that using a single-twist or double-twist technique in tension band wiring of the olecranon has no significant effect on the resulting compression forces. The in vitro study shows the feasibility of the proposed measurement technique and the results of a first exemplary study.

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.

Pressure sensor to determine spatial pressure distributions on boundary layer flows

NASA Astrophysics Data System (ADS)

Sciammarella, Cesar A.; Piroozan, Parham; Corke, Thomas C.

1997-03-01

The determination of pressures along the surface of a wind tunnel proves difficult with methods that must introduce devices into the flow stream. This paper presents a sensor that is part of the wall. A special interferometric reflection moire technique is developed and used to produce signals that measures pressure both in static and dynamic settings. The sensor developed is an intelligent sensor that combines optics and electronics to analyze the pressure patterns. The sensor provides the input to a control system that is capable of modifying the shape of the wall and preserve the stability of the flow.

Micro-patterning and characterization of PHEMA-co-PAM-based optical chemical sensors for lab-on-a-chip applications.

PubMed

Zhu, Haixin; Zhou, Xianfeng; Su, Fengyu; Tian, Yanqing; Ashili, Shashanka; Holl, Mark R; Meldrum, Deirdre R

2012-10-01

We report a novel method for wafer level, high throughput optical chemical sensor patterning, with precise control of the sensor volume and capability of producing arbitrary microscale patterns. Monomeric oxygen (O(2)) and pH optical probes were polymerized with 2-hydroxyethyl methacrylate (HEMA) and acrylamide (AM) to form spin-coatable and further crosslinkable polymers. A micro-patterning method based on micro-fabrication techniques (photolithography, wet chemical process and reactive ion etch) was developed to miniaturize the sensor film onto glass substrates in arbitrary sizes and shapes. The sensitivity of fabricated micro-patterns was characterized under various oxygen concentrations and pH values. The process for spatially integration of two sensors (Oxygen and pH) on the same substrate surface was also developed, and preliminary fabrication and characterization results were presented. To the best of our knowledge, it is the first time that poly (2-hydroxylethyl methacrylate)-co-poly (acrylamide) (PHEMA-co-PAM)-based sensors had been patterned and integrated at the wafer level with micron scale precision control using microfabrication techniques. The developed methods can provide a feasible way to miniaturize and integrate the optical chemical sensor system and can be applied to any lab-on-a-chip system, especially the biological micro-systems requiring optical sensing of single or multiple analytes.

Machine vision guided sensor positioning system for leaf temperature assessment

NASA Technical Reports Server (NTRS)

Kim, Y.; Ling, P. P.; Janes, H. W. (Principal Investigator)

2001-01-01

A sensor positioning system was developed for monitoring plants' well-being using a non-contact sensor. Image processing algorithms were developed to identify a target region on a plant leaf. A novel algorithm to recover view depth was developed by using a camera equipped with a computer-controlled zoom lens. The methodology has improved depth recovery resolution over a conventional monocular imaging technique. An algorithm was also developed to find a maximum enclosed circle on a leaf surface so the conical field-of-view of an infrared temperature sensor could be filled by the target without peripheral noise. The center of the enclosed circle and the estimated depth were used to define the sensor 3-D location for accurate plant temperature measurement.

Desensitized Optimal Filtering and Sensor Fusion Toolkit

NASA Technical Reports Server (NTRS)

Karlgaard, Christopher D.

2015-01-01

Analytical Mechanics Associates, Inc., has developed a software toolkit that filters and processes navigational data from multiple sensor sources. A key component of the toolkit is a trajectory optimization technique that reduces the sensitivity of Kalman filters with respect to model parameter uncertainties. The sensor fusion toolkit also integrates recent advances in adaptive Kalman and sigma-point filters for non-Gaussian problems with error statistics. This Phase II effort provides new filtering and sensor fusion techniques in a convenient package that can be used as a stand-alone application for ground support and/or onboard use. Its modular architecture enables ready integration with existing tools. A suite of sensor models and noise distribution as well as Monte Carlo analysis capability are included to enable statistical performance evaluations.

Aerospace Sensor Systems: From Sensor Development To Vehicle Application

NASA Technical Reports Server (NTRS)

Hunter, Gary W.

2008-01-01

This paper presents an overview of years of sensor system development and application for aerospace systems. The emphasis of this work is on developing advanced capabilities for measurement and control of aeropropulsion and crew vehicle systems as well as monitoring the safety of those systems. Specific areas of work include chemical species sensors, thin film thermocouples and strain gages, heat flux gages, fuel gages, SiC based electronic devices and sensors, space qualified electronics, and MicroElectroMechanical Systems (MEMS) as well as integrated and multifunctional sensor systems. Each sensor type has its own technical challenges related to integration and reliability in a given application. The general approach has been to develop base sensor technology using microfabrication techniques, integrate sensors with "smart" hardware and software, and demonstrate those systems in a range of aerospace applications. Descriptions of the sensor elements, their integration into sensors systems, and examples of sensor system applications will be discussed. Finally, suggestions related to the future of sensor technology will be given. It is concluded that smart micro/nano sensor technology can revolutionize aerospace applications, but significant challenges exist in maturing the technology and demonstrating its value in real-life applications.

Objective measures, sensors and computational techniques for stress recognition and classification: a survey.

PubMed

Sharma, Nandita; Gedeon, Tom

2012-12-01

Stress is a major growing concern in our day and age adversely impacting both individuals and society. Stress research has a wide range of benefits from improving personal operations, learning, and increasing work productivity to benefiting society - making it an interesting and socially beneficial area of research. This survey reviews sensors that have been used to measure stress and investigates techniques for modelling stress. It discusses non-invasive and unobtrusive sensors for measuring computed stress, a term we coin in the paper. Sensors that do not impede everyday activities that could be used by those who would like to monitor stress levels on a regular basis (e.g. vehicle drivers, patients with illnesses linked to stress) is the focus of the discussion. Computational techniques have the capacity to determine optimal sensor fusion and automate data analysis for stress recognition and classification. Several computational techniques have been developed to model stress based on techniques such as Bayesian networks, artificial neural networks, and support vector machines, which this survey investigates. The survey concludes with a summary and provides possible directions for further computational stress research. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Development and Ground-Test Validation of Fiber Optic Sensor Attachment Techniques for Hot Structures Applications

NASA Technical Reports Server (NTRS)

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

2005-01-01

Fiber Optic Strain Measurements: a) Successfully attached silica fiber optic sensors to both metallics and composites; b) Accomplished valid EFPI strain measurements to 1850 F; c) Successfully attached EFPI sensors to large scale hot-structures; and d) Attached and thermally validated FBG bond and epsilon(sub app). Future Development a) Improve characterization of sensors on C-C and C-SiC substrates; b) Apply application to other composites such as SiC-SiC; c) Assist development of interferometer based Sapphire sensor currently being conducted under a Phase II SBIR; and d) Complete combined thermal/mechanical testing of FBG on composite substrates in controlled laboratory environment.

Holographic detection of hydrocarbon gases and other volatile organic compounds.

PubMed

Martínez-Hurtado, J L; Davidson, C A B; Blyth, J; Lowe, C R

2010-10-05

There is a need to develop sensors for real-time monitoring of volatile organic compounds (VOCs) and hydrocarbon gases in both external and indoor environments, since these compounds are of growing concern in human health and welfare. Current measurement technology for VOCs requires sophisticated equipment and lacks the prospect for rapid real-time monitoring. Holographic sensors can give a direct reading of the analyte concentration as a color change. We report a technique for recording holographic sensors by laser ablation of silver particles formed in situ by diffusion. This technique allows a readily available hydrophobic silicone elastomer to be transformed into an effective sensor for hydrocarbon gases and other volatile compounds. The intermolecular interactions present between the polymer and molecules are used to predict the sensor performance. The hydrophobicity of this material allows the sensor to operate without interference from water and other atmospheric gases and thus makes the sensor suitable for biomedical, industrial, or environmental analysis.

New sensors and techniques for the structural health monitoring of propulsion systems.

PubMed

Woike, Mark; Abdul-Aziz, Ali; Oza, Nikunj; Matthews, Bryan

2013-01-01

The ability to monitor the structural health of the rotating components, especially in the hot sections of turbine engines, is of major interest to aero community in improving engine safety and reliability. The use of instrumentation for these applications remains very challenging. It requires sensors and techniques that are highly accurate, are able to operate in a high temperature environment, and can detect minute changes and hidden flaws before catastrophic events occur. The National Aeronautics and Space Administration (NASA), through the Aviation Safety Program (AVSP), has taken a lead role in the development of new sensor technologies and techniques for the in situ structural health monitoring of gas turbine engines. This paper presents a summary of key results and findings obtained from three different structural health monitoring approaches that have been investigated. This includes evaluating the performance of a novel microwave blade tip clearance sensor; a vibration based crack detection technique using an externally mounted capacitive blade tip clearance sensor; and lastly the results of using data driven anomaly detection algorithms for detecting cracks in a rotating disk.

New Sensors and Techniques for the Structural Health Monitoring of Propulsion Systems

PubMed Central

2013-01-01

The ability to monitor the structural health of the rotating components, especially in the hot sections of turbine engines, is of major interest to aero community in improving engine safety and reliability. The use of instrumentation for these applications remains very challenging. It requires sensors and techniques that are highly accurate, are able to operate in a high temperature environment, and can detect minute changes and hidden flaws before catastrophic events occur. The National Aeronautics and Space Administration (NASA), through the Aviation Safety Program (AVSP), has taken a lead role in the development of new sensor technologies and techniques for the in situ structural health monitoring of gas turbine engines. This paper presents a summary of key results and findings obtained from three different structural health monitoring approaches that have been investigated. This includes evaluating the performance of a novel microwave blade tip clearance sensor; a vibration based crack detection technique using an externally mounted capacitive blade tip clearance sensor; and lastly the results of using data driven anomaly detection algorithms for detecting cracks in a rotating disk. PMID:23935425

Transient plasma estimation: a noise cancelling/identification approach

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

Candy, J.V.; Casper, T.; Kane, R.

1985-03-01

The application of a noise cancelling technique to extract energy storage information from sensors occurring during fusion reactor experiments on the Tandem Mirror Experiment-Upgrade (TMX-U) at the Lawrence Livermore National Laboratory (LLNL) is examined. We show how this technique can be used to decrease the uncertainty in the corresponding sensor measurements used for diagnostics in both real-time and post-experimental environments. We analyze the performance of algorithm on the sensor data and discuss the various tradeoffs. The algorithm suggested is designed using SIG, an interactive signal processing package developed at LLNL.

Cross-sensor iris recognition through kernel learning.

PubMed

Pillai, Jaishanker K; Puertas, Maria; Chellappa, Rama

2014-01-01

Due to the increasing popularity of iris biometrics, new sensors are being developed for acquiring iris images and existing ones are being continuously upgraded. Re-enrolling users every time a new sensor is deployed is expensive and time-consuming, especially in applications with a large number of enrolled users. However, recent studies show that cross-sensor matching, where the test samples are verified using data enrolled with a different sensor, often lead to reduced performance. In this paper, we propose a machine learning technique to mitigate the cross-sensor performance degradation by adapting the iris samples from one sensor to another. We first present a novel optimization framework for learning transformations on iris biometrics. We then utilize this framework for sensor adaptation, by reducing the distance between samples of the same class, and increasing it between samples of different classes, irrespective of the sensors acquiring them. Extensive evaluations on iris data from multiple sensors demonstrate that the proposed method leads to improvement in cross-sensor recognition accuracy. Furthermore, since the proposed technique requires minimal changes to the iris recognition pipeline, it can easily be incorporated into existing iris recognition systems.

STUDY AND INVESTIGATION OF A TECHNIQUE FOR EVALUATING SURVEILLANCE SENSOR PERFORMANCE.

DTIC Science & Technology

noncoherent optical correlator is suggested as the most feasible implementation. Conclusions supporting the feasibility of the technique are given followed by recommendations for further development of the evaluation technique.

Spline function approximation techniques for image geometric distortion representation. [for registration of multitemporal remote sensor imagery

NASA Technical Reports Server (NTRS)

Anuta, P. E.

1975-01-01

Least squares approximation techniques were developed for use in computer aided correction of spatial image distortions for registration of multitemporal remote sensor imagery. Polynomials were first used to define image distortion over the entire two dimensional image space. Spline functions were then investigated to determine if the combination of lower order polynomials could approximate a higher order distortion with less computational difficulty. Algorithms for generating approximating functions were developed and applied to the description of image distortion in aircraft multispectral scanner imagery. Other applications of the techniques were suggested for earth resources data processing areas other than geometric distortion representation.

Advanced optical position sensors for magnetically suspended wind tunnel models

NASA Technical Reports Server (NTRS)

Lafleur, S.

1985-01-01

A major concern to aerodynamicists has been the corruption of wind tunnel test data by model support structures, such as stings or struts. A technique for magnetically suspending wind tunnel models was considered by Tournier and Laurenceau (1957) in order to overcome this problem. This technique is now implemented with the aid of a Large Magnetic Suspension and Balance System (LMSBS) and advanced position sensors for measuring model attitude and position within the test section. Two different optical position sensors are discussed, taking into account a device based on the use of linear CCD arrays, and a device utilizing area CID cameras. Current techniques in image processing have been employed to develop target tracking algorithms capable of subpixel resolution for the sensors. The algorithms are discussed in detail, and some preliminary test results are reported.

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

NASA Astrophysics Data System (ADS)

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

2011-02-01

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

Intelligent Sensors for Atomization Processing of Molten Metals and Alloys

DTIC Science & Technology

1988-06-01

20ff. 12. Hirleman, Dan E. Particle Sizing by Optical , Nonimaging Techniques. Liquid Particle Size Measurement Techniques, ASTM, 1984, pp. 35ff. 13...sensors are based on electric, electromagnetic or optical principles, the latter being most developed in fields obviously related to atomization. Optical ...beams to observe various interference, diffraction, and heterodyning effects, and to observe, with high signal-to-noise ratio, even weak optical

Adaptive inferential sensors based on evolving fuzzy models.

PubMed

Angelov, Plamen; Kordon, Arthur

2010-04-01

A new technique to the design and use of inferential sensors in the process industry is proposed in this paper, which is based on the recently introduced concept of evolving fuzzy models (EFMs). They address the challenge that the modern process industry faces today, namely, to develop such adaptive and self-calibrating online inferential sensors that reduce the maintenance costs while keeping the high precision and interpretability/transparency. The proposed new methodology makes possible inferential sensors to recalibrate automatically, which reduces significantly the life-cycle efforts for their maintenance. This is achieved by the adaptive and flexible open-structure EFM used. The novelty of this paper lies in the following: (1) the overall concept of inferential sensors with evolving and self-developing structure from the data streams; (2) the new methodology for online automatic selection of input variables that are most relevant for the prediction; (3) the technique to detect automatically a shift in the data pattern using the age of the clusters (and fuzzy rules); (4) the online standardization technique used by the learning procedure of the evolving model; and (5) the application of this innovative approach to several real-life industrial processes from the chemical industry (evolving inferential sensors, namely, eSensors, were used for predicting the chemical properties of different products in The Dow Chemical Company, Freeport, TX). It should be noted, however, that the methodology and conclusions of this paper are valid for the broader area of chemical and process industries in general. The results demonstrate that well-interpretable and with-simple-structure inferential sensors can automatically be designed from the data stream in real time, which predict various process variables of interest. The proposed approach can be used as a basis for the development of a new generation of adaptive and evolving inferential sensors that can address the challenges of the modern advanced process industry.

A Radiosonde Using a Humidity Sensor Array with a Platinum Resistance Heater and Multi-Sensor Data Fusion

PubMed Central

Shi, Yunbo; Luo, Yi; Zhao, Wenjie; Shang, Chunxue; Wang, Yadong; Chen, Yinsheng

2013-01-01

This paper describes the design and implementation of a radiosonde which can measure the meteorological temperature, humidity, pressure, and other atmospheric data. The system is composed of a CPU, microwave module, temperature sensor, pressure sensor and humidity sensor array. In order to effectively solve the humidity sensor condensation problem due to the low temperatures in the high altitude environment, a capacitive humidity sensor including four humidity sensors to collect meteorological humidity and a platinum resistance heater was developed using micro-electro-mechanical-system (MEMS) technology. A platinum resistance wire with 99.999% purity and 0.023 mm in diameter was used to obtain the meteorological temperature. A multi-sensor data fusion technique was applied to process the atmospheric data. Static and dynamic experimental results show that the designed humidity sensor with platinum resistance heater can effectively tackle the sensor condensation problem, shorten response times and enhance sensitivity. The humidity sensor array can improve measurement accuracy and obtain a reliable initial meteorological humidity data, while the multi-sensor data fusion technique eliminates the uncertainty in the measurement. The radiosonde can accurately reflect the meteorological changes. PMID:23857263

A radiosonde using a humidity sensor array with a platinum resistance heater and multi-sensor data fusion.

PubMed

Shi, Yunbo; Luo, Yi; Zhao, Wenjie; Shang, Chunxue; Wang, Yadong; Chen, Yinsheng

2013-07-12

This paper describes the design and implementation of a radiosonde which can measure the meteorological temperature, humidity, pressure, and other atmospheric data. The system is composed of a CPU, microwave module, temperature sensor, pressure sensor and humidity sensor array. In order to effectively solve the humidity sensor condensation problem due to the low temperatures in the high altitude environment, a capacitive humidity sensor including four humidity sensors to collect meteorological humidity and a platinum resistance heater was developed using micro-electro-mechanical-system (MEMS) technology. A platinum resistance wire with 99.999% purity and 0.023 mm in diameter was used to obtain the meteorological temperature. A multi-sensor data fusion technique was applied to process the atmospheric data. Static and dynamic experimental results show that the designed humidity sensor with platinum resistance heater can effectively tackle the sensor condensation problem, shorten response times and enhance sensitivity. The humidity sensor array can improve measurement accuracy and obtain a reliable initial meteorological humidity data, while the multi-sensor data fusion technique eliminates the uncertainty in the measurement. The radiosonde can accurately reflect the meteorological changes.

Sensor Fusion and Smart Sensor in Sports and Biomedical Applications

PubMed Central

Mendes, José Jair Alves; Vieira, Mário Elias Marinho; Pires, Marcelo Bissi; Stevan, Sergio Luiz

2016-01-01

The following work presents an overview of smart sensors and sensor fusion targeted at biomedical applications and sports areas. In this work, the integration of these areas is demonstrated, promoting a reflection about techniques and applications to collect, quantify and qualify some physical variables associated with the human body. These techniques are presented in various biomedical and sports applications, which cover areas related to diagnostics, rehabilitation, physical monitoring, and the development of performance in athletes, among others. Although some applications are described in only one of two fields of study (biomedicine and sports), it is very likely that the same application fits in both, with small peculiarities or adaptations. To illustrate the contemporaneity of applications, an analysis of specialized papers published in the last six years has been made. In this context, the main characteristic of this review is to present the largest quantity of relevant examples of sensor fusion and smart sensors focusing on their utilization and proposals, without deeply addressing one specific system or technique, to the detriment of the others. PMID:27669260

Fiber Optic Bragg Grating Sensors for Thermographic Detection of Subsurface Anomalies

NASA Technical Reports Server (NTRS)

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

2009-01-01

Conventional thermography with an infrared imager has been shown to be an extremely viable technique for nondestructively detecting subsurface anomalies such as thickness variations due to corrosion. A recently developed technique using fiber optic sensors to measure temperature holds potential for performing similar inspections without requiring an infrared imager. The structure is heated using a heat source such as a quartz lamp with fiber Bragg grating (FBG) sensors at the surface of the structure to detect temperature. Investigated structures include a stainless steel plate with thickness variations simulated by small platelets attached to the back side using thermal grease. A relationship is shown between the FBG sensor thermal response and variations in material thickness. For comparison, finite element modeling was performed and found to agree closely with the fiber optic thermography results. This technique shows potential for applications where FBG sensors are already bonded to structures for Integrated Vehicle Health Monitoring (IVHM) strain measurements and can serve dual-use by also performing thermographic detection of subsurface anomalies.

Improvements of low-detection-limit filter-free fluorescence sensor developed by charge accumulation operation

NASA Astrophysics Data System (ADS)

Tanaka, Kiyotsugu; Choi, Yong Joon; Moriwaki, Yu; Hizawa, Takeshi; Iwata, Tatsuya; Dasai, Fumihiro; Kimura, Yasuyuki; Takahashi, Kazuhiro; Sawada, Kazuaki

2017-04-01

We developed a low-detection-limit filter-free fluorescence sensor by a charge accumulation technique. For charge accumulation, a floating diffusion amplifier (FDA), which included a floating diffusion capacitor, a transfer gate, and a source follower circuit, was used. To integrate CMOS circuits with the filter-free fluorescence sensor, we adopted a triple-well process to isolate transistors from the sensor on a single chip. We detected 0.1 nW fluorescence under the illumination of excitation light by 1.5 ms accumulation, which was one order of magnitude greater than that of a previous current detection sensor.

INNOVATIVE EASY-TO-USE PASSIVE TECHNIQUE FOR 222RN AND 220RN DECAY PRODUCT DETECTION.

PubMed

Mishra, Rosaline; Rout, R; Prajith, R; Jalalluddin, S; Sapra, B K; Mayya, Y S

2016-10-01

The decay products of radon and thoron are essentially the radioisotopes of polonium, bismuth and lead, and are solid particulates, which deposit in different parts of the respiratory tract upon inhalation, subsequently emitting high-energy alpha particles upon their radioactive decay. Development of passive deposition-based direct progeny sensors known as direct radon and thoron progeny sensors have provided an easy-to-use technique for time-integrated measurements of the decay products only. These dosemeters are apt for large-scale population dosimetry to assign inhalation doses to the public. The paper gives an insight into the technique, the calibration, comparison with the prevalently used active grab filter paper sampling technique, alpha track diameter analysis in these progeny sensors, progeny deposition velocity measurements carried out using these detector systems in the indoor as well as outdoor environment, and applications of these sensors for time-integrated unattached fraction estimation. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Microfabricated Nickel Based Sensors for Hostile and High Pressure Environments

NASA Astrophysics Data System (ADS)

Holt, Christopher Michael Bjustrom

This thesis outlines the development of two platforms for integrating microfabricated sensors with high pressure feedthroughs for application in hostile high temperature high pressure environments. An application in oil well production logging is explored and two sensors were implemented with these platforms for application in an oil well. The first platform developed involved microfabrication directly onto a cut and polished high pressure feedthrough. This technique enables a system that is more robust than the wire bonded silicon die technique used for MEMS integration in pressure sensors. Removing wire bonds from the traditional MEMS package allows for direct interface of a microfabricated sensor with a hostile high pressure fluid environment which is not currently possible. During the development of this platform key performance metrics included pressure testing to 70MPa and temperature cycling from 20°C to 200°C. This platform enables electronics integration with a variety of microfabricated electrical and thermal based sensors which can be immersed within the oil well environment. The second platform enabled free space fabrication of nickel microfabricated devices onto an array of pins using a thick tin sacrificial layer. This technique allowed microfabrication of metal MEMS that are released by distances of 1cm from their substrate. This method is quite flexible and allows for fabrication to be done on any pin array substrate regardless of surface quality. Being able to place released MEMS sensors directly onto traditional style circuit boards, ceramic circuit boards, electrical connectors, ribbon cables, pin headers, or high pressure feedthroughs greatly improves the variety of possible applications and reduces fabrication costs. These two platforms were then used to fabricate thermal conductivity sensors that showed excellent performance for distinguishing between oil, water, and gas phases. Testing was conducted at various flow rates and performance of the released platform was shown to be better than the performance seen in the anchored sensors while both platforms were significantly better than a simply fabricated wrapped wire sensor. The anchored platform was also used to demonstrate a traditional capacitance based fluid dielectric sensor which was found to work similarly to conventional commercial capacitance probes while being significantly smaller in size.

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.

Artifact Noise Removal Techniques on Seismocardiogram Using Two Tri-Axial Accelerometers

PubMed Central

Luu, Loc; Dinh, Anh

2018-01-01

The aim of this study is on the investigation of motion noise removal techniques using two-accelerometer sensor system and various placements of the sensors on gentle movement and walking of the patients. A Wi-Fi based data acquisition system and a framework on Matlab are developed to collect and process data while the subjects are in motion. The tests include eight volunteers who have no record of heart disease. The walking and running data on the subjects are analyzed to find the minimal-noise bandwidth of the SCG signal. This bandwidth is used to design filters in the motion noise removal techniques and peak signal detection. There are two main techniques of combining signals from the two sensors to mitigate the motion artifact: analog processing and digital processing. The analog processing comprises analog circuits performing adding or subtracting functions and bandpass filter to remove artifact noises before entering the data acquisition system. The digital processing processes all the data using combinations of total acceleration and z-axis only acceleration. The two techniques are tested on three placements of accelerometer sensors including horizontal, vertical, and diagonal on gentle motion and walking. In general, the total acceleration and z-axis acceleration are the best techniques to deal with gentle motion on all sensor placements which improve average systolic signal-noise-ratio (SNR) around 2 times and average diastolic SNR around 3 times comparing to traditional methods using only one accelerometer. With walking motion, ADDER and z-axis acceleration are the best techniques on all placements of the sensors on the body which enhance about 7 times of average systolic SNR and about 11 times of average diastolic SNR comparing to only one accelerometer method. Among the sensor placements, the performance of horizontal placement of the sensors is outstanding comparing with other positions on all motions. PMID:29614821

Ground Vibration Test Planning and Pre-Test Analysis for the X-33 Vehicle

NASA Technical Reports Server (NTRS)

Bedrossian, Herand; Tinker, Michael L.; Hidalgo, Homero

2000-01-01

This paper describes the results of the modal test planning and the pre-test analysis for the X-33 vehicle. The pre-test analysis included the selection of the target modes, selection of the sensor and shaker locations and the development of an accurate Test Analysis Model (TAM). For target mode selection, four techniques were considered, one based on the Modal Cost technique, one based on Balanced Singular Value technique, a technique known as the Root Sum Squared (RSS) method, and a Modal Kinetic Energy (MKE) approach. For selecting sensor locations, four techniques were also considered; one based on the Weighted Average Kinetic Energy (WAKE), one based on Guyan Reduction (GR), one emphasizing engineering judgment, and one based on an optimum sensor selection technique using Genetic Algorithm (GA) search technique combined with a criteria based on Hankel Singular Values (HSV's). For selecting shaker locations, four techniques were also considered; one based on the Weighted Average Driving Point Residue (WADPR), one based on engineering judgment and accessibility considerations, a frequency response method, and an optimum shaker location selection based on a GA search technique combined with a criteria based on HSV's. To evaluate the effectiveness of the proposed sensor and shaker locations for exciting the target modes, extensive numerical simulations were performed. Multivariate Mode Indicator Function (MMIF) was used to evaluate the effectiveness of each sensor & shaker set with respect to modal parameter identification. Several TAM reduction techniques were considered including, Guyan, IRS, Modal, and Hybrid. Based on a pre-test cross-orthogonality checks using various reduction techniques, a Hybrid TAM reduction technique was selected and was used for all three vehicle fuel level configurations.

Pressure-Sensor Assembly Technique

NASA Technical Reports Server (NTRS)

Pruzan, Daniel A.

2003-01-01

Nielsen Engineering & Research (NEAR) recently developed an ultrathin data acquisition system for use in turbomachinery testing at NASA Glenn Research Center. This system integrates a microelectromechanical- systems- (MEMS-) based absolute pressure sensor [0 to 50 psia (0 to 345 kPa)], temperature sensor, signal-conditioning application-specific integrated circuit (ASIC), microprocessor, and digital memory into a package which is roughly 2.8 in. (7.1 cm) long by 0.75 in. (1.9 cm) wide. Each of these components is flip-chip attached to a thin, flexible circuit board and subsequently ground and polished to achieve a total system thickness of 0.006 in. (0.15 mm). Because this instrument is so thin, it can be quickly adhered to any surface of interest where data can be collected without disrupting the flow being investigated. One issue in the development of the ultrathin data acquisition system was how to attach the MEMS pressure sensor to the circuit board in a manner which allowed the sensor s diaphragm to communicate with the ambient fluid while providing enough support for the chip to survive the grinding and polishing operations. The technique, developed by NEAR and Jabil Technology Services Group (San Jose, CA), is described below. In the approach developed, the sensor is attached to the specially designed circuit board, see Figure 1, using a modified flip-chip technique. The circular diaphragm on the left side of the sensor is used to actively measure the ambient pressure, while the diaphragm on the right is used to compensate for changes in output due to temperature variations. The circuit board is fabricated with an access hole through it so that when the completed system is installed onto a wind tunnel model (chip side down), the active diaphragm is exposed to the environment. After the sensor is flip-chip attached to the circuit board, the die is underfilled to support the chip during the subsequent grinding and polishing operations. To prevent this underfill material from getting onto the sensor s diaphragms, the circuit board is fabricated with two 25- micrometer-tall polymer rings, sized so that the diaphragms fit inside the rings once the chip is attached.

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.

Micro-patterning and characterization of PHEMA-co-PAM-based optical chemical sensors for lab-on-a-chip applications

PubMed Central

Zhu, Haixin; Zhou, Xianfeng; Su, Fengyu; Tian, Yanqing; Ashili, Shashanka; Holl, Mark R.; Meldrum, Deirdre R.

2012-01-01

We report a novel method for wafer level, high throughput optical chemical sensor patterning, with precise control of the sensor volume and capability of producing arbitrary microscale patterns. Monomeric oxygen (O2) and pH optical probes were polymerized with 2-hydroxyethyl methacrylate (HEMA) and acrylamide (AM) to form spin-coatable and further crosslinkable polymers. A micro-patterning method based on micro-fabrication techniques (photolithography, wet chemical process and reactive ion etch) was developed to miniaturize the sensor film onto glass substrates in arbitrary sizes and shapes. The sensitivity of fabricated micro-patterns was characterized under various oxygen concentrations and pH values. The process for spatially integration of two sensors (Oxygen and pH) on the same substrate surface was also developed, and preliminary fabrication and characterization results were presented. To the best of our knowledge, it is the first time that poly (2-hydroxylethyl methacrylate)-co-poly (acrylamide) (PHEMA-co-PAM)-based sensors had been patterned and integrated at the wafer level with micron scale precision control using microfabrication techniques. The developed methods can provide a feasible way to miniaturize and integrate the optical chemical sensor system and can be applied to any lab-on-a-chip system, especially the biological micro-systems requiring optical sensing of single or multiple analytes. PMID:23175599

Calibrating a novel multi-sensor physical activity measurement system.

PubMed

John, D; Liu, S; Sasaki, J E; Howe, C A; Staudenmayer, J; Gao, R X; Freedson, P S

2011-09-01

Advancing the field of physical activity (PA) monitoring requires the development of innovative multi-sensor measurement systems that are feasible in the free-living environment. The use of novel analytical techniques to combine and process these multiple sensor signals is equally important. This paper describes a novel multi-sensor 'integrated PA measurement system' (IMS), the lab-based methodology used to calibrate the IMS, techniques used to predict multiple variables from the sensor signals, and proposes design changes to improve the feasibility of deploying the IMS in the free-living environment. The IMS consists of hip and wrist acceleration sensors, two piezoelectric respiration sensors on the torso, and an ultraviolet radiation sensor to obtain contextual information (indoors versus outdoors) of PA. During lab-based calibration of the IMS, data were collected on participants performing a PA routine consisting of seven different ambulatory and free-living activities while wearing a portable metabolic unit (criterion measure) and the IMS. Data analyses on the first 50 adult participants are presented. These analyses were used to determine if the IMS can be used to predict the variables of interest. Finally, physical modifications for the IMS that could enhance the feasibility of free-living use are proposed and refinement of the prediction techniques is discussed.

High capacity fiber optic sensor networks using hybrid multiplexing techniques and their applications

NASA Astrophysics Data System (ADS)

Sun, Qizhen; Li, Xiaolei; Zhang, Manliang; Liu, Qi; Liu, Hai; Liu, Deming

2013-12-01

Fiber optic sensor network is the development trend of fiber senor technologies and industries. In this paper, I will discuss recent research progress on high capacity fiber sensor networks with hybrid multiplexing techniques and their applications in the fields of security monitoring, environment monitoring, Smart eHome, etc. Firstly, I will present the architecture of hybrid multiplexing sensor passive optical network (HSPON), and the key technologies for integrated access and intelligent management of massive fiber sensor units. Two typical hybrid WDM/TDM fiber sensor networks for perimeter intrusion monitor and cultural relics security are introduced. Secondly, we propose the concept of "Microstructure－Optical X Domin Refecltor (M-OXDR)" for fiber sensor network expansion. By fabricating smart micro-structures with the ability of multidimensional encoded and low insertion loss along the fiber, the fiber sensor network of simple structure and huge capacity more than one thousand could be achieved. Assisted by the WDM/TDM and WDM/FDM decoding methods respectively, we built the verification systems for long-haul and real-time temperature sensing. Finally, I will show the high capacity and flexible fiber sensor network with IPv6 protocol based hybrid fiber/wireless access. By developing the fiber optic sensor with embedded IPv6 protocol conversion module and IPv6 router, huge amounts of fiber optic sensor nodes can be uniquely addressed. Meanwhile, various sensing information could be integrated and accessed to the Next Generation Internet.

A hybrid artificial neural network as a software sensor for optimal control of a wastewater treatment process.

PubMed

Choi, D J; Park, H

2001-11-01

For control and automation of biological treatment processes, lack of reliable on-line sensors to measure water quality parameters is one of the most important problems to overcome. Many parameters cannot be measured directly with on-line sensors. The accuracy of existing hardware sensors is also not sufficient and maintenance problems such as electrode fouling often cause trouble. This paper deals with the development of software sensor techniques that estimate the target water quality parameter from other parameters using the correlation between water quality parameters. We focus our attention on the preprocessing of noisy data and the selection of the best model feasible to the situation. Problems of existing approaches are also discussed. We propose a hybrid neural network as a software sensor inferring wastewater quality parameter. Multivariate regression, artificial neural networks (ANN), and a hybrid technique that combines principal component analysis as a preprocessing stage are applied to data from industrial wastewater processes. The hybrid ANN technique shows an enhancement of prediction capability and reduces the overfitting problem of neural networks. The result shows that the hybrid ANN technique can be used to extract information from noisy data and to describe the nonlinearity of complex wastewater treatment processes.

Theory and Practice of Shear/Stress Strain Gage Hygrometry

NASA Technical Reports Server (NTRS)

Shams, Qamar A.; Fenner, Ralph L.

2006-01-01

Mechanical hygrometry has progressed during the last several decades from crude hygroscopes to state-of-the art strain-gage sensors. The strain-gage devices vary from different metallic beams to strain-gage sensors using cellulose crystallite elements, held in full shear restraint. This old technique is still in use but several companies are now actively pursuing development of MEMS miniaturized humidity sensors. These new sensors use polyimide thin film for water vapor adsorption and desorption. This paper will provide overview about modern humidity sensors.

Testing of a Microwave Blade Tip Clearance Sensor at the NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Woike, Mark R.; Roeder, James W.; Hughes, Christopher E.; Bencic, Timothy J.

2009-01-01

The development of new active tip clearance control and structural health monitoring schemes in turbine engines and other types of rotating machinery requires sensors that are highly accurate and can operate in a high-temperature environment. The use of a microwave sensor to acquire blade tip clearance and tip timing measurements is being explored at the NASA Glenn Research Center. The microwave blade tip clearance sensor works on principles that are very similar to a short-range radar system. The sensor sends a continuous microwave signal towards a target and measures the reflected signal. The phase difference of the reflected signal is directly proportional to the distance between the sensor and the target being measured. This type of sensor is beneficial in that it has the ability to operate at extremely high temperatures and is unaffected by contaminants that may be present in turbine engines. The use of microwave sensors for this application is a new concept. Techniques on calibrating the sensors along with installation effects are not well quantified as they are for other sensor technologies. Developing calibration techniques and evaluating installation effects are essential in using these sensors to make tip clearance and tip timing measurements. As a means of better understanding these issues, the microwave sensors were used on a benchtop calibration rig, a large axial vane fan, and a turbofan. Background on the microwave tip clearance sensor, an overview of their calibration, and the results from their use on the axial vane fan and the turbofan will be presented in this paper.

Testing of a Microwave Blade Tip Clearance Sensor at the NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Woike, Mark R.; Roeder, James W.; Hughes, Christopher E.; Bencic, Timothy J.

2009-01-01

The development of new active tip clearance control and structural health monitoring schemes in turbine engines and other types of rotating machinery requires sensors that are highly accurate and can operate in a high temperature environment. The use of a microwave sensor to acquire blade tip clearance and tip timing measurements is being explored at the NASA Glenn Research Center. The microwave blade tip clearance sensor works on principles that are very similar to a short range radar system. The sensor sends a continuous microwave signal towards a target and measures the reflected signal. The phase difference of the reflected signal is directly proportional to the distance between the sensor and the target being measured. This type of sensor is beneficial in that it has the ability to operate at extremely high temperatures and is unaffected by contaminants that may be present in turbine engines. The use of microwave sensors for this application is a new concept. Techniques on calibrating the sensors along with installation effects are not well quantified as they are for other sensor technologies. Developing calibration techniques and evaluating installation effects are essential in using these sensors to make tip clearance and tip timing measurements. As a means of better understanding these issues, the microwave sensors were used on a bench top calibration rig, a large axial vane fan, and a turbofan. Background on the microwave tip clearance sensor, an overview of their calibration, and the results from their use on the axial vane fan and the turbofan will be presented in this paper.

Electrochemical sensors and biosensors for the analysis of antineoplastic drugs.

PubMed

Lima, Handerson Rodrigues Silva; da Silva, Josany Saibrosa; de Oliveira Farias, Emanuel Airton; Teixeira, Paulo Ronaldo Sousa; Eiras, Carla; Nunes, Lívio César Cunha

2018-06-15

Cancer is a leading cause of death worldwide, often being treated with antineoplastic drugs that have high potential for toxicity to humans and the environment, even at very low concentrations. Therefore, monitoring these drugs is of utmost importance. Among the techniques used to detect substances at low concentrations, electrochemical sensors and biosensors have been noted for their practicality and low cost. This review brings, for the first time, a simplified outline of the main electrochemical sensors and biosensors developed for the analysis of antineoplastic drugs. The drugs analyzed and the methodology used for electrochemical sensing are described, as are the techniques used for drug quantification and the analytical performance of each sensor, highlighting the limit of detection (LOD), as well as the linear range of quantification (LR) for each system. Finally, we present a technological prospection on the development and use of electrochemical sensors and biosensors in the quantification of antineoplastic drugs. A search of international patent databases revealed no patents currently submitted under this topic, suggesting this is an area to be further explored. We also show that the use of these systems has been gaining prominence in recent years, and that the quantification of antineoplastic drugs using electrochemical techniques could bring great financial and health benefits. Copyright © 2018. Published by Elsevier B.V.

Recent development of electrochemiluminescence sensors for food analysis.

PubMed

Hao, Nan; Wang, Kun

2016-10-01

Food quality and safety are closely related to human health. In the face of unceasing food safety incidents, various analytical techniques, such as mass spectrometry, chromatography, spectroscopy, and electrochemistry, have been applied in food analysis. High sensitivity usually requires expensive instruments and complicated procedures. Although these modern analytical techniques are sensitive enough to ensure food safety, sometimes their applications are limited because of the cost, usability, and speed of analysis. Electrochemiluminescence (ECL) is a powerful analytical technique that is attracting more and more attention because of its outstanding performance. In this review, the mechanisms of ECL and common ECL luminophores are briefly introduced. Then an overall review of the principles and applications of ECL sensors for food analysis is provided. ECL can be flexibly combined with various separation techniques. Novel materials (e.g., various nanomaterials) and strategies (e.g., immunoassay, aptasensors, and microfluidics) have been progressively introduced into the design of ECL sensors. By illustrating some selected representative works, we summarize the state of the art in the development of ECL sensors for toxins, heavy metals, pesticides, residual drugs, illegal additives, viruses, and bacterias. Compared with other methods, ECL can provide rapid, low-cost, and sensitive detection for various food contaminants in complex matrixes. However, there are also some limitations and challenges. Improvements suited to the characteristics of food analysis are still necessary.

Fiber Fabry-Perot interferometer sensor for measuring resonances of piezoelectric elements

NASA Astrophysics Data System (ADS)

da Silva, Ricardo E.; Oliveira, Roberson A.; Pohl, Alexandre A. P.

2011-05-01

The development of a fiber extrinsic Fabry-Perot interferometer for measuring vibration amplitude and resonances of piezoelectric elements is reported. The signal demodulation method based on the use of an optical spectrum analyzer allows the measurement of displacements and resonances with high resolution. The technique consists basically in monitoring changes in the intensity or the wavelength of a single interferometric fringe at a point of high sensitivity in the sensor response curve. For sensor calibration, three signal processing techniques were employed. Vibration amplitude measurement with 0.84 nm/V sensitivity and the characterization of the piezo resonance is demonstrated.

Range estimation techniques in single-station thunderstorm warning sensors based upon gated, wideband, magnetic direction finder technology

NASA Technical Reports Server (NTRS)

Pifer, Alburt E.; Hiscox, William L.; Cummins, Kenneth L.; Neumann, William T.

1991-01-01

Gated, wideband, magnetic direction finders (DFs) were originally designed to measure the bearing of cloud-to-ground lightning relative to the sensor. A recent addition to this device uses proprietary waveform discrimination logic to select return stroke signatures and certain range dependent features in the waveform to provide an estimate of range of flashes within 50 kms. The enhanced ranging techniques are discussed which were designed and developed for use in single station thunderstorm warning sensor. Included are the results of on-going evaluations being conducted under a variety of meteorological and geographic conditions.

Advances in Bio-Tactile Sensors for Minimally Invasive Surgery Using the Fibre Bragg Grating Force Sensor Technique:A Survey

PubMed Central

Abushagur, Abdulfatah A.G.; Arsad, Norhana; Ibne Reaz, Mamun; Ashrif, A.; Bakar, A.

2014-01-01

The large interest in utilising fibre Bragg grating (FBG) strain sensors for minimally invasive surgery (MIS) applications to replace conventional electrical tactile sensors has grown in the past few years. FBG strain sensors offer the advantages of optical fibre sensors, such as high sensitivity, immunity to electromagnetic noise, electrical passivity and chemical inertness, but are not limited by phase discontinuity or intensity fluctuations. FBG sensors feature a wavelength-encoding sensing signal that enables distributed sensing that utilises fewer connections. In addition, their flexibility and lightness allow easy insertion into needles and catheters, thus enabling localised measurements inside tissues and blood. Two types of FBG tactile sensors have been emphasised in the literature: single-point and array FBG tactile sensors. This paper describes the current design, development and research of the optical fibre tactile techniques that are based on FBGs to enhance the performance of MIS procedures in general. Providing MIS or microsurgery surgeons with accurate and precise measurements and control of the contact forces during tissues manipulation will benefit both surgeons and patients. PMID:24721774

Development of paper-based electrochemical sensors for water quality monitoring

NASA Astrophysics Data System (ADS)

Smith, Suzanne; Bezuidenhout, Petroné; Mbanjwa, Mesuli; Zheng, Haitao; Conning, Mariette; Palaniyandy, Nithyadharseni; Ozoemena, Kenneth; Land, Kevin

2016-02-01

We present a method for the development of paper-based electrochemical sensors for detection of heavy metals in water samples. Contaminated water leads to serious health problems and environmental issues. Paper is ideally suited for point-of-care testing, as it is low cost, disposable, and multi-functional. Initial sensor designs were manufactured on paper substrates using combinations of inkjet printing and screen printing technologies using silver and carbon inks. Bismuth onion-like carbon nanoparticle ink was manufactured and used as the active material of the sensor for both commercial and paper-based sensors, which were compared using standard electrochemical analysis techniques. The results highlight the potential of paper-based sensors to be used effectively for rapid water quality monitoring at the point-of-need.

Nanophotonic Image Sensors

PubMed Central

Hu, Xin; Wen, Long; Yu, Yan; Cumming, David R. S.

2016-01-01

The increasing miniaturization and resolution of image sensors bring challenges to conventional optical elements such as spectral filters and polarizers, the properties of which are determined mainly by the materials used, including dye polymers. Recent developments in spectral filtering and optical manipulating techniques based on nanophotonics have opened up the possibility of an alternative method to control light spectrally and spatially. By integrating these technologies into image sensors, it will become possible to achieve high compactness, improved process compatibility, robust stability and tunable functionality. In this Review, recent representative achievements on nanophotonic image sensors are presented and analyzed including image sensors with nanophotonic color filters and polarizers, metamaterial‐based THz image sensors, filter‐free nanowire image sensors and nanostructured‐based multispectral image sensors. This novel combination of cutting edge photonics research and well‐developed commercial products may not only lead to an important application of nanophotonics but also offer great potential for next generation image sensors beyond Moore's Law expectations. PMID:27239941

Noncontact techniques for diesel engine diagnostics using exhaust waveform analysis

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

Gore, D.A.; Cooke, G.J.

1987-01-01

RCA Corporation's continuing efforts to develop noncontact test techniques for diesel engines have led to recent advancements in deep engine diagnostics. The U.S. Army Tank-Automotive Command (TACOM) has been working with RCA for the development of new noncontact sensors and test techniques which use these sensors in conjunction with their family of Simplified Test Equipment (STE) to perform vehicle diagnostics. The STE systems are microprocessor-based maintenance tools that assist the Army mechanic in diagnosing malfunctions in both tactical and combat vehicles. The test systems support the mechanic by providing the sophisticated signal processing capabilities necessary for a wide range ofmore » diagnostic testing including exhaust waveform analysis.« less

The development of sensors and techniques for in situ water quality monitoring

NASA Technical Reports Server (NTRS)

Liu, C. C.

1976-01-01

Enzyme electrodes and chloride ion electrodes were investigated for in situ monitoring of water quality. Preliminary results show that miniature chloride ion electrodes and a phenol sensor are most promising in determining trace contaminants in water.

Sensor development for in situ detection of concentration polarization and fouling of reverse osmosis membranes

NASA Astrophysics Data System (ADS)

Detrich, Kahlil T.; Goulbourne, Nakhiah C.

2009-03-01

The purpose of this research is to evaluate three polymer electroding techniques in developing a novel in situ sensor for an RO system using the electrical response of a thin film composite sensor. Electrical impedance spectroscopy (EIS) was used to measure the sensor response when exposed to sodium chloride solutions with concentrations from 0.1 M to 0.8 M in both single and double bath configurations. An insulated carbon grease sensor was mechanically stable while a composite Direct Assembly Process (DAP) sensor was fragile upon hydration. Scanning electron microscopy results from an impregnation-reduction technique showed gold nanoparticles were deposited most effectively when presoaked in a potassium hydroxide solution and on an uncoated membrane; surface resistances remained too high for sensor implementation. Through thickness carbon grease sensors showed a transient response to changes in concentration, and no meaningful concentration sensitivity was noted for the time scales over which EIS measurements were taken. Surface carbon grease electrodes attached to the polyamide thin film were not sensitive to concentration. The impedance spectra indicated the carbon grease sensor was unable to detect changes in concentration in double bath experiments when implemented with the polyamide surface exposed to salt solutions. DAP sensors lacked a consistent response to changes in concentration too. A reverse double bath experiment with the polysulfone layer exposed to a constant concentration exhibited a transient impedance response similar to through thickness carbon grease sensors in a single bath at constant concentration. These results suggest that the microporous polysulfone layer is responsible for sensor response to concentration.

Performance Analysis of Receive Diversity in Wireless Sensor Networks over GBSBE Models

PubMed Central

Goel, Shivali; Abawajy, Jemal H.; Kim, Tai-hoon

2010-01-01

Wireless sensor networks have attracted a lot of attention recently. In this paper, we develop a channel model based on the elliptical model for multipath components involving randomly placed scatterers in the scattering region with sensors deployed on a field. We verify that in a sensor network, the use of receive diversity techniques improves the performance of the system. Extensive performance analysis of the system is carried out for both single and multiple antennas with the applied receive diversity techniques. Performance analyses based on variations in receiver height, maximum multipath delay and transmit power have been performed considering different numbers of antenna elements present in the receiver array, Our results show that increasing the number of antenna elements for a wireless sensor network does indeed improve the BER rates that can be obtained. PMID:22163510

Recent Development in Optical Chemical Sensors Coupling with Flow Injection Analysis

PubMed Central

Ojeda, Catalina Bosch; Rojas, Fuensanta Sánchez

2006-01-01

Optical techniques for chemical analysis are well established and sensors based on these techniques are now attracting considerable attention because of their importance in applications such as environmental monitoring, biomedical sensing, and industrial process control. On the other hand, flow injection analysis (FIA) is advisable for the rapid analysis of microliter volume samples and can be interfaced directly to the chemical process. The FIA has become a widespread automatic analytical method for more reasons; mainly due to the simplicity and low cost of the setups, their versatility, and ease of assembling. In this paper, an overview of flow injection determinations by using optical chemical sensors is provided, and instrumentation, sensor design, and applications are discussed. This work summarizes the most relevant manuscripts from 1980 to date referred to analysis using optical chemical sensors in FIA.

Micromachined lab-on-a-tube sensors for simultaneous brain temperature and cerebral blood flow measurements.

PubMed

Li, Chunyan; Wu, Pei-Ming; Hartings, Jed A; Wu, Zhizhen; Cheyuo, Cletus; Wang, Ping; LeDoux, David; Shutter, Lori A; Ramaswamy, Bharat Ram; Ahn, Chong H; Narayan, Raj K

2012-08-01

This work describes the development of a micromachined lab-on-a-tube device for simultaneous measurement of brain temperature and regional cerebral blood flow. The device consists of two micromachined gold resistance temperature detectors with a 4-wire configuration. One is used as a temperature sensor and the other as a flow sensor. The temperature sensor operates with AC excitation current of 500 μA and updates its outputs at a rate of 5 Hz. The flow sensor employs a periodic heating and cooling technique under constant-temperature mode and updates its outputs at a rate of 0.1 Hz. The temperature sensor is also used to compensate for temperature changes during the heating period of the flow sensor to improve the accuracy of flow measurements. To prevent thermal and electronic crosstalk between the sensors, the temperature sensor is located outside the "thermal influence" region of the flow sensor and the sensors are separated into two different layers with a thin-film Copper shield. We evaluated the sensors for accuracy, crosstalk and long-term drift in human blood-stained cerebrospinal fluid. These in vitro experiments showed that simultaneous temperature and flow measurements with a single lab-on-a-tube device are accurate and reliable over the course of 5 days. It has a resolution of 0.013 °C and 0.18 ml/100 g/min; and achieves an accuracy of 0.1 °C and 5 ml/100 g/min for temperature and flow sensors respectively. The prototype device and techniques developed here establish a foundation for a multi-sensor lab-on-a-tube, enabling versatile multimodality monitoring applications.

Chemical Sensor Platform for Non-Invasive Monitoring of Activity and Dehydration

PubMed Central

Solovei, Dmitry; Žák, Jaromír; Majzlíková, Petra; Sedláček, Jiří; Hubálek, Jaromír

2015-01-01

A non-invasive solution for monitoring of the activity and dehydration of organisms is proposed in the work. For this purpose, a wireless standalone chemical sensor platform using two separate measurement techniques has been developed. The first approach for activity monitoring is based on humidity measurement. Our solution uses new humidity sensor based on a nanostructured TiO2 surface for sweat rate monitoring. The second technique is based on monitoring of potassium concentration in urine. High level of potassium concentration denotes clear occurrence of dehydration. Furthermore, a Wireless Body Area Network (WBAN) was developed for this sensor platform to manage data transfer among devices and the internet. The WBAN coordinator controls the sensor devices and collects and stores the measured data. The collected data is particular to individuals and can be shared with physicians, emergency systems or athletes' coaches. Long-time monitoring of activity and potassium concentration in urine can help maintain the appropriate water intake of elderly people or athletes and to send warning signals in the case of near dehydration. The created sensor system was calibrated and tested in laboratory and real conditions as well. The measurement results are discussed. PMID:25594591

Development and testing of an electrochemical methane sensor

DOE PAGES

Sekhar, Praveen K.; Kysar, Jesse; Brosha, Eric Lanich; ...

2016-01-12

In this article, the development of an electrochemical methane sensor is presented. The mixed potential based sensor is based on tin doped indium oxide (ITO) and platinum electrodes and yttria-stabilized zirconia (YSZ) electrolyte. The sensor was fabricated using the inexpensive tape-cast method. The sensor responded to methane with a response time of 15 s. The staircase response to methane indicated a 44 mV sensor response to 100 ppm of methane. The sensor response indicated a log-linear relationship with the methane concentration. Upon 500 h of sensor testing, a 5% reduction in methane sensitivity was observed. The cross-sensitivity study on themore » sensor indicated minimal interference to NO, NO 2, and CO 2. To improve the sensitivity to methane, a signal conditioning method referred to as the pulsed discharge technique (PDT) was applied. Finally, a fourfold increase in methane sensitivity was observed when the sensor was subjected to PDT. Future studies include the miniaturization of the sensor with integrated heater design.« less

Development and testing of an electrochemical methane sensor

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

Sekhar, Praveen K.; Kysar, Jesse; Brosha, Eric Lanich

In this article, the development of an electrochemical methane sensor is presented. The mixed potential based sensor is based on tin doped indium oxide (ITO) and platinum electrodes and yttria-stabilized zirconia (YSZ) electrolyte. The sensor was fabricated using the inexpensive tape-cast method. The sensor responded to methane with a response time of 15 s. The staircase response to methane indicated a 44 mV sensor response to 100 ppm of methane. The sensor response indicated a log-linear relationship with the methane concentration. Upon 500 h of sensor testing, a 5% reduction in methane sensitivity was observed. The cross-sensitivity study on themore » sensor indicated minimal interference to NO, NO 2, and CO 2. To improve the sensitivity to methane, a signal conditioning method referred to as the pulsed discharge technique (PDT) was applied. Finally, a fourfold increase in methane sensitivity was observed when the sensor was subjected to PDT. Future studies include the miniaturization of the sensor with integrated heater design.« less

Dynamic response of tapered optical multimode fiber coated with carbon nanotubes for ethanol sensing application.

PubMed

Shabaneh, Arafat; Girei, Saad; Arasu, Punitha; Mahdi, Mohd; Rashid, Suraya; Paiman, Suriati; Yaacob, Mohd

2015-05-04

Ethanol is a highly combustible chemical universally designed for biomedical applications. In this paper, optical sensing performance of tapered multimode fiber tip coated with carbon nanotube (CNT) thin film towards aqueous ethanol with different concentrations is investigated. The tapered optical multimode fiber tip is coated with CNT using drop-casting technique and is annealed at 70 °C to enhance the binding of the nanomaterial to the silica fiber tip. The optical fiber tip and the CNT sensing layer are micro-characterized using FESEM and Raman spectroscopy techniques. When the developed sensor was exposed to different concentrations of ethanol (5% to 80%), the sensor reflectance reduced proportionally. The developed sensors showed high sensitivity, repeatability and fast responses (<55 s) towards ethanol.

Dynamic Response of Tapered Optical Multimode Fiber Coated with Carbon Nanotubes for Ethanol Sensing Application

PubMed Central

Shabaneh, Arafat; Girei, Saad; Arasu, Punitha; Mahdi, Mohd; Rashid, Suraya; Paiman, Suriati; Yaacob, Mohd

2015-01-01

Ethanol is a highly combustible chemical universally designed for biomedical applications. In this paper, optical sensing performance of tapered multimode fiber tip coated with carbon nanotube (CNT) thin film towards aqueous ethanol with different concentrations is investigated. The tapered optical multimode fiber tip is coated with CNT using drop-casting technique and is annealed at 70 °C to enhance the binding of the nanomaterial to the silica fiber tip. The optical fiber tip and the CNT sensing layer are micro-characterized using FESEM and Raman spectroscopy techniques. When the developed sensor was exposed to different concentrations of ethanol (5% to 80%), the sensor reflectance reduced proportionally. The developed sensors showed high sensitivity, repeatability and fast responses (<55 s) towards ethanol. PMID:25946634

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

Embedded fiber optic sensors for monitoring processing, quality and structural health of resin transfer molded components

NASA Astrophysics Data System (ADS)

Keulen, C.; Rocha, B.; Yildiz, M.; Suleman, A.

2011-07-01

Due to their small size and flexibility fiber optics can be embedded into composite materials with little negative effect on strength and reliability of the host material. Fiber optic sensors such as Fiber Bragg Gratings (FBG) or Etched Fiber Sensors (EFS) can be used to detect a number of relevant parameters such as flow, degree of cure, quality and structural health throughout the life of a composite component. With a detection algorithm these embedded sensors can be used to detect damage in real time while the component remains in service. This paper presents the research being conducted on the use of fiber optic sensors for process and Structural Health Monitoring (SHM) of Resin Transfer Molded (RTM) composite structures. Fiber optic sensors are used at all life stages of an RTM composite panel. A laboratory scale RTM apparatus was developed with the capability of visually monitoring the resin filling process. A technique for embedding fiber optic sensors with this apparatus has also been developed. Both FBGs and EFSs have been embedded in composite panels using the apparatus. EFSs to monitor the fabrication process, specifically resin flow have been embedded and shown to be capable of detecting the presence of resin at various locations as it is injected into the mold. Simultaneously these sensors were multiplexed on the same fiber with FBGs, which have the ability to measure strain. Since multiple sensors can be multiplexed on a single fiber the number of ingress/egress locations required per sensor can be significantly reduced. To characterize the FBGs for strain detection tensile test specimens with embedded FBG sensors have been produced. These specimens have been instrumented with a resistive strain gauge for benchmarking. Both specimens and embedded sensors were characterized through tensile testing. Furthermore FBGs have been embedded into composite panels in a manner that is conducive to detection of Lamb waves generated with a centrally located PZT. To sense Lamb waves a high speed, high precision sensing technique is required to acquire data from embedded FBGs due to the high velocities and small strain amplitudes of these guided waves. A technique based on a filter consisting of a tunable FBG was developed. Since this filter is not dependant on moving parts, tests executed with this filter concluded with the detection of Lamb waves, removing the influence of temperature and operational strains. A damage detection algorithm was developed to detect and localize cracks and delaminations.

Design Principles for Rapid Prototyping Forces Sensors using 3D Printing.

PubMed

Kesner, Samuel B; Howe, Robert D

2011-07-21

Force sensors provide critical information for robot manipulators, manufacturing processes, and haptic interfaces. Commercial force sensors, however, are generally not adapted to specific system requirements, resulting in sensors with excess size, cost, and fragility. To overcome these issues, 3D printers can be used to create components for the quick and inexpensive development of force sensors. Limitations of this rapid prototyping technology, however, require specialized design principles. In this paper, we discuss techniques for rapidly developing simple force sensors, including selecting and attaching metal flexures, using inexpensive and simple displacement transducers, and 3D printing features to aid in assembly. These design methods are illustrated through the design and fabrication of a miniature force sensor for the tip of a robotic catheter system. The resulting force sensor prototype can measure forces with an accuracy of as low as 2% of the 10 N measurement range.

Thin film sensor materials for detection of Nitro-Aromatic explosives

NASA Astrophysics Data System (ADS)

Ramdasi, Dipali; Mudhalwadkar, Rohini

2018-03-01

Many countries have experienced terrorist activities and innocent people have suffered. Timely detection of explosives can avoid this situation. This paper targets the detection of Nitrobenzene and Nitrotoluene, which are nitroaromatic compounds possessing explosive properties. As direct sensors for detecting these compounds are not available, Polyaniline based thin film sensors doped with palladium are developed using the spin coating technique. The response of the developed sensors is observed for varying concentrations of explosives. It is observed that zinc oxide based sensor is more sensitive to Nitrotoluene exhibiting a relative change in resistance of 0.78. The tungsten oxide sensor is more sensitive to Nitrobenzene with a relative change in resistance of 0.48. The sensor performance is assessed by measuring the response and recovery time. The cross sensitivity of the sensors is evaluated for ethanol, acetone and methanol which was observed as very low.

The Need for a Shear Stress Calibration Standard

NASA Technical Reports Server (NTRS)

Scott, Michael A.

2004-01-01

By surveying current research of various micro-electro mechanical systems (MEMS) shear stress sensor development efforts we illustrate the wide variety of methods used to test and characterize these sensors. The different methods of testing these sensors make comparison of results difficult in some cases, and also this comparison is further complicated by the different formats used in reporting the results of these tests. The fact that making these comparisons can be so difficult at times clearly illustrates a need for standardized testing and reporting methodologies. This need indicates that the development of a national or international standard for the calibration of MEMS shear stress sensors should be undertaken. As a first step towards the development of this standard, two types of devices are compared and contrasted. The first type device is a laminar flow channel with two different versions considered: the first built with standard manufacturing techniques and the second with advanced precision manufacturing techniques. The second type of device is a new concept for creating a known shear stress consisting of a rotating wheel with the sensor mounted tangentially to the rim and positioned in close proximity to the rim. The shear stress generated by the flow at the sensor position is simply tau = (mu)r(omega)/h, where mu is the viscosity of the ambient gas, r the wheel radius, omega the angular velocity of the wheel, and h the width of the gap between the wheel rim and the sensor. Additionally, issues related to the development of a standard for shear stress calibration are identified and discussed.

Biology Inspired Approach for Communal Behavior in Sensor Networks

NASA Technical Reports Server (NTRS)

Jones, Kennie H.; Lodding, Kenneth N.; Olariu, Stephan; Wilson, Larry; Xin, Chunsheng

2006-01-01

Research in wireless sensor network technology has exploded in the last decade. Promises of complex and ubiquitous control of the physical environment by these networks open avenues for new kinds of science and business. Due to the small size and low cost of sensor devices, visionaries promise systems enabled by deployment of massive numbers of sensors working in concert. Although the reduction in size has been phenomenal it results in severe limitations on the computing, communicating, and power capabilities of these devices. Under these constraints, research efforts have concentrated on developing techniques for performing relatively simple tasks with minimal energy expense assuming some form of centralized control. Unfortunately, centralized control does not scale to massive size networks and execution of simple tasks in sparsely populated networks will not lead to the sophisticated applications predicted. These must be enabled by new techniques dependent on local and autonomous cooperation between sensors to effect global functions. As a step in that direction, in this work we detail a technique whereby a large population of sensors can attain a global goal using only local information and by making only local decisions without any form of centralized control.

Study of optical techniques for the Ames unitary wind tunnels. Part 3: Angle of attack

NASA Technical Reports Server (NTRS)

Lee, George

1992-01-01

A review of optical sensors that are capable of accurate angle of attack measurements in wind tunnels was conducted. These include sensors being used or being developed at NASA Ames and Langley Research Centers, Boeing Airplane Company, McDonald Aircraft Company, Arnold Engineering Development Center, National Aerospace Laboratory of the Netherlands, National Research Council of Canada, and the Royal Aircraft Establishment of England. Some commercial sensors that may be applicable to accurate angle measurements were also reviewed. It was found that the optical sensor systems were based on interferometers, polarized light detector, linear or area photodiode cameras, position sensing photodetectors, and laser scanners. Several of the optical sensors can meet the requirements of the Ames Unitary Plan Wind Tunnel. Two of these, the Boeing interferometer and the Complere lateral effect photodiode sensors are being developed for the Ames Unitary Plan Wind Tunnel.

Probabilistic Multi-Sensor Fusion Based Indoor Positioning System on a Mobile Device

PubMed Central

He, Xiang; Aloi, Daniel N.; Li, Jia

2015-01-01

Nowadays, smart mobile devices include more and more sensors on board, such as motion sensors (accelerometer, gyroscope, magnetometer), wireless signal strength indicators (WiFi, Bluetooth, Zigbee), and visual sensors (LiDAR, camera). People have developed various indoor positioning techniques based on these sensors. In this paper, the probabilistic fusion of multiple sensors is investigated in a hidden Markov model (HMM) framework for mobile-device user-positioning. We propose a graph structure to store the model constructed by multiple sensors during the offline training phase, and a multimodal particle filter to seamlessly fuse the information during the online tracking phase. Based on our algorithm, we develop an indoor positioning system on the iOS platform. The experiments carried out in a typical indoor environment have shown promising results for our proposed algorithm and system design. PMID:26694387

Probabilistic Multi-Sensor Fusion Based Indoor Positioning System on a Mobile Device.

PubMed

He, Xiang; Aloi, Daniel N; Li, Jia

2015-12-14

Nowadays, smart mobile devices include more and more sensors on board, such as motion sensors (accelerometer, gyroscope, magnetometer), wireless signal strength indicators (WiFi, Bluetooth, Zigbee), and visual sensors (LiDAR, camera). People have developed various indoor positioning techniques based on these sensors. In this paper, the probabilistic fusion of multiple sensors is investigated in a hidden Markov model (HMM) framework for mobile-device user-positioning. We propose a graph structure to store the model constructed by multiple sensors during the offline training phase, and a multimodal particle filter to seamlessly fuse the information during the online tracking phase. Based on our algorithm, we develop an indoor positioning system on the iOS platform. The experiments carried out in a typical indoor environment have shown promising results for our proposed algorithm and system design.

Smart sensor systems for human health breath monitoring applications.

PubMed

Hunter, G W; Xu, J C; Biaggi-Labiosa, A M; Laskowski, D; Dutta, P K; Mondal, S P; Ward, B J; Makel, D B; Liu, C C; Chang, C W; Dweik, R A

2011-09-01

Breath analysis techniques offer a potential revolution in health care diagnostics, especially if these techniques can be brought into standard use in the clinic and at home. The advent of microsensors combined with smart sensor system technology enables a new generation of sensor systems with significantly enhanced capabilities and minimal size, weight and power consumption. This paper discusses the microsensor/smart sensor system approach and provides a summary of efforts to migrate this technology into human health breath monitoring applications. First, the basic capability of this approach to measure exhaled breath associated with exercise physiology is demonstrated. Building from this foundation, the development of a system for a portable asthma home health care system is described. A solid-state nitric oxide (NO) sensor for asthma monitoring has been identified, and efforts are underway to miniaturize this NO sensor technology and integrate it into a smart sensor system. It is concluded that base platform microsensor technology combined with smart sensor systems can address the needs of a range of breath monitoring applications and enable new capabilities for healthcare.

Beamforming array techniques for acoustic emission monitoring of large concrete structures

NASA Astrophysics Data System (ADS)

McLaskey, Gregory C.; Glaser, Steven D.; Grosse, Christian U.

2010-06-01

This paper introduces a novel method of acoustic emission (AE) analysis which is particularly suited for field applications on large plate-like reinforced concrete structures, such as walls and bridge decks. Similar to phased-array signal processing techniques developed for other non-destructive evaluation methods, this technique adapts beamforming tools developed for passive sonar and seismological applications for use in AE source localization and signal discrimination analyses. Instead of relying on the relatively weak P-wave, this method uses the energy-rich Rayleigh wave and requires only a small array of 4-8 sensors. Tests on an in-service reinforced concrete structure demonstrate that the azimuth of an artificial AE source can be determined via this method for sources located up to 3.8 m from the sensor array, even when the P-wave is undetectable. The beamforming array geometry also allows additional signal processing tools to be implemented, such as the VESPA process (VElocity SPectral Analysis), whereby the arrivals of different wave phases are identified by their apparent velocity of propagation. Beamforming AE can reduce sampling rate and time synchronization requirements between spatially distant sensors which in turn facilitates the use of wireless sensor networks for this application.

Giant Magnetoresistance Sensors: A Review on Structures and Non-Destructive Eddy Current Testing Applications

PubMed Central

Rifai, Damhuji; Abdalla, Ahmed N.; Ali, Kharudin; Razali, Ramdan

2016-01-01

Non-destructive eddy current testing (ECT) is widely used to examine structural defects in ferromagnetic pipe in the oil and gas industry. Implementation of giant magnetoresistance (GMR) sensors as magnetic field sensors to detect the changes of magnetic field continuity have increased the sensitivity of eddy current techniques in detecting the material defect profile. However, not many researchers have described in detail the structure and issues of GMR sensors and their application in eddy current techniques for nondestructive testing. This paper will describe the implementation of GMR sensors in non-destructive testing eddy current testing. The first part of this paper will describe the structure and principles of GMR sensors. The second part outlines the principles and types of eddy current testing probe that have been studied and developed by previous researchers. The influence of various parameters on the GMR measurement and a factor affecting in eddy current testing will be described in detail in the third part of this paper. Finally, this paper will discuss the limitations of coil probe and compensation techniques that researchers have applied in eddy current testing probes. A comprehensive review of previous studies on the application of GMR sensors in non-destructive eddy current testing also be given at the end of this paper. PMID:26927123

Giant Magnetoresistance Sensors: A Review on Structures and Non-Destructive Eddy Current Testing Applications.

PubMed

Rifai, Damhuji; Abdalla, Ahmed N; Ali, Kharudin; Razali, Ramdan

2016-02-26

Non-destructive eddy current testing (ECT) is widely used to examine structural defects in ferromagnetic pipe in the oil and gas industry. Implementation of giant magnetoresistance (GMR) sensors as magnetic field sensors to detect the changes of magnetic field continuity have increased the sensitivity of eddy current techniques in detecting the material defect profile. However, not many researchers have described in detail the structure and issues of GMR sensors and their application in eddy current techniques for nondestructive testing. This paper will describe the implementation of GMR sensors in non-destructive testing eddy current testing. The first part of this paper will describe the structure and principles of GMR sensors. The second part outlines the principles and types of eddy current testing probe that have been studied and developed by previous researchers. The influence of various parameters on the GMR measurement and a factor affecting in eddy current testing will be described in detail in the third part of this paper. Finally, this paper will discuss the limitations of coil probe and compensation techniques that researchers have applied in eddy current testing probes. A comprehensive review of previous studies on the application of GMR sensors in non-destructive eddy current testing also be given at the end of this paper.

Modelling the Energy Efficient Sensor Nodes for Wireless Sensor Networks

NASA Astrophysics Data System (ADS)

Dahiya, R.; Arora, A. K.; Singh, V. R.

2015-09-01

Energy is an important requirement of wireless sensor networks for better performance. A widely employed energy-saving technique is to place nodes in sleep mode, corresponding to low-power consumption as well as to reduce operational capabilities. In this paper, Markov model of a sensor network is developed. The node is considered to enter a sleep mode. This model is used to investigate the system performance in terms of energy consumption, network capacity and data delivery delay.

A review of recent advances in optical fibre sensors for in vivo dosimetry during radiotherapy

PubMed Central

O'Keeffe, S; McCarthy, D; Woulfe, P; Grattan, M W D; Hounsell, A R; Sporea, D; Mihai, L; Vata, I; Leen, G

2015-01-01

This article presents an overview of the recent developments and requirements in radiotherapy dosimetry, with particular emphasis on the development of optical fibre dosemeters for radiotherapy applications, focusing particularly on in vivo applications. Optical fibres offer considerable advantages over conventional techniques for radiotherapy dosimetry, owing to their small size, immunity to electromagnetic interferences, and suitability for remote monitoring and multiplexing. The small dimensions of optical fibre-based dosemeters, together with being lightweight and flexible, mean that they are minimally invasive and thus particularly suited to in vivo dosimetry. This means that the sensor can be placed directly inside a patient, for example, for brachytherapy treatments, the optical fibres could be placed in the tumour itself or into nearby critical tissues requiring monitoring, via the same applicators or needles used for the treatment delivery thereby providing real-time dosimetric information. The article outlines the principal sensor design systems along with some of the main strengths and weaknesses associated with the development of these techniques. The successful demonstration of these sensors in a range of different clinical environments is also presented. PMID:25761212

The AOLI low-order non-linear curvature wavefront sensor: laboratory and on-sky results

NASA Astrophysics Data System (ADS)

Crass, Jonathan; King, David; MacKay, Craig

2014-08-01

Many adaptive optics (AO) systems in use today require the use of bright reference objects to determine the effects of atmospheric distortions. Typically these systems use Shack-Hartmann Wavefront sensors (SHWFS) to distribute incoming light from a reference object between a large number of sub-apertures. Guyon et al. evaluated the sensitivity of several different wavefront sensing techniques and proposed the non-linear Curvature Wavefront Sensor (nlCWFS) offering improved sensitivity across a range of orders of distortion. On large ground-based telescopes this can provide nearly 100% sky coverage using natural guide stars. We present work being undertaken on the nlCWFS development for the Adaptive Optics Lucky Imager (AOLI) project. The wavefront sensor is being developed as part of a low-order adaptive optics system for use in a dedicated instrument providing an AO corrected beam to a Lucky Imaging based science detector. The nlCWFS provides a total of four reference images on two photon-counting EMCCDs for use in the wavefront reconstruction process. We present results from both laboratory work using a calibration system and the first on-sky data obtained with the nlCWFS at the 4.2 metre William Herschel Telescope, La Palma. In addition, we describe the updated optical design of the wavefront sensor, strategies for minimising intrinsic effects and methods to maximise sensitivity using photon-counting detectors. We discuss on-going work to develop the high speed reconstruction algorithm required for the nlCWFS technique. This includes strategies to implement the technique on graphics processing units (GPUs) and to minimise computing overheads to obtain a prior for a rapid convergence of the wavefront reconstruction. Finally we evaluate the sensitivity of the wavefront sensor based upon both data and low-photon count strategies.

Zinc oxide piezoelectric nano-generators for low frequency applications

NASA Astrophysics Data System (ADS)

Nour, E. S.; Nur, O.; Willander, M.

2017-06-01

Piezoelectric Zinc Oxide (ZnO) nanogenerators (NGs) have been fabricated for low frequency (<100 Hz) energy harvesting applications. Different types of NGs based on ZnO nanostructures have been carefully developed, and studied for testing under different kinds of low frequency mechanical deformations. Well aligned ZnO nanowires (NWs) possessing high piezoelectric coefficient were synthesized on flexible substrates using the low temperature hydrothermal route. These ZnO NWs were then used in different configurations to demonstrate different low frequency energy harvesting devices. Using piezoelectric ZnO NWs, we started with the fabrication of a sandwiched NG for a handwriting enabled energy harvesting device based on a thin silver layer coated paper substrate. Such device configurations can be used for the development of electronic programmable smart paper. Further, we developed this NG to work as a triggered sensor for a wireless system using footstep pressure. These studies demonstrate the feasibility of using a ZnO NWs piezoelectric NG as a low-frequency self- powered sensor, with potential applications in wireless sensor networks. After that, we investigated and fabricated a sensor on a PEDOT: PSS plastic substrate using a one-sided growth and double-sided growth technique. For the first growth technique, the fabricated NG has been used as a sensor for an acceleration system; while the fabricated NG by the second technique works as an anisotropic direction sensor. This fabricated configuration showed stability for sensing and can be used in surveillance, security, and auto-Mobil applications. In addition to that, we investigated the fabrication of a sandwiched NG on plastic substrates. Finally, we demonstrated that doping ZnO NWs with extrinsic elements (such as Ag) will lead to the reduction of the piezoelectric effect due to the loss of crystal symmetry. A brief summary into future opportunities and challenges is also presented.

Embedded Bragg grating fiber optic sensor for composite flexbeams

NASA Astrophysics Data System (ADS)

Bullock, Daniel; Dunphy, James; Hufstetler, Gerard

1993-03-01

An embedded fiber-optic (F-O) sensor has been developed for translaminar monitoring of the structural integrity of composites, with a view to application in composite helicopter flexbeams for bearingless main rotor hubs. This through-thickness strain sensor is much more sensitive than conventional in-plane embedded F-O sensors to ply delamination, on the basis of a novel insertion technique and innovative Bragg grating sensor. Experimental trials have demonstrated the detection by this means of potential failures in advance of the edge-delamination or crack-propagation effect.

Passive Sensor Integration for Vehicle Self-Localization in Urban Traffic Environment †

PubMed Central

Gu, Yanlei; Hsu, Li-Ta; Kamijo, Shunsuke

2015-01-01

This research proposes an accurate vehicular positioning system which can achieve lane-level performance in urban canyons. Multiple passive sensors, which include Global Navigation Satellite System (GNSS) receivers, onboard cameras and inertial sensors, are integrated in the proposed system. As the main source for the localization, the GNSS technique suffers from Non-Line-Of-Sight (NLOS) propagation and multipath effects in urban canyons. This paper proposes to employ a novel GNSS positioning technique in the integration. The employed GNSS technique reduces the multipath and NLOS effects by using the 3D building map. In addition, the inertial sensor can describe the vehicle motion, but has a drift problem as time increases. This paper develops vision-based lane detection, which is firstly used for controlling the drift of the inertial sensor. Moreover, the lane keeping and changing behaviors are extracted from the lane detection function, and further reduce the lateral positioning error in the proposed localization system. We evaluate the integrated localization system in the challenging city urban scenario. The experiments demonstrate the proposed method has sub-meter accuracy with respect to mean positioning error. PMID:26633420

Microelectromechanical system pressure sensor integrated onto optical fiber by anodic bonding.

PubMed

Saran, Anish; Abeysinghe, Don C; Boyd, Joseph T

2006-03-10

Optical microelectromechanical system pressure sensors based on the principle of Fabry-Perot interferometry have been developed and fabricated using the technique of silicon-to-silicon anodic bonding. The pressure sensor is then integrated onto an optical fiber by a novel technique of anodic bonding without use of any adhesives. In this anodic bonding technique we use ultrathin silicon of thickness 10 microm to bond the optical fiber to the sensor head. The ultrathin silicon plays the role of a stress-reducing layer, which helps the bonding of an optical fiber to silicon having conventional wafer thickness. The pressure-sensing membrane is formed by 8 microm thick ultrathin silicon acting as a membrane, thus eliminating the need for bulk silicon etching. The pressure sensor integrated onto an optical fiber is tested for static response, and experimental results indicate degradation in the fringe visibility of the Fabry-Perot interferometer. This effect was mainly due to divergent light rays from the fiber degrading the fringe visibility. This effect is demonstrated in brief by an analytical model.

Recent Developments of Magnetoresistive Sensors for Industrial Applications

PubMed Central

Jogschies, Lisa; Klaas, Daniel; Kruppe, Rahel; Rittinger, Johannes; Taptimthong, Piriya; Wienecke, Anja; Rissing, Lutz; Wurz, Marc Christopher

2015-01-01

The research and development in the field of magnetoresistive sensors has played an important role in the last few decades. Here, the authors give an introduction to the fundamentals of the anisotropic magnetoresistive (AMR) and the giant magnetoresistive (GMR) effect as well as an overview of various types of sensors in industrial applications. In addition, the authors present their recent work in this field, ranging from sensor systems fabricated on traditional substrate materials like silicon (Si), over new fabrication techniques for magnetoresistive sensors on flexible substrates for special applications, e.g., a flexible write head for component integrated data storage, micro-stamping of sensors on arbitrary surfaces or three dimensional sensing under extreme conditions (restricted mounting space in motor air gap, high temperatures during geothermal drilling). PMID:26569263

Recent Advances in Paper-Based Sensors

PubMed Central

Liana, Devi D.; Raguse, Burkhard; Gooding, J. Justin; Chow, Edith

2012-01-01

Paper-based sensors are a new alternative technology for fabricating simple, low-cost, portable and disposable analytical devices for many application areas including clinical diagnosis, food quality control and environmental monitoring. The unique properties of paper which allow passive liquid transport and compatibility with chemicals/biochemicals are the main advantages of using paper as a sensing platform. Depending on the main goal to be achieved in paper-based sensors, the fabrication methods and the analysis techniques can be tuned to fulfill the needs of the end-user. Current paper-based sensors are focused on microfluidic delivery of solution to the detection site whereas more advanced designs involve complex 3-D geometries based on the same microfluidic principles. Although paper-based sensors are very promising, they still suffer from certain limitations such as accuracy and sensitivity. However, it is anticipated that in the future, with advances in fabrication and analytical techniques, that there will be more new and innovative developments in paper-based sensors. These sensors could better meet the current objectives of a viable low-cost and portable device in addition to offering high sensitivity and selectivity, and multiple analyte discrimination. This paper is a review of recent advances in paper-based sensors and covers the following topics: existing fabrication techniques, analytical methods and application areas. Finally, the present challenges and future outlooks are discussed. PMID:23112667

Activity Recognition Invariant to Sensor Orientation with Wearable Motion Sensors.

PubMed

Yurtman, Aras; Barshan, Billur

2017-08-09

Most activity recognition studies that employ wearable sensors assume that the sensors are attached at pre-determined positions and orientations that do not change over time. Since this is not the case in practice, it is of interest to develop wearable systems that operate invariantly to sensor position and orientation. We focus on invariance to sensor orientation and develop two alternative transformations to remove the effect of absolute sensor orientation from the raw sensor data. We test the proposed methodology in activity recognition with four state-of-the-art classifiers using five publicly available datasets containing various types of human activities acquired by different sensor configurations. While the ordinary activity recognition system cannot handle incorrectly oriented sensors, the proposed transformations allow the sensors to be worn at any orientation at a given position on the body, and achieve nearly the same activity recognition performance as the ordinary system for which the sensor units are not rotatable. The proposed techniques can be applied to existing wearable systems without much effort, by simply transforming the time-domain sensor data at the pre-processing stage.

Fiber Optic Thermal Health Monitoring of Composites

NASA Technical Reports Server (NTRS)

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

2010-01-01

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

The Electrophysiological Biosensor for Batch-Measurement of Cell Signals

NASA Astrophysics Data System (ADS)

Suzuki, Kengo; Tanabe, Masato; Ezaki, Takahiro; Konishi, Satoshi; Oka, Hiroaki; Ozaki, Nobuhiko

This paper presents the development of electrophysiological biosensor. The developed sensor allows a batch-measurement by detecting all signals from a large number of cells together. The developed sensor employs the same measurement principle as the patch-clamp technique. A single cell is sucked and clamped in a micro hole with detecting electrode. Detecting electrodes in arrayed micro holes are connected together for the batch-measurement of signals a large number of cell signals. Furthermore, an array of sensors for batch-measurement is designed to improve measurement-throughput to satisfy requirements for the drug screening application.

The Concept of C2 Communication and Information Support

DTIC Science & Technology

2004-06-01

communication and information literacy , • Sensors: technology and systematic development as a branch, • Military prognosis research (combat models...intelligence, • Visualization of actions, suitable forms of information presentation, • Techniques of learning CIS users communication and information ... literacy , • Sensors: technology and systematic development as a branch, • Military prognosis research (combat models), • Man - machine interface. CISu

Virtual Sensors for Designing Irrigation Controllers in Greenhouses

PubMed Central

Sánchez, Jorge Antonio; Rodríguez, Francisco; Guzmán, José Luis; Arahal, Manuel R

2012-01-01

Monitoring the greenhouse transpiration for control purposes is currently a difficult task. The absence of affordable sensors that provide continuous transpiration measurements motivates the use of estimators. In the case of tomato crops, the availability of estimators allows the design of automatic fertirrigation (irrigation + fertilization) schemes in greenhouses, minimizing the dispensed water while fulfilling crop needs. This paper shows how system identification techniques can be applied to obtain nonlinear virtual sensors for estimating transpiration. The greenhouse used for this study is equipped with a microlysimeter, which allows one to continuously sample the transpiration values. While the microlysimeter is an advantageous piece of equipment for research, it is also expensive and requires maintenance. This paper presents the design and development of a virtual sensor to model the crop transpiration, hence avoiding the use of this kind of expensive sensor. The resulting virtual sensor is obtained by dynamical system identification techniques based on regressors taken from variables typically found in a greenhouse, such as global radiation and vapor pressure deficit. The virtual sensor is thus based on empirical data. In this paper, some effort has been made to eliminate some problems associated with grey-box models: advance phenomenon and overestimation. The results are tested with real data and compared with other approaches. Better results are obtained with the use of nonlinear Black-box virtual sensors. This sensor is based on global radiation and vapor pressure deficit (VPD) measurements. Predictive results for the three models are developed for comparative purposes. PMID:23202208

Uniformly Porous Nanocrystalline CaMgFe1.33Ti3O12 Ceramic Derived Electro-Ceramic Nanocomposite for Impedance Type Humidity Sensor

PubMed Central

Tripathy, Ashis; Pramanik, Sumit; Manna, Ayan; Shasmin, Hanie Nadia; Radzi, Zamri; Abu Osman, Noor Azuan

2016-01-01

Since humidity sensors have been widely used in many sectors, a suitable humidity sensing material with improved sensitivity, faster response and recovery times, better stability and low hysteresis is necessary to be developed. Here, we fabricate a uniformly porous humidity sensor using Ca, Ti substituted Mg ferrites with chemical formula of CaMgFe1.33Ti3O12 as humidity sensing materials by solid-sate step-sintering technique. This synthesis technique is useful to control the grain size with increased porosity to enhance the hydrophilic characteristics of the CaMgFe1.33Ti3O12 nanoceramic based sintered electro-ceramic nanocomposites. The highest porosity, lowest density and excellent surface-hydrophilicity properties were obtained at 1050 °C sintered ceramic. The performance of this impedance type humidity sensor was evaluated by electrical characterizations using alternating current (AC) in the 33%–95% relative humidity (RH) range at 25 °C. Compared with existing conventional resistive humidity sensors, the present sintered electro-ceramic nanocomposite based humidity sensor showed faster response time (20 s) and recovery time (40 s). This newly developed sensor showed extremely high sensitivity (%S) and small hysteresis of <3.4%. Long-term stability of the sensor had been determined by testing for 30 consecutive days. Therefore, the high performance sensing behavior of the present electro-ceramic nanocomposites would be suitable for a potential use in advanced humidity sensors. PMID:27916913

Time-Of-Flight Camera, Optical Tracker and Computed Tomography in Pairwise Data Registration.

PubMed

Pycinski, Bartlomiej; Czajkowska, Joanna; Badura, Pawel; Juszczyk, Jan; Pietka, Ewa

2016-01-01

A growing number of medical applications, including minimal invasive surgery, depends on multi-modal or multi-sensors data processing. Fast and accurate 3D scene analysis, comprising data registration, seems to be crucial for the development of computer aided diagnosis and therapy. The advancement of surface tracking system based on optical trackers already plays an important role in surgical procedures planning. However, new modalities, like the time-of-flight (ToF) sensors, widely explored in non-medical fields are powerful and have the potential to become a part of computer aided surgery set-up. Connection of different acquisition systems promises to provide a valuable support for operating room procedures. Therefore, the detailed analysis of the accuracy of such multi-sensors positioning systems is needed. We present the system combining pre-operative CT series with intra-operative ToF-sensor and optical tracker point clouds. The methodology contains: optical sensor set-up and the ToF-camera calibration procedures, data pre-processing algorithms, and registration technique. The data pre-processing yields a surface, in case of CT, and point clouds for ToF-sensor and marker-driven optical tracker representation of an object of interest. An applied registration technique is based on Iterative Closest Point algorithm. The experiments validate the registration of each pair of modalities/sensors involving phantoms of four various human organs in terms of Hausdorff distance and mean absolute distance metrics. The best surface alignment was obtained for CT and optical tracker combination, whereas the worst for experiments involving ToF-camera. The obtained accuracies encourage to further develop the multi-sensors systems. The presented substantive discussion concerning the system limitations and possible improvements mainly related to the depth information produced by the ToF-sensor is useful for computer aided surgery developers.

Intelligent Devices - Sensors and Actuators - A KSC Perspective

NASA Technical Reports Server (NTRS)

Mata, Carlos T.; Perotti, Jose M.

2008-01-01

The primary objective of this workshop is to identify areas of advancement in sensor measurements and technologies that will help to define standard practices and procedures that will better enable the infusion into flight programs of sensors with improved capabilities but limited or no flight heritage. These standards would be crucial to demonstrating a methodology for validating current models while also creating the possibility of being able to have sufficient data to either update these models (e. g., spatial or temporal resolution, etc.) or develop new models based on the ability to simulate the new measured physical parameters. The workshop is also intended to narrow the gap between sensor measurements (and techniques), data processing techniques and the ability to make use of that data by gathering together experts in the field for a short workshop. This collaboration will unite NASA and other government agencies with contractor capabilities industry-wide to prevent duplication, spawn synergistic growth in sensor technology, help analysts make good engineering decisions and help focus new sensor maturation efforts to better meet future flight program customers' needs. This is the first such workshop designed to specifically address establishing a standardized protocol/methodology for demonstrating the technology readiness of non-flight heritage sensor systems. While other similar workshops are held covering many areas of interest to the sensor development community, no other meeting is specific enough to address this vital but often overlooked topic. By encouraging cross-fertilization of ideas from instrument experts from many different backgrounds, it is hoped that this workshop will initiate innovative new ideas and concepts in sensor development, calibration and validation. It is anticipated this workshop will repeat periodically as needed.

Distributed sensor for water and pH measurements using fiber optics and swellable polymeric systems

NASA Astrophysics Data System (ADS)

Michie, W. C.; Culshaw, B.; McKenzie, I.; Konstantakis, M.; Graham, N. B.; Moran, C.; Santos, F.; Bergqvist, E.; Carlstrom, B.

1995-01-01

We report on the design, construction and test of a generic form of sensor for making distributed measurements of a range of chemical parameters. The technique combines optical time-domain reflectometry with chemically sensitive water-swellable polymers (hydrogels). Initial experiments have concentrated on demonstrating a distributed water detector; however, gels have been developed that enable this sensor to be

Six component robotic force-torque sensor

NASA Technical Reports Server (NTRS)

Grahn, Allen R.; Hutchings, Brad L.; Johnston, David R.; Parsons, David C.; Wyatt, Roland F.

1987-01-01

The results of a two-phase contract studying the feasibility of a miniaturized six component force-torque sensor and development of a working laboratory system were described. The principle of operation is based upon using ultrasonic pulse-echo ranging to determine the position of ultrasonic reflectors attached to a metal or ceramic cover plate. Because of the small size of the sensor, this technology may have application in robotics, to sense forces and torques at the finger tip of a robotic end effector. Descriptions are included of laboratory experiments evaluating materials and techniques for sensor fabrication and of the development of support electronics for data acquisition, computer interface, and operator display.

Calibration of High Heat Flux Sensors at NIST

PubMed Central

Murthy, A. V.; Tsai, B. K.; Gibson, C. E.

1997-01-01

An ongoing program at the National Institute of Standards and Technology (NIST) is aimed at improving and standardizing heat-flux sensor calibration methods. The current calibration needs of U.S. science and industry exceed the current NIST capability of 40 kW/m2 irradiance. In achieving this goal, as well as meeting lower-level non-radiative heat flux calibration needs of science and industry, three different types of calibration facilities currently are under development at NIST: convection, conduction, and radiation. This paper describes the research activities associated with the NIST Radiation Calibration Facility. Two different techniques, transfer and absolute, are presented. The transfer calibration technique employs a transfer standard calibrated with reference to a radiometric standard for calibrating the sensors using a graphite tube blackbody. Plans for an absolute calibration facility include the use of a spherical blackbody and a cooled aperture and sensor-housing assembly to calibrate the sensors in a low convective environment. PMID:27805156

Validation of polyvinylidene fluoride nasal sensor to assess nasal obstruction in comparison with subjective technique.

PubMed

Roopa Manjunatha, G; Mahapatra, D Roy; Prakash, Surya; Rajanna, K

2015-01-01

The aim of this study is to validate the applicability of the PolyVinyliDene Fluoride (PVDF) nasal sensor to assess the nasal airflow, in healthy subjects and patients with nasal obstruction and to correlate the results with the score of Visual Analogue Scale (VAS). PVDF nasal sensor and VAS measurements were carried out in 50 subjects (25-healthy subjects and 25 patients). The VAS score of nasal obstruction and peak-to-peak amplitude (Vp-p) of nasal cycle measured by PVDF nasal sensors were analyzed for right nostril (RN) and left nostril (LN) in both the groups. Spearman's rho correlation was calculated. The relationship between PVDF nasal sensor measurements and severity of nasal obstruction (VAS score) were assessed by ANOVA. In healthy group, the measurement of nasal airflow by PVDF nasal sensor for RN and LN were found to be 51.14±5.87% and 48.85±5.87%, respectively. In patient group, PVDF nasal sensor indicated lesser nasal airflow in the blocked nostrils (RN: 23.33±10.54% and LN: 32.24±11.54%). Moderate correlation was observed in healthy group (r=-0.710, p<0.001 for RN and r=-0.651, p<0.001 for LN), and moderate to strong correlation in patient group (r=-0.751, p<0.01 for RN and r=-0.885, p<0.0001 for LN). PVDF nasal sensor method is a newly developed technique for measuring the nasal airflow. Moderate to strong correlation was observed between PVDF nasal sensor data and VAS scores for nasal obstruction. In our present study, PVDF nasal sensor technique successfully differentiated between healthy subjects and patients with nasal obstruction. Additionally, it can also assess severity of nasal obstruction in comparison with VAS. Thus, we propose that the PVDF nasal sensor technique could be used as a new diagnostic method to evaluate nasal obstruction in routine clinical practice. Copyright © 2015 Elsevier Inc. All rights reserved.

Method and apparatus for phase for and amplitude detection

DOEpatents

Cernosek, Richard W.; Frye, Gregory C.; Martin, Stephen J.

1998-06-09

A new class of techniques been developed which allow inexpensive application of SAW-type chemical sensor devices while retaining high sensitivity (ppm) to chemical detection. The new techniques do not require that the sensor be part of an oscillatory circuit, allowing large concentrations of, e.g., chemical vapors in air, to be accurately measured without compromising the capacity to measure trace concentrations. Such devices have numerous potential applications in environmental monitoring, from manufacturing environments to environmental restoration.

Enviro-Net: From Networks of Ground-Based Sensor Systems to a Web Platform for Sensor Data Management

PubMed Central

Pastorello, Gilberto Z.; Sanchez-Azofeifa, G. Arturo; Nascimento, Mario A.

2011-01-01

Ecosystems monitoring is essential to properly understand their development and the effects of events, both climatological and anthropological in nature. The amount of data used in these assessments is increasing at very high rates. This is due to increasing availability of sensing systems and the development of new techniques to analyze sensor data. The Enviro-Net Project encompasses several of such sensor system deployments across five countries in the Americas. These deployments use a few different ground-based sensor systems, installed at different heights monitoring the conditions in tropical dry forests over long periods of time. This paper presents our experience in deploying and maintaining these systems, retrieving and pre-processing the data, and describes the Web portal developed to help with data management, visualization and analysis. PMID:22163965

Conductive ink print on PA66 gear for manufacturing condition monitoring sensors

NASA Astrophysics Data System (ADS)

Futagawa, Shintaro; Iba, Daisuke; Kamimoto, Takahiro; Nakamura, Morimasa; Miura, Nanako; Iizuka, Takashi; Masuda, Arata; Sone, Akira; Moriwaki, Ichiro

2018-03-01

Failures detection of rotating machine elements, such as gears, is an important issue. The purpose of this study was to try to solve this issue by printing conductive ink on gears to manufacture condition-monitoring sensors. In this work, three types of crack detection sensor were designed and the sprayed conductive ink was directly sintered on polyimide (PI) - coated polyamide (PA) 66 gears by laser. The result showed that it was possible to produce narrow circuit lines of the conductive ink including Ag by laser sintering technique and the complex shape sensors on the lateral side of the PA66 gears, module 1.0 mm and tooth number 48. A preliminary operation test was carried out for investigation of the function of the sensors. As a result of the test, the sensors printed in this work should be effective for detecting cracks at tooth root of the gears and will allow for the development of better equipment and detection techniques for health monitoring of gears.

Wet etching technique for fabrication of a high-quality plastic optical fiber sensor.

PubMed

Zhao, Mingfu; Dai, Lang; Zhong, Nianbing; Wang, Zhengkun; Chen, Ming; Li, Bingxin; Luo, Binbin; Tang, Bin; Shi, Shenghui; Song, Tao; Zou, Xue

2017-11-01

In this study, a simple wet etching technique is developed by employing aqueous solutions of acetic acid and ultrasonic irradiation for the fabrication of a high-quality plastic optical fiber (POF) sensor. The effects of acetic acid concentration and temperature and ultrasonic power on the etching rate and surface morphology of the etched POFs are investigated. The transmission spectrum and sensitivity of the etched POF sensors are evaluated using glucose solutions. We discovered that the POF sensors, which are fabricated using an aqueous solution of acetic acid with a concentration of 80 vol. % under an ultrasonic power of 130 W and temperature of 25°C, exhibit good light transmission and a high sensitivity of 9.10  [(RIU)(g/L)] -1 in the glucose solutions.

Development of metal oxide impregnated stilbite thick film ethanol sensor

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

Mahabole, M. P., E-mail: kashinath.bogle@gmail.com; Lakhane, M. A.; Choudhari, A. L.

This paper presents the study of the sensing efficiency of Titanium oxide/ Stilbite and Copper oxide /Stilbite composites towards detection of hazardous pollutants like ethanol. Stilbite based composites are prepared by physically mixing zeolite with metal oxides namely TiO{sub 2} and CuO with weight ratios of 25:75, 50:50 and 75:25. The resulting sensor materials are characterized by X-ray diffraction and Fourier Transform Infrared Spectroscopy techniques. Composite sensors are fabricated in the form of thick film by using screen printing technique. The effect of metal oxide concentration on various ethanol sensing parameters such as operating temperature, maximum uptake capacity and response/recoverymore » time are investigated. The results indicate that metal oxide impregnated stilbite composites have great potential as low temperature ethanol sensor.« less

Development of metal oxide impregnated stilbite thick film ethanol sensor

NASA Astrophysics Data System (ADS)

Mahabole, M. P.; Lakhane, M. A.; Choudhari, A. L.; Khairnar, R. S.

2016-05-01

This paper presents the study of the sensing efficiency of Titanium oxide/ Stilbite and Copper oxide /Stilbite composites towards detection of hazardous pollutants like ethanol. Stilbite based composites are prepared by physically mixing zeolite with metal oxides namely TiO2 and CuO with weight ratios of 25:75, 50:50 and 75:25. The resulting sensor materials are characterized by X-ray diffraction and Fourier Transform Infrared Spectroscopy techniques. Composite sensors are fabricated in the form of thick film by using screen printing technique. The effect of metal oxide concentration on various ethanol sensing parameters such as operating temperature, maximum uptake capacity and response/recovery time are investigated. The results indicate that metal oxide impregnated stilbite composites have great potential as low temperature ethanol sensor.

Development of calibration techniques for ultrasonic hydrophone probes in the frequency range from 1 to 100 MHz

PubMed Central

Umchid, S.; Gopinath, R.; Srinivasan, K.; Lewin, P. A.; Daryoush, A. S.; Bansal, L.; El-Sherif, M.

2009-01-01

The primary objective of this work was to develop and optimize the calibration techniques for ultrasonic hydrophone probes used in acoustic field measurements up to 100 MHz. A dependable, 100 MHz calibration method was necessary to examine the behavior of a sub-millimeter spatial resolution fiber optic (FO) sensor and assess the need for such a sensor as an alternative tool for high frequency characterization of ultrasound fields. Also, it was of interest to investigate the feasibility of using FO probes in high intensity fields such as those employed in HIFU (High Intensity Focused Ultrasound) applications. In addition to the development and validation of a novel, 100 MHz calibration technique the innovative elements of this research include implementation and testing of a prototype FO sensor with an active diameter of about 10 μm that exhibits uniform sensitivity over the considered frequency range and does not require any spatial averaging corrections up to about 75 MHz. The results of the calibration measurements are presented and it is shown that the optimized calibration technique allows the sensitivity of the hydrophone probes to be determined as a virtually continuous function of frequency and is also well suited to verify the uniformity of the FO sensor frequency response. As anticipated, the overall uncertainty of the calibration was dependent on frequency and determined to be about ±12% (±1 dB) up to 40 MHz, ±20% (±1.5 dB) from 40 to 60 MHz and ±25% (±2 dB) from 60 to 100 MHz. The outcome of this research indicates that once fully developed and calibrated, the combined acousto-optic system will constitute a universal reference tool in the wide, 100 MHz bandwidth. PMID:19110289

Development and Applications of a Self-Contained, Non-Invasive EVA Joint Angle and Muscle Fatigue Sensor System

NASA Technical Reports Server (NTRS)

Ranniger, C. U.; Sorenson, E. A.; Akin, D. L.

1995-01-01

The University of Maryland Space Systems Laboratory, as a participant in NASA's INSTEP program, is developing a non-invasive, self-contained sensor system which can provide quantitative measurements of joint angles and muscle fatigue in the hand and forearm. The goal of this project is to develop a system with which hand/forearm motion and fatigue metrics can be determined in various terrestrial and zero-G work environments. A preliminary study of the prototype sensor systems and data reduction techniques for the fatigue measurement system are presented. The sensor systems evaluated include fiberoptics, used to measure joint angle, surface electrodes, which measure the electrical signals created in muscle as it contracts; microphones, which measure the noise made by contracting muscle; and accelerometers, which measure the lateral muscle acceleration during contraction. The prototype sensor systems were used to monitor joint motion of the metacarpophalangeal joint and muscle fatigue in flexor digitorum superficialis and flexor carpi ulnaris in subjects performing gripping tasks. Subjects were asked to sustain a 60-second constant-contraction (isometric) exercise and subsequently to perform a repetitive handgripping task to failure. Comparison of the electrical and mechanical signals of the muscles during the different tasks will be used to evaluate the applicability of muscle signal measurement techniques developed for isometric contraction tasks to fatigue prediction in quasi-dynamic exercises. Potential data reduction schemes are presented.

Nanophotonic Image Sensors.

PubMed

Chen, Qin; Hu, Xin; Wen, Long; Yu, Yan; Cumming, David R S

2016-09-01

The increasing miniaturization and resolution of image sensors bring challenges to conventional optical elements such as spectral filters and polarizers, the properties of which are determined mainly by the materials used, including dye polymers. Recent developments in spectral filtering and optical manipulating techniques based on nanophotonics have opened up the possibility of an alternative method to control light spectrally and spatially. By integrating these technologies into image sensors, it will become possible to achieve high compactness, improved process compatibility, robust stability and tunable functionality. In this Review, recent representative achievements on nanophotonic image sensors are presented and analyzed including image sensors with nanophotonic color filters and polarizers, metamaterial-based THz image sensors, filter-free nanowire image sensors and nanostructured-based multispectral image sensors. This novel combination of cutting edge photonics research and well-developed commercial products may not only lead to an important application of nanophotonics but also offer great potential for next generation image sensors beyond Moore's Law expectations. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Fiber-Optic Borehole Seismic Vector Sensor System for Geothermal Site Characterization and Monitoring

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

Paulsson, Bjorn N.P.; Thornburg, Jon A.; He, Ruiqing

2015-04-21

Seismic techniques are the dominant geophysical techniques for the characterization of subsurface structures and stratigraphy. The seismic techniques also dominate the monitoring and mapping of reservoir injection and production processes. Borehole seismology, of all the seismic techniques, despite its current shortcomings, has been shown to provide the highest resolution characterization and most precise monitoring results because it generates higher signal to noise ratio and higher frequency data than surface seismic techniques. The operational environments for borehole seismic instruments are however much more demanding than for surface seismic instruments making both the instruments and the installation much more expensive. The currentmore » state-of-the-art borehole seismic instruments have not been robust enough for long term monitoring compounding the problems with expensive instruments and installations. Furthermore, they have also not been able to record the large bandwidth data available in boreholes or having the sensitivity allowing them to record small high frequency micro seismic events with high vector fidelity. To reliably achieve high resolution characterization and long term monitoring of Enhanced Geothermal Systems (EGS) sites a new generation of borehole seismic instruments must therefore be developed and deployed. To address the critical site characterization and monitoring needs for EGS programs, US Department of Energy (DOE) funded Paulsson, Inc. in 2010 to develop a fiber optic based ultra-large bandwidth clamped borehole seismic vector array capable of deploying up to one thousand 3C sensor pods suitable for deployment into ultra-high temperature and high pressure boreholes. Tests of the fiber optic seismic vector sensors developed on the DOE funding have shown that the new borehole seismic sensor technology is capable of generating outstanding high vector fidelity data with extremely large bandwidth: 0.01 – 6,000 Hz. Field tests have shown that the system can record events at magnitudes much smaller than M-2.6 at frequencies up to 2,000 Hz. The sensors have also proved to be about 100 times more sensitive than the regular coil geophones that are used in borehole seismic systems today. The fiber optic seismic sensors have furthermore been qualified to operate at temperatures over 300°C (572°F). Simultaneously with the fiber optic based seismic 3C vector sensors we are using the lead-in fiber to acquire Distributed Acoustic Sensor (DAS) data from the surface to the bottom of the vector array. While the DAS data is of much lower quality than the vector sensor data it provides a 1 m spatial sampling of the downgoing wavefield which will be used to build the high resolution velocity model which is an essential component in high resolution imaging and monitoring.« less

Development and characterization of an IPMC hair-like transducer

NASA Astrophysics Data System (ADS)

Akle, Barbar J.; Challita, Elio; Khairalah, Nady

2015-04-01

Hair-like sensors are very common in natural and biological systems. Such sensors are used to measure acoustic pressures, fluid flows, and chemical concentrations among others. Hair-like actuators are also used to control fluid flows and perform temperature management. This study presents a manufacturing technique for a hair-like IPMC transducer. A thorough study is presented on the building process of the sensor. The method used to control the diameter and the electrodes thickness of the transducer is developed. The sensing behavior of the manufactured transducers is experimentally characterized.

A Passive Wireless Multi-Sensor SAW Technology Device and System Perspectives

PubMed Central

Malocha, Donald C.; Gallagher, Mark; Fisher, Brian; Humphries, James; Gallagher, Daniel; Kozlovski, Nikolai

2013-01-01

This paper will discuss a SAW passive, wireless multi-sensor system under development by our group for the past several years. The device focus is on orthogonal frequency coded (OFC) SAW sensors, which use both frequency diversity and pulse position reflectors to encode the device ID and will be briefly contrasted to other embodiments. A synchronous correlator transceiver is used for the hardware and post processing and correlation techniques of the received signal to extract the sensor information will be presented. Critical device and system parameters addressed include encoding, operational range, SAW device parameters, post-processing, and antenna-SAW device integration. A fully developed 915 MHz OFC SAW multi-sensor system is used to show experimental results. The system is based on a software radio approach that provides great flexibility for future enhancements and diverse sensor applications. Several different sensor types using the OFC SAW platform are shown. PMID:23666124

A new fiber optic sensor for inner surface roughness measurement

NASA Astrophysics Data System (ADS)

Xu, Xiaomei; Liu, Shoubin; Hu, Hong

2009-11-01

In order to measure inner surface roughness of small holes nondestructively, a new fiber optic sensor is researched and developed. Firstly, a new model for surface roughness measurement is proposed, which is based on intensity-modulated fiber optic sensors and scattering modeling of rough surfaces. Secondly, a fiber optical measurement system is designed and set up. Under the help of new techniques, the fiber optic sensor can be miniaturized. Furthermore, the use of micro prism makes the light turn 90 degree, so the inner side surface roughness of small holes can be measured. Thirdly, the fiber optic sensor is gauged by standard surface roughness specimens, and a series of measurement experiments have been done. The measurement results are compared with those obtained by TR220 Surface Roughness Instrument and Form Talysurf Laser 635, and validity of the developed fiber optic sensor is verified. Finally, precision and influence factors of the fiber optic sensor are analyzed.

Hybrid Arrays for Chemical Sensing

NASA Astrophysics Data System (ADS)

Kramer, Kirsten E.; Rose-Pehrsson, Susan L.; Johnson, Kevin J.; Minor, Christian P.

In recent years, multisensory approaches to environment monitoring for chemical detection as well as other forms of situational awareness have become increasingly popular. A hybrid sensor is a multimodal system that incorporates several sensing elements and thus produces data that are multivariate in nature and may be significantly increased in complexity compared to data provided by single-sensor systems. Though a hybrid sensor is itself an array, hybrid sensors are often organized into more complex sensing systems through an assortment of network topologies. Part of the reason for the shift to hybrid sensors is due to advancements in sensor technology and computational power available for processing larger amounts of data. There is also ample evidence to support the claim that a multivariate analytical approach is generally superior to univariate measurements because it provides additional redundant and complementary information (Hall, D. L.; Linas, J., Eds., Handbook of Multisensor Data Fusion, CRC, Boca Raton, FL, 2001). However, the benefits of a multisensory approach are not automatically achieved. Interpretation of data from hybrid arrays of sensors requires the analyst to develop an application-specific methodology to optimally fuse the disparate sources of data generated by the hybrid array into useful information characterizing the sample or environment being observed. Consequently, multivariate data analysis techniques such as those employed in the field of chemometrics have become more important in analyzing sensor array data. Depending on the nature of the acquired data, a number of chemometric algorithms may prove useful in the analysis and interpretation of data from hybrid sensor arrays. It is important to note, however, that the challenges posed by the analysis of hybrid sensor array data are not unique to the field of chemical sensing. Applications in electrical and process engineering, remote sensing, medicine, and of course, artificial intelligence and robotics, all share the same essential data fusion challenges. The design of a hybrid sensor array should draw on this extended body of knowledge. In this chapter, various techniques for data preprocessing, feature extraction, feature selection, and modeling of sensor data will be introduced and illustrated with data fusion approaches that have been implemented in applications involving data from hybrid arrays. The example systems discussed in this chapter involve the development of prototype sensor networks for damage control event detection aboard US Navy vessels and the development of analysis algorithms to combine multiple sensing techniques for enhanced remote detection of unexploded ordnance (UXO) in both ground surveys and wide area assessments.

Structural health management of aerospace hotspots under fatigue loading

NASA Astrophysics Data System (ADS)

Soni, Sunilkumar

Sustainability and life-cycle assessments of aerospace systems, such as aircraft structures and propulsion systems, represent growing challenges in engineering. Hence, there has been an increasing demand in using structural health monitoring (SHM) techniques for continuous monitoring of these systems in an effort to improve safety and reduce maintenance costs. The current research is part of an ongoing multidisciplinary effort to develop a robust SHM framework resulting in improved models for damage-state awareness and life prediction, and enhancing capability of future aircraft systems. Lug joints, a typical structural hotspot, were chosen as the test article for the current study. The thesis focuses on integrated SHM techniques for damage detection and characterization in lug joints. Piezoelectric wafer sensors (PZTs) are used to generate guided Lamb waves as they can be easily used for onboard applications. Sensor placement in certain regions of a structural component is not feasible due to the inaccessibility of the area to be monitored. Therefore, a virtual sensing concept is introduced to acquire sensor data from finite element (FE) models. A full three dimensional FE analysis of lug joints with piezoelectric transducers, accounting for piezoelectrical-mechanical coupling, was performed in Abaqus and the sensor signals were simulated. These modeled sensors are called virtual sensors. A combination of real data from PZTs and virtual sensing data from FE analysis is used to monitor and detect fatigue damage in aluminum lug joints. Experiments were conducted on lug joints under fatigue loads and sensor signals collected were used to validate the simulated sensor response. An optimal sensor placement methodology for lug joints is developed based on a detection theory framework to maximize the detection rate and minimize the false alarm rate. The placement technique is such that the sensor features can be directly correlated to damage. The technique accounts for a number of factors, such as actuation frequency and strength, minimum damage size, damage detection scheme, material damping, signal to noise ratio and sensing radius. Advanced information processing methodologies are discussed for damage diagnosis. A new, instantaneous approach for damage detection, localization and quantification is proposed for applications to practical problems associated with changes in reference states under different environmental and operational conditions. Such an approach improves feature extraction for state awareness, resulting in robust life prediction capabilities.

Methods and Piezoelectric Imbedded Sensors for Damage Detection in Composite Plates Under Ambient and Cryogenic Conditions

NASA Technical Reports Server (NTRS)

Engberg, Robert; Ooi, Teng K.

2004-01-01

New methods for structural health monitoring are being assessed, especially in high-performance, extreme environment, safety-critical applications. One such application is for composite cryogenic fuel tanks. The work presented here attempts to characterize and investigate the feasibility of using imbedded piezoelectric sensors to detect cracks and delaminations under cryogenic and ambient conditions. A variety of damage detection methods and different Sensors are employed in the different composite plate samples to aid in determining an optimal algorithm, sensor placement strategy, and type of imbedded sensor to use. Variations of frequency, impedance measurements, and pulse echoing techniques of the sensors are employed and compared. Statistical and analytic techniques are then used to determine which method is most desirable for a specific type of damage. These results are furthermore compared with previous work using externally mounted sensors. Results and optimized methods from this work can then be incorporated into a larger composite structure to validate and assess its structural health. This could prove to be important in the development and qualification of any 2" generation reusable launch vehicle using composites as a structural element.

Biology-Inspired Distributed Consensus in Massively-Deployed Sensor Networks

NASA Technical Reports Server (NTRS)

Jones, Kennie H.; Lodding, Kenneth N.; Olariu, Stephan; Wilson, Larry; Xin, Chunsheng

2005-01-01

Promises of ubiquitous control of the physical environment by large-scale wireless sensor networks open avenues for new applications that are expected to redefine the way we live and work. Most of recent research has concentrated on developing techniques for performing relatively simple tasks in small-scale sensor networks assuming some form of centralized control. The main contribution of this work is to propose a new way of looking at large-scale sensor networks, motivated by lessons learned from the way biological ecosystems are organized. Indeed, we believe that techniques used in small-scale sensor networks are not likely to scale to large networks; that such large-scale networks must be viewed as an ecosystem in which the sensors/effectors are organisms whose autonomous actions, based on local information, combine in a communal way to produce global results. As an example of a useful function, we demonstrate that fully distributed consensus can be attained in a scalable fashion in massively deployed sensor networks where individual motes operate based on local information, making local decisions that are aggregated across the network to achieve globally-meaningful effects.

Chemical Sensor Array Response Modeling Using Quantitative Structure-Activity Relationships Technique

NASA Astrophysics Data System (ADS)

Shevade, Abhijit V.; Ryan, Margaret A.; Homer, Margie L.; Zhou, Hanying; Manfreda, Allison M.; Lara, Liana M.; Yen, Shiao-Pin S.; Jewell, April D.; Manatt, Kenneth S.; Kisor, Adam K.

We have developed a Quantitative Structure-Activity Relationships (QSAR) based approach to correlate the response of chemical sensors in an array with molecular descriptors. A novel molecular descriptor set has been developed; this set combines descriptors of sensing film-analyte interactions, representing sensor response, with a basic analyte descriptor set commonly used in QSAR studies. The descriptors are obtained using a combination of molecular modeling tools and empirical and semi-empirical Quantitative Structure-Property Relationships (QSPR) methods. The sensors under investigation are polymer-carbon sensing films which have been exposed to analyte vapors at parts-per-million (ppm) concentrations; response is measured as change in film resistance. Statistically validated QSAR models have been developed using Genetic Function Approximations (GFA) for a sensor array for a given training data set. The applicability of the sensor response models has been tested by using it to predict the sensor activities for test analytes not considered in the training set for the model development. The validated QSAR sensor response models show good predictive ability. The QSAR approach is a promising computational tool for sensing materials evaluation and selection. It can also be used to predict response of an existing sensing film to new target analytes.

A Localized Surface Plasmon Resonance Sensor Using Double-Metal-Complex Nanostructures and a Review of Recent Approaches

PubMed Central

Ahn, Heesang; Song, Hyerin; Kim, Kyujung

2017-01-01

From active developments and applications of various devices to acquire outside and inside information and to operate based on feedback from that information, the sensor market is growing rapidly. In accordance to this trend, the surface plasmon resonance (SPR) sensor, an optical sensor, has been actively developed for high-sensitivity real-time detection. In this study, the fundamentals of SPR sensors and recent approaches for enhancing sensing performance are reported. In the section on the fundamentals of SPR sensors, a brief description of surface plasmon phenomena, SPR, SPR-based sensing applications, and several configuration types of SPR sensors are introduced. In addition, advanced nanotechnology- and nanofabrication-based techniques for improving the sensing performance of SPR sensors are proposed: (1) localized SPR (LSPR) using nanostructures or nanoparticles; (2) long-range SPR (LRSPR); and (3) double-metal-layer SPR sensors for additional performance improvements. Consequently, a high-sensitivity, high-biocompatibility SPR sensor method is suggested. Moreover, we briefly describe issues (miniaturization and communication technology integration) for future SPR sensors. PMID:29301238

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

NASA Technical Reports Server (NTRS)

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

2017-01-01

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

Survey of Visual and Force/Tactile Control of Robots for Physical Interaction in Spain

PubMed Central

Garcia, Gabriel J.; Corrales, Juan A.; Pomares, Jorge; Torres, Fernando

2009-01-01

Sensors provide robotic systems with the information required to perceive the changes that happen in unstructured environments and modify their actions accordingly. The robotic controllers which process and analyze this sensory information are usually based on three types of sensors (visual, force/torque and tactile) which identify the most widespread robotic control strategies: visual servoing control, force control and tactile control. This paper presents a detailed review on the sensor architectures, algorithmic techniques and applications which have been developed by Spanish researchers in order to implement these mono-sensor and multi-sensor controllers which combine several sensors. PMID:22303146

Microfabricated Chemical Sensors for Aerospace Fire Detection Applications

NASA Technical Reports Server (NTRS)

Hunter, Gary W.; Neudeck, Philip G.; Fralick, Gustave; Thomas, Valarie; Makel, D.; Liu, C. C.; Ward, B.; Wu, Q. H.

2001-01-01

The detection of fires on-board commercial aircraft is extremely important for safety reasons. Although dependable fire detection equipment presently exists within the cabin, detection of fire within the cargo hold has been less reliable and susceptible to false alarms. A second, independent method of fire detection to complement the conventional smoke detection techniques, such as the measurement of chemical species indicative of a fire, will help reduce false alarms and improve aircraft safety. Although many chemical species are indicative of a fire, two species of particular interest are CO and CO2. This paper discusses microfabricated chemical sensor development tailored to meet the needs of fire safety applications. This development is based on progress in three types of technology: 1) Micromachining and microfabrication (Microsystem) technology to fabricate miniaturized sensors. 2) The use of nanocrystalline materials to develop sensors with improved stability combined with higher sensitivity. 3) The development of high temperature semiconductors, especially silicon carbide. The individual sensor being developed and their level of maturity will be presented.

Employing a new bath- and liquidus temperature sensor for molten salts

NASA Astrophysics Data System (ADS)

Verstreken, P.

1997-11-01

In this article, a newly developed sensor that measures bath and liquidus temperatures is described. The accuracy and reproducibility of the sensor are discussed, and the sensor’s output is compared with results obtained using other techniques. A series of measurements in point-feed and center-worked cells are given. Finally, the evolution of bath and liquidus temperature is shown with respect to feed strategies.

Accuracy Enhancement of Inertial Sensors Utilizing High Resolution Spectral Analysis

PubMed Central

Noureldin, Aboelmagd; Armstrong, Justin; El-Shafie, Ahmed; Karamat, Tashfeen; McGaughey, Don; Korenberg, Michael; Hussain, Aini

2012-01-01

In both military and civilian applications, the inertial navigation system (INS) and the global positioning system (GPS) are two complementary technologies that can be integrated to provide reliable positioning and navigation information for land vehicles. The accuracy enhancement of INS sensors and the integration of INS with GPS are the subjects of widespread research. Wavelet de-noising of INS sensors has had limited success in removing the long-term (low-frequency) inertial sensor errors. The primary objective of this research is to develop a novel inertial sensor accuracy enhancement technique that can remove both short-term and long-term error components from inertial sensor measurements prior to INS mechanization and INS/GPS integration. A high resolution spectral analysis technique called the fast orthogonal search (FOS) algorithm is used to accurately model the low frequency range of the spectrum, which includes the vehicle motion dynamics and inertial sensor errors. FOS models the spectral components with the most energy first and uses an adaptive threshold to stop adding frequency terms when fitting a term does not reduce the mean squared error more than fitting white noise. The proposed method was developed, tested and validated through road test experiments involving both low-end tactical grade and low cost MEMS-based inertial systems. The results demonstrate that in most cases the position accuracy during GPS outages using FOS de-noised data is superior to the position accuracy using wavelet de-noising.

NOx Sensor for Direct Injection Emission Control

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

Betteridge, William J

2006-02-28

The Electricore/Delphi team continues to leverage the electrochemical planar sensor technology that has produced stoichiometric planar and wide range oxygen sensors as the basis for development of a NOx sensor. Zirconia cell technology with an integrated heater will provide the foundation for the sensor structure. Proven materials and packaging technology will help to ensure a cost-effective approach to the manufacture of this sensor. The electronics technique and interface is considered to be an area where new strategies need to be employed to produce higher S/N ratios of the NOx signal with emphasis on signal stability over time for robustness andmore » durability Both continuous mode and pulse mode control techniques are being evaluated. Packaging the electronics requires careful design and circuit partitioning so that only the necessary signal conditioning electronics are coupled directly in the wiring harness, while the remainder is situated within the ECM for durability and costs reasons. This task continues to be on hold due to the limitation that the definition of the interface electronics was unavailable until very late in the project. The sense element is based on the amperometric method utilizing integrated alumina and zirconia ceramics. Precious metal electrodes are used to form the integrated heater, the cell electrodes and leads. Inside the actual sense cell structure, it is first necessary to separate NOx from the remaining oxygen constituents of the exhaust, without reducing the NOx. Once separated, the NOx will be measured using a measurement cell. Development or test coupons have been used to facilitate material selection and refinement, cell, diffusion barrier, and chamber development. The sense element currently requires elaborate interconnections. To facilitate a robust durable connection, mechanical and metallurgical connections are under investigation. Materials and process refinements continue to play an important role in the development of the sensor.« less

Fiber optic sensor technology - An opportunity for smart aerospace structures

NASA Technical Reports Server (NTRS)

Heyman, J. S.; Rogowski, R. S.; Claus, R. O.

1988-01-01

Fiber optic sensors provide the opportunity for fabricating materials with internal sensors which can serve as lifetime health monitors, analogous to a central nervous system. The embedded fiber optic sensors can be interrogated by various techniques to measure internal strain, temperature, pressure, acoustic waves and other parameters indicative of structural integrity. Experiments have been conducted with composite samples with embedded sensors to measure strain using optical time domain reflectometry, modal interference and an optical phase locked loop. Fiber optic sensors have been developed to detect acoustic emission and impact damage and have been demonstrated for cure monitoring. These sensors have the potential for lifetime monitoring of structural properties, providing real time nondestructive evaluation.

Method and apparatus for phase and amplitude detection

DOEpatents

Cernosek, R.W.; Frye, G.C.; Martin, S.J.

1998-06-09

A new class of techniques has been developed which allow inexpensive application of SAW-type chemical sensor devices while retaining high sensitivity (ppm) to chemical detection. The new techniques do not require that the sensor be part of an oscillatory circuit, allowing large concentrations of, e.g., chemical vapors in air, to be accurately measured without compromising the capacity to measure trace concentrations. Such devices have numerous potential applications in environmental monitoring, from manufacturing environments to environmental restoration. 12 figs.

High magnetic field test of bismuth Hall sensors for ITER steady state magnetic diagnostic.

PubMed

Ďuran, I; Entler, S; Kohout, M; Kočan, M; Vayakis, G

2016-11-01

Performance of bismuth Hall sensors developed for the ITER steady state magnetic diagnostic was investigated for high magnetic fields in the range ±7 T. Response of the sensors to the magnetic field was found to be nonlinear particularly within the range ±1 T. Significant contribution of the planar Hall effect to the sensors output voltage causing undesirable cross field sensitivity was identified. It was demonstrated that this effect can be minimized by the optimization of the sensor geometry and alignment with the magnetic field and by the application of "current-spinning technique."

Fibre optic system for biochemical and microbiological sensing

NASA Astrophysics Data System (ADS)

Penwill, L. A.; Slater, J. H.; Hayes, N. W.; Tremlett, C. J.

2007-07-01

This poster will discuss state-of-the-art fibre optic sensors based on evanescent wave technology emphasising chemophotonic sensors for biochemical reactions and microbe detection. Devices based on antibody specificity and unique DNA sequences will be described. The development of simple sensor devices with disposable single use sensor probes will be illustrated with a view to providing cost effective field based or point of care analysis of major themes such as hospital acquired infections or bioterrorism events. This presentation will discuss the nature and detection thresholds required, the optical detection techniques investigated, results of sensor trials and the potential for wider commercial application.

A Sensor System for Detection of Hull Surface Defects

PubMed Central

Navarro, Pedro; Iborra, Andrés; Fernández, Carlos; Sánchez, Pedro; Suardíaz, Juan

2010-01-01

This paper presents a sensor system for detecting defects in ship hull surfaces. The sensor was developed to enable a robotic system to perform grit blasting operations on ship hulls. To achieve this, the proposed sensor system captures images with the help of a camera and processes them in real time using a new defect detection method based on thresholding techniques. What makes this method different is its efficiency in the automatic detection of defects from images recorded in variable lighting conditions. The sensor system was tested under real conditions at a Spanish shipyard, with excellent results. PMID:22163590

Fiber optic pressure sensors in skin-friction measurements

NASA Technical Reports Server (NTRS)

Kidwell, R.

1985-01-01

Fiber optic lever pressure sensors intended for use in a low speed wind tunnel environment were designed, constructed and tested for the measurement of normal and shear displacements associated with the pressures acting on a flat aluminum plate. On-site tests performed along with several static and dynamic measurements made have established that, with proper modifications and improvements, the design concepts are acceptable and can be utilized for their intended use. Several elastomers were investigated for use in sensors and for their incorporation into these sensors. Design and assembly techniques for probes and complete sensors were developed.

Optical fiber sensor of partial discharges in High Voltage DC experiments

NASA Astrophysics Data System (ADS)

Búa-Núñez, I.; Azcárraga-Ramos, C. G.; Posada-Román, J. E.; Garcia-Souto, J. A.

2014-05-01

A setup simulating High Voltage DC (HVDC) transformers barriers was developed to demonstrate the effectiveness of an optical fiber (OF) sensor in detecting partial discharges (PD) under these peculiar conditions. Different PD detection techniques were compared: electrical methods, and acoustic methods. Standard piezoelectric sensors (R15i-AST) and the above mentioned OF sensors were used for acoustic detection. The OF sensor was able to detect PD acoustically with a sensitivity better than the other detection methods. The multichannel instrumentation system was tested in real HVDC conditions with the aim of analyzing the behavior of the insulation (mineral oil/pressboard).

Development of an Electron-capture Technique Specific for Explosives Detection

DOT National Transportation Integrated Search

1974-07-01

This document contains information on the design, fabrication, and testing of a prototype detector specific for explosives which employs electron-capture sensors. The technique used exploits the observation that the electronegative vapors from explos...

Priorities and developments of sensors, samplers and methods for key marine biological observations.

NASA Astrophysics Data System (ADS)

Simmons, Samantha; Chavez, Francisco; Pearlman, Jay

2016-04-01

Over the last two decades or more, physical oceanography has seen a significant growth in in-situ sensors and platforms including fixed point and cable observatories, Argo floats, gliders and AUVs to supplement satellites for creating a 3-D view of the time-varying global ocean temperature and salinity structures. There are important developments recently for biogeochemists for monitoring nitrate, chemical contaminants, oxygen and pH that can now be added to these autonomous systems. Biologists are still lagging. Given the importance of biology to ocean health and the future earth, and the present reliance on humans and ships for observing species and abundance, it is paramount that new biological sensor systems be developed. Some promising sensor systems based on, but not limited to acoustic, chemical, genomic or imaging techniques, can sense from microbes to whales, are on the horizon. These techniques can be applied in situ with either real time or recorded data and can be captured and returned to the laboratory using the autonomous systems. The number of samples is limiting, requiring adaptive and smart systems. Two steps are envisioned to meeting the challenges. The first is to identify the priority biological variables to focus observation requirements and planning. The second is to address new sensors that can fill the gaps in current capabilities for biological observations. This abstract will review recent efforts to identify core biological variables for the US Integrated Ocean Observing System and address new sensors and innovations for observing these variables, particularly focused on availability and maturity of sensors.

Reconstruction of an acoustic pressure field in a resonance tube by particle image velocimetry.

PubMed

Kuzuu, K; Hasegawa, S

2015-11-01

A technique for estimating an acoustic field in a resonance tube is suggested. The estimation of an acoustic field in a resonance tube is important for the development of the thermoacoustic engine, and can be conducted employing two sensors to measure pressure. While this measurement technique is known as the two-sensor method, care needs to be taken with the location of pressure sensors when conducting pressure measurements. In the present study, particle image velocimetry (PIV) is employed instead of a pressure measurement by a sensor, and two-dimensional velocity vector images are extracted as sequential data from only a one- time recording made by a video camera of PIV. The spatial velocity amplitude is obtained from those images, and a pressure distribution is calculated from velocity amplitudes at two points by extending the equations derived for the two-sensor method. By means of this method, problems relating to the locations and calibrations of multiple pressure sensors are avoided. Furthermore, to verify the accuracy of the present method, the experiments are conducted employing the conventional two-sensor method and laser Doppler velocimetry (LDV). Then, results by the proposed method are compared with those obtained with the two-sensor method and LDV.

Data analysis and calibration for a bulk-refractive-index-compensated surface plasmon resonance affinity sensor

NASA Astrophysics Data System (ADS)

Chinowsky, Timothy M.; Yee, Sinclair S.

2002-02-01

Surface plasmon resonance (SPR) affinity sensing, the problem of bulk refractive index (RI) interference in SPR sensing, and a sensor developed to overcome this problem are briefly reviewed. The sensor uses a design based on Texas Instruments' Spreeta SPR sensor to simultaneously measure both bulk and surface RI. The bulk RI measurement is then used to compensate the surface measurement and remove the effects of bulk RI interference. To achieve accurate compensation, robust data analysis and calibration techniques are necessary. Simple linear data analysis techniques derived from measurements of the sensor response were found to provide a versatile, low noise method for extracting measurements of bulk and surface refractive index from the raw sensor data. Automatic calibration using RI gradients was used to correct the linear estimates, enabling the sensor to produce accurate data even when the sensor has a complicated nonlinear response which varies with time. The calibration procedure is described, and the factors influencing calibration accuracy are discussed. Data analysis and calibration principles are illustrated with an experiment in which sucrose and detergent solutions are used to produce changes in bulk and surface RI, respectively.

Fiber Optic Sensor Components and Systems for Smart Materials and Structures

NASA Technical Reports Server (NTRS)

Lyons, R.

1999-01-01

The general objective of the funded research effort has been the development of discrete and distributed fiber sensors and fiber optic centered opto-electronic networks for the intelligent monitoring of phenomena in various aerospace structures related to NASA Marshall specific applications. In particular, we have proposed and have been developing technologies that we believe to be readily transferrable and which involve new fabrication techniques. The associated sensors developed can be incorporated into the matrix or on the surfaces of structures for the purpose of sensing stress, strain, temperature-both low and high, pressure field variations, phase changes, and the presence of various chemical constituents.

The trade-off characteristics of acoustic and pressure sensors for the NASP

NASA Technical Reports Server (NTRS)

Winkler, Martin; Bush, Chuck

1992-01-01

Results of a trade study for the development of pressure and acoustic sensors for use on the National Aerospace Plane (NASP) are summarized. Pressure sensors are needed to operate to 100 psia; acoustic sensors are needed that can give meaningful information about a 200 dB sound pressure level (SPL) environment. Both sensors will have to operate from a high temperature of 2000 F down to absolute zero. The main conclusions of the study are the following: (1) Diaphragm materials limit minimum size and maximum frequency response attainable. (2) No transduction is available to meet all the NASP requirements with existing technology. (3) Capacitive sensors are large relative to the requirement, have limited resolution and frequency response due to noise, and cable length is limited to approximately 20 feet. (4) Eddy current sensors are large relative to the requirement and have limited cable lengths. (5) Fiber optic sensors provide the possibility for a small sensor, even though present developments do not exhibit that characteristic. The need to use sapphire at high temperature complicates the design. Present high temperature research sensors suffer from poor resolution. A significant development effort will be required to realize the potential of fiber optics. (6) Short-term development seems to favor eddy current techniques with the penalty of larger size and reduced dynamic range for acoustic sensors. (7) Long-term development may favor fiber optics with the penalties of cost, schedule, and uncertainty.

Development and evaluation of optical fiber NH3 sensors for application in air quality monitoring

NASA Astrophysics Data System (ADS)

Huang, Yu; Wieck, Lucas; Tao, Shiquan

2013-02-01

Ammonia is a major air pollutant emitted from agricultural practices. Sources of ammonia include manure from animal feeding operations and fertilizer from cropping systems. Sensor technologies with capability of continuous real time monitoring of ammonia concentration in air are needed to qualify ammonia emissions from agricultural activities and further evaluate human and animal health effects, study ammonia environmental chemistry, and provide baseline data for air quality standard. We have developed fiber optic ammonia sensors using different sensing reagents and different polymers for immobilizing sensing reagents. The reversible fiber optic sensors have detection limits down to low ppbv levels. The response time of these sensors ranges from seconds to tens minutes depending on transducer design. In this paper, we report our results in the development and evaluation of fiber optic sensor technologies for air quality monitoring. The effect of change of temperature, humidity and carbon dioxide concentration on fiber optic ammonia sensors has been investigated. Carbon dioxide in air was found not interfere the fiber optic sensors for monitoring NH3. However, the change of humidity can cause interferences to some fiber optic NH3 sensors depending on the sensor's transducer design. The sensitivity of fiber optic NH3 sensors was found depends on temperature. Methods and techniques for eliminating these interferences have been proposed.

Quartz Crystal Microbalance with Dissipation Monitoring

DTIC Science & Technology

2014-11-06

Hydroxyapatite , 10 nm, Sensors • Biotin Functionalized on Gold Sensors • His-tag Capturing Sensor QCM-D techniques provide answers about...UV/Ozone cleaner • Hydroxyapatite , 10 nm, Sensors • Biotin Functionalized on Gold Sensors • His-tag Capturing Sensor QCM-D techniques provide

Fabrications and Applications of Stimulus-Responsive Polymer Films and Patterns on Surfaces: A Review

PubMed Central

Chen, Jem-Kun; Chang, Chi-Jung

2014-01-01

In the past two decades, we have witnessed significant progress in developing high performance stimuli-responsive polymeric materials. This review focuses on recent developments in the preparation and application of patterned stimuli-responsive polymers, including thermoresponsive layers, pH/ionic-responsive hydrogels, photo-responsive film, magnetically-responsive composites, electroactive composites, and solvent-responsive composites. Many important new applications for stimuli-responsive polymers lie in the field of nano- and micro-fabrication, where stimuli-responsive polymers are being established as important manipulation tools. Some techniques have been developed to selectively position organic molecules and then to obtain well-defined patterned substrates at the micrometer or submicrometer scale. Methods for patterning of stimuli-responsive hydrogels, including photolithography, electron beam lithography, scanning probe writing, and printing techniques (microcontact printing, ink-jet printing) were surveyed. We also surveyed the applications of nanostructured stimuli-responsive hydrogels, such as biotechnology (biological interfaces and purification of biomacromoles), switchable wettability, sensors (optical sensors, biosensors, chemical sensors), and actuators. PMID:28788489

Online, In-Situ Monitoring Combustion Turbines Using Wireless Passive Ceramic Sensors

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

Gong, Xun; An, Linan; Xu, Chengying

2013-06-30

The overall objective of this project is to develop high-temperature wireless passive ceramic sensors for online, real-time monitoring combustion turbines. During this project period, we have successfully demonstrated temperature sensors up to 1300°C and pressure sensors up to 800°C. The temperature sensor is based on a high-Q-factor dielectric resonator and the pressure sensor utilizes the evanescent-mode cavity to realize a pressure-sensitive high-Q-factor resonator. Both sensors are efficiently integrated with a compact antenna. These sensors are wirelessly interrogated. The resonant frequency change corresponding to either temperature or pressure can be identified using a time-domain gating technique. The sensors realized in thismore » project can survive harsh environments characterized by high temperatures (>1000°C) and corrosive gases, owing to the excellent material properties of polymer-derived ceramics (PDCs) developed at University of Central Florida. It is anticipated that this work will significantly advance the capability of high-temperature sensor technologies and be of a great benefit to turbine industry and their customers.« less

Research and Development of Electrostatic Accelerometers for Space Science Missions at HUST.

PubMed

Bai, Yanzheng; Li, Zhuxi; Hu, Ming; Liu, Li; Qu, Shaobo; Tan, Dingyin; Tu, Haibo; Wu, Shuchao; Yin, Hang; Li, Hongyin; Zhou, Zebing

2017-08-23

High-precision electrostatic accelerometers have achieved remarkable success in satellite Earth gravity field recovery missions. Ultralow-noise inertial sensors play important roles in space gravitational wave detection missions such as the Laser Interferometer Space Antenna (LISA) mission, and key technologies have been verified in the LISA Pathfinder mission. Meanwhile, at Huazhong University of Science and Technology (HUST, China), a space accelerometer and inertial sensor based on capacitive sensors and the electrostatic control technique have also been studied and developed independently for more than 16 years. In this paper, we review the operational principle, application, and requirements of the electrostatic accelerometer and inertial sensor in different space missions. The development and progress of a space electrostatic accelerometer at HUST, including ground investigation and space verification are presented.

Research and Development of Electrostatic Accelerometers for Space Science Missions at HUST

PubMed Central

Bai, Yanzheng; Li, Zhuxi; Hu, Ming; Liu, Li; Qu, Shaobo; Tan, Dingyin; Tu, Haibo; Wu, Shuchao; Yin, Hang; Li, Hongyin; Zhou, Zebing

2017-01-01

High-precision electrostatic accelerometers have achieved remarkable success in satellite Earth gravity field recovery missions. Ultralow-noise inertial sensors play important roles in space gravitational wave detection missions such as the Laser Interferometer Space Antenna (LISA) mission, and key technologies have been verified in the LISA Pathfinder mission. Meanwhile, at Huazhong University of Science and Technology (HUST, China), a space accelerometer and inertial sensor based on capacitive sensors and the electrostatic control technique have also been studied and developed independently for more than 16 years. In this paper, we review the operational principle, application, and requirements of the electrostatic accelerometer and inertial sensor in different space missions. The development and progress of a space electrostatic accelerometer at HUST, including ground investigation and space verification are presented. PMID:28832538

Optical power-based interrogation of plasmonic tilted fiber Bragg grating biosensors

NASA Astrophysics Data System (ADS)

González-Vila, Á.; Lopez-Aldaba, A.; Kinet, D.; Mégret, P.; Lopez-Amo, M.; Caucheteur, C.

2017-04-01

Two interrogation techniques for plasmonic tilted fiber Bragg grating sensors are reported and experimentally tested. Typical interrogation methods are usually based on tracking the wavelength shift of the most sensitive cladding mode, but for biosensing applications, spectrometer-based methods can be replaced by more efficient solutions. The proposed techniques thus rely on the measurement of the induced changes in optical power. The first one consists of a properly polarized tunable laser source set to emit at the wavelength of the sensor most sensitive mode and an optical power meter to measure the transmitted response. For the second method, a uniform fiber Bragg grating is photo-inscribed beyond the sensor in such a way that its central wavelength matches the sensor most sensitive mode, acting as an optical filter. Using a LED source, light reflected backwards by this grating is partially attenuated when passing through the sensor due to plasmon wave excitation and the power changes are quantified once again with an optical power meter. A performance analysis of the techniques is carried out and they both result competitive interrogation solutions. The work thus focuses on the development of cost-effective alternatives for monitoring this kind of biosensors in practical situations.

Discrimination Method of the Volatiles from Fresh Mushrooms by an Electronic Nose Using a Trapping System and Statistical Standardization to Reduce Sensor Value Variation

PubMed Central

Fujioka, Kouki; Shimizu, Nobuo; Manome, Yoshinobu; Ikeda, Keiichi; Yamamoto, Kenji; Tomizawa, Yasuko

2013-01-01

Electronic noses have the benefit of obtaining smell information in a simple and objective manner, therefore, many applications have been developed for broad analysis areas such as food, drinks, cosmetics, medicine, and agriculture. However, measurement values from electronic noses have a tendency to vary under humidity or alcohol exposure conditions, since several types of sensors in the devices are affected by such variables. Consequently, we show three techniques for reducing the variation of sensor values: (1) using a trapping system to reduce the infering components; (2) performing statistical standardization (calculation of z-score); and (3) selecting suitable sensors. With these techniques, we discriminated the volatiles of four types of fresh mushrooms: golden needle (Flammulina velutipes), white mushroom (Agaricus bisporus), shiitake (Lentinus edodes), and eryngii (Pleurotus eryngii) among six fresh mushrooms (hen of the woods (Grifola frondosa), shimeji (Hypsizygus marmoreus) plus the above mushrooms). Additionally, we succeeded in discrimination of white mushroom, only comparing with artificial mushroom flavors, such as champignon flavor and truffle flavor. In conclusion, our techniques will expand the options to reduce variations in sensor values. PMID:24233028

Evaluating sustainable energy harvesting systems for human implantable sensors

NASA Astrophysics Data System (ADS)

AL-Oqla, Faris M.; Omar, Amjad A.; Fares, Osama

2018-03-01

Achieving most appropriate energy-harvesting technique for human implantable sensors is still challenging for the industry where keen decisions have to be performed. Moreover, the available polymeric-based composite materials are offering plentiful renewable applications that can help sustainable development as being useful for the energy-harvesting systems such as photovoltaic, piezoelectric, thermoelectric devices as well as other energy storage systems. This work presents an expert-based model capable of better evaluating and examining various available renewable energy-harvesting techniques in urban surroundings subject to various technical and economic, often conflicting, criteria. Wide evaluation criteria have been adopted in the proposed model after examining their suitability as well as ensuring the expediency and reliability of the model by worldwide experts' feedback. The model includes establishing an analytic hierarchy structure with simultaneous 12 conflicting factors to establish a systematic road map for designers to better assess such techniques for human implantable medical sensors. The energy-harvesting techniques considered were limited to Wireless, Thermoelectric, Infrared Radiator, Piezoelectric, Magnetic Induction and Electrostatic Energy Harvesters. Results have demonstrated that the best decision was in favour of wireless-harvesting technology for the medical sensors as it is preferable by most of the considered evaluation criteria in the model.

Sensor data validation and reconstruction. Phase 1: System architecture study

NASA Technical Reports Server (NTRS)

1991-01-01

The sensor validation and data reconstruction task reviewed relevant literature and selected applicable validation and reconstruction techniques for further study; analyzed the selected techniques and emphasized those which could be used for both validation and reconstruction; analyzed Space Shuttle Main Engine (SSME) hot fire test data to determine statistical and physical relationships between various parameters; developed statistical and empirical correlations between parameters to perform validation and reconstruction tasks, using a computer aided engineering (CAE) package; and conceptually designed an expert system based knowledge fusion tool, which allows the user to relate diverse types of information when validating sensor data. The host hardware for the system is intended to be a Sun SPARCstation, but could be any RISC workstation with a UNIX operating system and a windowing/graphics system such as Motif or Dataviews. The information fusion tool is intended to be developed using the NEXPERT Object expert system shell, and the C programming language.

Optical Sensors and Methods for Underwater 3D Reconstruction

PubMed Central

Massot-Campos, Miquel; Oliver-Codina, Gabriel

2015-01-01

This paper presents a survey on optical sensors and methods for 3D reconstruction in underwater environments. The techniques to obtain range data have been listed and explained, together with the different sensor hardware that makes them possible. The literature has been reviewed, and a classification has been proposed for the existing solutions. New developments, commercial solutions and previous reviews in this topic have also been gathered and considered. PMID:26694389

Rapid Development of New Protein Biosensors Utilizing Peptides Obtained via Phage Display

DTIC Science & Technology

2011-10-01

removal of loosely bound peptide or the viscosity/density change of solutions. ALT sensor operation QCM , CV and EIS measurements validated the formation...manuscript, we demonstrate this process from start to finish to create a new biosensor for the detection of ALT. Figure 6. Sensor operation. A) QCM ...peptides, peptide synthesis with a terminal thiol, QCM in-situ monitoring of peptide immobilization, and sensor detection using electrochemical techniques

[Development of sample pretreatment techniques-rapid detection coupling methods for food security analysis].

PubMed

Huang, Yichun; Ding, Weiwei; Zhang, Zhuomin; Li, Gongke

2013-07-01

This paper summarizes the recent developments of the rapid detection methods for food security, such as sensors, optical techniques, portable spectral analysis, enzyme-linked immunosorbent assay, portable gas chromatograph, etc. Additionally, the applications of these rapid detection methods coupled with sample pretreatment techniques in real food security analysis are reviewed. The coupling technique has the potential to provide references to establish the selective, precise and quantitative rapid detection methods in food security analysis.

Inferring the most probable maps of underground utilities using Bayesian mapping model

NASA Astrophysics Data System (ADS)

Bilal, Muhammad; Khan, Wasiq; Muggleton, Jennifer; Rustighi, Emiliano; Jenks, Hugo; Pennock, Steve R.; Atkins, Phil R.; Cohn, Anthony

2018-03-01

Mapping the Underworld (MTU), a major initiative in the UK, is focused on addressing social, environmental and economic consequences raised from the inability to locate buried underground utilities (such as pipes and cables) by developing a multi-sensor mobile device. The aim of MTU device is to locate different types of buried assets in real time with the use of automated data processing techniques and statutory records. The statutory records, even though typically being inaccurate and incomplete, provide useful prior information on what is buried under the ground and where. However, the integration of information from multiple sensors (raw data) with these qualitative maps and their visualization is challenging and requires the implementation of robust machine learning/data fusion approaches. An approach for automated creation of revised maps was developed as a Bayesian Mapping model in this paper by integrating the knowledge extracted from sensors raw data and available statutory records. The combination of statutory records with the hypotheses from sensors was for initial estimation of what might be found underground and roughly where. The maps were (re)constructed using automated image segmentation techniques for hypotheses extraction and Bayesian classification techniques for segment-manhole connections. The model consisting of image segmentation algorithm and various Bayesian classification techniques (segment recognition and expectation maximization (EM) algorithm) provided robust performance on various simulated as well as real sites in terms of predicting linear/non-linear segments and constructing refined 2D/3D maps.

Microwave remote sensing of soil moisture, volume 1. [Guymon, Oklahoma and Dalhart, Texas

NASA Technical Reports Server (NTRS)

Mcfarland, M. J. (Principal Investigator); Theis, S. W.; Rosenthal, W. D.; Jones, C. L.

1982-01-01

Multifrequency sensor data from NASA's C-130 aircraft were used to determine which of the all weather microwave sensors demonstrated the highest correlation to surface soil moisture over optimal bare soil conditions, and to develop and test techniques which use visible/infrared sensors to compensate for the vegetation effect in this sensor's response to soil moisture. The L-band passive microwave radiometer was found to be the most suitable single sensor system to estimate soil moisture over bare fields. The perpendicular vegetation index (PVI) as determined from the visible/infrared sensors was useful as a measure of the vegetation effect on the L-band radiometer response to soil moisture. A linear equation was developed to estimate percent field capacity as a function of L-band emissivity and the vegetation index. The prediction algorithm improves the estimation of moisture significantly over predictions from L-band emissivity alone.

A versatile fibre optic sensor interrogation system for the Ariane Launcher based on an electro-optically tuneable laser diode

NASA Astrophysics Data System (ADS)

Plattner, M. P.; Hirth, F.; Müller, M. S.; Hoffmann, L.; Buck, T. C.; Koch, A. W.

2017-11-01

Availability of reliable flight sensor data and knowledge of the structural behaviour are essential for safe operation of the Ariane launcher. The Ariane launcher is currently monitored by hundreds of electric sensors during test and qualification. Fibre optic sensors are regarded as a potential technique to overcome limitations of recent monitoring systems for the Ariane launcher [1]. These limitations include cumbersome application of sensors and harness as well as a very limited degree of distributed sensing capability. But, in order to exploit the various advantages of fibre optic sensors (high degree of multiplexing, distributed sensing capability, lower mass impact, etc.) dedicated measurement systems have to be developed and investigated. State-of-the-art fibre optic measurement systems often use free beam setups making them bulky and sensitive to vibration impact. Therefore a new measurement system is developed as part of the ESAstudy [2].

Infrared-fiber-optic fire sensor developments - Role of measurement uncertainty in evaluation of background limited range. [in spacecraft safety

NASA Technical Reports Server (NTRS)

Tapphorn, Ralph M.; Kays, Randy; Porter, Alan

1989-01-01

Fire-detector systems based on distributed infrared fiber-sensors have been investigated for potential applications in the aerospace industry. Responsivities to blackbody and flame radiations were measured with various design configurations of an infrared fiber-optic sensor. Signal processing techniques were also investigated, and the results show significant differences in the fire-sensor performance depending on the design configuration. Measurement uncertainties were used to determine the background-limited ranges for the various fire-sensor concepts, and the probability of producing false alarms caused by fluctuations in the background signals were determined using extreme probability theory. The results of the research show that infrared fiber-optic fire sensors are feasible for application on manned spacecraft; however, additional development work will be required to eliminate false alarms caused by high temperature objects such as incandescent lamps.

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.

Optical fiber sensors measurement system and special fibers improvement

NASA Astrophysics Data System (ADS)

Jelinek, Michal; Hrabina, Jan; Hola, Miroslava; Hucl, Vaclav; Cizek, Martin; Rerucha, Simon; Lazar, Josef; Mikel, Bretislav

2017-06-01

We present method for the improvement of the measurement accuracy in the optical frequency spectra measurements based on tunable optical filters. The optical filter was used during the design and realization of the measurement system for the inspection of the fiber Bragg gratings. The system incorporates a reference block for the compensation of environmental influences, an interferometric verification subsystem and a PC - based control software implemented in LabView. The preliminary experimental verification of the measurement principle and the measurement system functionality were carried out on a testing rig with a specially prepared concrete console in the UJV Řež. The presented system is the laboratory version of the special nuclear power plant containment shape deformation measurement system which was installed in the power plant Temelin during last year. On the base of this research we started with preparation other optical fiber sensors to nuclear power plants measurement. These sensors will be based on the microstructured and polarization maintaining optical fibers. We started with development of new methods and techniques of the splicing and shaping optical fibers. We are able to made optical tapers from ultra-short called adiabatic with length around 400 um up to long tapers with length up to 6 millimeters. We developed new techniques of splicing standard Single Mode (SM) and Multimode (MM) optical fibers and splicing of optical fibers with different diameters in the wavelength range from 532 to 1550 nm. Together with development these techniques we prepared other techniques to splicing and shaping special optical fibers like as Polarization-Maintaining (PM) or hollow core Photonic Crystal Fiber (PCF) and theirs cross splicing methods with focus to minimalize backreflection and attenuation. The splicing special optical fibers especially PCF fibers with standard telecommunication and other SM fibers can be done by our developed techniques. Adjustment of the splicing process has to be prepared for any new optical fibers and new fibers combinations. The splicing of the same types of fibers from different manufacturers can be adjusted by several tested changes in the splicing process. We are able to splice PCF with standard telecommunication fiber with attenuation up to 2 dB. The method is also presented. Development of these new techniques and methods of the optical fibers splicing are made with respect to using these fibers to another research and development in the field of optical fibers sensors, laser frequency stabilization and laser interferometry based on optical fibers. Especially for the field of laser frequency stabilization we developed and present new techniques to closing microstructured fibers with gases inside.

A High-Speed Vision-Based Sensor for Dynamic Vibration Analysis Using Fast Motion Extraction Algorithms.

PubMed

Zhang, Dashan; Guo, Jie; Lei, Xiujun; Zhu, Changan

2016-04-22

The development of image sensor and optics enables the application of vision-based techniques to the non-contact dynamic vibration analysis of large-scale structures. As an emerging technology, a vision-based approach allows for remote measuring and does not bring any additional mass to the measuring object compared with traditional contact measurements. In this study, a high-speed vision-based sensor system is developed to extract structure vibration signals in real time. A fast motion extraction algorithm is required for this system because the maximum sampling frequency of the charge-coupled device (CCD) sensor can reach up to 1000 Hz. Two efficient subpixel level motion extraction algorithms, namely the modified Taylor approximation refinement algorithm and the localization refinement algorithm, are integrated into the proposed vision sensor. Quantitative analysis shows that both of the two modified algorithms are at least five times faster than conventional upsampled cross-correlation approaches and achieve satisfactory error performance. The practicability of the developed sensor is evaluated by an experiment in a laboratory environment and a field test. Experimental results indicate that the developed high-speed vision-based sensor system can extract accurate dynamic structure vibration signals by tracking either artificial targets or natural features.

An adaptive Hidden Markov Model for activity recognition based on a wearable multi-sensor device

USDA-ARS?s Scientific Manuscript database

Human activity recognition is important in the study of personal health, wellness and lifestyle. In order to acquire human activity information from the personal space, many wearable multi-sensor devices have been developed. In this paper, a novel technique for automatic activity recognition based o...

Multimodal Teaching Analytics: Automated Extraction of Orchestration Graphs from Wearable Sensor Data

ERIC Educational Resources Information Center

Prieto, L. P.; Sharma, K.; Kidzinski, L.; Rodríguez-Triana, M. J.; Dillenbourg, P.

2018-01-01

The pedagogical modelling of everyday classroom practice is an interesting kind of evidence, both for educational research and teachers' own professional development. This paper explores the usage of wearable sensors and machine learning techniques to automatically extract orchestration graphs (teaching activities and their social plane over time)…

HIGHLY SELECTIVE SENSORS FOR CHEMICAL AND BIOLOGICAL WARFARE AGENTS, INSECTICIDES AND VOCS BASED ON A MOLECULAR SURFACE IMPRINTING TECHNIQUE

EPA Science Inventory

Abstract was given as an oral platform presentation at the Pittsburgh Conference, Orlando FL (March 5-9, 2006). Research described is the development of sensors based on molecular surface imprinting. Applications include the monitoring of chemical and biological agents and inse...

Ultrasonic techniques for measuring physical properties of fluids in harsh environments

NASA Astrophysics Data System (ADS)

Pantea, Cristian

Ultrasonic-based measurement techniques, either in the time domain or in the frequency domain, include a wide range of experimental methods for investigating physical properties of materials. This discussion is specifically focused on ultrasonic methods and instrumentation development for the determination of liquid properties at conditions typically found in subsurface environments (in the U.S., more than 80% of total energy needs are provided by subsurface energy sources). Such sensors require materials that can withstand harsh conditions of high pressure, high temperature and corrosiveness. These include the piezoelectric material, electrically conductive adhesives, sensor housings/enclosures, and the signal carrying cables, to name a few. A complete sensor package was developed for operation at high temperatures and pressures characteristic to geothermal/oil-industry reservoirs. This package is designed to provide real-time, simultaneous measurements of multiple physical parameters, such as temperature, pressure, salinity and sound speed. The basic principle for this sensor's operation is an ultrasonic frequency domain technique, combined with transducer resonance tracking. This multipurpose acoustic sensor can be used at depths of several thousand meters, temperatures up to 250 °C, and in a very corrosive environment. In the context of high precision measurement of sound speed, the determination of acoustic nonlinearity of liquids will also be discussed, using two different approaches: (i) the thermodynamic method, in which precise and accurate frequency domain sound speed measurements are performed at high pressure and high temperature, and (ii) a modified finite amplitude method, requiring time domain measurements of the second harmonic at room temperature. Efforts toward the development of an acoustic source of collimated low-frequency (10-150 kHz) beam, with applications in imaging, will also be presented.

Step-gate polysilicon nanowires field effect transistor compatible with CMOS technology for label-free DNA biosensor.

PubMed

Wenga, G; Jacques, E; Salaün, A-C; Rogel, R; Pichon, L; Geneste, F

2013-02-15

Currently, detection of DNA hybridization using fluorescence-based detection technique requires expensive optical systems and complex bioinformatics tools. Hence, the development of new low cost devices that enable direct and highly sensitive detection stimulates a lot of research efforts. Particularly, devices based on silicon nanowires are emerging as ultrasensitive electrical sensors for the direct detection of biological species thanks to their high surface to volume ratio. In this study, we propose innovative devices using step-gate polycrystalline silicon nanowire FET (poly-Si NW FETs), achieved with simple and low cost fabrication process, and used as ultrasensitive electronic sensor for DNA hybridization. The poly-SiNWs are synthesized using the sidewall spacer formation technique. The detailed fabrication procedure for a step-gate NWFET sensor is described in this paper. No-complementary and complementary DNA sequences were clearly discriminated and detection limit to 1 fM range is observed. This first result using this nano-device is promising for the development of low cost and ultrasensitive polysilicon nanowires based DNA sensors compatible with the CMOS technology. Copyright © 2012 Elsevier B.V. All rights reserved.

A qualitative review for wireless health monitoring system

NASA Astrophysics Data System (ADS)

Arshad, Atika; Fadzil Ismail, Ahmad; Khan, Sheroz; Zahirul Alam, A. H. M.; Tasnim, Rumana; Samnan Haider, Syed; Shobaki, Mohammed M.; Shahid, Zeeshan

2013-12-01

A proliferating interest has been being observed over the past years in accurate wireless system development in order to monitor incessant human activities in health care centres. Furthermore because of the swelling number of elderly population and the inadequate number of competent staffs for nursing homes there is a big market petition for health care monitoring system. In order to detect human researchers developed different methods namely which include Field Identification technique, Visual Sensor Network, radar detection, e-mobile techniques and so on. An all-encompassing overview of the non-wired human detection application advancement is presented in this paper. Inductive links are used for human detection application while wiring an electronic system has become impractical in recent times. Keeping in mind the shortcomings, an Inductive Intelligent Sensor (IIS) has been proposed as a novel human monitoring system for future implementation. The proposed sensor works towards exploring the signature signals of human body movement and size. This proposed sensor is fundamentally based on inductive loop that senses the presence and a passing human resulting an inductive change.

Investigating the use of multi-point coupling for single-sensor bearing estimation in one direction

NASA Astrophysics Data System (ADS)

Woolard, Americo G.; Phoenix, Austin A.; Tarazaga, Pablo A.

2018-04-01

Bearing estimation of radially propagating symmetric waves in solid structures typically requires a minimum of two sensors. As a test specimen, this research investigates the use of multi-point coupling to provide directional inference using a single-sensor. By this provision, the number of sensors required for localization can be reduced. A finite-element model of a beam is constructed with a symmetrically placed bipod that has asymmetric joint-stiffness properties. Impulse loading is applied at different points along the beam, and measurements are taken from the apex of the bipod. A technique is developed to determine the direction-of-arrival of the propagating wave. The accuracy when using the bipod with the developed technique is compared against results gathered without the bipod and measuring from an asymmetric location along the beam. The results show 92% accuracy when the bipod is used, compared to 75% when measuring without the bipod from an asymmetric location. A geometry investigation finds the best accuracy results when one leg of the bipod has a low stiffness and a large diameter relative to the other leg.

Flight data acquisition methodology for validation of passive ranging algorithms for obstacle avoidance

NASA Technical Reports Server (NTRS)

Smith, Phillip N.

1990-01-01

The automation of low-altitude rotorcraft flight depends on the ability to detect, locate, and navigate around obstacles lying in the rotorcraft's intended flightpath. Computer vision techniques provide a passive method of obstacle detection and range estimation, for obstacle avoidance. Several algorithms based on computer vision methods have been developed for this purpose using laboratory data; however, further development and validation of candidate algorithms require data collected from rotorcraft flight. A data base containing low-altitude imagery augmented with the rotorcraft and sensor parameters required for passive range estimation is not readily available. Here, the emphasis is on the methodology used to develop such a data base from flight-test data consisting of imagery, rotorcraft and sensor parameters, and ground-truth range measurements. As part of the data preparation, a technique for obtaining the sensor calibration parameters is described. The data base will enable the further development of algorithms for computer vision-based obstacle detection and passive range estimation, as well as provide a benchmark for verification of range estimates against ground-truth measurements.

Development and Evaluation of A Novel and Cost-Effective Approach for Low-Cost NO₂ Sensor Drift Correction.

PubMed

Sun, Li; Westerdahl, Dane; Ning, Zhi

2017-08-19

Emerging low-cost gas sensor technologies have received increasing attention in recent years for air quality measurements due to their small size and convenient deployment. However, in the diverse applications these sensors face many technological challenges, including sensor drift over long-term deployment that cannot be easily addressed using mathematical correction algorithms or machine learning methods. This study aims to develop a novel approach to auto-correct the drift of commonly used electrochemical nitrogen dioxide (NO₂) sensor with comprehensive evaluation of its application. The impact of environmental factors on the NO₂ electrochemical sensor in low-ppb concentration level measurement was evaluated in laboratory and the temperature and relative humidity correction algorithm was evaluated. An automated zeroing protocol was developed and assessed using a chemical absorbent to remove NO₂ as a means to perform zero correction in varying ambient conditions. The sensor system was operated in three different environments in which data were compared to a reference NO₂ analyzer. The results showed that the zero-calibration protocol effectively corrected the observed drift of the sensor output. This technique offers the ability to enhance the performance of low-cost sensor based systems and these findings suggest extension of the approach to improve data quality from sensors measuring other gaseous pollutants in urban air.

Escape and evade control policies for ensuring the physical security of nonholonomic, ground-based, unattended mobile sensor nodes

NASA Astrophysics Data System (ADS)

Mascarenas, David; Stull, Christopher; Farrar, Charles

2011-06-01

In order to realize the wide-scale deployment of high-endurance, unattended mobile sensing technologies, it is vital to ensure the self-preservation of the sensing assets. Deployed mobile sensor nodes face a variety of physical security threats including theft, vandalism and physical damage. Unattended mobile sensor nodes must be able to respond to these threats with control policies that facilitate escape and evasion to a low-risk state. In this work the Precision Immobilization Technique (PIT) problem has been considered. The PIT maneuver is a technique that a pursuing, car-like vehicle can use to force a fleeing vehicle to abruptly turn ninety degrees to the direction of travel. The abrupt change in direction generally causes the fleeing driver to lose control and stop. The PIT maneuver was originally developed by law enforcement to end vehicular pursuits in a manner that minimizes damage to the persons and property involved. It is easy to imagine that unattended autonomous convoys could be targets of this type of action by adversarial agents. This effort focused on developing control policies unattended mobile sensor nodes could employ to escape, evade and recover from PIT-maneuver-like attacks. The development of these control policies involved both simulation as well as small-scale experimental testing. The goal of this work is to be a step toward ensuring the physical security of unattended sensor node assets.

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

NASA Astrophysics Data System (ADS)

Mao, Lei; Jackson, Lisa

2016-10-01

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

Novel Modified Optical Fibers for High Temperature In-Situ Miniaturized Gas Sensors in Advanced Fossil Energy Systems

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

Pickrell, Gary; Scott, Brian

2014-06-30

This report covers the technical progress on the program “Novel Modified Optical Fibers for High Temperature In-Situ Miniaturized Gas Sensors in Advanced Fossil Energy Systems”, funded by the National Energy Technology Laboratory of the U.S. Department of Energy, and performed by the Materials Science & Engineering and Electrical & Computer Engineering Departments at Virginia Tech, and summarizes technical progress from July 1st, 2005 –June 30th, 2014. The objective of this program was to develop novel fiber materials for high temperature gas sensors based on evanescent wave absorption in optical fibers. This project focused on two primary areas: the study ofmore » a sapphire photonic crystal fiber (SPCF) for operation at high temperature and long wavelengths, and a porous glass based fiber optic sensor for gas detection. The sapphire component of the project focused on the development of a sapphire photonic crystal fiber, modeling of the new structures, fabrication of the optimal structure, development of a long wavelength interrogation system, testing of the optical properties, and gas and temperature testing of the final sensor. The fabrication of the 6 rod SPCF gap bundle (diameter of 70μm) with a hollow core was successfully constructed with lead-in and lead-out 50μm diameter fiber along with transmission and gas detection testing. Testing of the sapphire photonic crystal fiber sensor capabilities with the developed long wavelength optical system showed the ability to detect CO 2 at or below 1000ppm at temperatures up to 1000°C. Work on the porous glass sensor focused on the development of a porous clad solid core optical fiber, a hollow core waveguide, gas detection capabilities at room and high temperature, simultaneous gas species detection, suitable joining technologies for the lead-in and lead-out fibers and the porous sensor, sensor system sensitivity improvement, signal processing improvement, relationship between pore structure and fiber geometry to optical properties, and the development of a sensor packaging prototype for laboratory testing. Analysis and experiments determined that a bonding technique using a CO 2 laser is the most suitable joining technique. Pore morphology alteration showed that transmission improved with increasing annealing temperature (producing smaller pores), while the sensor response time increased and the mechanical strength decreased with increasing annealing temperature. Software was developed for data acquisition and signal processing to collect and interpret spectral gas absorption data. Gas detection on porous glass sensors was completed and the detection limit was evaluated using acetylene and was found to be around 1- 200ppm. A complete materials package for porous glass sensors was manufactured for testing.« less

Smart wheelchair: integration of multiple sensors

NASA Astrophysics Data System (ADS)

Gassara, H. E.; Almuhamed, S.; Moukadem, A.; Schacher, L.; Dieterlen, A.; Adolphe, D.

2017-10-01

The aim of the present work is to develop a smart wheelchair by integrating multiple sensors for measuring user’s physiological signals and subsequently transmitting and monitoring the treated signals to the user, a designated person or institution. Among other sensors, force, accelerometer, and temperature sensors are successfully integrated within both the backrest and the seat cushions of the wheelchair; while a pulse sensor is integrated within the armrest. The pulse sensor is connected to an amplification circuit board that is, in turn, placed within the armrest. The force and temperature sensors are integrated into a textile cover of the cushions by means of embroidery and sewing techniques. The signal from accelerometer is transmitted through Wi-Fi connection. The electrical connections needed for power supplying of sensors are made by embroidered conductive threads.

Growth of single wall carbon nanotubes using PECVD technique: An efficient chemiresistor gas sensor

NASA Astrophysics Data System (ADS)

Lone, Mohd Yaseen; Kumar, Avshish; Husain, Samina; Zulfequar, M.; Harsh; Husain, Mushahid

2017-03-01

In this work, the uniform and vertically aligned single wall carbon nanotubes (SWCNTs) have been grown on Iron (Fe) deposited Silicon (Si) substrate by plasma enhanced chemical vapor deposition (PECVD) technique at very low temperature of 550 °C. The as-grown samples of SWCNTS were characterized by field emission scanning electron microscope (FESEM), high resolution transmission electron microscope (HRTEM) and Raman spectrometer. SWCNT based chemiresistor gas sensing device was fabricated by making the proper gold contacts on the as-grown SWCNTs. The electrical conductance and sensor response of grown SWCNTs have been investigated. The fabricated SWCNT sensor was exposed to ammonia (NH3) gas at 200 ppm in a self assembled apparatus. The sensor response was measured at room temperature which was discussed in terms of adsorption of NH3 gas molecules on the surface of SWCNTs. The achieved results are used to develope a miniaturized gas sensor device for monitoring and control of environment pollutants.

Detection of coffee flavour ageing by solid-phase microextraction/surface acoustic wave sensor array technique (SPME/SAW).

PubMed

Barié, Nicole; Bücking, Mark; Stahl, Ullrich; Rapp, Michael

2015-06-01

The use of polymer coated surface acoustic wave (SAW) sensor arrays is a very promising technique for highly sensitive and selective detection of volatile organic compounds (VOCs). We present new developments to achieve a low cost sensor setup with a sampling method enabling the highly reproducible detection of volatiles even in the ppb range. Since the VOCs of coffee are well known by gas chromatography (GC) research studies, the new sensor array was tested for an easy assessable objective: coffee ageing during storage. As reference method these changes were traced with a standard GC/FID set-up, accompanied by sensory panellists. The evaluation of GC data showed a non-linear characteristic for single compound concentrations as well as for total peak area values, disabling prediction of the coffee age. In contrast, the new SAW sensor array demonstrates a linear dependency, i.e. being capable to show a dependency between volatile concentration and storage time. Copyright © 2014 Elsevier Ltd. All rights reserved.

Smart bi-metallic perovskite nanofibers as selective and reusable sensors of nano-level concentrations of non-steroidal anti-inflammatory drugs.

PubMed

Mohamed, Mona A; Hasan, Menna M; Abdullah, Ibrahim H; Abdellah, Ahmed M; Yehia, Ali M; Ahmed, Nashaat; Abbas, Walaa; Allam, Nageh K

2018-08-01

A strategy for trace-level carbon-based electrochemical sensors is investigated via exploring the interesting properties of BaNb 2 O 6 nanofibers (NFs). Utilizing adsorptive stripping square wave voltammetry (ASSWV), an electrochemical sensing platform was developed based on BaNb 2 O 6 nanofibers-modified carbon paste electrode (CPE) for the sensitive detection of lornoxicam (LOR). Different techniques were used to characterize the fabricated BaNb 2 O 6 perovskite NFs. The obtained data show the feasibility to electro-oxidize LOR and paracetamol (PAR) on the surface of the fabricated sensor. The amount of nanofiber and testing conditions were optimized using response surface methodology and ASSWV technique. The optimized BaNb 2 O 6 /CPE sensor exhibits low detection limit of 6.39 × 10 -10 mol L -1 , even in the presence of the co-formulated drug paracetamol (PAR). The sensor was successfully applied for biological applications. Copyright © 2018 Elsevier B.V. All rights reserved.

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.

Fiber Optic Thermal Detection of Composite Delaminations

NASA Technical Reports Server (NTRS)

Wu, Meng-Chou; Winfree, William P.

2011-01-01

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

Ultrasonic thermometry using pulse techniques.

NASA Technical Reports Server (NTRS)

Lynnworth, L. C.; Carnevale, E. H.

1972-01-01

Ultrasonic pulse techniques have been developed which, when applied to inert gases, provide temperature measurements up to 8000 K. The response time can be less than 1 msec. This is a significant feature in studying shock-heated or combusting gases. Using a momentary contact coupling technique, temperature has been measured inside steel from 300 to 1500 K. Thin-wire sensors have been used above 2000 K in nuclear and industrial applications where conditions preclude the use of thermocouples, resistance devices, or optical pyrometers. At 2500 K, temperature sensitivity of 0.1% is obtained in Re wire sensors 5 cm long by timing five round trips with an electronic instrument that resolves the time interval between selected echoes to 0.1 microsec. Sensors have been operated at rotational speeds over 2000 rpm and in noisy environments. Temperature profiling of up to ten regions using only a single guided path or beam has also been accomplished.

A modular optical sensor

NASA Astrophysics Data System (ADS)

Conklin, John Albert

This dissertation presents the design of a modular, fiber-optic sensor and the results obtained from testing the modular sensor. The modular fiber-optic sensor is constructed in such manner that the sensor diaphragm can be replaced with different configurations to detect numerous physical phenomena. Additionally, different fiber-optic detection systems can be attached to the sensor. Initially, the modular sensor was developed to be used by university of students to investigate realistic optical sensors and detection systems to prepare for advance studies of micro-optical mechanical systems (MOMS). The design accomplishes this by doing two things. First, the design significantly lowers the costs associated with studying optical sensors by modularizing the sensor design. Second, the sensor broadens the number of physical phenomena that students can apply optical sensing techniques to in a fiber optics sensor course. The dissertation is divided into seven chapters covering the historical development of fiber-optic sensors, a theoretical overview of fiber-optic sensors, the design, fabrication, and the testing of the modular sensor developed in the course of this work. Chapter 1 discusses, in detail, how this dissertation is organized and states the purpose of the dissertation. Chapter 2 presents an historical overview of the development of optical fibers, optical pressure sensors, and fibers, optical pressure sensors, and optical microphones. Chapter 3 reviews the theory of multi-fiber optic detection systems, optical microphones, and pressure sensors. Chapter 4 presents the design details of the modular, optical sensor. Chapter 5 delves into how the modular sensor is fabricated and how the detection systems are constructed. Chapter 6 presents the data collected from the microphone and pressure sensor configurations of the modular sensor. Finally, Chapter 7 discusses the data collected and draws conclusions about the design based on the data collected. Chapter 7 also presents future work needed to expand the functionality and utility of the modular sensor.

Nearest neighbor imputation using spatial–temporal correlations in wireless sensor networks

PubMed Central

Li, YuanYuan; Parker, Lynne E.

2016-01-01

Missing data is common in Wireless Sensor Networks (WSNs), especially with multi-hop communications. There are many reasons for this phenomenon, such as unstable wireless communications, synchronization issues, and unreliable sensors. Unfortunately, missing data creates a number of problems for WSNs. First, since most sensor nodes in the network are battery-powered, it is too expensive to have the nodes retransmit missing data across the network. Data re-transmission may also cause time delays when detecting abnormal changes in an environment. Furthermore, localized reasoning techniques on sensor nodes (such as machine learning algorithms to classify states of the environment) are generally not robust enough to handle missing data. Since sensor data collected by a WSN is generally correlated in time and space, we illustrate how replacing missing sensor values with spatially and temporally correlated sensor values can significantly improve the network’s performance. However, our studies show that it is important to determine which nodes are spatially and temporally correlated with each other. Simple techniques based on Euclidean distance are not sufficient for complex environmental deployments. Thus, we have developed a novel Nearest Neighbor (NN) imputation method that estimates missing data in WSNs by learning spatial and temporal correlations between sensor nodes. To improve the search time, we utilize a kd-tree data structure, which is a non-parametric, data-driven binary search tree. Instead of using traditional mean and variance of each dimension for kd-tree construction, and Euclidean distance for kd-tree search, we use weighted variances and weighted Euclidean distances based on measured percentages of missing data. We have evaluated this approach through experiments on sensor data from a volcano dataset collected by a network of Crossbow motes, as well as experiments using sensor data from a highway traffic monitoring application. Our experimental results show that our proposed 𝒦-NN imputation method has a competitive accuracy with state-of-the-art Expectation–Maximization (EM) techniques, while using much simpler computational techniques, thus making it suitable for use in resource-constrained WSNs. PMID:28435414

The Design and Development of Fluorescent Nano-Optodes for in Vivo Glucose Monitoring

PubMed Central

Balaconis, Mary K.; Billingsley, Kelvin; Dubach, J. Matthew; Cash, Kevin J.; Clark, Heather A.

2011-01-01

Background The advent of fluorescent nanosensors has enabled intracellular monitoring of several physiological analytes, which was previously not possible with molecular dyes or other invasive techniques. We have extended the capability of these sensors to include the detection of small molecules with the development of glucose-sensitive nano-optodes. Herein, we discuss the design and development of glucose-sensitive nano-optodes, which have been proven functional both in vitro and in vivo. Methods Throughout the design process, each of the sensor formulations was evaluated based on their response to changes in glucose levels. The percent change in signal, sensor reversibility, and the overall fluorescence intensity were the specific parameters used to assess each formulation. Results A hydrophobic boronic acid was selected that yielded a fully reversible fluorescence response to glucose in accordance with the sensor mechanism. The change in fluorescence signal in response to glucose was approximately 11%. The use of different additives or chromophores did not improve the response; however, modifications to the plasticized polymeric membrane extended sensor lifetime. Conclusions Sensors were developed that yielded a dynamic response to glucose and through further modification of the components, sensor lifetime was improved. By following specific design criteria for the macrosensors, the sensors were miniaturized into nano-optodes that track changes in glucose levels in vivo. PMID:21303627

The design and development of fluorescent nano-optodes for in vivo glucose monitoring.

PubMed

Balaconis, Mary K; Billingsley, Kelvin; Dubach, Matthew J; Cash, Kevin J; Clark, Heather A

2011-01-01

The advent of fluorescent nanosensors has enabled intracellular monitoring of several physiological analytes, which was previously not possible with molecular dyes or other invasive techniques. We have extended the capability of these sensors to include the detection of small molecules with the development of glucose-sensitive nano-optodes. Herein, we discuss the design and development of glucose-sensitive nano-optodes, which have been proven functional both in vitro and in vivo. Throughout the design process, each of the sensor formulations was evaluated based on their response to changes in glucose levels. The percent change in signal, sensor reversibility, and the overall fluorescence intensity were the specific parameters used to assess each formulation. A hydrophobic boronic acid was selected that yielded a fully reversible fluorescence response to glucose in accordance with the sensor mechanism. The change in fluorescence signal in response to glucose was approximately 11%. The use of different additives or chromophores did not improve the response; however, modifications to the plasticized polymeric membrane extended sensor lifetime. Sensors were developed that yielded a dynamic response to glucose and through further modification of the components, sensor lifetime was improved. By following specific design criteria for the macrosensors, the sensors were miniaturized into nano-optodes that track changes in glucose levels in vivo. © 2010 Diabetes Technology Society.

Recent advances in electronic nose techniques for monitoring of fermentation process.

PubMed

Jiang, Hui; Zhang, Hang; Chen, Quansheng; Mei, Congli; Liu, Guohai

2015-12-01

Microbial fermentation process is often sensitive to even slight changes of conditions that may result in unacceptable end-product quality. Thus, the monitoring of the process is critical for discovering unfavorable deviations as early as possible and taking the appropriate measures. However, the use of traditional analytical techniques is often time-consuming and labor-intensive. In this sense, the most effective way of developing rapid, accurate and relatively economical method for quality assurance in microbial fermentation process is the use of novel chemical sensor systems. Electronic nose techniques have particular advantages in non-invasive monitoring of microbial fermentation process. Therefore, in this review, we present an overview of the most important contributions dealing with the quality control in microbial fermentation process using the electronic nose techniques. After a brief description of the fundamentals of the sensor techniques, some examples of potential applications of electronic nose techniques monitoring are provided, including the implementation of control strategies and the combination with other monitoring tools (i.e. sensor fusion). Finally, on the basis of the review, the electronic nose techniques are critically commented, and its strengths and weaknesses being highlighted. In addition, on the basis of the observed trends, we also propose the technical challenges and future outlook for the electronic nose techniques.

Load monitoring using a calibrated piezo diaphragm based impedance strain sensor and wireless sensor network in real time

NASA Astrophysics Data System (ADS)

Gopal Madhav Annamdas, Venu; Kiong Soh, Chee

2017-04-01

The last decade has seen the use of various wired-wireless and contact-contactless sensors in several structural health monitoring (SHM) techniques. Most SHM sensors that are predominantly used for strain measurements may be ineffective for damage detection and vice versa, indicating the uniapplicability of these sensors. However, piezoelectric (PE)-based macro fiber composite (MFC) and lead zirconium titanate (PZT) sensors have been on the rise in SHM, vibration and damping control, etc, due to their superior actuation and sensing abilities. These PE sensors have created much interest for their multi-applicability in various technologies such as electromechanical impedance (EMI)-based SHM. This research employs piezo diaphragms, a cheaper alternative to several expensive types of PZT/MFC sensors for the EMI technique. These piezo diaphragms were validated last year for their applicability in damage detection using the frequency domain. Here we further validate their applicability in strain monitoring using the real time domain. Hence, these piezo diaphragms can now be classified as PE sensors and used with PZT and MFC sensors in the EMI technique for monitoring damage and loading. However, no single technique or single type of sensor will be sufficient for large SHM, thus requiring the necessary deployment of more than one technique with different types of sensors such as a piezoresistive strain gauge based wireless sensor network for strain measurements to complement the EMI technique. Furthermore, we present a novel procedure of converting a regular PE sensor in the ‘frequency domain’ to ‘real time domain’ for strain applications.

Handheld and mobile hyperspectral imaging sensors for wide-area standoff detection of explosives and chemical warfare agents

NASA Astrophysics Data System (ADS)

Gomer, Nathaniel R.; Gardner, Charles W.; Nelson, Matthew P.

2016-05-01

Hyperspectral imaging (HSI) is a valuable tool for the investigation and analysis of targets in complex background with a high degree of autonomy. HSI is beneficial for the detection of threat materials on environmental surfaces, where the concentration of the target of interest is often very low and is typically found within complex scenery. Two HSI techniques that have proven to be valuable are Raman and shortwave infrared (SWIR) HSI. Unfortunately, current generation HSI systems have numerous size, weight, and power (SWaP) limitations that make their potential integration onto a handheld or field portable platform difficult. The systems that are field-portable do so by sacrificing system performance, typically by providing an inefficient area search rate, requiring close proximity to the target for screening, and/or eliminating the potential to conduct real-time measurements. To address these shortcomings, ChemImage Sensor Systems (CISS) is developing a variety of wide-field hyperspectral imaging systems. Raman HSI sensors are being developed to overcome two obstacles present in standard Raman detection systems: slow area search rate (due to small laser spot sizes) and lack of eye-safety. SWIR HSI sensors have been integrated into mobile, robot based platforms and handheld variants for the detection of explosives and chemical warfare agents (CWAs). In addition, the fusion of these two technologies into a single system has shown the feasibility of using both techniques concurrently to provide higher probability of detection and lower false alarm rates. This paper will provide background on Raman and SWIR HSI, discuss the applications for these techniques, and provide an overview of novel CISS HSI sensors focused on sensor design and detection results.

Development of analysis techniques for remote sensing of vegetation resources

NASA Technical Reports Server (NTRS)

Draeger, W. C.

1972-01-01

Various data handling and analysis techniques are summarized for evaluation of ERTS-A and supporting high flight imagery. These evaluations are concerned with remote sensors applied to wildland and agricultural vegetation resource inventory problems. Monitoring California's annual grassland, automatic texture analysis, agricultural ground data collection techniques, and spectral measurements are included.

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.

Performance capabilities of a JPL dual-arm advanced teleoperation system

NASA Technical Reports Server (NTRS)

Szakaly, Z. F.; Bejczy, A. K.

1991-01-01

The system comprises: (1) two PUMA 560 robot arms, each equipped with the latest JPL developed smart hands which contain 3-D force/moment and grasp force sensors; (2) two general purpose force reflecting hand controllers; (3) a NS32016 microprocessors based distributed computing system together with JPL developed universal motor controllers; (4) graphics display of sensor data; (5) capabilities for time delay experiments; and (6) automatic data recording capabilities. Several different types of control modes are implemented on this system using different feedback control techniques. Some of the control modes and the related feedback control techniques are described, and the achievable control performance for tracking position and force trajectories are reported. The interaction between position and force trajectory tracking is illustrated. The best performance is obtained by using a novel, task space error feedback technique.

Microwave Readout Techniques for Very Large Arrays of Nuclear Sensors

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

Ullom, Joel

During this project, we transformed the use of microwave readout techniques for nuclear sensors from a speculative idea to reality. The core of the project consisted of the development of a set of microwave electronics able to generate and process large numbers of microwave tones. The tones can be used to probe a circuit containing a series of electrical resonances whose frequency locations and widths depend on the state of a network of sensors, with one sensor per resonance. The amplitude and phase of the tones emerging from the circuit are processed by the same electronics and are reduced tomore » the sensor signals after two demodulation steps. This approach allows a large number of sensors to be interrogated using a single pair of coaxial cables. We successfully developed hardware, firmware, and software to complete a scalable implementation of these microwave control electronics and demonstrated their use in two areas. First, we showed that the electronics can be used at room temperature to read out a network of diverse sensor types relevant to safeguards or process monitoring. Second, we showed that the electronics can be used to measure large numbers of ultrasensitive cryogenic sensors such as gamma-ray microcalorimeters. In particular, we demonstrated the undegraded readout of up to 128 channels and established a path to even higher multiplexing factors. These results have transformed the prospects for gamma-ray spectrometers based on cryogenic microcalorimeter arrays by enabling spectrometers whose collecting areas and count rates can be competitive with high purity germanium but with 10x better spectral resolution.« less

A Simple Sensor Model for THUNDER Actuators

NASA Technical Reports Server (NTRS)

Campbell, Joel F.; Bryant, Robert G.

2009-01-01

A quasi-static (low frequency) model is developed for THUNDER actuators configured as displacement sensors based on a simple Raleigh-Ritz technique. This model is used to calculate charge as a function of displacement. Using this and the calculated capacitance, voltage vs. displacement and voltage vs. electrical load curves are generated and compared with measurements. It is shown this model gives acceptable results and is useful for determining rough estimates of sensor output for various loads, laminate configurations and thicknesses.

Automated Hand-Held UXO Detection, Classification & Discrimination Sensor

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

Bell, Thomas H.

2000-06-12

The research focused on procedures for target discrimination and classification using hand-held EMI sensors. The idea is to have a small, portable sensor that can be operated in a sweep or similar pattern in front of the operator, and that is capable of distinguishing between buried UXO and clutter on the spot. Curing Phase 1, we developed the processing techniques for distinguishing between buried UXO and clutter using the EM61-HH hand-held metal detector.

Sensor Network Middleware for Cyber-Physical Systems: Opportunities and Challenges

NASA Astrophysics Data System (ADS)

Singh, G.

2015-12-01

Wireless Sensor Network middleware typically provides abstractions for common tasks such as atomicity, synchronization and communication with the intention of isolating the developers of distributed applications from lower-level details of the underlying platforms. Developing middleware to meet the performance constraints of applications is an important challenge. Although one would like to develop generic middleware services which can be used in a variety of different applications, efficiency considerations often force developers to design middleware and algorithms customized to specific operational contexts. This presentation will discuss techniques to design middleware that is customizable to suit the performance needs of specific applications. We also discuss the challenges poised in designing middleware for pervasive sensor networks and cyber-physical systems with specific focus on environmental monitoring.

Rapid Multi-Damage Identification for Health Monitoring of Laminated Composites Using Piezoelectric Wafer Sensor Arrays

PubMed Central

Si, Liang; Wang, Qian

2016-01-01

Through the use of the wave reflection from any damage in a structure, a Hilbert spectral analysis-based rapid multi-damage identification (HSA-RMDI) technique with piezoelectric wafer sensor arrays (PWSA) is developed to monitor and identify the presence, location and severity of damage in carbon fiber composite structures. The capability of the rapid multi-damage identification technique to extract and estimate hidden significant information from the collected data and to provide a high-resolution energy-time spectrum can be employed to successfully interpret the Lamb waves interactions with single/multiple damage. Nevertheless, to accomplish the precise positioning and effective quantification of multiple damage in a composite structure, two functional metrics from the RMDI technique are proposed and used in damage identification, which are the energy density metric and the energy time-phase shift metric. In the designed damage experimental tests, invisible damage to the naked eyes, especially delaminations, were detected in the leftward propagating waves as well as in the selected sensor responses, where the time-phase shift spectra could locate the multiple damage whereas the energy density spectra were used to quantify the multiple damage. The increasing damage was shown to follow a linear trend calculated by the RMDI technique. All damage cases considered showed completely the developed RMDI technique potential as an effective online damage inspection and assessment tool. PMID:27153070

Time-Of-Flight Camera, Optical Tracker and Computed Tomography in Pairwise Data Registration

PubMed Central

Badura, Pawel; Juszczyk, Jan; Pietka, Ewa

2016-01-01

Purpose A growing number of medical applications, including minimal invasive surgery, depends on multi-modal or multi-sensors data processing. Fast and accurate 3D scene analysis, comprising data registration, seems to be crucial for the development of computer aided diagnosis and therapy. The advancement of surface tracking system based on optical trackers already plays an important role in surgical procedures planning. However, new modalities, like the time-of-flight (ToF) sensors, widely explored in non-medical fields are powerful and have the potential to become a part of computer aided surgery set-up. Connection of different acquisition systems promises to provide a valuable support for operating room procedures. Therefore, the detailed analysis of the accuracy of such multi-sensors positioning systems is needed. Methods We present the system combining pre-operative CT series with intra-operative ToF-sensor and optical tracker point clouds. The methodology contains: optical sensor set-up and the ToF-camera calibration procedures, data pre-processing algorithms, and registration technique. The data pre-processing yields a surface, in case of CT, and point clouds for ToF-sensor and marker-driven optical tracker representation of an object of interest. An applied registration technique is based on Iterative Closest Point algorithm. Results The experiments validate the registration of each pair of modalities/sensors involving phantoms of four various human organs in terms of Hausdorff distance and mean absolute distance metrics. The best surface alignment was obtained for CT and optical tracker combination, whereas the worst for experiments involving ToF-camera. Conclusion The obtained accuracies encourage to further develop the multi-sensors systems. The presented substantive discussion concerning the system limitations and possible improvements mainly related to the depth information produced by the ToF-sensor is useful for computer aided surgery developers. PMID:27434396

Comments to: A Novel Low-Cost Instrumentation System for Measuring the Water Content and Apparent Electrical Conductivity of Soils, Sensors, 15, 25546⁻25563.

PubMed

Chavanne, Xavier; Bruère, Alain; Frangi, Jean-Pierre

2018-05-28

The article comments on claims made by Rêgo et al. about the sensor they developed to determine soil water content and its salinity via the admittance measurement of electrodes embedded in the soil. Their sensor is not based on a self-balanced bridge, as stated, but on a more common technique relying on Ohm's law. A bridge is a zero method of measurement which can provide direct voltages proportional to soil permittivity and conductivity with a high resolution. Thanks to modern electronics the method can be adapted for fast and continuous monitoring in a remote site. Because of this confusion about the different measurement techniques among available admittance or capacitance sensors, we give a succinct review of them and indicate how they compare to the two techniques under discussion. We also question the ability of Rêgo et al.'s current sensor to determine both soil water content and salinity due first to instrument biases and then to the soil complexity as a dielectric medium. In particular, the choice of sensor frequencies is crucial in the two steps. In addition, the procedure to determine and account for temperature influences on readings is not presented clearly enough. It is important to distinguish between the effect resulting from electronics sensitivity, and those that are soil-specific. The comment does not invalidate the design of the sensor, but indicates points, especially parasitic contributions, which must be dealt with to avoid major errors.

Review of Recent Inkjet-Printed Capacitive Tactile Sensors

PubMed Central

Salim, Ahmed

2017-01-01

Inkjet printing is an advanced printing technology that has been used to develop conducting layers, interconnects and other features on a variety of substrates. It is an additive manufacturing process that offers cost-effective, lightweight designs and simplifies the fabrication process with little effort. There is hardly sufficient research on tactile sensors and inkjet printing. Advancements in materials science and inkjet printing greatly facilitate the realization of sophisticated tactile sensors. Starting from the concept of capacitive sensing, a brief comparison of printing techniques, the essential requirements of inkjet-printing and the attractive features of state-of-the art inkjet-printed tactile sensors developed on diverse substrates (paper, polymer, glass and textile) are presented in this comprehensive review. Recent trends in inkjet-printed wearable/flexible and foldable tactile sensors are evaluated, paving the way for future research. PMID:29125584

Environmental urban runoff monitoring

NASA Astrophysics Data System (ADS)

Yu, Byunggu; Behera, Pradeep K.; Kim, Seon Ho; Ramirez Rochac, Juan F.; Branham, Travis

2010-04-01

Urban stormwater runoff has been a critical and chronic problem in the quantity and quality of receiving waters, resulting in a major environmental concern. To address this problem engineers and professionals have developed a number of solutions which include various monitoring and modeling techniques. The most fundamental issue in these solutions is accurate monitoring of the quantity and quality of the runoff from both combined and separated sewer systems. This study proposes a new water quantity monitoring system, based on recent developments in sensor technology. Rather than using a single independent sensor, we harness an intelligent sensor platform that integrates various sensors, a wireless communication module, data storage, a battery, and processing power such that more comprehensive, efficient, and scalable data acquisition becomes possible. Our experimental results show the feasibility and applicability of such a sensor platform in the laboratory test setting.

Coal thickness guage using RRAS techniques, parts 2 and 3

NASA Technical Reports Server (NTRS)

King, J. D.; Rollwitz, W. L.

1980-01-01

Electron magnetic resonance was investigated as a sensing technique for use in measuring the thickness of the layer of coal overlying the rock substrate. The goal is development of a thickness gauge which will be usable for control of mining machinery to maintain the coal thickness within selected bounds. A sensor must be noncontracting, have a measurement range of 6 inches or more, and an accuracy of 1/2 inch or better. The sensor should be insensitive to variations in spacing between the sensor and the surface, the response speed should be adequate to permit use on continuous mining equipment, and the device should be rugged and otherwise suited for operation under conditions of high vibration, moisture, and dust. Finally, the sensor measurement must not be adversely affected by the natural effects occurring in coal such as impurities, voids, cracks, layering, high moisture level, and other conditions that are likely to be encountered.

Development of a Hydrogen Peroxide Sensor Based on Screen-Printed Electrodes Modified with Inkjet-Printed Prussian Blue Nanoparticles

PubMed Central

Cinti, Stefano; Arduini, Fabiana; Moscone, Danila; Palleschi, Giuseppe; Killard, Anthony J.

2014-01-01

A sensor for the simple and sensitive measurement of hydrogen peroxide has been developed which is based on screen printed electrodes (SPEs) modified with Prussian blue nanoparticles (PBNPs) deposited using piezoelectric inkjet printing. PBNP-modified SPEs were characterized using physical and electrochemical techniques to optimize the PBNP layer thickness and electroanalytical conditions for optimum measurement of hydrogen peroxide. Sensor optimization resulted in a limit of detection of 2 × 10−7 M, a linear range from 0 to 4.5 mM and a sensitivity of 762 μA·mM−1·cm−2 which was achieved using 20 layers of printed PBNPs. Sensors also demonstrated excellent reproducibility (<5% rsd). PMID:25093348

Compressive Sensing Image Sensors-Hardware Implementation

PubMed Central

Dadkhah, Mohammadreza; Deen, M. Jamal; Shirani, Shahram

2013-01-01

The compressive sensing (CS) paradigm uses simultaneous sensing and compression to provide an efficient image acquisition technique. The main advantages of the CS method include high resolution imaging using low resolution sensor arrays and faster image acquisition. Since the imaging philosophy in CS imagers is different from conventional imaging systems, new physical structures have been developed for cameras that use the CS technique. In this paper, a review of different hardware implementations of CS encoding in optical and electrical domains is presented. Considering the recent advances in CMOS (complementary metal–oxide–semiconductor) technologies and the feasibility of performing on-chip signal processing, important practical issues in the implementation of CS in CMOS sensors are emphasized. In addition, the CS coding for video capture is discussed. PMID:23584123

Autonomous space target recognition and tracking approach using star sensors based on a Kalman filter.

PubMed

Ye, Tao; Zhou, Fuqiang

2015-04-10

When imaged by detectors, space targets (including satellites and debris) and background stars have similar point-spread functions, and both objects appear to change as detectors track targets. Therefore, traditional tracking methods cannot separate targets from stars and cannot directly recognize targets in 2D images. Consequently, we propose an autonomous space target recognition and tracking approach using a star sensor technique and a Kalman filter (KF). A two-step method for subpixel-scale detection of star objects (including stars and targets) is developed, and the combination of the star sensor technique and a KF is used to track targets. The experimental results show that the proposed method is adequate for autonomously recognizing and tracking space targets.

Satellite stratospheric aerosol measurement validation

NASA Technical Reports Server (NTRS)

Russell, P. B.; Mccormick, M. P.

1984-01-01

The validity of the stratospheric aerosol measurements made by the satellite sensors SAM II and SAGE was tested by comparing their results with each other and with results obtained by other techniques (lider, dustsonde, filter, and impactor). The latter type of comparison required the development of special techniques that convert the quantity measured by the correlative sensor (e.g. particle backscatter, number, or mass) to that measured by the satellite sensor (extinction) and quantitatively estimate the uncertainty in the conversion process. The results of both types of comparisons show agreement within the measurement and conversion uncertainties. Moreover, the satellite uncertainty is small compared to aerosol natural variability (caused by seasonal changes, volcanoes, sudden warmings, and vortex structure). It was concluded that the satellite measurements are valid.

A comparison of force sensing techniques for planetary manipulation

NASA Technical Reports Server (NTRS)

Helmick, Daniel; Okon, Avi; DiCicco, Matt

2006-01-01

Five techniques for sensing forces with a manipulator are compared analytically and experimentally. The techniques compared are: a six-axis wrist force/torque sensor, joint torque sensors, link strain gauges, motor current sensors, and flexibility modeling. The accuracy and repeatability fo each technique is quantified and compared.

An air flow sensor for neonatal mechanical ventilation applications based on a novel fiber-optic sensing technique.

PubMed

Battista, L; Sciuto, S A; Scorza, A

2013-03-01

In this work, a simple and low-cost air flow sensor, based on a novel fiber-optic sensing technique has been developed for monitoring air flows rates supplied by a neonatal ventilator to support infants in intensive care units. The device is based on a fiber optic sensing technique allowing (a) the immunity to light intensity variations independent by measurand and (b) the reduction of typical shortcomings affecting all biomedical fields (electromagnetic interference and patient electrical safety). The sensing principle is based on the measurement of transversal displacement of an emitting fiber-optic cantilever due to action of air flow acting on it; the fiber tip displacement is measured by means of a photodiode linear array, placed in front of the entrance face of the emitting optical fiber in order to detect its light intensity profile. As the measurement system is based on a detection of the illumination pattern, and not on an intensity modulation technique, it results less sensitive to light intensity fluctuation independent by measurand than intensity-based sensors. The considered technique is here adopted in order to develop two different configurations for an air flow sensor suitable for the measurement of air flow rates typically occurring during mechanical ventilation of newborns: a mono-directional and a bi-directional transducer have been proposed. A mathematical model for the air flow sensor is here proposed and a static calibration of two different arrangements has been performed: a measurement range up to 3.00 × 10(-4) m(3)∕s (18.0 l∕min) for the mono-directional sensor and a measurement range of ±3.00 × 10(-4) m(3)∕s (±18.0 l∕min) for the bi-directional sensor are experimentally evaluated, according to the air flow rates normally encountered during tidal breathing of infants with a mass lower than 10 kg. Experimental data of static calibration result in accordance with the proposed theoretical model: for the mono-directional configuration, the coefficient of determination r(2) is equal to 0.997; for the bi-directional configuration, the coefficient of determination r(2) is equal to 0.990 for positive flows (inspiration) and 0.988 for negative flows (expiration). Measurement uncertainty δQ of air flow rate has been evaluated by means of the propagation of distributions and the percentage error in the arrangement of bi-directional sensor ranges from a minimum of about 0.5% at -18.0 l∕min to a maximum of about 9% at -12.0 l∕min.

An air flow sensor for neonatal mechanical ventilation applications based on a novel fiber-optic sensing technique

NASA Astrophysics Data System (ADS)

Battista, L.; Sciuto, S. A.; Scorza, A.

2013-03-01

In this work, a simple and low-cost air flow sensor, based on a novel fiber-optic sensing technique has been developed for monitoring air flows rates supplied by a neonatal ventilator to support infants in intensive care units. The device is based on a fiber optic sensing technique allowing (a) the immunity to light intensity variations independent by measurand and (b) the reduction of typical shortcomings affecting all biomedical fields (electromagnetic interference and patient electrical safety). The sensing principle is based on the measurement of transversal displacement of an emitting fiber-optic cantilever due to action of air flow acting on it; the fiber tip displacement is measured by means of a photodiode linear array, placed in front of the entrance face of the emitting optical fiber in order to detect its light intensity profile. As the measurement system is based on a detection of the illumination pattern, and not on an intensity modulation technique, it results less sensitive to light intensity fluctuation independent by measurand than intensity-based sensors. The considered technique is here adopted in order to develop two different configurations for an air flow sensor suitable for the measurement of air flow rates typically occurring during mechanical ventilation of newborns: a mono-directional and a bi-directional transducer have been proposed. A mathematical model for the air flow sensor is here proposed and a static calibration of two different arrangements has been performed: a measurement range up to 3.00 × 10-4 m3/s (18.0 l/min) for the mono-directional sensor and a measurement range of ±3.00 × 10-4 m3/s (±18.0 l/min) for the bi-directional sensor are experimentally evaluated, according to the air flow rates normally encountered during tidal breathing of infants with a mass lower than 10 kg. Experimental data of static calibration result in accordance with the proposed theoretical model: for the mono-directional configuration, the coefficient of determination r2 is equal to 0.997; for the bi-directional configuration, the coefficient of determination r2 is equal to 0.990 for positive flows (inspiration) and 0.988 for negative flows (expiration). Measurement uncertainty δQ of air flow rate has been evaluated by means of the propagation of distributions and the percentage error in the arrangement of bi-directional sensor ranges from a minimum of about 0.5% at -18.0 l/min to a maximum of about 9% at -12.0 l/min.

Intelligent structural health monitoring of vehicular bridges using fiber optic sensors to detect acoustic emission.

DOT National Transportation Integrated Search

2011-01-28

The recent collapse of the I-35W Mississippi River Bridge in Minneapolis has spawned a growing : interest in the development of reliable techniques for evaluating the structural integrity of civil : infrastructure. Current inspection techniques tailo...

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

NASA Technical Reports Server (NTRS)

Piazza, Anthony

2008-01-01

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

EDITORIAL: Sensors and sensing systems

NASA Astrophysics Data System (ADS)

Dewhurst, Richard; Tian, Gui Yun

2008-02-01

Sensors are very important for measurement science and technology. They serve as a vital component in new measurement techniques and instrumentation systems. Key qualities of a good sensor system are high resolution, high reliability, low cost, appropriate output for a given input (good sensitivity), rapid response time, small random error in results, and small systematic error. Linearity is also useful, but with the advent of lookup tables and software, it is not as important as it used to be. In the last several years, considerable effort around the world has been devoted to a wide range of sensors from nanoscale sensors to sensor networks. Collectively, these vast and multidisciplinary efforts are developing important technological roadmaps to futuristic sensors with new modalities, significantly enhanced effectiveness and integrated functionality (data processing, computation, decision making and communications). When properly organized, they will have important relevance to life science and security applications, e.g. the sensing and monitoring of chemical, biological, radiological and explosive threats. A special feature in this issue takes a snapshot of some recent developments that were first presented at an international conference, the 2007 IEEE International Conference on Networking, Sensing and Control (ICNSC). The conference discussed recent developments, from which a few papers have since been brought together in this special feature. Gas sensing for environmental monitoring remains a topical subject, and two papers deal with this issue. One is concerned with the exploitation of nanostructured Au-doped cobalt oxyhydroxide-based carbon monoxide sensors for fire detection at its earlier stages (Zhuiykov and Dowling), whilst another examines the role of oxygen in high temperature hydrogen sulfide detection using MISiC sensors (Weng et al). Again for environmental monitoring, another paper deals with accurate sound source localization in a reverberant environment using multiple acoustic sensors (Atmoko et al). Not only is gaseous monitoring important, there are particular difficulties when it comes to the continuous monitoring of solids by non-destructive evaluation techniques. Examples of potential solutions for specialist applications are sensors for the detection and measurement of thin dielectric layers using reflection of frequency-scanned millimetre electromagnetic waves (Bowring et al), and an electrostatic sensor for velocity measurements of pneumatically conveyed solid particles (Xu et al). For potential medical applications, position measurement of internal organs is an on-going challenge. Tracking of internal organ motion with a six degree-of-freedom MEMS sensor is discussed by Bandala and Joyce. We hope that these papers provide an insight into exciting developments that continue to take place in the field of sensors and control.

Proposed evaluation framework for assessing operator performance with multisensor displays

NASA Technical Reports Server (NTRS)

Foyle, David C.

1992-01-01

Despite aggressive work on the development of sensor fusion algorithms and techniques, no formal evaluation procedures have been proposed. Based on existing integration models in the literature, an evaluation framework is developed to assess an operator's ability to use multisensor, or sensor fusion, displays. The proposed evaluation framework for evaluating the operator's ability to use such systems is a normative approach: The operator's performance with the sensor fusion display can be compared to the models' predictions based on the operator's performance when viewing the original sensor displays prior to fusion. This allows for the determination as to when a sensor fusion system leads to: 1) poorer performance than one of the original sensor displays (clearly an undesirable system in which the fused sensor system causes some distortion or interference); 2) better performance than with either single sensor system alone, but at a sub-optimal (compared to the model predictions) level; 3) optimal performance (compared to model predictions); or, 4) super-optimal performance, which may occur if the operator were able to use some highly diagnostic 'emergent features' in the sensor fusion display, which were unavailable in the original sensor displays. An experiment demonstrating the usefulness of the proposed evaluation framework is discussed.

New radiological material detection technologies for nuclear forensics: Remote optical imaging and graphene-based sensors.

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

Harrison, Richard Karl; Martin, Jeffrey B.; Wiemann, Dora K.

We developed new detector technologies to identify the presence of radioactive materials for nuclear forensics applications. First, we investigated an optical radiation detection technique based on imaging nitrogen fluorescence excited by ionizing radiation. We demonstrated optical detection in air under indoor and outdoor conditions for alpha particles and gamma radiation at distances up to 75 meters. We also contributed to the development of next generation systems and concepts that could enable remote detection at distances greater than 1 km, and originated a concept that could enable daytime operation of the technique. A second area of research was the development ofmore » room-temperature graphene-based sensors for radiation detection and measurement. In this project, we observed tunable optical and charged particle detection, and developed improved devices. With further development, the advancements described in this report could enable new capabilities for nuclear forensics applications.« less

Detection of Carbon Monoxide Using Polymer-Carbon Composite Films

NASA Technical Reports Server (NTRS)

Homer, Margie L.; Ryan, Margaret A.; Lara, Liana M.

2011-01-01

A carbon monoxide (CO) sensor was developed that can be incorporated into an existing sensing array architecture. The CO sensor is a low-power chemiresistor that operates at room temperature, and the sensor fabrication techniques are compatible with ceramic substrates. Sensors made from four different polymers were tested: poly (4-vinylpryridine), ethylene-propylene-diene-terpolymer, polyepichlorohydrin, and polyethylene oxide (PEO). The carbon black used for the composite films was Black Pearls 2000, a furnace black made by the Cabot Corporation. Polymers and carbon black were used as received. In fact, only two of these sensors showed a good response to CO. The poly (4-vinylpryridine) sensor is noisy, but it does respond to the CO above 200 ppm. The polyepichlorohydrin sensor is less noisy and shows good response down to 100 ppm.

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

PubMed

Pospíšilová, Marie; Kuncová, Gabriela; Trögl, Josef

2015-09-30

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

Polyacrylonitrile nanofiber as polar solvent N,N-dimethyl formamide sensor based on quartz crystal microbalance technique

NASA Astrophysics Data System (ADS)

Rianjanu, A.; Julian, T.; Hidayat, S. N.; Suyono, E. A.; Kusumaatmaja, A.; Triyana, K.

2018-04-01

Here, we describe an N,N-dimethyl formamide (DMF) vapour sensor fabricated by coating polyacrylonitrile (PAN) nanofiber structured on quartz crystal microbalance (QCM). The PAN nanofiber sensors with an average diameter of 225 nm to 310 nm were fabricated via electrospinning process with different mass deposition on QCM substrate. The nanostructured of PAN nanofiber offers a high specific surface area that improved the sensing performance of nanofiber sensors. Benefiting from that fine structure, and high polymer-solvent affinity between PAN and DMF, the development of DMF sensors presented good response at ambient temperature. Since there is no chemical reaction between PAN nanofiber and DMF vapour, weak physical interaction such absorption and swelling were responsible for the sensing behavior. The results are indicating that the response of PAN nanofiber sensors has more dependency on the nanofiber structure (specific surface area) rather than its mass deposition. The sensor also showed good stability after a few days sensing. These findings have significant implications for developing DMF vapour sensor based on QCM coated polymer nanofibers.

Comparison of Calibration Techniques for Low-Cost Air Quality Monitoring

NASA Astrophysics Data System (ADS)

Malings, C.; Ramachandran, S.; Tanzer, R.; Kumar, S. P. N.; Hauryliuk, A.; Zimmerman, N.; Presto, A. A.

2017-12-01

Assessing the intra-city spatial distribution and temporal variability of air quality can be facilitated by a dense network of monitoring stations. However, the cost of implementing such a network can be prohibitive if high-quality but high-cost monitoring systems are used. To this end, the Real-time Affordable Multi-Pollutant (RAMP) sensor package has been developed at the Center for Atmospheric Particle Studies of Carnegie Mellon University, in collaboration with SenSevere LLC. This self-contained unit can measure up to five gases out of CO, SO2, NO, NO2, O3, VOCs, and CO2, along with temperature and relative humidity. Responses of individual gas sensors can vary greatly even when exposed to the same ambient conditions. Those of VOC sensors in particular were observed to vary by a factor-of-8, which suggests that each sensor requires its own calibration model. To this end, we apply and compare two different calibration methods to data collected by RAMP sensors collocated with a reference monitor station. The first method, random forest (RF) modeling, is a rule-based method which maps sensor responses to pollutant concentrations by implementing a trained sequence of decision rules. RF modeling has previously been used for other RAMP gas sensors by the group, and has produced precise calibrated measurements. However, RF models can only predict pollutant concentrations within the range observed in the training data collected during the collocation period. The second method, Gaussian process (GP) modeling, is a probabilistic Bayesian technique whereby broad prior estimates of pollutant concentrations are updated using sensor responses to generate more refined posterior predictions, as well as allowing predictions beyond the range of the training data. The accuracy and precision of these techniques are assessed and compared on VOC data collected during the summer of 2017 in Pittsburgh, PA. By combining pollutant data gathered by each RAMP sensor and applying appropriate calibration techniques, the potentially noisy or biased responses of individual sensors can be mapped to pollutant concentration values which are comparable to those of reference instruments.

Absolute Radiometric Calibration of Narrow-Swath Imaging Sensors with Reference to Non-Coincident Wide-Swath Sensors

NASA Technical Reports Server (NTRS)

McCorkel, Joel; Thome, Kurtis; Lockwood, Ronald

2012-01-01

An inter-calibration method is developed to provide absolute radiometric calibration of narrow-swath imaging sensors with reference to non-coincident wide-swath sensors. The method predicts at-sensor radiance using non-coincident imagery from the reference sensor and knowledge of spectral reflectance of the test site. The imagery of the reference sensor is restricted to acquisitions that provide similar view and solar illumination geometry to reduce uncertainties due to directional reflectance effects. Spectral reflectance of the test site is found with a simple iterative radiative transfer method using radiance values of a well-understood wide-swath sensor and spectral shape information based on historical ground-based measurements. At-sensor radiance is calculated for the narrow-swath sensor using this spectral reflectance and atmospheric parameters that are also based on historical in situ measurements. Results of the inter-calibration method show agreement on the 2 5 percent level in most spectral regions with the vicarious calibration technique relying on coincident ground-based measurements referred to as the reflectance-based approach. While the variability of the inter-calibration method based on non-coincident image pairs is significantly larger, results are consistent with techniques relying on in situ measurements. The method is also insensitive to spectral differences between the sensors by transferring to surface spectral reflectance prior to prediction of at-sensor radiance. The utility of this inter-calibration method is made clear by its flexibility to utilize image pairings with acquisition dates differing in excess of 30 days allowing frequent absolute calibration comparisons between wide- and narrow-swath sensors.

A Field Programmable Gate Array-Based Reconfigurable Smart-Sensor Network for Wireless Monitoring of New Generation Computer Numerically Controlled Machines

PubMed Central

Moreno-Tapia, Sandra Veronica; Vera-Salas, Luis Alberto; Osornio-Rios, Roque Alfredo; Dominguez-Gonzalez, Aurelio; Stiharu, Ion; de Jesus Romero-Troncoso, Rene

2010-01-01

Computer numerically controlled (CNC) machines have evolved to adapt to increasing technological and industrial requirements. To cover these needs, new generation machines have to perform monitoring strategies by incorporating multiple sensors. Since in most of applications the online Processing of the variables is essential, the use of smart sensors is necessary. The contribution of this work is the development of a wireless network platform of reconfigurable smart sensors for CNC machine applications complying with the measurement requirements of new generation CNC machines. Four different smart sensors are put under test in the network and their corresponding signal processing techniques are implemented in a Field Programmable Gate Array (FPGA)-based sensor node. PMID:22163602

A field programmable gate array-based reconfigurable smart-sensor network for wireless monitoring of new generation computer numerically controlled machines.

PubMed

Moreno-Tapia, Sandra Veronica; Vera-Salas, Luis Alberto; Osornio-Rios, Roque Alfredo; Dominguez-Gonzalez, Aurelio; Stiharu, Ion; Romero-Troncoso, Rene de Jesus

2010-01-01

Computer numerically controlled (CNC) machines have evolved to adapt to increasing technological and industrial requirements. To cover these needs, new generation machines have to perform monitoring strategies by incorporating multiple sensors. Since in most of applications the online Processing of the variables is essential, the use of smart sensors is necessary. The contribution of this work is the development of a wireless network platform of reconfigurable smart sensors for CNC machine applications complying with the measurement requirements of new generation CNC machines. Four different smart sensors are put under test in the network and their corresponding signal processing techniques are implemented in a Field Programmable Gate Array (FPGA)-based sensor node.

Sensors Based on Bio and Biomimetic Receptors in Medical Diagnostic, Environment, and Food Analysis.

PubMed

Kozitsina, Alisa N; Svalova, Tatiana S; Malysheva, Natalia N; Okhokhonin, Andrei V; Vidrevich, Marina B; Brainina, Khiena Z

2018-04-01

Analytical chemistry is now developing mainly in two areas: automation and the creation of complexes that allow, on the one hand, for simultaneously analyzing a large number of samples without the participation of an operator, and on the other, the development of portable miniature devices for personalized medicine and the monitoring of a human habitat. The sensor devices, the great majority of which are biosensors and chemical sensors, perform the role of the latter. That last line is considered in the proposed review. Attention is paid to transducers, receptors, techniques of immobilization of the receptor layer on the transducer surface, processes of signal generation and detection, and methods for increasing sensitivity and accuracy. The features of sensors based on synthetic receptors and additional components (aptamers, molecular imprinted polymers, biomimetics) are discussed. Examples of bio- and chemical sensors' application are given. Miniaturization paths, new power supply means, and wearable and printed sensors are described. Progress in this area opens a revolutionary era in the development of methods of on-site and in-situ monitoring, that is, paving the way from the "test-tube to the smartphone".

ROBUST ONLINE MONITORING FOR CALIBRATION ASSESSMENT OF TRANSMITTERS AND INSTRUMENTATION

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

Ramuhalli, Pradeep; Tipireddy, Ramakrishna; Lerchen, Megan E.

Robust online monitoring (OLM) technologies are expected to enable the extension or elimination of periodic sensor calibration intervals in operating and new reactors. Specifically, the next generation of OLM technology is expected to include newly developed advanced algorithms that improve monitoring of sensor/system performance and enable the use of plant data to derive information that currently cannot be measured. These advances in OLM technologies will improve the safety and reliability of current and planned nuclear power systems through improved accuracy and increased reliability of sensors used to monitor key parameters. In this paper, we discuss an overview of research beingmore » performed within the Nuclear Energy Enabling Technologies (NEET)/Advanced Sensors and Instrumentation (ASI) program, for the development of OLM algorithms to use sensor outputs and, in combination with other available information, 1) determine whether one or more sensors are out of calibration or failing and 2) replace a failing sensor with reliable, accurate sensor outputs. Algorithm development is focused on the following OLM functions: • Signal validation – fault detection and selection of acceptance criteria • Virtual sensing – signal value prediction and acceptance criteria • Response-time assessment – fault detection and acceptance criteria selection A GP-based uncertainty quantification (UQ) method previously developed for UQ in OLM, was adapted for use in sensor-fault detection and virtual sensing. For signal validation, the various components to the OLM residual (which is computed using an AAKR model) were explicitly defined and modeled using a GP. Evaluation was conducted using flow loop data from multiple sources. Results using experimental data from laboratory-scale flow loops indicate that the approach, while capable of detecting sensor drift, may be incapable of discriminating between sensor drift and model inadequacy. This may be due to a simplification applied in the initial modeling, where the sensor degradation is assumed to be stationary. In the case of virtual sensors, the GP model was used in a predictive mode to estimate the correct sensor reading for sensors that may have failed. Results have indicated the viability of using this approach for virtual sensing. However, the GP model has proven to be computationally expensive, and so alternative algorithms for virtual sensing are being evaluated. Finally, automated approaches to performing noise analysis for extracting sensor response time were developed. Evaluation of this technique using laboratory-scale data indicates that it compares well with manual techniques previously used for noise analysis. Moreover, the automated and manual approaches for noise analysis also compare well with the current “gold standard”, hydraulic ramp testing, for response time monitoring. Ongoing research in this project is focused on further evaluation of the algorithms, optimization for accuracy and computational efficiency, and integration into a suite of tools for robust OLM that are applicable to monitoring sensor calibration state in nuclear power plants.« less

A real-time spectroscopic sensor for monitoring laser welding processes.

PubMed

Sibillano, Teresa; Ancona, Antonio; Berardi, Vincenzo; Lugarà, Pietro Mario

2009-01-01

In this paper we report on the development of a sensor for real time monitoring of laser welding processes based on spectroscopic techniques. The system is based on the acquisition of the optical spectra emitted from the laser generated plasma plume and their use to implement an on-line algorithm for both the calculation of the plasma electron temperature and the analysis of the correlations between selected spectral lines. The sensor has been patented and it is currently available on the market.

The application of smart sensor techniques to a solid-state array multispectral sensor

NASA Technical Reports Server (NTRS)

Mcfadin, L. W.

1978-01-01

The solid-state array spectroradiometer (SAS) developed at JSC for remote sensing applications is a multispectral sensor which has no moving parts, is virtually maintenance-free, and has the ability to provide data which requires a minimum of processing. The instrument is based on the 42 x 342 element charge injection device (CID) detector. This system allows the combination of spectral scanning and across-track spatial scanning along with its associated digitization electronics into a single detector.

Self-Tuning Method for Increased Obstacle Detection Reliability Based on Internet of Things LiDAR Sensor Models

PubMed Central

2018-01-01

On-chip LiDAR sensors for vehicle collision avoidance are a rapidly expanding area of research and development. The assessment of reliable obstacle detection using data collected by LiDAR sensors has become a key issue that the scientific community is actively exploring. The design of a self-tuning methodology and its implementation are presented in this paper, to maximize the reliability of LiDAR sensors network for obstacle detection in the ‘Internet of Things’ (IoT) mobility scenarios. The Webots Automobile 3D simulation tool for emulating sensor interaction in complex driving environments is selected in order to achieve that objective. Furthermore, a model-based framework is defined that employs a point-cloud clustering technique, and an error-based prediction model library that is composed of a multilayer perceptron neural network, and k-nearest neighbors and linear regression models. Finally, a reinforcement learning technique, specifically a Q-learning method, is implemented to determine the number of LiDAR sensors that are required to increase sensor reliability for obstacle localization tasks. In addition, a IoT driving assistance user scenario, connecting a five LiDAR sensor network is designed and implemented to validate the accuracy of the computational intelligence-based framework. The results demonstrated that the self-tuning method is an appropriate strategy to increase the reliability of the sensor network while minimizing detection thresholds. PMID:29748521

Self-Tuning Method for Increased Obstacle Detection Reliability Based on Internet of Things LiDAR Sensor Models.

PubMed

Castaño, Fernando; Beruvides, Gerardo; Villalonga, Alberto; Haber, Rodolfo E

2018-05-10

On-chip LiDAR sensors for vehicle collision avoidance are a rapidly expanding area of research and development. The assessment of reliable obstacle detection using data collected by LiDAR sensors has become a key issue that the scientific community is actively exploring. The design of a self-tuning methodology and its implementation are presented in this paper, to maximize the reliability of LiDAR sensors network for obstacle detection in the 'Internet of Things' (IoT) mobility scenarios. The Webots Automobile 3D simulation tool for emulating sensor interaction in complex driving environments is selected in order to achieve that objective. Furthermore, a model-based framework is defined that employs a point-cloud clustering technique, and an error-based prediction model library that is composed of a multilayer perceptron neural network, and k-nearest neighbors and linear regression models. Finally, a reinforcement learning technique, specifically a Q-learning method, is implemented to determine the number of LiDAR sensors that are required to increase sensor reliability for obstacle localization tasks. In addition, a IoT driving assistance user scenario, connecting a five LiDAR sensor network is designed and implemented to validate the accuracy of the computational intelligence-based framework. The results demonstrated that the self-tuning method is an appropriate strategy to increase the reliability of the sensor network while minimizing detection thresholds.

A novel radar sensor for the non-contact detection of speech signals.

PubMed

Jiao, Mingke; Lu, Guohua; Jing, Xijing; Li, Sheng; Li, Yanfeng; Wang, Jianqi

2010-01-01

Different speech detection sensors have been developed over the years but they are limited by the loss of high frequency speech energy, and have restricted non-contact detection due to the lack of penetrability. This paper proposes a novel millimeter microwave radar sensor to detect speech signals. The utilization of a high operating frequency and a superheterodyne receiver contributes to the high sensitivity of the radar sensor for small sound vibrations. In addition, the penetrability of microwaves allows the novel sensor to detect speech signals through nonmetal barriers. Results show that the novel sensor can detect high frequency speech energies and that the speech quality is comparable to traditional microphone speech. Moreover, the novel sensor can detect speech signals through a nonmetal material of a certain thickness between the sensor and the subject. Thus, the novel speech sensor expands traditional speech detection techniques and provides an exciting alternative for broader application prospects.

A Novel Radar Sensor for the Non-Contact Detection of Speech Signals

PubMed Central

Jiao, Mingke; Lu, Guohua; Jing, Xijing; Li, Sheng; Li, Yanfeng; Wang, Jianqi

2010-01-01

Different speech detection sensors have been developed over the years but they are limited by the loss of high frequency speech energy, and have restricted non-contact detection due to the lack of penetrability. This paper proposes a novel millimeter microwave radar sensor to detect speech signals. The utilization of a high operating frequency and a superheterodyne receiver contributes to the high sensitivity of the radar sensor for small sound vibrations. In addition, the penetrability of microwaves allows the novel sensor to detect speech signals through nonmetal barriers. Results show that the novel sensor can detect high frequency speech energies and that the speech quality is comparable to traditional microphone speech. Moreover, the novel sensor can detect speech signals through a nonmetal material of a certain thickness between the sensor and the subject. Thus, the novel speech sensor expands traditional speech detection techniques and provides an exciting alternative for broader application prospects. PMID:22399895

Basement Membrane-Based Glucose Sensor Coatings Enhance Continuous Glucose Monitoring in Vivo.

PubMed

Klueh, Ulrike; Qiao, Yi; Czajkowski, Caroline; Ludzinska, Izabela; Antar, Omar; Kreutzer, Donald L

2015-08-25

Implantable glucose sensors demonstrate a rapid decline in function that is likely due to biofouling of the sensor. Previous efforts directed at overcoming this issue has generally focused on the use of synthetic polymer coatings, with little apparent effect in vivo, clearly a novel approach is required. We believe that the key to extending sensor life span in vivo is the development of biocompatible basement membrane (BM) based bio-hydrogels as coatings for glucose sensors. BM based bio-hydrogel sensor coatings were developed using purified BM preparations (ie, Cultrex from Trevigen Inc). Modified Abbott sensors were coated with Cultrex BM extracts. Sensor performance was evaluated for the impact of these coatings in vitro and in vivo in a continuous glucose monitoring (CGM) mouse model. In vivo sensor function was assessed over a 28-day time period expressed as mean absolute relative difference (MARD) values. Tissue reactivity of both Cultrex coated and uncoated glucose sensors was evaluated at 7, 14, 21 and 28 days post-sensor implantation with standard histological techniques. The data demonstrate that Cultrex-based sensor coatings had no effect on glucose sensor function in vitro. In vivo glucose sensor performance was enhanced following BM coating as determined by MARD analysis, particularly in weeks 2 and 3. In vivo studies also demonstrated that Cultrex coatings significantly decreased sensor-induced tissue reactions at the sensor implantation sites. Basement-membrane-based sensor coatings enhance glucose sensor function in vivo, by minimizing or preventing sensor-induced tissues reactions. © 2015 Diabetes Technology Society.

Novel EO/IR sensor technologies

NASA Astrophysics Data System (ADS)

Lewis, Keith

2011-10-01

The requirements for advanced EO/IR sensor technologies are discussed in the context of evolving military operations, with significant emphasis on the development of new sensing technologies to meet the challenges posed by asymmetric threats. The Electro-Magnetic Remote Sensing (EMRS DTC) was established in 2003 to provide a centre of excellence in sensor research and development, supporting new capabilities in key military areas such as precision attack, battlespace manoeuvre and information superiority. In the area of advanced electro-optic technology, the DTC has supported work on discriminative imaging, advanced detectors, laser components/technologies, and novel optical techniques. This paper provides a summary of some of the EO/IR technologies explored by the DTC.

A survey of current solid state star tracker technology

NASA Astrophysics Data System (ADS)

Armstrong, R. W.; Staley, D. A.

1985-12-01

This paper is a survey of the current state of the art in design of star trackers for spacecraft attitude determination systems. Specific areas discussed are sensor technology, including the current state-of-the-art solid state sensors and techniques of mounting and cooling the sensor, analog image preprocessing electronics performance, and digital processing hardware and software. Three examples of area array solid state star tracker development are presented - ASTROS, developed by the Jet Propulsion Laboratory, the Retroreflector Field Tracker (RFT) by Ball Aerospace, and TRW's MADAN. Finally, a discussion of solid state line arrays explores the possibilities for one-dimensional imagers which offer simplified scan control electronics.

Development and validation of a sensor-based health monitoring model for the Parkview Bridge deck.

DOT National Transportation Integrated Search

2012-01-31

Accelerated bridge construction (ABC) using full-depth precast deck panels is an innovative technique that brings all : the benefits listed under ABC to full fruition. However, this technique needs to be evaluated and the performance of : the bridge ...

Microwave bale moisture sensing: Field trial

USDA-ARS?s Scientific Manuscript database

A microwave moisture measurement technique was developed for moisture sensing of cotton bales after the bale press. The technique measures the propagation delay of a microwave signal that is transmitted through the cotton bale. This research conducted a field trial to test the sensor in a commercial...

Optimizing Distributed Sensor Placement for Border Patrol Interdiction Using Microsoft Excel

DTIC Science & Technology

2007-04-01

weather conditions and they can be evaded by using techniques which minimize heat signatures use of lasers and other technologies day or night (26:8...technologies which can be used for border security. Maier [2004] developed a seismic intrusion sensor technology which uses fiber optic cables, lasers , and...needed to create the is used as the base map for the network. program originally developed by Keyhole by Google Inc. It provides satellite images of

Real-time particulate mass measurement based on laser scattering

NASA Astrophysics Data System (ADS)

Rentz, Julia H.; Mansur, David; Vaillancourt, Robert; Schundler, Elizabeth; Evans, Thomas

2005-11-01

OPTRA has developed a new approach to the determination of particulate size distribution from a measured, composite, laser angular scatter pattern. Drawing from the field of infrared spectroscopy, OPTRA has employed a multicomponent analysis technique which uniquely recognizes patterns associated with each particle size "bin" over a broad range of sizes. The technique is particularly appropriate for overlapping patterns where large signals are potentially obscuring weak ones. OPTRA has also investigated a method for accurately training the algorithms without the use of representative particles for any given application. This streamlined calibration applies a one-time measured "instrument function" to theoretical Mie patterns to create the training data for the algorithms. OPTRA has demonstrated this algorithmic technique on a compact, rugged, laser scatter sensor head we developed for gas turbine engine emissions measurements. The sensor contains a miniature violet solid state laser and an array of silicon photodiodes, both of which are commercial off the shelf. The algorithmic technique can also be used with any commercially available laser scatter system.

Recent developments of genetically encoded optical sensors for cell biology.

PubMed

Bolbat, Andrey; Schultz, Carsten

2017-01-01

Optical sensors are powerful tools for live cell research as they permit to follow the location, concentration changes or activities of key cellular players such as lipids, ions and enzymes. Most of the current sensor probes are based on fluorescence which provides great spatial and temporal precision provided that high-end microscopy is used and that the timescale of the event of interest fits the response time of the sensor. Many of the sensors developed in the past 20 years are genetically encoded. There is a diversity of designs leading to simple or sometimes complicated applications for the use in live cells. Genetically encoded sensors began to emerge after the discovery of fluorescent proteins, engineering of their improved optical properties and the manipulation of their structure through application of circular permutation. In this review, we will describe a variety of genetically encoded biosensor concepts, including those for intensiometric and ratiometric sensors based on single fluorescent proteins, Forster resonance energy transfer-based sensors, sensors utilising bioluminescence, sensors using self-labelling SNAP- and CLIP-tags, and finally tetracysteine-based sensors. We focus on the newer developments and discuss the current approaches and techniques for design and application. This will demonstrate the power of using optical sensors in cell biology and will help opening the field to more systematic applications in the future. © 2016 Société Française des Microscopies and Société de Biologie Cellulaire de France. Published by John Wiley & Sons Ltd.

Characterization of Dispersive Ultrasonic Rayleigh Surface Waves in Asphalt Concrete

NASA Astrophysics Data System (ADS)

In, Chi-Won; Kim, Jin-Yeon; Jacobs, Laurence J.; Kurtis, Kimberly E.

2008-02-01

This research focuses on the application of ultrasonic Rayleigh surface waves to nondestructively characterize the mechanical properties and structural defects (non-uniformly distributed aggregate) in asphalt concrete. An efficient wedge technique is developed in this study to generate Rayleigh surface waves that is shown to be effective in characterizing Rayleigh waves in this highly viscoelastic (attenuating) and heterogeneous medium. Experiments are performed on an asphalt-concrete beam produced with uniformly distributed aggregate. Ultrasonic techniques using both contact and non-contact sensors are examined and their results are compared. Experimental results show that the wedge technique along with an air-coupled sensor appears to be effective in characterizing Rayleigh waves in asphalt concrete. Hence, measurement of theses material properties needs to be investigated in non-uniformly distributed aggregate material using these techniques.

Development and Evaluation of A Novel and Cost-Effective Approach for Low-Cost NO2 Sensor Drift Correction

PubMed Central

Sun, Li; Westerdahl, Dane; Ning, Zhi

2017-01-01

Emerging low-cost gas sensor technologies have received increasing attention in recent years for air quality measurements due to their small size and convenient deployment. However, in the diverse applications these sensors face many technological challenges, including sensor drift over long-term deployment that cannot be easily addressed using mathematical correction algorithms or machine learning methods. This study aims to develop a novel approach to auto-correct the drift of commonly used electrochemical nitrogen dioxide (NO2) sensor with comprehensive evaluation of its application. The impact of environmental factors on the NO2 electrochemical sensor in low-ppb concentration level measurement was evaluated in laboratory and the temperature and relative humidity correction algorithm was evaluated. An automated zeroing protocol was developed and assessed using a chemical absorbent to remove NO2 as a means to perform zero correction in varying ambient conditions. The sensor system was operated in three different environments in which data were compared to a reference NO2 analyzer. The results showed that the zero-calibration protocol effectively corrected the observed drift of the sensor output. This technique offers the ability to enhance the performance of low-cost sensor based systems and these findings suggest extension of the approach to improve data quality from sensors measuring other gaseous pollutants in urban air. PMID:28825633

Applications of wireless sensor networks in marine environment monitoring: a survey.

PubMed

Xu, Guobao; Shen, Weiming; Wang, Xianbin

2014-09-11

With the rapid development of society and the economy, an increasing number of human activities have gradually destroyed the marine environment. Marine environment monitoring is a vital problem and has increasingly attracted a great deal of research and development attention. During the past decade, various marine environment monitoring systems have been developed. The traditional marine environment monitoring system using an oceanographic research vessel is expensive and time-consuming and has a low resolution both in time and space. Wireless Sensor Networks (WSNs) have recently been considered as potentially promising alternatives for monitoring marine environments since they have a number of advantages such as unmanned operation, easy deployment, real-time monitoring, and relatively low cost. This paper provides a comprehensive review of the state-of-the-art technologies in the field of marine environment monitoring using wireless sensor networks. It first describes application areas, a common architecture of WSN-based oceanographic monitoring systems, a general architecture of an oceanographic sensor node, sensing parameters and sensors, and wireless communication technologies. Then, it presents a detailed review of some related projects, systems, techniques, approaches and algorithms. It also discusses challenges and opportunities in the research, development, and deployment of wireless sensor networks for marine environment monitoring.

Advances in miniature spectrometer and sensor development

NASA Astrophysics Data System (ADS)

Malinen, Jouko; Rissanen, Anna; Saari, Heikki; Karioja, Pentti; Karppinen, Mikko; Aalto, Timo; Tukkiniemi, Kari

2014-05-01

Miniaturization and cost reduction of spectrometer and sensor technologies has great potential to open up new applications areas and business opportunities for analytical technology in hand held, mobile and on-line applications. Advances in microfabrication have resulted in high-performance MEMS and MOEMS devices for spectrometer applications. Many other enabling technologies are useful for miniature analytical solutions, such as silicon photonics, nanoimprint lithography (NIL), system-on-chip, system-on-package techniques for integration of electronics and photonics, 3D printing, powerful embedded computing platforms, networked solutions as well as advances in chemometrics modeling. This paper will summarize recent work on spectrometer and sensor miniaturization at VTT Technical Research Centre of Finland. Fabry-Perot interferometer (FPI) tunable filter technology has been developed in two technical versions: Piezoactuated FPIs have been applied in miniature hyperspectral imaging needs in light weight UAV and nanosatellite applications, chemical imaging as well as medical applications. Microfabricated MOEMS FPIs have been developed as cost-effective sensor platforms for visible, NIR and IR applications. Further examples of sensor miniaturization will be discussed, including system-on-package sensor head for mid-IR gas analyzer, roll-to-roll printed Surface Enhanced Raman Scattering (SERS) technology as well as UV imprinted waveguide sensor for formaldehyde detection.

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

Rapid, ultrasensitive detection of microorganisms based on interferometry and lab-on-a-chip nanotechnology

NASA Astrophysics Data System (ADS)

Ymeti, Aurel; Nederkoorn, Paul H. J.; Dudia, Alma; Subramaniam, Vinod; Kanger, Johannes S.

2009-05-01

Future viral outbreaks are a major threat to societal and economic development throughout the world. A rapid, sensitive, and easy-to-use test for viral infections is essential to prevent and to control such viral pandemics. Furthermore, a compact, portable device is potentially very useful in remote or developing regions without easy access to sophisticated laboratory facilities. We have developed a rapid, ultrasensitive sensor that could be used in a handheld device to detect various viruses and measure their concentration. The essential innovation in this technique is the combination of an integrated optical interferometric sensor with antibody-antigen recognition approaches to yield a very sensitive, very rapid test for virus detection. The sensor is able to spot the herpes virus at concentrations of just 850 particles per milliliter under physiological conditions. The sensitivity of the sensor approaches detection of a single virus particle, yielding a sensor of unprecedented sensitivity with wide applications for viral diagnostics. The sensor's detection principle can be extended to any biological target such as bacteria, cells and proteins and for which there are specific antibodies. The nature of the sensor enables multiplexed detection of several analytes at the same time.

Development of a belt-type wearable sensor system with multi-function for home health care

NASA Astrophysics Data System (ADS)

Ban, Yunho; Choi, Samjin; Jiang, Zhongwei; Park, Chanwon

2005-12-01

Some reports show that the physiological information measured in hospital is not enough without the one measured in home. The physiological information monitored in home, therefore, is strongly required recently. The goal of this research is to develop a wearable and tractable sensor system for detecting biomedical signals such as cardiac rhythm, respiration, body movement, and percentage of body fat (%BF) and for home health care. A belt type sensor for this purpose is developed, which consists of sensing materials of PVDF film and conductive fabrics. Also several data processing techniques, such as the discrete wavelet transform, cross correlation and adaptive filtering method, were introduced to eliminate noises and base wandering and to extract the specified components. The ECG and respiration signals obtained by the proposed belt type sensor system gave good agreements with commercial medical system. Furthermore, the body fat (%BF) measurement based on the four-electrode BIA was also built in the belt sensor. The body fat was calculated by measuring the body impedance from the belt type sensor and compared with the predicted %BF measured by the commercial adipometer (TBF-607). The results validated also the efficiency of the belt type sensor system.

First evidence of phase-contrast imaging with laboratory sources and active pixel sensors

NASA Astrophysics Data System (ADS)

Olivo, A.; Arvanitis, C. D.; Bohndiek, S. E.; Clark, A. T.; Prydderch, M.; Turchetta, R.; Speller, R. D.

2007-11-01

The aim of the present work is to achieve a first step towards combining the advantages of an innovative X-ray imaging technique—phase-contrast imaging (XPCi)—with those of a new class of sensors, i.e. CMOS-based active pixel sensors (APSs). The advantages of XPCi are well known and include increased image quality and detection of details invisible to conventional techniques, with potential application fields encompassing the medical, biological, industrial and security areas. Vanilla, one of the APSs developed by the MI-3 collaboration (see http://mi3.shef.ac.uk), was thoroughly characterised and an appropriate scintillator was selected to provide X-ray sensitivity. During this process, a set of phase-contrast images of different biological samples was acquired by means of the well-established free-space propagation XPCi technique. The obtained results are very encouraging and are in optimum agreement with the predictions of a simulation recently developed by some of the authors thus further supporting its reliability. This paper presents these preliminary results in detail and discusses in brief both the background to this work and its future developments.

Reduced-Order Modeling and Wavelet Analysis of Turbofan Engine Structural Response Due to Foreign Object Damage (FOD) Events

NASA Technical Reports Server (NTRS)

Turso, James; Lawrence, Charles; Litt, Jonathan

2004-01-01

The development of a wavelet-based feature extraction technique specifically targeting FOD-event induced vibration signal changes in gas turbine engines is described. The technique performs wavelet analysis of accelerometer signals from specified locations on the engine and is shown to be robust in the presence of significant process and sensor noise. It is envisioned that the technique will be combined with Kalman filter thermal/health parameter estimation for FOD-event detection via information fusion from these (and perhaps other) sources. Due to the lack of high-frequency FOD-event test data in the open literature, a reduced-order turbofan structural model (ROM) was synthesized from a finite element model modal analysis to support the investigation. In addition to providing test data for algorithm development, the ROM is used to determine the optimal sensor location for FOD-event detection. In the presence of significant noise, precise location of the FOD event in time was obtained using the developed wavelet-based feature.

Reduced-Order Modeling and Wavelet Analysis of Turbofan Engine Structural Response Due to Foreign Object Damage "FOD" Events

NASA Technical Reports Server (NTRS)

Turso, James A.; Lawrence, Charles; Litt, Jonathan S.

2007-01-01

The development of a wavelet-based feature extraction technique specifically targeting FOD-event induced vibration signal changes in gas turbine engines is described. The technique performs wavelet analysis of accelerometer signals from specified locations on the engine and is shown to be robust in the presence of significant process and sensor noise. It is envisioned that the technique will be combined with Kalman filter thermal/ health parameter estimation for FOD-event detection via information fusion from these (and perhaps other) sources. Due to the lack of high-frequency FOD-event test data in the open literature, a reduced-order turbofan structural model (ROM) was synthesized from a finite-element model modal analysis to support the investigation. In addition to providing test data for algorithm development, the ROM is used to determine the optimal sensor location for FOD-event detection. In the presence of significant noise, precise location of the FOD event in time was obtained using the developed wavelet-based feature.

Electric field feedback for Magneto(elasto)Electric magnetometer development

NASA Astrophysics Data System (ADS)

Yang, M.-T.; Zhuang, X.; Sing, M. Lam Chok; Dolabdjian, C.; Finkel, P.; Li, J.; Viehland, D.

2017-12-01

Magneto(elasto)Electric (ME) sensors based on magnetostrictive-piezoelectric composites have been investigated to evaluate their performances to sense a magnetic signal. Previous results have shown that the dielectric loss noise in the piezoelectric layer exhibits as the dominant intrinsic noise at low frequencies, which limits the sensor performances. Also, it has intrinsically no DC capability. To avoid a part of this limitation, modulation detection methods are evaluated through a frequency up-conversion technique [1-4]. Moreover, classical magnetic field feedback techniques can be used to increase the dynamic range, the sensing stability and the system linearity, too. In this paper, we propose a new method to feedback the system by using both the magneto-capacitance modulation and an electric field feedback technique. Our development shows the feasibility of the method and the results match with the theoretical description and material properties. Even if the present results are not totally satisfactory, they give the proof of concept and yield a way for the development of very low power magnetometers.

Advances in multi-sensor data fusion: algorithms and applications.

PubMed

Dong, Jiang; Zhuang, Dafang; Huang, Yaohuan; Fu, Jingying

2009-01-01

With the development of satellite and remote sensing techniques, more and more image data from airborne/satellite sensors have become available. Multi-sensor image fusion seeks to combine information from different images to obtain more inferences than can be derived from a single sensor. In image-based application fields, image fusion has emerged as a promising research area since the end of the last century. The paper presents an overview of recent advances in multi-sensor satellite image fusion. Firstly, the most popular existing fusion algorithms are introduced, with emphasis on their recent improvements. Advances in main applications fields in remote sensing, including object identification, classification, change detection and maneuvering targets tracking, are described. Both advantages and limitations of those applications are then discussed. Recommendations are addressed, including: (1) Improvements of fusion algorithms; (2) Development of "algorithm fusion" methods; (3) Establishment of an automatic quality assessment scheme.

Incorporating signal-dependent noise for hyperspectral target detection

NASA Astrophysics Data System (ADS)

Morman, Christopher J.; Meola, Joseph

2015-05-01

The majority of hyperspectral target detection algorithms are developed from statistical data models employing stationary background statistics or white Gaussian noise models. Stationary background models are inaccurate as a result of two separate physical processes. First, varying background classes often exist in the imagery that possess different clutter statistics. Many algorithms can account for this variability through the use of subspaces or clustering techniques. The second physical process, which is often ignored, is a signal-dependent sensor noise term. For photon counting sensors that are often used in hyperspectral imaging systems, sensor noise increases as the measured signal level increases as a result of Poisson random processes. This work investigates the impact of this sensor noise on target detection performance. A linear noise model is developed describing sensor noise variance as a linear function of signal level. The linear noise model is then incorporated for detection of targets using data collected at Wright Patterson Air Force Base.

Privacy-protecting video surveillance

NASA Astrophysics Data System (ADS)

Wickramasuriya, Jehan; Alhazzazi, Mohanned; Datt, Mahesh; Mehrotra, Sharad; Venkatasubramanian, Nalini

2005-02-01

Forms of surveillance are very quickly becoming an integral part of crime control policy, crisis management, social control theory and community consciousness. In turn, it has been used as a simple and effective solution to many of these problems. However, privacy-related concerns have been expressed over the development and deployment of this technology. Used properly, video cameras help expose wrongdoing but typically come at the cost of privacy to those not involved in any maleficent activity. This work describes the design and implementation of a real-time, privacy-protecting video surveillance infrastructure that fuses additional sensor information (e.g. Radio-frequency Identification) with video streams and an access control framework in order to make decisions about how and when to display the individuals under surveillance. This video surveillance system is a particular instance of a more general paradigm of privacy-protecting data collection. In this paper we describe in detail the video processing techniques used in order to achieve real-time tracking of users in pervasive spaces while utilizing the additional sensor data provided by various instrumented sensors. In particular, we discuss background modeling techniques, object tracking and implementation techniques that pertain to the overall development of this system.

Acoustic Techniques for Structural Health Monitoring

NASA Astrophysics Data System (ADS)

Frankenstein, B.; Augustin, J.; Hentschel, D.; Schubert, F.; Köhler, B.; Meyendorf, N.

2008-02-01

Future safety and maintenance strategies for industrial components and vehicles are based on combinations of monitoring systems that are permanently attached to or embedded in the structure, and periodic inspections. The latter belongs to conventional nondestructive evaluation (NDE) and can be enhanced or partially replaced by structural health monitoring systems. However, the main benefit of this technology for the future will consist of systems that can be differently designed based on improved safety philosophies, including continuous monitoring. This approach will increase the efficiency of inspection procedures at reduced inspection times. The Fraunhofer IZFP Dresden Branch has developed network nodes, miniaturized transmitter and receiver systems for active and passive acoustical techniques and sensor systems that can be attached to or embedded into components or structures. These systems have been used to demonstrate intelligent sensor networks for the monitoring of aerospace structures, railway systems, wind energy generators, piping system and other components. Material discontinuities and flaws have been detected and monitored during full scale fatigue testing. This paper will discuss opportunities and future trends in nondestructive evaluation and health monitoring based on new sensor principles and advanced microelectronics. It will outline various application examples of monitoring systems based on acoustic techniques and will indicate further needs for research and development.

A Survey on Optimal Signal Processing Techniques Applied to Improve the Performance of Mechanical Sensors in Automotive Applications

PubMed Central

Hernandez, Wilmar

2007-01-01

In this paper a survey on recent applications of optimal signal processing techniques to improve the performance of mechanical sensors is made. Here, a comparison between classical filters and optimal filters for automotive sensors is made, and the current state of the art of the application of robust and optimal control and signal processing techniques to the design of the intelligent (or smart) sensors that today's cars need is presented through several experimental results that show that the fusion of intelligent sensors and optimal signal processing techniques is the clear way to go. However, the switch between the traditional methods of designing automotive sensors and the new ones cannot be done overnight because there are some open research issues that have to be solved. This paper draws attention to one of the open research issues and tries to arouse researcher's interest in the fusion of intelligent sensors and optimal signal processing techniques.

Development, fabrication, and modeling of highly sensitive conjugated polymer based piezoresistive sensors in electronic skin applications

NASA Astrophysics Data System (ADS)

Khalili, Nazanin; Naguib, Hani E.; Kwon, Roy H.

2016-04-01

Human intervention can be replaced through development of tools resulted from utilizing sensing devices possessing a wide range of applications including humanoid robots or remote and minimally invasive surgeries. Similar to the five human senses, sensors interface with their surroundings to stimulate a suitable response or action. The sense of touch which arises in human skin is among the most challenging senses to emulate due to its ultra high sensitivity. This has brought forth novel challenging issues to consider in the field of biomimetic robotics. In this work, using a multiphase reaction, a polypyrrole (PPy) based hydrogel is developed as a resistive type pressure sensor with an intrinsically elastic microstructure stemming from three dimensional hollow spheres. Furthermore, a semi-analytical constriction resistance model accounting for the real contact area between the PPy hydrogel sensors and the electrode along with the dependency of the contact resistance change on the applied load is developed. The model is then solved using a Monte Carlo technique and the sensitivity of the sensor is obtained. The experimental results showed the good tracking ability of the proposed model.

Fiber-Optical Sensors: Basics and Applications in Multiphase Reactors

PubMed Central

Li, Xiangyang; Yang, Chao; Yang, Shifang; Li, Guozheng

2012-01-01

This work presents a brief introduction on the basics of fiber-optical sensors and an overview focused on the applications to measurements in multiphase reactors. The most commonly principle utilized is laser back scattering, which is also the foundation for almost all current probes used in multiphase reactors. The fiber-optical probe techniques in two-phase reactors are more developed than those in three-phase reactors. There are many studies on the measurement of gas holdup using fiber-optical probes in three-phase fluidized beds, but negative interference of particles on probe function was less studied. The interactions between solids and probe tips were less studied because glass beads etc. were always used as the solid phase. The vision probes may be the most promising for simultaneous measurements of gas dispersion and solids suspension in three-phase reactors. Thus, the following techniques of the fiber-optical probes in multiphase reactors should be developed further: (1) online measuring techniques under nearly industrial operating conditions; (2) corresponding signal data processing techniques; (3) joint application with other measuring techniques.

Development of an integrated sensor module for a non-invasive respiratory monitoring system

NASA Astrophysics Data System (ADS)

Kang, Seok-Won; Chang, Keun-Shik

2013-09-01

A respiratory monitoring system has been developed for analyzing the carbon dioxide (CO2) and oxygen (O2) concentrations in the expired air using gas sensors. The data can be used to estimate some medical conditions, including diffusion capability of the lung membrane, oxygen uptake, and carbon dioxide output. For this purpose, a 3-way valve derived from a servomotor was developed, which operates synchronously with human respiratory signals. In particular, the breath analysis system includes an integrated sensor module for valve control, data acquisition through the O2 and CO2 sensors, and respiratory rate monitoring, as well as software dedicated to analysis of respiratory gasses. In addition, an approximation technique for experimental data based on Haar-wavelet-based decomposition is explored to remove noise as well as to reduce the file size of data for long-term monitoring.

C-MEMS for bio-sensing applications

NASA Astrophysics Data System (ADS)

Song, Yin; Agrawal, Richa; Wang, Chunlei

2015-05-01

Developing highly sensitive, selective, and reproducible miniaturized bio-sensing platforms require reliable biointerface which should be compatible with microfabrication techniques. In this study, we have fabricated pyrolyzed carbon arrays with high surface area as a bio-sensing electrode, and developed the surface functionalization methods to increase biomolecules immobilization efficiency and further understand electrochemical phenomena at biointerfaces. The carbon microelectrode arrays with high aspect ratio have been fabricated by carbon microelectromechanical systems (C-MEMS) and nanomaterials such as graphene have been integrated to further increase surface area. To achieve the efficient covalent immobilization of biomolecules, various oxidation and reduction functionalization methods have been investigated. The oxidation treatment in this study includes vacuum ultraviolet, electrochemical activation, UV/Ozone and oxygen RIE. The reduction treatment includes direct amination and diazonium grafting. The developed bio-sensing platform was then applied for several applications, such as: DNA sensor; H2O2 sensor; aptamer sensor and HIV sensor.

Visualization of stress wave propagation via air-coupled acoustic emission sensors

NASA Astrophysics Data System (ADS)

Rivey, Joshua C.; Lee, Gil-Yong; Yang, Jinkyu; Kim, Youngkey; Kim, Sungchan

2017-02-01

We experimentally demonstrate the feasibility of visualizing stress waves propagating in plates using air-coupled acoustic emission sensors. Specifically, we employ a device that embeds arrays of microphones around an optical lens in a helical pattern. By implementing a beamforming technique, this remote sensing system allows us to record wave propagation events in situ via a single-shot and full-field measurement. This is a significant improvement over the conventional wave propagation tracking approaches based on laser doppler vibrometry or digital image correlation techniques. In this paper, we focus on demonstrating the feasibility and efficacy of this air-coupled acoustic emission technique by using large metallic plates exposed to external impacts. The visualization results of stress wave propagation will be shown under various impact scenarios. The proposed technique can be used to characterize and localize damage by detecting the attenuation, reflection, and scattering of stress waves that occurs at damage locations. This can ultimately lead to the development of new structural health monitoring and nondestructive evaluation methods for identifying hidden cracks or delaminations in metallic or composite plate structures, simultaneously negating the need for mounted contact sensors.

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

Mou, J.I.; King, C.

The focus of this study is to develop a sensor fused process modeling and control methodology to model, assess, and then enhance the performance of a hexapod machine for precision product realization. Deterministic modeling technique was used to derive models for machine performance assessment and enhancement. Sensor fusion methodology was adopted to identify the parameters of the derived models. Empirical models and computational algorithms were also derived and implemented to model, assess, and then enhance the machine performance. The developed sensor fusion algorithms can be implemented on a PC-based open architecture controller to receive information from various sensors, assess themore » status of the process, determine the proper action, and deliver the command to actuators for task execution. This will enhance a hexapod machine`s capability to produce workpieces within the imposed dimensional tolerances.« less

Acoustic emission signal processing technique to characterize reactor in-pile phenomena

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

Agarwal, Vivek, E-mail: vivek.agarwal@inl.gov; Tawfik, Magdy S., E-mail: magdy.tawfik@inl.gov; Smith, James A., E-mail: james.smith@inl.gov

2015-03-31

Existing and developing advanced sensor technologies and instrumentation will allow non-intrusive in-pile measurement of temperature, extension, and fission gases when coupled with advanced signal processing algorithms. The transmitted measured sensor signals from inside to the outside of containment structure are corrupted by noise and are attenuated, thereby reducing the signal strength and the signal-to-noise ratio. Identification and extraction of actual signal (representative of an in-pile phenomenon) is a challenging and complicated process. In the paper, empirical mode decomposition technique is utilized to reconstruct actual sensor signal by partially combining intrinsic mode functions. Reconstructed signal will correspond to phenomena and/or failuremore » modes occurring inside the reactor. In addition, it allows accurate non-intrusive monitoring and trending of in-pile phenomena.« less

Label-free electrical detection of pyrophosphate generated from DNA polymerase reactions on field-effect devices.

PubMed

Credo, Grace M; Su, Xing; Wu, Kai; Elibol, Oguz H; Liu, David J; Reddy, Bobby; Tsai, Ta-Wei; Dorvel, Brian R; Daniels, Jonathan S; Bashir, Rashid; Varma, Madoo

2012-03-21

We introduce a label-free approach for sensing polymerase reactions on deoxyribonucleic acid (DNA) using a chelator-modified silicon-on-insulator field-effect transistor (SOI-FET) that exhibits selective and reversible electrical response to pyrophosphate anions. The chemical modification of the sensor surface was designed to include rolling-circle amplification (RCA) DNA colonies for locally enhanced pyrophosphate (PPi) signal generation and sensors with immobilized chelators for capture and surface-sensitive detection of diffusible reaction by-products. While detecting arrays of enzymatic base incorporation reactions is typically accomplished using optical fluorescence or chemiluminescence techniques, our results suggest that it is possible to develop scalable and portable PPi-specific sensors and platforms for broad biomedical applications such as DNA sequencing and microbe detection using surface-sensitive electrical readout techniques.

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

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

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

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

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

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

NASA Astrophysics Data System (ADS)

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

2018-03-01

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

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

DOE PAGES

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

2018-01-31

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

Synthesis of Novel CuO Nanosheets and Their Non-Enzymatic Glucose Sensing Applications

PubMed Central

Ibupoto, Zafar Hussain; Khun, Kimleang; Beni, Valerio; Liu, Xianjie; Willander, Magnus

2013-01-01

In this study, we have developed a sensitive and selective glucose sensor using novel CuO nanosheets which were grown on a gold coated glass substrate by a low temperature growth method. X-ray differaction (XRD) and scanning electron microscopy (SEM) techniques were used for the structural characterization of CuO nanostructures. CuO nanosheets are highly dense, uniform, and exhibited good crystalline array structure. X-ray photoelectron spectroscopy (XPS) technique was applied for the study of chemical composition of CuO nanosheets and the obtained information demonstrated pure phase CuO nanosheets. The novel CuO nanosheets were employed for the development of a sensitive and selective non-enzymatic glucose sensor. The measured sensitivity and a correlation coefficient are in order 5.20 × 102 μA/mMcm2 and 0.998, respectively. The proposed sensor is associated with several advantages such as low cost, simplicity, high stability, reproducibility and selectivity for the quick detection of glucose. PMID:23787727

Synthesis of novel CuO nanosheets and their non-enzymatic glucose sensing applications.

PubMed

Ibupoto, Zafar Hussain; Khun, Kimleang; Beni, Valerio; Liu, Xianjie; Willander, Magnus

2013-06-20

In this study, we have developed a sensitive and selective glucose sensor using novel CuO nanosheets which were grown on a gold coated glass substrate by a low temperature growth method. X-ray differaction (XRD) and scanning electron microscopy (SEM) techniques were used for the structural characterization of CuO nanostructures. CuO nanosheets are highly dense, uniform, and exhibited good crystalline array structure. X-ray photoelectron spectroscopy (XPS) technique was applied for the study of chemical composition of CuO nanosheets and the obtained information demonstrated pure phase CuO nanosheets. The novel CuO nanosheets were employed for the development of a sensitive and selective non-enzymatic glucose sensor. The measured sensitivity and a correlation coefficient are in order 5.20 × 10² µA/mMcm² and 0.998, respectively. The proposed sensor is associated with several advantages such as low cost, simplicity, high stability, reproducibility and selectivity for the quick detection of glucose.

Nanomanipulation and Lithography for Carbon Nanotube Based Nondestructive Evaluation Sensor Development

NASA Technical Reports Server (NTRS)

Wincheski, Buzz; Smits, Jan; Namkung, Min; Ingram, JoAnne; Watkins, Neal; Jordan, Jeffrey D.; Louie, Richard

2002-01-01

Carbon nanotubes (CNTs) offer great potential for advanced sensor development due to the unique electronic transport properties of the material. However, a significant obstacle to the realization of practical CNT devices is the formation of reliable and reproducible CNT to metallic contacts. In this work, scanning probe techniques are explored for both fabrication of metallic junctions and positioning of singlewalled CNTs across these junctions. The use of a haptic force feedback interface to a scanning probe microscope is used to enable movement of nanotubes over micron length scales with nanometer precision. In this case, imaging of the surface is performed with light or intermittent contact to the surface. Increased tip-to-sample interaction forces are then applied to either create junctions or position CNTs. The effect of functionalization of substrate surfaces on the movement and tribology of the materials is also studied. The application of these techniques to the fabrication of CNT-based sensors for nondestructive evaluation applications is discussed.

Real-time, wide-area hyperspectral imaging sensors for standoff detection of explosives and chemical warfare agents

NASA Astrophysics Data System (ADS)

Gomer, Nathaniel R.; Tazik, Shawna; Gardner, Charles W.; Nelson, Matthew P.

2017-05-01

Hyperspectral imaging (HSI) is a valuable tool for the detection and analysis of targets located within complex backgrounds. HSI can detect threat materials on environmental surfaces, where the concentration of the target of interest is often very low and is typically found within complex scenery. Unfortunately, current generation HSI systems have size, weight, and power limitations that prohibit their use for field-portable and/or real-time applications. Current generation systems commonly provide an inefficient area search rate, require close proximity to the target for screening, and/or are not capable of making real-time measurements. ChemImage Sensor Systems (CISS) is developing a variety of real-time, wide-field hyperspectral imaging systems that utilize shortwave infrared (SWIR) absorption and Raman spectroscopy. SWIR HSI sensors provide wide-area imagery with at or near real time detection speeds. Raman HSI sensors are being developed to overcome two obstacles present in standard Raman detection systems: slow area search rate (due to small laser spot sizes) and lack of eye-safety. SWIR HSI sensors have been integrated into mobile, robot based platforms and handheld variants for the detection of explosives and chemical warfare agents (CWAs). In addition, the fusion of these two technologies into a single system has shown the feasibility of using both techniques concurrently to provide higher probability of detection and lower false alarm rates. This paper will provide background on Raman and SWIR HSI, discuss the applications for these techniques, and provide an overview of novel CISS HSI sensors focusing on sensor design and detection results.

Optical devices for biochemical sensing in flame hydrolysis deposited glass

NASA Astrophysics Data System (ADS)

Ruano-Lopez, Jesus M.

Previous research in the field of Flame Hydrolysis Deposition (FHD) of glasses has focused on the production of low cost optical devices for the field of telecommunications. The originality of this doctoral research resides in the exploration of this technology in the fabrication of optical bio-chemical sensors, with integrated "Lab-on-a-chip" devices. To achieve this goal, we have combined and applied different microfabrication processes for the manufacture of sensor platforms using FHD. These structures are unique in that they take advantage of the intrinsic benefits of the microfabrication process, such as, miniaturisation and mass production, and combine them with the properties of FHD glass, namely: low loss optical transducing mechanisms, planar technologies and monolithic integration. This thesis demonstrates that FHD is a suitable technology for biosensing and Lab- on-a-Chip applications. The objective is to provide future researchers with the necessary tools to accomplish an integrated analytical system based on FHD. We have designed, fabricated, and successfully tested a FHD miniaturised sensor, which comprised optical and microfluidic circuitry, in the framework of low volume fluorescence assays. For the first time, volumes as low as 570 pL were analysed with a Cyanine-5 fluorophore with a detection limit of 20 pM, or ca. 6000 molecules (+/-3sigma) for this platform. The fabrication of the sensor generated a compilation of processes that were then utilised to produce other possible optical platforms for bio-chemical sensors in FHD, e.g. arrays and microfluidics. The "catalogue" of methods used included new recipes for reactive ion etching, glass deposition and bonding techniques that enabled the development of the microfluidic circuitry, integrated with an optical circuitry. Furthermore, we developed techniques to implement new tasks such as optical signal treatment using integrated optical structures, planar arraying of sensors, a separating element for liquid chromatography, and finally a pumping system for delivering small amounts of liquid along the microfluidic channels. This thesis comprises six chapters. In Chapter 1, an overview of the topic was presented, offering a review of the various fields addressed, as well as a description of the motivation and originality of this work. Chapter 2 describes the processes developed to fabricate an optical sensor, and Chapter 3 assesses its performance. In Chapter 4, integrated optical circuit designs and their fabrication methods, as well as developing and testing of an array of sensors, are presented. The description of a separating element involved in a liquid chromatography system, and the pumping of liquids in a FHD optical device, were addressed in Chapter 5. Finally, Chapter 6 summarised the conclusions and suggested possible future work. Last but not least, the appendix, contains techniques for hybrid integration; recipes for etching of rare earth glasses; as well as instrumentation designs. This research has taken Flame Hydrolysis Deposition technique into the world of optical bio-chemical sensors, creating a bridge between analytical assays and FHD glass. In this respect, the demonstrated flexibility of the technology will enable a variety of configurations to be created and implemented, with the prospect of using the techniques for laboratory-on-a-chip technologies. The work has been patented by the University of Glasgow, for future exploitation in analytical biotechnology and Lab-on-a-Chip.

Multispectral system analysis through modeling and simulation

NASA Technical Reports Server (NTRS)

Malila, W. A.; Gleason, J. M.; Cicone, R. C.

1977-01-01

The design and development of multispectral remote sensor systems and associated information extraction techniques should be optimized under the physical and economic constraints encountered and yet be effective over a wide range of scene and environmental conditions. Direct measurement of the full range of conditions to be encountered can be difficult, time consuming, and costly. Simulation of multispectral data by modeling scene, atmosphere, sensor, and data classifier characteristics is set forth as a viable alternative, particularly when coupled with limited sets of empirical measurements. A multispectral system modeling capability is described. Use of the model is illustrated for several applications - interpretation of remotely sensed data from agricultural and forest scenes, evaluating atmospheric effects in Landsat data, examining system design and operational configuration, and development of information extraction techniques.

Multispectral system analysis through modeling and simulation

NASA Technical Reports Server (NTRS)

Malila, W. A.; Gleason, J. M.; Cicone, R. C.

1977-01-01

The design and development of multispectral remote sensor systems and associated information extraction techniques should be optimized under the physical and economic constraints encountered and yet be effective over a wide range of scene and environmental conditions. Direct measurement of the full range of conditions to be encountered can be difficult, time consuming, and costly. Simulation of multispectral data by modeling scene, atmosphere, sensor, and data classifier characteristics is set forth as a viable alternative, particularly when coupled with limited sets of empirical measurements. A multispectral system modeling capability is described. Use of the model is illustrated for several applications - interpretation of remotely sensed data from agricultural and forest scenes, evaluating atmospheric effects in LANDSAT data, examining system design and operational configuration, and development of information extraction techniques.

Development and validation of a sensor-based health monitoring model for the Parkview Bridge deck : [appendices].

DOT National Transportation Integrated Search

2012-01-31

Accelerated bridge construction (ABC) using full-depth precast deck panels is an innovative technique that brings all the benefits listed under ABC to full fruition. However, this technique needs to be evaluated and the performance of the bridge need...

Study on RC beams using BOTDA(R)-FRP-OF technique

NASA Astrophysics Data System (ADS)

He, Jianping; Zhou, Zhi; Huang, Ying; Ou, Jinping

2008-03-01

Brillouin based fiber optic sensing turns to be a promising technology for Structural Health Monitoring (SHM). However, the bare optical fiber is too fragile to act as a practical sensor, so high durability and large range (large strain) Brillouin distributed sensors are in great needs in field applications. For this reason, high durable and large range optical fiber Brillouin Optical Time Domain Analysis sensors packaged by Fiber Reinforcement Polymer (FRP), named BOTDA(R)-FRP-OF, have been studied and developed. Besides, in order to study the large strain, crack and slip between the rebar and concrete in reinforced concrete (RC) beams using BOTDR(A) technique, two RC Beams installed with BOTDA(R)-FRP-OF sensors have been set up. And the damage characteristics of the RC beams were investigated by comparing the strain measured by the BOTDA(R)-FRP-OF sensors and the strain from traditional electric strain gauges. The test results show that the BOTDA(R)-FRP-OF sensor can effectively detect the damage (including crack and slip) characteristic of RC beam, and it is suitable for the long-term structural health monitoring on concrete structures such as bridge, big dam and so on.

A review of sensors, samplers and methods for marine biological observations.

NASA Astrophysics Data System (ADS)

Simmons, S. E.; Chavez, F.; Pearlman, J.; Working Group, T B S

2016-02-01

Physical scientists now have Argo floats, gliders and AUVs to supplement satellites to provide a 3-D view of the time-varying global ocean temperature and salinity structure. Biogeochemists are catching up with evolving sensors for nitrate, optical properties, oxygen and pH that can now be added to these autonomous systems. Biologists are still lagging, although some promising sensor systems based on but not limited to acoustic, chemical, genomic or imaging techniques, that can sense from microbes to whales, are on the horizon. These techniques can not only be applied in situ but also on samples returned to the laboratory using the autonomous systems. The number of samples is limiting, requiring adaptive and smart systems. Given the importance of biology to ocean health and the future earth, and the present reliance on humans and ships for observing species and abundance it is paramount that new biological sensor systems be developed. This abstract will review recent efforts to identify core biological variables for the US Integrated Ocean Observing System and address new sensors and innovations for observing these variables, particularly focused on availability and maturity of sensors. The relevance of this work in a global context will also be touched on.

Fiber optic sensors and systems at the Federal University of Rio de Janeiro

NASA Astrophysics Data System (ADS)

Werneck, Marcelo M.; dos Santos, Paulo A. M.; Ferreira, Aldo P.; Maggi, Luis E.; de Carvalho, Carlos R., Jr.; Ribeiro, R. M.

1998-08-01

As widely known, fiberoptics (FO) are being used in a large variety of sensors and systems particularly for their small dimensions and low cost, large bandwidth and favorable dielectric properties. These properties have allowed us to develop sensors and systems for general applications and, particularly, for biomedical engineering. The intravascular pressure sensor was designed for small dimensions and high bandwidth. The system is based on light-intensity modulation technique and uses a 2 mm-diameter elastomer membrane as the sensor element and a pigtailed laser as a light source. The optical power output curve was linear for pressures within the range of 0 to 300 mmHg. The real time optical biosensor uses the evanescent field technique for monitoring Escherichia coli growth in culture media. The optical biosensor monitors interactions between the analytic (bacteria) and the evanescent field of an optical fiber passing through it. The FO based high voltage and current sensor is a measuring system designed for monitoring voltage and current in high voltage transmission lines. The linearity of the system is better than 2% in both ranges of 0 to 25 kV and 0 to 1000 A. The optical flowmeter uses a cross-correlation technique that analyses two light beams crossing the flow separated by a fixed distance. The x-ray image sensor uses a scintillating FO array, one FO for each image pixel to form an image of the x-ray field. The systems described in these paper use general-purpose components including optical fibers and optoelectronic devices, which are readily available, and of low cost.

Research progress in fiber optic sensors and systems at the Federal University of Rio de Janeiro

NASA Astrophysics Data System (ADS)

Werneck, Marcelo M.; Ferreira, Aldo P.; Maggi, Luis E.; De Carvalho, C. C.; Ribeiro, R. M.

1999-02-01

As widely known, fiberoptics (FO) are being used in a large variety of sensor an systems particularly for their small dimensions and low cost, large bandwidth and favorable dielectric properties. These properties have allowed us to develop sensor and systems for general applications and, particularly, for biomedical engineering. The intravasculator pressure sensor was designed for small dimensions and high bandwidth. The system is based on light- intensity modulation technique and use a 2 mm-diameter elastomer membrane as the sensor element and a pigtailed laser as a light source. The optical power out put curve was linear for pressures within the range of 0 to 300 mmHg. The real time optical biosensor uses the evanescent field technique for monitoring Escherichia coli growth in culture media. The optical biosensor monitors interactions between the analytic and the evanescent field of an optical fiber passing through it. The FO based high voltage and current sensor is a measuring system designed for monitoring voltage and current in high voltage transmission lines. The linearity of the system is better than 2 percent in both ranges of 0 to 25 kV and 0 to 1000 A. The optical flowmeter uses a cross-correlation technique that analyzes two light beams crossing the flow separated by a fixed distance. The x-ray image sensor uses a scintillating FO array, one FO for each image pixel to form an image of the x-ray field. The systems described in this paper use general-purpose components including optical fibers and optoelectronic devices, which are readily available, and of low cost.

Early-age monitoring of cement structures using FBG sensors

NASA Astrophysics Data System (ADS)

Wang, Chuan; Zhou, Zhi; Zhang, Zhichun; Ou, Jinping

2006-03-01

With more and more broad applications of the cement-based structures such as neat cement paste, cement mortar and concrete in civil engineering, people hope to find out what their performances should like. The in-service performances of cement-based structures are highly affected by their hardening process during the early-age. But it is still a big problem for traditional sensors to be used to monitor the early curing of cement-based structures due to such disadvantages as difficulties to install sensors inside the concrete, limited measuring points, poor durability and interference of electromagnetic wave and so on. In this paper, according to the sensing properties of the Fiber Bragg Grating sensors and self-characters of the cement-based structures, we have successfully finished measuring and monitoring the early-age inner-strain and temperature changes of the neat cement paste, concrete with and without restrictions, mass concrete structures and negative concrete, respectively. Three types of FBG-based sensors have been developed to monitor the cement-based structures. Besides, the installation techniques and the embedding requirements of FBG sensors in cement-based structures are also discussed. Moreover, such kind of technique has been used in practical structure, 3rd Nanjing Yangtze Bridge, and the results show that FBG sensors are well proper for measuring and monitoring the temperature and strain changes including self-shrinkage, dry shrinkage, plastic shrinkage, temperature expansion, frost heaving and so on inside different cement-based structures. This technique provides us a new useful measuring method on early curing monitoring of cement-based structures and greater understanding of details of their hardening process.

Signal processing methods for MFE plasma diagnostics

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

Candy, J.V.; Casper, T.; Kane, R.

1985-02-01

The application of various signal processing methods to extract energy storage information from plasma diamagnetism sensors occurring during physics experiments on the Tandom Mirror Experiment-Upgrade (TMX-U) is discussed. We show how these processing techniques can be used to decrease the uncertainty in the corresponding sensor measurements. The algorithms suggested are implemented using SIG, an interactive signal processing package developed at LLNL.

Smart sensing of aviation structures with fiber optic Bragg grating sensors

NASA Astrophysics Data System (ADS)

Trutzel, Michael N.; Wauer, Karsten; Betz, Daniel; Staudigel, Lothar; Krumpholz, Oskar; Muehlmann, Hans-Christian; Muellert, Thomas; Gleine, Wolfgang

2000-06-01

We developed a surface mounting technique where fiber-optic Bragg grating (FBG) sensors are glued to the surface of structures and tested the technique on the surface of a CFRP- wing at the DASA Airbus test center Hamburg for over one year. The FBG sensors were interrogated with a measurement system capable of determining the Bragg wavelength in a few seconds over a spectral range of 60 nm (around 1.53 μm) with an absolute accuracy better than 1 pm. A polarization scrambler was used to account for polarization effects. Excellent consistence between the values of electrical strain gauges and the FBG sensors were found during all measurements. However because this method shows drawbacks in a harsher environment such as a flight test, we are currently investigating the possibilities of integrating FBG sensors into the varnish of the structures. For reasons of their better mechanical performance we use FBG sensors produced on the fiber draw-tower with a special UV-curable coating. The sensors are integrated into an original Airbus varnish build- up. We observed linear strain sensitivities in a temperature range between -50 and +100 °C. Furthermore, at negative temperatures we found a vanish- induced polarization dependence which could be used to differentiate between strain and temperature effects.

Pairwise graphical models for structural health monitoring with dense sensor arrays

NASA Astrophysics Data System (ADS)

Mohammadi Ghazi, Reza; Chen, Justin G.; Büyüköztürk, Oral

2017-09-01

Through advances in sensor technology and development of camera-based measurement techniques, it has become affordable to obtain high spatial resolution data from structures. Although measured datasets become more informative by increasing the number of sensors, the spatial dependencies between sensor data are increased at the same time. Therefore, appropriate data analysis techniques are needed to handle the inference problem in presence of these dependencies. In this paper, we propose a novel approach that uses graphical models (GM) for considering the spatial dependencies between sensor measurements in dense sensor networks or arrays to improve damage localization accuracy in structural health monitoring (SHM) application. Because there are always unobserved damaged states in this application, the available information is insufficient for learning the GMs. To overcome this challenge, we propose an approximated model that uses the mutual information between sensor measurements to learn the GMs. The study is backed by experimental validation of the method on two test structures. The first is a three-story two-bay steel model structure that is instrumented by MEMS accelerometers. The second experimental setup consists of a plate structure and a video camera to measure the displacement field of the plate. Our results show that considering the spatial dependencies by the proposed algorithm can significantly improve damage localization accuracy.

Fiber optic sensors; Proceedings of the Meeting, Cannes, France, November 26, 27, 1985

NASA Technical Reports Server (NTRS)

Arditty, Herve J. (Editor); Jeunhomme, Luc B. (Editor)

1986-01-01

The conference presents papers on distributed sensors and sensor networks, signal processing and detection techniques, temperature measurements, chemical sensors, and the measurement of pressure, strain, and displacements. Particular attention is given to optical fiber distributed sensors and sensor networks, tactile sensing in robotics using an optical network and Z-plane techniques, and a spontaneous Raman temperature sensor. Other topics include coherence in optical fiber gyroscopes, a high bandwidth two-phase flow void fraction fiber optic sensor, and a fiber-optic dark-field microbend sensor.

Progress in Insect-Inspired Optical Navigation Sensors

NASA Technical Reports Server (NTRS)

Thakoor, Sarita; Chahl, Javaan; Zometzer, Steve

2005-01-01

Progress has been made in continuing efforts to develop optical flight-control and navigation sensors for miniature robotic aircraft. The designs of these sensors are inspired by the designs and functions of the vision systems and brains of insects. Two types of sensors of particular interest are polarization compasses and ocellar horizon sensors. The basic principle of polarization compasses was described (but without using the term "polarization compass") in "Insect-Inspired Flight Control for Small Flying Robots" (NPO-30545), NASA Tech Briefs, Vol. 29, No. 1 (January 2005), page 61. To recapitulate: Bees use sky polarization patterns in ultraviolet (UV) light, caused by Rayleigh scattering of sunlight by atmospheric gas molecules, as direction references relative to the apparent position of the Sun. A robotic direction-finding technique based on this concept would be more robust in comparison with a technique based on the direction to the visible Sun because the UV polarization pattern is distributed across the entire sky and, hence, is redundant and can be extrapolated from a small region of clear sky in an elsewhere cloudy sky that hides the Sun.

Remotely deployable aerial inspection using tactile sensors

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

MacLeod, C. N.; Cao, J.; Pierce, S. G.

For structural monitoring applications, the use of remotely deployable Non-Destructive Evaluation (NDE) inspection platforms offer many advantages, including improved accessibility, greater safety and reduced cost, when compared to traditional manual inspection techniques. The use of such platforms, previously reported by researchers at the University Strathclyde facilitates the potential for rapid scanning of large areas and volumes in hazardous locations. A common problem for both manual and remote deployment approaches lies in the intrinsic stand-off and surface coupling issues of typical NDE probes. The associated complications of these requirements are obviously significantly exacerbated when considering aerial based remote inspection and deployment,more » resulting in simple visual techniques being the preferred sensor payload. Researchers at Bristol Robotics Laboratory have developed biomimetic tactile sensors modelled on the facial whiskers (vibrissae) of animals such as rats and mice, with the latest sensors actively sweeping their tips across the surface in a back and forth motion. The current work reports on the design and performance of an aerial inspection platform and the suitability of tactile whisking sensors to aerial based surface monitoring applications.« less

A Comparison of Alternative Distributed Dynamic Cluster Formation Techniques for Industrial Wireless Sensor Networks.

PubMed

Gholami, Mohammad; Brennan, Robert W

2016-01-06

In this paper, we investigate alternative distributed clustering techniques for wireless sensor node tracking in an industrial environment. The research builds on extant work on wireless sensor node clustering by reporting on: (1) the development of a novel distributed management approach for tracking mobile nodes in an industrial wireless sensor network; and (2) an objective comparison of alternative cluster management approaches for wireless sensor networks. To perform this comparison, we focus on two main clustering approaches proposed in the literature: pre-defined clusters and ad hoc clusters. These approaches are compared in the context of their reconfigurability: more specifically, we investigate the trade-off between the cost and the effectiveness of competing strategies aimed at adapting to changes in the sensing environment. To support this work, we introduce three new metrics: a cost/efficiency measure, a performance measure, and a resource consumption measure. The results of our experiments show that ad hoc clusters adapt more readily to changes in the sensing environment, but this higher level of adaptability is at the cost of overall efficiency.

A Comparison of Alternative Distributed Dynamic Cluster Formation Techniques for Industrial Wireless Sensor Networks

PubMed Central

Gholami, Mohammad; Brennan, Robert W.

2016-01-01

In this paper, we investigate alternative distributed clustering techniques for wireless sensor node tracking in an industrial environment. The research builds on extant work on wireless sensor node clustering by reporting on: (1) the development of a novel distributed management approach for tracking mobile nodes in an industrial wireless sensor network; and (2) an objective comparison of alternative cluster management approaches for wireless sensor networks. To perform this comparison, we focus on two main clustering approaches proposed in the literature: pre-defined clusters and ad hoc clusters. These approaches are compared in the context of their reconfigurability: more specifically, we investigate the trade-off between the cost and the effectiveness of competing strategies aimed at adapting to changes in the sensing environment. To support this work, we introduce three new metrics: a cost/efficiency measure, a performance measure, and a resource consumption measure. The results of our experiments show that ad hoc clusters adapt more readily to changes in the sensing environment, but this higher level of adaptability is at the cost of overall efficiency. PMID:26751447

Microsystems in medicine.

PubMed

Wallrabe, U; Ruther, P; Schaller, T; Schomburg, W K

1998-03-01

The complexity of modern surgical and analytical methods requires the miniaturisation of many medical devices. The LIGA technique and also mechanical microengineering are well known for the batch fabrication of microsystems. Actuators and sensors are developed based on these techniques. The hydraulic actuation principle is advantageous for medical applications since the energy may be supplied by pressurised balanced salt solution. Some examples are turbines, pumps and valves. In addition, optical sensors and components are useful for analysis and inspection as represented by microspectrometers and spherical lenses. Finally, plastic containers with microporous bottoms allow a 3-dimensional growth of cell culture systems.

Nitric oxide selective electrodes.

PubMed

Davies, Ian R; Zhang, Xueji

2008-01-01

Since nitric oxide (NO) was identified as the endothelial-derived relaxing factor in the late 1980s, many approaches have attempted to provide an adequate means for measuring physiological levels of NO. Although several techniques have been successful in achieving this aim, the electrochemical method has proved the only technique that can reliably measure physiological levels of NO in vitro, in vivo, and in real time. We describe here the development of electrochemical sensors for NO, including the fabrication of sensors, the detection principle, calibration, detection limits, selectivity, and response time. Furthermore, we look at the many experimental applications where NO selective electrodes have been successfully used.

Ultrasonic guided wave interpretation for structural health inspections

NASA Astrophysics Data System (ADS)

Bingham, Jill Paisley

Structural Health Management (SHM) combines the use of onboard sensors with artificial intelligence algorithms to automatically identify and monitor structural health issues. A fully integrated approach to SHM systems demands an understanding of the sensor output relative to the structure, along with sophisticated prognostic systems that automatically draw conclusions about structural integrity issues. Ultrasonic guided wave methods allow us to examine the interaction of multimode signals within key structural components. Since they propagate relatively long distances within plate- and shell-like structures, guided waves allow inspection of greater areas with fewer sensors, making this technique attractive for a variety of applications. This dissertation describes the experimental development of automatic guided wave interpretation for three real world applications. Using the guided wave theories for idealized plates we have systematically developed techniques for identifying the mass loading of underwater limpet mines on US Navy ship hulls, characterizing type and bonding of protective coatings on large diameter pipelines, and detecting the thinning effects of corrosion on aluminum aircraft structural stringers. In each of these circumstances the signals received are too complex for interpretation without knowledge of the guided wave physics. We employ a signal processing technique called the Dynamic Wavelet Fingerprint Technique (DFWT) in order to render the guided wave mode information in two-dimensional binary images. The use of wavelets allows us to keep track of both time and scale features from the original signals. With simple image processing we have developed automatic extraction algorithms for features that correspond to the arrival times of the guided wave modes of interest for each of the applications. Due to the dispersive nature of the guided wave modes, the mode arrival times give details of the structure in the propagation path. For further understanding of how the guided wave modes propagate through the real structures, we have developed parallel processing, 3D elastic wave simulations using the finite integration technique (EFIT). This full field, numeric simulation technique easily examines models too complex for analytical solutions. We have developed the algorithm to handle built up 3D structures as well as layers with different material properties and surface detail. The simulations produce informative visualizations of the guided wave modes in the structures as well as the output from sensors placed in the simulation space to mimic the placement from experiment. Using the previously developed mode extraction algorithms we were then able to compare our 3D EFIT data to their experimental counterparts with consistency.

Fiber optic (flight quality) sensors for advanced aircraft propulsion

NASA Technical Reports Server (NTRS)

Poppel, Gary L.

1994-01-01

Development of flight prototype, fiber-optic sensing system components for measuring nine sensed parameters (three temperatures, two speeds, three positions, and one flame) on an F404-400 aircraft engine is described. Details of each sensor's design, functionality, and environmental testing, and the electro-optics architecture for sensor signal conditioning are presented. Eight different optical sensing techniques were utilized. Design, assembly, and environmental testing of an engine-mounted, electro-optics chassis unit (EOU), providing MIL-C-1553 data output, are related. Interconnection cables and connectors between the EOU and the sensors are identified. Results of sensor/cable/circuitry integrated testing, and installation and ground testing of the sensor system on an engine in October 1993 and April 1994 are given, including comparisons with the engine control system's electrical sensors. Lessons learned about the design, fabrication, testing, and integration of the sensor system components are included.

Development and experimental characterization of a new non contact sensor for blade tip timing

NASA Astrophysics Data System (ADS)

Brouckaert, Jean-Francois; Marsili, Roberto; Rossi, Gianluca; Tomassini, Roberto

2012-06-01

Performances of blade tip timing measurement systems (BTT), recently used for non contact turbine blade vibration measurements, in terms of uncertainty and resolution are strongly affected by sensor characteristics. The sensors used for BTT generate pulses, to be used also for precise measurements of turbine blades time of arrival. All the literature on this measurement techniques do not address this problem in a clear way, defining the relevant dynamic and static sensor characteristics, fundamental for this application. Till now proximity sensors used are based on optical, capacitive, eddy current and microwave measuring principle. Also pressure sensors has been used. In this paper a new sensing principle is proposed. A proximity sensor based on magnetoresistive sensing element has been assembled end tested. A simple and portable test bench with variable speed, blade tip width, variable clearance was built and used in order to characterize the main sensor performances.

Information-based approach to performance estimation and requirements allocation in multisensor fusion for target recognition

NASA Astrophysics Data System (ADS)

Harney, Robert C.

1997-03-01

A novel methodology offering the potential for resolving two of the significant problems of implementing multisensor target recognition systems, i.e., the rational selection of a specific sensor suite and optimal allocation of requirements among sensors, is presented. Based on a sequence of conjectures (and their supporting arguments) concerning the relationship of extractable information content to recognition performance of a sensor system, a set of heuristics (essentially a reformulation of Johnson's criteria applicable to all sensor and data types) is developed. An approach to quantifying the information content of sensor data is described. Coupling this approach with the widely accepted Johnson's criteria for target recognition capabilities results in a quantitative method for comparing the target recognition ability of diverse sensors (imagers, nonimagers, active, passive, electromagnetic, acoustic, etc.). Extension to describing the performance of multiple sensors is straightforward. The application of the technique to sensor selection and requirements allocation is discussed.

Fiber Optic Sensors for Health Monitoring of Morphing Airframes. Part 1; Bragg Grating Strain and Temperature Sensor

NASA Technical Reports Server (NTRS)

Wood, Karen; Brown, Timothy; Rogowski, Robert; Jensen, Brian

2000-01-01

Fiber optic sensors are being developed for health monitoring of future aircraft. Aircraft health monitoring involves the use of strain, temperature, vibration and chemical sensors to infer integrity of the aircraft structure. Part 1 of this two part series describes sensors that will measure load and temperature signatures of these structures. In some cases a single fiber may be used for measuring these parameters. Part 2 will describe techniques for using optical fibers to monitor composite cure in real time during manufacture and to monitor in-service integrity of composite structures using a single fiber optic sensor capable of measuring multiple chemical and physical parameters. The facilities for fabricating optical fiber and associated sensors and the methods of demodulating Bragg gratings for strain measurement will be described.

Fiber-Optic Chemical Sensors and Fiber-Optic Bio-Sensors

PubMed Central

Pospíšilová, Marie; Kuncová, Gabriela; Trögl, Josef

2015-01-01

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

Remote sensing advances in agricultural inventories

NASA Technical Reports Server (NTRS)

Dragg, J. L.; Bizzell, R. M.; Trichel, M. C.; Hatch, R. E.; Phinney, D. E.; Baker, T. C.

1984-01-01

As the complexity of the world's agricultural industry increases, more timely and more accurate world-wide agricultural information is required to support production and marketing decisions, policy formulation, and technology development. The Inventory Technology Development Project of the AgRISTARS Program has developed new automated technology that uses data sets acquired by spaceborne remote sensors. Research has emphasized the development of multistage, multisensor sampling and estimation techniques for use in global environments where reliable ground observations are not available. This paper presents research results obtained from data sets acquired by four different sensors: Landsat MSS, Landsat TM, Shuttle-Imaging Radar and environmental satellite (AVHRR).

AOI [3]: Smart Refractory Sensor Systems for Wireless Monitoring of Temperature, Health, and Degradation of Slagging Gasifiers

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

Sabolsky, Edward M.; Bhattacharyya, Debangsu; Graham, David

The objective of the work was to develop refractory “smart bricks”, which would contain embedded temperature, strain/stress, and spallation sensors throughout the volume of high-chromia (-Cr2O3) refractory brick. The proposed work included work to interconnect the sensors to the reactor exterior, where the sensor signals may be processed by low-power electronics and transmitted wirelessly to a central processing hub. The data processing and wireless transmitter hardware was specifically designed to be isolated (with low power consumption) and to be adaptable to future implementation of energy-harvesting strategies for extended life. Finally, the collected data was incorporated into a model to estimatemore » refractory degradation, a technique that could help monitor the health of the refractory in real-time. The long-term goal of this program was to demonstrate high-temperature, wireless sensor arrays for in situ three-dimensional (3-D) refractory monitoring or mapping for slagging gasification systems. The research was in collaboration with HarbisonWalker International (HWI) Technology Center in West Mifflin, PA. HWI is a leading developer and manufacturer of ceramic refractory products for high-temperature applications. The work completed focused on the following areas: 1) Investigation of the chemical stability, microstructural evolution, grain growth kinetics, degree of homogeneity (quantitative image analysis), and electrical properties of refractory oxide-silicide composites at temperatures between 750-1450ºC; 2) Fabrication of silicide-alumina composite and oxide thermocouples and thermistor preforms and the development of techniques to embed them into high-chromia refractory bricks to form “smart bricks”; 3) Utilization of commercial off-the-shelf discrete components to prototype circuits for interfacing between smart brick sensors and the wireless sensor network. The prototypes were then used to design an integrated circuit for thermistor, thermocouple, and capacitive-based smart brick sensor interfacing; 4) Interfacing of the smart bricks with embedded sensors with wireless motes thus yielding a complete signal chain. This end-to-end data collection system was tested on a furnace heated to 1350 °C; 5) Development of a slag penetration model and a nonlinear unknown input filter for the data from the embedded sensors for estimating temperature and extent of slag penetration.« less

Generic Sensor Modeling Using Pulse Method

NASA Technical Reports Server (NTRS)

Helder, Dennis L.; Choi, Taeyoung

2005-01-01

Recent development of high spatial resolution satellites such as IKONOS, Quickbird and Orbview enable observation of the Earth's surface with sub-meter resolution. Compared to the 30 meter resolution of Landsat 5 TM, the amount of information in the output image was dramatically increased. In this era of high spatial resolution, the estimation of spatial quality of images is gaining attention. Historically, the Modulation Transfer Function (MTF) concept has been used to estimate an imaging system's spatial quality. Sometimes classified by target shapes, various methods were developed in laboratory environment utilizing sinusoidal inputs, periodic bar patterns and narrow slits. On-orbit sensor MTF estimation was performed on 30-meter GSD Landsat4 Thematic Mapper (TM) data from the bridge pulse target as a pulse input . Because of a high resolution sensor s small Ground Sampling Distance (GSD), reasonably sized man-made edge, pulse, and impulse targets can be deployed on a uniform grassy area with accurate control of ground targets using tarps and convex mirrors. All the previous work cited calculated MTF without testing the MTF estimator's performance. In previous report, a numerical generic sensor model had been developed to simulate and improve the performance of on-orbit MTF estimating techniques. Results from the previous sensor modeling report that have been incorporated into standard MTF estimation work include Fermi edge detection and the newly developed 4th order modified Savitzky-Golay (MSG) interpolation technique. Noise sensitivity had been studied by performing simulations on known noise sources and a sensor model. Extensive investigation was done to characterize multi-resolution ground noise. Finally, angle simulation was tested by using synthetic pulse targets with angles from 2 to 15 degrees, several brightness levels, and different noise levels from both ground targets and imaging system. As a continuing research activity using the developed sensor model, this report was dedicated to MTF estimation via pulse input method characterization using the Fermi edge detection and 4th order MSG interpolation method. The relationship between pulse width and MTF value at Nyquist was studied including error detection and correction schemes. Pulse target angle sensitivity was studied by using synthetic targets angled from 2 to 12 degrees. In this report, from the ground and system noise simulation, a minimum SNR value was suggested for a stable MTF value at Nyquist for the pulse method. Target width error detection and adjustment technique based on a smooth transition of MTF profile is presented, which is specifically applicable only to the pulse method with 3 pixel wide targets.

Steel reinforcement corrosion detection with coaxial cable sensors

NASA Astrophysics Data System (ADS)

Muchaidze, Iana; Pommerenke, David; Chen, Genda

2011-04-01

Corrosion processes in the steel reinforced structures can result in structural deficiency and with time create a threat to human lives. Millions of dollars are lost each year because of corrosion. According to the U. S. Federal Highway Administration (FHWA) the average annual cost of corrosion in the infrastructure sector by the end of 2002 was estimated to be $22.6 billion. Timely remediation/retrofit and effective maintenance can extend the structure's live span for much less expense. Thus the considerable effort should be done to deploy corrosion monitoring techniques to have realistic information on the location and the severity of damage. Nowadays commercially available techniques for corrosion monitoring require costly equipment and certain interpretational skills. In addition, none of them is designed for the real time quality assessment. In this study the crack sensor developed at Missouri University of Science and Technology is proposed as a distributed sensor for real time corrosion monitoring. Implementation of this technology may ease the pressure on the bridge owners restrained with the federal budget by allowing the timely remediation with the minimal financial and labor expenses. The sensor is instrumented in such a way that the location of any discontinuity developed along its length can be easily detected. When the sensor is placed in immediate vicinity to the steel reinforcement it is subjected to the same chemical process as the steel reinforcement. And corrosion pitting is expected to develop on the sensor exactly at the same location as in the rebar. Thus it is expected to be an effective tool for active corrosion zones detection within reinforced concrete (RC) members. A series of laboratory tests were conducted to validate the effectiveness of the proposed methodology. Nine sensors were manufactured and placed in the artificially created corrosive environment and observed over the time. To induce accelerated corrosion 3% and 5% NaCL solutions were used. Based on the test results, the proposed/corrosion distributed sensor is capable of delivering fairly accurate information on the location of a discontinuity along the sensor caused by corrosion pitting. Forensic study was also conducted to validate the concept. In order to test the sensors in real live condition, 27 sensors were prepared to be placed into RC beams. The beams will be subjected to corrosive environment. After that the sensors will be monitored over the time for signs of corrosion.

Invited review: sensors to support health management on dairy farms.

PubMed

Rutten, C J; Velthuis, A G J; Steeneveld, W; Hogeveen, H

2013-04-01

Since the 1980s, efforts have been made to develop sensors that measure a parameter from an individual cow. The development started with individual cow recognition and was followed by sensors that measure the electrical conductivity of milk and pedometers that measure activity. The aim of this review is to provide a structured overview of the published sensor systems for dairy health management. The development of sensor systems can be described by the following 4 levels: (I) techniques that measure something about the cow (e.g., activity); (II) interpretations that summarize changes in the sensor data (e.g., increase in activity) to produce information about the cow's status (e.g., estrus); (III) integration of information where sensor information is supplemented with other information (e.g., economic information) to produce advice (e.g., whether to inseminate a cow or not); and (IV) the farmer makes a decision or the sensor system makes the decision autonomously (e.g., the inseminator is called). This review has structured a total of 126 publications describing 139 sensor systems and compared them based on the 4 levels. The publications were published in the Thomson Reuters (formerly ISI) Web of Science database from January 2002 until June 2012 or in the proceedings of 3 conferences on precision (dairy) farming in 2009, 2010, and 2011. Most studies concerned the detection of mastitis (25%), fertility (33%), and locomotion problems (30%), with fewer studies (16%) related to the detection of metabolic problems. Many studies presented sensor systems at levels I and II, but none did so at levels III and IV. Most of the work for mastitis (92%) and fertility (75%) is done at level II. For locomotion (53%) and metabolism (69%), more than half of the work is done at level I. The performance of sensor systems varies based on the choice of gold standards, algorithms, and test sizes (number of farms and cows). Studies on sensor systems for mastitis and estrus have shown that sensor systems are brought to a higher level; however, the need to improve detection performance still exists. Studies on sensor systems for locomotion problems have shown that the search continues for the most appropriate indicators, sensor techniques, and gold standards. Studies on metabolic problems show that it is still unclear which indicator reflects best the metabolic problems that should be detected. No systems with integrated decision support models have been found. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Investigation of the applicability of using the triple redundant hydrogen sensor for methane sensing

NASA Technical Reports Server (NTRS)

Lantz, J. B.; Wynveen, R. A.

1983-01-01

Application specifications for the methane sensor were assembled and design guidelines, development goals and evaluation criteria were formulated. This was done to provide a framework to evaluate sensor performance and any design adjustments to the preprototype sensor that could be required to provide methane sensitivity. Good response to hydrogen was experimentally established for four hydrogen sensor elements to be later evaluated for methane response. Prior results were assembled and analyzed for other prototype hydrogen sensor performance parameters to form a comparison base. The four sensor elements previously shown to have good hydrogen response were experimentally evaluated for methane response in 2.5% methane-in-air. No response was obtained for any of the elements, despite the high methane concentration used (50% of the Lower Flammability Limit). It was concluded that the preprototype sensing elements were insensitive to methane and were hydrogen specific. Alternative sensor operating conditions and hardware design changes were considered to provide methane sensitivity to the preprototype sensor, including a variety of different methane sensing techniques. Minor changes to the existing sensor elements, sensor geometry and operating conditions will not make the preprototype hydrogen sensor respond to methane. New sensor elements that will provide methane and hydrogen sensitivity require replacement of the existing thermistor type elements. Some hydrogen sensing characteristics of the modified sensor will be compromised (larger in situ calibration gas volume and H2 nonspecificity). The preprototype hydrogen sensor should be retained for hydrogen monitoring and a separate methane sensor should be developed.

MASM: a market architecture for sensor management in distributed sensor networks

NASA Astrophysics Data System (ADS)

Viswanath, Avasarala; Mullen, Tracy; Hall, David; Garga, Amulya

2005-03-01

Rapid developments in sensor technology and its applications have energized research efforts towards devising a firm theoretical foundation for sensor management. Ubiquitous sensing, wide bandwidth communications and distributed processing provide both opportunities and challenges for sensor and process control and optimization. Traditional optimization techniques do not have the ability to simultaneously consider the wildly non-commensurate measures involved in sensor management in a single optimization routine. Market-oriented programming provides a valuable and principled paradigm to designing systems to solve this dynamic and distributed resource allocation problem. We have modeled the sensor management scenario as a competitive market, wherein the sensor manager holds a combinatorial auction to sell the various items produced by the sensors and the communication channels. However, standard auction mechanisms have been found not to be directly applicable to the sensor management domain. For this purpose, we have developed a specialized market architecture MASM (Market architecture for Sensor Management). In MASM, the mission manager is responsible for deciding task allocations to the consumers and their corresponding budgets and the sensor manager is responsible for resource allocation to the various consumers. In addition to having a modified combinatorial winner determination algorithm, MASM has specialized sensor network modules that address commensurability issues between consumers and producers in the sensor network domain. A preliminary multi-sensor, multi-target simulation environment has been implemented to test the performance of the proposed system. MASM outperformed the information theoretic sensor manager in meeting the mission objectives in the simulation experiments.

Passive Sensors for Long Duration Internet of Things Networks.

PubMed

Pereira, Felisberto; Correia, Ricardo; Carvalho, Nuno Borges

2017-10-03

In this work, three different concepts are used to develop a fully passive sensor that is capable of measuring different types of data. The sensor was supplied by Wireless Power Transmission (WPT). Communication between the sensor and reader is established by a backscatter, and to ensure minimum energy consumption, low power techniques are used. In a simplistic way, the process starts by the transmission of two different waves by the reader to the sensor, one of which is used in power transmission and the other of which is used to communicate. Once the sensor is powered, the monitoring process starts. From the monitoring state, results from after processing are used to modulate the incoming wave, which is the information that is sent back from the reader to the tag. This new combination of technologies enables the possibility of using sensors without any cables or batteries to operate 340 cm from the reader. The developed prototype measures acceleration and temperature. However, it is scalable. This system enables a new generation of passive Internet of Things (IoT) devices.

Passive Sensors for Long Duration Internet of Things Networks

PubMed Central

Correia, Ricardo; Carvalho, Nuno Borges

2017-01-01

In this work, three different concepts are used to develop a fully passive sensor that is capable of measuring different types of data. The sensor was supplied by Wireless Power Transmission (WPT). Communication between the sensor and reader is established by a backscatter, and to ensure minimum energy consumption, low power techniques are used. In a simplistic way, the process starts by the transmission of two different waves by the reader to the sensor, one of which is used in power transmission and the other of which is used to communicate. Once the sensor is powered, the monitoring process starts. From the monitoring state, results from after processing are used to modulate the incoming wave, which is the information that is sent back from the reader to the tag. This new combination of technologies enables the possibility of using sensors without any cables or batteries to operate 340 cm from the reader. The developed prototype measures acceleration and temperature. However, it is scalable. This system enables a new generation of passive Internet of Things (IoT) devices. PMID:28972554

A Low Power 2.4 GHz CMOS Mixer Using Forward Body Bias Technique for Wireless Sensor Network

NASA Astrophysics Data System (ADS)

Yin, C. J.; Murad, S. A. Z.; Harun, A.; Ramli, M. M.; Zulkifli, T. Z. A.; Karim, J.

2018-03-01

Wireless sensor network (WSN) is a highly-demanded application since the evolution of wireless generation which is often used in recent communication technology. A radio frequency (RF) transceiver in WSN should have a low power consumption to support long operating times of mobile devices. A down-conversion mixer is responsible for frequency translation in a receiver. By operating a down-conversion mixer at a low supply voltage, the power consumed by WSN receiver can be greatly reduced. This paper presents a development of low power CMOS mixer using forward body bias technique for wireless sensor network. The proposed mixer is implemented using CMOS 0.13 μm Silterra technology. The forward body bias technique is adopted to obtain low power consumption. The simulation results indicate that a low power consumption of 0.91 mW is achieved at 1.6 V supply voltage. Moreover, the conversion gain (CG) of 21.83 dB, the noise figure (NF) of 16.51 dB and the input-referred third-order intercept point (IIP3) of 8.0 dB at 2.4 GHz are obtained. The proposed mixer is suitable for wireless sensor network.

Surface Modification Enhanced Reflection Intensity of Quartz Crystal Microbalance Sensors upon Molecular Adsorption.

PubMed

Kojima, Taisuke

2018-01-01

Molecular adsorption on a sensing surface involves molecule-substrate and molecule-molecule interactions. Combining optical systems and a quartz crystal microbalance (QCM) on the same sensing surface allows the quantification of such interactions and reveals the physicochemical properties of the adsorbed molecules. However, low sensitivity of the current reflection-based techniques compared to the QCM technique hinders the quantitative analysis of the adsorption events. Here, a layer-by-layer surface modification of a QCM sensor is studied to increase the optical sensitivity. The intermediate layers of organic-inorganic molecules and metal-metal oxide were explored on a gold (Au) surface of a QCM sensor. First, polyhedral oligomeric silsesquioxane-derivatives that served as the organic-inorganic intermediate layer were synthesized and modified on the Au-QCM surface. Meanwhile, titanium oxide, fabricated by anodic oxidation of titanium, was used as a metal-metal oxide intermediate layer on a titanium-coated QCM surface. The developed technique enabled interrogation of the molecular adsorption owing to the enhanced optical sensitivity.

Magnetic moment investigation by frequency mixing techniques.

PubMed

Teliban, I; Thede, C; Chemnitz, S; Bechtold, C; Quadakkers, W J; Schütze, M; Quandt, E

2009-11-01

Gas turbines and other large industrial equipment are subjected to high-temperature oxidation and corrosion. Research and development of efficient protective coatings is the main task in the field. Also, knowledge about the depletion state of the coating during the operation time is important. To date, practical nondestructive methods for the measurement of the depletion state do not exist. By integrating magnetic phases into the coating, the condition of the coating can be determined by measuring its magnetic properties. In this paper, a new technique using frequency mixing is proposed to investigate the thickness of the coatings based on their magnetic properties. A sensor system is designed and tested on specific magnetic coatings. New approaches are proposed to overcome the dependency of the measurement on the distance between coil and sample that all noncontact techniques face. The novelty is a low cost sensor with high sensibility and selectivity which can provide very high signal-to-noise ratios. Prospects and limitations are discussed for future use of the sensor in industrial applications.

Applications of Kalman filtering to real-time trace gas concentration measurements

NASA Technical Reports Server (NTRS)

Leleux, D. P.; Claps, R.; Chen, W.; Tittel, F. K.; Harman, T. L.

2002-01-01

A Kalman filtering technique is applied to the simultaneous detection of NH3 and CO2 with a diode-laser-based sensor operating at 1.53 micrometers. This technique is developed for improving the sensitivity and precision of trace gas concentration levels based on direct overtone laser absorption spectroscopy in the presence of various sensor noise sources. Filter performance is demonstrated to be adaptive to real-time noise and data statistics. Additionally, filter operation is successfully performed with dynamic ranges differing by three orders of magnitude. Details of Kalman filter theory applied to the acquired spectroscopic data are discussed. The effectiveness of this technique is evaluated by performing NH3 and CO2 concentration measurements and utilizing it to monitor varying ammonia and carbon dioxide levels in a bioreactor for water reprocessing, located at the NASA-Johnson Space Center. Results indicate a sensitivity enhancement of six times, in terms of improved minimum detectable absorption by the gas sensor.

3D printed stretchable capacitive sensors for highly sensitive tactile and electrochemical sensing

NASA Astrophysics Data System (ADS)

Li, Kai; Wei, Hong; Liu, Wenguang; Meng, Hong; Zhang, Peixin; Yan, Chaoyi

2018-05-01

Developments of innovative strategies for the fabrication of stretchable sensors are of crucial importance for their applications in wearable electronic systems. In this work, we report the successful fabrication of stretchable capacitive sensors using a novel 3D printing method for highly sensitive tactile and electrochemical sensing applications. Unlike conventional lithographic or templated methods, the programmable 3D printing technique can fabricate complex device structures in a cost-effective and facile manner. We designed and fabricated stretchable capacitive sensors with interdigital and double-vortex designs and demonstrated their successful applications as tactile and electrochemical sensors. Especially, our stretchable sensors exhibited a detection limit as low as 1 × 10-6 M for NaCl aqueous solution, which could have significant potential applications when integrated in electronics skins.

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

3D printed stretchable capacitive sensors for highly sensitive tactile and electrochemical sensing.

PubMed

Li, Kai; Wei, Hong; Liu, Wenguang; Meng, Hong; Zhang, Peixin; Yan, Chaoyi

2018-05-04

Developments of innovative strategies for the fabrication of stretchable sensors are of crucial importance for their applications in wearable electronic systems. In this work, we report the successful fabrication of stretchable capacitive sensors using a novel 3D printing method for highly sensitive tactile and electrochemical sensing applications. Unlike conventional lithographic or templated methods, the programmable 3D printing technique can fabricate complex device structures in a cost-effective and facile manner. We designed and fabricated stretchable capacitive sensors with interdigital and double-vortex designs and demonstrated their successful applications as tactile and electrochemical sensors. Especially, our stretchable sensors exhibited a detection limit as low as 1 × 10 -6 M for NaCl aqueous solution, which could have significant potential applications when integrated in electronics skins.

Multiplexing Technology for Acoustic Emission Monitoring of Aerospace Vehicles

NASA Technical Reports Server (NTRS)

Prosser, William; Percy, Daniel

2003-01-01

The initiation and propagation of damage mechanisms such as cracks and delaminations generate acoustic waves, which propagate through a structure. These waves can be detected and analyzed to provide the location and severity of damage as part of a structural health monitoring (SHM) system. This methodology of damage detection is commonly known as acoustic emission (AE) monitoring, and is widely used on a variety of applications on civil structures. AE has been widely considered for SHM of aerospace vehicles. Numerous successful ground and flight test demonstrations have been performed, which show the viability of the technology for damage monitoring in aerospace structures. However, one significant current limitation for application of AE techniques on aerospace vehicles is the large size, mass, and power requirements for the necessary monitoring instrumentation. To address this issue, a prototype multiplexing approach has been developed and demonstrated in this study, which reduces the amount of AE monitoring instrumentation required. Typical time division multiplexing techniques that are commonly used to monitor strain, pressure and temperature sensors are not applicable to AE monitoring because of the asynchronous and widely varying rates of AE signal occurrence. Thus, an event based multiplexing technique was developed. In the initial prototype circuit, inputs from eight sensors in a linear array were multiplexed into two data acquisition channels. The multiplexer rapidly switches, in less than one microsecond, allowing the signals from two sensors to be acquired by a digitizer. The two acquired signals are from the sensors on either side of the trigger sensor. This enables the capture of the first arrival of the waves, which cannot be accomplished with the signal from the trigger sensor. The propagation delay to the slightly more distant neighboring sensors makes this possible. The arrival time from this first arrival provides a more accurate source location determination. The multiplexer also identifies which channels are acquired by encoding TTL logic pulses onto the latter portion of the signals. This prototype system was demonstrated using pencil lead break (Hsu-Neilsen) sources on an aluminum plate. It performed as designed providing rapid low noise trigger based switching with encoded channel identification. this multiplexing approach is not limited to linear arrays, but can be easily extended to monitor sensors in planar ot three dimensional arrays. A 32 channel multiplexing system is under development that will allow arbitrary sensor placement. Another benefit of this multiplexing system is the reduction in the expense of data acquisition hardware. In addition, the reduced weight and power requirements are of extreme importance for proposed AE systems on aerospace vehicles.

Future Technology-Driven Revolutions in Military Operations. Results of a Workshop

DTIC Science & Technology

1994-01-01

sensor missions. "• Biomolecular Electronics - The use of techniques from molecular biology and biotechnology to develop new molecular electronic materials...34* Biomolecular electronics - The use of techniques from molecular biology and biotechnology to develop new molecular electronic materials, components, and...occurring in molecular biology . 42 Biotechnology Molecular Biologists Arm Develoni "Magical" Caoabilitles "• To mynthsieh genm (frm satch) with conboi

Loss-compensation technique using a split-spectrum approach for optical fiber air-gap intensity-based sensors

NASA Astrophysics Data System (ADS)

Wang, Anbo; Miller, Mark S.; Gunther, Michael F.; Murphy, Kent A.; Claus, Richard O.

1993-03-01

A self-referencing technique compensating for fiber losses and source fluctuations in air-gap intensity-based optical fiber sensors is described and demonstrated. A resolution of 0.007 micron has been obtained over a measurement range of 0-250 microns for an intensity-based displacement sensor using this referencing technique. The sensor is shown to have minimal sensitivity to fiber bending losses and variations in the LED input power. A theoretical model for evaluation of step-index multimode optical fiber splice is proposed. The performance of the sensor as a displacement sensor agrees well with the theoretical analysis.

Basement Membrane-Based Glucose Sensor Coatings Enhance Continuous Glucose Monitoring in Vivo

PubMed Central

Klueh, Ulrike; Qiao, Yi; Czajkowski, Caroline; Ludzinska, Izabela; Antar, Omar; Kreutzer, Donald L.

2015-01-01

Background: Implantable glucose sensors demonstrate a rapid decline in function that is likely due to biofouling of the sensor. Previous efforts directed at overcoming this issue has generally focused on the use of synthetic polymer coatings, with little apparent effect in vivo, clearly a novel approach is required. We believe that the key to extending sensor life span in vivo is the development of biocompatible basement membrane (BM) based bio-hydrogels as coatings for glucose sensors. Method: BM based bio-hydrogel sensor coatings were developed using purified BM preparations (ie, Cultrex from Trevigen Inc). Modified Abbott sensors were coated with Cultrex BM extracts. Sensor performance was evaluated for the impact of these coatings in vitro and in vivo in a continuous glucose monitoring (CGM) mouse model. In vivo sensor function was assessed over a 28-day time period expressed as mean absolute relative difference (MARD) values. Tissue reactivity of both Cultrex coated and uncoated glucose sensors was evaluated at 7, 14, 21 and 28 days post–sensor implantation with standard histological techniques. Results: The data demonstrate that Cultrex-based sensor coatings had no effect on glucose sensor function in vitro. In vivo glucose sensor performance was enhanced following BM coating as determined by MARD analysis, particularly in weeks 2 and 3. In vivo studies also demonstrated that Cultrex coatings significantly decreased sensor-induced tissue reactions at the sensor implantation sites. Conclusion: Basement-membrane-based sensor coatings enhance glucose sensor function in vivo, by minimizing or preventing sensor-induced tissues reactions. PMID:26306494

A proteorhodopsin-based biohybrid light-powering pH sensor.

PubMed

Rao, Siyuan; Guo, Zhibin; Liang, Dawei; Chen, Deliang; Wei, Yen; Xiang, Yan

2013-10-14

The biohybrid sensor is an emerging technique for multi-functional detection that utilizes the instinctive responses or interactions of biomolecules. We develop a biohybrid pH sensor by taking advantage of the pH-dependent photoelectric characteristics of proteorhodopsin (pR). The transient absorption kinetics study indicates that the photoelectric behavior of pR is attributed to the varying lifetime of the M intermediate at different environmental pH values. This pR-based biohybrid light-powering sensor with microfluidic design can achieve real-time pH detection with quick response and high sensitivity. The results of this work would shed light on pR and its potential applications.

Plastic optical fibre sensor for quality control in food industry

NASA Astrophysics Data System (ADS)

Novo, C.; Bilro, L.; Ferreira, R.; Alberto, N.; Antunes, P.; Leitão, C.; Nogueira, R.; Pinto, J. L.

2013-05-01

The present work addresses the need for new devices felt in the context of quality control, especially in the food industry. Due to the spectral dependence of the attenuation coefficient, a novel dual-parameter sensor for colour and refractive index was developed and tested. The sensor employs plastic optical fibres to measure the transmitted optical power in three measurement cells each with a different incident wavelength. The performance of the sensor was tested using several dyes at different concentrations and aqueous solutions of glycerine and ethanol. Results show that this technique allows the monitoring of refractive index and colour without cross-sensitivity.

Design and synthesis of a fluorescent molecular imprinted polymer for use in an optical fibre-based cocaine sensor

NASA Astrophysics Data System (ADS)

Wren, Stephen P.; Piletsky, Sergey A.; Karim, Kal; Gascoine, Paul; Lacey, Richard; Sun, Tong; Grattan, Kenneth T. V.

2014-05-01

Previously, we have developed chemical sensors using fibre optic-based techniques for the detection of Cocaine, utilising molecularly imprinted polymers (MIPs) containing fluorescein moieties as the signalling groups. Here, we report the computational design of a fluorophore which was incorporated into a MIP for the generation of a novel sensor that offers improved sensitivity for Cocaine with a detection range of 1-100μM. High selectivity for Cocaine over a suite of known Cocaine interferants (25μM) was also demonstrated by measuring changes in the intensity of fluorescence signals received from the sensor.

A Novel Wearable Sensor-Based Human Activity Recognition Approach Using Artificial Hydrocarbon Networks.

PubMed

Ponce, Hiram; Martínez-Villaseñor, María de Lourdes; Miralles-Pechuán, Luis

2016-07-05

Human activity recognition has gained more interest in several research communities given that understanding user activities and behavior helps to deliver proactive and personalized services. There are many examples of health systems improved by human activity recognition. Nevertheless, the human activity recognition classification process is not an easy task. Different types of noise in wearable sensors data frequently hamper the human activity recognition classification process. In order to develop a successful activity recognition system, it is necessary to use stable and robust machine learning techniques capable of dealing with noisy data. In this paper, we presented the artificial hydrocarbon networks (AHN) technique to the human activity recognition community. Our artificial hydrocarbon networks novel approach is suitable for physical activity recognition, noise tolerance of corrupted data sensors and robust in terms of different issues on data sensors. We proved that the AHN classifier is very competitive for physical activity recognition and is very robust in comparison with other well-known machine learning methods.

Phase Contrast Wavefront Sensing for Adaptive Optics

NASA Technical Reports Server (NTRS)

Bloemhof, E. E.; Wallace, J. K.; Bloemhof, E. E.

2004-01-01

Most ground-based adaptive optics systems use one of a small number of wavefront sensor technologies, notably (for relatively high-order systems) the Shack-Hartmann sensor, which provides local measurements of the phase slope (first-derivative) at a number of regularly-spaced points across the telescope pupil. The curvature sensor, with response proportional to the second derivative of the phase, is also sometimes used, but has undesirable noise propagation properties during wavefront reconstruction as the number of actuators becomes large. It is interesting to consider the use for astronomical adaptive optics of the "phase contrast" technique, originally developed for microscopy by Zemike to allow convenient viewing of phase objects. In this technique, the wavefront sensor provides a direct measurement of the local value of phase in each sub-aperture of the pupil. This approach has some obvious disadvantages compared to Shack-Hartmann wavefront sensing, but has some less obvious but substantial advantages as well. Here we evaluate the relative merits in a practical ground-based adaptive optics system.

Analyzing Single Giant Unilamellar Vesicles With a Slotline-Based RF Nanometer Sensor

DOE PAGES

Cui, Yan; Kenworthy, Anne K.; Edidin, Michael; ...

2016-03-11

Novel techniques that enable reagent free detection and analysis of single cells are of great interest for the development of biological and medical sciences, as well as point-of-care health service technologies. Highly sensitive and broadband RF sensors are promising candidates for such a technique. In this paper, we present a highly sensitive and tunable RF sensor, which is based on interference processes and built with a 100-nm slotline structure. The highly concentrated RF fields, up to ~ 1.76×10 7 V/m, enable strong interactions between giant unilamellar vesicles (GUVs) and fields for high-sensitivity operations. We also provide two modeling approaches tomore » extract cell dielectric properties from measured scattering parameters. GUVs of different molecular compositions are synthesized and analyzed with the RF sensor at ~ 2, ~ 2.5, and ~ 2.8 GHz with an initial |S 21| min of ~ -100 dB. Corresponding GUV dielectric properties are obtained. Finally, a one-dimensional scanning of single GUV is also demonstrated.« less

Demonstration of automated proximity and docking technologies

NASA Astrophysics Data System (ADS)

Anderson, Robert L.; Tsugawa, Roy K.; Bryan, Thomas C.

An autodock was demonstrated using straightforward techniques and real sensor hardware. A simulation testbed was established and validated. The sensor design was refined with improved optical performance and image processing noise mitigation techniques, and the sensor is ready for production from off-the-shelf components. The autonomous spacecraft architecture is defined. The areas of sensors, docking hardware, propulsion, and avionics are included in the design. The Guidance Navigation and Control architecture and requirements are developed. Modular structures suitable for automated control are used. The spacecraft system manager functions including configuration, resource, and redundancy management are defined. The requirements for autonomous spacecraft executive are defined. High level decisionmaking, mission planning, and mission contingency recovery are a part of this. The next step is to do flight demonstrations. After the presentation the following question was asked. How do you define validation? There are two components to validation definition: software simulation with formal and vigorous validation, and hardware and facility performance validated with respect to software already validated against analytical profile.

Spatially distributed modal signals of free shallow membrane shell structronic system

NASA Astrophysics Data System (ADS)

Yue, H. H.; Deng, Z. Q.; Tzou, H. S.

2008-11-01

Based on the smart material and structronics technology, distributed sensor and control of shell structures have been rapidly developed for the last 20 years. This emerging technology has been utilized in aerospace, telecommunication, micro-electromechanical systems and other engineering applications. However, distributed monitoring technique and its resulting global spatially distributed sensing signals of shallow paraboloidal membrane shells are not clearly understood. In this paper, modeling of free flexible paraboloidal shell with spatially distributed sensor, micro-sensing signal characteristics, and location of distributed piezoelectric sensor patches are investigated based on a new set of assumed mode shape functions. Parametric analysis indicates that the signal generation depends on modal membrane strains in the meridional and circumferential directions in which the latter is more significant than the former, when all bending strains vanish in membrane shells. This study provides a modeling and analysis technique for distributed sensors laminated on lightweight paraboloidal flexible structures and identifies critical components and regions that generate significant signals.

Spatial Signal Characteristics of Shallow Paraboloidal Shell Structronic Systems

NASA Astrophysics Data System (ADS)

Yue, H. H.; Deng, Z. Q.; Tzou, H. S.

Based on the smart material and structronics technology, distributed sensor and control of shell structures have been rapidly developed for the last twenty years. This emerging technology has been utilized in aerospace, telecommunication, micro-electromechanical systems and other engineering applications. However, distributed monitoring technique and its resulting global spatially distributed sensing signals of thin flexible membrane shells are not clearly understood. In this paper, modeling of free thin paraboloidal shell with spatially distributed sensor, micro-sensing signal characteristics, and location of distributed piezoelectric sensor patches are investigated based on a new set of assumed mode shape functions. Parametric analysis indicates that the signal generation depends on modal membrane strains in the meridional and circumferential directions in which the latter is more significant than the former, when all bending strains vanish in membrane shells. This study provides a modeling and analysis technique for distributed sensors laminated on lightweight paraboloidal flexible structures and identifies critical components and regions that generate significant signals.

Smart fabric sensors and e-textile technologies: a review

NASA Astrophysics Data System (ADS)

Castano, Lina M.; Flatau, Alison B.

2014-05-01

This paper provides a review of recent developments in the rapidly changing and advancing field of smart fabric sensor and electronic textile technologies. It summarizes the basic principles and approaches employed when building fabric sensors as well as the most commonly used materials and techniques used in electronic textiles. This paper shows that sensing functionality can be created by intrinsic and extrinsic modifications to textile substrates depending on the level of integration into the fabric platform. The current work demonstrates that fabric sensors can be tailored to measure force, pressure, chemicals, humidity and temperature variations. Materials, connectors, fabric circuits, interconnects, encapsulation and fabrication methods associated with fabric technologies prove to be customizable and versatile but less robust than their conventional electronics counterparts. The findings of this survey suggest that a complete smart fabric system is possible through the integration of the different types of textile based functional elements. This work intends to be a starting point for standardization of smart fabric sensing techniques and e-textile fabrication methods.

Commercial Capaciflector

NASA Technical Reports Server (NTRS)

Vranish, John M.

1991-01-01

A capacitive proximity/tactile sensor with unique performance capabilities ('capaciflector' or capacitive reflector) is being developed by NASA/Goddard Space Flight Center (GSFC) for use on robots and payloads in space in the interests of safety, efficiency, and ease of operation. Specifically, this sensor will permit robots and their attached payloads to avoid collisions in space with humans and other objects and to dock these payloads in a cluttered environment. The sensor is simple, robust, and inexpensive to manufacture with obvious and recognized commercial possibilities. Accordingly, NASA/GSFC, in conjunction with industry, is embarking on an effort to 'spin' this technology off into the private sector. This effort includes prototypes aimed at commercial applications. The principles of operation of these prototypes are described along with hardware, software, modelling, and test results. The hardware description includes both the physical sensor in terms of a flexible printed circuit board and the electronic circuitry. The software description will include filtering and detection techniques. The modelling will involve finite element electric field analysis and will underline techniques used for design optimization.

Color regeneration from reflective color sensor using an artificial intelligent technique.

PubMed

Saracoglu, Ömer Galip; Altural, Hayriye

2010-01-01

A low-cost optical sensor based on reflective color sensing is presented. Artificial neural network models are used to improve the color regeneration from the sensor signals. Analog voltages of the sensor are successfully converted to RGB colors. The artificial intelligent models presented in this work enable color regeneration from analog outputs of the color sensor. Besides, inverse modeling supported by an intelligent technique enables the sensor probe for use of a colorimetric sensor that relates color changes to analog voltages.

Integrated control and health monitoring capacitive displacement sensor development task. Orbit transfer rocket engine technology program

NASA Technical Reports Server (NTRS)

Collamore, Frank N.

1989-01-01

The development of a miniature multifunction turbomachinery shaft displacement sensor using state-of-the-art non-contract capacitive sensing technology is described. Axial displacement, radial displacement, and speed are sensed using a single probe within the envelope normally required for a single function. A survey of displacement sensing technology is summarized including inductive, capacitive, optical and ultrasonic techniques. The design and operation of an experimental triple function sensor is described. Test results are included showing calibration tests and simultaneous dynamic testing of multiple functions. Recommendations for design changes are made to improve low temperature performance, reliability, and for design of a flight type signal conditioning unit.

Sensory grammars for sensor networks

PubMed Central

Aloimonos, Yiannis

2009-01-01

One of the major goals of Ambient Intelligence and Smart Environments is to interpret human activity sensed by a variety of sensors. In order to develop useful technologies and a subsequent industry around smart environments, we need to proceed in a principled manner. This paper suggests that human activity can be expressed in a language. This is a special language with its own phonemes, its own morphemes (words) and its own syntax and it can be learned using machine learning techniques applied to gargantuan amounts of data collected by sensor networks. Developing such languages will create bridges between Ambient Intelligence and other disciplines. It will also provide a hierarchical structure that can lead to a successful industry. PMID:21897837

Method for fabrication and verification of conjugated nanoparticle-antibody tuning elements for multiplexed electrochemical biosensors.

PubMed

La Belle, Jeffrey T; Fairchild, Aaron; Demirok, Ugur K; Verma, Aman

2013-05-15

There is a critical need for more accurate, highly sensitive and specific assay for disease diagnosis and management. A novel, multiplexed, single sensor using rapid and label free electrochemical impedance spectroscopy tuning method has been developed. The key challenges while monitoring multiple targets is frequency overlap. Here we describe the methods to circumvent the overlap, tune by use of nanoparticle (NP) and discuss the various fabrication and characterization methods to develop this technique. First sensors were fabricated using printed circuit board (PCB) technology and nickel and gold layers were electrodeposited onto the PCB sensors. An off-chip conjugation of gold NP's to molecular recognition elements (with verification technique) is described as well. A standard covalent immobilization of the molecular recognition elements is also discussed with quality control techniques. Finally use and verification of sensitivity and specificity is also presented. By use of gold NP's of various sizes, we have demonstrated the possibility and shown little loss of sensitivity and specificity in the molecular recognition of inflammatory markers as "model" targets for our tuning system. By selection of other sized NP's or NP's of various materials, the tuning effect can be further exploited. The novel platform technology developed could be utilized in critical care, clinical management and at home health and disease management. Copyright © 2013 Elsevier Inc. All rights reserved.

An air flow sensor for neonatal mechanical ventilation applications based on a novel fiber-optic sensing technique

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

Battista, L.; Sciuto, S. A.; Scorza, A.

2013-03-15

In this work, a simple and low-cost air flow sensor, based on a novel fiber-optic sensing technique has been developed for monitoring air flows rates supplied by a neonatal ventilator to support infants in intensive care units. The device is based on a fiber optic sensing technique allowing (a) the immunity to light intensity variations independent by measurand and (b) the reduction of typical shortcomings affecting all biomedical fields (electromagnetic interference and patient electrical safety). The sensing principle is based on the measurement of transversal displacement of an emitting fiber-optic cantilever due to action of air flow acting on it;more » the fiber tip displacement is measured by means of a photodiode linear array, placed in front of the entrance face of the emitting optical fiber in order to detect its light intensity profile. As the measurement system is based on a detection of the illumination pattern, and not on an intensity modulation technique, it results less sensitive to light intensity fluctuation independent by measurand than intensity-based sensors. The considered technique is here adopted in order to develop two different configurations for an air flow sensor suitable for the measurement of air flow rates typically occurring during mechanical ventilation of newborns: a mono-directional and a bi-directional transducer have been proposed. A mathematical model for the air flow sensor is here proposed and a static calibration of two different arrangements has been performed: a measurement range up to 3.00 Multiplication-Sign 10{sup -4} m{sup 3}/s (18.0 l/min) for the mono-directional sensor and a measurement range of {+-}3.00 Multiplication-Sign 10{sup -4} m{sup 3}/s ({+-}18.0 l/min) for the bi-directional sensor are experimentally evaluated, according to the air flow rates normally encountered during tidal breathing of infants with a mass lower than 10 kg. Experimental data of static calibration result in accordance with the proposed theoretical model: for the mono-directional configuration, the coefficient of determination r{sup 2} is equal to 0.997; for the bi-directional configuration, the coefficient of determination r{sup 2} is equal to 0.990 for positive flows (inspiration) and 0.988 for negative flows (expiration). Measurement uncertainty {delta}Q of air flow rate has been evaluated by means of the propagation of distributions and the percentage error in the arrangement of bi-directional sensor ranges from a minimum of about 0.5% at -18.0 l/min to a maximum of about 9% at -12.0 l/min.« less

Thermal Flow Sensors for Harsh Environments.

PubMed

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

2017-09-08

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

Thermal Flow Sensors for Harsh Environments

PubMed Central

Dinh, Toan; Dao, Dzung Viet

2017-01-01

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

A sensitive, handheld vapor sensor based on microcantilevers

NASA Astrophysics Data System (ADS)

Pinnaduwage, L. A.; Hedden, D. L.; Gehl, A.; Boiadjiev, V. I.; Hawk, J. E.; Farahi, R. H.; Thundat, T.; Houser, E. J.; Stepnowski, S.; McGill, R. A.; Deel, L.; Lareau, R. T.

2004-11-01

We report the development of a handheld sensor based on piezoresistive microcantilevers that does not depend on optical detection, yet has high detection sensitivity. The sensor is able to detect vapors from the plastic explosives pentaerythritol tetranitrate and hexahydro-1,3,5-triazine at levels below 10 parts per trillion within few seconds of exposure under ambient conditions. A differential measurement technique has yielded a rugged sensor that is unaffected by vibration and is able to function as a "sniffer." The microelectromechanical system sensor design allows for the incorporation of hundreds of microcantilevers with suitable coatings in order to achieve sufficient selectivity in the future, and thus could provide an inexpensive, unique platform for the detection of chemical, biological, and explosive materials.

Smart catheter flow sensor for real-time continuous regional cerebral blood flow monitoring

NASA Astrophysics Data System (ADS)

Li, Chunyan; Wu, Pei-Ming; Hartings, Jed A.; Wu, Zhizhen; Ahn, Chong H.; LeDoux, David; Shutter, Lori A.; Narayan, Raj K.

2011-12-01

We present a smart catheter flow sensor for real-time, continuous, and quantitative measurement of regional cerebral blood flow using in situ temperature and thermal conductivity compensation. The flow sensor operates in a constant-temperature mode and employs a periodic heating and cooling technique. This approach ensures zero drift and provides highly reliable data with microelectromechanical system-based thin film sensors. The developed flow sensor has a sensitivity of 0.973 mV/ml/100 g/min in the range from 0 to 160 ml/100 g/min with a linear correlation coefficient of R2 = 0.9953. It achieves a resolution of 0.25 ml/100 g/min and an accuracy better than 5 ml/100 g/min.

Sensor fusion III: 3-D perception and recognition; Proceedings of the Meeting, Boston, MA, Nov. 5-8, 1990

NASA Technical Reports Server (NTRS)

Schenker, Paul S. (Editor)

1991-01-01

The volume on data fusion from multiple sources discusses fusing multiple views, temporal analysis and 3D motion interpretation, sensor fusion and eye-to-hand coordination, and integration in human shape perception. Attention is given to surface reconstruction, statistical methods in sensor fusion, fusing sensor data with environmental knowledge, computational models for sensor fusion, and evaluation and selection of sensor fusion techniques. Topics addressed include the structure of a scene from two and three projections, optical flow techniques for moving target detection, tactical sensor-based exploration in a robotic environment, and the fusion of human and machine skills for remote robotic operations. Also discussed are K-nearest-neighbor concepts for sensor fusion, surface reconstruction with discontinuities, a sensor-knowledge-command fusion paradigm for man-machine systems, coordinating sensing and local navigation, and terrain map matching using multisensing techniques for applications to autonomous vehicle navigation.

The application of remote sensing techniques: Technical and methodological issues

NASA Technical Reports Server (NTRS)

Polcyn, F. C.; Wagner, T. W.

1974-01-01

Capabilities and limitations of modern imaging electromagnetic sensor systems are outlined, and the products of such systems are compared with those of the traditional aerial photographic system. Focus is given to the interface between the rapidly developing remote sensing technology and the information needs of operational agencies, and communication gaps are shown to retard early adoption of the technology by these agencies. An assessment is made of the current status of imaging remote sensors and their potential for the future. Public sources of remote sensor data and several cost comparisons are included.

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.

Germanium Lift-Off Masks for Thin Metal Film Patterning

NASA Technical Reports Server (NTRS)

Brown, Ari

2012-01-01

A technique has been developed for patterning thin metallic films that are, in turn, used to fabricate microelectronics circuitry and thin-film sensors. The technique uses germanium thin films as lift-off masks. This requires development of a technique to strip or undercut the germanium chemically without affecting the deposited metal. Unlike in the case of conventional polymeric lift-off masks, the substrate can be exposed to very high temperatures during processing (sputter deposition). The reason why polymeric liftoff masks cannot be exposed to very high temperatures (greater than 100 C) is because (a) they can become cross linked, making lift-off very difficult if not impossible, and (b) they can outgas nitrogen and oxygen, which then can react with the metal being deposited. Consequently, this innovation is expected to find use in the fabrication of transition edge sensors and microwave kinetic inductance detectors, which use thin superconducting films deposited at high temperature as their sensing elements. Transition edge sensors, microwave kinetic inductance detectors, and their circuitry are comprised of superconducting thin films, for example Nb and TiN. Reactive ion etching can be used to pattern these films; however, reactive ion etching also damages the underlying substrate, which is unwanted in many instances. Polymeric lift-off techniques permit thin-film patterning without any substrate damage, but they are difficult to remove and the polymer can outgas during thin-film deposition. The outgassed material can then react with the film with the consequence of altered and non-reproducible materials properties, which, in turn, is deleterious for sensors and their circuitry. The purpose of this innovation was to fabricate a germanium lift-off mask to be used for patterning thin metal films.

Automated general temperature correction method for dielectric soil moisture sensors

NASA Astrophysics Data System (ADS)

Kapilaratne, R. G. C. Jeewantinie; Lu, Minjiao

2017-08-01

An effective temperature correction method for dielectric sensors is important to ensure the accuracy of soil water content (SWC) measurements of local to regional-scale soil moisture monitoring networks. These networks are extensively using highly temperature sensitive dielectric sensors due to their low cost, ease of use and less power consumption. Yet there is no general temperature correction method for dielectric sensors, instead sensor or site dependent correction algorithms are employed. Such methods become ineffective at soil moisture monitoring networks with different sensor setups and those that cover diverse climatic conditions and soil types. This study attempted to develop a general temperature correction method for dielectric sensors which can be commonly used regardless of the differences in sensor type, climatic conditions and soil type without rainfall data. In this work an automated general temperature correction method was developed by adopting previously developed temperature correction algorithms using time domain reflectometry (TDR) measurements to ThetaProbe ML2X, Stevens Hydra probe II and Decagon Devices EC-TM sensor measurements. The rainy day effects removal procedure from SWC data was automated by incorporating a statistical inference technique with temperature correction algorithms. The temperature correction method was evaluated using 34 stations from the International Soil Moisture Monitoring Network and another nine stations from a local soil moisture monitoring network in Mongolia. Soil moisture monitoring networks used in this study cover four major climates and six major soil types. Results indicated that the automated temperature correction algorithms developed in this study can eliminate temperature effects from dielectric sensor measurements successfully even without on-site rainfall data. Furthermore, it has been found that actual daily average of SWC has been changed due to temperature effects of dielectric sensors with a significant error factor comparable to ±1% manufacturer's accuracy.

Application of Optical Imaging Techniques for Quantification of pH and O2 Dynamicsin Porous Media

NASA Astrophysics Data System (ADS)

Li, B.; Seliman, A. F.; Pales, A. R.; Liang, W.; Sams, A.; Darnault, C. J. G.; DeVol, T. A.

2016-12-01

Understanding the spatial and temporal distribution of physical and chemical parameters (e.g. pH, O2) is imperative to characterize the behavior of contaminants in a natural environment. The objectives of this research are to calibrate pH and O2 sensor foils, to develop a dual pH/O2 sensor foil, and to apply them into flow and transport experiments, in order to understand the physical and chemical parameters that control contaminant fate and transport in an unsaturated sandy porous medium. In addition, demonstration of a sensor foil that quantifies aqueous uranium concentration will be presented. Optical imaging techniques will be conducted with 2D tanks to investigate the influence of microbial exudates and plant roots on pH and O2 parameters and radionuclides transport. As a non-invasive method, the optical imaging technique utilizes optical chemical sensor films and either a digital camera or a spectrometer to capture the changes with high temporal and spatial resolutions. Sensor foils are made for different parameters by applying dyes to generate favorable fluorescence that is proportional to the parameter of interest. Preliminary results suggested that this method could detect pH ranging from 4.5 to 7.5. The result from uranium foil test with different concentrations in the range of 2 to 8 ppm indicated that a higher concentration of uranium resulted in a greater color intensity.

Miscellaneous methods for measuring matric or water potential

USGS Publications Warehouse

Scanlon, Bridget R.; Andraski, Brian J.; Bilskie, Jim; Dane, Jacob H.; Topp, G. Clarke

2002-01-01

A variety of techniques to measure matric potential or water potential in the laboratory and in the field are described in this section. The techniques described herein require equilibration of some medium whose matric or water potential can be determined from previous calibration or can be measured directly. Under equilibrium conditions the matric or water potential of the medium is equal to that of the soil. The techniques can be divided into: (i) those that measure matric potential and (ii) those that measure water potential (sum of matric and osmotic potentials). Matric potential is determined when the sensor matrix is in direct contact with the soil, so salts are free to diffuse in or out of the sensor matrix, and the equilibrium measurement therefore reflects matric forces acting on the water. Water potential is determined when the sensor is separated from the soil by a vapor gap, so salts are not free to move in or out of the sensor, and the equilibrium measurement reflects the sum of the matric and osmotic forces acting on the water.Seven different techniques are described in this section. Those that measure matric potential include (i) heat dissipation sensors, (ii) electrical resistance sensors, (iii) frequency domain and time domain sensors, and (iv) electro-optical switches. A method that can be used to measure matric potential or water potential is the (v) filter paper method. Techniques that measure water potential include (vi) the Dew Point Potentiameter (Decagon Devices, Inc., Pullman, WA1) (water activity meter) and (vii) vapor equilibration.The first four techniques are electronically based methods for measuring matric potential. Heat dissipation sensors and electrical resistance sensors infer matric potential from previously determined calibration relations between sensor heat dissipation or electrical resistance and matric potential. Frequency-domain and timedomain matric potential sensors measure water content, which is related to matric potential of the sensor through calibration. Electro-optical switches measure changes in light transmission through thin, nylon filters as they absorb or desorb water in response to changes in matric potential. Heat dissipation sensors and electrical resistance sensors are used primarily in the field to provide information on matric potential. Frequency domain matric potential sensors are new and have not been widely used. Time domain matric potential sensors and electro-optical switches are new and have not been commercialized. For the fifth technique, filter paper is used as the standard matrix. The filter paper technique measures matric potential when the filter paper is in direct contact with soil or water potential when separated from soil by a vapor gap. The Dew Point Potentiameter calculates water potential from the measured dew point and sample temperature. The vapor equilibration technique involves equilibration of soil samples with salt solutions of known osmotic potential. The filter paper, Dew Point Potentiameter, and vapor equilibration techniques are generally used in the laboratory to measure water potential of disturbed field samples or to measure water potential for water retention functions.

Advanced control techniques for teleoperation in earth orbit

NASA Technical Reports Server (NTRS)

Bejczy, A. K.; Brooks, T. L.

1980-01-01

Emerging teleoperation tasks in space invite advancements in teleoperator control technology. This paper briefly summarizes the generic issues related to earth orbital applications of teleoperators, and describes teleoperator control technology development work including visual and non-visual sensors and displays, kinesthetic feedback and computer-aided controls. Performance experiments were carried out using sensor and computer aided controls with promising results which are briefly summarized.

Unmanned Ground Vehicles for Integrated Force Protection

DTIC Science & Technology

2004-04-01

employed. 2 Force Protection 18 MAR 02 Security Posts Squad Laptop Fire Tm Ldr Wearable Computers OP/LP Def Fight Psn SRT Sensors USA, USMC, Allied...visual systems. Attaching sensors and response devices on a monorail proved to be much more technically challenging than expected. Film producers and...facilitate experimentation with weapon aiming and firing techniques from the MRHA. grated Marsupial Delivery System was developed to transport smaller

In situ optical water-quality sensor networks - Workshop summary report

USGS Publications Warehouse

Pellerin, Brian A.; Bergamaschi, Brian A.; Horsburgh, Jeffery S.

2012-01-01

Advanced in situ optical water-quality sensors and new techniques for data analysis hold enormous promise for furthering scientific understanding of aquatic systems. These sensors measure important biogeochemical parameters for long deployments, enabling the capture of data at time scales over which they vary most meaningfully. The high-frequency, real-time water-quality data they generate provide opportunities for early warning of water-quality deterioration, trend detection, and science-based decision support. However, developing networks of optical sensors in freshwater systems that report reliable and comparable data across and between sites remains a challenge to the research and monitoring community. To address this, the U. S. Geological Survey (USGS) and the Consortium of Universities for the Advancement of Hydrologic Science, Inc. (CUAHSI) convened a joint 3-day workshop (June 8-10, 2011) at the National Conservation Training Center in Shepardstown, West Virginia, to explore ways to coordinate development of standards and applications for optical sensors, and improve handling, storing, and analyzing the continuous data they produce. The workshop brought together more than 60 scientists, program managers, and vendors from universities, government agencies, and the private sector. Several important outcomes emerged from the presentations and breakout sessions. There was general consensus that making intercalibrated measurements requires that both manufacturers and users better characterize and calibrate the sensors under field conditions. For example, the influence of suspended particles, highly colored water, and temperature on optical sensors remains poorly understood, but consistently accounting for these factors is critical to successful deployment and for interpreting results in different settings. This, in turn, highlights the lack of appropriate standards for sensor calibrations, field checks, and characterizing interferences, as well as methods for data validation, treatment, and analysis of resulting measurements. Participants discussed a wide range of logistical considerations for successful sensor deployments, including key physical infrastructure, data loggers, and remote-communication techniques. Tools to manage, assure, and control quality, and explore large streams of continuous water-quality data are being developed by the USGS, CUAHSI, and other organizations, and will be critical to making full use of these highfrequency data for research and monitoring.

Field Calibration of Wind Direction Sensor to the True North and Its Application to the Daegwanryung Wind Turbine Test Sites

PubMed Central

Lee, Jeong Wan

2008-01-01

This paper proposes a field calibration technique for aligning a wind direction sensor to the true north. The proposed technique uses the synchronized measurements of captured images by a camera, and the output voltage of a wind direction sensor. The true wind direction was evaluated through image processing techniques using the captured picture of the sensor with the least square sense. Then, the evaluated true value was compared with the measured output voltage of the sensor. This technique solves the discordance problem of the wind direction sensor in the process of installing meteorological mast. For this proposed technique, some uncertainty analyses are presented and the calibration accuracy is discussed. Finally, the proposed technique was applied to the real meteorological mast at the Daegwanryung test site, and the statistical analysis of the experimental testing estimated the values of stable misalignment and uncertainty level. In a strict sense, it is confirmed that the error range of the misalignment from the exact north could be expected to decrease within the credibility level. PMID:27873957

Motion camera based on a custom vision sensor and an FPGA architecture

NASA Astrophysics Data System (ADS)

Arias-Estrada, Miguel

1998-09-01

A digital camera for custom focal plane arrays was developed. The camera allows the test and development of analog or mixed-mode arrays for focal plane processing. The camera is used with a custom sensor for motion detection to implement a motion computation system. The custom focal plane sensor detects moving edges at the pixel level using analog VLSI techniques. The sensor communicates motion events using the event-address protocol associated to a temporal reference. In a second stage, a coprocessing architecture based on a field programmable gate array (FPGA) computes the time-of-travel between adjacent pixels. The FPGA allows rapid prototyping and flexible architecture development. Furthermore, the FPGA interfaces the sensor to a compact PC computer which is used for high level control and data communication to the local network. The camera could be used in applications such as self-guided vehicles, mobile robotics and smart surveillance systems. The programmability of the FPGA allows the exploration of further signal processing like spatial edge detection or image segmentation tasks. The article details the motion algorithm, the sensor architecture, the use of the event- address protocol for velocity vector computation and the FPGA architecture used in the motion camera system.

Review of model sensor studies on Pd/SnO2(110) surfaces

NASA Technical Reports Server (NTRS)

Fryberger, Teresa B.; Semancik, Steve

1990-01-01

Studies performed at the National Institute of Standards and Technology on the model gas sensor system, Pd/SnO2(110), are reviewed. Adsorption and interfacial effects play a primary role in the gas sensing process, as they do in catalysis. For this reason, researchers have used a variety of surface sensitive techniques in the research, including x ray and ultraviolet photoelectron spectroscopies (XPS and UPS), low energy electron diffraction (LEED), and ion scattering spectroscopy (ISS). By combining these complementary techniques with in situ gas response (conductance) measurements, researchers were able to correlate directly sensor activity with the composition and structure of the Pd/SnO2 interface. Although the intent of this work is to develop an understanding of gas sensing mechanisms, its relevance to Pt/SnO2 catalytic systems is obvious.

Applications of Wireless Sensor Networks in Marine Environment Monitoring: A Survey

PubMed Central

Xu, Guobao; Shen, Weiming; Wang, Xianbin

2014-01-01

With the rapid development of society and the economy, an increasing number of human activities have gradually destroyed the marine environment. Marine environment monitoring is a vital problem and has increasingly attracted a great deal of research and development attention. During the past decade, various marine environment monitoring systems have been developed. The traditional marine environment monitoring system using an oceanographic research vessel is expensive and time-consuming and has a low resolution both in time and space. Wireless Sensor Networks (WSNs) have recently been considered as potentially promising alternatives for monitoring marine environments since they have a number of advantages such as unmanned operation, easy deployment, real-time monitoring, and relatively low cost. This paper provides a comprehensive review of the state-of-the-art technologies in the field of marine environment monitoring using wireless sensor networks. It first describes application areas, a common architecture of WSN-based oceanographic monitoring systems, a general architecture of an oceanographic sensor node, sensing parameters and sensors, and wireless communication technologies. Then, it presents a detailed review of some related projects, systems, techniques, approaches and algorithms. It also discusses challenges and opportunities in the research, development, and deployment of wireless sensor networks for marine environment monitoring. PMID:25215942

Frontiers in Chemical Sensors: Novel Principles and Techniques

NASA Astrophysics Data System (ADS)

Orellana, Guillermo; Moreno-Bondi, Maria Cruz

This third volume of Springer Series on Chemical Sensors and Biosensors aims to enable the researcher or technologist to become acquainted with the latest principles and techniques that keep on enlarging the applications in this fascinating field. It deals with the novel luminescence lifetime-based techniques for interrogation of sensor arrays in high-throughput screening, cataluminescence, chemical sensing with hollow waveguides, new ways in sensor design and fabrication by means of either combinatorial methods or engineered indicator/support couples.

Estimating propagation velocity through a surface acoustic wave sensor

DOEpatents

Xu, Wenyuan; Huizinga, John S.

2010-03-16

Techniques are described for estimating the propagation velocity through a surface acoustic wave sensor. In particular, techniques which measure and exploit a proper segment of phase frequency response of the surface acoustic wave sensor are described for use as a basis of bacterial detection by the sensor. As described, use of velocity estimation based on a proper segment of phase frequency response has advantages over conventional techniques that use phase shift as the basis for detection.

Research study of pressure instrumentation

NASA Technical Reports Server (NTRS)

Hoogenboom, L.; Hull-Allen, G.

1984-01-01

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

Information integration and diagnosis analysis of equipment status and production quality for machining process

NASA Astrophysics Data System (ADS)

Zan, Tao; Wang, Min; Hu, Jianzhong

2010-12-01

Machining status monitoring technique by multi-sensors can acquire and analyze the machining process information to implement abnormity diagnosis and fault warning. Statistical quality control technique is normally used to distinguish abnormal fluctuations from normal fluctuations through statistical method. In this paper by comparing the advantages and disadvantages of the two methods, the necessity and feasibility of integration and fusion is introduced. Then an approach that integrates multi-sensors status monitoring and statistical process control based on artificial intelligent technique, internet technique and database technique is brought forward. Based on virtual instrument technique the author developed the machining quality assurance system - MoniSysOnline, which has been used to monitoring the grinding machining process. By analyzing the quality data and AE signal information of wheel dressing process the reason of machining quality fluctuation has been obtained. The experiment result indicates that the approach is suitable for the status monitoring and analyzing of machining process.

A low-cost, portable, high-throughput wireless sensor system for phonocardiography applications.

PubMed

Sa-Ngasoongsong, Akkarapol; Kunthong, Jakkrit; Sarangan, Venkatesh; Cai, Xinwei; Bukkapatnam, Satish T S

2012-01-01

This paper presents the design and testing of a wireless sensor system developed using a Microchip PICDEM developer kit to acquire and monitor human heart sounds for phonocardiography applications. This system can serve as a cost-effective option to the recent developments in wireless phonocardiography sensors that have primarily focused on Bluetooth technology. This wireless sensor system has been designed and developed in-house using off-the-shelf components and open source software for remote and mobile applications. The small form factor (3.75 cm × 5 cm × 1 cm), high throughput (6,000 Hz data streaming rate), and low cost ($13 per unit for a 1,000 unit batch) of this wireless sensor system make it particularly attractive for phonocardiography and other sensing applications. The experimental results of sensor signal analysis using several signal characterization techniques suggest that this wireless sensor system can capture both fundamental heart sounds (S1 and S2), and is also capable of capturing abnormal heart sounds (S3 and S4) and heart murmurs without aliasing. The results of a denoising application using Wavelet Transform show that the undesirable noises of sensor signals in the surrounding environment can be reduced dramatically. The exercising experiment results also show that this proposed wireless PCG system can capture heart sounds over different heart conditions simulated by varying heart rates of six subjects over a range of 60-180 Hz through exercise testing.

A Low-Cost, Portable, High-Throughput Wireless Sensor System for Phonocardiography Applications

PubMed Central

Sa-ngasoongsong, Akkarapol; Kunthong, Jakkrit; Sarangan, Venkatesh; Cai, Xinwei; Bukkapatnam, Satish T. S.

2012-01-01

This paper presents the design and testing of a wireless sensor system developed using a Microchip PICDEM developer kit to acquire and monitor human heart sounds for phonocardiography applications. This system can serve as a cost-effective option to the recent developments in wireless phonocardiography sensors that have primarily focused on Bluetooth technology. This wireless sensor system has been designed and developed in-house using off-the-shelf components and open source software for remote and mobile applications. The small form factor (3.75 cm × 5 cm × 1 cm), high throughput (6,000 Hz data streaming rate), and low cost ($13 per unit for a 1,000 unit batch) of this wireless sensor system make it particularly attractive for phonocardiography and other sensing applications. The experimental results of sensor signal analysis using several signal characterization techniques suggest that this wireless sensor system can capture both fundamental heart sounds (S1 and S2), and is also capable of capturing abnormal heart sounds (S3 and S4) and heart murmurs without aliasing. The results of a denoising application using Wavelet Transform show that the undesirable noises of sensor signals in the surrounding environment can be reduced dramatically. The exercising experiment results also show that this proposed wireless PCG system can capture heart sounds over different heart conditions simulated by varying heart rates of six subjects over a range of 60–180 Hz through exercise testing. PMID:23112633

Dielectric permitivity measurement of cotton lint

USDA-ARS?s Scientific Manuscript database

A technique was developed for making broad band measurements of cotton lint electrical permitivity. The fundamental electrical permitivity value of cotton lint at various densities and moisture contents; is beneficial for the future development of cotton moisture sensors as it provides a...

A miniature 48-channel pressure sensor module capable of in situ calibration

NASA Technical Reports Server (NTRS)

Gross, C.; Juanarena, D. B.

1977-01-01

A new high data rate pressure sensor module with in situ calibration capability has been developed by the Langley Research Center to help reduce energy consumption in wind-tunnel facilities without loss of measurement accuracy. The sensor module allows for nearly a two order of magnitude increase in data rates over conventional electromechanically scanned pressure sampling techniques. This module consists of 16 solid state pressure sensor chips and signal multiplexing electronics integrally mounted to a four position pressure selector switch. One of the four positions of the pressure selector switch allows the in situ calibration of the 16 pressure sensors; the three other positions allow 48 channels (three sets of 16) pressure inputs to be measured by sensors. The small size of the sensor module will allow mounting within many wind-tunnel models, thus eliminating long tube lengths and their corresponding slow pressure response.

Sensor Alerting Capability

NASA Astrophysics Data System (ADS)

Henriksson, Jakob; Bermudez, Luis; Satapathy, Goutam

2013-04-01

There is a large amount of sensor data generated today by various sensors, from in-situ buoys to mobile underwater gliders. Providing sensor data to the users through standardized services, language and data model is the promise of OGC's Sensor Web Enablement (SWE) initiative. As the amount of data grows it is becoming difficult for data providers, planners and managers to ensure reliability of data and services and to monitor critical data changes. Intelligent Automation Inc. (IAI) is developing a net-centric alerting capability to address these issues. The capability is built on Sensor Observation Services (SOSs), which is used to collect and monitor sensor data. The alerts can be configured at the service level and at the sensor data level. For example it can alert for irregular data delivery events or a geo-temporal statistic of sensor data crossing a preset threshold. The capability provides multiple delivery mechanisms and protocols, including traditional techniques such as email and RSS. With this capability decision makers can monitor their assets and data streams, correct failures or be alerted about a coming phenomena.

Semiselective Optoelectronic Sensors for Monitoring Microbes

NASA Technical Reports Server (NTRS)

Tabacco, Mary Beth; Chuang, Han; Taylor,Laura; Russo, Jaime

2003-01-01

Sensor systems are under development for use in real-time detection and quantitation of microbes in water without need for sampling. These systems include arrays of optical sensors; miniature, portable electronic data-acquisition circuits; and optoelectronic interfaces between the sensor arrays and data-acquisition circuits. These systems are intended for original use in long-term, inline monitoring of waterborne micro-organisms in water-reclamation systems aboard future spacecraft. They could also be adapted to similar terrestrial uses with respect to municipal water supplies, stored drinking water, and swimming water; for detecting low-level biological contamination in biotechnological, semiconductor, and pharmaceutical process streams; and in verifying the safety of foods and beverages. In addition, they could be adapted to monitoring of airborne microbes and of surfaces (e.g., to detect and/or quantitate biofilms). The designs of the sensors in these systems are based partly on those of sensors developed previously for monitoring airborne biological materials. The designs exploit molecular- recognition and fluorescence-spectroscopy techniques, such that in the presence of micro-organisms of interest, fluorescence signals change and the changes can be measured. These systems are characterized as semiselective because they respond to classes of micro-organisms and can be used to discriminate among the classes. This semiselectivity is a major aspect of the design: It is important to distinguish between (1) the principle of detection and quantitation of classes of micro-organisms by use of these sensors and (2) the principle of detection and quantitation of individual microbiological species by means of prior immuno-diagnostic and/or molecular-biology techniques. Detection of classes (in contradistinction to species) is particularly valuable when the exact nature of a contaminant is unknown.

Commercialization Issues For Catheter-Based Electrochemical Sensors

NASA Astrophysics Data System (ADS)

Nikolchev, Julian; Gaisford, Scott

1989-08-01

The need for continuous monitoring of key clinical parameters in hospitals is well recognized. Figure 1 shows typical time constants for blood gases, ions and enzymes in response to acute ventilatory changes and interventions. Although it can be seen that relatively low rates of data collection are necessary for many medical measurements, it is also clear that intermittent measurement of P02, PCO2 and pH are not sufficient to provide safe and effective management of the patient. Very frequent or continuous monitoring is often essential. This figure also shows why the emphasis of a large number of research efforts in this country and in Europe and Japan have as their goal the development of continuous blood gas sensors, i.e., sensors that continuously monitor blood pH, partial pressure of oxygen and partial pressure of carbon dioxide. These are three (3) of the most frequent parameters measured in hospitals and the ones having the shortest time constant. Considering that in the United States alone close to 25 million blood gas samples per year are taken from patients, the potential market for continuous monitoring sensors is enormous. The emergence of microelectronics and microfabrication technologies over the past 30 years are now pointing to a possible resolution of the well recognized need for real time monitoring of critically ill patients through catheter-based sensors. Although physicians will always prefer non-invasive monitoring techniques, there are a number of parameters that presently can only be monitored by invasive method. The emerging ability to miniaturize chemical sensors using silicon microfabrication or fiber-optic techniques offer an excellent opportunity to solve this need. In fact, the development of in vivo biomedical sensors with satisfactory performance characteristics has long been considered the ultimate application of these emerging technologies.

On the development of a magnetoresistive sensor for blade tip timing and blade tip clearance measurement systems

NASA Astrophysics Data System (ADS)

Tomassini, R.; Rossi, G.; Brouckaert, J.-F.

2014-05-01

The accurate control of the gap between static and rotating components is vital to preserve the mechanical integrity and ensure a correct functioning of any rotating machinery. Moreover, tip leakage above the airfoil tip results in relevant aerodynamic losses. One way to measure and to monitor blade tip gaps is by the so-called Blade Tip Clearance (BTC) technique. Another fundamental phenomenon to control in the turbomachines is the vibration of the blades. For more than half a century, this has been performed by installing strain gauges on the blades and using telemetry to transmit the signals. The Blade Tip Timing (BTT) technique, (i.e. measuring the blade time of arrival from the casing at different angular locations with proximity sensors) is currently being adopted by all manufacturers as a replacement for the classical strain gauge technique because of its non-intrusive character. This paper presents a novel magnetoresistive sensor for blade tip timing and blade tip clearance systems, which offers high temporal and high spatial resolution simultaneously. The sensing element adopted is a Wheatstone bridge of Permalloy elements. The principle of the sensor is based on the variation of magnetic field at the passage of ferromagnetic objects. Two different configurations have been realized, a digital and an analogue sensor. Measurements of tip clearance have been performed in an high speed compressor and the calibration curve is reported. Measurements of blade vibration have been carried out in a dedicated calibration bench; results are presented and discussed. The magnetoresistive sensor is characterized by high repeatability, low manufacturing costs and measurement accuracy in line with the main probes used in turbomachinery testing. The novel sensor has great potential and is capable of fulfilling the requirements for a simultaneous BTC and BTT measurement system.

Electrochemical Sensors and Biosensors Based on Nanomaterials and Nanostructures

DOE PAGES

Zhu, Chengzhou; Yang, Guohai; Li, He; ...

2014-10-29

We report that considerable attention has been devoted to the integration of recognition elements with electronic elements to develop electrochemical sensors and biosensors.Various electrochemical devices, such as amperometric sensors, electrochemical impedance sensors, and electrochemical luminescence sensors as well as photoelectrochemical sensors, provide wide applications in the detection of chemical and biological targets in terms of electrochemical change of electrode interfaces. Here, this review focuses on recent advances in electrochemical sensors and biosensors based on nanomaterials and nanostructures during 2013 to 2014. The aim of this effort is to provide the reader with a clear and concise view of new advancesmore » in areas ranging from electrode engineering, strategies for electrochemical signal amplification, and novel electroanalytical techniques used in the miniaturization and integration of the sensors. Moreover, the authors have attempted to highlight areas of the latest and significant development of enhanced electrochemical nanosensors and nanobiosensors that inspire broader interests across various disciplines. Electrochemical sensors for small molecules, enzyme-based biosensors, genosensors, immunosensors, and cytosensors are reviewed herein (Figure 1). Such novel advances are important for the development of electrochemical sensors that open up new avenues and methods for future research. In conclusion, we recommend readers interested in the general principles of electrochemical sensors and electrochemical methods to refer to other excellent literature for a broad scope in this area.(3, 4) However, due to the explosion of publications in this active field, we do not claim that this Review includes all of the published works in the past two years and we apologize to the authors of excellent work, which is unintentionally left out.« less

The development of a solid-state hydrogen sensor for rocket engine leakage detection

NASA Technical Reports Server (NTRS)

Liu, Chung-Chiun

1994-01-01

Hydrogen propellant leakage poses significant operational problems in the rocket propulsion industry as well as for space exploratory applications. Vigorous efforts have been devoted to minimizing hydrogen leakage in assembly, test, and launch operations related to hydrogen propellant. The objective has been to reduce the operational cost of assembling and maintaining hydrogen delivery systems. Specifically, efforts have been made to develop a hydrogen leak detection system for point-contact measurement. Under the auspices of Lewis Research Center, the Electronics Design Center at Case Western Reserve University, Cleveland, Ohio, has undertaken the development of a point-contact hydrogen gas sensor with potential applications to the hydrogen propellant industry. We envision a sensor array consisting of numbers of discrete hydrogen sensors that can be located in potential leak sites. Silicon-based microfabrication and micromachining techniques are used in the fabrication of these sensor prototypes. Evaluations of the sensor are carried out in-house at Case Western Reserve University as well as at Lewis Research Center and GenCorp Aerojet, Sacramento, California. The hydrogen gas sensor is not only applicable in a hydrogen propulsion system, but also usable in many other civilian and industrial settings. This includes vehicles or facility use, or in the production of hydrogen gas. Dual space and commercial uses of these point-contacted hydrogen sensors are feasible and will directly meet the needs and objectives of NASA as well as various industrial segments.

The development of a solid-state hydrogen sensor for rocket engine leakage detection

NASA Astrophysics Data System (ADS)

Liu, Chung-Chiun

Hydrogen propellant leakage poses significant operational problems in the rocket propulsion industry as well as for space exploratory applications. Vigorous efforts have been devoted to minimizing hydrogen leakage in assembly, test, and launch operations related to hydrogen propellant. The objective has been to reduce the operational cost of assembling and maintaining hydrogen delivery systems. Specifically, efforts have been made to develop a hydrogen leak detection system for point-contact measurement. Under the auspices of Lewis Research Center, the Electronics Design Center at Case Western Reserve University, Cleveland, Ohio, has undertaken the development of a point-contact hydrogen gas sensor with potential applications to the hydrogen propellant industry. We envision a sensor array consisting of numbers of discrete hydrogen sensors that can be located in potential leak sites. Silicon-based microfabrication and micromachining techniques are used in the fabrication of these sensor prototypes. Evaluations of the sensor are carried out in-house at Case Western Reserve University as well as at Lewis Research Center and GenCorp Aerojet, Sacramento, California. The hydrogen gas sensor is not only applicable in a hydrogen propulsion system, but also usable in many other civilian and industrial settings. This includes vehicles or facility use, or in the production of hydrogen gas. Dual space and commercial uses of these point-contacted hydrogen sensors are feasible and will directly meet the needs and objectives of NASA as well as various industrial segments.

Ripeness sensor development. Final report

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

Not Available

1992-11-01

About 20--25% of the total production of fruits and vegetables in the USA must be discarded after harvest About 25--30% of this loss is the result of over-ripening and this loss represents about 8.39 {times} 10{sup 12} BTU of invested energy every year. This invested energy could be saved by non-destructive ripeness sensing. Sweetness is an important indicator of fruit quality and highly correlated with ripeness in most fruits. Research to develop a non-destructive fruit ripeness sensor has been conducted in the Agricultural Engineering Department at Purdue University. It is based on {sup 1}H-MR (proton Magnetic Resonance). A first generationmore » prototype of the ripeness sensor based on {sup 1}H-MR was built and tested with. Results show that the sensor can discriminate small fruit (0.75 in diameter or smaller) differing in sugar content by 6%. This prototype can separate the fruit into at least two groups: one ripe and the other not ripe. The estimated cost for such a ripeness sensor is around $4,000. The signal sensitivity of the prototype can be improved to enable it to differentiate between fruits varying in sugar content by only 1 or 2% by using water peak suppression techniques to recover relatively weak sugar resonance signals in intact fruits, modifying circuits to eliminate noise, leakage and distortion of input/output signals, improving the magnetic console to get a higher magnetic field and better homogeneity, and designing a probe to achieve a higher signal-to-noise (S/N) ratio. As research continues a second generation ripeness sensor will be developed which will incorporate many of the improvements and which will be suitable for commercial use. Additional research will allow application of the technique to a wider range of fruit sizes (from blueberries to watermelons). This report describes estimated energy savings, feasibility studies, development of the initial prototype, and preliminary evaluation of the first generation prototype.« less

Ripeness sensor development

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

Not Available

1992-11-01

About 20--25% of the total production of fruits and vegetables in the USA must be discarded after harvest About 25--30% of this loss is the result of over-ripening and this loss represents about 8.39 [times] 10[sup 12] BTU of invested energy every year. This invested energy could be saved by non-destructive ripeness sensing. Sweetness is an important indicator of fruit quality and highly correlated with ripeness in most fruits. Research to develop a non-destructive fruit ripeness sensor has been conducted in the Agricultural Engineering Department at Purdue University. It is based on [sup 1]H-MR (proton Magnetic Resonance). A first generationmore » prototype of the ripeness sensor based on [sup 1]H-MR was built and tested with. Results show that the sensor can discriminate small fruit (0.75 in diameter or smaller) differing in sugar content by 6%. This prototype can separate the fruit into at least two groups: one ripe and the other not ripe. The estimated cost for such a ripeness sensor is around $4,000. The signal sensitivity of the prototype can be improved to enable it to differentiate between fruits varying in sugar content by only 1 or 2% by using water peak suppression techniques to recover relatively weak sugar resonance signals in intact fruits, modifying circuits to eliminate noise, leakage and distortion of input/output signals, improving the magnetic console to get a higher magnetic field and better homogeneity, and designing a probe to achieve a higher signal-to-noise (S/N) ratio. As research continues a second generation ripeness sensor will be developed which will incorporate many of the improvements and which will be suitable for commercial use. Additional research will allow application of the technique to a wider range of fruit sizes (from blueberries to watermelons). This report describes estimated energy savings, feasibility studies, development of the initial prototype, and preliminary evaluation of the first generation prototype.« less

Finite element modelling of fibre Bragg grating strain sensors and experimental validation

NASA Astrophysics Data System (ADS)

Malik, Shoaib A.; Mahendran, Ramani S.; Harris, Dee; Paget, Mark; Pandita, Surya D.; Machavaram, Venkata R.; Collins, David; Burns, Jonathan M.; Wang, Liwei; Fernando, Gerard F.

2009-03-01

Fibre Bragg grating (FBG) sensors continue to be used extensively for monitoring strain and temperature in and on engineering materials and structures. Previous researchers have also developed analytical models to predict the loadtransfer characteristics of FBG sensors as a function of applied strain. The general properties of the coating or adhesive that is used to surface-bond the FBG sensor to the substrate has also been modelled using finite element analysis. In this current paper, a technique was developed to surface-mount FBG sensors with a known volume and thickness of adhesive. The substrates used were aluminium dog-bone tensile test specimens. The FBG sensors were tensile tested in a series of ramp-hold sequences until failure. The reflected FBG spectra were recorded using a commercial instrument. Finite element analysis was performed to model the response of the surface-mounted FBG sensors. In the first instance, the effect of the mechanical properties of the adhesive and substrate were modelled. This was followed by modelling the volume of adhesive used to bond the FBG sensor to the substrate. Finally, the predicted values obtained via finite element modelling were correlated to the experimental results. In addition to the FBG sensors, the tensile test specimens were instrumented with surface-mounted electrical resistance strain gauges.

Fiber Optic Sensors for Health Monitoring of Morphing Aircraft

NASA Technical Reports Server (NTRS)

Brown, Timothy; Wood, Karen; Childers, Brooks; Cano, Roberto; Jensen, Brian; Rogowski, Robert

2001-01-01

Fiber optic sensors are being developed for health monitoring of future aircraft. Aircraft health monitoring involves the use of strain, temperature, vibration and chemical sensors. These sensors will measure load and vibration signatures that will be used to infer structural integrity. Sine the aircraft morphing program assumes that future aircraft will be aerodynamically reconfigurable there is also a requirement for pressure, flow and shape sensors. In some cases a single fiber may be used for measuring several different parameters. The objective of the current program is to develop techniques for using optical fibers to monitor composite cure in real time during manufacture and to monitor in-service structural integrity of the composite structure. Graphite-epoxy panels were fabricated with integrated optical fibers of various types. The panels were mechanically and thermally tested to evaluate composite strength and sensor durability. Finally the performance of the fiber optic sensors was determined. Experimental results are presented evaluating the performance of embedded and surface mounted optical fibers for measuring strain, temperature and chemical composition. The performance of the fiber optic sensors was determined by direct comparison with results from more conventional instrumentation. The facilities for fabricating optical fiber and associated sensors and methods of demodulating Bragg gratings for strain measurement will be described.

Integrated approach for automatic target recognition using a network of collaborative sensors.

PubMed

Mahalanobis, Abhijit; Van Nevel, Alan

2006-10-01

We introduce what is believed to be a novel concept by which several sensors with automatic target recognition (ATR) capability collaborate to recognize objects. Such an approach would be suitable for netted systems in which the sensors and platforms can coordinate to optimize end-to-end performance. We use correlation filtering techniques to facilitate the development of the concept, although other ATR algorithms may be easily substituted. Essentially, a self-configuring geometry of netted platforms is proposed that positions the sensors optimally with respect to each other, and takes into account the interactions among the sensor, the recognition algorithms, and the classes of the objects to be recognized. We show how such a paradigm optimizes overall performance, and illustrate the collaborative ATR scheme for recognizing targets in synthetic aperture radar imagery by using viewing position as a sensor parameter.

First-time demonstration of measuring concrete prestress levels with metal packaged fibre optic sensors

NASA Astrophysics Data System (ADS)

Mckeeman, I.; Fusiek, G.; Perry, M.; Johnston, M.; Saafi, M.; Niewczas, P.; Walsh, M.; Khan, S.

2016-09-01

In this work we present the first large-scale demonstration of metal packaged fibre Bragg grating sensors developed to monitor prestress levels in prestressed concrete. To validate the technology, strain and temperature sensors were mounted on steel prestressing strands in concrete beams and stressed up to 60% of the ultimate tensile strength of the strand. We discuss the methods and calibration procedures used to fabricate and attach the temperature and strain sensors. The use of induction brazing for packaging the fibre Bragg gratings and welding the sensors to prestressing strands eliminates the use of epoxy, making the technique suitable for high-stress monitoring in an irradiated, harsh industrial environment. Initial results based on the first week of data after stressing the beams show the strain sensors are able to monitor prestress levels in ambient conditions.

Advancing Porous Silicon Biosensor Technology for Use in Clinical Diagnostics

NASA Astrophysics Data System (ADS)

Bonanno, Lisa Marie

Inexpensive and robust analytical techniques for detecting molecular recognition events are in great demand in healthcare, food safety, and environmental monitoring. Despite vast research in this area, challanges remain to develop practical biomolecular platforms that, meet the rigorous demands of real-world applications. This includes maintaining low-cost devices that are sensitive and specific in complex test specimens, are stable after storage, have short assay time, and possess minimal complexity of instrumentation for readout. Nanostructured porous silicon (PSi) material has been identified as an ideal candidate towards achieving these goals and the past decade has seen diverse proof-of-principle studies developing optical-based sensing techniques. In Part 1 of this thesis, the impact of surface chemistry and PSi morphology on detection sensitivity of target molecules is investigated. Initial proof-of-concept that PSi devices facilitate detection of protein in whole blood is demonstrated. This work highlights the importance of material stability and blocking chemistry for sensor use in real world biological samples. In addition, the intrinisic filtering capability of the 3-D PSi morphology is shown as an advantage in complex solutions, such as whole blood. Ultimately, this initial work identified a need to improve detection sensitivity of the PSI biosensor technique to facilitate clinical diagnostic use over relevant target concentration ranges. The second part of this thesis, builds upon sensitivity challenges that are highlighted in the first part of the thesis and development of a surface-bound competitive inhibition immunoassay facilitated improved detection sensitivity of small molecular weight targets (opiates) over a relevant clinical concentration range. In addition, optimization of assay protocol addressed issues of maintaining stability of sensors after storage. Performance of the developed assay (specificity and sensitivity) was then validated in a blind clinical study that screened real patient urine samples (n=70) for opiates in collaboration with Strong Memorial Hospital Clinical Toxicology Laboratory. PSI sensor results showed improved clinical specificity over current commercial opiate immunoassay techniques and therefore, identified potential for a reduction in false-negative and false-positive screening results. Here, we demonstrate for the first time, successful clinical capability of a PSi sensor to detect opiates as a model target in real-world patient samples. The final part of this thesis explores novel sensor designs to leverage the tunable optical properties of PSi photonic devices and facilitate colorimetric readout of molecular recognition events by the unaided eye. Such a design is ideal for uncomplicated diagnostic screening at point-of-care as no instrumentation is needed for result readout. The photonic PSi transducers were integrated with target analyte-responsive hydrogels (TRAP-gels) that upon exposure to a target solution would swell and dissolute, inducing material property changes that were optically detected by the incorporated PSi transducer. This strategy extends target detection throughout the 3-ll internal volume of the PSi, improving upon current techniques that limit detection to the surface area (2-ll) of PSi. Work to acheive this approach involved design of TRAP-gel networks, polymer synthesis and characterization techniques, and optical characterization of the hybrid hydrogel-PSi material sensor. Successful implementation of a hybrid sensor design was exhibited for a. model chemical target (reducing agent), in which visual colorimetric change from red to green was observed for above-threshold exposure to the chemical target. In addition, initial proof-of-concept of an opiate responsive TRAP-gel is also demonstrated where cross-links are formed between antibody-antigen interactions and exposure to opiates induces bulk gel dissolution.

Fieldable Fourier transform spectrometer

NASA Astrophysics Data System (ADS)

Hatchell, Brian K.; Harper, Warren W.; Schultz, John F.

2004-10-01

The infrared sensors group at the Pacific Northwest National Laboratory (PNNL) is focused on the science and technology of remote and in-situ chemical sensors for detecting proliferation and countering terrorism. To support these vital missions, PNNL is developing frequency-modulation techniques for remote probing over long optical paths by means of differential-absorption light detecting and ranging (LIDAR). This technique can easily monitor large areas, or volumes, that could only be accomplished with a large network of point sensors. Recently, PNNL began development of a rugged frequency-modulation differential-abosrption LIDAR (FM-DIAL) system to conduct field experiments. To provide environmentla protection for the system and facilitate field deployments and operations, a large, well insulated, temperature controlled trailer was specified and acquired. The trailer was outfitted with a shock-mounted optical bench, an electronics rack, a liquid nitrogen Dewar, and a power generator. A computer-controlled gimbal-mounted mirror was added to allow the telescope beam to be accurately pointed in both the vertical and horizontal plane. This turned out to be the most complicated addition, and is described in detail. This paper provides an overview of the FM-DIAL system and illustrates innovative solutions developed to overcome several alignment and stability issues encountered in the field.

From Data Acquisition to Data Fusion: A Comprehensive Review and a Roadmap for the Identification of Activities of Daily Living Using Mobile Devices

PubMed Central

Pires, Ivan Miguel; Garcia, Nuno M.; Pombo, Nuno; Flórez-Revuelta, Francisco

2016-01-01

This paper focuses on the research on the state of the art for sensor fusion techniques, applied to the sensors embedded in mobile devices, as a means to help identify the mobile device user’s daily activities. Sensor data fusion techniques are used to consolidate the data collected from several sensors, increasing the reliability of the algorithms for the identification of the different activities. However, mobile devices have several constraints, e.g., low memory, low battery life and low processing power, and some data fusion techniques are not suited to this scenario. The main purpose of this paper is to present an overview of the state of the art to identify examples of sensor data fusion techniques that can be applied to the sensors available in mobile devices aiming to identify activities of daily living (ADLs). PMID:26848664

All-fiber loading sensor based on 45° and 81° tilted fiber gratings

NASA Astrophysics Data System (ADS)

Sun, Zhongyuan; Yan, Zhijun; Mou, Chengbo; Wang, Xiangchuan; Li, Jianfeng; Zhang, Lin

2014-05-01

Cardiovascular health of the human population is a major concern for medical clinicians, with cardiovascular diseases responsible for 48% of all deaths worldwide, according to the World Health Organisation. Therefore the development of new practicable and economical diagnostic tools to scrutinise the cardiovascular health of humans is a major driver for clinicians. We offer a new technique to obtain seismocardiographic signals covering both ballistocardiography (below 20Hz) and audible heart sounds (20Hz upwards). The detection scheme is based upon an array of curvature/displacement sensors using fibre optic long period gratings interrogated using a variation of the derivative spectroscopy interrogation technique

Snowpack ground-truth manual

NASA Technical Reports Server (NTRS)

Jones, E. B.

1983-01-01

As remote sensing increasingly becomes more of an operational tool in the field of snow management and snow hydrology, there is need for some degree of standardization of ""snowpack ground truth'' techniques. This manual provides a first step in standardizing these procedures and was prepared to meet the needs of remote sensing researchers in planning missions requiring ground truth as well as those providing the ground truth. Focus is on ground truth for remote sensors primarily operating in the microwave portion of the electromagnetic spectrum; nevertheless, the manual should be of value to other types of sensor programs. This first edition of ground truth procedures must be updated as new or modified techniques are developed.

Role of passive remote sensors. Sensor System Panel report

NASA Astrophysics Data System (ADS)

1982-06-01

Capabilities of present passive systems are described and the development of passive remote sensing systems for the more abundant tropospheric trace species is recommended. The combination of nadir-viewing spectrometers and solar occultation for tropospheric measurement of those gases having large stratospheric burdens is discussed. Development of a nadir-viewing instrument capable of obtaining continuous spectra in narrower bands is recommended. Gas filter radiometers for species specific measurements and development of a spectral survey instrument are discussed. Further development of aerosol retrieval algorithms, including polarization techniques, for obtaining aerosol thickness and size distributions is advised. Recommendations of specific investigations to be pursued are presented.

Role of passive remote sensors. Sensor System Panel report

NASA Technical Reports Server (NTRS)

1982-01-01

Capabilities of present passive systems are described and the development of passive remote sensing systems for the more abundant tropospheric trace species is recommended. The combination of nadir-viewing spectrometers and solar occultation for tropospheric measurement of those gases having large stratospheric burdens is discussed. Development of a nadir-viewing instrument capable of obtaining continuous spectra in narrower bands is recommended. Gas filter radiometers for species specific measurements and development of a spectral survey instrument are discussed. Further development of aerosol retrieval algorithms, including polarization techniques, for obtaining aerosol thickness and size distributions is advised. Recommendations of specific investigations to be pursued are presented.

A Wearable Real-Time and Non-Invasive Thoracic Cavity Monitoring System

NASA Astrophysics Data System (ADS)

Salman, Safa

A surgery-free on-body monitoring system is proposed to evaluate the dielectric constant of internal body tissues (especially lung and heart) and effectively determine irregularities in real-time. The proposed surgery-free on-body monitoring system includes a sensor, a post-processing technique, and an automated data collection circuit. Data are automatically collected from the sensor electrodes and then post processed to extract the electrical properties of the underlying biological tissue(s). To demonstrate the imaging concept, planar and wrap-around sensors are devised. These sensors are designed to detect changes in the dielectric constant of inner tissues (lung and heart). The planar sensor focuses on a single organ while the wrap-around sensors allows for imaging of the thoracic cavity's cross section. Moreover, post-processing techniques are proposed to complement sensors for a more complete on-body monitoring system. The idea behind the post-processing technique is to suppress interference from the outer layers (skin, fat, muscle, and bone). The sensors and post-processing techniques yield high signal (from the inner layers) to noise (from the outer layers) ratio. Additionally, data collection circuits are proposed for a more robust and stand-alone system. The circuit design aims to sequentially activate each port of the sensor and portions of the propagating signal are to be received at all passive ports in the form of a voltage at the probes. The voltages are converted to scattering parameters which are then used in the post-processing technique to obtain epsilonr. The concept of wearability is also considered through the use of electrically conductive fibers (E-fibers). These fibers show matching performance to that of copper, especially at low frequencies making them a viable substitute. For the cases considered, the proposed sensors show promising results in recovering the permittivity of deep tissues with a maximum error of 13.5%. These sensors provide a way for a new class of medical sensors through accuracy improvements and avoidance of inverse scattering techniques.

A new sensor system for accurate and precise determination of sediment dynamics and position.

NASA Astrophysics Data System (ADS)

Maniatis, Georgios; Hoey, Trevor; Sventek, Joseph; Hodge, Rebecca

2014-05-01

Sediment transport processes control many significant geomorphological changes. Consequently, sediment transport dynamics are studied across a wide range of scales leading to application of a variety of conceptually different mathematical descriptions (models) and data acquisition techniques (sensing). For river sediment transport processes both Eulerian and Lagrangian formulations are used. Data are gathered using a very wide range of sensing techniques that are not always compatible with the conceptual formulation applied. We are concerned with small to medium sediment grain-scale motion in gravel-bed rivers, and other coarse-grained environments, and: a) are developing a customised environmental sensor capable of providing coherent data that reliably record the motion; and, b) provide a mathematical framework in which these data can be analysed and interpreted, this being compatible with current stochastic approaches to sediment transport theory. Here we present results from three different aspects of the above developmental process. Firstly, we present a requirement analysis for the sensor based on the state of the art of the existing technologies. We focus on the factors that enhance data coherence and representativeness, extending the common practice for optimization which is based exclusively on electronics/computing related criteria. This analysis leads to formalization of a method that permits accurate control on the physical properties of the sensor using contemporary rapid prototyping techniques [Maniatis et al. 2013]. Secondly the first results are presented from a series of entrainment experiments in a 5 x 0.8 m flume in which a prototype sensor was deployed to monitor entrainment dynamics under increasing flow conditions (0.037 m3.s-1). The sensor was enclosed in an idealized spherical case (111 mm diameter) and placed on a constructed bed of hemispheres of the same diameter. We measured 3-axial inertial acceleration (as a measure of flow stress), with sampling frequency 4 to 10Hz, for two different initial positions over a range of slopes (from 0.026 to 0.57). The results reveal forces during the pre-entrainment phase and show the effect of slope on the temporal characteristics of the process. Finally we present results from the simulations using a mathematical framework developed to integrate the inertial-dynamics data (corresponding to the above experimental procedure and sensing conceptualization) [Abeywardana et al. 2012] with the mathematical techniques used in contemporary localization applications [Zanella et al. 2012]. We specifically assess different signal filtering techniques in terms of: a) how informative they are regarding the complexity of sediment movement; and, b) how possible it is to reduce rapidly accumulating errors that occur during sensing and increase positional accuracy. References Maniatis, G.; Hoey, T.; Sventek, J. Sensor Enclosures: Example Application and Implications for Data Coherence. J. Sens. Actuator Netw. 2013, 2, 761-779. Abeywardana, D. K., A. P. Hu, and N. Kularatna. "IPT charged wireless sensor module for river sedimentation detection." Sensors Applications Symposium (SAS), 2012 IEEE. IEEE, 2012. Zannella, Fillipo, and Angelo Cenedese. "Multi-agent tracking in wireless sensor networks: implementation." WSEAS Int. Conf. on Information Technology and Computer Networks (ITCN). 2012.

Long wave infrared cavity-enhanced sensors using quantum cascade lasers

NASA Astrophysics Data System (ADS)

Taubman, Matthew S.; Scott, David C.; Myers, Tanya L.; Cannon, Bret D.

2005-11-01

Quantum cascade lasers (QCLs) are becoming well known as convenient and stable semiconductor laser sources operating in the mid- to long-wave infrared, and are able to be fabricated to operate virtually anywhere in the 3.5 to 25 micron region. This makes them an ideal choice for infrared chemical sensing, a topic of great interest at present, spanning at least three critical areas: national security, environmental monitoring and protection, and the early diagnosis of disease through breath analysis. There are many different laser-based spectroscopic chemical sensor architectures in use today, from simple direct detection through to more complex and highly sensitive systems. Many current sensor needs can be met by combining QCLs and appropriate sensor architectures, those needs ranging from UAV-mounted surveillance systems, through to larger ultra-sensitive systems for airport security. In this paper we provide an overview of various laser-based spectroscopic sensing techniques, pointing out advantages and disadvantages of each. As part of this process, we include our own results and observations for techniques under development at PNNL. We also present the latest performance of our ultra-quiet QCL control electronics now being commercialized, and explore how using optimized supporting electronics enables increased sensor performance and decreased sensor footprint for given applications.

On-Line Flatness Measurement in the Steelmaking Industry

PubMed Central

Molleda, Julio; Usamentiaga, Rubén; Garcίa, Daniel F.

2013-01-01

Shape is a key characteristic to determine the quality of outgoing flat-rolled products in the steel industry. It is greatly influenced by flatness, a feature to describe how the surface of a rolled product approaches a plane. Flatness is of the utmost importance in steelmaking, since it is used by most downstream processes and customers for the acceptance or rejection of rolled products. Flatness sensors compute flatness measurements based on comparing the length of several longitudinal fibers of the surface of the product under inspection. Two main different approaches are commonly used. On the one hand, most mechanical sensors measure the tensile stress across the width of the rolled product, while manufacturing and estimating the fiber lengths from this stress. On the other hand, optical sensors measure the length of the fibers by means of light patterns projected onto the product surface. In this paper, we review the techniques and the main sensors used in the steelmaking industry to measure and quantify flatness defects in steel plates, sheets and strips. Most of these techniques and sensors can be used in other industries involving rolling mills or continuous production lines, such as aluminum, copper and paper, to name a few. Encompassed in the special issue, State-of-the-Art Sensors Technology in Spain 2013, this paper also reviews the most important flatness sensors designed and developed for the steelmaking industry in Spain. PMID:23939583

On-line flatness measurement in the steelmaking industry.

PubMed

Molleda, Julio; Usamentiaga, Rubén; García, Daniel F

2013-08-09

Shape is a key characteristic to determine the quality of outgoing flat-rolled products in the steel industry. It is greatly influenced by flatness, a feature to describe how the surface of a rolled product approaches a plane. Flatness is of the utmost importance in steelmaking, since it is used by most downstream processes and customers for the acceptance or rejection of rolled products. Flatness sensors compute flatness measurements based on comparing the length of several longitudinal fibers of the surface of the product under inspection. Two main different approaches are commonly used. On the one hand, most mechanical sensors measure the tensile stress across the width of the rolled product, while manufacturing and estimating the fiber lengths from this stress. On the other hand, optical sensors measure the length of the fibers by means of light patterns projected onto the product surface. In this paper, we review the techniques and the main sensors used in the steelmaking industry to measure and quantify flatness defects in steel plates, sheets and strips. Most of these techniques and sensors can be used in other industries involving rolling mills or continuous production lines, such as aluminum, copper and paper, to name a few. Encompassed in the special issue, State-of-the-Art Sensors Technology in Spain 2013, this paper also reviews the most important flatness sensors designed and developed for the steelmaking industry in Spain.

Shear Stress Sensing using Elastomer Micropillar Arrays

NASA Technical Reports Server (NTRS)

Wohl, Christopher J.; Palmieri, Frank L.; Lin, Yi; Jackson, Allen M.; Cissoto, Alexxandra; Sheplak, Mark; Connell, John W.

2013-01-01

The measurement of shear stress developed as a fluid moves around a solid body is difficult to measure. Stresses at the fluid-solid interface are very small and the nature of the fluid flow is easily disturbed by introducing sensor components to the interface. To address these challenges, an array of direct and indirect techniques have been investigated with various advantages and challenges. Hot wire sensors and other indirect sensors all protrude significantly into the fluid flow. Microelectromechanical systems (MEMS) devices, although facilitating very accurate measurements, are not durable, are prone to contamination, and are difficult to implement into existing model geometries. One promising approach is the use of engineered surfaces that interact with fluid flow in a detectable manner. To this end, standard lithographic techniques have been utilized to generate elastomeric micropillar arrays of various lengths and diameters. Micropillars of controlled length and width were generated in polydimethylsiloxane (PDMS) elastomer using a soft-lithography technique. The 3D mold for micropillar replication was fabricated using laser ablative micromachining and contact lithography. Micropillar dimensions and mechanical properties were characterized and compared to shear sensing requirements. The results of this characterization as well as shear stress detection techniques will be discussed.

Surface Plasmon Resonance-Based Fiber Optic Sensors Utilizing Molecular Imprinting

PubMed Central

Gupta, Banshi D.; Shrivastav, Anand M.; Usha, Sruthi P.

2016-01-01

Molecular imprinting is earning worldwide attention from researchers in the field of sensing and diagnostic applications, due to its properties of inevitable specific affinity for the template molecule. The fabrication of complementary template imprints allows this technique to achieve high selectivity for the analyte to be sensed. Sensors incorporating this technique along with surface plasmon or localized surface plasmon resonance (SPR/LSPR) provide highly sensitive real time detection with quick response times. Unfolding these techniques with optical fiber provide the additional advantages of miniaturized probes with ease of handling, online monitoring and remote sensing. In this review a summary of optical fiber sensors using the combined approaches of molecularly imprinted polymer (MIP) and the SPR/LSPR technique is discussed. An overview of the fundamentals of SPR/LSPR implementation on optical fiber is provided. The review also covers the molecular imprinting technology (MIT) with its elementary study, synthesis procedures and its applications for chemical and biological anlayte detection with different sensing methods. In conclusion, we explore the advantages, challenges and the future perspectives of developing highly sensitive and selective methods for the detection of analytes utilizing MIT with the SPR/LSPR phenomenon on optical fiber platforms. PMID:27589746

Fatigue crack monitoring with coupled piezoelectric film acoustic emission sensors

NASA Astrophysics Data System (ADS)

Zhou, Changjiang

Fatigue-induced cracking is a commonly seen problem in civil infrastructures reaching their original design life. A number of high-profile accidents have been reported in the past that involved fatigue damage in structures. Such incidences often happen without prior warnings due to lack of proper crack monitoring technique. In order to detect and monitor the fatigue crack, acoustic emission (AE) technique, has been receiving growing interests recently. AE can provide continuous and real-time monitoring data on damage progression in structures. Piezoelectric film AE sensor measures stress-wave induced strain in ultrasonic frequency range and its feasibility for AE signal monitoring has been demonstrated recently. However, extensive work in AE monitoring system development based on piezoelectric film AE sensor and sensor characterization on full-scale structures with fatigue cracks, have not been done. A lack of theoretical formulations for understanding the AE signals also hinders the use of piezoelectric film AE sensors. Additionally, crack detection and source localization with AE signals is a very important area yet to be explored for this new type of AE sensor. This dissertation presents the results of both analytical and experimental study on the signal characteristics of surface stress-wave induced AE strain signals measured by piezoelectric film AE sensors in near-field and an AE source localization method based on sensor couple theory. Based on moment tensor theory, generalized expression for AE strain signal is formulated. A special case involving the response of piezoelectric film AE sensor to surface load is also studied, which could potentially be used for sensor calibration of this type of sensor. A new concept of sensor couple theory based AE source localization technique is proposed and validated with both simulated and experimental data from fatigue test and field monitoring. Two series of fatigue tests were conducted to perform fatigue crack monitoring on large-scale steel test specimens using piezoelectric film AE sensors. Continuous monitoring of fatigue crack growth in steel structures is demonstrated in these fatigue test specimens. The use of piezoelectric film AE sensor for field monitoring of existing fatigue crack is also demonstrated in a real steel I-girder bridge located in Maryland. The sensor couple theory based AE source localization is validated using a limited number of piezoelectric film AE sensor data from both fatigue test specimens and field monitoring bridge. Through both laboratory fatigue test and field monitoring of steel structures with active fatigue cracks, the signal characteristics of piezoelectric film AE sensor have been studied in real-world environment.

Nondestructive surface analysis for material research using fiber optic vibrational spectroscopy

NASA Astrophysics Data System (ADS)

Afanasyeva, Natalia I.

2001-11-01

The advanced methods of fiber optical vibrational spectroscopy (FOVS) has been developed in conjunction with interferometer and low-loss, flexible, and nontoxic optical fibers, sensors, and probes. The combination of optical fibers and sensors with Fourier Transform (FT) spectrometer has been used in the range from 2.5 to 12micrometers . This technique serves as an ideal diagnostic tool for surface analysis of numerous and various diverse materials such as complex structured materials, fluids, coatings, implants, living cells, plants, and tissue. Such surfaces as well as living tissue or plants are very difficult to investigate in vivo by traditional FT infrared or Raman spectroscopy methods. The FOVS technique is nondestructive, noninvasive, fast (15 sec) and capable of operating in remote sampling regime (up to a fiber length of 3m). Fourier transform infrared (FTIR) and Raman fiber optic spectroscopy operating with optical fibers has been suggested as a new powerful tool. These techniques are highly sensitive techniques for structural studies in material research and various applications during process analysis to determine molecular composition, chemical bonds, and molecular conformations. These techniques could be developed as a new tool for quality control of numerous materials as well as noninvasive biopsy.

Fiber-Optic Continuous Liquid Sensor for Cryogenic Propellant Gauging

NASA Technical Reports Server (NTRS)

Xu. Wei

2010-01-01

An innovative fiber-optic sensor has been developed for low-thrust-level settled mass gauging with measurement uncertainty <0.5 percent over cryogenic propellant tank fill levels from 2 to 98 percent. The proposed sensor uses a single optical fiber to measure liquid level and liquid distribution of cryogenic propellants. Every point of the sensing fiber is a point sensor that not only distinguishes liquid and vapor, but also measures temperature. This sensor is able to determine the physical location of each point sensor with 1-mm spatial resolution. Acting as a continuous array of numerous liquid/vapor point sensors, the truly distributed optical sensing fiber can be installed in a propellant tank in the same manner as silicon diode point sensor stripes using only a single feedthrough to connect to an optical signal interrogation unit outside the tank. Either water or liquid nitrogen levels can be measured within 1-mm spatial resolution up to a distance of 70 meters from the optical interrogation unit. This liquid-level sensing technique was also compared to the pressure gauge measurement technique in water and liquid nitrogen contained in a vertical copper pipe with a reasonable degree of accuracy. It has been demonstrated that the sensor can measure liquid levels in multiple containers containing water or liquid nitrogen with one signal interrogation unit. The liquid levels measured by the multiple fiber sensors were consistent with those virtually measured by a ruler. The sensing performance of various optical fibers has been measured, and has demonstrated that they can survive after immersion at cryogenic temperatures. The fiber strength in liquid nitrogen has also been measured. Multiple water level tests were also conducted under various actual and theoretical vibration conditions, and demonstrated that the signal-to-noise ratio under these vibration conditions, insofar as it affects measurement accuracy, is manageable and robust enough for a wide variety of spacecraft applications. A simple solution has been developed to absorb optical energy at the termination of the optical sensor, thereby avoiding any feedback to the optical interrogation unit

A Human Serum-Based Enzyme-Free Continuous Glucose Monitoring Technique Using a Needle-Type Bio-Layer Interference Sensor.

PubMed

Seo, Dongmin; Paek, Sung-Ho; Oh, Sangwoo; Seo, Sungkyu; Paek, Se-Hwan

2016-09-24

The incidence of diabetes is continually increasing, and by 2030, it is expected to have increased by 69% and 20% in underdeveloped and developed countries, respectively. Therefore, glucose sensors are likely to remain in high demand in medical device markets. For the current study, we developed a needle-type bio-layer interference (BLI) sensor that can continuously monitor glucose levels. Using dialysis procedures, we were able to obtain hypoglycemic samples from commercial human serum. These dialysis-derived samples, alongside samples of normal human serum were used to evaluate the utility of the sensor for the detection of the clinical interest range of glucose concentrations (70-200 mg/dL), revealing high system performance for a wide glycemic state range (45-500 mg/dL). Reversibility and reproducibility were also tested over a range of time spans. Combined with existing BLI system technology, this sensor holds great promise for use as a wearable online continuous glucose monitoring system for patients in a hospital setting.

Coordinating standards and applications for optical water quality sensor networks

USGS Publications Warehouse

Bergamaschi, B.; Pellerin, B.

2011-01-01

Joint USGS-CUAHSI Workshop: In Situ Optical Water Quality Sensor Networks; Shepherdstown, West Virginia, 8-10 June 2011; Advanced in situ optical water quality sensors and new techniques for data analysis hold enormous promise for advancing scientific understanding of aquatic systems through measurements of important biogeochemical parameters at the time scales over which they vary. High-frequency and real-time water quality data also provide the opportunity for early warning of water quality deterioration, trend detection, and science-based decision support. However, developing networks of optical sensors in freshwater systems that report reliable and comparable data across and between sites remains a challenge to the research and monitoring community. To address this, the U.S. Geological Survey (USGS) and the Consortium of Universities for the Advancement of Hydrologic Science, Inc. (CUAHSI), convened a 3-day workshop to explore ways to coordinate development of standards and applications for optical sensors, as well as handling, storage, and analysis of the continuous data they produce.

NASA Programs in Advanced Sensors and Measurement Technology for Aeronautical Applications

NASA Technical Reports Server (NTRS)

Conway, Bruce A.

2004-01-01

There are many challenges facing designers and operators of our next-generation aircraft in meeting the demands for efficiency, safety, and reliability which are will be imposed. This paper discusses aeronautical sensor requirements for a number of research and applications areas pertinent to the demands listed above. A brief overview will be given of aeronautical research measurements, along with a discussion of requirements for advanced technology. Also included will be descriptions of emerging sensors and instrumentation technology which may be exploited for enhanced research and operational capabilities. Finally, renewed emphasis of the National Aeronautics and Space Administration in advanced sensor and instrumentation technology development will be discussed, including project of technology advances over the next 5 years. Emphasis on NASA efforts to more actively advance the state-of-the-art in sensors and measurement techniques is timely in light of exciting new opportunities in airspace development and operation. An up-to-date summary of the measurement technology programs being established to respond to these opportunities is provided.

Solution-gated graphene transistors for chemical and biological sensors.

PubMed

Yan, Feng; Zhang, Meng; Li, Jinhua

2014-03-01

Graphene has attracted much attention in biomedical applications for its fascinating properties. Because of the well-known 2D structure, every atom of graphene is exposed to the environment, so the electronic properties of graphene are very sensitive to charged analytes (ions, DNA, cells, etc.) or an electric field around it, which renders graphene an ideal material for high-performance sensors. Solution-gated graphene transistors (SGGTs) can operate in electrolytes and are thus excellent candidates for chemical and biological sensors, which have been extensively studied in the recent 5 years. Here, the device physics, the sensing mechanisms, and the performance of the recently developed SGGT-based chemical and biological sensors, including pH, ion, cell, bacterial, DNA, protein, glucose sensors, etc., are introduced. Their advantages and shortcomings, in comparison with some conventional techniques, are discussed. Conclusions and challenges for the future development of the field are addressed in the end. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemical preparation of graphene-based nanomaterials and their applications in chemical and biological sensors.

PubMed

Jiang, Hongji

2011-09-05

Graphene is a flat monolayer of carbon atoms packed tightly into a 2D honeycomb lattice that shows many intriguing properties meeting the key requirements for the implementation of highly excellent sensors, and all kinds of proof-of-concept sensors have been devised. To realize the potential sensor applications, the key is to synthesize graphene in a controlled way to achieve enhanced solution-processing capabilities, and at the same time to maintain or even improve the intrinsic properties of graphene. Several production techniques for graphene-based nanomaterials have been developed, ranging from the mechanical cleavage and chemical exfoliation of high-quality graphene to direct growth onto different substrates and the chemical routes using graphite oxide as a precusor to the newly developed bottom-up approach at the molecular level. The current review critically explores the recent progress on the chemical preparation of graphene-based nanomaterials and their applications in sensors. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An adaptive technique for a redundant-sensor navigation system.

NASA Technical Reports Server (NTRS)

Chien, T.-T.

1972-01-01

An on-line adaptive technique is developed to provide a self-contained redundant-sensor navigation system with a capability to utilize its full potentiality in reliability and performance. This adaptive system is structured as a multistage stochastic process of detection, identification, and compensation. It is shown that the detection system can be effectively constructed on the basis of a design value, specified by mission requirements, of the unknown parameter in the actual system, and of a degradation mode in the form of a constant bias jump. A suboptimal detection system on the basis of Wald's sequential analysis is developed using the concept of information value and information feedback. The developed system is easily implemented, and demonstrates a performance remarkably close to that of the optimal nonlinear detection system. An invariant transformation is derived to eliminate the effect of nuisance parameters such that the ambiguous identification system can be reduced to a set of disjoint simple hypotheses tests. By application of a technique of decoupled bias estimation in the compensation system the adaptive system can be operated without any complicated reorganization.

Progress toward a cosmic dust collection facility on space station

NASA Technical Reports Server (NTRS)

Mackinnon, Ian D. R. (Editor); Carey, William C. (Editor)

1987-01-01

Scientific and programmatic progress toward the development of a cosmic dust collection facility (CDCF) for the proposed space station is documented. Topics addressed include: trajectory sensor concepts; trajectory accuracy and orbital evolution; CDCF pointing direction; development of capture devices; analytical techniques; programmatic progress; flight opportunities; and facility development.

High-Temperature Optical Sensor

NASA Technical Reports Server (NTRS)

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

2010-01-01

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

Using Smartphone Sensors for Improving Energy Expenditure Estimation

PubMed Central

Zhu, Jindan; Das, Aveek K.; Zeng, Yunze; Mohapatra, Prasant; Han, Jay J.

2015-01-01

Energy expenditure (EE) estimation is an important factor in tracking personal activity and preventing chronic diseases, such as obesity and diabetes. Accurate and real-time EE estimation utilizing small wearable sensors is a difficult task, primarily because the most existing schemes work offline or use heuristics. In this paper, we focus on accurate EE estimation for tracking ambulatory activities (walking, standing, climbing upstairs, or downstairs) of a typical smartphone user. We used built-in smartphone sensors (accelerometer and barometer sensor), sampled at low frequency, to accurately estimate EE. Using a barometer sensor, in addition to an accelerometer sensor, greatly increases the accuracy of EE estimation. Using bagged regression trees, a machine learning technique, we developed a generic regression model for EE estimation that yields upto 96% correlation with actual EE. We compare our results against the state-of-the-art calorimetry equations and consumer electronics devices (Fitbit and Nike+ FuelBand). The newly developed EE estimation algorithm demonstrated superior accuracy compared with currently available methods. The results were calibrated against COSMED K4b2 calorimeter readings. PMID:27170901

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.

Using Smartphone Sensors for Improving Energy Expenditure Estimation.

PubMed

Pande, Amit; Zhu, Jindan; Das, Aveek K; Zeng, Yunze; Mohapatra, Prasant; Han, Jay J

2015-01-01

Energy expenditure (EE) estimation is an important factor in tracking personal activity and preventing chronic diseases, such as obesity and diabetes. Accurate and real-time EE estimation utilizing small wearable sensors is a difficult task, primarily because the most existing schemes work offline or use heuristics. In this paper, we focus on accurate EE estimation for tracking ambulatory activities (walking, standing, climbing upstairs, or downstairs) of a typical smartphone user. We used built-in smartphone sensors (accelerometer and barometer sensor), sampled at low frequency, to accurately estimate EE. Using a barometer sensor, in addition to an accelerometer sensor, greatly increases the accuracy of EE estimation. Using bagged regression trees, a machine learning technique, we developed a generic regression model for EE estimation that yields upto 96% correlation with actual EE. We compare our results against the state-of-the-art calorimetry equations and consumer electronics devices (Fitbit and Nike+ FuelBand). The newly developed EE estimation algorithm demonstrated superior accuracy compared with currently available methods. The results were calibrated against COSMED K4b2 calorimeter readings.

High Density Metamaterials for Visible Light

DTIC Science & Technology

2016-11-28

gold first and then extend the techniques to other metals for better characteristics. Bio -chemical sensors will be developed based on different split...metamaterials for Bio -chemical sensing. Using our sonicated cold development electron beam lithography process that has recently been shown to overcome

Recent Developments in Microsystems Fabricated by the Liga-Technique

NASA Technical Reports Server (NTRS)

Schulz, J.; Bade, K.; El-Kholi, A.; Hein, H.; Mohr, J.

1995-01-01

As an example of microsystems fabricated by the LIGA-technique (x-ray lithography, electroplating and molding), three systems are described and characterized: a triaxial acceleration sensor system, a micro-optical switch, and a microsystem for the analysis of pollutants. The fabrication technologies are reviewed with respect to the key components of the three systems: an acceleration sensor, and electrostatic actuator, and a spectrometer made by the LIGA-technique. Aa micro-pump and micro-valve made by using micromachined tools for molding and optical fiber imaging are made possible by combining LIGA and anisotropic etching of silicon in a batch process. These examples show that the combination of technologies and components is the key to complex microsystems. The design of such microsystems will be facilitated is standardized interfaces are available.

Damage Evaluation Based on a Wave Energy Flow Map Using Multiple PZT Sensors

PubMed Central

Liu, Yaolu; Hu, Ning; Xu, Hong; Yuan, Weifeng; Yan, Cheng; Li, Yuan; Goda, Riu; Alamusi; Qiu, Jinhao; Ning, Huiming; Wu, Liangke

2014-01-01

A new wave energy flow (WEF) map concept was proposed in this work. Based on it, an improved technique incorporating the laser scanning method and Betti's reciprocal theorem was developed to evaluate the shape and size of damage as well as to realize visualization of wave propagation. In this technique, a simple signal processing algorithm was proposed to construct the WEF map when waves propagate through an inspection region, and multiple lead zirconate titanate (PZT) sensors were employed to improve inspection reliability. Various damages in aluminum and carbon fiber reinforced plastic laminated plates were experimentally and numerically evaluated to validate this technique. The results show that it can effectively evaluate the shape and size of damage from wave field variations around the damage in the WEF map. PMID:24463430

Techniques for Sea Ice Characteristics Extraction and Sea Ice Monitoring Using Multi-Sensor Satellite Data in the Bohai Sea-Dragon 3 Programme Final Report (2012-2016)

NASA Astrophysics Data System (ADS)

Zhang, Xi; Zhang, Jie; Meng, Junmin

2016-08-01

The objectives of Dragon-3 programme (ID: 10501) are to develop methods for classification sea ice types and retrieving ice thickness based on multi-sensor data. In this final results paper, we give a briefly introduction for our research work and mainly results. Key words: the Bohai Sea ice, Sea ice, optical and

Measurement of splanchnic photoplethysmographic signals using a new reflectance fiber optic sensor

NASA Astrophysics Data System (ADS)

Hickey, Michelle; Samuels, Neal; Randive, Nilesh; Langford, Richard M.; Kyriacou, Panayiotis A.

2010-03-01

Splanchnic organs are particularly vulnerable to hypoperfusion. Currently, there is no technique that allows for the continuous estimation of splanchnic blood oxygen saturation (SpO2). As a preliminary to developing a suitable splanchnic SpO2 sensor, a new reflectance fiber optic photoplethysmographic (PPG) sensor and processing system are developed. An experimental procedure to examine the effect of fiber source detector separation distance on acquired PPG signals is carried out before finalizing the sensor design. PPG signals are acquired from four volunteers for separation distances of 1 to 8 mm. The separation range of 3 to 6 mm provides the best quality PPG signals with large amplitudes and the highest signal-to-noise ratios (SNRs). Preliminary calculation of SpO2 shows that distances of 3 and 4 mm provide the most realistic values. Therefore, it is suggested that the separation distance in the design of a fiber optic reflectance pulse oximeter be in the range of 3 to 4 mm. Preliminary PPG signals from various splanchnic organs and the periphery are obtained from six anaesthetized patients. The normalized amplitudes of the splanchnic PPGs are, on average, approximately the same as those obtained simultaneously from the periphery. These observations suggest that fiber optic pulse oximetry may be a valid monitoring technique for splanchnic organs.

Disposable microfluidic sensor arrays for discrimination of antioxidants.

PubMed

Park, Seong H; Maruniak, Autumn; Kim, Jisun; Yi, Gi-Ra; Lim, Sung H

2016-06-01

A microfluidic colorimetric sensor array was developed for detection and identification of various antioxidants. The sensor was fabricated by a photolithographic method, and consists of an array of printed cross-responsive indicators. The microfluidic design also incorporates pre-activation spots to allow printing of chemically incompatible components separately. Separately printed oxidizer allowed an oxidation of adjacent redox indicators only when aqueous sample was added to the sensor cartridge. Antioxidants were primarily detected by measuring the extent of inhibition of this oxidation reaction. Using this flow-based technique, a clear differentiation of 8 different antioxidants and 4 different teas has been demonstrated with 98.5% sensitivity. Copyright © 2016 Elsevier B.V. All rights reserved.

“Playing around” with Field-Effect Sensors on the Basis of EIS Structures, LAPS and ISFETs

PubMed Central

Schöning, Michael J.

2005-01-01

Microfabricated semiconductor devices are becoming increasingly relevant, also for the detection of biological and chemical quantities. Especially, the “marriage” of biomolecules and silicon technology often yields successful new sensor concepts. The fabrication techniques of such silicon-based chemical sensors and biosensors, respectively, will have a distinct impact in different fields of application such as medicine, food technology, environment, chemistry and biotechnology as well as information processing. Moreover, scientists and engineers are interested in the analytical benefits of miniaturised and microfabricated sensor devices. This paper gives a survey on different types of semiconductor-based field-effect structures that have been recently developed in our laboratory.

Expanding the Capabilities of the JPL Electronic Nose for an International Space Station Technology Demonstration

NASA Technical Reports Server (NTRS)

Ryan, Margaret A.; Shevade, A. V.; Taylor, C. J.; Homer, M. L.; Jewell, A. D.; Kisor, A.; Manatt, K. S .; Yen, S. P. S.; Blanco, M.; Goddard, W. A., III

2006-01-01

An array-based sensing system based on polymer/carbon composite conductometric sensors is under development at JPL for use as an environmental monitor in the International Space Station. Sulfur dioxide has been added to the analyte set for this phase of development. Using molecular modeling techniques, the interaction energy between SO2 and polymer functional groups has been calculated, and polymers selected as potential SO2 sensors. Experiment has validated the model and two selected polymers have been shown to be promising materials for SO2 detection.

A Low-Cost Inkjet-Printed Aptamer-Based Electrochemical Biosensor for the Selective Detection of Lysozyme.

PubMed

Khan, Niazul Islam; Maddaus, Alec G; Song, Edward

2018-01-15

Recently, inkjet-printing has gained increased popularity in applications such as flexible electronics and disposable sensors, as well as in wearable sensors because of its multifarious advantages. This work presents a novel, low-cost immobilization technique using inkjet-printing for the development of an aptamer-based biosensor for the detection of lysozyme, an important biomarker in various disease diagnosis. The strong affinity between the carbon nanotube (CNT) and the single-stranded DNA is exploited to immobilize the aptamers onto the working electrode by printing the ink containing the dispersion of CNT-aptamer complex. The inkjet-printing method enables aptamer density control, as well as high resolution patternability. Our developed sensor shows a detection limit of 90 ng/mL with high target selectivity against other proteins. The sensor also demonstrates a shelf-life for a reasonable period. This technology has potential for applications in developing low-cost point-of-care diagnostic testing kits for home healthcare.

A wearable pressure sensor based on ultra-violet/ozone microstructured carbon nanotube/polydimethylsiloxane arrays for electronic skins.

PubMed

Yu, Guohui; Hu, Jingdong; Tan, Jianping; Gao, Yang; Lu, Yongfeng; Xuan, Fuzhen

2018-03-16

Pressure sensors with high performance (e.g., a broad pressure sensing range, high sensitivities, rapid response/relaxation speeds, temperature-stable sensing), as well as a cost-effective and highly efficient fabrication method are highly desired for electronic skins. In this research, a high-performance pressure sensor based on microstructured carbon nanotube/polydimethylsiloxane arrays was fabricated using an ultra-violet/ozone (UV/O 3 ) microengineering technique. The UV/O 3 microengineering technique is controllable, cost-effective, and highly efficient since it is conducted at room temperature in an ambient environment. The pressure sensor offers a broad pressure sensing range (7 Pa-50 kPa), a sensitivity of ∼ -0.101 ± 0.005 kPa -1 (<1 kPa), a fast response/relaxation speed of ∼10 ms, a small dependence on temperature variation, and a good cycling stability (>5000 cycles), which is attributed to the UV/O 3 engineered microstructures that amplify and transfer external applied forces and rapidly store/release the energy during the PDMS deformation. The sensors developed show the capability to detect external forces and monitor human health conditions, promising for the potential applications in electronic skin.

Nanostructure Engineered Chemical Sensors for Hazardous Gas and Vapor Detection

NASA Technical Reports Server (NTRS)

Li, Jing; Lu, Yijiang

2005-01-01

A nanosensor technology has been developed using nanostructures, such as single walled carbon nanotubes (SWNTs) and metal oxides nanowires or nanobelts, on a pair of interdigitated electrodes (IDE) processed with a silicon based microfabrication and micromachining technique. The IDE fingers were fabricated using thin film metallization techniques. Both in-situ growth of nanostructure materials and casting of the nanostructure dispersions were used to make chemical sensing devices. These sensors have been exposed to hazardous gases and vapors, such as acetone, benzene, chlorine, and ammonia in the concentration range of ppm to ppb at room temperature. The electronic molecular sensing in our sensor platform can be understood by electron modulation between the nanostructure engineered device and gas molecules. As a result of the electron modulation, the conductance of nanodevice will change. Due to the large surface area, low surface energy barrier and high thermal and mechanical stability, nanostructured chemical sensors potentially can offer higher sensitivity, lower power consumption and better robustness than the state-of-the-art systems, which make them more attractive for defense and space applications. Combined with MEMS technology, light weight and compact size sensors can be made in wafer scale with low cost.

A wearable pressure sensor based on ultra-violet/ozone microstructured carbon nanotube/polydimethylsiloxane arrays for electronic skins

NASA Astrophysics Data System (ADS)

Yu, Guohui; Hu, Jingdong; Tan, Jianping; Gao, Yang; Lu, Yongfeng; Xuan, Fuzhen

2018-03-01

Pressure sensors with high performance (e.g., a broad pressure sensing range, high sensitivities, rapid response/relaxation speeds, temperature-stable sensing), as well as a cost-effective and highly efficient fabrication method are highly desired for electronic skins. In this research, a high-performance pressure sensor based on microstructured carbon nanotube/polydimethylsiloxane arrays was fabricated using an ultra-violet/ozone (UV/O3) microengineering technique. The UV/O3 microengineering technique is controllable, cost-effective, and highly efficient since it is conducted at room temperature in an ambient environment. The pressure sensor offers a broad pressure sensing range (7 Pa-50 kPa), a sensitivity of ˜ -0.101 ± 0.005 kPa-1 (<1 kPa), a fast response/relaxation speed of ˜10 ms, a small dependence on temperature variation, and a good cycling stability (>5000 cycles), which is attributed to the UV/O3 engineered microstructures that amplify and transfer external applied forces and rapidly store/release the energy during the PDMS deformation. The sensors developed show the capability to detect external forces and monitor human health conditions, promising for the potential applications in electronic skin.

Got Point Clouds: Characterizing Canopy Structure With Active and Passive Sensors

NASA Astrophysics Data System (ADS)

Popescu, S. C.; Malambo, L.; Sheridan, R.; Putman, E.; Murray, S.; Rooney, W.; Rajan, N.

2016-12-01

Unmanned Aerial Systems (UAS) provide the means to acquire highly customized aerial data at local scale with a multitude of sensors. UAS allow us to obtain affordably repeated observations of canopy structure for agricultural and natural resources applications by using passive optical sensors, such as cameras and photogrammetric techniques, and active sensors, such as lidar (Light Detection and Ranging). The objectives of this presentation are to: (1) offer a brief overview of UAS used for agriculture and natural resources studies, (2) describe experiences in conducting agriculture phenotyping and forest vegetation measurements, and (3) give details on the methodology developed for image and lidar data processing for characterizing the three dimensional structure of plant canopies. The UAS types used for this purpose included rotary platforms, such as quadcopters, hexacopters, and octocopters, with a payload capacity of up to 19 lbs. The sensors that collected data over two crop seasons include multispectral cameras in the visible color spectrum and near infrared, and UAS-lidar. For ground reference data we used terrestrial lidar scanners and field measurements. Results comparing UAS and terrestrial measurements show high correlation and open new areas of scientific investigation of crop canopies previously not possible with affordable techniques.

The Early Development of Satellite Characterization Capabilities at the Air Force Laboratories

NASA Astrophysics Data System (ADS)

Lambert, J.; Kissell, K.

This presentation overviews the development of optical Space Object Identification (SOI) techniques at the Air Force laboratories during the two-decade "pre-operational" period prior to 1980 when the Groundbased Electro-Optical Deep Space Surveillance (GEODSS) sensors were deployed. Beginning with the launch of Sputnik in 1957, the United States Air Force has actively pursued the development and application of optical sensor technology for the detection, tracking, and characterization of artificial satellites. Until the mid-1980s, these activities were primarily conducted within Air Force research and development laboratories which supplied data to the operational components on a contributing basis. This presentation traces the early evolution of the optical space surveillance technologies from the early experimental sensors that led to the current generation of operationally deployed and research systems. The contributions of the participating Air Force organizations and facilities will be reviewed with special emphasis on the development of technologies for the characterization of spacecraft using optical signatures and imagery. The presentation will include descriptions and photographs of the early facilities and instrumentation, and examples of the SOI collection and analysis techniques employed. In this early period, computer support was limited so all aspects of space surveillance relied heavily on manual interaction. Many military, government, educational, and contractor agencies supported the development of instrumentation and analysis techniques. This overview focuses mainly on the role played by Air Force System Command and Office of Aerospace Research, and the closely related activities at the Department of Defense Advanced Research Projects Agency. The omission of other agencies from this review reflects the limitations of this presentation, not the significance of their contributions.

Localization of Ferromagnetic Target with Three Magnetic Sensors in the Movement Considering Angular Rotation

PubMed Central

Gao, Xiang; Yan, Shenggang; Li, Bin

2017-01-01

Magnetic detection techniques have been widely used in many fields, such as virtual reality, surgical robotics systems, and so on. A large number of methods have been developed to obtain the position of a ferromagnetic target. However, the angular rotation of the target relative to the sensor is rarely studied. In this paper, a new method for localization of moving object to determine both the position and rotation angle with three magnetic sensors is proposed. Trajectory localization estimation of three magnetic sensors, which are collinear and noncollinear, were obtained by the simulations, and experimental results demonstrated that the position and rotation angle of ferromagnetic target having roll, pitch or yaw in its movement could be calculated accurately and effectively with three noncollinear vector sensors. PMID:28892006

Suppression of span in sealed microcavity Fabry-Perot pressure sensors

NASA Astrophysics Data System (ADS)

Mishra, Shivam; Rajappa, Balasubramaniam; Chandra, Sudhir

2017-01-01

Optical microelectromechanical system pressure sensors working on the principle of extrinsic Fabry-Perot (FP) interferometer are designed and fabricated for pressure range of 1-bar absolute. Anodic bonding of silicon with glass is performed under atmospheric pressure to form FP cavity. This process results in entrapment of gas in the sealed microcavity. The effect of trapped gas is investigated on sensor characteristics. A closed-loop solution is derived for the deflection of the diaphragm of a sealed microcavity pressure sensor. Phenomenon of "suppression of span" is brought out. The sensors are tested using white light interferometry technique. The residual pressure of the trapped gas is estimated from the experiments. The developed model has been used to estimate the deflection sensitivity of the free diaphragm and the extent of suppression of span after bonding.

A Novel Wearable Electronic Nose for Healthcare Based on Flexible Printed Chemical Sensor Array

PubMed Central

Lorwongtragool, Panida; Sowade, Enrico; Watthanawisuth, Natthapol; Baumann, Reinhard R.; Kerdcharoen, Teerakiat

2014-01-01

A novel wearable electronic nose for armpit odor analysis is proposed by using a low-cost chemical sensor array integrated in a ZigBee wireless communication system. We report the development of a carbon nanotubes (CNTs)/polymer sensor array based on inkjet printing technology. With this technique both composite-like layer and actual composite film of CNTs/polymer were prepared as sensing layers for the chemical sensor array. The sensor array can response to a variety of complex odors and is installed in a prototype of wearable e-nose for monitoring the axillary odor released from human body. The wearable e-nose allows the classification of different armpit odors and the amount of the volatiles released as a function of level of skin hygiene upon different activities. PMID:25340447

Smart Sensors: Why and when the origin was and why and where the future will be

NASA Astrophysics Data System (ADS)

Corsi, C.

2013-12-01

Smart Sensors is a technique developed in the 70's when the processing capabilities, based on readout integrated with signal processing, was still far from the complexity needed in advanced IR surveillance and warning systems, because of the enormous amount of noise/unwanted signals emitted by operating scenario especially in military applications. The Smart Sensors technology was kept restricted within a close military environment exploding in applications and performances in the 90's years thanks to the impressive improvements in the integrated signal read-out and processing achieved by CCD-CMOS technologies in FPA. In fact the rapid advances of "very large scale integration" (VLSI) processor technology and mosaic EO detector array technology allowed to develop new generations of Smart Sensors with much improved signal processing by integrating microcomputers and other VLSI signal processors. inside the sensor structure achieving some basic functions of living eyes (dynamic stare, non-uniformity compensation, spatial and temporal filtering). New and future technologies (Nanotechnology, Bio-Organic Electronics, Bio-Computing) are lightning a new generation of Smart Sensors extending the Smartness from the Space-Time Domain to Spectroscopic Functional Multi-Domain Signal Processing. History and future forecasting of Smart Sensors will be reported.

Development of an underwater in-situ spectrophotometric sensor for seawater pH

NASA Astrophysics Data System (ADS)

Waterbury, Robert D.; Byrne, Robert H.; Kelly, John; Leader, Bram; McElligott, Sean; Russell, Randy

1996-12-01

A pH sensor based upon spectrophotometric techniques has been developed for in-situ analysis of surface seawater. This sensor utilizes a spectrophotometric pH indicator (Thymol Blue) which has been calibrated for use in seawater as a function of temperature and salinity. Shipboard spectrophotometric pH analyses routinely demonstrate a precision on the order of plus or minus 0.0004 pH units. In- situ analysis of seawater pH has demonstrated a precision on the order of plus or minus 0.001 and an accuracy, using shipboard measurements as a standard, on the order of plus or minus 0.01. The sensor is a self-contained system which pumps seawater, meters in indicator, spectrophotometrically determines indicator absorbance and stores data with a 1 Hz acquisition frequency. The sensor employs two absorbance cells, each with three wavelength channels, to obtain the spectrophotometric absorbance. The sensor system, rated for depths up to 500 m, provides pH, conductivity, temperature and can be operated via computer or in a standalone mode with internal data storage. The sensor utilizes less than 12 watts of power and is packaged in a 29' long by 4.5' diameter aluminum housing.

A low-power integrated humidity CMOS sensor by printing-on-chip technology.

PubMed

Lee, Chang-Hung; Chuang, Wen-Yu; Cowan, Melissa A; Wu, Wen-Jung; Lin, Chih-Ting

2014-05-23

A low-power, wide-dynamic-range integrated humidity sensing chip is implemented using a printable polymer sensing material with an on-chip pulse-width-modulation interface circuit. By using the inkjet printing technique, poly(3,4-ethylene-dioxythiophene)/polystyrene sulfonate that has humidity sensing features can be printed onto the top metal layer of a 0.35 μm CMOS IC. The developed printing-on-chip humidity sensor achieves a heterogeneous three dimensional sensor system-on-chip architecture. The humidity sensing of the implemented printing-on-chip sensor system is experimentally tested. The sensor shows a sensitivity of 0.98% to humidity in the atmosphere. The maximum dynamic range of the readout circuit is 9.8 MΩ, which can be further tuned by the frequency of input signal to fit the requirement of the resistance of printed sensor. The power consumption keeps only 154 μW. This printing-on-chip sensor provides a practical solution to fulfill an ultra-small integrated sensor for the applications in miniaturized sensing systems.

A Low-Power Integrated Humidity CMOS Sensor by Printing-on-Chip Technology

PubMed Central

Lee, Chang-Hung; Chuang, Wen-Yu; Cowan, Melissa A.; Wu, Wen-Jung; Lin, Chih-Ting

2014-01-01

A low-power, wide-dynamic-range integrated humidity sensing chip is implemented using a printable polymer sensing material with an on-chip pulse-width-modulation interface circuit. By using the inkjet printing technique, poly(3,4-ethylene-dioxythiophene)/polystyrene sulfonate that has humidity sensing features can be printed onto the top metal layer of a 0.35 μm CMOS IC. The developed printing-on-chip humidity sensor achieves a heterogeneous three dimensional sensor system-on-chip architecture. The humidity sensing of the implemented printing-on-chip sensor system is experimentally tested. The sensor shows a sensitivity of 0.98% to humidity in the atmosphere. The maximum dynamic range of the readout circuit is 9.8 MΩ, which can be further tuned by the frequency of input signal to fit the requirement of the resistance of printed sensor. The power consumption keeps only 154 μW. This printing-on-chip sensor provides a practical solution to fulfill an ultra-small integrated sensor for the applications in miniaturized sensing systems. PMID:24859027

Discrete distributed strain sensing of intelligent structures

NASA Technical Reports Server (NTRS)

Anderson, Mark S.; Crawley, Edward F.

1992-01-01

Techniques are developed for the design of discrete highly distributed sensor systems for use in intelligent structures. First the functional requirements for such a system are presented. Discrete spatially averaging strain sensors are then identified as satisfying the functional requirements. A variety of spatial weightings for spatially averaging sensors are examined, and their wave number characteristics are determined. Preferable spatial weightings are identified. Several numerical integration rules used to integrate such sensors in order to determine the global deflection of the structure are discussed. A numerical simulation is conducted using point and rectangular sensors mounted on a cantilevered beam under static loading. Gage factor and sensor position uncertainties are incorporated to assess the absolute error and standard deviation of the error in the estimated tip displacement found by numerically integrating the sensor outputs. An experiment is carried out using a statically loaded cantilevered beam with five point sensors. It is found that in most cases the actual experimental error is within one standard deviation of the absolute error as found in the numerical simulation.

Real-Time Identification of Smoldering and Flaming Combustion Phases in Forest Using a Wireless Sensor Network-Based Multi-Sensor System and Artificial Neural Network

PubMed Central

Yan, Xiaofei; Cheng, Hong; Zhao, Yandong; Yu, Wenhua; Huang, Huan; Zheng, Xiaoliang

2016-01-01

Diverse sensing techniques have been developed and combined with machine learning method for forest fire detection, but none of them referred to identifying smoldering and flaming combustion phases. This study attempts to real-time identify different combustion phases using a developed wireless sensor network (WSN)-based multi-sensor system and artificial neural network (ANN). Sensors (CO, CO2, smoke, air temperature and relative humidity) were integrated into one node of WSN. An experiment was conducted using burning materials from residual of forest to test responses of each node under no, smoldering-dominated and flaming-dominated combustion conditions. The results showed that the five sensors have reasonable responses to artificial forest fire. To reduce cost of the nodes, smoke, CO2 and temperature sensors were chiefly selected through correlation analysis. For achieving higher identification rate, an ANN model was built and trained with inputs of four sensor groups: smoke; smoke and CO2; smoke and temperature; smoke, CO2 and temperature. The model test results showed that multi-sensor input yielded higher predicting accuracy (≥82.5%) than single-sensor input (50.9%–92.5%). Based on these, it is possible to reduce the cost with a relatively high fire identification rate and potential application of the system can be tested in future under real forest condition. PMID:27527175

Real-Time Identification of Smoldering and Flaming Combustion Phases in Forest Using a Wireless Sensor Network-Based Multi-Sensor System and Artificial Neural Network.

PubMed

Yan, Xiaofei; Cheng, Hong; Zhao, Yandong; Yu, Wenhua; Huang, Huan; Zheng, Xiaoliang

2016-08-04

Diverse sensing techniques have been developed and combined with machine learning method for forest fire detection, but none of them referred to identifying smoldering and flaming combustion phases. This study attempts to real-time identify different combustion phases using a developed wireless sensor network (WSN)-based multi-sensor system and artificial neural network (ANN). Sensors (CO, CO₂, smoke, air temperature and relative humidity) were integrated into one node of WSN. An experiment was conducted using burning materials from residual of forest to test responses of each node under no, smoldering-dominated and flaming-dominated combustion conditions. The results showed that the five sensors have reasonable responses to artificial forest fire. To reduce cost of the nodes, smoke, CO₂ and temperature sensors were chiefly selected through correlation analysis. For achieving higher identification rate, an ANN model was built and trained with inputs of four sensor groups: smoke; smoke and CO₂; smoke and temperature; smoke, CO₂ and temperature. The model test results showed that multi-sensor input yielded higher predicting accuracy (≥82.5%) than single-sensor input (50.9%-92.5%). Based on these, it is possible to reduce the cost with a relatively high fire identification rate and potential application of the system can be tested in future under real forest condition.

Fast and accurate determination of the detergent efficiency by optical fiber sensors

NASA Astrophysics Data System (ADS)

Patitsa, Maria; Pfeiffer, Helge; Wevers, Martine

2011-06-01

An optical fiber sensor was developed to control the cleaning efficiency of surfactants. Prior to the measurements, the sensing part of the probe is covered with a uniform standardized soil layer (lipid multilayer), and a gold mirror is deposited at the end of the optical fiber. For the lipid multilayer deposition on the fiber, Langmuir-Blodgett technique was used and the progress of deposition was followed online by ultraviolet spectroscopy. The invention provides a miniaturized Surface Plasmon Resonance dip-sensor for automated on-line testing that can replace the cost and time consuming existing methods and develop a breakthrough in detergent testing in combining optical sensing, surface chemistry and automated data acquisition. The sensor is to be used to evaluate detergency of different cleaning products and also indicate how formulation, concentration, lipid nature and temperature affect the cleaning behavior of a surfactant.

Fusion of WiFi, smartphone sensors and landmarks using the Kalman filter for indoor localization.

PubMed

Chen, Zhenghua; Zou, Han; Jiang, Hao; Zhu, Qingchang; Soh, Yeng Chai; Xie, Lihua

2015-01-05

Location-based services (LBS) have attracted a great deal of attention recently. Outdoor localization can be solved by the GPS technique, but how to accurately and efficiently localize pedestrians in indoor environments is still a challenging problem. Recent techniques based on WiFi or pedestrian dead reckoning (PDR) have several limiting problems, such as the variation of WiFi signals and the drift of PDR. An auxiliary tool for indoor localization is landmarks, which can be easily identified based on specific sensor patterns in the environment, and this will be exploited in our proposed approach. In this work, we propose a sensor fusion framework for combining WiFi, PDR and landmarks. Since the whole system is running on a smartphone, which is resource limited, we formulate the sensor fusion problem in a linear perspective, then a Kalman filter is applied instead of a particle filter, which is widely used in the literature. Furthermore, novel techniques to enhance the accuracy of individual approaches are adopted. In the experiments, an Android app is developed for real-time indoor localization and navigation. A comparison has been made between our proposed approach and individual approaches. The results show significant improvement using our proposed framework. Our proposed system can provide an average localization accuracy of 1 m.

A novel fast phase correlation algorithm for peak wavelength detection of Fiber Bragg Grating sensors.

PubMed

Lamberti, A; Vanlanduit, S; De Pauw, B; Berghmans, F

2014-03-24

Fiber Bragg Gratings (FBGs) can be used as sensors for strain, temperature and pressure measurements. For this purpose, the ability to determine the Bragg peak wavelength with adequate wavelength resolution and accuracy is essential. However, conventional peak detection techniques, such as the maximum detection algorithm, can yield inaccurate and imprecise results, especially when the Signal to Noise Ratio (SNR) and the wavelength resolution are poor. Other techniques, such as the cross-correlation demodulation algorithm are more precise and accurate but require a considerable higher computational effort. To overcome these problems, we developed a novel fast phase correlation (FPC) peak detection algorithm, which computes the wavelength shift in the reflected spectrum of a FBG sensor. This paper analyzes the performance of the FPC algorithm for different values of the SNR and wavelength resolution. Using simulations and experiments, we compared the FPC with the maximum detection and cross-correlation algorithms. The FPC method demonstrated a detection precision and accuracy comparable with those of cross-correlation demodulation and considerably higher than those obtained with the maximum detection technique. Additionally, FPC showed to be about 50 times faster than the cross-correlation. It is therefore a promising tool for future implementation in real-time systems or in embedded hardware intended for FBG sensor interrogation.

Fusion of WiFi, Smartphone Sensors and Landmarks Using the Kalman Filter for Indoor Localization

PubMed Central

Chen, Zhenghua; Zou, Han; Jiang, Hao; Zhu, Qingchang; Soh, Yeng Chai; Xie, Lihua

2015-01-01

Location-based services (LBS) have attracted a great deal of attention recently. Outdoor localization can be solved by the GPS technique, but how to accurately and efficiently localize pedestrians in indoor environments is still a challenging problem. Recent techniques based on WiFi or pedestrian dead reckoning (PDR) have several limiting problems, such as the variation of WiFi signals and the drift of PDR. An auxiliary tool for indoor localization is landmarks, which can be easily identified based on specific sensor patterns in the environment, and this will be exploited in our proposed approach. In this work, we propose a sensor fusion framework for combining WiFi, PDR and landmarks. Since the whole system is running on a smartphone, which is resource limited, we formulate the sensor fusion problem in a linear perspective, then a Kalman filter is applied instead of a particle filter, which is widely used in the literature. Furthermore, novel techniques to enhance the accuracy of individual approaches are adopted. In the experiments, an Android app is developed for real-time indoor localization and navigation. A comparison has been made between our proposed approach and individual approaches. The results show significant improvement using our proposed framework. Our proposed system can provide an average localization accuracy of 1 m. PMID:25569750

Time and Memory Efficient Online Piecewise Linear Approximation of Sensor Signals.

PubMed

Grützmacher, Florian; Beichler, Benjamin; Hein, Albert; Kirste, Thomas; Haubelt, Christian

2018-05-23

Piecewise linear approximation of sensor signals is a well-known technique in the fields of Data Mining and Activity Recognition. In this context, several algorithms have been developed, some of them with the purpose to be performed on resource constrained microcontroller architectures of wireless sensor nodes. While microcontrollers are usually constrained in computational power and memory resources, all state-of-the-art piecewise linear approximation techniques either need to buffer sensor data or have an execution time depending on the segment’s length. In the paper at hand, we propose a novel piecewise linear approximation algorithm, with a constant computational complexity as well as a constant memory complexity. Our proposed algorithm’s worst-case execution time is one to three orders of magnitude smaller and its average execution time is three to seventy times smaller compared to the state-of-the-art Piecewise Linear Approximation (PLA) algorithms in our experiments. In our evaluations, we show that our algorithm is time and memory efficient without sacrificing the approximation quality compared to other state-of-the-art piecewise linear approximation techniques, while providing a maximum error guarantee per segment, a small parameter space of only one parameter, and a maximum latency of one sample period plus its worst-case execution time.

NVSIM: UNIX-based thermal imaging system simulator

NASA Astrophysics Data System (ADS)

Horger, John D.

1993-08-01

For several years the Night Vision and Electronic Sensors Directorate (NVESD) has been using an internally developed forward looking infrared (FLIR) simulation program. In response to interest in the simulation part of these projects by other organizations, NVESD has been working on a new version of the simulation, NVSIM, that will be made generally available to the FLIR using community. NVSIM uses basic FLIR specification data, high resolution thermal input imagery and spatial domain image processing techniques to produce simulated image outputs from a broad variety of FLIRs. It is being built around modular programming techniques to allow simpler addition of more sensor effects. The modularity also allows selective inclusion and exclusion of individual sensor effects at run time. The simulation has been written in the industry standard ANSI C programming language under the widely used UNIX operating system to make it easily portable to a wide variety of computer platforms.

Research on motor rotational speed measurement in regenerative braking system of electric vehicle

NASA Astrophysics Data System (ADS)

Pan, Chaofeng; Chen, Liao; Chen, Long; Jiang, Haobin; Li, Zhongxing; Wang, Shaohua

2016-01-01

Rotational speed signals acquisition and processing techniques are widely used in rotational machinery. In order to realized precise and real-time control of motor drive and regenerative braking process, rotational speed measurement techniques are needed in electric vehicles. Obtaining accurate motor rotational speed signal will contribute to the regenerative braking force control steadily and realized higher energy recovery rate. This paper aims to develop a method that provides instantaneous speed information in the form of motor rotation. It addresses principles of motor rotational speed measurement in the regenerative braking systems of electric vehicle firstly. The paper then presents ideal and actual Hall position sensor signals characteristics, the relation between the motor rotational speed and the Hall position sensor signals is revealed. Finally, Hall position sensor signals conditioning and processing circuit and program for motor rotational speed measurement have been carried out based on measurement error analysis.

A survey and analysis of experimental hydrogen sensors

NASA Technical Reports Server (NTRS)

Hunter, Gary W.

1992-01-01

In order to ascertain the applicability of hydrogen sensors to aerospace applications, a survey was conducted of promising experimental point-contact hydrogen sensors and their operation was analyzed. The techniques discussed are metal-oxide-semiconductor or MOS based sensors, catalytic resistor sensors, acoustic wave detectors, and pyroelectric detectors. All of these sensors depend on the interaction of hydrogen with Pd or a Pd-alloy. It is concluded that no single technique will meet the needs of aerospace applications but a combination of approaches is necessary. The most promising combination is an MOS based sensor with a catalytic resistor.

An optical sensing approach for the noninvasive transdermal monitoring of cortisol

NASA Astrophysics Data System (ADS)

Hwang, Yongsoon; Gupta, Niraj K.; Ojha, Yagya R.; Cameron, Brent D.

2016-03-01

Cortisol, a biomarker of stress, has recently been shown to have potential in evaluating the physiological state of individuals diagnosed with stress-related conditions including chronic fatigue syndrome. Noninvasive techniques to extract biomarkers from the body are a topic of considerable interest. One such technique to achieve this is known as reverse iontophoresis (RI) which is capable of extracting biomolecules through the skin. Unfortunately, however, the extracted levels are often considerably lower in concentration than those found in blood, thereby requiring a very sensitive analytical method with a low limit of detection. A promising sensing approach, which is well suited to handle such samples, is Surface Plasmon Resonance (SPR) spectroscopy. When coupled with aptamer modified surfaces, such sensors can achieve both selectivity and the required sensitivity. In this study, fabrication and characterization of a RIbased SPR biosensor for the measurement of cortisol has been developed. The optical mount and diffusion cell were both fabricated through the use of 3D printing techniques. The SPR sensor was configured to employ a prism couplerbased arrangement with a laser generation module and CCD line sensor. Cortisol-specific DNA aptamers were immobilized onto a gold surface to achieve the necessary selectivity. For demonstration purposes, cortisol was extracted by the RI system using a skin phantom flow system capable of generating time dependent concentration profiles. The captured sample was then transported using a micro-fluidic platform from the RI collection site to the SPR sensor for real-time monitoring. Analysis and system control was accomplished within a developed LabVIEW® program.

Cloud Water Content Sensor for Sounding Balloons and Small UAVs

NASA Technical Reports Server (NTRS)

Bognar, John A.

2009-01-01

A lightweight, battery-powered sensor was developed for measuring cloud water content, which is the amount of liquid or solid water present in a cloud, generally expressed as grams of water per cubic meter. This sensor has near-zero power consumption and can be flown on standard sounding balloons and small, unmanned aerial vehicles (UAVs). The amount of solid or liquid water is important to the study of atmospheric processes and behavior. Previous sensing techniques relied on strongly heating the incoming air, which requires a major energy input that cannot be achieved on sounding balloons or small UAVs.

Symposium Gyro Technology 1984; Proceedings of the Symposium, Universitaet Stuttgart, West Germany, September 11, 12, 1984

NASA Astrophysics Data System (ADS)

Sorg, H.

Among the topics discussed are: drift and scale factor tests on the SEL fiber gyro; integrated optical rate sensor development; and the beam geometry of a ring laser gyro in relation to its performance. Consideration is also given to: a fast filtering technique for measuring random walk in a laser gyro; vibratory gyroscopic sensors; a redundant strapdown reference for advanced aircraft flight control systems; and a low-cost piezoelectric rate/acceleration sensor. Additional topics include: an inertial guidance system for a Low-Earth-Orbit (LEO) vehicle; and signal disturbance effects in a strapdown northfinder.

Development of integrated optical tracking sensor by planar optics

NASA Astrophysics Data System (ADS)

Kawano, Hiroyuki; Sasagawa, Tomohiro; Nishimae, Junichi; Sato, Yukio

1999-03-01

A compact and light weight optical tracking sensor for a large capacity flexible disk drive is demonstrated. The size of the optical element is no larger than 5.4 mm in length X 3.6 mm in width X 1.2 mm in height and the weight is only 18 mg. The application of the planar optical technique makes it possible to integrate all passive optical elements onto one transparent substrate. These features are useful for high- speed access, easy optical alignment, mass production, and miniaturization. The design and optical characteristics of the optical tracking sensor are described.

Characterization techniques for incorporating backgrounds into DIRSIG

NASA Astrophysics Data System (ADS)

Brown, Scott D.; Schott, John R.

2000-07-01

The appearance of operation hyperspectral imaging spectrometers in both solar and thermal regions has lead to the development of a variety of spectral detection algorithms. The development and testing of these algorithms requires well characterized field collection campaigns that can be time and cost prohibitive. Radiometrically robust synthetic image generation (SIG) environments that can generate appropriate images under a variety of atmospheric conditions and with a variety of sensors offers an excellent supplement to reduce the scope of the expensive field collections. In addition, SIG image products provide the algorithm developer with per-pixel truth, allowing for improved characterization of the algorithm performance. To meet the needs of the algorithm development community, the image modeling community needs to supply synthetic image products that contain all the spatial and spectral variability present in real world scenes, and that provide the large area coverage typically acquired with actual sensors. This places a heavy burden on synthetic scene builders to construct well characterized scenes that span large areas. Several SIG models have demonstrated the ability to accurately model targets (vehicles, buildings, etc.) Using well constructed target geometry (from CAD packages) and robust thermal and radiometry models. However, background objects (vegetation, infrastructure, etc.) dominate the percentage of real world scene pixels and utilizing target building techniques is time and resource prohibitive. This paper discusses new methods that have been integrated into the Digital Imaging and Remote Sensing Image Generation (DIRSIG) model to characterize backgrounds. The new suite of scene construct types allows the user to incorporate both terrain and surface properties to obtain wide area coverage. The terrain can be incorporated using a triangular irregular network (TIN) derived from elevation data or digital elevation model (DEM) data from actual sensors, temperature maps, spectral reflectance cubes (possible derived from actual sensors), and/or material and mixture maps. Descriptions and examples of each new technique are presented as well as hybrid methods to demonstrate target embedding in real world imagery.

Application of historical mobility testing to sensor-based robotic performance

NASA Astrophysics Data System (ADS)

Willoughby, William E.; Jones, Randolph A.; Mason, George L.; Shoop, Sally A.; Lever, James H.

2006-05-01

The USA Engineer Research and Development Center (ERDC) has conducted on-/off-road experimental field testing with full-sized and scale-model military vehicles for more than fifty years. Some 4000 acres of local terrain are available for tailored field evaluations or verification/validation of future robotic designs in a variety of climatic regimes. Field testing and data collection procedures, as well as techniques for quantifying terrain in engineering terms, have been developed and refined into algorithms and models for predicting vehicle-terrain interactions and resulting forces or speeds of military-sized vehicles. Based on recent experiments with Matilda, Talon, and Pacbot, these predictive capabilities appear to be relevant to most robotic systems currently in development. Utilization of current testing capabilities with sensor-based vehicle drivers, or use of the procedures for terrain quantification from sensor data, would immediately apply some fifty years of historical knowledge to the development, refinement, and implementation of future robotic systems. Additionally, translation of sensor-collected terrain data into engineering terms would allow assessment of robotic performance a priori deployment of the actual system and ensure maximum system performance in the theater of operation.

a Low-Power Wireless Sensor Network for Monitoring the Microcrack Initiations in Aerospace Composites

NASA Astrophysics Data System (ADS)

Li, Jian; Plotnikov, Yuri; Lin, Wendy W.

2008-02-01

A low power wireless sensor network was developed to monitor the microcrack events in aerospace composites. The microcracks in the composites mostly result from a stress loading or temperature and/or humidity cycles. Generally, a single microcrack is too small to be detected by conventional techniques such as X-ray or ultrasonic C-scan. The whole developed sensor network is aimed to capture the released acoustic signals by the microcracking events in real time. It comprises of a receiving station as well as a series of sensor nodes. Each sensor node includes two acoustic emission transducers as well as two signal amplification and data acquisition channels. Much of our development effort has been focused on reducing the power consumption of each node and improving the detection reliability for each event. Each sensor node is battery-powered and works in a sleep mode most of time. Once a microcrack is initiated in the composite, the acoustic signal triggers the node and wakes it up. The node will then react in several microseconds and digitize the signal. The digitized data is sent to the station wirelessly. The developed wireless sensor network system has been validated with microscopy of microcracked samples after temperature and humidity cycling and has proved to be an effective tool for microcracking detection. Furthermore, our low power consumption design and sophisticated wireless transmission mechanism enables a system with great potential for field structural health monitoring applications.

Advances in Multi-Sensor Information Fusion: Theory and Applications 2017.

PubMed

Jin, Xue-Bo; Sun, Shuli; Wei, Hong; Yang, Feng-Bao

2018-04-11

The information fusion technique can integrate a large amount of data and knowledge representing the same real-world object and obtain a consistent, accurate, and useful representation of that object. The data may be independent or redundant, and can be obtained by different sensors at the same time or at different times. A suitable combination of investigative methods can substantially increase the profit of information in comparison with that from a single sensor. Multi-sensor information fusion has been a key issue in sensor research since the 1970s, and it has been applied in many fields. For example, manufacturing and process control industries can generate a lot of data, which have real, actionable business value. The fusion of these data can greatly improve productivity through digitization. The goal of this special issue is to report innovative ideas and solutions for multi-sensor information fusion in the emerging applications era, focusing on development, adoption, and applications.

A Bionic Polarization Navigation Sensor and Its Calibration Method.

PubMed

Zhao, Huijie; Xu, Wujian

2016-08-03

The polarization patterns of skylight which arise due to the scattering of sunlight in the atmosphere can be used by many insects for deriving compass information. Inspired by insects' polarized light compass, scientists have developed a new kind of navigation method. One of the key techniques in this method is the polarimetric sensor which is used to acquire direction information from skylight. In this paper, a polarization navigation sensor is proposed which imitates the working principles of the polarization vision systems of insects. We introduce the optical design and mathematical model of the sensor. In addition, a calibration method based on variable substitution and non-linear curve fitting is proposed. The results obtained from the outdoor experiments provide support for the feasibility and precision of the sensor. The sensor's signal processing can be well described using our mathematical model. A relatively high degree of accuracy in polarization measurement can be obtained without any error compensation.

On-line soft sensing in upstream bioprocessing.

PubMed

Randek, Judit; Mandenius, Carl-Fredrik

2018-02-01

This review provides an overview and a critical discussion of novel possibilities of applying soft sensors for on-line monitoring and control of industrial bioprocesses. Focus is on bio-product formation in the upstream process but also the integration with other parts of the process is addressed. The term soft sensor is used for the combination of analytical hardware data (from sensors, analytical devices, instruments and actuators) with mathematical models that create new real-time information about the process. In particular, the review assesses these possibilities from an industrial perspective, including sensor performance, information value and production economy. The capabilities of existing analytical on-line techniques are scrutinized in view of their usefulness in soft sensor setups and in relation to typical needs in bioprocessing in general. The review concludes with specific recommendations for further development of soft sensors for the monitoring and control of upstream bioprocessing.

SQUID (superconducting quantum interference device) arrays for simultaneous magnetic measurements: Calibration and source localization performance

NASA Astrophysics Data System (ADS)

Kaufman, Lloyd; Williamson, Samuel J.; Costaribeiro, P.

1988-02-01

Recently developed small arrays of SQUID-based magnetic sensors can, if appropriately placed, locate the position of a confined biomagnetic source without moving the array. The authors present a technique with a relative accuracy of about 2 percent for calibrating such sensors having detection coils with the geometry of a second-order gradiometer. The effects of calibration error and magnetic noise on the accuracy of locating an equivalent current dipole source in the human brain are investigated for 5- and 7-sensor probes and for a pair of 7-sensor probes. With a noise level of 5 percent of peak signal, uncertainties of about 20 percent in source strength and depth for a 5-sensor probe are reduced to 8 percent for a pair of 7-sensor probes, and uncertainties of about 15 mm in lateral position are reduced to 1 mm, for the configuration considered.

Sensor-Only System Identification for Structural Health Monitoring of Advanced Aircraft

NASA Technical Reports Server (NTRS)

Kukreja, Sunil L.; Bernstein, Dennis S.

2012-01-01

Environmental conditions, cyclic loading, and aging contribute to structural wear and degradation, and thus potentially catastrophic events. The challenge of health monitoring technology is to determine incipient changes accurately and efficiently. This project addresses this challenge by developing health monitoring techniques that depend only on sensor measurements. Since actively controlled excitation is not needed, sensor-to-sensor identification (S2SID) provides an in-flight diagnostic tool that exploits ambient excitation to provide advance warning of significant changes. S2SID can subsequently be followed up by ground testing to localize and quantify structural changes. The conceptual foundation of S2SID is the notion of a pseudo-transfer function, where one sensor is viewed as the pseudo-input and another is viewed as the pseudo-output, is approach is less restrictive than transmissibility identification and operational modal analysis since no assumption is made about the locations of the sensors relative to the excitation.

Fused Filament Fabrication of Prosthetic Components for Trans-Humeral Upper Limb Prosthetics

NASA Astrophysics Data System (ADS)

Lathers, Steven M.

Presented below is the design and fabrication of prosthetic components consisting of an attachment, tactile sensing, and actuator systems with Fused Filament Fabrication (FFF) technique. The attachment system is a thermoplastic osseointegrated upper limb prosthesis for average adult trans-humeral amputation with mechanical properties greater than upper limb skeletal bone. The prosthetic designed has: a one-step surgical process, large cavities for bone tissue ingrowth, uses a material that has an elastic modulus less than skeletal bone, and can be fabricated on one system. FFF osseointegration screw is an improvement upon the current two-part osseointegrated prosthetics that are composed of a fixture and abutment. The current prosthetic design requires two invasive surgeries for implantation and are made of titanium, which has an elastic modulus greater than bone. An elastic modulus greater than bone causes stress shielding and overtime can cause loosening of the prosthetic. The tactile sensor is a thermoplastic piezo-resistive sensor for daily activities for a prosthetic's feedback system. The tactile sensor is manufactured from a low elastic modulus composite comprising of a compressible thermoplastic elastomer and conductive carbon. Carbon is in graphite form and added in high filler ratios. The printed sensors were compared to sensors that were fabricated in a gravity mold to highlight the difference in FFF sensors to molded sensors. The 3D printed tactile sensor has a thickness and feel similar to human skin, has a simple fabrication technique, can detect forces needed for daily activities, and can be manufactured in to user specific geometries. Lastly, a biomimicking skeletal muscle actuator for prosthetics was developed. The actuator developed is manufactured with Fuse Filament Fabrication using a shape memory polymer composite that has non-linear contractile and passive forces, contractile forces and strains comparable to mammalian skeletal muscle, reaction time under one second, low operating temperature, and has a low mass, volume, and material costs. The actuator improves upon current prosthetic actuators that provide rigid, linear force with high weight, cost, and noise.

Development of lidar sensor for cloud-based measurements during convective conditions

NASA Astrophysics Data System (ADS)

Vishnu, R.; Bhavani Kumar, Y.; Rao, T. Narayana; Nair, Anish Kumar M.; Jayaraman, A.

2016-05-01

Atmospheric convection is a natural phenomena associated with heat transport. Convection is strong during daylight periods and rigorous in summer months. Severe ground heating associated with strong winds experienced during these periods. Tropics are considered as the source regions for strong convection. Formation of thunder storm clouds is common during this period. Location of cloud base and its associated dynamics is important to understand the influence of convection on the atmosphere. Lidars are sensitive to Mie scattering and are the suitable instruments for locating clouds in the atmosphere than instruments utilizing the radio frequency spectrum. Thunder storm clouds are composed of hydrometers and strongly scatter the laser light. Recently, a lidar technique was developed at National Atmospheric Research Laboratory (NARL), a Department of Space (DOS) unit, located at Gadanki near Tirupati. The lidar technique employs slant path operation and provides high resolution measurements on cloud base location in real-time. The laser based remote sensing technique allows measurement of atmosphere for every second at 7.5 m range resolution. The high resolution data permits assessment of updrafts at the cloud base. The lidar also provides real-time convective boundary layer height using aerosols as the tracers of atmospheric dynamics. The developed lidar sensor is planned for up-gradation with scanning facility to understand the cloud dynamics in the spatial direction. In this presentation, we present the lidar sensor technology and utilization of its technology for high resolution cloud base measurements during convective conditions over lidar site, Gadanki.

Plasmonic improvement of microcavity biomedical sensor spectroscopic characteristics

NASA Astrophysics Data System (ADS)

Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Saetchnikov, Anton V.; Schweiger, Gustav; Ostendorf, Andreas; Ghadiri, Reza

2014-03-01

New opportunity to improve a sensetivity of a label-free biomolecule detection in sensing systems based on microcavity evanescent wave optical sensors has been recently found and is being under intensive development. Novel technique based on combination of optical resonance on microring structures with plasmon resonance. Recently developed tools based on neural network data processing can realize real-time identification of biological agents. So combining advantages of plasmon enhancing optical microcavity resonance with identification tools can give a new platform for ulta sensitive label-free biomedical sensor. Our developed technique used standard glass and polymer microspheres as sensetive elements. They are fixed in the solution flow by adhesive layer on the surface being in the field of evanescence wave. Sensitive layer have been treated by gold nanoparticel (GN) solution. Another technique used thin film gold layers deposited on the substrate below adhesive. The light from a tuneable diode laser is coupled into the microsphere through a prism and was sharply focussed on the single microsphere. Images were recorded by CMOS camera. Normalized by free spectral range resonance shift of whispering gallery mode (WGM) and a relative efficiency of their excitation were used as input data for biomolecule classification. Both biomolecules and NP injection was obtained caused WGM spectra modification. But after NP treatment spectral shift and intensity of WGM resonances in biomolecule solutions increased. WGM resonances in microspheres fixed on substrate with gold layer with optimized layer thickness in biomolecule solutions also had higher intensity and spectra modification then without gold layer.

Air Force and Army Corps of Engineers Improperly Managed the Award of Contracts for the Blue Devil Block 2 Persistent Surveillance System

DTIC Science & Technology

2013-09-19

environments. This can include the development of new and/or improved analytical and numerical models, rapid data-processing techniques, and new subsurface ... imaging techniques that include active and passive sensor modalities in a variety of rural and urban terrains. Of particular interest is the broadband

Optical techniques for the determination of nitrate in environmental waters: Guidelines for instrument selection, operation, deployment, maintenance, quality assurance, and data reporting

USGS Publications Warehouse

Pellerin, Brian A.; Bergamaschi, Brian A.; Downing, Bryan D.; Saraceno, John Franco; Garrett, Jessica D.; Olsen, Lisa D.

2013-01-01

The recent commercial availability of in situ optical sensors, together with new techniques for data collection and analysis, provides the opportunity to monitor a wide range of water-quality constituents on time scales in which environmental conditions actually change. Of particular interest is the application of ultraviolet (UV) photometers for in situ determination of nitrate concentrations in rivers and streams. The variety of UV nitrate sensors currently available differ in several important ways related to instrument design that affect the accuracy of their nitrate concentration measurements in different types of natural waters. This report provides information about selection and use of UV nitrate sensors by the U.S. Geological Survey to facilitate the collection of high-quality data across studies, sites, and instrument types. For those in need of technical background and information about sensor selection, this report addresses the operating principles, key features and sensor design, sensor characterization techniques and typical interferences, and approaches for sensor deployment. For those needing information about maintaining sensor performance in the field, key sections in this report address maintenance and calibration protocols, quality-assurance techniques, and data formats and reporting. Although the focus of this report is UV nitrate sensors, many of the principles can be applied to other in situ optical sensors for water-quality studies.

Graphene Nanoplatelet-Polymer Chemiresistive Sensor Arrays for the Detection and Discrimination of Chemical Warfare Agent Simulants.

PubMed

Wiederoder, Michael S; Nallon, Eric C; Weiss, Matt; McGraw, Shannon K; Schnee, Vincent P; Bright, Collin J; Polcha, Michael P; Paffenroth, Randy; Uzarski, Joshua R

2017-11-22

A cross-reactive array of semiselective chemiresistive sensors made of polymer-graphene nanoplatelet (GNP) composite coated electrodes was examined for detection and discrimination of chemical warfare agents (CWA). The arrays employ a set of chemically diverse polymers to generate a unique response signature for multiple CWA simulants and background interferents. The developed sensors' signal remains consistent after repeated exposures to multiple analytes for up to 5 days with a similar signal magnitude across different replicate sensors with the same polymer-GNP coating. An array of 12 sensors each coated with a different polymer-GNP mixture was exposed 100 times to a cycle of single analyte vapors consisting of 5 chemically similar CWA simulants and 8 common background interferents. The collected data was vector normalized to reduce concentration dependency, z-scored to account for baseline drift and signal-to-noise ratio, and Kalman filtered to reduce noise. The processed data was dimensionally reduced with principal component analysis and analyzed with four different machine learning algorithms to evaluate discrimination capabilities. For 5 similarly structured CWA simulants alone 100% classification accuracy was achieved. For all analytes tested 99% classification accuracy was achieved demonstrating the CWA discrimination capabilities of the developed system. The novel sensor fabrication methods and data processing techniques are attractive for development of sensor platforms for discrimination of CWA and other classes of chemical vapors.

Overcoming urban GPS navigation challenges through the use of MEMS inertial sensors and proper verification of navigation system performance

NASA Astrophysics Data System (ADS)

Vinande, Eric T.

This research proposes several means to overcome challenges in the urban environment to ground vehicle global positioning system (GPS) receiver navigation performance through the integration of external sensor information. The effects of narrowband radio frequency interference and signal attenuation, both common in the urban environment, are examined with respect to receiver signal tracking processes. Low-cost microelectromechanical systems (MEMS) inertial sensors, suitable for the consumer market, are the focus of receiver augmentation as they provide an independent measure of motion and are independent of vehicle systems. A method for estimating the mounting angles of an inertial sensor cluster utilizing typical urban driving maneuvers is developed and is able to provide angular measurements within two degrees of truth. The integration of GPS and MEMS inertial sensors is developed utilizing a full state navigation filter. Appropriate statistical methods are developed to evaluate the urban environment navigation improvement due to the addition of MEMS inertial sensors. A receiver evaluation metric that combines accuracy, availability, and maximum error measurements is presented and evaluated over several drive tests. Following a description of proper drive test techniques, record and playback systems are evaluated as the optimal way of testing multiple receivers and/or integrated navigation systems in the urban environment as they simplify vehicle testing requirements.

Monitoring the bending and twist of morphing structures

NASA Astrophysics Data System (ADS)

Smoker, J.; Baz, A.

2008-03-01

This paper presents the development of the theoretical basis for the design of sensor networks for determining the 2-dimensioal shape of morphing structures by monitoring simultaneously the bending and twist deflections. The proposed development is based on the non-linear theory of finite elements to extract the transverse linear and angular deflections of a plate-like structure. The sensors outputs are wirelessly transmitted to the command unit to simultaneously compute maps of the linear and angular deflections and maps of the strain distribution of the entire structure. The deflection and shape information are required to ascertain that the structure is properly deployed and that its surfaces are operating wrinkle-free. The strain map ensures that the structure is not loaded excessively to adversely affect its service life. The developed theoretical model is validated experimentally using a prototype of a variable cambered span morphing structure provided with a network of distributed sensors. The structure/sensor network system is tested under various static conditions to determine the response characteristics of the proposed sensor network as compared to other conventional sensor systems. The presented theoretical and experimental techniques can have a great impact on the safe deployment and effective operation of a wide variety of morphing and inflatable structures such as morphing aircraft, solar sails, inflatable wings, and large antennas.